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OpenWebRX+
A Better Online SDR Radio
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This document is about
OpenWebRX+,
an improved and extended version of the original
OpenWebRX
web-based SDR radio. For casual radio listeners, it explains how to use
online OpenWebRX+ receivers and what you can do with them. For those
interested in hosting their own OpenWebRX+ receiver, there are
installation instructions and advice for selecting the hardware.

OpenWebRX+ adds many features missing from the original OpenWebRX, such
as noise reduction, tuning steps, scanner, keyboard shortcuts, improved
user interface and maps, and decoders for many digital communication
protocols. Please note that the following document covers both
the original OpenWebRX and the extended OpenWebRX+. Features specific to
OpenWebRX+ are marked so.

How to Get OpenWebRX+

Public receivers
are located all over the globe and can be found via the
ReceiverBook
website.

Binary packages
for the latest Ubuntu and Debian Linux can be installed from
this package repository.
Please, carefully read
the instructions
there before trying to install. The correct installation should
completely and cleanly replace the original OpenWebRX packages, if
they are installed on your system.

The source code
is available from my Github account. Most development happens in the
«master» branches of the relevant repos, such as csdr,
pycsdr, owrx_connector, and openwebrx. Some
packages are reused from the «master» branches of the original
OpenWebRX repos without changes.

News and announcements
are posted to a Telegram channel.
The support and discussion
occurs in a Telegram chat.

Table of Contents

How to Use OpenWebRX+

Main Display
Main Controls
Using Mouse and Touch
Using Keyboard
Frequency Scanner
Built-in Chat

Map Display

Locators
Markers
Other Online Receivers
Shortwave Stations
Repeaters

Broadcast Radio

Listening to FM Broadcasts
Listening to AM Broadcasts
Shortwave Listening (SWL)
HDRadio: Digital FM in America
DAB: Digital FM in Europe

Amateur Radio

Listening to Citizens Band (CB)
Listening to HAM Bands
Listening to Morse Code (CW)
Receiving Teletype (RTTY)
Receiving SSTV Images
Tracking Packet Radio (APRS)

Digital Communications

Receiving Fax Images
Monitoring Pager Messages (POCSAG)
Monitoring Wireless Devices (ISM)

Aeronautic Communications

Tracking Airplanes (ADS-B)
Long Range Communications (HFDL)
Short Range Communications (VDL2)
Legacy Communications (ACARS)

Maritime Communications

Tracking Ships (AIS)
Maritime Safety Information (MSI)
Navigational Telex (NAVTEX)
Digital Selective Calling (DSC)

Installing OpenWebRX+

Installing on Ubuntu 22.04
Installing on Ubuntu 24.04
Installing on Debian Bullseye
Installing on Debian Bookworm
Installing from Packages
Using Raspberry Pi SD Images
Using Docker Images
Building OpenWebRX+ from Sources

Hardware Setup

RTL-SDR Devices
SDRPlay (RSP) Devices
Airspy Devices
Hermes Lite 2
HackRF One
Choosing an Antenna

Administrator Features

Background Decoding
Scheduled Decoding
Reporting Decoded Data
Configuring Map
Configuring Shortwave Schedules
Configuring Repeaters
Limiting Receiver Use
Monitoring Receiver Use
Advanced MQTT Reporting
JavaScript Plugins
External Transceiver Rig Control
Receiving Satellite Data

Frequently Asked Questions

How to Use OpenWebRX+

Since OpenWebRX is a server designed to share SDR resources among
multiple users, its operation is somewhat different from regular SDR
applications. This section explains the basics of OpenWebRX usage,
including the main display and controls.

Main Display

The scrolling waterfall shows the band activity in your currently
selected SDR profile. The waterfall colors represent signal levels at
each frequency, with brighter colors corresponding to stronger signals.
Thus, a strong, healthy, ongoing signal will look like a bright vertical
stripe at the waterfall. Different signal modulations produce
differently shaped stripes. See
Signal Identification Guide
for examples.

The frequency scale shows the actual frequencies, as well as the
currently tuned frequency, represented with the yellow caret. This is
the frequency you are currently listening to. The numbers at the
caret sides stand for the current filter bounds. You can change these
bounds by dragging the caret sides.

The spectrum display, found in OpenWebRX+, shows the
current signal level at each frequency, as opposed to the
historic level shown by the waterfall. The spectrum display has a little
bit of latency, to make sure that short signals still leave their mark
on the spectrum.

The step-tuning buttons let you tune up and down the frequency
scale by left-clicking them. With the «side-stepping» feature enabled,
you can also right-click these buttons to step outside your currently
selected profile.

The bookmarks let you quickly tune to previously bookmarked
frequencies. There are three types of bookmarks in OpenWebRX:

Green bookmarks represent frequencies defined by the band plan.
These bookmarks are not editable, other than by modifying the band plan.

Yellow bookmarks are saved on the OpenWebRX server and can be
edited by the administrator.

Blue bookmarks are saved in your web browser and can thus be
created and edited by you.

The receiver information is shown by clicking the icon at the
top-left page corner. This information is filled in by the
administrator and includes receiver’s name, location and the hardware
description.

The Status button toggles the status
bar shown at the bottom of the receiver web page.

The Chat button toggles the log and chat
panel shown at the bottom of the receiver web page. If the
administrator has chosen to disable chat functionality, this button will
turn into Log, opening the non-interactive
log panel instead.

The Receiver button toggles the main
control panel for the receiver.

The Map button opens the map page
showing radio stations, repeaters, other online receivers, and position
reports from various sources, such as airplanes, ships, and HAM
operators.

The Files button opens the file browser
page with the most recently received SSTV images, faxes, and other
data.

The Settings button opens the password
protected settings page for configuring OpenWebRX. Normally, only
server administrator needs to access the server settings.

The status bar at the bottom of receiver’s page displays the
current status of the server and its connection to your web browser.
Various panels show network throughput, server CPU load and temperature,
audio sampling rate, and so on.

Main Controls

This is the currently tuned frequency of the receiver. You can
change it by clicking on the waterfall, the bookmarks, or by entering it
directly into this field. The frequency can only be changed within
the current profile bounds.

Click this button to bookmark your current frequency. The new
bookmark will be stored locally in your browser and appear as a blue
marker above the waterfall.

This is the current profile, including the SDR device name
(«RSPdx»). OpenWebRX supports multiple SDR devices with multiple
profiles for each device. When selecting a new profile, remember that it
will change for all users of the same SDR device, so be
considerate when you see somebody else using the server.

This is the list of all available audio modulation modes, with
the current mode highlighted in yellow. Select a new mode by clicking
corresponding button, but keep in mind that not all modes can be
applicable. It helps to know what each modulation looks like on the
waterfall. Consult the
Signal Identification Guide
if unsure.

This button will light up if a digital decoder is active. Click
it to toggle digital decoding off.

This is the current digital decoding mode, if active. You can
select a new digital decoding mode from the list here, but keep in mind
that not all modes can be applicable. It helps to know what each digital
mode looks like on the waterfall. Consult the
Signal Identification Guide
if unsure.

Use this slider to control audio volume. Click the speaker button
to mute or unmute audio.

Use this slider to set the squelch threshold. Left-click the
SQ button to toggle squelch on and off. When
the squelch is on, any audio that is below the selected squelch
threshold will be muted.

Right-clicking the SQ button toggles the
frequency scanner, making SQ button glow
green. The scanner will automatically check all bookmarked frequencies
for signals that are above the squelch threshold and tune to them. Once
a signal disappears, the scanner will continue checking bookmarks for
more signals.

Use this slider to set the noise reduction threshold. Click the
NR button to toggle noise reduction on and
off. The noise reduction algorithm works on the spectral subtraction
principle. It will remove any frequencies that are below the selected
threshold from the audio, reducing the background noise. Remember that
excessive use of noise reduction may distort or muffle the useful sounds
though.

The tuning step selector lets you choose the frequency tuning
granularity. For example, if 1kHz step is selected, the frequency will
always tune in 1kHz increments. Different profiles may assume different
default tuning steps, such as 5kHz for shortwave broadcasters or 500Hz
for HAM operators using SSB modulation. Click the adjacent button to
reset tuning step to its default value for the current profile.

This slider sets the signal level for the «hottest» waterfall
color (usually red). Set it higher when looking at strong signals,
lower when looking at weak signals.

Left-click the adjacent button to make a one-time automatic adjustment
of the waterfall colors. Right-click the button to toggle continuous
automatic adjustment of the waterfall colors.

This slider sets the signal level for the «coldest» waterfall
color (usually blue). Set it higher when looking at strong signals,
lower when looking at weak signals.

Left-click the adjacent button to reset waterfall colors to their
default values.

This drop-down list lets you choose one of the user interface
themes. Clicking the adjacent button resets user interface to the
default theme.

This slider controls the user interface opacity, making panels
more or less visible on top of the waterfall. Click the adjacent button
to reset user interface to the full opacity.

The four zoom buttons let you zoom waterfall in and out. Zooming
always happens around the currently tuned frequency, keeping it on
display.

The clock at the bottom of the main panel shows the current Universal
Coordinated Time (UTC). Most of the OpenWebRX user interface
operates in UTC, so this clock is shown for easier reference.

Click the REC button to start recording
audio at any moment. The button will glow red, indicating ongoing
recording. Once you click the REC button
again, it will stop recording and save the recorded audio to a file.

The bar at the bottom indicates the current signal level. It will
change color based on what OpenWebRX considers signal overload. There is
also a numeric readout, showing the exact value in decibels.

This button toggles the live spectrum display above the
waterfall. When using it, keep in mind that the spectrum display may
make your web browser use a lot of processor power.

Using Mouse and Touch

OpenWebRX requires the use of the right mouse button. On devices with
a single mouse button (such as Apple computers), the right mouse
button is simulated by holding the CONTROL
key with a mouse click.

On touch-based devices, such as smartphones and tablets, the
right mouse button is simulated by holding the spot with your finger for
a little bit longer than usual.

The mouse scroll wheel operates in two modes: normal and
modified (with the right mouse button, the wheel button, or the
SHIFT key pressed):

In the waterfall:
Normal wheel spin tunes frequency, modified wheel spin changes zoom
factor. This behavior can be reversed with a checkbox found in the
receiver panel.

In the frequency scale:
Both normal and modified wheel spins tune frequency.

At the bandpass filter (yellow caret):
Normal wheel spin shifts filter left or right, modified wheel spin makes
filter wider or narrower.

Using Keyboard

OpenWebRX+ includes keyboard shortcuts for accessing the most common
interface functions. To see the complete list of shortcuts, press the
? key, which opens the following panel:

Frequency Scanner

What is a scanner?

The OpenWebRX+ includes a frequency scanner that can monitor currently
shown bookmarks for activity. When the scanner detects a signal at one
of the bookmarked frequencies, it will tune to that frequency. Once that
frequency goes quiet, the scanner goes back to monitoring all shown
bookmarks. In order to use the scanner, do the following:

Choose a profile with some bookmarked frequencies you are interested in.

