Author Topic: I have some question about POCSAG decoding  (Read 894 times)

BH9DNV

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I have some question about POCSAG decoding
« on: 22 Nov 2018, 15:12:49 »
Hi everyone:
I have some questions about POCSAG decoding. Our country's railways and high-speed railways have a device that uses POCSAG to pass their position to ensure the safety of railway workers. Similar to the ADS-B of a civil aircraft, I use RTL-SDR to receive and use PDW. 3.2b01 decoding, but my computer can not decode, I can try it on other people's computer, the detailed parameter of decoding success is ?POCSAG-2 NUMERIC 1200?, if anyone can help me, please contact me thank you!

VidarParry

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Re: I have some question about POCSAG decoding
« Reply #1 on: 22 Nov 2018, 19:38:01 »
Hi,
Can you provide more information of your configuration? eg for most reliable decoding you should use  discriminator tap and the USB interface. Radio signal strength is also a factor if the source is moving.

I have no knowledge of RTL-SDR, so that could be an unknown factor.

Cheers
...Steve

BH9DNV

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Re: I have some question about POCSAG decoding
« Reply #2 on: 23 Nov 2018, 16:50:45 »
Thank you for your reply to my message:
For the signals from trains,I can tell you some details
Frequency:821.2375MHz
Coding mode?POCSAG
Rate:1200bps
Data transmission mode: synchronous data transmission mode.
=======================================
When someone else's computer receives and decodes
The content displayed by PDW is ?POCSAG-2 NUMERIC 1200 XXXXX XXX XXXXX?XXX means only the right number of messages
=======================================
In my computer
When i received the signal,Only POCSAG1200 will be displayed above the PDW software.
nothing has been decoded.I don't know what's going on.Maybe there's something wrong with RTL-SDR.

VidarParry

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Re: I have some question about POCSAG decoding
« Reply #3 on: 25 Nov 2018, 07:40:37 »
Hi,
Please provide details of your hardware connections/setup from the RTL-SDR to the PC - how are you connecting the RTL-SDR to the PC? Is it a discriminator output from the RTL-SDR?

I'm going to be offline for a couple of weeks so hopefully someone else will be able to assist you in the meantime.

Suggest you have a good look through Rene's discriminators.nl site and the PDW documentation as well.

Cheers
...Steve

BH9DNV

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Re: I have some question about POCSAG decoding
« Reply #4 on: 25 Nov 2018, 15:17:23 »
hi
I use POC32 to solve the problem. When I receiving the same signal, the PDW displays scrambled code or tone only, but POC32 can decode normally. I don't know what happenen, but I hope to upgrade the PDW again.