Can't get local speaker audio from RTLSDR-Airband

[cvthompson]

dkcorlfla,

Oh man! Thanks again.

When I run "cmake" I get this:

<snip on>
charlievictor102@n701gt:~ $ cd RTLSDR-Airband/
charlievictor102@n701gt:~/RTLSDR-Airband $ cd build
charlievictor102@n701gt:~/RTLSDR-Airband/build $ cmake ../
-- Build type not specified: defaulting to Release
-- Found lame includes: /usr/include/lame/lame.h
-- Found lame library: /usr/lib/aarch64-linux-gnu/libmp3lame.so
-- Checking for module 'libmirisdr'
-- Package 'libmirisdr', required by 'virtual:world', not found
-- Could NOT find MiriSDR (missing: MIRISDR_LIBRARY MIRISDR_INCLUDE_DIR)
-- Checking for SoapySDR
-- Could NOT find SoapySDR (missing: SoapySDR_DIR)
-- SoapySDR not found
-- RTLSDR-Airband configuration summary:

-- - Version string: v5.1.1
-- - Build type: Release
-- - Operating system: Linux
-- - SDR drivers:
-- - librtlsdr: requested: ON, enabled: TRUE
-- - mirisdr: requested: ON, enabled: FALSE
-- - soapysdr: requested: ON, enabled: FALSE
-- - Other options:
-- - Platform: native
-- - Build Unit Tests: FALSE
-- - Broadcom VideoCore GPU: FALSE
-- - NFM support: OFF
-- - PulseAudio: requested: ON, enabled: TRUE
-- - Profiling: requested: OFF, enabled: FALSE
-- - Icecast TLS support: TRUE
-- Configuring done
-- Generating done
-- Build files have been written to: /home/charlievictor102/RTLSDR-Airband/build
<snip off>

I don't think I'm missing "libpulse-dev". I get this:
<snip on>
charlievictor102@n701gt:~/RTLSDR-Airband/build $ cd
charlievictor102@n701gt:~ $ sudo apt install libpulse-dev
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
libpulse-dev is already the newest version (16.1+dfsg1-2+rpt1).
The following packages were automatically installed and are no longer required:
libbasicusageenvironment1 libgroupsock8 liblivemedia77
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
charlievictor102@n701gt:~ $
<snip off>

I ran your "cmake" options and I get this:
<snip on>
charlievictor102@n701gt:~/RTLSDR-Airband $ cd build
charlievictor102@n701gt:~/RTLSDR-Airband/build $ cmake -DPLATFORM=rpiv2 -DMIRISDR=OFF -DSOAPYSDR=OFF -DSOAPYSDR=OFF -DPULSEAUDIO=ON -DNFM=ON ../
-- Build type not specified: defaulting to Release
-- Found lame includes: /usr/include/lame/lame.h
-- Found lame library: /usr/lib/aarch64-linux-gnu/libmp3lame.so
-- The ASM compiler identification is GNU
-- Found assembler: /usr/bin/c++
-- Could NOT find BCM_VC (missing: BCM_VC_LIBRARY BCM_VC_INCLUDE_DIR)
-- RTLSDR-Airband configuration summary:

-- - Version string: v5.1.1
-- - Build type: Release
-- - Operating system: Linux
-- - SDR drivers:
-- - librtlsdr: requested: ON, enabled: TRUE
-- - mirisdr: requested: OFF, enabled: FALSE
-- - soapysdr: requested: OFF, enabled: FALSE
-- - Other options:
-- - Platform: rpiv2
-- - Build Unit Tests: FALSE
-- - Broadcom VideoCore GPU: FALSE
-- - NFM support: ON
-- - PulseAudio: requested: ON, enabled: TRUE
-- - Profiling: requested: OFF, enabled: FALSE
-- - Icecast TLS support: TRUE
-- Configuring done
-- Generating done
-- Build files have been written to: /home/charlievictor102/RTLSDR-Airband/build
<snip off>

Does this mean I'm missing "BCM_VC"? In case it is not clear, I am a complete NOOB when it comes to Linux and Raspberry Pi.

