Airfield Radar and car cruise-control radar

[nacluv]

Hello to all.

I haven't a clue which forum is best for this question, so here goes.

A member of a car-based forum I subscribe to posed a question and I thought you guys may have some insight which could help out.

The bloke's problem is that he has a car which is equipped with Radar-controlled cruise control. It stops working if he drives past any airports. His car dealer has told him that the problem is caused by the airfield radar interfering with the car's radar.

This poses several questions, the first being - is this complete B.S? If not, then how can car manufacturers pick the same bandwidth of radar as airports for their particular application? Is there any possibility of the interference going the other way - i.e. a passing car interfering with an airliner's approach to a fog-bound airport?

Any clues would be welcome!

[HEATHROW DIRECTOR]

Firstly, do car cruise controls really use radar? Seems a bit OTT to me. I suggest that the term "radar", which means radio detection and ranging, might have been used by a car salesman trying to sound clever! However, I suppose it really might have some sort of radar to measure distance to the car ahead....?

Secondly, it's not a case of car companies using the same frequencies as airport radar but more a case of cheapo car electrics being overloaded by a very powerful radar transmission. Aviation radars can be on any one of a number of frequency bands but domestic TV and radio, etc., can still be effected by "overload" by the big signal. My car radio used to bleep as I passed the radar as the end of the tunnel at Heathrow and I was usually listening to Radio 5, the frequency of which was eons away from that of the radar. You might experience a similar problem if you are using a small radio and a police car stops outside your house as their transmitter will almost certainly block out any broadcast station you may be listening to.

Lastly, it is not unheard of for aviation radio aids to be interfered with but I don't think it would be a good idea to discuss that in public.

[PaperTiger]

The Autonomous Cruise Control radars use the W-band at 77gHZ. This overlaps the NATO M-band (60-100gHZ), so I can see the potential for interference at military airfields. You'd think somebody would have thought of this though.

[staplefordheli]

Yes, as posted previous adaptive cruise does have radar and uses the new automobile experimental 75-110 gig range band and will also be used on new guidance systems for cars and buses in the future.
AC Works a bit like normal cruise except it senses the speed of traffic in front so that it can set a new setpoint for the speed rather than relying on the driver to react and reset the cruise.
Sounds more like the electronics are being swamped by RF from one of outer marker beams although 2ghz microwave beams are pretty effective as well

They spend a lot of time now with new cars in RF chambers but they cannot get every scenario which is why a lot of car immobilisers are being inhibited by mobile phone masts built into garage forecourts, and why the AA and RAC know these hot spots and just move the car 200 m away to start it.
I once had a Pug 405 which had windows and door locks that would activate with a 25w 27mhs PMR on TX.
No other vehicle it was intalled in suffered from it although rumours persist that mobile phone kits have set off airbags on certain BMWs :eek:
Hope this helps

[nacluv]

The car does indeed use 77GHz radar.

I am just surprised that the two applications ended up on overlapping bands! How was that allowed to happen?

Incidentally, the problem happens to the car in question around Cambridge and Manchester - civil! - airports.

Thanks to all for your input.

[HEATHROW DIRECTOR]

<<Sounds more like the electronics are being swamped by RF from one of outer marker >>

ILS markers were largely withdrawn from use many years ago and they transmitted low power on 75mHz so should not have interfered. They were some distance from airports too - especially the outer marker, which was about 4 miles away.

[HEATHROW DIRECTOR]

Mig15. Correct, although the signal may be received weakly at ground a little way away from the transmitter.

[ben177]

Slightly off topic but several years ago the cars on Blackpool Pleasure Beach's new roller coaster would freeze at the top of the first incline at random intervals. The cars were controlled by micro processors, which were found to have fried. After a lot of head scratching the airport radar (which is quite close by) was blamed. If the car was caught in the sweep the electronics died and caused the brakes to apply. Putting metal boxes around the controllers solved the problem.

db

[staplefordheli]

Ah takes me back to the computer club at RAF North Luffenham in the late 70s
Not the brighetst place to test sensitive home built kit with midland radar nextdoor!!
Many hours work could be lost with one sweep of the beam

[P6 Driver]

I seem to recall reading items from conspiracy theorists about electronic emissions from a UK government vehicle convoy travelling in the undershoot of a runway interfering with the electronics of the B777 that crash landed at Heathrow some months ago. The AAIB reports suggest other causes, however.

P6D

[HEATHROW DIRECTOR]

I'm a radio amateur and could tell funny stories all day long about the weird effects radio can produce - at quite low power too. One of the better ones involved a ham who had aged aunt staying with him.. He switched on a fairly low power very high frequency transmitter and the lady leapt out of her chair. Her hearing aid was actually omitting smoke!!

Thanks for the gen on car radar - interesting stuff.

[lastgasp]

I think this is a long-standing issue. Back in the days I was into motorcycle racing I can recall that teams encountered mysterious performance problems with previously perfectly set-up engines whenever they went to Donnington Park. Penny finally dropped - East Midlands airport was just over the ridge and emissions were interfering with the engine management.

[Guest 112233]

Is there any truth whatsoever in tales of metal coiled pots flying off shelves as tornadoes thundered through Snowdonia. Lenz's law and terrain radar. F111's seemed to be culprits too - not virbrations. It happened near LLanbeder from memory - PS an actual - Where I live, the WX radars scans from the larger types on take off, are discernable as an occilating hiss on broadcast VHF - not always in every case, but often enough to be noticeable.

CAT III

And I won't go on about electric ovens near Daventry on Northants' acting as receivers.

[HEATHROW DIRECTOR]

Ham friend of mine was "received" on next door's toaster.. and on the Isle of Man the new church "bells", which were electronic, broadcast an amateur conversation far and wide on Sunday morning...

[Noah Zark.]

I wish I could get a television that interfered with my next door neighbour's electric drill! :)