[aprssig] Options for robust digipeaters

[Scott Miller]

> Tracker4 - Had good experiences in the past with Argent data stuff (most of our vehicle-based tracking systems are the original OT1). Not kept up with the T4, looks interesting but no iGate so the WX3in1 would win there.

The T4 does function as a standalone IGate. The biggest issue with it at 
the moment is that there's some kind of bug in the Silicon Labs WiFi 
module that causes it to periodically drop the connection, but only with 
*certain* access points - including the old Linksys here in the lab. The 
period is usually on the order of several hours, and is always an 
integer multiple of (I think) 10 minutes. So if you've got an AP it 
doesn't like, you'll see the connection periodically drop and then it'll 
automatically reconnect and connect to the APRS IS again, but it'll miss 
traffic for 10-20 seconds in the meantime.

It's mostly just a nuisance. Unfortunately it's something I can't fix 
from my side, and SiLabs was not terribly responsive *before* the 
pandemic. I'm not holding out a lot of hope that it'll be resolved soon.

We're also understaffed here thanks largely to Covid, and repeaters are 
selling way better than trackers these days so what development time I 
can manage has mostly been focused there. The new repeater controller 
and the T4 share much of the same code base, though, so work on one 
often spills over to the other.

For the next iteration of the repeater design I'm ditching the SiLabs 
WiFi module and going with a wired Ethernet interface with the protocol 
stack resident in the dual-core host MCU. No more being reliant on a 
black box that's been virtually abandoned by the manufacturer. It'll 
also have a GPS port on it, which will effectively make it a superset of 
the T4.

I'm not sure what I even want to call that device at this point - it's 
been the ADS-SR2 repeater so far, but it's more of a Swiss Army knife, 
with simplex, cross-band, and duplex repeater functions, EchoLink 
gateway, sound card interfaces, and various other feature modules that 
you configure through a browser-based block diagram interface, sort of 
like Labview. That part is finally coming together and I'm really 
pleased with how it's working out. If anyone can think of a good name 
for it, I'll send you a freebie when it's in production! ;)

Scott
N1VG