[Xastir] Off-topic: Rx eight freq. at once via RTL SDR: Send to Icecast

[Curt Mills]

I started with "rtl_fm", piping to "lame" and then to "ezstream". That gave
me one audio channel to send to the Icecast server. "rtl_fm" has another
mode where you can give it multiple frequencies and it scans between them,
still only one audio channel.  http://kmkeen.com/rtl-demod-guide/

Correction from previous message: Now that I look at the sources, it looks
like it was "rtl_fm.c" in the "rtl-sdr" package that had to be patched for
the zero-samples-on-squelch rather than the method I'm using now. The patch
allows the audio stream to continue when the "radio" gets squelched.
Without it the stream keeps stopping and have to connect again with your
audio client, which is untenable.

What I'm doing now: Running RTLSDR-Airband against one RTL SDR, decoding 8
different FM frequencies all at once (or 8 AM frequencies, such as
aircraft), creating 8 audio streams, and sending all 8 streams to Icecast
concurrently. So you can have multiple users connected to Icecast listening
to whichever frequencies they like. You should be able to do ALL of this
including some limited number of users connected to Icecast with an Rpi 3.
I hear only one frequency corresponding to the audio stream URL I select
from the audio client on my phone/tablet/laptop, but other users can be
listening to any of the channels at the same time, up to however many users
Icecast and your server can handle. If you use an external service instead
of Icecast locally and feed the 8 streams to that service, you can have an
unlimited number of people listening at once.


On Thu, Jan 19, 2017 at 10:04 AM, Dana Rawding <dana at twc-inc.net> wrote:

> I’m interested to hear more!  I’ve been doing something similar using gqrx
> and a RTL-SDR receiver to scan the frequencies I’m interested in.  I pipe
> it out to vlc with the following:
> cvlc --demux=rawaud --rawaud-channels=1 --rawaud-samplerate=48000
> udp://@:7355 --sout '#standard{access=http,mux=ogg,dst=192.168.X.X:8888}’
>
> It sounds like you have a much more elegant solution.  If two frequencies
> are active at once do you hear both?  The way I do it works like a
> traditional scanner but I think your method is more like an ACARS scanner
> which listens to multiple frequencies at once.  I’m also interested in how
> you are able to do 8 freqs as the best I’ve been able to do is 4.  Are your
> frequencies are relatively close together?  For instance using this method
> I’m able to listen to multiple freqs from 130 to 132 but I can’t pick up
> the channels in 136 because the sdr doesn’t have enough bandwidth.
>
> Dana
> N1OFZ
>
>
> > On Jan 19, 2017, at 11:43 AM, Curt Mills <curt.we7u at gmail.com> wrote:
> >
> > So... Ken, N7IPB, and I redid the scheme and can now receive eight AM
> -or- FM frequencies at once per RTL SDR receiver, using one piece of
> software instead of a pipeline of commands. There are also free audio
> servers where you can send these streams so you don't have to run your own
> Icecast server either.
>
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-- 
Curt, WE7U
http://we7u.wetnet.net
http://www.sarguydigital.com