[arm-allstar] adding a sdr to allstar node

[David McGough]

Hi Joe,

Ultimately, it should be very easy to interface an RTL-SDR with
the new chan_iopipe HamVoIP/AllStar channel driver. This code is still in 
alpha test right now, but is the next project for completion in the 
pipeline.

Quickly thinking about this, I can see at least a couple caveats to 
overcome:

....You'll need some strategy to generate COS telemetry from the
RTL-SDR audio/data stream or this solution will have serious limitations 
for any kind of general purpose AllStar use. iopipe has a high-performance
DSP squelch module in development. That might be applicable.

....There is a pretty substantial time delay going through the entire 
rtl-sdr signal chain---from the hardware dongle through the RTL DSP 
software. This may be tedious for general purpose / every day use??

I expect an RTL-SDR RX would probably fit more into the category of 
auxiliary RX; such as a frequency agile receiver of HF receiver, etc. 
Something where you're not trying to carry on a 2-way conversation.

I agree though that the little RTL-SDR's are pretty cool hardware. I've 
also got an AirSPY SDR dongle. Very impressive! Unfortunately, taking 
full advantage of the AirSPY requires more CPU horsepower than the RPi3 
can muster, unless perhaps the GPU could be harnessed to do some of the 
heavy DSP lifting???

73, David KB4FXC



On Wed, 23 May 2018, "KD2NFC - Joe via arm-allstar" wrote:

> Ive been on a quest to use a rtlsdr dongle as radio receive with my Baofeng
> for transmit. Not sure if its possible yet but I was able to add my rtlsdr
> dongle to ASL and call it up on the node or direct dial it from a sip or iax
> end point. 
> 
>  
> 
> Here are instructions:
> 
>  
> 
> Install the rtl-sdr drivers on the node. I'm using the Arch Linux OS so I do
> 
>  
> 
> Pacman -S rtl-sdr 
> 
>  
> 
> I compiled the keenerds version as he have some bells and whistles in his
> build but you just install the package.  
> 
>  
> 
> Add these commands to rc.local, they will setup the loopback and get rtl_sdr
> piping audio to the loopback.  Check the frequency (-f ) to whatever you
> like, you can 146125000 syntax as well. 
> 
>  
> 
> modprobe snd-aloop   ; <-put this before asterisk loading
> 
>  
> 
> rtl_fm  -M fm -f 145640000  -s 30000 -r 12k -g 3.0 | aplay -r 12k -D
> default:CARD=Loopback -c 1 -f S16_LE &  ; <-put this after asterisk loads
> 
>  
> 
>  
> 
> create a alsa.conf in /etc/asterisk/
> 
>  
> 
> add this.
> 
>  
> 
> [general]
> 
> autoanswer=yes
> 
> context=local
> 
> extensions=s
> 
> language=de
> 
> input_device=hw:1,1,0
> 
> output_device=hw:1,0,1  
> 
>  
> 
>  
> 
> I'm using usbaudio and it works with Simpleusb also but you have to enable
> chan_alsa.so in modules.conf
> 
>  
> 
> Next create a file called console.conf in the /etc/asterisk directory
> 
>  
> 
> Add this..
> 
>  
> 
> [default]
> 
> input_device = default
> 
> output_device = default
> 
> autoanswer = yes
> 
> context = default
> 
> extension = s
> 
> callerid = Radio Console KD2NFC <(0049) 123456789>
> 
> language = en
> 
> overridecontext = no
> 
> mohinterpret = default
> 
> active = yes
> 
>  
> 
>  
> 
> I can connect with my sip device by adding this to my extentions.conf 
> 
>  
> 
> [dialplan]
> 
> exten => 222,1,Authenticate(1234)    ; use password 1234 to connect or
> comment out this and the playback line below, you have to renumber the
> order. 
> 
> exten => 222,2,Playback(access-granted)
> 
> exten => 222,3,Dial(Console/default)
> 
> exten => 222,n,Hangup()
> 
>  
> 
>  
> 
> If you add it to a dialplan context setup to work with your node you can get
> to it by doing a autopatch. Rpt fun <yournode#> *6222
> 
> Or dial 222 with your sip or iax endpoint. Make sure their contexts points
> to the dial plan with the extension you added. 
> 
>  
> 
> Reboot, don't forget to plug the rtl-sdr dongle in. 
> 
>  
> 
> This could be good to get a signal into the node like noaa weather, or maybe
> you just want to monitor another RF repeater local to you on the node. For
> now I have it listening to the frequency I have a svxlink node on and that
> has some cool propagation alerts I setup and when they fire I can hear it
> when I'm all my all star link node. 
> 
>  
> 
> Cheers.
> 
>  
> 
>  
> 
>  
> 
> Joe
> 
> Kd2nfc
> 
>  
> 
>  
> 
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> 
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> 
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