Mode S transponders transmit on 1030 Mhz. ADS-B receivers like the PIAware have only 1090Mhz receivers. How does MALT work when the receivers can not even receive the frequency that the transponders are transmitting on?
Mode S transponders don’t transmit on 1030 MHz, they transmit on 1090 MHz. 1030MHz is the uplink frequency used by ground stations to interrogate aircraft.
3 Likes
The Air Traffic Control Radar Beacon System (ATCRBS) and the
Mode Select (Mode S) system have a ground-based and airborne component and operate
on the frequencies of 1030 MHz and 1090 MHz.
https://www.ntia.doc.gov/files/ntia/publications/compendium/0960.00-1164.00_01MAR14.pdf
The interrogation y ATC radar is done on 1030 MHz, the transponder then responds on 1090 MHz.
1 Like
Thank you. (need to have 20 characters.)
1 Like
You can click on the little heart under his post.
1 Like
MLAT is similar to how GNSS/GPS works.Both use trilateralisation
You have several known ground location. Each ground location gets timing information from specific ADS-B signals. The MLAT servers use this timing information to work out the location of aircraft that are not transmitting position information.
With MLAT the receiving locations are known. With GNSS/GPS the satellite locations are known. GNSS/GPS use much larger distances, however, the clocks are better.
Here are a couple of more detailed articles:-
Write [spoiler]abcd[/spoiler] (it is more than 20 characters) and post.
It will appear as abcd
To see the spoiled characters, click on the smudge.
Alternatively you can write [spoiler][/spoiler] (19 characters) and it will show nothing, and fulfil 20 char requirement even if your message is only one or two characters like no or 1 etc.
2 Likes