(09-05-2020, 07:45 PM)bcnaz Wrote: This 'may require' a separate carrier service to implement...?
Yes, a paging service account and phone number would be required. There are still nationwide paging networks and the service is very common for first responders and medical/hospital workers.
Would you pay $10/month+a pager module for radio silence until you feel safe to raise your antenna mast like a nuclear submarine on patrol and initiate an outbound call, especially if you can still know what is happening while still not giving up your position to both corporations and the state security apparatus.
https://en.wikipedia.org/wiki/POCSAG
There are occasionally news stories of innocent people becoming suspects in crimes even convicted because the state has no other suspects but their mobile device was detected, triangulated, and logged near the time and place of violent or property crimes. Often these methods are hidden by creating a chain of evidence based upon choosing a preferred suspect and working from there.
(09-05-2020, 06:21 PM)tllim Wrote: You can design a small piggyback board using a microcontroller to control pager chip and communicate with PinePhone thru pogo pin i2c communication. The modem can be hardware disable thru dip switch or you can have write a program disable the modem and acrtivate when plan to use. For sure the program need to factor in the model initialization sequence and works with phone manager driver.
If I can, I hope to lay everything out on kicad then use it as a guide to lay out and connect everything with magnet wire and sandwich that between two strips of kapton tape. It is super sketchy but I have no way to make a PCB that fine and dont want to order out for several revs. It will be wonky as I will be using through hole components for pull up/downs and coupling/decoupling for SM ICs, an attiny should be enough to control that Seiko receiver chip.
But first I/we need to get a breadboard test rig assembled and get access to a SDR though I think this could be done with a sound card audio and transmitter, maybe just mix and feed that to the Seiko POCSAG chip's IF in pin and skip the radio RX stage for breadboarding.
I used to have a DOS POCSAG encoder program though not the source, does anyone know of a FOSS POCSAG encoder for Linux? I recall a pre-built amateur radio repeater add on image for OrangePI and other cheap ARM boards a few months ago that included the encoder for amateur radio paging but I didn't find source for it.