State Hwy Message Boards

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mkewman

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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?
 
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N_Jay

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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?
There are many systems. The most common is via a cellular phone modem.

It could be on a commercial radio data network, a private radio data network, by phone line, by pager, by FM-SCA, by microwave, by RF data link, etc.

What is "edis"?
 

WD8CZP

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The CMS (Changable Message Signs) are run by DOT (CALTRANS) and are a mixed bag of technology. Some of the oldest have to be physically programmed at the site by an employee. Others are programmed from the TMC (Traffic Management Center). I know of none that are radio or over the air programmable. EDIS is the Emergency Digital Information Service (http://www.edis.ca.gov) run by State OES available for all authorized government officials to send direct to the (world) informational news & even Emergency Alert System (EAS) Bulletins. Over the next year, EDIS will be upgraded to handle all the state-activated EAS using VoiP digital technology in addition to text & image files. The website offers some links to 3rd party providers to send EDIS on to wireless devices & email. We also have a packet outlet (text only) on Diablo using AX.25 protocol on the broadcaster RPU channel (450.0375) which also links into So Bay via Mt Umunhum (37.380) - no PL on either. System is up/dn while undergoing upgrades.
 

RolnCode3

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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?
 

csuh13

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OES5183 said:
Some of the oldest have to be physically programmed at the site by an employee.
If I'm not mistaken (and I often am...) ;)

Some of the older ones used a TRS-80 Model 100 as the interface in the control box to change the display... The worker would open the box, and type the new message into te M100 and then drive on to the next sign
 

WD8CZP

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I think they've upgraded from the Model 100's, but still have to use a similar device.

In answer to Mark's question. I am one of four Amateur licensed Communications Coordinators for State OES. I usually am more active as I operate out of a comm center where I monitor six scanners, 2mtr, 220, 440 and have HF available not to mention several special phone circuits as part of my job of Emergency Public Information which includes EAS & EDIS. Net traffic is usually handled by our ACS reserves.
 

mkewman

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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?

i read somewhere that the new CHP cars are getting that capability i think.
 
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