#time-sync.
Posts on the Alpisto engineering blog filed under #time-sync.
- 01#flybeeper #fanet #ads-l
One radio, two networks: how my FANET vario splits each second with ADS-L
My vario has one radio and two networks to serve. Every second it has to decide which network to listen to and when to transmit, and that decision affects who you see on the map. Bench results: if the vario listens to ADS-L for the whole second, FANET reception drops to zero; if it stops listening to ADS-L, it receives 40 to 140 % more FANET frames; if the ADS-L listening window is cut from 550 to 300 ms, the share of seconds in which another maker's transmitter is heard falls from 61 % to 34 %.
13 min read - 02#flybeeper #fanet #ads-l
Teaching a LoRa vario to hear ADS-L, and finding the time to do it
An ADS-L receiver must know when each UTC second starts, and receivers normally get that from GNSS. My vario has no GNSS on purpose: its position comes from the pilot's phone. So I took the time from the phone too, over Bluetooth, and measured how accurate that is. It is accurate enough, with room to spare: the share of frames the device caught went from 15 % to between 50 and 100 %.
19 min read