DSD or DSD+ Multiple Streams?

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kscott

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Is there a way to decode concurrent multiple streams using DSD or DSD+ in Windows? I am using multiple R820T dongles as receivers with Unitrunker and SDR#. I can now only listen to a single digital P25 transmission piping the SDR# output into DSD or DSD+. Nearly all of the systems in my area are now digital.
 

br0adband

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You'd need separate distinct copies of DSD/DSD+ to manage each separate distinct stream you want to decode. You'll reach a limit at some point in how the audio needs to be routed: VB Audio Cable can have up to three instances meaning you'd be able to decode three things at one time, but iirc Virtual Audio Cable (a different product and commercial/pay) offers up to 255 of them so that might be the only option if you have a lot of stuff you need to decode ("a lot" meaning more than three sources/streams).

You can run multiple copies of SDR#, obviously, but a potentially better solution might be to use SDR-Radio as long as the frequencies are within the bandwidth reception of the SDR hardware you're using. RTL sticks have a bandwidth of about 2.4 MHz wide (trying to handle more than that results in dropped samples) so that's not a very wide swatch you can monitor - you could run two copies of SDR# to get double the potential bandwidth, of course, as most trunked systems tend to be inside a 5 MHz reception window.

if you need more than that the upcoming Airspy (from the author of SDR#) will have a 10 MHz bandwidth which should cover most any modern trunked system range without any issues at all, and of course there are much better SDR devices available like BladeRF, the upcoming HackRF (think it's still in development, not sure), and many others. Those higher quality and more capable devices can offer 20 MHz wide bandwidth windows, or even more, sometimes up to 40 or just a bit more. That's a huge window to be able to peek in on... :p

SDR-Radio allows you to handle up to 6 frequencies at the same time using just 1 RTL stick and one copy of the program but you're still limited to that 2.4 MHz reception window. If you ran two instances of it you could monitor 12 frequencies simultaneously with just 2 RTL sticks, and so on. You can read more about that multi-VFO potential of SDR-Radio in the following thread:

http://forums.radioreference.com/software-defined-radio/284267-sdr-maximum-overdrive.html

Very interesting things we're capable of nowadays because of these "cheap USB TV tuners..." :D
 
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