There are many systems. The most common is via a cellular phone modem.mkewman said:are they programmed by hardwire? or over the air? digitally? how?
and if over the air, what frequency? is it encrypted or is it possible to decode it?
is it via edis?
If I'm not mistaken (and I often am...)OES5183 said:Some of the oldest have to be physically programmed at the site by an employee.
RolnCode3 said:I thought I had read somewhere that some of the boards could be changed from the CHP patrol cars...like they had some device that they could drive past the board and change what it said...anything along those lines at all?