Tune to an empty part of the waterfall and left-click the
SQ button in order to set the squelch level.

Right-click the SQ button to start scanning.
The SQ button will glow green indicating
that the scanner is on. Mobile device users can simply hold the button
down for a longer time to simulate the right-click.

Once done, right-click the SQ button again
to disable the scanner.

Please, keep in mind that the scanner will not work on digital voice
channels, since they tend to keep signal on even if there is no
actual traffic on a channel.

Built-In Chat

OpenWebRX+ includes a simple chat that lets connected users talk to each
other. The chat panel opens by pressing the Chat
button at the top of the receiver web page.

When you send your first chat message by entering it at the bottom of
the chat window, OpenWebRX+ will assign you a random nickname, shown to
other users next to your messages. To change your name, enter
your new nickname at the left of the message input.

The server administrator can disable chat functionality via the
settings. When disabled, the Chat button
turns into the Log button, with the log
panel not accepting any input from users.

Map Display

OpenWebRX has a map display showing the received data, such as ship
and airplane locations, APRS reports, and digital HAM messages. You can
reveal the map by clicking the Map button
at the top of the browser window.

OpenWebRX+ offers two map types: Google Maps and a collection
of free maps based on the Leaflet library. The very popular
OpenStreetMap is a part of that collection. You can switch
between map types by clicking the Map button
at the top of the browser window.

The above image shows OpenWebRX+ Google Maps interface. Aside
from the regular navigation controls, this interface presents a toolbox
at the left side with toggle switches for different kinds of data. New
switches will appear as OpenWebRX receives new kinds of data, such as
ship or aircraft positions for example.

The large red marker indicates the receiver location. Colored «locator»
squares represent origins of digital HAM transmissions, such as FT8,
FT4, or WSPR reports, with each elemental color representing either
frequency (when «By Band» selected) or mode (when «By
Mode» selected). Individual colors can be clicked on and off in
the toolbox.

Locators

By clicking on a colored locator square, you can see all the reports
received from its location, as shown below. The information bubble also
indicates locator’s name
(using Maidenhead System),
its distance from the receiver, and the time last report has been
received from this locator.

Markers

By clicking on a marker, you can see marker-specific information, such
as APRS weather report shown below. The information bubble also
indicates marker’s name (e.g. HAM callsign), its distance from the
receiver, and the last time information has been received about this
marker. When relevant, OpenWebRX+ will also indicate the path information
travelled, as seen at the bottom of the information bubble.

Other Online Receivers

OpenWebRX+ will periodically query
ReceiverBook,
KiwiSDR, and
WebSDR.org
sites for other online SDR receivers. These receivers are indicated on
the map with ◬ markers, as shown below. Red markers stand
for KiwiSDR receivers, green markers correspond to OpenWebRX receivers,
while blue markers designate the original WebSDR receivers. Clicking on
a marker brings up the general information about the receiver, along
with a link to receiver’s web page.

Shortwave Stations

Once a day, OpenWebRX+ queries the
EiBi
database for shortwave broadcast schedules. Currently broadcasting
stations are indicated with ⍑ markers on the map, as shown
above. Clicking on a station brings up its schedule, with frequencies
and broadcast times. OpenWebRX+ will tune to clicked frequencies, as
long as they are within the profile you are listening to.

Repeaters

Once a day, OpenWebRX+ queries
RepeaterBook.com
for the list of repeaters closest to the receiver location. These
repeaters are indicated with ⋈ markers on the map, as
shown below.

Broadcast Radio

In this section, we will go over common radio broadcasting types and
how to use OpenWebRX to listen to the broadcast radio.

Listening to FM Broadcasts

What is FM broadcasting?

The FM broadcasts generally occur between 76MHz and 108MHz. Each
broadcaster is allocated 100kHz of spectrum, unless they are in the US
where 200kHz is allocated to each station. FM broadcasts may reach
distances up to 100km, limited by the horizon line. If you live in the
US, the closest FM stations can be found via the
Radio Locator
website.

In order to listen to FM broadcasts in OpenWebRX, select a profile
containing above frequencies, press the WFM
button at the receiver panel, and tune to one of the signals. Please
note that OpenWebRX only plays mono sound, so there will not be
any stereo.

OpenWebRX also allows to decode textual RDS information sent
within FM broadcasts, such as station name, program name and type, and
so on. If enabled, this information shows up in a box at the bottom of
the waterfall.

Since RDS data is encoded slightly differently in the US,
compared to Europe, you may want to go to «Settings | Demodulation
and Decoding | Miscellaneous» and change the «Decode USA-specific
RDS information from WFM broadcasts» option to reflect your receiver
location.

Listening to AM Broadcasts

What is AM broadcasting?

By «AM», people generally mean radio broadcasts occurring in the LW and
MW bands, between 100kHz and 1800kHz. Each station is allocated 10kHz of
the spectrum. During the day, AM broadcasts may reach up to 200km, but
this distance greatly increases during the night. If you live in the US,
the closest AM stations can be found via the
Radio Locator
website.

In order to listen to AM broadcasts in OpenWebRX, select a profile
containing above frequencies, press the AM
button at the receiver panel, and tune to one of the signals. If the
signal you are interested in is obscured by adjacent signals, try using
the SAM button instead. It has the same
effect as AM, but uses a different algorithm
more resistant to interference.

Shortwave Listening (SWL)

What is SWL?

«Shortwave» describes
multiple bands
between 1800kHz and 30MHz used by radio broadcasters, amateurs, and
professionals alike. The SWL activity generally refers to shortwave
broadcast listening though, with broadcasters easily reaching across
thousands of kilometers using AM modulation. Global shortwave broadcast
schedules can be found at the
Shortwave Info and
Shortwave Schedule
websites.

In order to listen to shortwave broadcasts in OpenWebRX, select a
profile containing the shortwave band you are interested in, press the
AM button at the receiver panel, and tune to
one of the signals. If the signal is obscured by adjacent signals, try
using the SAM button instead. It has the
same effect as AM, but uses a different
algorithm more resistant to interference.

Some shortwave broadcasters have started to use
Digital Radio Mondiale (DRM)
for their broadcasts. If you see a clearly digital signal at a shortwave
band, try tuning to it, pressing the DRM
button, and waiting 30-40 seconds for the decoder to sync. DRM
broadcasts are somewhat rare at the moment though.

Once a day, OpenWebRX+ queries the
EiBi
database for shortwave broadcast schedules. Currently broadcasting
stations are indicated with ⍑ markers on the map and
with bookmarks in the main receiver window.

HDRadio: Digital FM in America

What is HDRadio?

Many American FM broadcasters are now using a form of digital radio
known as HDRadio or NRSC5. The HDRadio signal, showing up
as two thick «columns» around a traditional WFM signal, adds up to four
digital channels to each analog FM broadcast.

HDRadio decoding requires a lot of CPU power and will not work on
slower computers, or wide profiles. In order to listen to HDRadio in
OpenWebRX+, tune to an «enhanced» WFM signal and click on the HDR button. Once the decoder syncs with the
signal, the station information and the channel selector should show up
at the bottom of the waterfall.

DAB: Digital FM in Europe

What is DAB?

Where American broadcasters use HDRadio, European FM broadcasters use a
different digital standard known as DAB. Each DAB multiplex
signal essentially occupies a single old analog TV channel and transmits
many individual radio station signals at once.

DAB decoding requires a lot of CPU power and will not work on slower
computers, or wide profiles. In order to listen to DAB in OpenWebRX,
tune to a DAB multiplex signal and click on the
DAB button. Once the decoder syncs up with
the signal, the station information and the station selector should show
up at the bottom of the waterfall.

Amateur Radio

This section discusses amateur (HAM) radio uses and how to use OpenWebRX
to listen to the amateur radio.

Listening to Citizens Band (CB)

What is CB?

Citizens Band (CB) generally covers a swath of spectrum between 27MHz
and 28MHz, where individuals can communicate without a license, as long
as they adhere to a few rules. The exact boundaries of the CB band
differ from country to country. It sits adjacent to the 10m amateur
band.

In most places, the CB band is divided into 40 channels (CB1 to CB40),
spaced at 10kHz. OpenWebRX+ provides default bookmarks for these
channels. While all analog voice modes (AM, FM, LSB, USB) were
originally allowed on CB, the US users generally prefer AM at lower
channels and LSB at upper channels. In the UK, where AM has been
banned until recently, FM is the most common CB mode.

In order to listen to CB in OpenWebRX, select a profile containing the
CB band and tune to one of the signals by clicking on the waterfall or
a bookmark. You may then have to press
AM, FM,
LSB, or USB
button at the receiver panel, depending on the modulation type used by
the transmission you are listening to.

Listening to HAM Bands

What is HAM?

The amateur radio operators (HAMs) are found at 160m, 80m, 40m, 20m, and
a few
other shortwave bands.
All kinds of activities happen at these bands, from Morse code, to
voice, to digital communications.

Each amateur band is usually broken into three parts:

The bottom part is used for the Morse code transmissions, also
known as «telegraph» or CW.

Right above the Morse code, there is a bunch of digital transmissions in
different modes, such as RTTY, FT8, FT4, and so on. A lot of these modes
operate at fixed frequencies, which are included into OpenWebRX band
plan and thus show up as green bookmarks.

The rest of a band is allocated for the voice (or «telephone»)
transmissions using LSB or USB modulation, with some AM sprinkled in.
The LSB modulation is used below 20m, while USB is used at 20m and
above.

In order to listen to amateur radio operators in OpenWebRX, select a
profile containing the HAM band you are interested in, press the
LSB or USB
button at the receiver panel and tune to one of the signals. While most
amateur transmissions occur at 1kHz boundaries, you may have to tune
more precisely to get cleaner sound.

Listening to Morse Code (CW)

What is CW?

Most Morse code (CW) transmissions occur at the lower end of amateur
radio bands, such as 3500-3600kHz, 7000-7100kHz, 14000-14100kHz, and
so on. To engage the CW mode in OpenWebRX, press the
CW button at the receiver panel. In this
mode, the bandpass filter shrinks to 700-900Hz range for better
selectivity. Also, when in CW mode, OpenWebRX+ will tune 800Hz
below clicked carrier frequency, to make sure that the carrier is
always heard.

For those who do not understand Morse code, OpenWebRX+ offers
automated CW decoding, enabled by selecting the «CW
Decoder» digital mode. The CW decoder presents you with a zoomed
secondary waterfall that may contain multiple CW signals. Once you click
on a CW signal you are interested in, the decoded text will show up
below the secondary waterfall, with unrecognized characters shown as
underscores.

You can also make the CW decoder show the original dits and dahs
it is decoding. To do that, go to «Settings | Demodulation and
Decoding | Miscellaneous» and enable the «Show CW codes (dits /
dahs) when decoding CW» option.

Finally, OpenWebRX+ can attempt decoding all CW transmissions in
24kHz of spectrum, at once, in real time, and present them to you in
a table, sorted by frequency. This functionality is enabled by selecting
the
«CW Skimmer» digital mode.

