Hi, we have exactly the same problem and we are no newbies to packet radio modems. The XR2211 decoder should perform much better, than it sometimes does in OT2m. This modem chip is also used in some other tncs... but I did not change it for an TCM3105 or similar in the OT2m -so far no time to test this... However we observe many OT2m units, that show POOR DECODE on 1200baud on different radios and locations. Some only decode less than one third of all heard packets..we do not know why... However, we have also seen some OT2m units that do significantly better than that, running same firmware. We are also aware of the wrong capacitor in the audio filter circuit of some OT2m serial No. batches, but even if we soldered the correct C it is still showing very odd effects with poor decode and digipeater performance. We would be glad to have some solution offered, since OT2m is starting to get widely used in our national APRS network as an intelligent digipeater or replacing old tncs, that could not do the NEWn-n paradigm.
hw? vy 73 de Mike oe3mzc ----- Original Message ----- From: Mark Cheavens To: [email protected] Sent: Thursday, September 10, 2009 3:31 PM Subject: Re: [tracker2] Tracker2/Display & decoding With the modem chip used it is rare that a "weak" or "noisy" signal will get decoded. Is the audio "packet" 9600, 1200, or speaker audio? With 1200 baud packet you need to have de-emphasized (sp?) audio to the modem (TNC). Speaker audio DOES have de-emphasis, as should a "1200" baud port of the radio. (FYI- 9600 had NO pre- or de- emphasis) Just because you can HEAR a packet, does not mean the TNC can decode it. The signal to noise radio need to have a LOT of signal, and VERY little noise. Mark KC5EVE At 01:02 AM 9/10/2009, you wrote: Hi there, I've Tracker2 connected to a Nuvi350 and was wondering why sometime it took a while before I could see some of the callsigns get into the Favorite (after I did a delete all). So, I added an LCD display to my Tracker2 yesterday and found out that most of the time, Tracker2 couldn't decode the packets (i.e. not displayed on the LCD) especially the weak ones. Now I'm wondering what else I need to do .. Anyway, my setup is .. Kenwood TMV71A/Data/BandB <-> Tracker2 with LCD <-> Nuvi. I brewed my own cable between the TMV71A and the Tracker2.. sending packet out does not seem to be a problem. Is there anything in the configuration that I need to do? TIA, Mohd/9W2TPT
