Strange Transponder showing up

[SkynetCentral]

Hello All,

Wonder if anyone here can shed some light on a rather off Transponder I’m detecting on my system under MLAT

Just today my systems been showing up a transponder as follows;
Hex: 43BF7E
Reg.: n/a
United Kingdom
Type: n/a
Type Desc.: n/a
Squawk: 7777

SPATIAL
Speed:82 mph
Altitude:62,000 ft
Vert. Rate: -192 ft/min
Track: 119.4°
Pos.: 55.917°, -3.156°
Distance: 32.0 mi

SIGNAL
Source: MLAT
RSSI: -11.7
Msg. Rate: 10.0
Messages: 251109
Last Pos.: 3.8 s
Last Seen: 0.2 s

It’s showing on the map as South East of Edinburgh Airport over Loanhead / Dalkeith

Obviously it’s not a real aircraft (the Map Plot of the MLAT kinda proves that, well unless it’s the TARDIS lol)

Also the Squawk of 7777 and Altitude holding at 62000ft kinda made that obvious.

However… I’m stumped as to what it is or why it’s even broadcasting!??

Can anyone give a newcomer a spot of education. Please

Thanks

[Coooogz]

A quick google on that HEX code and “adsb” will give you multiple hits.

From that search… Squawk 7777 =
Non-discrete code used by fixed test transponders (RABMs) to check correctness of radar stations (BITE) (Belgium, Germany, Netherlands, USA)
DOD interceptor aircraft on active air defense missions and operating without ATC clearance in accordance with FAA Order 7610.4 (USA)[15][23]

[ScotsSharer]

It is a calibration transponder, it will be on a local tower. Used by them to calibrate the WAN MLAT system the airport uses. The usually have them reporting at ridiculous heights or even at underground negative figures so they don’t get mistaken for anything.