US spy drones flies in UK airspace for the first time

[Watson-Watt]

I wonder if this UAV has appeared in anyone's ADS-B log?

http://www.bbc.co.uk/news/uk-27626879

[satcom]

Mode A/C only , monitored on UHF  on three of the flights by milscanners group members and popped up on PP Mode A/C  at 57000 feet on the last flight.
Flew  clockwise circuits around the UK .

[Watson-Watt]

Thanks for that, Satcom. Nice to know that it didn't go unnoticed!

[satcom]

Not much does....but it would have been nice to get a solid fix on it using Mode A/C
I suspect that , like the B2  , squawk transmissions are short burts rather than continual.

This week we expect a gaggle of B52s into Fairford.
It will be interesting to see if they use the same procedure , or , maintain their
Squawks for longer periods.
They won't be mode S , but A/C only , so beamfinder plus will be the only way to track them in if the weather doesn't co-operate.

[edgy]

I'm wondering, since most older transponders usually have Mode-1 and Mode-2 squawks, that some of the squawks were Mode 2. Mode 1 is/was only 32 codes (XX), so probably wouldn't be seen using current A/C detector algorithms.

I think junglejets dongle algorithm gives all mode-A/C, while most of the receivers truncate streams of the same code.

As the main beam sweeps past the target it should give quite a few replies, but my Beast for example, just outputs 1 reply.  Course you can't tell if it's a mode 2 or a mode 3/A, but you can surmise a mode C...

EDIT: Another idea for detector designers, is maybe decoding the Mode 4 3-pulse reply.  These are three pulses spaced a fixed number of microseconds apart.  I'm sure drones squawk Mode 4 :-)