CW skimmer support requires installing the
CSDR CWSkimmer
package. Please, refer to «Settings | Feature Report» for further
instructions.

Receiving Teletype (RTTY)

What is RTTY?

A teletype transmission consists of two carrier signals, where one
signal designates «spaces» (or zeros), while the other signal designates
«marks» (or ones). Five bits in a row make a character, encoded with
Baudot code. Hence, there are three important parameters describing
an RTTY transmission:

Bandwidth (Hz)
This is the distance, in hertz, between two carrier signals. Common
bandwidths are 85Hz, 170Hz, 450Hz, and 650Hz.

Bitrate (baud)
This is the transmission speed, determining how many bits per second are
being sent. Common bitrates are 45bd, 45.45bd, 50bd, 75bd, and 100bd.

Reverse
The «reverse» option, when applied, flips the meanings of «space» and
«mark» frequencies.

OpenWebRX+ comes with three different RTTY settings, selected via
digital mode drop-down list:

RTTY-170 (45)
This is the mode commonly used by HAM operators, with 170Hz bandwidth
and 45bd bitrate. You can find transmissions in this mode just above
Morse code transmissions on most HAM HF bands.

RTTY-450 (50N)
This mode is used by the German weather service, most often found at the
10100kHz frequency. OpenWebRX+ includes default (yellow) bookmarks for
this and other German weather RTTY frequencies. This mode uses 450Hz
bandwidth and 50bd bitrate, with «mark» and «space» frequencies
reversed.

RTTY-85 (50N)
This mode is often used at the LF and VLF bands, where available
bandwidth is limited. It has 85Hz bandwidth and 50bd bitrate, with
«mark» and «space» frequencies reversed.

In order to receive a teletype transmission in OpenWebRX+, press the
USB button at the receiver panel and tune to
an RTTY transmission, which looks like two signals close together. Then
select one of the RTTY decoders described above. It will present you
with a zoomed secondary waterfall that may contain multiple RTTY
signals. Once you click on an RTTY signal you are interested in, the
decoded text will show up below the secondary waterfall, with
unrecognized characters shown as underscores.

Receiving SSTV Images

What is SSTV?

The slow scan television (SSTV) protocol lets radio amateurs exchange
small static images over airwaves. Most SSTV frequencies are listed in
the OpenWebRX+ band plan and will thus show up as green bookmarks. In
order to reliably receive SSTV images in OpenWebRX+, do the following:

Select «SSTV» digital mode and tune exactly 1900Hz below
the SSTV carrier frequency, or use any of the provided SSTV bookmarks.

Wait until the next SSTV transmission starts. OpenWebRX+ will not
receive partial SSTV transmissions since it needs to obtain the image
format information from the transmission header.

The received SSTV images will show up in a separate panel on top of the
waterfall display. Click on an image to download it to your computer or
mobile device.

OpenWebRX+ supports the following SSTV formats:

Robot12, Robot24, Robot36, and Robot72
Scottie1, Scottie2, Scottie3, Scottie4, and ScottieDX
PD50, PD90, PD120, PD160, PD180, PD240, PD290
Wraase SC2-30, SC2-60, SC2-120

Other SSTV formats, including digital SSTV, will not be received.

Tracking Packet Radio (APRS)

What is APRS?

The Automatic Packet Reporting System (APRS) lets HAM operators
exchange digital data, messages, and share their locations with the
world. The APRS uses 144.39MHz frequency in the North America, 144.8MHz
in Europe. Please note that the OpenWebRX band plan only has European
APRS frequency enabled. If your receiver is in the North America,
edit the band plan to switch to the 144.39MHz frequency.

In order to monitor APRS traffic in OpenWebRX, select «Packet»
digital mode and tune to one of the above frequencies. You will see
decoded APRS messages in a separate panel on top of the waterfall
display. Moreover, the sources of these messages will pop up at the
map, shown by clicking the Map button.

OpenWebRX+ band plan includes one more APRS entry, at 145.825MHz. This
is the International Space Station (ISS) frequency. Several times
a day, as ISS flies above the receiver location, you can expect to see
APRS reports from really far away at this frequency. These reports are
retransmitted by the APRS repeater located at the ISS.

Digital Communications

In this section, we are looking at digital radio transmissions that can
be heard and decoded with OpenWebRX.

Receiving Fax Images

What is radio fax?

Today, the HF radio fax protocol is mainly used to broadcast weather
maps and related information to vessels at sea. The US National Weather
Service regularly publishes
weather fax schedules
you can use to tune to a nearby fax broadcast. Also, OpenWebRX+ provides
default (yellow) bookmarks for most known weather fax frequencies. In
order to reliably receive a fax in OpenWebRX+, do the following:

Select «FAX» digital mode and tune exactly 1900Hz below
the fax carrier frequency, or use any of the provided fax bookmarks.

Wait until the next fax transmission starts. OpenWebRX+ will not
receive partial fax transmissions since it needs to obtain the image
format information from the transmission header.

The received fax images will show up in a separate panel on top of the
waterfall display. Click on an image to download it to your computer or
mobile device.

The fax decoder inside OpenWebRX+ supports 120LPM transmissions in
IOC576 and IOC288 formats. As an administrator, you have some
control over fax decoding. Following options are available in
«Settings | General | Demodulation and Decoding | Fax
Transmissions»:

Transmission speed
The transmission speed controls how many fax lines per minute the
decoder is going expect. The most common value is 120LPM. Do not
change it unless you are absolutely sure you need a different one.

Post-process received images to reduce noise
When enabled, this option makes fax decoder post-process received images
for better contrast. Some grayscale gradients may get lost as result
though.

Receive color images
This experimental option should allow OpenWebRX+ receive color faxes. It
has not been tested due to lack of samples though.

Use amplitude modulation
This experimental option lets OpenWebRX+ receive faxes encoded using AM
mode, rather than usual USB. So far, it has not been tested due to lack
of samples.

Monitoring Pager Messages (POCSAG)

What is a pager?

While mostly an outdated technology, wireless pagers are still in use at
hospitals, businesses, and for automated reporting. Pager traffic is
commonly found at 150-165MHz, as well as other VHF and UHF bands.
OpenWebRX+ can decode both
POCSAG and
FLEX
paging protocols at different speeds.

Keep in mind that your local laws may prohibit you from listening to
the pager traffic. Please, check before you do!

In order to monitor pager messages in OpenWebRX+, select «Page»
digital mode and tune to the exact middle of a pager signal. You will
see decoded pager messages in a separate panel on top of the waterfall
display.

A lot of pager messages carry numeric or binary data. As an
administrator, you can choose to ignore these unreadable messages
by going to «Settings | General | Demodulation and Decoding |
Miscellaneous» and enabling the «Filter out empty, numeric, or
unreadable pager messages» option.

Monitoring Wireless Devices (ISM)

What is ISM?

Many modern wireless devices, such as weather stations, security
sensors, tire pressure sensors, car keys, etc., use radio frequencies to
communicate. These devices are normally found in 433-435MHz, 902-928MHz,
and some other bands. In order to monitor smart device transmissions in
OpenWebRX+, do the following:

Look around ISM frequencies for signals that may be produced by wireless
devices.

Once you see any suspicious signals, tune near them and select the
«ISM» digital mode. The ISM decoder will monitor and display a
wide swath of spectrum around your tuned frequency.

Wait until the signals reappear. If the ISM decoder is able to
understand them, the decoded data will appear in a separate panel on top
of the waterfall display.

If you are unable to decode any ISM signals or do not see any on the
waterfall, try testing the decoder with your wireless car keys.
It is important to know their signalling frequency though.

Aeronautic Communications

Most voice communications between pilots and air traffic controllers
occur in the specially designated 108-137MHz VHF «air band». Somewhat
unusual for VHF bands, aircraft use AM modulation to let multiple
signals be heard at once at the same frequency. On the shortwave bands,
you will find aeronautic weather reports (VOLMET) and some pilot chatter
using USB modulation.

In addition to analog voice communications, aircraft and air traffic
control services use several digital radio protocols for
location reporting,
telemetry,
messaging, and
traffic management.
With sufficient hardware, OpenWebRX+ can receive multiple aeronautic
protocols at multiple frequencies at once, maintaining a common database
of all received aircraft data and presenting it on the map.

Aircraft are identified with several different IDs, including flight ID,
aircraft tail number, and ICAO code (aka Mode-S transponder code).
OpenWebRX+ will hyperlink received IDs to the
FlightAware
website, where you can find flight paths, photos, and other facts about
each flight.

Tracking Airplanes (ADS-B)

What is ADS-B?

Airplanes periodically report their locations using the Automatic
Dependent Surveillance Broadcast (ADS-B) system, at 1090MHz and
978MHz frequencies. OpenWebRX+ can listen to these frequencies and
display received flight information to you.

To receive ADS-B transmissions, select a profile containing one of the
ADS-B frequencies. Since these transmissions require 2.4MHz of
bandwidth, the profile must have at least 1.2MHz of bandwidth at each
side of an ADS-B frequency.

Standard ADS-B frequencies are part of the OpenWebRX+ band plan and thus
marked with green bookmarks. Once you click on an ADS-B bookmark, a
panel will appear showing the reported aircraft with their flight data.

If you click on the Map button, you should
see aircraft locations on the map. Clicking on an airplane pops up a
bubble showing some basic information about that airplane.

Long Range Communications (HFDL)

What is HFDL?

The HF Data Link (HFDL) is a long-distance shortwave messaging
system used to manage aircraft traffic around the globe. The system
consists of around 15 ground stations (GS) covering the entire globe.
HFDL messages may contain aircraft locations, telemetry, and text
communications between ground stations and the aircraft.

All HFDL ground station frequencies are marked with yellow bookmarks in
OpenWebRX+. Simply click on a bookmark to start receiving HFDL messages,
or tune manually and select the «HFDL» digital mode.

Keep in mind that you will not be able to hear all the ground stations
from a single location: that is why there are multiple stations all
around the globe. Also, each ground station has its own broadcasting
schedule and thus may be silent at the present time.

If you click on the Map button, you should
see HFDL-reported aircraft locations as little
green airplanes on the map. Clicking on an
airplane pops up a bubble showing some basic information about that
airplane. Since HFDL does not report aircraft altitude or direction,
most airplanes will be pointing north. If OpenWebRX+ receives more than
one HFDL position report though, it will orient airplane based on the
difference between the last two reports.

Short Range Communications (VDL2)

What is VDL2?

The VHF Data Link Mode 2 (VDL2) is an air band (VHF) messaging
system aircraft use to communicate with the air traffic control within
their line of sight. VDL2 messages may contain aircraft locations,
telemetry, and text communications between aircraft and local ground
control.

VDL2 frequencies are found at the end of the air band (108-137MHz) and
marked with yellow bookmarks in OpenWebRX+. These bookmarks are commonly
labelled with «ARINC» or «SITA», depending on the company
that manages each frequency. Simply click on a bookmark to start
receiving VDL2 messages, or tune manually and select the «VDL2»
digital mode.

