Never seen ADS-R before,first time today I seen it.

What is it? Just wondering.

A quick google search reveals ADS-B vs ADS-R | Difference between ADS-B and ADS-R

I’m located in Australia and I don’t believe it is used here.


In the US, 978MHz UAT ADS-B retransmitted on 1090MHz (or vice versa) by ground stations, so that aircraft equipped with only 978-in or only 1090-in are aware of aircraft transmitting only on the other frequency.

Basically a workaround for the US deciding to use two separate ADS-B systems on different frequencies.


If 978 MHz UAT is rebroadcast on 1090 MHz, then that would seem to mitigate the reason for even having 978 MHz UAT – ie to reduce the number of users and interference on 1090 MHz. But maybe I’m not understanding it correctly.

Thank you for that info.

UAT 978 was originally supposed to be cheaper than 1090. It also includes weather and FIS-B, which are not available using 1090.
1090 is busy in many areas. I can see 6000 packets per second if I enable Mode C on my radarcape in NYC.

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