Curtis

 

[cvthompson]

dkcorlfla,

This is probably better options for my setup.
<snip on>
charlievictor102@n701gt:~/RTLSDR-Airband/build $ cmake -DPLATFORM=native -DMIRISDR=OFF -DSOAPYSDR=OFF -DSOAPYSDR=OFF -DPULSEAUDIO=ON ../
-- Build type not specified: defaulting to Release
-- Found lame includes: /usr/include/lame/lame.h
-- Found lame library: /usr/lib/aarch64-linux-gnu/libmp3lame.so
-- RTLSDR-Airband configuration summary:

-- - Version string: v5.1.1
-- - Build type: Release
-- - Operating system: Linux
-- - SDR drivers:
-- - librtlsdr: requested: ON, enabled: TRUE
-- - mirisdr: requested: OFF, enabled: FALSE
-- - soapysdr: requested: OFF, enabled: FALSE
-- - Other options:
-- - Platform: native
-- - Build Unit Tests: FALSE
-- - Broadcom VideoCore GPU: FALSE
-- - NFM support: ON
-- - PulseAudio: requested: ON, enabled: TRUE
-- - Profiling: requested: OFF, enabled: FALSE
-- - Icecast TLS support: TRUE
-- Configuring done
-- Generating done
-- Build files have been written to: /home/charlievictor102/RTLSDR-Airband/build
charlievictor102@n701gt:~/RTLSDR-Airband/build $
<snip off>

Curtis

 

[dkcorlfla]

dkcorlfla,

This is probably better options for my setup.
<snip on>
charlievictor102@n701gt:~/RTLSDR-Airband/build $ cmake -DPLATFORM=native -DMIRISDR=OFF -DSOAPYSDR=OFF -DSOAPYSDR=OFF -DPULSEAUDIO=ON ../
-- Build type not specified: defaulting to Release
-- Found lame includes: /usr/include/lame/lame.h
-- Found lame library: /usr/lib/aarch64-linux-gnu/libmp3lame.so
-- RTLSDR-Airband configuration summary:

-- - Version string: v5.1.1
-- - Build type: Release
-- - Operating system: Linux
-- - SDR drivers:
-- - librtlsdr: requested: ON, enabled: TRUE
-- - mirisdr: requested: OFF, enabled: FALSE
-- - soapysdr: requested: OFF, enabled: FALSE
-- - Other options:
-- - Platform: native
-- - Build Unit Tests: FALSE
-- - Broadcom VideoCore GPU: FALSE
-- - NFM support: ON
-- - PulseAudio: requested: ON, enabled: TRUE
-- - Profiling: requested: OFF, enabled: FALSE
-- - Icecast TLS support: TRUE
-- Configuring done
-- Generating done
-- Build files have been written to: /home/charlievictor102/RTLSDR-Airband/build
charlievictor102@n701gt:~/RTLSDR-Airband/build $
<snip off>

Curtis

I think with those options you should be able to run either server, pulseaudio or ice cast. There was a duplicate on the soapysdr off option I missed but it did seem to cause any issues. The bcm warning I think has to do with the built in sound chip so if you are going to use a USB card it might not matter. I have the full log of when I compiled it so if it does not compile let me know and I can try and compare. A couple of notes, I'm running the 32 bit lite os version so there maybe a few differences but I think you are very close to getting it working. I have been running the program over the weekend and I very impressed. Try to get the pulseaudio server going. For local playback it is excellent. I like the program so much I'm going to try and compile it on a Raspberry zero 2. Can the tiny zero run it? Should be interesting.

 

[cvthompson]

dkcorlfla,

I did not think Icecast was working. But after 1 minute and 20 seconds my voice from a handheld came through. Not really optimal for my use case (Airband radio in the hangar).

I just heard a radio call from an aircraft directly over my house. I'm about 15 miles south of the airport (non towered) where I have my experimental aircraft.

I think the BCM warning was because I was compiling it for the RPi 4 and not the RPi 3 like you. I change the "cmake" options. I didn't get any errors when I did "make".

I'll look more into PulseAudio tomorrow. Any idea what commands I can issue to see if PulseAudio is working?