Keep in mind that not all VDL2 frequencies will appear live from your
receiver location: some of them are only used in certain parts of the
world.

If you click on the Map button, you should
see VDL2-reported aircraft locations as little
blue airplanes on the map. Clicking on an
airplane pops up a bubble showing some basic information about that
airplane, including text message history. Since VDL2 does not report
aircraft direction, most airplanes will be pointing north. If OpenWebRX+
receives more than one VDL2 position report though, it will orient
airplane based on the difference between last two reports.

Legacy Communications (ACARS)

What is ACARS?

The Aircraft Communications Addressing and Reporting System
(ACARS) is the original aircraft communications protocol, now mostly
replaced with VDL2. Similarly to VDL2, ACARS uses the air band to carry
telemetry and text messages between aircraft and local air traffic
control. Unlike VDL2, ACARS messages rarely contain aircraft locations.

ACARS frequencies are found at the end of the air band (108-137MHz) and
marked with yellow bookmarks in OpenWebRX+. Simply click on a bookmark
to start receiving ACARS messages, or tune manually and select the
«ACARS» digital mode.

Keep in mind that not all ACARS frequencies will appear live from your
receiver location: some of them are only used in certain parts of the
world, others replaced with VDL2.

If you click on the Map button, you might
see some ACARS-reported aircraft locations as little
red airplanes on the map. Clicking on an
airplane pops up a bubble showing some basic information about that
airplane, including text message history. Since ACARS does not report
aircraft direction, most airplanes will be pointing north. If OpenWebRX+
receives more than one ACARS position report though, it will orient
airplane based on the difference between last two reports.

Maritime Communications

Vessels at sea use shortwave bands and USB modulation for voice
communications over long distances. Short range voice calls between
ships and the shore occur in the 156-174MHz VHF «marine band». In
addition to analog voice, the marine band contains
AIS location reporting,
paging, and other digital services.

A lot of digital maritime communications fall under the
Global Maritime Distress and Safety System (GMDSS),
which includes
marine safety information (MSI),
navigational telex (NAVTEX), and
digital selective calling (DSC).
Marine weather maps are available via
weather fax transmissions from coastal stations.

Tracking Ships (AIS)

What is AIS?

Modern vessels report their locations using a VHF radio system known as
Automatic Identification System (AIS). If your OpenWebRX+
receiver is located near a large enough body of water, it may be able to
receive AIS position reports and display them on the map.

AIS operates at two marine band frequencies, 161.975MHz and 162.025MHz.
Once you select a profile containing these frequencies, you will see
them marked with green bookmarks, since they are part of the band plan.
Click on an «AIS» bookmark and a secondary waterfall should appear,
together with the information panel showing received position reports.

Now, if you click on the Map button, you
should see ship locations on the map. Clicking on a ship pops up a
bubble showing some basic information about that ship.

AIS identifies every vessel with a unique number known as MMSI.
OpenWebRX+ shows these MMSI numbers, hyperlinking them to the
Vessel Finder
website, where you can find photos and other facts about each vessel.

Maritime Safety Information (MSI)

What is MSI?

The Maritime Safety Information (MSI) messages are distributed
on shortwave bands using SITOR-B protocol. The SITOR-B is somewhat
similar to RTTY, but adds redundancy and error
checking.

Standard MSI frequencies are marked with yellow «MSI» bookmarks in
OpenWebRX+. Simply click on a bookmark to start receiving MSI messages,
or tune manually and select the «SITOR-B» digital mode.

Navigational Telex (NAVTEX)

What is NAVTEX?

Similar to MSI, Navigational Telex (NAVTEX) uses SITOR-B
protocol. Coastal stations send regular NAVTEX bulletins at prearranged
shortwave frequencies. Each NAVTEX bulletin starts with a four-letter
code specifying its origin, subject, and sequential number.

Standard NAVTEX frequencies are part of the OpenWebRX+ band plan and
thus marked with green «NAVTEX» bookmarks. Simply click on a bookmark to
start receiving NAVTEX messages, or tune manually and select the
«NAVTEX» digital mode. Same NAVTEX transmissions can be received
by selecting the «SITOR-B» digital mode, but OpenWebRX+ will not
be able to check for the four-letter bulletin identifiers when using
plain SITOR-B.

Digital Selective Calling (DSC)

What is DSC?

Digital Selective Calling (DSC) uses predefined digital messages
to report emergencies and other special events, as well as announce
voice call frequencies. DSC operates in shortwave and marine (VHF)
bands, but OpenWebRX+ is only able to decode shortwave DSC modes at the
moment. In addition to sender’s and receiver’s MMSIs, DSC messages may
also carry their positions. For emergencies, the nature and location of
emergency are reported.

Standard DSC frequencies are marked with yellow bookmarks in OpenWebRX+.
Simply click on a bookmark to start receiving DSC messages, or tune
manually and select the «DSC» digital mode.

Installing OpenWebRX+

This section provides step by step instructions for installing
OpenWebRX+. There are prebuilt OpenWebRX+ packages for
Ubuntu 22.04,
Ubuntu 24.04,
Debian Bullseye, and
Debian Bookworm.
There are also pre-built
SD card images for Raspberry Pi
users, as well as
Docker images.
If you are running a different version of Linux and have sufficient
experience, you can try
compiling OpenWebRX+ from sources.

Installing on Ubuntu 22.04

Start by adding the OpenWebRX+ repository, as well as the original
OpenWebRX repository. You will be asked to enter your Linux user
password:

curl -s https://luarvique.github.io/ppa/openwebrx-plus.gpg | sudo gpg –yes –dearmor -o /etc/apt/trusted.gpg.d/openwebrx-plus.gpg
sudo tee /etc/apt/sources.list.d/openwebrx-plus.list

Once the repositories are added,
install OpenWebRX+ from packages.

Installing on Ubuntu 24.04

Start by adding the OpenWebRX+ repository, entering your Linux user
password when asked:

curl -s https://luarvique.github.io/ppa/openwebrx-plus.gpg | sudo gpg –yes –dearmor -o /etc/apt/trusted.gpg.d/openwebrx-plus.gpg
sudo tee /etc/apt/sources.list.d/openwebrx-plus.list

Once the repository is added,
install OpenWebRX+ from packages.

Installing on Debian Bullseye

Start by adding the OpenWebRX+ repository, as well as the original
OpenWebRX repository. You will be asked to enter your Linux user
password:

curl -s https://luarvique.github.io/ppa/openwebrx-plus.gpg | sudo gpg –dearmor -o /etc/apt/trusted.gpg.d/openwebrx-plus.gpg
sudo tee /etc/apt/sources.list.d/openwebrx-plus.list

Once the repositories are added,
install OpenWebRX+ from packages.

Installing on Debian Bookworm

Start by adding the OpenWebRX+ repository, entering your Linux user
password when asked:

curl -s https://luarvique.github.io/ppa/openwebrx-plus.gpg | sudo gpg –yes –dearmor -o /etc/apt/trusted.gpg.d/openwebrx-plus.gpg
sudo tee /etc/apt/sources.list.d/openwebrx-plus.list

Once the repository is added,
install OpenWebRX+ from packages.

Installing from Packages

Once you have all required package repositories added, install
OpenWebRX+ as follows:

sudo apt update
sudo apt install openwebrx

If you already have an older version of OpenWebRX installed, do this
instead:

sudo apt update
sudo apt upgrade

To make sure OpenWebRX+ is running, direct your local web browser to the
following address and see if OpenWebRX+ web interface shows up there:

http://localhost:8073/

Using Raspberry Pi SD Images

If you have a Raspberry Pi, you can use
pre-built SD card images
containing a clean OpenWebRX+ installation with all the optional
packages. The 32bit image should run on all devices except for RPI1 and
RPI5. The 64bit image should run on all devices except for RPI1, RPI2,
and RPIZero1. Both images support common SDR device models out of the
box. For example, both RTL-SDR and SDRPlay devices have been confirmed
to work with no additional modifications to the images.

To flash image to an SD card, run
Raspberry Pi Imager
and select «USE CUSTOM» option from the «Operating System |
CHOOSE OS» menu. Prior to flashing SD card, you can tell RPI
Imager to set up the root password. If you skip this step, you will
be asked to create root password on the first startup.

After booting the image, you will have to SSH into the device using your
username and password from the installation. Follow the instructions on
the console to create your admin account for OpenWebRX+.
Use the admin account to log in to the OpenWebRX+ Settings interface
and setup your receiver.

Please note that these images come without the software support for
digital modes (DMR, NXDN, etc), since the software decoder for these
modes (mbelib) has questionable origins. In order to enable digital
modes in these images, ssh into the user account you created while
installing the image and type:

sudo install-softmbe.sh

Using Docker Images

IMPORTANT: Docker images will not work on Windows OS. Windows
does not allow Docker access to USB devices. You will have to run Docker
on Linux.

Pre-built Docker images contain clean OpenWebRX+ installation with all
the optional packages. There are two Docker images, both supporting
x86-64, ARM64, and ARM32 architectures, one
with SoftMBE
and another
without SoftMBE.
The easiest way to use OpenWebRX+ Docker image is through
Docker Compose,
as shown below:

Install Docker and Docker Compose. The exact procedure
depends on your Linux distribution. You will need to research that by
yourself.

Create folders to store your persistent data (settings,
profiles, plugins, etc.). Here, we will use «/opt/owrx-docker» as
the base folder to store all our data, but you can also use a different
folder:

sudo mkdir -p /opt/owrx-docker/var /opt/owrx-docker/etc /opt/owrx-docker/plugins/{receiver,map}

Create «docker-compose.yaml» file as shown below.
You can save this file to the «/opt/owrx-docker» folder and
modify it to your needs. Configure TZ, ADMIN_USER, and ADMIN_PASS
variables, using
canonical identifier
for TZ. If you are using data folder different from
«/opt/owrx-docker», modify your «docker-compose.yaml» file
to reflect that. Keep in mind that YAML files are indented with spaces,
and the spaces in front of each line are important.

services:
owrx:
image: ‘slechev/openwebrxplus-softmbe:latest’
container_name: owrx-mbe
restart: unless-stopped
ports:
– ‘8073:8073’
environment:
TZ: Europe/Sofia
OPENWEBRX_ADMIN_USER: myuser
OPENWEBRX_ADMIN_PASSWORD: password
devices:
– /dev/bus/usb:/dev/bus/usb
volumes:
– /opt/owrx-docker/etc:/etc/openwebrx
– /opt/owrx-docker/var:/var/lib/openwebrx
– /opt/owrx-docker/plugins:/usr/lib/python3/dist-packages/htdocs/plugins
# mount /tmp in memory, for RPi devices, to avoid SD card wear and make dump1090 work faster
tmpfs:
– /tmp:mode=1777

Start the container as follows:

cd /opt/owrx-docker && sudo docker compose up -d

To update your container to the latest released image, use:

cd /opt/owrx-docker && sudo docker compose pull && sudo docker compose down && docker compose up -d

More information about environment variables within the image and how to
use docker-cli method can be found at the
Docker Hub Page.

