Around 7000 people all over the world have installed a small SDR (usually a Raspberry Pi with a low cost Software Defined Radio receiver) and an antenna to receive 1090 MHz and feed the data into their project. The received data is collected (ADS-B) and correlated to create MLAT positions. As they need to see an aircraft with 4 feeders to be able to find its location with MLAT the best way to expand coverage is to install your own feeder, even if there are already some in your area, or help them arrange to place one in the area of bad coverage.
ADSBexchange started as (and still is) a group of aviation enthusiasts pooling their feeder data to provide the most complete picture of air traffic possible without the censorship present on the “large, commercial networks”. ADSBx prefers to allow “free” access to as many features as possible. They don’t put features behind a “paywall”, then hold them ransom to encourage/force people to feed.
Their primary goal though is to answer the question of “what’s up there” rather than “is grandma’s flight on-time”. The photos shown on ADS-B Exchange are not provided by ADS-B Exchange, rather they are hosted and provided by planespotters.net. So there are certainly differences from FlightRadar24, but as ADS-B Exchange says, they are not trying to tell you if grandma’s plane is on time.
See https://globe.adsbexchange.com/
#technology #opensource #alternativeto #flightdata #flights