Wondering about soundcard integration with RadioMail. I see Vara in the "Ideas" lane which I imagine would use some type of soundcard (iPhone or external). Questions that came to mind: Could the iPhone itself generate the sound needed? If so, how would it interface with the radio? I have and use a Digirig external soundcard with my PC and radios for VHF/UHF/HF packet, Vara and other digital modes. Lightning to USB-C cable would connect iPhone directly to Digirig. Does a software packet TNC exist for iPhone? Would the author of Vara be interested in coding an iOS version? I'm just dreaming of possibilities.
The audio system in the iPhone can certainly act as a AFSK packet modem. Several APRS applications include this function. The issue is activating the PTT line, which is usually done with VOX on the radio. This is not really a good solution since few FM radios include VOX, and the ones that do have a fixed VOX delay that is way too long for "connected" mode packet (it works OK for UI frames used in APRS). Connecting a DigiRig or other sound card interface via USB would require writing the drivers for iOS which could get kind of messy or may not even be allowed by Apple. The OS is pretty limited on what types of USB devices are supported. We certainly could build a radio cable that includes a VOX circuit with no VOX delay, and I have been thinking about such a project.
Native Vara support is not going to happen. Vara is a Windows only application and the author has no plans to port his work to other operating systems (and even if he did, iOS would probably be way down the list). Connecting over a network to a Vara instance on another host would be easy enough, but if you had to drag a Windows computer around, why would even use RadioMail? You could build a RasPi with Vara and Packet modems running as an "appliance" connected to a radio, and then just have RadioMail network connect to those modems. But again, that kind of defeats the whole portability function of RadioMail.
-Scott, NS7C
WRT Packet, Scott is correct in the sense that the whole AX.25 + AFSK modem stack could be handled by the iPhone. This leaves the audio i/o and PTT connection to the radio and yes VOX won't cut it for session oriented AX.25 (I tried to make that work and failed). There should be a standard for a simple audio cable where one channel (R) carries audio and the other (L) can be use to issue tones to control PTT. The only downside is that it probably means active circuitry that require some source of power. Also, it's awkward to use a handheld device with a cable attached to it. We're radio people after all, let's have some self respect and go wireless 
Two other options to connect would be BLE or WiFi. A BLE version of Digirig would be a welcome addition (until radio manufacturers decide to wake up and add BLE natively). One can dream. WRT wifi, IC-705 and friends could be supported in that fashion. It's probably a big lift but at least it's possible as demonstrated here GitHub - nonoo/kappanhang: Remotely open audio channels and a serial port to an Icom RS-BA1 server (for ex. Icom IC-705 transceiver).. On the other hand, the Mobilinkd does a very good job as a BLE TNC for Packet, so it seems that anything else would provide only a marginal improvement.
WRT Vara, yes unfortunately Vara is closed source and more importantly a proprietary protocol (which seems like a weird choice to deploy so widely for ham radio use, but I digress). Currently the only path I can see for enabling Vara interoperability is for some enterprising DSP expert to reverse engineer the protocol so independent implementations can be created. Until then, a tiny PC or RPI to run the Vara modem as a headless server is the best that can be done. Below is a picture of my setup using a tiny Beelink T4 (runs on 12V) running Vara modem on Linux. It pains me that an extra computer is required but it still delivers a fairly compact system. The benefit is that you don't need extra keyboard and screen. You can can compose emails on your phone ahead of time, and then walk up to your station and send/receive.
Adding my experience here. I’m using direwolf + Digirig on the km4ack raspberry pi build. Direwolf was compiled with avahi support and with this setup I use my iPhone over wifi as well - this is the closest I could get to a mobilinkd.
There’s another option. You could plumb together direwolf and a serial interface and announce it over Bluetooth. Haven’t seen the need for it since direwolf over wifi really works well - RadioMail just recognizes it as a TCP/IP TNC.
I’ve documented my efforts here: GitHub - dcasati/direwolf-kiss-wifi: Setup direwolf as a KISS TNC over wifi
Very cool to finally see a Winlink client for iOS.
Diego, VE6DPC
Diego, great to hear. Yes dns-sd is magical!
RadioMail implements the support for BLE and TCP TNC discovery as documented here:
https://github.com/hessu/aprs-specs
With serial TNC it's very easy to make them available on a TCP port, simply use nc, for example:
`nc -k -l 8001 > /dev/cu.usbmodem14301 < /dev/cu.usbmodem14301`
and then follow the instruction in the spec to advertise your device via dns-sd. Not as portable as a mobilinkd but could turn an old TNC into a networked appliance easily.
BLE is good. I would like something to carry with me low cost like mibilinkd for packet, but they are not available. I have a P4 Dragon 7400 Bluetooth enabled. Not sure if BT or BLE. It is part of my hybrid gateway. But I could experiment if RadioMail and the 7400 BT protocols are compatible. Radio control and PTT built into the 7400.
Pactor is not supported in RadioMail so don't expect anything to happen. However would be good to know what bluetooth interface they support (could not find anything on their web site). If you use one of the BLE explorer app (like BLE Scanner https://apps.apple.com/us/app/ble-scanner-4-0) you should be able to see if the device gets discovered by the iPhone.
From what I was able to find, the manual for the P4 Dragon says it creates
a virtual COM port under Windows. That would lead me to believe that it is
using Bluetooth Serial Port Profile (SPP) and would not be supported under
iOS, since Apple has not enabled SPP and only allows Bluetooth Low Energy
devices (unless you are a hardware manufacturer that is licensed under the
MFI program).
- Wes W8WJB
OK, this is ugly, but it does work:
iPad with Apple "Camera" adapter (really just lightning to USB)
Masters Communications DRA-70 sound card interface with VOX enabled
TH-F6A
Using one of the APRS apps that has a built-in audio modem
Too many wires, the iPad does not have enough power for the DRA, so you have to plug in a charging cable too. But hey, it does work....
-Scott, NS7C
Wow, super creative Scott, thanks for sharing. Good to know that iOS will recognize an external sound card in that fashion. Could be useful for prototyping...
Found in my notes... https://groups.io/g/FT8-Digital-Mode/topic/86724336?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,40,86724336
by Ron, N6YWU "The FT8 decoder.....FT8 Decoder on the App Store. ..allows decoding FT8 8FSK modulated signals contained in externally provided audio or sound from an SSB radio or SDR. The app can also generate standard FT8 message audio, so can be used to experiment with sending and receiving FT8 encoded and modulated audio. The app does NOT perform Auto-sequencing or encode long hashed callsigns. Enabling VOX works for Tx. "
There is no CAT control support, so you have to tune the radio to the desired FT8 band, and use your transceiver's VOX mode to transmit. The wired connection method depends on your particular radio. The iPhone and iPad TRRS jacks requires certain impedances and levels. Reports are that some of the Elecraft rigs will work with just a splitter and audio cables. I use a Lightning-to-USB adapter plus a mini USB "soundcard" with my small QRP transceivers (QRPGuys Digital FSK III kit and (tr)uSDX units), but plan to build an audio cable with an small impedance plus level matching network to use with Apple's tiny Lightning-to-TRSS-audio adapter.
by Rod VA3MZD....No trouble getting rx to work with iPad and Digirig to an FT818.