IMPORTANT: If you are using SDRPlay devices with Docker,
restart the container every time you reboot the host or reconnect a
device. Docker will not present a «new» SDRPlay device to the
container unless that container is restarted.

Compiling OpenWebRX+ from Sources

Please, do not attempt building OpenWebRX+ from sources, unless you
know exactly what you are doing! If you feel confident enough
though, and have a Debian-like Linux, start by cloning OpenWebRX+
repository and running the «buildall.sh» script as follows:

git clone https://github.com/luarvique/openwebrx.git
cd openwebrx
./buildall.sh

The script will attempt to fetch and build all OpenWebRX+ dependencies
prior to building OpenWebRX+ itself. It will also build a bunch of
optional packages. The build process uses the «owrx-build» folder
to store intermediate files. The final .deb packages will be
deposited into the «owrx-output» folder.

If the build breaks, it is up to you to find and fix the cause.
It is expected that you know how to find and rectify build issues. Once
the build successfully finishes, you can install the freshly built
packages as follows:

sudo dpkg -i ./owrx-output/*.deb

Hardware Setup

OpenWebRX supports multiple SDR receiver devices at the same time. The
total number is mainly limited by your computer performance. In this
section, we are going to discuss the most common SDR devices, their
capabilities, and how to set them up with OpenWebRX. Here is a short
comparison of the most common SDR devices:

Device
Range
Bandwidth
Resolution
Interface

RTLSDRv3
500kHz-14MHz, 24MHz-1766MHz
2.4Msps
8bit
USB

RTLSDRv4
500kHz-1766MHz
2.4Msps
8bit
USB

SDRPlay
1kHz-2000MHz
≤ 10Msps
≤ 14bit
USB

Airspy R2
24MHz-1700MHz
10Msps
12bit
USB

Airspy HF+
500Hz-31MHz, 64MHz-260MHz
768ksps
18bit
USB

Hermes Lite 2
130kHz-30MHz
4 x 384ksps
12bit
Ethernet

HackRF One
1MHz-6GHz
20Msps
8bit
USB

See below for instructions on making these SDR devices work with
OpenWebRX.

RTL-SDR Devices

RTL-SDR is a large family of USB-connected SDR receivers based on the
Realtek RTL2832U chipset. Under regular circumstances, these
devices allow reception in the 24MHz-1766MHz range. They can also be
persuaded to work in the 500kHz-14MHz range, although the reception
quality is not very good there.

RTLSDRv3

The most common RTL-SDR device is
RTLSDRv3 from
RTL-SDR Blog.
In a lot of cases, the driver for this device is already installed in
your Linux system. If it is not, you can install it with the following
command:

sudo apt install rtl-sdr librtlsdr0 librtlsdr-dev

RTLSDRv4

A somewhat better RTL-SDR version is
RTLSDRv4 from
RTL-SDR Blog.
This device officially supports the 500kHz-24MHz frequency range via the
built-in transverter. It may require updated RTL-SDR drivers though. If
your current drivers do not support RTLSDRv4, you may have to
build and install the new drivers as follows:

sudo apt install libusb-1.0-0-dev git cmake build-essential pkg-config debhelper
git clone https://github.com/rtlsdrblog/rtl-sdr-blog
cd rtl-sdr-blog
sudo dpkg-buildpackage -b –no-sign
cd ..
sudo dpkg -i librtlsdr0_.deb librtlsdr-dev_.deb rtl-sdr_*.deb

Receiving Shortwave Frequencies with RTL-SDR

With RTLSDRv4 devices, you do not need to do anything special in order
to use the 500kHz-24MHz frequency range. These frequencies will work out
of the box, as long as you are using the correct device driver.

With RTLSDRv3 and similar devices, you will have to add the «Direct
Sampling» option to each shortwave profile and set its value to
«Direct Sampling (Q branch)». With this option enabled, most
RTL-SDR devices will be able to receive in the 500kHz-14MHz range. The
14MHz-24MHz range will remain unusable.

Please, note that the default RTLSDR device entry in OpenWebRX has been
created for RTLSDRv3, so all profiles under that entry have the
«Direct Sampling» option enabled. If you happen to have
RTLSDRv4, make sure to remove the direct sampling option from every
RTLSDR profile. Otherwise, these profiles will not work.

Connecting Multiple RTL-SDR Devices

When using multiple RTL-SDR devices with OpenWebRX, you will have to
assign each of them a unique serial number with the following shell
command:

rtl_eeprom -d <device-index> -s <serial-number>

Once assigned, the serial number will be persistently stored within
each device. To make OpenWebRX distinguish between your devices, add
the «Device Identifier» option to each device and set it to
device’s unique serial number.

To see indices and serial numbers of your RTL-SDR devices, run the same
command without arguments:

rtl_eeprom

SDRPlay (RSP) Devices

RSP is a family of USB-connected SDR receivers based on the Mirics
MSI001 / MSI2500 chipset. The official RSP devices are made and sold
by
SDRPlay,
but since the basic schematics are standard, there are many inferior,
but cheaper Chinese RSP clones on the market. These devices are capable
of continuous reception in the 0-2GHz range, with bandwidth of up to
6Msps. This bandwidth can be further widened to 10Msps at the cost of
losing some bit resolution.

Making RSP Device Work with OpenWebRX+

To make an RSP device work with OpenWebRX+, you will first have to
download and install the latest SDRPlay API for your version of
Linux from the
SDRPlay website.
Your RSP device will not work unless you install the SDRPlay API.

Once you have SDRPlay API installed, install the SoapySDRPlay3 package
from OpenWebRX+ repositories as follows:

sudo apt install soapysdr-module-sdrplay3

During installation, the SoapySDRPlay3 package will also install the
latest SoapySDR and remove all locally built SoapySDR files from
/usr/local to prevent conflicts between packaged and locally
built versions of SoapySDR.

Solving SDRPlay API Problems

You may encounter a situation where installed SDRPlay API breaks down
on your Linux system due to incompatible system libraries. If you look
at the SDRPlay service logs:

journalctl -u sdrplay

and see the following messages:

/opt/sdrplay_api/sdrplay_apiService:
/lib/arm-linux-gnueabihf/libc.so.6: version `GLIBC_2.34′ not found
(required by /opt/sdrplay_api/sdrplay_apiService)

then the only way to fix it is to downgrade to an older version of the
SDRPlay API. Install SDRPlay API v3.07 from the
SDRPlay website,
then downgrade SoapySDRPlay3 to a compatible version and prevent it from
further upgrades:

sudo apt install soapysdr-module-sdrplay3=0.8.6
sudo apt-mark hold soapysdr-module-sdrplay3

Connecting Multiple RSP Devices

Each genuine RSP device has a unique serial number assigned at the
factory. You can see these serial numbers with the following command:

sudo SoapySDRUtil –probe=»driver=sdrplay»

To make OpenWebRX distinguish between your devices, add the «Device
Identifier» option to each device and set it to device’s unique
serial number.

The Chinese-made RSP clones all come with the same serial number and
thus only one Chinese RSP clone can be used with the SDRPlay API.
A workaround to this problem is to downgrade SDRPlay API to v3.07 and
install the corresponding SoapySDRPlay3 package version, since older
SDRPlay API uses USB port numbers as serial numbers. Install SDRPlay API
v3.07 from the
SDRPlay website,
then downgrade SoapySDRPlay3 to a compatible version and prevent it from
further upgrades:

sudo apt install soapysdr-module-sdrplay3=0.8.6
sudo apt-mark hold soapysdr-module-sdrplay3

Airspy Devices

Airspy is a family of USB-connected SDR receivers based on the
Realtek R820T2 chipset. These devices are made and sold by
Airspy.

Airspy R2 and Airspy Mini

Most Linux distributions will have
Airspy R2 and
Airspy Mini
drivers installed by default. If this is not the case, you can install
the drivers as follows:

sudo apt install soapysdr-module-airspy

Airspy HF+

The Airspy HF+
does not have a packaged driver yet, so you will need to compile it as
follows:

sudo apt install libusb-1.0-0-dev git cmake build-essential pkg-config debhelper libairspyhf-dev
git clone https://github.com/pothosware/SoapyAirspyHF.git
cd SoapyAirspyHF
sed -i ‘s/soapysdr0.7-module/soapysdr0.8-module/’ debian/control
mv debian/soapysdr0.{7,8}-module-airspyhf.install
sudo dpkg-buildpackage -b –no-sign
cd ..
dpkg -i soapysdr0.8-module-airspyhf_.deb soapysdr-module-airspyhf_.deb

Hermes Lite 2

Hermes Lite 2 (HL2) is a hobbyist-designed SDR transceiver based on high
performance ADC and FPGA chips. Transmit capability aside, HL2 can
receive up to four independent chunks of spectrum in the 0-30MHz range,
with each chunk limited to the 384kHz width. This makes HL2 ideal for
monitoring multiple shortwave bands at the same time.

Making HL2 Work with OpenWebRX+

To make HL2 work with OpenWebRX+, you will have to connect HL2 to your
OpenWebRX+ computer with an Ethernet cable. Once HL2 is connected and
powered up, it will eventually assign itself the «local» IP address of
169.254.19.221. You then need to install the HPSDR Connector
package from OpenWebRX+ repositories, as follows:

sudo apt install hpsdrconnector

Once installed, you should be able to add new HPSDR devices in the
OpenWebRX+ settings. When adding an HPSDR device, make sure you add the
«Remote IP» option and set it to the default HL2 IP address of
169.254.19.221.

Adding Multiple HPSDR Devices

As has been said before, your HL2 can receive up to four distinct chunks
of the shortwave spectrum, representing each chunk with a separate
virtual «device». To make use of this capability though, you will have
to add four separate HPSDR devices to OpenWebRX+. Point all four devices
to the same IP address. Make sure all HPSDR devices use the same
sampling rate, as HL2 runs all its RX channels at the same rate.

HackRF One

HackRF One is an open source, USB-connected SDR. In most cases, HackRF
One drivers should already be present in your system. If this is not the
case, install the drivers as follows:

sudo apt install soapysdr-module-hackrf

Choosing an Antenna

It is recommended to connect antenna via a shielded cable in order to
keep it away from the receiver and other interference sources. Possible
interference sources include power supplies, phone chargers, LED lights,
refrigerators, air conditioners, water pumps, and other devices. Power
lines inside your home may carry this interference all over the place.
Also, powerline network adapters are especially bad sources of electric
noise, so avoid using them.

Your antenna choice will always depend on the frequencies you would like
to receive and the amount of radio interference at your location. In
this section, we will go over some available options.

Telescopic Antennas

A telescopic antenna is going to be resonant (most sensitive) to
wavelengths that are twice the antenna length. Their limited length
makes telescopic antennas the best at FM, VHF, and UHF bands. These
antennas can be used for shortwave (<30MHz) reception, but are
not very good there.

