I’m not going to try to define open source. It’s use seems to vary according to what one wants to include or not. Like all things, it’s use can be somewhat subjective.
Here, I’m talking pretty much about the firmware in the device. The app may have some interaction with what I’m pointing to, but it’s the firmware that defines the unit’s interaction with the mesh. If you look through the FCC certification documentation, to me it looks like the firmware defines many of the limits of the unit and these are pretty sharply defined, number of frequencies used, and how they’re used. This is noted in the documentation starting on page 4 at this link: https://fccid.io/2ABVK80085/Test-Report/Test-report-3233950
As a frequency hopping spread spectrum radio. the GTM accesses the limited amount of airtime available in such a way that others are able to likewise do so at the same time without interference. If you dig a little, you’ll find built-in to these requirements are the use of at least 50 frequencies if using 1 watt of power, or between 25 and 50 freqs if using 0.25 watt. Note this distinction as I’ve mentioned it before. If the Py devices are certified at the lower power, then there are fewer freqs available to use. The user may or may not notice a difference there, depending on other traffic. It’s nonetheless one of the regulatory limits I’ve been referring to that affect all users and hence are determined by the FCC, but written in the firmware.
Other measurements of significance seem to refer to how the firmware negotiates its management of access to airtime as its signal is sliced into digital bits and broadcast on many freqs so it can be reconstructed by the receiver. These include, besides RF output, the number of channels used, average time in use, and various measurements that seem intended to ensure adequate performance with digital signals that will not interfere with other users of the spectrum.
There is a range of acceptable values for many of these, but likely little room for some of the most requested changes, like increases in number of hops allowed, manipulation of the transmitter to out of allowed bandwidth, or even operation at higher than authorized power. We know that these are controlled by the firmware and can only presume that, where there was open source code involved, that the end-user would have access to change these values at will.
Concerns over that aren’t restricted to the FCC. goTenna assuredly would want to preserve a positive user experience for those who consume its products. Their chief scientist has explained why uncontrolled numbers of hops quickly makes things unmanageable at higher hop counts. Turn something that would have an easily manipulable hop limit loose at the same time the rest of us are using our GTMs seems a recipe for creating problems for not only other GTM users, but other users of this spectrum.
So I guess my question about how you define open source would be If goTenna permitted access to all the goodies EXCEPT for those limited by the FCC, would it be considered open source? I suspect that we’re most of the way there already on that. If that is the case, goTenna has likely done about as much as it can as a manufacturer - and still be able to produce and sell a 1 watt FHSS device.
Consider that the FCC chases down and seizes CB radios that can be easily modified to operate out of band and at higher power than legal power. I really can’t imagine the FCC keeping that hardware off the market, while making it easy to use soft- or firmware to do basically the same thing with a software defined radio - able to be hacked with a few keystrokes into illegal territory.