seriewoordenaar

Anything that flies with a working Mode S transponder will be visible. At the end of March I spotted the Marine One helicopter with POTUS on board near Brussels, even though they'd obfuscated the ICAO aircraft address. A fleet of police and army helicopters were also on duty that day according to the Plane Plotter log. What you won't see is their position on the map - they don't reveal their position nor speed, just ID and altitude.

You probably meant 143.050 MHz - the GRAVES radar in France? Depending on where you are in the UK, you might try to pick up two radio beacons specifically dedicated to meteor scatter in Belgium : The 150 Watt beacon at Dourbes (Centre de Physique du Globe, GPS coordinates 50° 5' 51.1" north, 4° 35' 18.5" east) transmitting on 49.97 MHz CW and RHCP. The 50 Watt beacon OT1KZG at Zillebeke (Astrolab IRIS - Vereniging Voor Sterrenkunde, GPS coordinates 50° 49' 3" north, 2° 54' 45" east) on 49.99 MHz CW and LHCP. There's a network of about two dozen stations - Belgian RAdio Meteor Stations - gathering meteor data from the Dourbes beacon. Each month they send this data for processing to the Belgian Institute for Space Aeronomy in Uccle. I put a SHOUTcast DNAS on one of these BRAMS stations so people worldwide can listen in 24/24 : http://81.82.192.207:8888/stream/1/ Paste the URL into a media player - NOT into your browser - VLC, Winamp, ... all work fine, to listen. You'll hear two channels : left the actual radio feed from Dourbes, right the Pulse Per Second NMEA data stream from an attached GPS used for precise signal timings. The best way to enjoy it is to listen AND watch the spectrogram generated by the freeware Spectrum Laboratory software slide by. Due to its poor dynamic range, I doubt that a cheap RTL-SDR dongle might pick up these signals, but I'm always curious if it actually works! As a side project I'm using an RTL-SDR dongle to capture ADS-B data from aircraft passing near the Dourbes beacon to identify their Doppler signatures - and this works! A sound file captured from the Dourbes beacon September 3, 2011 where you can hear two very clear overdense meteors in a row : https://dl.dropboxusercontent.com/u/52458256/2011-09-03.wav With this you have an idea of what to expect!

Only about 60-65 % of the aircraft detected by ADS-B reveal their position. The ones that don't are military and private aircraft - business jets, small single-engined turboprops, and old aircraft lacking a GPS belonging to dubious airline companies. You probably came across the term 'MLAT' or 'multilateration' - a triangulation technique that can reveal the position of these aircraft. It requires a special setup (precise timing) of the ADS-B decoder software and a community of MLAT sharers. It might be a good idea to devote an HAK5 episode to this subject? Late March POTUS and his flying circus were in Brussels, Belgium. Obviously none of the aircraft revealed their position, only the ICAO hex address, callsign, and altitude. POTUS took into the air with a fleet of two US Marine Corps Sikorsky VH-3D Sea King (one of which was 'Marine One') and five US Army Sikorsky UH-60A Blackhawk helicopters (to visit the only American military cemetery in the country). The five Blackhawks revealed themselves on ADS-B Mode S, but the two US Marine choppers went a step further - one was invisible altogether, and in the second one its ICAO hex address had been changed to the non-existing '000001', but they forgot to suppress the altitude, hovering around 1,000 feet, revealing that it belonged to an helicopter. MLAT could unsneak the sneakers! I used PlanePlotter/RTL1090 and an RTL2832U/R820T dongle with the original antenna to track their movements. HAK5 fan from Belgium.