#ads-l.
Posts on the Alpisto engineering blog filed under #ads-l.
- 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-vario #fanet
The lift does not fade: where 11,046 competition thermals end and how to see it coming
In 11,046 competition thermals the lift hardly fades: pilots climb at full rate almost to the top, so your own vario cannot warn you. The pilots who left before you and the day's earlier tops can, about a minute ahead.
11 min read - 03#flybeeper #fanet-vario #fanet
The thermal leans, then it drifts: 8,409 thermals rebuilt from competition tracks
From the tracks of 28 competitions I rebuilt 8,409 thermals. Near mountain terrain the column stays put and leans at 45°; higher up and over flat land it stands nearly straight and drifts at two thirds to three quarters of the wind.
22 min read - 04#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 - 05#flybeeper #fanet #flarm
FLARM, FANET and ADS-L — where the line actually is
Why I won't ship FLARM on hardware that could technically transmit it, what the licence actually permits, why FANET's adaptive interval matters in a gaggle, why LoRa means FANET can never be the EU conspicuity standard — and why ADS-L is a better bet than it looks.
8 min read