Curtis

 

[cvthompson]

Here is what I get from "pactl":

charlievictor102@n701gt:~ $ pactl info
Server String: /run/user/1000/pulse/native
Library Protocol Version: 35
Server Protocol Version: 35
Is Local: yes
Client Index: 111
Tile Size: 65472
User Name: charlievictor102
Host Name: n701gt
Server Name: PulseAudio (on PipeWire 1.2.7)
Server Version: 15.0.0
Default Sample Specification: float32le 2ch 48000Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.usb-1130_USB_AUDIO-00.analog-stereo
Default Source: alsa_output.usb-1130_USB_AUDIO-00.analog-stereo.monitor
Cookie: 87ae:eb10
charlievictor102@n701gt:~ $

Curtis

 

[dkcorlfla]

dkcorlfla,

I did not think Icecast was working. But after 1 minute and 20 seconds my voice from a handheld came through. Not really optimal for my use case (Airband radio in the hangar).

I just heard a radio call from an aircraft directly over my house. I'm about 15 miles south of the airport (non towered) where I have my experimental aircraft.

I think the BCM warning was because I was compiling it for the RPi 4 and not the RPi 3 like you. I change the "cmake" options. I didn't get any errors when I did "make".

I'll look more into PulseAudio tomorrow. Any idea what commands I can issue to see if PulseAudio is working?

Curtis

 

[dkcorlfla]

With such a long delay you must have the icecast server set to use a remote system over the WAN side of the network. icecast from a quick read can be setup to run local and that may be a good option for you too but I went with the pluseaudio running local on the same pi as the RTLSDR-Airband. I do not have any aircraft TX available to test but I think the delay is only a few mil seconds.

Here is the output of the running Pi 3B+

bogus@mainframe:~ $ pactl info
Server String: /run/user/1002/pulse/native
Library Protocol Version: 35
Server Protocol Version: 35
Is Local: yes
Client Index: 3
Tile Size: 65496
User Name: bogus
Host Name: mainframe
Server Name: pulseaudio
Server Version: 16.1
Default Sample Specification: s16le 2ch 44100Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.usb-0d8c_C-Media_USB_Headphone_Set-00.analog-stereo
Default Source: alsa_input.hw_0
Cookie: ce9e:5fbb
bogus@mainframe:~ $
---------------------------------

Don't know why yours shows on (pipewire)
Here is the output of my: pacmd

bogus@mainframe:~ $ !369
pacmd list-modules|grep protocol-tcp

name: <module-native-protocol-tcp>
bogus@mainframe:~ $

Please not the use of the !369 to rerun a previous command, don't use this number but to get a feel for how history works open a terminal window and enter

uptime

then history, and note the number for the last command - uptime

To rerun simply type !number

You will see the time is a bit later on the rerun.

Tremendously powerful command and I use it all the time to rerun or get the syntax of a complex command that I can't quite fully remember. It can also be used to review what you did previously.

The command history > history1.txt will send the output to a file in whatever directory you are in. If you get stuck I may be able to review and try to figure out why it's not working.

Make sure to review the post above about the: pacmd list-modules|grep protocol-tcp

What you want to see is: name: <module-native-protocol-tcp>

To get it working add: load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1 to the config file:
sudo nano /etc/pulse/default.pa

 

[dkcorlfla]

I forgot to mention htop will show if pulseaudio is running along with everything else. q to quit

I'm going to be trying to get it all working on a pi zero2 so I might have even more trouble shooting ideas depending on what I can get to work or not.

 

[cvthompson]

When I run "pacmd list-modules" I get this:

charlievictor102@n701gt:~ $ pacmd list-modules
No PulseAudio daemon running, or not running as session daemon.
charlievictor102@n701gt:~ $

I added "load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1" to the "/etc/pulse/default.pa" config file.

I then rebooted RPi 4.

I get the same result from the "pacmd" command as above (No PulseAudio daemon running, or not running as session daemon).

I then run the "htop" command and filter for "pulse". I get three entries tat show "/user/bin/pipeware-pulse". Nothing about PulseAudio.

When I start rtl_airband with the -e option so it sends errors to stderr, I get these errors periodically:

pulse: <default_server>: connecting...
pulse: <default_server>: connection failed: Connection refused
pulse: <default_server>: failed to connect: Invalid argument

I could not figure out how to get to the rtl_airband log files like from the wiki but I figured that using the -e option would be the same thing.

