IC-705 band decoder now supports external USB transverter control

[Mike Lewis]

One of the main goals in developing band decoders for the Icom radios was to permit external control from PC apps like loggers and WSJT-X and have the band decoder handle the frequency translation along with IO for relays since not all app support transverters, or at least are limited, and PCs do not have IO.

I now have frequency external control via CI-V over USB working on the IC-705 BT version band decoder. The decoder is Arduino and runs on a M5Stack Core or Core2 and with a 2" LCD, 3 buttons and various IO modules. The M5Core3-SE and M5AtomS3 run on BLE only and after some more relatively easy changes those should work as well. I prefer the M5Core2 since it can run both BLE and Classic BT. I prefer Classic BT over BLE because it is fast to reconnect and has been very reliable with the IC-705.

Provided your log program or digi mode app knows about transverter bands or allows non-stock bands, you can specify an offset = 0Hz. For WSJT-X just define the frequency in the main frequencies/mode list, no offset definition required. Normally you would use the usual offsets to get your IF on the radio side in these apps which does work, but also requires a PC/Pi to use them. The decoder can run standalone providing transverter support and IO with a local transverter frequency display and memorizes the last band parameters for each Xvtr band, as well as the last non-Xvtr band used. It also has 3 Xvtr band buttons, no PC required. Add a PC connection only when it is needed for logging or digi-modes.

https://github.com/K7MDL2/IC-705-BLE-Serial-Example

You would use 2 USB connections with a PC, one to the decoder for a USB to BT CI-V bridge with frequency translation. There are no USB audio channels there. The 2nd USB goes to the IC-705 USB connector. You get your audio there. You can use a program like wfView and connect via USB or Wifi to get audio and spectrum, just ignore the CAT control aspect since, like the radio, it knows nothing about the transverter operations.

I tested it with N3FJP AC log and VHF Contest and WSJT_X. WSJT_X standalone with the decoder works well. VHF Contest standalone doing rig control works well. AC log a bit less so, seems like it lacks some rig control, or I have not found it.

What does not work so well is using the logging app and WSJT_X together (a long time problem). They do not exchange complete mode, frequency, and band data, nor equally in both directions live. Logging a contact from WSJT-X does work reliably. Manually logging a non-digi contact is where the lack of good data exchange between them shows up, better or worse depending on who has control of the CAT connection. This does not affect the band decoder and it's IO functionality; just makes you do extra steps to enter or correct frequency data that should be easily available. wfView does not handle transverters today. Basically, any program that is designed with the stock radio bands as limits will always be a problem. I suspect N1MM+ would work well, just set the transverter band offsets to 0Hz. I have never liked the way N1MM+ and WSJT-X worked together (as of a few year ago) so I do not use it anymore. There is a good chance AC Log's incomplete data exchange is a design choice or bug given that VHF Contest works somewhat better, and are basically the same thing underneath. I think AC Log has more of a HF band usage design focus. The inter-program issues mentioned are not related the band decoder, they have always been a problem. Just pointing out the decoder is no magic bullet, but it is a step up overall. There is no standard data exchange used by every program, so each struggle to work together.

This is a big step forward to my vision of adapting an Icom radio to support transverters natively, as compared to a K3, a KX3, or several SDR apps where it is pretty seamless. I can put this into my other band decoders where it makes sense. What may help solve some of these interop issues is to have a decoder hamlib interface, but then you have to have logger and digi-mode program that can talk to 2 hamlib interfaces. Or create a data exchange hub device. Good luck making that work with every major model radio. wfView makes a good attempt with Icom radios. It lacks proper transverter support though.

I am planning to use the 705 as my Rover IF rig in combination with a 3 band Xvr box that is nearly complete. I recently modified my truck DC power system with a LiFePO4 battery in the cab (for now), along with a under cab DC-DC converter that also supplies the cab, battery, camper. The camper solar will connect to the charger and trickle charge the starter battery and the Li battery. This setup gets higher voltage to my voltage sensitive gear, but also provides more camper battery capacity with solar charging. Something a DC booster alone won't accomplish.

The battery sits strapped in on the floor under the rear truck cab seat today. I will likely move the Li battery into the front of truck camper and remove the heavy pair of AGM batteries that sits next to my rear bumper saving a lot of weight and freeing up gross rear axle weight. The only reason to do that is, at least for the colder part of the year, the battery gets dripping wet with condensation as the sun heats up the cab air but the battery stays cold for a long while. That will cause mold/mildew over a short time. No sure wrapping the battery in thin foam, or putting it in a box packed with soft foam, will be enough. The foam would also trap charge/discharge heat. Good in winter, not good in summer. There is no free lunch!


Mike Lewis, K7MDL
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