DSD+ Decodes LV

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737mech

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Ok just scanning around with DSD+ found a few new things.
451.25 NXDN48
451.95 NXDN96
462.1375 NXDN96
463.625 NXDN48
451.05 NXDN48

And a really cool one right now 446.8 +D-STAR (Seeing decodes not hearing anything yet) Maybe need to tweak dsd+ ??
Didn't know D-STAR was in town??
 

br0adband

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Those frequencies for the NXDN traffic are all wrong. ;)



A lot of it is for Rebel Communications, they have several licenses here in this area, but they all use the 3.125 kHz offsets (+ and -) so if you don't get the exact frequency all the way out to 6 decimal places you won't get a decent decode most of the time. And of course Nevada Ready Mix has their 800 MHz NXDN system as listed as well, but that's about everything I've picked up and logged for NXDN comms here in Las Vegas in the past few months. Doesn't mean new stuff won't appear, of course, 'cause it most likely will. Never seen it used for railroad traffic around here yet even in spite of it being popular for those purposes.

Stuff in the 460 range is either The D downtown (across the street from me, basically) or Luxor (which I'm sure I'm too far to get a signal from). The D has a lot of traffic at 463.621875 (-3.125 kHz) and 463.628125 (+3.125 kHz from the licensed frequency of 463.625 but they have others as well).

And for D-Star, DSD+ doesn't do audio decodes of that protocol, it just decodes any data stream meaning textual messages, etc. It's pretty rare to catch anything being used on that Ham frequency, D-Star just doesn't seem popular in our area at all. The custom v1.7 of DSD can do D-Star audio decodes, however.
 
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737mech

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NXDN

So don't believe what dsd+ is reporting? I don't understand I can hear traffic on those NXDN systems? Why does DSD+ label them as NXDN48 or 96 if in fact they are not? Or they are and freq close enough for the scanner? And the D-Star as well?? Check pic below what is this?
 
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br0adband

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I can't speak for what you're hearing at this point, and since I don't have an actual scanner (which has a more limited resolution, no more than 4 decimal places) you may be able to get a signal that DSD+ can actually decode using a discriminator tap - all I'm saying is that the actual broadcast frequencies are the ones I just listed in those images and unless I tune them precisely as listed with SDR# I won't get a decode with DSD+ at all, even if it's just a hair off the frequency. The licensed frequencies are just that: what they are licensed to use but because of the narrowbanding initiative plus the fact they can squeeze two channels/slots into the spacing it means they are actually broadcasting based on the offsets which I've discovered are 3.125 kHz above and below the licensed frequencies.

Seems all the NXDN hardware in the Las Vegas area are from the same supplier hence them all using the same offsets, or at least that's my belief. While a handheld or base scanner might be able to tune something like 463.6250 easily, it won't be so easy to tune 463.621785 or 463.628125 precisely which is what's actually being used for transmissions. SDR hardware can obviously tune that accurately, at least with SDR# and SDR-Radio and others in my experience.

As for D-Star, you're getting the text based information aka the ID related stuff that is sent when a mic is keyed on a D-Star transmission. If you look at that "wall of text" there you can pick out the callsigns of the Amateur Radio aka Ham operators doing the transmissions. But DSD+ cannot decode the audio portion, that would require using that DSD v1.7 build (there is a Windows build available someplace).
 

737mech

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Ok I get all that, it makes sense. Maybe the scanner has a bit more slack than the SDR?
So this is a ham operator using D-Star? Interesting. Sometimes I think it may be convention guys showing off new radios and stuff. Temporary stuff in the P25 has happened during some of the big conventions.
 

br0adband

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Well yeah it's Amateur Radio, never seen a business using D-Star in this day and age, and besides, look at the frequency you were tuned to: 446.800 MHz, that's in the 70cm Ham Radio band (420 to 450 MHz).
 
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