Any help would be welcome.

Curtis

 

[cvthompson]

dkcorlfla,

The reason I was getting the "connection failed: Connection refused" error was that I was missing the "server = "127.0.0.1";" from the rtl_airband.conf file.

Also, I don't think PulseAudio is started automatically. I used "pulseaudio --start".

When I run "sudo /usr/local/bin/rtl_airband -f -e" I now get:

pulse: 127.0.0.1: connecting...
pulse: 127.0.0.1: stream "Utility channels" connected

But still no audio from the USB or 3.5mm jack when the radio un-squelches.

In regards to something you wrote earlier about icecast, I think I have it set up to connect locally. I don't think it is going off the RPi. Doesn't explain the 1.4 minute transit delay.

With your PulseAudio setup, does the audio come out shortly after the "*" on the waterfall? That would tell me there is only a short delay.

I ordered a RPi 3+ so I can try it with that.

Curtis

 

[dkcorlfla]

dkcorlfla,

The reason I was getting the "connection failed: Connection refused" error was that I was missing the "server = "127.0.0.1";" from the rtl_airband.conf file.

Also, I don't think PulseAudio is started automatically. I used "pulseaudio --start".

When I run "sudo /usr/local/bin/rtl_airband -f -e" I now get:

pulse: 127.0.0.1: connecting...
pulse: 127.0.0.1: stream "Utility channels" connected

But still no audio from the USB or 3.5mm jack when the radio un-squelches.

In regards to something you wrote earlier about icecast, I think I have it set up to connect locally. I don't think it is going off the RPi. Doesn't explain the 1.4 minute transit delay.

With your PulseAudio setup, does the audio come out shortly after the "*" on the waterfall? That would tell me there is only a short delay.

I ordered a RPi 3+ so I can try it with that.

Curtis

I did double check the delay on the Pi by running gqrx on my very strong desktop and had it monitoring MCO final (very busy) while I also had the Pi scanning. The audio was not always the same as I had the Pi scanning and the desktop just on one frequency but when they both were on the same channel I could not detect any delay on the Pi vs the desktop. There might be a slight delay caused by the processing of the signal but it is less then 1/4 second I'm sure. I have used the gqrx program on ham radio that's why I'm sure there is no delay.

Looks like you are very close to getting it working.

I will try to look into the pulseaudio not running.

You did enable and start it?

bogus@mainframe:~ $ !362
systemctl --user status pulseaudio
● pulseaudio.service - Sound Service
Loaded: loaded (/usr/lib/systemd/user/pulseaudio.service; enabled; preset: enabled)
Active: active (running) since Mon 2025-07-14 08:34:19 EDT; 5h 56min ago
--
systemctl --user enable pulseaudio
systemctl --user start pulseaudio

The enable command might need to be run as root not sure
sudo systemctl enable pulseaudio

Hope this helps

 

[dkcorlfla]

Just got the Raspberry Pi zero 2 running and have the full install log of all the steps let me know if you would like to see it. I can post it here or PM?

 

[cvthompson]

Yes @dkcorlfla. Can you please PM that install log to me?

I decided to start over with a RPi 3B+ that I just got from Amazon.

I'm at the point where I just loaded the 32-bit OS on that RPi 3B+.

Curtis

 

[dkcorlfla]

Yes @dkcorlfla. Can you please PM that install log to me?

I decided to start over with a RPi 3B+ that I just got from Amazon.

I'm at the point where I just loaded the 32-bit OS on that RPi 3B+.

Curtis

PM sent, it was a real big help to me having the working Pi 3B+ to go back and review the complex commands.

The Pi zero 2 went without a hitch, got it going on the first go with the help from the 3B+

The zero2 is working great - only got ya was the wifi setup - turns out the zero2 does not support current routers if you are using WPA3.

That's why there is a wifi dongle plugged into the USB hub adapter.

I would not recommend the zero 2 for this reason but it is working fine and if you run WPA2 it would not be an issue.

 

[cvthompson]

This has happened before with the RPi 4 but after building the RTLSDR Blog V4 software on the RPi 3B+ and doing a reboot, it only comes up in a console without a desktop. It says it can't find "raspi-config". I'm going now to Walmart to get another SD Card and starting over.

