Many people have asked about using audio interfaces like DigiRig with RadioMail. For this to work, two conditions are needed:
1. RadioMail must have an internal modem. The most common one being the AFSK 1200 modem and HDLC decoder used by AX.25 protocol, colloquially known as a packet TNC.
2. An external audio interface where PTT can be controlled from iOS.
Most audio interfaces use serial port control or expose a HID device for PTT control, which aren’t easily accessed in iOS. However, Denis K0TX developed the DigiRig Lite and DigiRig VOX PTT cable to solve this problem. A reliable PTT can now be triggered with a simple side tone on the right audio channel.
This led to the idea of adding a software modem in RadioMail. I'm happy to announce that I've implemented a native AFSK 1200 modem in RadioMail. If you're familiar with this mode, you know the twist introduced by emphasis and de-emphasis in radio can greatly affect decoding, often worse than noise. I'm pleased to report the modem's performance is quite good, achieving about 93% of Direwolf's performance when decoding thousands of frames from track_1 and track_2 of the TNC Test CD, a benchmark for TNCs.
I'm now looking for a few beta testers to help test in real conditions. If you’re interested, please see if you qualify:
1. Be comfortable using TestFlight and installing beta builds (note that if you have a form subscription, you won't be able to access it with the beta build).
2a Have a DigiRig Lite along with an iPhone 15 or iPad with USB-C to plug it in
or
2b Have a DigiRig VOX PTT cable along with a Lightning to 3.5 mm Headphone Jack Adapter to plug it in
3. Have successfully made packet connections to nearby stations. This is important, as often the RF part is what's causing connection to fail, and I can’t help you troubleshoot that.
4. Be willing to upload audio recordings for troubleshooting if needed.
Note that the original DigiRig will not work.
If you're interested, please **message me directly**.