Yellow VHF Stick no audio

[[email protected]]

Been trying to set up a yellow stick, but with no joy.  The Pi can see the stick, and I changed it's serial number, so it is there.

It doesn't have an led, like the green ones. Is this normal?

Went through the setup instructions for the pi, and these bombed in several places.

* The version of the OS is bullseye, which isn't recognised, so I had to add an entry pointing to the buster repo. 
* The GPG key for the repo tries to go to a non-existent URL, so I had to edit this, and point it to the ubuntu key repo.
* apt-key is deprecated, though still works for now.
* The buster version of rtl-airband-rb exits with failed to start SDR AM/NFM demodulator

Ended up building rtl-airband from the git repo, and it runs and I'm online. No audio though.

I have an airband scanner, and it works fine with the antenna. I get almost continuous output, so it isn't the antenna.

Tried the stick with SDR++ and CubicSDR on my mac, just to see if I can get audio, but nothing. They see the stick too, just no audio

[abcd567]

Try this:

https://github.com/charlie-foxtrot/RTLSDR-Airband

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[[email protected]]

Thanks. Will give that one a go.

[[email protected]]

Thanks, that was the solution. Getting audio now.  icecasting it locally to test. 

[abcd567]

Great. Congratulations.

The site "https://github.com/charlie-foxtrot/RTLSDR-Airband" completely lacks instructions as to "how to build & install". I am posting below all steps for anyone else who wants to build and install rtl_airband from this site.

Last night I build and install it on RPi Model 4 with 64-bit RaspberryPi OS Bookworm
I had to do following:

STEP-1: Installed packages needed to build

Code: [Select]

sudo apt install cmake make gcc g++ gdb pkg-config

sudo apt install build-essential autoconf automake libtool

sudo apt install libusb-1.0-0-dev librtlsdr-dev libsoapysdr-dev

sudo apt install lame libmp3lame-dev libshout-dev cl-fftw3 libpulse-dev


Build and installed package "libconfig" from source code

Code: [Select]

wget https://hyperrealm.github.io/libconfig/dist/libconfig-1.7.3.tar.gz
sudo tar -xvpf libconfig-1.7.3.tar.gz
cd libconfig-1.7.3
./configure
make
make install
sudo cp libconfig++.pc  libconfig.pc /usr/bin/


STEP-2: Build & installed binary "rtl_airband" from source-code:

Code: [Select]

git clone https://github.com/charlie-foxtrot/RTLSDR-Airband.git

cd RTLSDR-Airband

sudo mkdir build

cd build 

sudo cmake ../

sudo make

sudo make install



Started service rtl_airband

Code: [Select]

sudo service rtl_airband restart

sudo service rtl_airband status


[[email protected]]

The github site had a wiki link with full build instructions.  Wasn't hard. The radarbox version needs some attention.

Not very impressed with the receiver though. Not picking up much, and quite a lot of static noise on more distance calls. I'm using an external J Pole antenna, and have tested that same antenna with my old UBC93XLT scanner. The Uniden picks up lots of traffic, and is very clear, with very little static on distant calls.  Only close traffic is clear on the yellow stick.

I have set squelch to -42, which is little above the background noise  stops triggering too often. Pretty much what I do with the Uniden scanner.

I'm going to try using a few SDR software packages to see if it is a software decoding/filtering issue, rather than the receiver. 

[[email protected]]

SDR++ works nicely, though has some quirks. I can't get the scanner module to output audio, though it does scan. I also can't get the multiple radio option to work. Single channel works fine.

Sound wise, SDR++ is similar to my handheld scanner.  Having the FFT display is good too. It looks like the Yellow stick is slightly off frequency (~2kHz too high). 

Tried CubicSDR too, but there is a lot of background noise with signals. It has an FFT display too, and it also shows that the yellow stick is slightly off frequency.

Also found my old 1970's handheld transistor airband radio, with manual tuning. It is actually the best of them all.  Very sensitive radio, and very clear signal using just a short whip antenna.

[abcd567]

Also found my old 1970's handheld transistor airband radio, with manual tuning. It is actually the best of them all.  Very sensitive radio, and very clear signal using just a short whip antenna.

Since last 15 years, I am using Grundig Satellit 750 receiver (not a scanner) to listen to Airband. No outdoor antenna, only the built-in telescopic antenna of the receiver

Prior to purchasing it, for over two decades, I used a low cost old fashioned portable AM/FM receiver with manual tuning by variable gang capacitor, whose FM tuner I had modified to receive Air Band.

I took advantage of image frequency. When needle was set at 100 Mhz on the dial, the oscillator frequency was 100+IF= 100+10.7=110.7 mhz. This oscillator frequency not only hetrodyned with 100 mhz to produce IF (10.7 mhz), but also hetrodyned with 121.4 mhz to produce 10.7 mhz IF (121.4 - 110.7 = 10.7). Thus at dial reading of 100mhz (fm band), it could receive 121.4 mhz also (air band). However antenna coil+gang capacitor were designed to tune at 100 mhz when oscillator was at 110.4, so 121.4 was rejected. I simply changed antenna coil with lower inductance to tune antenna circuit at 121.4 mhz when dial was indicating 100 mhz and oscillator was at 110.7 mhz.

To summerize, the only thing I did to convert FM band to Air band was to replace antenna circuit coil with another coil of lesser number of turns (lesser inductance).

Now the antenna circuit, which was tuning to (oscillator frequency - IF), started tuning to (oscillator frequency + IF)

In additiin to modifying the FM tuner, I had to slightly detune it to get AM demodulation from FM demodulator by operating it at slope of FM demodulator curve. Slight detuning was easy as I did not use a radio with digital (PLL) tuner. It was old fashioned analog receiver with variable gang capacitor, knob, needle & dial. Please see attached sketch.

[abcd567]

SDR++ For Linux / Debian

https://salsa.debian.org/debian-hamradio-team/sdrpp#linux


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[[email protected]]

The hope was to put the antenna well away from my man cave. The reception here is horrible compared to moving 40m down the hill.  The idea is to put a cheap airband receiver down the hill, and feed it here. That would keep my portable scanner free.

Here, I get just the aircraft end. Further down the hill, I get the tower end too.   I assume this is the terrain between here and the airport.  There is no line of sight from either location (400m range of hills in the way). The signal must be bouncing of the hills to get here.

[abcd567]

@rob

What is the final outcome of your efforts?
Could you achieve your objective?

[[email protected]]

Still playing. Digitising my scanner would give me the best results, and/or the old transistor radio. The latter would be single channel, as it is manually tuned (and I would need to adapt it for an external antenna).  Or doing it the old fashion way, and just running an audio cable.

With the Yellow stick, SDR++ is the best option so far. There might be others that work well too.  The scanner module isn't the best with SDR++, but the single channel is ok. Can't get the multi-radio option to work as advertised either, but the software is being actively update, so these might improve.

I want to be listening on at least 3 frequencies. Auckland Control, Auckland Approach, and Auckland Approach 2.  The Auckland Tower is hard for me to hear, but I get both ends on the others.

[abcd567]

Great!
Thanks for update.
Keep us updated as you progress.