I'll look for the PM.

Thanks again.

Curtis

 

[cvthompson]

PM sent, it was a real big help to me having the working Pi 3B+ to go back and review the complex commands.

The Pi zero 2 went without a hitch, got it going on the first go with the help from the 3B+

The zero2 is working great - only got ya was the wifi setup - turns out the zero2 does not support current routers if you are using WPA3.

That's why there is a wifi dongle plugged into the USB hub adapter.

I would not recommend the zero 2 for this reason but it is working fine and if you run WPA2 it would not be an issue.

Eureka!

I have it working on my RPi 3B+ with USB speakers.

I'm listening to approach frequencies near Seattle. I can hear my home airport from about 20 miles away too. No throughput delay. I'll need to adjust the gain and squelch, but this should work for an airband receiver in my hangar at the airport.

Use of my airband handheld did not work as expected. Handheld signal is so strong it saturates the receiver and all I hear is static with it.

I made a few changes to the guidance you sent in the DM. Of course, I had to build the special version of the RTLSDR driver for my dongle. I did not muck with the audio channel re-assignment in the "alsa-base.conf" file. It came out the USB speaker without having to do that. I did not enable "-DNFM=ON".

I'm not sure what my problem was on the RPi 4.

I might start over with the RPi 4. I want to stream my local flightaware webpage with the map display.

Thank you so much for helping me with this. I think I would have given up without your help.

Curtis

 

[dkcorlfla]

Eureka!

I have it working on my RPi 3B+ with USB speakers.

I'm listening to approach frequencies near Seattle. I can hear my home airport from about 20 miles away too. No throughput delay. I'll need to adjust the gain and squelch, but this should work for an airband receiver in my hangar at the airport.

Use of my airband handheld did not work as expected. Handheld signal is so strong it saturates the receiver and all I hear is static with it.

I made a few changes to the guidance you sent in the DM. Of course, I had to build the special version of the RTLSDR driver for my dongle. I did not muck with the audio channel re-assignment in the "alsa-base.conf" file. It came out the USB speaker without having to do that. I did not enable "-DNFM=ON".

I'm not sure what my problem was on the RPi 4.

I might start over with the RPi 4. I want to stream my local flightaware webpage with the map display.

Thank you so much for helping me with this. I think I would have given up without your help.

Curtis

First congrats on not giving up and sticking to it. Second I would like to thank you for putting me on to this amazing software. I got a lot out of figuring it out and I'm happy to help.

The build option "-DNFM=ON" is for scanning and receiving NFM. Not needed if you are only interested in airband AM.

I have it scanning the VHF and UHF NFM ham bands now on the Pi 3B+ and it's working perfect.

Here are some thoughts that might be of interest. If the Pi is going to be left at the airport hanger and you live 20 miles away then streaming to a pulseaudio or icecast server at home might be something to consider. You could monitor ground traffic and the tower from you house for example. Maybe ATIS too but I don't know how to lockout a channel yet.

The Pi 4 would have enough horse power to run Flightaware and SDRRTL-Airband at the same time but you would need to install Flightaware onto a full Raspberry OS instead of using the pre-made Flightaware image as it would be missing a lot of the needed dependencies.

Enjoy

 

[cvthompson]

First congrats on not giving up and sticking to it. Second I would like to thank you for putting me on to this amazing software. I got a lot out of figuring it out and I'm happy to help.

The build option "-DNFM=ON" is for scanning and receiving NFM. Not needed if you are only interested in airband AM.

I have it scanning the VHF and UHF NFM ham bands now on the Pi 3B+ and it's working perfect.

Here are some thoughts that might be of interest. If the Pi is going to be left at the airport hanger and you live 20 miles away then streaming to a pulseaudio or icecast server at home might be something to consider. You could monitor ground traffic and the tower from you house for example. Maybe ATIS too but I don't know how to lockout a channel yet.

The Pi 4 would have enough horse power to run Flightaware and SDRRTL-Airband at the same time but you would need to install Flightaware onto a full Raspberry OS instead of using the pre-made Flightaware image as it would be missing a lot of the needed dependencies.

