APRS Decoding FTM-400XDR

[tweiss3]

I've been bench testing a FTM-400XDR that came in while I wait on extension cables. One of the reasons I got it was for APRS, since I have been on the road much more lately. I have it working well, getting position of other units, filtering out weather stations, etc.; however, the "comments" area appears to be junk.
For example read as follows: (8/02/2021 MP01:18)A12|!'&5L|!wd_!3
Looking at the same station on aprs.fi: Battery: 13.918 Volts, Temp: 49.850 Deg.F

Is this normal? Am I missing something, or a setting? My own transmitted beacon appears correct on aprs.fi.

 

[vagrant]

Telemetry data should be preceded by the letter "T" and is a different format/layout than what is on the first example. I am not sure what that is on the first line other than the date and A12 (1200 bps). Your first example line is not telemetry. The second line you pulled from aprs.fi is parsed telemetry, so people can easily read it.

You could read this PDF for more APRS fun, but that data may be information only the sending station can parse. Please note that I am not an APRS expert, not even close.

 

[AK9R]

The Yaesu and Kenwood APRS radios use what's called MIC-E encoding. The transmitted data is encoded in order to make the packets smaller. See section 10 of the APRS Protocol Reference (http://www.aprs.org/doc/APRS101.PDF).

 

[talkpair]

Example 1 looks like MIC-E telemetry data. Because position reports are the only data type MIC-E will support, there is no way to filter them with the FTM-400 since the telemetry data resides in the comment field of the position packet. I don't really see these packets very often. It's discussed in the document AK9R and vagrant posted.

If Example 2 actually uses the telemetry data type identifier, you should be able to filter it using option 3-APRS FILTER and use the packet type OTHER.
It looks more like it is simply comment text of a position packet. In that case, there is no way to filter it out without losing the desired stations.

 

[K5MPH]

It is status data sent from the tnc and is normal some info on some APRS systems can be changed and some not ............

 

[tweiss3]

It's making more sense now. This thread lead to tons of experimenting with the filters and setup, as well as another side APRS project I'm putting together at the house.

Thanks for all the pointers/information.