[chirp_users] Dongles ?

Angus Ainslie angus at akkea.ca
Tue Feb 7 06:42:10 PST 2017


On 2017-02-07 07:24, Sarge ex 7thAF wrote:
> I hope this is an acceptable question for this list. I don't know any
> other place to ask for this help. A local county emergency manager has
> told me about an inexpensive magic ( to me ) dongle type rf reciever
> that plugs into a usb port. It has a jack for an external antenna.
> Supposedly this device can recieve a huge amount of frequency spectrum
> AND trunked systems that also uses p25 digital signals.
>   If anyone has links to this device that would give me the complete
> info on this thing, I would greatly appreciate you.
> Thanks In Advance.
> 

You want to look for an SDR ( software defined radio ) device. There are 
many to choose from but the least expensive are usually and RTL-SDR and 
can be purchased from aliexpress, dx.com or amazon. For best results get 
an sdr with a temperature compensated crystal.  There are more expensive 
and versatile SDRs out there like the lime-sdr.

To be able to cover all channels in a typical p25 setup you will need 2 
( if you are using RTL-SDR ) of them and at least a dual core i5 to keep 
up with the decoding load and a quad i7 is probably better.

You then need to setup trunk-recording software. For Linux the best I 
found is trunk-recorder, for widnows your on your own. You may find that 
once you've done all this setup the channels are encrypted and you can't 
listen anyway.

Mentioned last but probably one of the things you'll want to look into 
is whether this is all even legal in your area/country. In Canada  for 
instance it's a grey area if you listen to p25 encoded transmissions. 
It's illegal to try and decrypt ( vs just decoding ) radio traffic. In 
Canada it is also likely illegal to record first responders.

Oh, and all of this has nothing to do with chirp.





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