Enjoy

I was thinking that you might be tuning in some other bands and thus "-DNFM=ON".

I have had FlightAware (piaware) running at the hangar on a different RPi 4 for about a month. Scanning ADS-B on 1090ES and UAT978. I'm serving it up to FlightAware. I am trying to solve a problem were the tracks of close in aircraft drop out periodically. I thought I was overdriving the receiver but I played a lot with the gain setting and in-line attenuators. There is a lot of information on the local piaware website that is not served up remotely. Like "RSSi" and time since last reception. When there is a gap in the flight track, I see that there are still incoming ADS-B messages. I'm still trying to figure that out.

That piaware web page is what I want to display in the hangar. This will be on a second RPi 4 which is also running the RTLSDR-Airband. Two RPi mostly because it simplifies antenna location and wiring. But I have enough Raspberry Pi's now that I could have piaware on one RPi 4, map on the second RPi 4, and the Airband RX on the RPi 3.

I tried to get RTLSDR-Airband to work on the RPi 4 since I last wrote. Once using the 64-bit version of the full OS and the other on the 32-bit full version. Both get stuck with the "Active: inactive (dead)" PulseAudio issue. Everything else with rtl_airband seems to work.

I have occasionally been listening to the CTAF frequency at my home network via LiveATC. I don't care about the 1.4 minute delay via the web when I'm at home. The "Cherokee Owners Association" is evidently serving that up. I don't think it makes sense for me to serve it up too.

Thanks again,

Curtis

 

[dkcorlfla]

I was thinking that you might be tuning in some other bands and thus "-DNFM=ON".

I have had FlightAware (piaware) running at the hangar on a different RPi 4 for about a month. Scanning ADS-B on 1090ES and UAT978. I'm serving it up to FlightAware. I am trying to solve a problem were the tracks of close in aircraft drop out periodically. I thought I was overdriving the receiver but I played a lot with the gain setting and in-line attenuators. There is a lot of information on the local piaware website that is not served up remotely. Like "RSSi" and time since last reception. When there is a gap in the flight track, I see that there are still incoming ADS-B messages. I'm still trying to figure that out.

That piaware web page is what I want to display in the hangar. This will be on a second RPi 4 which is also running the RTLSDR-Airband. Two RPi mostly because it simplifies antenna location and wiring. But I have enough Raspberry Pi's now that I could have piaware on one RPi 4, map on the second RPi 4, and the Airband RX on the RPi 3.

I tried to get RTLSDR-Airband to work on the RPi 4 since I last wrote. Once using the 64-bit version of the full OS and the other on the 32-bit full version. Both get stuck with the "Active: inactive (dead)" PulseAudio issue. Everything else with rtl_airband seems to work.

I have occasionally been listening to the CTAF frequency at my home network via LiveATC. I don't care about the 1.4 minute delay via the web when I'm at home. The "Cherokee Owners Association" is evidently serving that up. I don't think it makes sense for me to serve it up too.

Thanks again,

Curtis

I have run Flightaware before, my house is directly under the ILS to 18R at MCO. Something is not right as I never had any skips other then when the aircraft was just about to land, very low and about 7 miles away. What type of antenna and what range do you see out to? I was using one of the 1090 Mhz dedicated on my setup and it was solid out to 150 miles.

Regarding pulseaudio , sudo systemctl enable pulseaudio should start it at boot. sudo systemctl start should get it running during session and status to verify.

 

[cvthompson]

It seems that PulseAudio is not running at startup. Even if I execute "systemctl --user enable pulseaudio" and reboot.

I always have to run "pulseaudio --start" and then run "rtl_airband".

Is there a way that I can run these two commands automajically at startup without a shell login?
pulseaudio --start
/usr/local/bin/rtl_airband

Curtis

p.s. I'm using two of these antennas (Amazon.com: Acxico 1Pcs ADS-B 1090MHZ PCB Antenna ANT : Electronics). I added about 10mm to one to get it to work on 978MHz. Checked with a NanoVNA. I can get 1090MHz ADS-B out to at least 150 miles with AGC enabled. But then local traffic overdrives the receiver. I turned off the AGC and manually set the gain to get close in traffic.