All telescopic antennas work the same, with longer antennas being more
sensitive at lower frequencies. More expensive telescopic antennas are
made of sturdier materials and offer better articulation, but not better
reception. CB telescopic antennas are a special case, since they
contain circuitry biasing them in favor of the CB band.

Grounding the receiver will improve antenna performance. Also, a
telescopic dipole («TV whiskers») will have better performance than a
single whip, since it has bigger total length and does not require
grounding.

Long Wire Antennas (LW, MW, SW)

The optimal length of an antenna should be close to 1/2 of the
wavelength you expect to receive. For example, if you are planning to
listen to the 25m shortwave band, the optimal antenna length will be 25
/ 2 ≈ 12.5 meters, which makes shortwave telescopic antennas
rather difficult to implement. It is still possible though to attach a
really long wire to the antenna connector, throwing it outside or
wrapping it around a room as necessary.

Grounding the receiver will improve antenna performance. Also, a dipole
made of two pieces of wire will have better performance than a single
wire, since it has bigger total length and does not require grounding.

Rubber Whip Antennas (VHF, UHF)

At shorter wavelengths (80MHz+), it is possible to use short rubber whip
antennas made for the use in walkie talkies, first responder radios, and
scanners. These antennas are small, very portable, and offer decent
reception in the FM, VHF, and UHF bands. It is necessary to say though
that these antennas are specifically tuned for the VHF and UHF
bands and thus become useless in the LW, MW, and SW bands.

Non-Resonant Loop Antennas

As said before, the electromagnetic interference is often a huge problem
when listening to the radio indoors or in urban environment. The
magnetic loop antennas attempt to work around this interference by
receiving the magnetic component of the wave rather than the noisier
electric component.

A typical non-resonant loop antenna consists of one or more relatively
small (≈1m in diameter) loops of wire connected to a
receiver via a tiny transformer («balun» or «unun»). The total surface
of the wire loop determines how much magnetic flux it receives, making
bigger loops more sensitive. A loop antenna is directional:

At the wavelengths much longer than the loop size (LW, MW, SW),
the maximum gain is achieved when a side of the loop is directed towards
the signal source. The loop is not resonant at these frequencies,
i.e. it does not favor any specific frequency.

At the wavelengths comparable to the loop size (FM, VHF, UHF),
the maximum gain is achieved when the loop surface is directed towards
the signal source, same as if it were a dipole. The loop becomes
resonant at these frequencies.

While loop antennas are less susceptible to electromagnetic interference,
they are also less sensitive to the actual signals. Thus, many
commercial loop antennas include low-noise amplifiers (LNAs),
requiring a power source. If your loop antenna does not have an LNA,
consider adding one. Some commercially available loop antennas are
YouLoop, MLA-30+, and GA-450.

MiniWhip Antennas

A MiniWhip is an active antenna made of a small metal plate («probe»)
and a low-noise amplifier (LNA). It measures the electric field strength
at the probe, making it a tiny receive-only antenna for a wide range of
frequencies.

Being an active antenna, MiniWhip does require a power source. Also,
since MiniWhip is essentially a non-resonant electric field probe, it is
highly susceptible to interference. Thus, you will need to install it in
an area free of electromagnetic noise.

Administrator Features

This section discusses administering an OpenWebRX server and how it can
be used besides providing public access to radio waves.

Background Decoding

As a server administrator, you can make OpenWebRX server
automatically decode radio transmissions when someone is
listening to a profile with these transmissions. This feature can be
used to receive SSTV images, faxes, monitor digital HAM traffic, track
airplanes, and so forth.

To start with background decoding, go to «Settings | Background
Decoding», check the «Enable background decoding services»
option, and select transmission modes you would like to receive and
decode automatically. Make sure you only select the ones you really
need, since running too many background decoders will slow your server
down, a lot.

Now, go to an SDR device you want to use for background decoding, let us
say «Settings | SDR Devices and Profiles | <Device>», and
add the «Run background services on this device» option. Once you
have added this option, make sure it is enabled.

At this point, every time someone connects and listens to a
<Device> profile, OpenWebRX will automatically decode
all enabled signal types at frequencies marked with green bookmarks,
i.e. everything that is part of the band plan. If the decoded data is an
image or a message log, these will be saved to the /tmp folder
and shown once you click the Files button.
Location reports, such as FT8, WSPR, APRS, and others, will show up on
the map, when you click the Map button.

In order to enable background decoding at a frequency that is not
part of the band plan (no green bookmark), you will have to add
that frequency to the band plan by editing the following file:

sudo nano /etc/openwebrx/bands.json

There are also region-specific band plan files in the same folder. If
you have selected a region-specific band plan in «Settings |
General», edit that band plan instead. Prior to editing a band
plan file, make sure you create a backup copy, in case something
goes wrong. After editing and saving the file, restart OpenWebRX as
follows and make sure there is a green bookmark at the frequency you
added:

sudo systemctl restart openwebrx

A typical bands.json frequency entry will look as follows:

«frequencies»: {
«<mode>»: <frequency>,
…
}

The background decoding in OpenWebRX+ supports the following modes:

«ft8», «wspr», «jt65», «jt9», «ft4», «fst4», «fst4w», «q65», «msk144»,
«js8», «packet», «ais», «sstv», «fax», «navtex», «dsc», «page», «eas»,
«ism», «hfdl», «vdl2», «acars», «adsb», «audio».

If you have multiple frequencies associated with the same mode,
enter them as a list:

«frequencies»: {
«<mode>»: [ <frequency1>, <frequency2>, … ],
…
}

Finally, if you would like to specify an underlying modulation, such as
«lsb», «usb», «am», «nfm», «sam», or
«cw», enter it as follows:

«frequencies»: {
«<mode>»: { «frequency»: <frequency>, «underlying»: «<modulation>» },
…
}

Here is an example of two FT4 frequencies, using their default USB
modulation, and two SSTV frequencies using different modulations:

«frequencies»: {
«ft4»: [ 3568000, 3575000 ],
«sstv»: [
{ «frequency»: 3730000, «underlying»: «lsb» },
{ «frequency»: 3845000, «underlying»: «usb» }
],
…
}

Here is another example of an FM-modulated VHF frequency. With the
«Settings | Background Decoding | Audio Recorder» option enabled,
this entry will make OpenWebRX+ record audio to an MP3 file and let
users access it via the file browser page:

«frequencies»: {
«audio»: { «frequency»: 145700000, «underlying»: «nfm» },
…
}

Scheduled Decoding

In the previous section, we discussed how
OpenWebRX can decode radio transmissions automatically, while someone is
using it. In this section, we are going to make OpenWebRX run the
radio and receive signals on its own, when nobody is using it.

Start with an SDR device where you previously enabled background
services by going to «Settings | SDR Devices and Profiles |
<Device>». Add the «Scheduler» option to this device
and find the newly added scheduler selector among other settings.
It is going to offer you two different schedule models:

Daylight Scheduler
The daylight scheduler lets you select three profiles to run on the
device during the day, the night, and the «greyline» period (i.e. dawn
and dusk). Since radio waves propagation depends on the time of a day,
this scheme provides easy to configure, yet functional schedule.

Static Scheduler
The static scheduler lets you define your own schedule of as many
entries as you like, with minute precision. While such a schedule is
more difficult to add, it gives you flexibility to switch through
several different profiles each hour.

Once you have your schedule added and saved, OpenWebRX will switch
device between scheduled profiles, as long as nobody is using this
device. Once all the users disconnect, OpenWebRX will return the SDR
device to its currently scheduled profile. It will also run any
applicable background decoders you enabled earlier, reporting received
data to the map or saving it to the file storage.

Reporting Decoded Data

In the
two previous
sections, we discussed how OpenWebRX can be configured to automatically
decode various radio transmissions. In this section, we are going to
discuss sending the decoded data to online services, such as
APRS-IS,
PSKReporter,
WSPRnet, or
MQTT.
To configure online reporting, go to the «Settings | Spotting and
Reporting» settings page. There are three sections there, for the
three types of data OpenWebRX can report:

APRS-IS
The received APRS position reports can be sent to the
APRS-IS network.
In order to do that, fill in your APRS callsign and the nearest server
address. You may also need to provide APRS-IS network password. Finally,
check the «Send received APRS data to APRS-IS» option. The
reported data will show up at the
APRS.fi map.
Please, note that
APRS.fi
does not show multiply reported spots, so some of your reports may not
show there.

If you would also like to report your receiver position to
APRS-IS, check the «Send the receiver position to the APRS-IS
network» option and fill in information about your receiver and
antenna specifics.

Please, note that only one decoder can send data to the APRS-IS
network using the same callsign. Thus, if you have more than one
APRS decoder running (for example, at 144.39MHz and 145.825MHz), some of
your reports will not make it through. To fix this issue, disable all
but one APRS frequency in the band plan file.

PSKReporter
OpenWebRX can report FT8, FT4, JT9, JT65, FST4, JS8, Q65, WSPR, FST4W,
and MSK144 transmissions to the
PSKReporter
website. All you need to do is check the «Enable sending spots to
pskreporter.info» option and fill callsign field with a unique name.
It does not have to be your official HAM callsign, but most
people who have HAM callsigns use them here. The reported data will show
up at the
PSKReporter map.
You may also want to describe your antenna in the antenna information
field, so that other people know how you received the data you are
reporting.

WSPRnet
The
WSPRnet
website only accepts WSPR and FST4W reports. To enable it, check the
«Enable sending spots to wsprnet.org» option and enter your
unique name into the callsign field. It does not have to be your
official HAM callsign, but most people who have HAM callsigns use them
here. The reported data will show up at the
WSPRnet map.

MQTT
The
MQTT
is a protocol for reporting IOT events to multiple remote subscribers.
In order to use MQTT, you will need to have an MQTT broker, such as
Mosquitto.
Once you have a broker, enable MQTT reporting by checking the «Enable
publishing reports to MQTT» option and entering your broker address
into the appropriate field. You may also have to enter your client ID,
username, and password. By default, OpenWebRX+ reports all its events
under the «openwebrx» topic, but that can be changed by entering
your own topic name into the «MQTT topic» field.

Configuring Map

OpenWebRX+ offers two map options: Google Maps and a
collection of free maps based on the Leaflet library. The
very popular OpenStreetMap is part of that collection.

The Google Maps implementation is more detailed and polished, but
it may require you to register your credit card with Google to receive
an API key. Google may then charge your credit card if you exceed a
certain limit of the Google Maps accesses.

The OpenStreetMap and other maps included with the Leaflet
are less detailed, but they are totally free. Also, the Leaflet
implementation includes some extra layers for weather, maritime
annotations, and so forth.

In order to configure the default map, go to «Settings
| General | Map | Map Type» and select the map you would like to
show to the users by default. Remember that a user can always switch
maps by clicking on the Map button. Other
map-related options available from the same settings section are:

Google Maps API Key
This is where you enter the Google Maps API key you received from
Google. Leave this field empty if you have no API key. A lot of times,
Google Maps will work anyway, for some reason.

