Originally Posted by
Acadi3n
Ok so, we did more testing yesterday on the transponder, and something weird happenned.
Here is what we did. We are using Rev3 transponder design with pre-programmed microchip from Howard. We have installed CT1 (47pF) that was missing, and added a jumper between C4 & R3 on the board to fix missing connection.
We are aware that the loop wasn't completed at the antenna, because CT2 (62pF) was still missing, but we gave it a try under the loop decoder, to see if it would pick up, and it did! but...the transpoder code was constantly changing.
We have seen:
FFFF7F
FFFFBF
FFFFFE (which is supposed to be constant)
FFFFDF
Anyone could explain?
First, get CT2 in there!
I have had the decoder occasionally miss or include bits in the ID on every transponder type I have tried, which is expected as there is no CRC used. (The problem is exacerbated when the transponder passes very slowly under the loop, so I'd guess that adding AGC to the loop amplifier might improve the situation.) However, the correct ID is always detected on the same loop crossing as the incorrect ID, so this won't affect the race result as long as the correct driver is assigned to the correct ID in the lap counting software.