My open ended questions are: 1) What latency would you expect to see from a button push to a wifi transmission (the esp8266 does not need to be asleep/ low power) 2) how much variability would there be in this and 3) what happens if two units try to transmit at the same time.
Would I be correct in thinking that with a dedicated wifi network, transmission ranges of 10 metres max, and possibly just simple UDP connections, we are in the single millisecond range, or is that too optimistic. Results are typical expected to be accurate to 0.01 seconds (ignoring the human element of the button push!!)
Thanks in advance for any info, or indeed any alternative approaches. Similar products exist commercially, but I'm not sure if they take this approach or time 'locally' to each stopwatch and then transmit the results. I know that the 'start' signal is synced across all watches, so its effectively the same problem but in reverse?