Author Topic: Demodulator is <x>sec behind  (Read 7418 times)

Admin

Demodulator is <x>sec behind
« on: January 24, 2018, 11:02:21 am »
Hi All

Chris Parsons has discovered a problem when the ogn-decode process starts running, it keeps connecting / disconnecting to the APRS servers, the following messages are produced

Quote
Demodulator is 31sec behind ! (4)
Demodulator is 31sec behind ! (5)
Demodulator is 31sec behind ! (6)
Demodulator is 31sec behind ! (7)

The ogn-decode eventually exits and restarts, resulting in the same issue

Anybody know why this is happening ?

Thx
Lee

Richard

Re: Demodulator is <x>sec behind
« Reply #1 on: January 25, 2018, 10:13:58 am »
Lee,
   I think I understand what your asking.... When flying the gliders become visible on SD then keep diapering from the screen for a few seconds then re-appear on screen again. I thought it may just my PAW loosing connection to the server then picking it up again. It seems to be all OGN traffic only, from all stations at the same time (Pocklington, Burn, Ruff,) as I can see all OGN traffic at the same time when Central the the airfields. All other traffic is still displayed OK ( ADSP, Mod S etc.)
Richard.
Europa XS

exfirepro

Re: Demodulator is <x>sec behind
« Reply #2 on: January 25, 2018, 10:45:34 am »
Lee,

Presumably something to do with the dns not syncing NTP properly. Had a search on the OGN Forum and found this thread. Don’t know if it helps - a bit beyond my level.

https://groups.google.com/forum/m/?pli=1#!searchin/openglidernetwork/wrong$20time/openglidernetwork/yjHBg12J7l8

Peter

Admin

Re: Demodulator is <x>sec behind
« Reply #3 on: January 25, 2018, 11:05:12 am »
Lee,
   I think I understand what your asking.... When flying the gliders become visible on SD then keep diapering from the screen for a few seconds then re-appear on screen again. I thought it may just my PAW loosing connection to the server then picking it up again. It seems to be all OGN traffic only, from all stations at the same time (Pocklington, Burn, Ruff,) as I can see all OGN traffic at the same time when Central the the airfields. All other traffic is still displayed OK ( ADSP, Mod S etc.)

Hi Richard,
Not sure what this is in response to ?
I dont think this is related to the thread title
Re: Demodulator is <x>sec behind
can you clarify your point a little more, I don't understand I'm afraid

I think you are asking why the OGN traffic disappears from your display?
What range are you from a Groundstation when this happens ?
Are you simply on the 'edge' of reception from the ground station ?

Thx
Lee
« Last Edit: January 25, 2018, 11:08:56 am by Admin »

Admin

Re: Demodulator is <x>sec behind
« Reply #4 on: January 25, 2018, 11:06:56 am »
Lee,
Presumably something to do with the dns not syncing NTP properly. Had a search on the OGN Forum and found this thread. Don’t know if it helps - a bit beyond my level.
https://groups.google.com/forum/m/?pli=1#!searchin/openglidernetwork/wrong$20time/openglidernetwork/yjHBg12J7l8
Peter

We worked it out, the RTL-SDR was not plugged into the receiver
Thx
Lee

Ian Melville

Re: Demodulator is <x>sec behind
« Reply #5 on: January 25, 2018, 01:05:41 pm »
Do you mean RTL-SDR was not plugged into the RPi ? I thought the RTL-SDR was the receiver.

Admin

Re: Demodulator is <x>sec behind
« Reply #6 on: January 25, 2018, 03:48:46 pm »
Do you mean RTL-SDR was not plugged into the RPi ? I thought the RTL-SDR was the receiver.

correct

Richard

Re: Demodulator is <x>sec behind
« Reply #7 on: January 25, 2018, 04:46:54 pm »

Not sure what this is in response to ?
I dont think this is related to the thread title
Re: Demodulator is <x>sec behind
can you clarify your point a little more, I don't understand I'm afraid

I think you are asking why the OGN traffic disappears from your display?
What range are you from a Groundstation when this happens ?
Are you simply on the 'edge' of reception from the ground station ?


Lee,
   Sorry if i have misunderstood your Original Question I should have posted a New topic.!
Yes all the glider traffic appears and disappears all at the same time, all the glider sights with traffic at the same time. It is as thought there transmitters are all tuned off at the same time. I still receive ADSB, and Mode C,S in there formats are still displayed and do not disappear from screen. Or in-other words while displaying all traffic, Gliders, ADSB, Mode S,C only the Glider traffic disappears. I can be at different range when it is happening. I first noticed it being south of Brighton, Not sure of distance to Burn, Pocklington, Ruff without my map to hand. I did put it down to being out of range but it seems to happen when closer to a gliding site too. ( I still put it down to a range issue, It was just when you asked the Question above it made me think.
« Last Edit: January 25, 2018, 05:17:20 pm by Richard »
Richard.
Europa XS

Admin

Re: Demodulator is <x>sec behind
« Reply #8 on: January 25, 2018, 05:28:12 pm »
Hi Richard

I have started a discussion on what you have raised here :-
http://forum.pilotaware.com/index.php/topic,1147.0.html

Thx
Lee

exfirepro

Re: Demodulator is <x>sec behind
« Reply #9 on: January 25, 2018, 11:18:02 pm »
Lee,
Presumably something to do with the dns not syncing NTP properly. Had a search on the OGN Forum and found this thread. Don’t know if it helps - a bit beyond my level.
https://groups.google.com/forum/m/?pli=1#!searchin/openglidernetwork/wrong$20time/openglidernetwork/yjHBg12J7l8
Peter

We worked it out, the RTL-SDR was not plugged into the receiver
Thx
Lee

Always turns out to be something simple in the end  ;) :-\

Peter