https://www.youtube.com/watch?v=SH4IIPK7n0k

Is this a proven method to check active Gatsos? Would any frequency counter do or would I need a particular piece of kit?

You would just need a detector on the relevant frequency.

No signal would mean no radar installed, however a signal doesn’t tell you if it’s a ‘real’ or a dummy system.

Even if you get a signal, that doesn't mean it's active.

On the main road near me We have 3 cameras (2 northbound 1 southbound) all within 0.2 miles on a road just 0.3mls long. Only one camera is deployed and repositioned among the 3 cases and at random times. The cases appear to be completely empty with no lens or flash visible in 2 of them.

@rookie ... Surely there would be no point in fitting working expensive radar if no camera is active!

Depends, are they all digital now or do some still have the old fashioned film that someone has to come and collect?

They're not expensive at all - you can get a decent K-band speed measuring module for a couple of hundred quid.

Well ignoring the fact that the dummy units use a much cheaper radar (which triggers a flash to ‘scare’ people), much like are used in the illuminated warning signs, they do exist and are used, so whether there is no point or not is mute.