Page 1 of 1

Using GM300 to decode Pocsag? can it be done?

Posted: Sat Jul 12, 2008 8:00 am
by Essexsaxo
Hi all,

I'm new to the group, I've had a crack at decoding some pocsag data using the discriminator from the rear connector and my PC running PDW pocsag decoder and the audio seems a bit load and over modulated. I've been transmitting Pocsag with this radio and it works wonders. Has anybody had any results with using these radios to decode?

Nick

Re: Using GM300 to decode Pocsag? can it be done?

Posted: Sat Jul 12, 2008 1:26 pm
by ve3nsv
Are you using Pin 7 and Pin 11 for the receive audio with the internal jumper set to DISC? Can you just not turn the LINE IN level down in the Recording Tab of the Volume Properties?

I have used a CDM1250 and CDM1550 for both Trunker and PDW and have had no issues at all. The computer I use has a Crystal Audio chipset.

Re: Using GM300 to decode Pocsag? can it be done?

Posted: Sat Jul 12, 2008 1:45 pm
by Essexsaxo
Hi,

Yeah i'm using pins 7 and 11, do you know which jumper is for the discrim? I've tried playing with the audio with the computer settings and it still doesn't seem right compared to my scanner.

Nick

Re: Using GM300 to decode Pocsag? can it be done?

Posted: Mon Jul 14, 2008 8:16 am
by motorola_otaku
JU551 on the command board. Position A is unmuted/flat (discriminator) and position B is muted/de-emphasized. Muted/de-emphasized is what you want if the audio you have now is too "loud", but I don't know how much the de-emphasis process might affect your decoding.

Re: Using GM300 to decode Pocsag? can it be done?

Posted: Tue Jul 15, 2008 9:27 pm
by Essexsaxo
Hi,

Thanks for your help, I've added a 10k resistor in line on the data output and it seems to work a bit better, I may have to try different values. The GM300 is absolutly brilliant for sending Pocsag messages.

Nick

Re: Using GM300 to decode Pocsag? can it be done?

Posted: Wed Jul 16, 2008 9:22 pm
by Will
Nick you may need a DC de-coupling capacitor as well as the 10K resistor.
There is DC on the DISC and Filtered audio output from the OPamp.

Re: Using GM300 to decode Pocsag? can it be done?

Posted: Thu Jul 17, 2008 9:22 pm
by Essexsaxo
Thanks will, i'll give it a try