OpenWeatherMap API Key
If you would like to see global weather on Leaflet maps, consider
getting an OpenWeatherMap API key and entering it here. These
keys are free, for limited amount of functionality. Without this key,
OpenWebRX+ will only be able to show you US weather, obtained from
WeatherRadar.

Map Retention Time
This is the time, in seconds, the received location reports stay visible
on the map. A location report will start getting dimmer once it becomes
older than half of the retention time. Once it reaches the retention
time, a location report will disappear from the map.

Callsign Database URL
This is the web site used to look up reported HAM callsigns when you
click them on the map. The «{}» characters will be replaced with
the actual callsign. Two common choices here are
qrz.com and
qrzcq.com.

Vessel Database URL
This is the web site used to look up vessel MMSI numbers when you click
them on the map. The «{}» characters will be replaced with the
actual MMSI number.

Flight Database URL
This is the web site used to look up airline flight IDs when you click
them on the map. The «{}» characters will be replaced with the
actual flight ID.

Aircraft Database URL
This is the web site used to look up aircraft Mode-S IDs when you click
them on the map. The «{}» characters will be replaced with the
actual Mode-S ID.

Configuring Shortwave Schedules

Once a day, OpenWebRX+ queries the
EiBi
database for shortwave broadcast schedules. Currently broadcasting
stations are indicated with ⍑ markers on the map and with
bookmarks in the main receiver window.

You can make OpenWebRX+ create bookmarks for currently broadcasting
shortwave stations by setting their maximum range from the receiver
via «Settings | General | Display | Shortwave Bookmarks Range».
OpenWebRX+ will only create bookmarks for shortwave stations located
within that range.

You can also restrict shortwave bookmarks to just a few profiles
(such as 49m / 41m / etc):

Disable global shortwave bookmarks by setting «Settings | General |
Display | Shortwave Bookmarks Range» to zero.

Go to «Settings | SDR Devices and Profiles | <Device> |
<Profile>» and add an option called «Shortwave Bookmarks
Range» by clicking on Add.

Set the newly added option to the maximum range from the receiver
where you would like to see shortwave bookmarks and save profile
settings by clicking on Apply and Save.

It is important to note that the shortwave stations will only show
correctly if you set the correct receiver location in
«Settings | General | Receiver Information | Receiver Location».
It is also important to remember that since OpenWebRX+ queries
EiBi
once a day, the up-to-date information may not be available
immediately after setting the receiver location.

Configuring Repeaters

Once a day, OpenWebRX+ queries
RepeaterBook.com
for the list of repeaters closest to the receiver location. These
repeaters are shown with ⋈ markers on the map and
with bookmarks in the main receiver window.

You can make OpenWebRX+ create repeater bookmarks by setting their
maximum distance from the receiver in «Settings | General | Display |
Repeater Bookmarks Range». OpenWebRX+ will only create bookmarks
for repeaters located within the preset maximum distance.

You can also restrict repeater bookmarks to just a few profiles (such as
VHF / UHF):

Disable global repeater bookmarks by setting «Settings | General |
Display | Repeater Bookmarks Range» to zero.

Go to «Settings | SDR Devices and Profiles | <Device> |
<Profile>» and add an option called «Repeater Bookmarks
Range» by clicking on Add.

Set the newly added option to the maximum distance from the receiver
where you would like to see repeaters and save profile settings by
clicking on Apply and Save.

It is important to note that the repeaters will only show correctly
if you set the correct receiver location in «Settings | General |
Receiver Information | Receiver Location». It is also important to
remember that since OpenWebRX+ queries the
RepeaterBook.com
once a day, the up-to-date repeater information may not be available
immediately after setting the receiver location.

Limiting Receiver Use

As a server administrator, you may have legal or technical
reasons to restrict your OpenWebRX server use by the public.
Always check what radio frequencies and modes you are allowed to listen
to at your location. Do not offer prohibited frequencies and
modes to the public. Following restrictions are available in the
«Settings | General | Receiver Limits»:

Maximum Number of Clients
This setting determines how many people can connect to your OpenWebRX
server at once. Anyone trying to connect to a «full» server will be
shown an error message and refused service.

Maximum Number of Files
This setting determines how many SSTV images, faxes, and other files
received from the air OpenWebRX+ is allowed to keep before it starts
deleting oldest files. The received files can be seen by pressing the
Files button at the top of the receiver web
page.

Session Timeout
This value, in seconds, determines how long a user is allowed to use the
OpenWebRX+ receiver. Reloading receiver’s web page restarts the time
though, so the timeout is mostly there for people who leave their
computers with the OpenWebRX+ page open.

Usage Policy URL
This web page is shown to a user once their session times out. The
default page explains why there is a timeout and lets users find other
online receivers to listen to.

Allow users to chat with each other
Disable this option if you want to disable the built-in chat facility.
When disabled, the chat panel turns into the log panel that does not
accept any input.

Allow users to record received audio
Disable this option if you do not want your users to record any audio
they are listening to. When disabled, the REC
button will disappear from the user interface. Please, do keep in mind
that this does not prevent your users from recording their audio
by some other means.

Allow users to change center frequency
Enable this option if you would like to let your OpenWebRX+ users
«side-step» their current profile by right-clicking the round arrow
buttons. Since this change will occur to all the users listening to the
same profile, it makes sense to disable it on the servers with many
people listening to the same profiles.

Magic Key
When the magic key string is filled in (i.e. not empty), OpenWebRX+ will
only allow side-stepping profiles to people who know the magic key and
provide it as follows:
http://openwebrx.receiver.org:8073/#key=<magic-key>

Monitoring Receiver Use

OpenWebRX+ lets its administrator monitor connections to the
server and ban abusive users. Please, note that since the main
goal of the OpenWebRX project is to provide free, open online radio,
this facility should be used with extreme care. If you want to have a
truly private OpenWebRX server, consider closing it to public access
instead.

In order to see currently connected clients, click on the
Settings button and scroll to the bottom of
the page, until you see the «Clients» display, as shown above.
There, you will be able to ban client’s IP
address for a selected amount of time, or
unban previously banned addresses. A banned
client will still be able to see the map and files, but won’t be able to
access the receiver itself.

You can also broadcast a message to all currently connected
clients by entering it into the input field and clicking the
send button. Your message will show up in
clients’ log / chat panels.

If you are running OpenWebRX+ behind NGINX, you may not be able
to see clients’ IP addresses unless you edit this file:
sudo nano /etc/nginx/sites-enabled/openwebrx
and add the following line to the location section:
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

Advanced MQTT Reporting

As discussed earlier, OpenWebRX can report
received data to an MQTT broker. The
data for each mode is sent under the «openwebrx/<mode>»
topic. For example, FT8 data is reported as «openwebrx/FT8». A
typical report will look as follows:

{
«mode»: «FT8»,
«timestamp»: 1722482895000,
«freq»: 7074985,
«msg»: «CQ YV6BXN FK60»,
«callsign»: «YV6BXN»,
«locator»: «FK60»
}

The common fields present in most reports are:

mode
Mode used to receive the data.
freq
Frequency where the data has been received, in hertz.
timestamp
Reception time, in milliseconds since the Unix epoch.

Reporting Server Startup and Shutdown

In addition to reporting received data, OpenWebRX+ uses MQTT to report
SDR device changes and other internal events. For example, when an
OpenWebRX+ server starts up or shuts down, it sends the following event
under the «openwebrx/RX» topic:

{
«mode»: «RX»,
«timestamp»: 1722737506393,
«version»: «v1.2.64»,
«state»: «ServerStarted»
}

The «state» parameter can be either «ServerStarted» or
«ServerStopped».

Reporting SDR Device Changes

OpenWebRX+ reports SDR device changes under the «openwebrx/RX»
topic that can be used by various automation scripts. Thus, an SDR
profile change will be reported as follows:

{
«mode»: «RX»,
«timestamp»: 1722483751451,
«source_id»: «rspdx»,
«source»: «RSPdx»,
«profile_id»: «air-1»,
«profile»: «Air Band 118-120»,
«freq»: 118900000,
«samplerate»: 2000000
}

The most important fields in the above event are:

source_id
SDR device where profile is being changed. Also see «source» for
a human-readable device name.
profile_id
The new profile. Also see «profile» for a human-readable profile
name.
frequency
The center frequency of the new profile, in hertz.
samplerate
The width of the new profile, in hertz.

When an SDR device starts or stops operating, a state change event is
sent to MQTT:

{
«mode»: «RX»,
«timestamp»: 1722483751451,
«source_id»: «rspdx»,
«source»: «RSPdx»,
«state»: «Running»
}

As seen above, the state change event is very similar to a profile
change, but carries SDR state instead of profile information.

Reporting User Activity

OpenWebRX+ reports user activities under the «openwebrx/CLIENT»
topic. Thus, a user connecting or disconnecting from the server will be
reported as follows:

{
«mode»: «CLIENT»,
«timestamp»: 1722738356255,
«ip»: «::ffff:101.23.45.67»,
«state»: «Connected»,
«banned»: false
}

The «state» parameter can be either «Connected» or
«Disconnected». When a user sends a chat message, that message is
similarly reported under the «openwebrx/CLIENT» topic:

{
«mode»: «CLIENT»,
«timestamp»: 1722738521609,
«ip»: «::ffff:101.23.45.67»,
«name»: «Nickname»,
«message»: «The message text.»,
«state»: «ChatMessage»,
«banned»: false
}

JavaScript Plugins

Stanislav Lechev (LZ2SLL) has developed a
JavaScript plugins framework
for OpenWebRX+. There is a bunch of plugins available from his
GitHub repository.
JavaScript plugins operate in a browser at the client side, rather
than the server side, and allow to customize user interface. In order
to enable JavaScript plugins, rename the following file:

htdocs/plugins/receiver/init.js.sample

into init.js and edit it to enable or disable individual plugins.
The plugins themselves are stored in the following folders:

htdocs/plugins/receiver
Plugins placed into this folder will be loaded into the main receiver
page.

htdocs/plugins/map
Plugins placed into this folder will be loaded into the map view page.

External Transceiver Rig Control

For HAM operators, OpenWebRX+ offers a way to send tuning frequency and
modulation changes to a transceiver rig connected to the OpenWebRX+
server. This is done using
Hamlib
tools, so you will need to install Hamlib prior to enabling rig control
in OpenWebRX+.

Please, keep in mind that unless you are running a private OpenWebRX+
server, letting it control your transceiver is not the best idea,
even though OpenWebRX+ cannot be used to trigger actual radio
transmission.

Once you have installed Hamlib and connected your transceiver to the
OpenWebRX+ server, go to
«Settings | Spotting and Reporting | RigControl Settings»
and select your transceiver model. Then enter the name of a Linux device
your rig is connected to (serial, USB, etc). For network-connected rigs,
enter column-separated IP address and port instead.

