This module seems to work fine on the client side, except that APRSISConnector.js requires some nodejs specific modules (net and readline). Is it possible to only include that file when running on nodejs? I'm currently using Webpack, but would be open to something else if you have another suggestion.

Didn't look closely enough at the existing Telemetry class tests when I wrote the Base91 parser. You're using true/false, mine used 1/0 for the digital values. PR incoming to fix it.
Also realized that adding the telemetry object to both Position and MICEPosition was redundant, so I've removed it from MICEPosition. Wasn't breaking anything, but this is cleaner.

I was playing around with this package this morning, just trying to capture and parse my own data for a private project I'm working on. Kept running into the Error when parsing altitude error found here

I am using APRSDroid and just sending packets from my phone. What I noticed is that the app is sending my altitude over as /A=-00072. This doesn't appear to work with the regex match: altitudeString.match('^[0-9]{6,6}$'). Seems that it is failing in two places, first being the - character. I am on the coast in a flood zone so my location is actually below sea level, and the second is that the matcher here is looking for exactly 6 digits and my altitude only has 5.

I was able to resolve this by changing the regex to '^-?[0-9]{5,6}$' which makes the - optional and will accept 5 or 6 digits for the altitude. I'm not sure if this is still accurate but it appears to be working. After changing the regex and running my script again I can now see the Position in the parsed message.

Do you think this is a valid fix for this problem? Why does the current implementation require a positive altitude of exactly 6 characters? I'll admit, I didn't dive deep enough to see if allowing negative altitudes would cause any other problems in the project. Was just curious if this would be something worth updating?

Add base91 compressed telemetry per the spec found here: http://he.fi/doc/aprs-base91-comment-telemetry.txt

I've started working on this over in my fork here but am unsure of the best way to proceed and could use some advice from those more familiar with this codebase. Here's where I'm at:

After rereading the spec, base91 TM can occur in the comment field of all three position report types (uncompressed, compressed, and MIC-E). I've broken the parser out into its own class instead of shoving it in the MIC-E position parsing. The commit referenced above just adds the new parser to the end of the parser list. When used like that, it ends up replacing the Position object in data with a Telemetry object, which is broken. For example, the previous parser:

N0CALL>APRS,qAR,IGATE:!6304.03NN02739.63E#PHG26303/Siilinjarvi|"p%T'.agff|
APRSMessage {
  from: Callsign { call: 'N0CALL' },
  to: Callsign { call: 'APRS' },
  via: [ Callsign { call: 'qAR' }, Callsign { call: 'IGATE' } ],
  raw:
   'N0CALL>APRS,qAR,IGATE:!6304.03NN02739.63E#PHG26303/Siilinjarvi|"p%T\'.agff|',
  data:
   Position {
     latitude: 63.067166666666665,
     longitude: 27.6605,
     symbol: 'N#',
     extension:
      PHG { heightFeet: 640, gaindB: 3, directivityDeg: 0, powerWatts: 4 },
     comment: '3/Siilinjarvi|"p%T\'.agff|',
     msgEnabled: false } }

With the new parser in the list:

APRSMessage {
  from: Callsign { call: 'N0CALL' },
  to: Callsign { call: 'APRS' },
  via: [ Callsign { call: 'qAR' }, Callsign { call: 'IGATE' } ],
  raw:
   'N0CALL>APRS,qAR,IGATE:!6304.03NN02739.63E#PHG26303/Siilinjarvi|"p%T\'.agff|',
  data:
   Telemetry { id: 170, analog: [ 415, 559, 5894, 6348 ], digital: [] } }

So that was dumb. When I look at this now, I feel like this telemetry makes most sense as a PositionExtension. Those parsers get called on position messages, and work by parsing the extension and removing the string from the comment. As far as I can tell, those parsers are only looking for one extension, though. Base91 can occur alongside some of the position extensions (see the packet above with PHG extension and base91 TM).

Any thoughts on the best place to integrate this?

I haven't had a chance to troubleshoot this one yet... but aprs.fi parses this location just fine, but npm-aprs-parser does not (doesn't return a data object):

AF6HO-2>SWRTSY,WIDE2-2,qAR,WA5ZNU-10:'2[^""qj/]"4)}

It can be found on aprs.fi with the timestamp 2017-02-27 12:15:20 CST
http://aprs.fi/?c=raw&call=AF6HO-2