Feature Requests: Configuration Profiles; Stereo-split PTT/TX; TEMPn-N Digi

[KC8HQX]

First, I'd like to say APRSdroid is a fantastic tool, keep up the great work. For future revisions, the following might be useful:

1. Multiple/selectable configuration profiles. For example, the ability to create and store a "normal" profile, one best for working ARISS, one for TCP/IP only, one for sparsely covered areas, different smart beacon settings for different modes of transportation, etc. This would make APRSdroid more user friendly when switching between various use cases and possibly encourage more responsible use of the APRS system.

2. Second audio channel PTT. Assuming most Android devices have sufficient audio channel crosstalk isolation, it might be possible to use the left audio channel for AFSK and reserve the right for keying. If the program generated a constant "key up" tone (800 hz for example) on the right channel, it would be trivial to build a cable that pipes this to a small circuit that could rectify the audio and use it to switch a PTT circuit. This would be much faster than a traditional in radio VOX circuit and would give APRSd cheap, direct control over TX switching.

3. if you do successfully implement full Digipeater functionality, include true TEMPn-N Ad Hoc capability. This is useful for Field Day and general emergency conditions and is arguably more suited to lightweight, portable solutions like APRSd than megabuck Kenwood D7xx series mobiles.

[ge0rg]

Thanks very much for your feedback! Unfortunately, my time is very limited lately, so I can't promise anything.

Profile support is tracked in #68 (from 2013)

Digipeater is tracked in #89 (2014)

I'll keep this open for the split-channel stereo PTT/TX, but the code I'm using for AFSK generation is from https://github.com/jazzido/PacketDroid which is based on multimon and has not been touched for four years. I have no idea how hard this feature would be to implement in multimon...

[ge0rg]

Sorry, I have to correct myself. The decoder is based on PacketDroid, but the encoder is using my fork of https://github.com/nogy/jsoundmodem which is even older ;-)

In jsoundmodem, the audio format needs to be changed from mono to stereo and the data encoding needs to be parametrized to allow for left/right/both channels, which needs to be properly tested in the end.

[ricovangenugten]

Hi, I've been using APRSdroid for some weeks now, works like a charm, thanks!

As far as PTT switching using audio is concerned: I think a minimal implementation could be done without software changes. Since the AFSK itself consists of two sines without pauses/silence you could rectify it and use it to switch PTT directly.

In a fancier application a separate sine wave on the right channel could be used to control the delays between PTT up/down and AFSK output, but currently the preamble could be used for that. If the PTT switches off too quickly or is jittery a small RC circuit could be added after the rectifier.