Thanks for the info Curt. I did buy one of those dongles and an going to try the procedure for setting up my APRS radio for proper output according to the instructions on the wiki.
I can see this info pertinent for future use as well. 73 John On Jan 19, 2017 11:43 AM, "Curt Mills" <[email protected]> wrote: > This is off-topic for Xastir/APRS but figured some might be interested. > > I wanted to set up an RTL SDR dongle to receive our SAR frequency > (high-band VHF, FM narrow) and send to an audio streaming server. I did it > with a pipeline of commands on Linux. I mentioned it on another list: > Another SAR guy two counties away (Hi Tom!) mentioned that he wanted the > same thing but with multiple frequencies so he could choose which frequency > to listen to. > > The idea is that SAR members and their family members could attach their > portable devices to the stream and listen to live SAR traffic during the > mission. For SAR members this is most useful on the way -to- a SAR mission: > They can hear the recall code or perhaps more specific directions or > important facts as they are coming in to the search area. All very useful > if they don't own a SAR radio but have a cell-phone (and are in range of > the cell network of course). > > 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. > > I spent one day walking around the house with earbuds in and my cell-phone > listening to a 220 repeater this way. I set up eight 220 frequencies on the > RTL and could choose which audio stream to listen to. Since it was > squelched most of the time and sending samples of zeroes, the cell-phone's > battery didn't get depleted. Note: There is quite a delay with this method, > in my case 20+ seconds from RF to when I hear it in the earbuds, but much > of that is probably audio buffering in the client on my phone. I'm using > VLC on the phone. > > One must patch the RTL_Airband code to send constant samples of zero when > each channel is squelched to keep the audio channels streaming, but other > than that it's pretty simple. 8 AM or 8 FM frequencies can be set up this > way, anywhere between 24 MHz and 1.77 GHz, as long as all 8 are within the > 2.4 MHz passband where you have the RTL tuned. > > If anyone wants to do the same I'm happy to share my configuration, minus > the login/password for my Icecast server. > > Total investment: $25 for a TCXO RTL SDR dongle, and a whole bunch of time > playing and testing until we figured out the magic formula. > > -- > Curt, WE7U > http://we7u.wetnet.net > http://www.sarguydigital.com > _______________________________________________ > Xastir mailing list > [email protected] > http://xastir.org/mailman/listinfo/xastir > _______________________________________________ Xastir mailing list [email protected] http://xastir.org/mailman/listinfo/xastir
