D-STAR on HF

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burner50

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I would think that the SNR on HF would be prohibitive for DSTAR.


In fact thats one thing I dont like about Digital anything (DTV, DSTAR, P25), once the signal starts to degrade, its toast. Whereas on analog you could still pick the voices out of the static.
 

N4DES

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I would think that the SNR on HF would be prohibitive for DSTAR.


In fact thats one thing I dont like about Digital anything (DTV, DSTAR, P25), once the signal starts to degrade, its toast. Whereas on analog you could still pick the voices out of the static.
That is where your thinking is incorrect. The digital FEC, especially on latest versions of P25, is very robust and has virtually no drop-out until you reach the equivalent of 20db SINAD. It is very difficult, if not impossible, to listen to an analog voice at around that SINAD level but the P25 is clear with virtually no digital artifacts. There are 3 to 4 of us that use it every day on VHF during our commute and have repeated results.

Mark
 

burner50

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That is where your thinking is incorrect. The digital FEC, especially on latest versions of P25, is very robust and has virtually no drop-out until you reach the equivalent of 20db SINAD. It is very difficult, if not impossible, to listen to an analog voice at around that SINAD level but the P25 is clear with virtually no digital artifacts. There are 3 to 4 of us that use it every day on VHF during our commute and have repeated results.

Mark


I have no way to refute your claim with P25, as my experience with digital radio is NONE. But I still have some reservations... All of my experience with Digital transmissions is in the Television field, both wire and over the air, and digital fails long before analog.


The Iowa State Patrol started using P25 on their car to car channel, and ever since, they've been using a CIS channel for Car to Car chat instead of their P25 channel. Coincidence? I dont know...
 
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N4DES

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I have no way to refute your claim with P25, as my experience with digital radio is NONE. But I still have some reservations... All of my experience with Digital transmissions is in the Television field, both wire and over the air, and digital fails long before analog.


The Iowa State Patrol started using P25 on their car to car channel, and ever since, they've been using a CIS channel for Car to Car chat instead of their P25 channel. Coincidence? I dont know...
You can't compare analog to digital TV as the FCC mandated that the TV stations reduce their ERP when they went digital and also many stations migrated from VHF to UHF in the transistion as well but still call themselves their VHF channel position. There are too many variables to be able to compare it to a digital radio system, such as P25, that can operate mixed mode from the same location and power output.
 
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N_Jay

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Maybe we need a discussion about S/N, Eb/N0, and the implications of various FEC methodologies in minimizing and mitigating the effects of BER on an encoded bit stream.


Nahhh, that would be boring.
 
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