If OpenWebRX+ is unable to open your Linux device due to access
restrictions, check what group that device belongs to and add the
«openwebrx» user to the same group:

$ ls -l /dev/ttyUSB0
crw-rw—- 1 root dialout 188, 0 Jan 7 15:28 /dev/ttyUSB0
$ sudo usermod -a -G dialout openwebrx

At this point, you can enable global rig control for all SDR devices and
profiles by checking the «Enable sending changes to a standalone
transceiver» option. Most HAM operators would like to restrict rig
control to certain (shortwave) profiles though. To do that, keep the
global enable option off. Go to a desired profile instead and add
the «Enable sending changes to a standalone transceiver» option
there.

Receiving Satellite Data

To receive satellite weather maps, OpenWebRX+ integrates with the
SatDump
satellite decoder. Unfortunately, since SatDump is not a real-time tool,
the online decoding is not possible. Hence, the users of your receiver
will not be able to make use of SatDump and that is why OpenWebRX+
satellite data support is only available for backup decoding.

If you are running a private OpenWebRX+ server and would like to use it
to receive satellite data, you can manually enable SatDump support and
receive satellite weather images as follows:

Install SatDump by following instructions from the
official GitHub repository.
You can also try installing SatDump from packages available at their
downloads page,
but these may not work on your specific Linux flavor. Source code
compilation is more reliable, although it does take a significant
amount of time.

Enable background decoding for selected satellites by checking
them in «Settings | Background Decoding».

Enable running background services on a chosen SDR device via
«Settings | SDR Devices and Profiles | <Device>», add a
schedule to this device, and create schedule entries for the satellites
you would like to receive and decode.

All received data is stored in the «/tmp/satdump» folder.
For the NOAA decoder, you will see complete images there. For the METEOR
decoder, you will get a .CADU file with data. Use SatDump on your
personal computer to convert this file to actual images.

Frequently Asked Questions

This section attempts to answer some common questions asked by OpenWebRX
users. Please, consult with it before seeking help in online forums or
chat groups.

Everything is broken, help me!
OpenWebRX broken after upgrade!
OpenWebRX features do not show up!
Digital voice modes do not show up!
My SDRplay device does not work reliably!
Can you implement a feature I want?
How do I hide some profiles from users?
How do I jump to any frequency?
How do I enter any frequency?
Where are OpenWebRX configuration files?
How do I make OpenWebRX use HTTPS protocol?
How do I get rid of default yellow bookmarks?
My CPU temperature is wrong!
Band ribbons or green bookmarks are wrong!

Everything is broken, help me!

Before seeking online help from other OpenWebRX users, please, consider
the following steps:

Read other FAQ articles in this document. There is a very good
chance they offer solutions to your problems.

Wait for a day or two, maybe things start working, as they often
do.

If you are not familiar with Linux and do not want or cannot learn,
find a friend familiar with Linux who can offer you hands-on
help.

If you are familiar with Linux, look at OpenWebRX logs by typing
the following command:
sudo journalctl -u openwebrx

If you need even more log output, edit the following file:
sudo nano /etc/openwebrx/openwebrx.conf
and set the log_level in the [core] section:

[core]
log_level = DEBUG

Then save the edited file and restart OpenWebRX.

If you still need help, ask for it in the Telegram channel or create
a separate thread in the forum. Make sure you provide service
logs obtained with the above command, as a file, to whoever
will be willing to help you.

OpenWebRX broken after upgrade!

In a desktop browser, try reloading receiver web page while holding the
SHIFT key. In a mobile browser, clear
browser cache and reload the page. If this does not help, try restarting
the computer running OpenWebRX.

OpenWebRX features do not show up!

Click on «Settings | Feature Report» and see if the features you
are interested in show up as enabled there. If a feature is disabled,
the report will tell you what you should do to enable it.

Digital voice modes do not show up!

Digital voice modes (DMR, D-STAR, YSF, NXDN) require AMBE codec
algorithms patented by Digital Voice Systems Inc. Because of
that, neither OpenWebRX nor OpenWebRX+ include digital voice support out
of the box. It is your personal responsibility to add necessary
pieces to your own OpenWebRX installation.

The proper, legally responsible way to add digital voice modes to
OpenWebRX is to attach a
licensed USB dongle
that implements AMBE codecs in the hardware. Both OpenWebRX and
OpenWebRX+ will support common AMBE dongle models with minimal
configuration effort.

If you do not wish to use an AMBE codec dongle for whatever reason,
there is an unlicensed
MBELib
software implementation with rather questionable origins. The MBELib use
may be interpreted as a patent violation. If you are ok with it, there
is a script that adds MBELib support to
OpenWebRX. Run it as follows:

sudo install-softmbe.sh

After installing digital voice support by either method, visit
«Settings | Feature Report» page to verify that the installation
succeeded. You should now see digital voice buttons at the receiver web
page.

My SDRplay device does not work reliably!

SDRplay devices and their clones are notoriously glitchy and require a
good power source for reliable operation. If you experience timeouts or
failures with these devices, try connecting them via a powered USB hub.
If this does not help, and you have a genuine SDRplay device (not a
clone),
open a ticket
at the SDRplay website. OpenWebRX developers cannot help you
with SDRplay hardware issues.

Can you implement a feature I want?

In general, no. OpenWebRX is a non-profit project, developed by
very few people in their spare time. These developers will prioritize
features they find personally interesting, repeatedly requested by a
lot of people, or easy to implement.

Having said that, there is high probability that the feature you want is
either already implemented, or can be achieved by some other means, or
has been considered and avoided for some reason. Please, carefully read
this document, especially the FAQ section.

Also, since OpenWebRX is an open-source project, nothing prevents you
from adding features you want on your own. Take a look at the
original OpenWebRX source code
or the
OpenWebRX+ source code
and consider participating in the OpenWebRX development.

How do I hide some profiles from users?

Since OpenWebRX is an open online receiver, it does not
let you hide profiles from the public. If you would like to have private
access to your receiver, the best option is to make it inaccessible from
the Internet.

Having said that, there is an option to prevent users from changing
profiles on a specific SDR device connected to OpenWebRX+. It comes
useful if this SDR device performs background decoding and changes
profiles based on its own schedule. To enable this option, do the
following:

Go to «Settings | General Settings | Receiver Limits | Magic Key»
and set the magic key value you would like to use to force
switching profiles on a protected device.

Go to «Settings | SDR Devices and Profiles | <Device>»,
select «Require magic key to switch profiles on this device» from
the «Additional Optional Settings» and click on Add.

Make sure the «Require magic key to switch profiles on this
device» checkbox is checked, then click on Apply and Save.

From now on, users can only change profiles on the device by providing
the preconfigured magic key value in the URL, as follows:

http://openwebrx.receiver.org:8073/#key=<magic-key>

How do I jump to any frequency?

Since OpenWebRX works in terms of «profiles», i.e. preconfigured ranges
of frequencies, you cannot jump to an arbitrary frequency because
that new frequency may require different profile settings. Also, other
users listening to the same profile may not appreciate you jumping to a
completely new frequency.

Nevertheless, OpenWebRX+ does offer a way to «side-step» the current
profile, going to adjacent frequencies. In order to enable
side-stepping, do the following:

Go to «Settings | General Settings | Receiver Limits» and make
sure the «Allow users to change center frequency» checkbox is
checked.

If you would like to protect frequency changes with a magic key, enter
it in the adjacent «Magic Key» field.

Click on Apply and Save to save changes.

From now on, you can step outside the preconfigured frequency range by
right-clicking the large round arrows at the top of the receiver web
page. Mobile users, who do not have a mouse, can simply hold these large
round arrows with their finger for about a second.

If a magic key is configured, you will only be able to side-step
profiles when providing that key in the URL, as follows:

http://openwebrx.receiver.org:8073/#key=<magic-key>

How do I enter any frequency?

Due to the way OpenWebRX operates, you cannot just enter any
frequency into the input field and expect it to work. The entered
frequency must be within the current profile to work. Please,
see above for the reasons.

For a special case where you have allowed
OpenWebRX+ to step outside the preconfigured frequency range, entering
an arbitrary frequency can be enabled with a
JavaScript plugin.

Where are OpenWebRX configuration files?

If you wish to backup OpenWebRX configuration files, they are located as
follows:

/var/lib/openwebrx/settings.json
/var/lib/openwebrx/bookmarks.json
/var/lib/openwebrx/users.json
/etc/openwebrx/openwebrx.conf
/etc/openwebrx/bands.json
/etc/openwebrx/bands-r1.json
/etc/openwebrx/bands-r2.json
/etc/openwebrx/bands-r3.json

You should avoid editing configuration files by hand, since they
are normally modified via web-based settings interface. If you do decide
to edit configuration files, always make sure you have backup
copies first. After updating configuration files, restart OpenWebRX
with:

sudo systemctl restart openwebrx

How do I make OpenWebRX use HTTPS protocol?

While the original OpenWebRX version does not support HTTPS protocol,
OpenWebRX+ does. In order to enable HTTPS in OpenWebRX+, you will
need the SSL certificate file (cert.pem) and the key for it
(key.pem). Once you have these two files, do the following:

sudo cp <cert.pem> /etc/openwebrx/cert.pem
sudo cp <key.pem> /etc/openwebrx/key.pem
sudo chown openwebrx:openwebrx /etc/openwebrx/cert.pem
sudo chown openwebrx:openwebrx /etc/openwebrx/key.pem
sudo chmod 660 /etc/openwebrx/cert.pem
sudo chmod 660 /etc/openwebrx/key.pem
sudo systemctl restart openwebrx

How do I get rid of default yellow bookmarks?

OpenWebRX+ comes with predefined bookmarks for some common frequencies,
such as weather information, CB channels, and so on. If you do not like
to see these bookmarks, delete them and restart OpenWebRX+ as follows:

sudo rm -f /etc/openwebrx/bookmarks.d/*
sudo systemctl restart openwebrx

If you only want to get rid of some bookmarks, delete or edit
individual files in the /etc/openwebrx/bookmarks.d folder.

My CPU temperature is wrong!

By default, OpenWebRX+ tries to determine the correct temperature sensor
automatically. This works 99% of the time, but the remaining 1% may see
their temperatures way outside the realistic range. To tell OpenWebRX+
which sensor to use, edit the following file:

sudo nano /etc/openwebrx/openwebrx.conf

adding the following line to the [core] section:

[core]
temperature_sensor=<full-path-to-your-temperature-sensor>

Then save the edited file and restart OpenWebRX+.

Band ribbons or green bookmarks are wrong!

By default, OpenWebRX+ is configured to use a combined band plan that
mostly applies to all three regions of the ITU world. If you would like
to use a region-specific band plan instead, go to «Settings | General
| Receiver Information | Receiver Band Plan» and select your region
there. If you are still unhappy with the band plan or locations of the
green bookmarks, you can change the default (combined) band plan by
editing the following file:

sudo nano /etc/openwebrx/bands.json

There are also region-specific band plan files in the same folder. Prior
to editing a file, make sure you create a backup copy, in case
something goes wrong. After editing and saving a band plan file, restart
OpenWebRX as follows:

sudo systemctl restart openwebrx

©2023-2025 Marat Fayzullin