Getting packet fine time information for services / travel-time monitoring purpose

[disk91]

Currently as seen from the LNS, we just have a gateway time with a precision at second, this is limiting the ability to understand and monitor performance for a LNS owner. It's also limiting our ability to debug the RX windows potential problem and creates a doubt on it.

I would like to propose two things:

1 - On HPR add a metadate like HPR_RX_TIMEMS containing the HPR ms time base reception timestamp for each frame

2 - Make Duration fine_time_since_gps_epoch populated by HPR from fine timestamp provided by the gateway (ms scale)

Rq about the 2, I don't know what gatewary-rs push to HPR and if we have this, we have such information for POC data, so potentially it could be in the packet sent to HPR.