we experienced recurring but somewhat inconsistent false finishes in a recent race

we use an S4 with an optocoupler between hill wiring and timer

there seemed to be some correlation between our announcer [who was sitting right at the S4] getting excited about certain racers approaching the finish and raising his voice significantly, and false finishes occuring when the racer was too close to the finish to clear the false in time-has anyone experienced anything similar? or could a cell phone that's on cause such problems?

Does the speaker wiring for the announcing system use the same cable as the hill wiring?
Jenna

I spoke with them about this. There is an issue with the AC voltage from the PA either bleeding over onto the timing lines due to a splice, abrasion in the wire casing, etc.

The false finishes only seem to occur when the announcer really got excited on the PA system and pushed it's limits.

Just the facts. Get a calmer announcer.