I'm pondering creating a method over ANT+ to resend data that was missed from the sensor. I think this is pretty doable without big changes to the ANT+ profile for at least the previous 256 messages by just keeping track of missed message numbers and asking them to be sent again via an acknowledge message. Our Moxy sensor only updates every 2 seconds and the profile broadcasts at 4 Hz so there's lots of time to fill in missing data.
However, I don't see a good way to get the missing data into the FIT file. I can do a good guess of when the actual measurement time was based on the message number and the known 2 second update rate. But the fit contributor only seems to allow "Now" data to be written. Does anyone know a way to make this work nicely?
One application for this would be swimming. When the swimmer gets out of the water, the last 512 seconds of data could get passed to the watch.
I think some HR straps do this already.