Laser Speed Sensors nr M5 J4A?

[mdb55]

Hi all. So I have a gps/radar/laser detector thingy fittted, it's more of a gadget than a useful device tbh. The laser detector rarely activates, which isn't at all surprising.

However I've noticed that on the section of the M5 south of J4a (M42) both northbound and southbound I tend to get a positive laser hit most of the times I traverse that stretch. It'll hit quite often in this area, not each time and not in exactly the same stretch of road each time.

Has anyone else noted this, and/or know what the source is? I'm 99% sure these are not from a camera van (if they are, it is always very well hidden). I know this area is covered by HADECS3 cameras but I thought these were radar nor laser, and unless these are reflections, it wouldn't quite explain the slightly random activation point each time?

And for those of you who might suggest I drive at bonkers speeds to see if it really is a camera/laser speed detector then err thanks but no thanks :-)

[Whataguy]

Years ago I had a detector, for some reason it sometimes gave laser alerts at the barrier in car parks.

Perhaps it's something to do with CCTV/ANPR illuminators being on the same wavelength as lasers for speed measuring. They probably have them on the section of motorway.

I didn't have it long, self-opening doors at petrol stations/etc also set it off too.

[Bright Halo]

There are cameras on the gantries (not all but some) down that stretch, not sure if the use lasers to detect speed though?

[mdb55]

Thanks guys, I definitely know there are HADECS3 cameras in that stretch but I thought they were K-Band radar based and not laser. The ANPR theory is interesting, I have had a laser hit going into a retail park car park area and thinking back I know it uses ANPR to log time in and out.

[Boosted LS1]

If behind an ambulance or fire engine laser devices will ping a lot. I imagine it's because those vehicles are sending out laser signals all the time for reversing. Some traffic lights or a low sun, HD headlights etc all cause a reaction and that'e even before the scamerati start chucking out beams. Better off without a front plate.

[mdb55]

I'm pretty sure most of the reversing sensors, vehicle mounted lane/stopping distance sensors, fixed speed detectors and even temporary traffic lights use K-Band radar and not lasers.

Given that it pings a laser hit on this same stretch of the M5, and doesn't do that almost anywhere else on 100s of miles of motorway (including near other HADECS3 sites), then I can only assume its something else/quite unique here.

[Zephyr Speedshop]

many moons ago, a customer of mine used to have a laser/radar scanner in his van. it used to go off when going past shops with the automatic opening doors.

I was supprised at the range it would be set off by them at the right angle it would be 50-60 meters away. pehaps theres a building ajasent to the motorway thats causing it?

[mdb55]

Thanks, yes those automatic door sensors are radar based and operate in the Ka band. They have a surprisingly long range.

Looking at Google maps, I'm increasingly of the opinion this might be caused by the IR spotlights attached to the CCTV cameras on this stretch of the M5. Theyre unusually mounted on super tall poles in this section, so I assume the spotlights have to operate at à very high LUX to be effective. Coupled with the incline of the road, it may be the IR spotlight is almost pointing straight at the laser sensor as if it's on the line of sight horizon. Some further investigation required.

I do know LED headlights can be a cause of false positives on other laser detectors, but it'd be going off all the time then and mine alerts on this M5 stretch during daytime too (and thankfully I havent encountered anyone driving straight at me the wrong way....yet).