I am interested in using 4G/3G/2G connection for telemetry mostly. I have not enough space for Raspberry Pi + USB modem, so need something more compact.
I’ve found some 4G modules with UART connection, like 4G GSM/GPRS/GPS TTL MODEM-SIM7600E, but they are all come with GPS, which is large and redundant (we have already separate GPS).
I would prefer using Linux for this offboard controller. Though ready-to-use solutions on any other OS, like nuttX, also may be possible.
Ideally, if controller can also take video via CVBS input and store it on microSD card. There is no strict requirement for good video compression, because I don’t expect strong signal in my area of interest in any case and probably can’t stream video.
Still interested in this…
I’ve found there exists an open source KiCAD schematics for Raspberry Pi Compute Module IO board. Maybe it is simple enough to remove all unnecessary connections and add just 4G module. Maybe in that case raspberry’s camera interface is useful.
I haven’t experience with hardware development and don’t know how difficult this way is and how much it will cost. I would like to have an open solution not only because of fun but also they give more chances for adaptation — for example, in our target application (forest fire monitoring) it is sometimes better to set lower fps rather than lower resolution, and I have seen no ready products providing this.
If someone is interested I would be glad to hear anybody. For now I don’t understand what 4G modules can be placed on PCB and do not cost hundreds of dollars. The best what I’ve seen is https://www.digikey.com/en/products/detail/u-blox/SARA-R422S-00B/14319126, not sure if it’s available in small quantities.
