P25 channel 0-0 question

millam

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DSD shows channel 0-0 and when it is in use channel no is shown and and no
audio is sent to the speakers.
FCC Callsign: WQTS955 (Ozark, City of) Alabama
Below is what DSD sends to the p25 data file.
--------------------------------------------------------------------------------------------------

Network: 0000A.00A

Bandplan #0: Base=769.83125 Offset=+30 Spacing=12.5 BW=12.5
Bandplan #2: Base=851.00625 Offset=-45 Spacing=6.25 BW=12.5 Slots=2
Bandplan #8: Base=769.83125 Offset=+30 Spacing=12.5 BW=12.5 Slots=2


Site: 1.1 NAC=00A

Channel 0-0: 769.83125 VOICE
Channel 0-112: 771.23125 SCC VOICE
Channel 0-184: 772.13125 CC
Channel 0-220: 772.58125 SCC VOICE


--------------------------------------------------------------------------------------------------
 

mtindor

OH/WV DB Admin
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Carroll Co OH / EN90LN
DSD shows channel 0-0 and when it is in use channel no is shown and and no
audio is sent to the speakers.
FCC Callsign: WQTS955 (Ozark, City of) Alabama
Below is what DSD sends to the p25 data file.
--------------------------------------------------------------------------------------------------

Network: 0000A.00A

Bandplan #0: Base=769.83125 Offset=+30 Spacing=12.5 BW=12.5
Bandplan #2: Base=851.00625 Offset=-45 Spacing=6.25 BW=12.5 Slots=2
Bandplan #8: Base=769.83125 Offset=+30 Spacing=12.5 BW=12.5 Slots=2


Site: 1.1 NAC=00A

Channel 0-0: 769.83125 VOICE
Channel 0-112: 771.23125 SCC VOICE
Channel 0-184: 772.13125 CC
Channel 0-220: 772.58125 SCC VOICE


--------------------------------------------------------------------------------------------------
Yes, that is normal. If you look at Bandplan #0, the base freq (lowest in the bandplan) is 769.83125. So if that is active on some system it is going to show as either 0-0 (Phase 1) or 8-0 (Phase II)

And if you go by the bandplan, spacing is 12.5 khz.
(769.83125 - 769.83125) / .0125 = 0
(771.23125 - 769.83125) / .0125 = 112
(772.13125 - 769.83125) / .0125 = 184
(772.58125 - 769.58125) / .0125 = 240

Mike
 

millam

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Messages
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mtindor read the first line of my my entry please. """
DSD shows channel 0-0 and when it is in use channel no is NOT shown and and NO
audio is sent to the speakers. """""
 

mtindor

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It is probably data or a BSI (base station identification), which usually occurso n the lowest active frequency. Hard to tell by looking at P25Data, which would not provide any useful information. A screen capture of your Event Log Window, or the tidbit from your log files where the logs show that occurring might be helpful.

You'd never here either data or BSI over your speakers.

Mike
 

millam

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Working on both, this site fades during the day, waiting till early tomorrow. Also gonna see what Unitrunker tells me.
 

mtindor

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Location
Carroll Co OH / EN90LN
DSD shows channel 0-0 and when it is in use channel no is shown and and no
audio is sent to the speakers.
FCC Callsign: WQTS955 (Ozark, City of) Alabama
Below is what DSD sends to the p25 data file.
--------------------------------------------------------------------------------------------------

Network: 0000A.00A

Bandplan #0: Base=769.83125 Offset=+30 Spacing=12.5 BW=12.5
Bandplan #2: Base=851.00625 Offset=-45 Spacing=6.25 BW=12.5 Slots=2
Bandplan #8: Base=769.83125 Offset=+30 Spacing=12.5 BW=12.5 Slots=2


Site: 1.1 NAC=00A

Channel 0-0: 769.83125 VOICE
Channel 0-112: 771.23125 SCC VOICE
Channel 0-184: 772.13125 CC
Channel 0-220: 772.58125 SCC VOICE


--------------------------------------------------------------------------------------------------
As others have pointed out (in private to me and publicly), it was probably a simple voice call. If it wasn't encrypted but wasn't heard, maybe DSDPlus is having difficulty tuning to that freq based upon the bandplan. I don't know. I'll let others do the commenting on it from this point forward.

Mike
 

millam

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Jan 18, 2005
Messages
319
Its not in RR database thats why I posted the callsign. When the system transmits on ch 0-0 DSDPlus FL
does not tune FMPA to that freq. DSDPlus tunes FMPA to the other 2 channels and sends the audio to
the speakers, and no it is not encrypted and is not a bsi. This site is weak and I can only get a good signal
when skip is in. Its only 22 miles but elevations keep it blocked. If I ever get it mapped out I will submit
it to RR. Others keep saying its on the Alabama AIRS (new AFRN) network but I don't think so. Is there anyway
to look at the data sent out and verify that it is connected to the AIRS network? I am an old PTT and adjust the
squelch guy and don't know squat about digital. When skip is in I will see what Unitrunker does with it. I have
just started to play with the windows version of SDRTrunker.
 

GTR8000

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BEE00
While it's certainly possible to have a Ch 0-0, I would say that it's fairly unusual, especially for a 700/800 MHz system. Most systems operating in the 700 MHz band use a fairly standard band plan that starts at either 769.0 (Harris) or 762.00625 (Motorola), vs starting at the first traffic channel like this system does with 769.83125.

In any event, I wonder if DSD+ won't tune to that channel because it considers 0-0 a null value and therefore not valid?

It appears that there hasn't been any TDMA activity at the site yet, so Unitrunker would be able to decode the FDMA voice traffic. I would get a signal and voice receiver setup for next time you pull it in, see if it tunes to 769.83125. SDRTrunk 0.5.0-alpha3 is also an excellent bit of software that runs great on Windows, so give that a shot as well.
 

millam

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Jan 18, 2005
Messages
319
Control channel rolled to the 0-0 slot. I won't be able
to play with it again till next week.
 
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