Odd Mode-C traffic

[Paul_Sengupta]

I'm south of Woking

I'm north of Guildford. If we turn our units on in our attics, we should be able to see each other. 

[Vic]

Radar Site Monitors are located close to a ground radar's antenna and are integral to the radars own internal monitoring. They are set up to simulate a specific target and have inbuilt responding delays to appear as a stationary SSR target close to the edge of the radar heads usable range. They usually squawk Mode A 7777 and Mode C of over 70,000ft.

Their appearance to the radar is internally monitored and they have executive functions to switch off the radar if errors are identified.

http://www.radartutorial.eu/17.bauteile/bt16.en.html

[exfirepro]

Thanks Vic,

Much better than my 'off the cuff' explanation. I have a screen grab from early Mode S  testing back in January showing two local ones squawking 7776 and 7777 concurrently, both showing a (relative) altitude of 61,075ft. At the time I couldn't figure out what they were. Now we know.

Regards

Peter

[Admin]

Hi Vic,

So that very high altitude mode C would have been these possible squawks

62000     0    0    0    0    0    1    0    1    0    0    0    1    0424
62100     0    0    0    0    0    1    1    1    0    0    0    1    0434
62200     0    0    0    0    0    1    1    0    0    0    0    1    0414
62300     0    0    0    0    0    0    1    0    0    0    0    1    0014
62400     0    0    0    0    0    0    1    1    0    0    0    1    0034
62500     0    0    0    0    0    0    0    1    0    0    0    1    0024
62600     0    0    0    0    0    0    0    1    1    0    0    1    0064
62700     0    0    0    0    0    0    0    0    1    0    0    1    0044
62800     0    0    0    0    0    0    0    0    1    0    1    1    0046
62900     0    0    0    0    0    0    0    1    1    0    1    1    0066
63000     0    0    0    0    0    0    0    1    0    0    1    1    0026

are these Mode-A squawks that potentially get allocated ?
This is kind of academic, because these Mode-C Alts are not going to be considered
when a reasonable Mode C/S Separation is selected, eg +/-2000ft

[Vic]

Lee

Under ICAO DOC 4444 the only internationally reserved squawk codes are 7500 7600 and 7700.  State governments then deal with allocation of all the other codes.

Found this which might be helpful

http://www.flightradars.eu/squawkcodes.html