30 January 2010

More changes to mobile APRS

After much consideration I decided to keep power to the GPS16 receiver permanently. The reason is my intention to eventually install a car PC. The second is that I would like to come up some sort of arrangement that will activate the APRS should the car end up being driven by someone other than me and parked where it might not be easy to find. This would probably involve some sort of device that I would carry and be detected. If the car is started and driven without the device being detected, the APRS turns on and remains on until I intervene. The device would probably be an RFID or somesuch. The car PC would also log all GPS activity at all times.

To allow for GPS connectivity to a PC, I made and installed a splitter between the RS232 GPS and the OpenTracker+. The splitter simply feeds RS232 signal from GPS to two outputs. This was tested with the APRS running and the netboook connected through a 4 port USB-to-RS232 device at the same time and it worked fine. I will need to make sure that the car PC and OT+ can't both talk to the GPS at the same time or something will collide. There shouldn't be any need for either to TX to the GPS anyway.

Still looking for a VGA LCD display that can be powered from 12V, around 10". I could buy an old laptop and hack the display to extend it from the body, but I'm not sure what cable length I could use before it becomes unstable. I suspect it wouldn't be much. I refuse to install an inverter just to power a mains-powered LCD! There are some in-dash displays available but the price is just way over the top for a project like this and besides, I can't install in-dash in the work vehicle.

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