Originally Posted by
mv4wd
Hi Howard, thanks for your design, I'm working on my design and I'm facing 'wrong' sequences when I swipe (manually) the transponder across the loop. Fixed transponder causes about 100% good readings. Mostly the error seems to be a missing zero bit (no reverse). To give an idea 1600 of 2000 packets are correct (considering the full length of the frame). Also the errors are located in two 'burst' of wrong packets (maybe wire crossing?). Do you have any number to check if I have to debug further or the values seem 'right'. At the moment I'm spitting out every packet I receive, without any check for repetition. The wrong packets do not repeat in sequence.
Missed bits are unavoidable, and are especially prone to occur during low reception levels (at the edges of the loop, for example). That's the reason to look for three identical data receptions in a row before accepting the transponder as valid. Even then, there will be a few spurious receptions, where three identical but incorrect receptions will occur in a row. At that point it is up to the lap counting software on the PC to determine if the transponder is valid (in other words, one of the participants in the race). If not, then the lap counting software should ignore them.