Author Topic: Radar reflective gilet  (Read 2283 times)

Re: Radar reflective gilet
« Reply #25 on: September 12, 2019, 08:28:38 pm »
The only time I've got that camera to fire we were two abreast (matthew) and doing 46mph. I've subsequently been past it on my own a number of times in the 35 - 40 range and never got it to fire.
Rust never sleeps

Kim

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Re: Radar reflective gilet
« Reply #26 on: September 12, 2019, 08:30:23 pm »
When I set it off I was doing about 35.
Careful, Kim. Your sarcasm's showing...

Re: Radar reflective gilet
« Reply #27 on: September 12, 2019, 09:00:39 pm »
I've made it go off whilst doing 49mph on the Bianchi.
( I think I must've really been giving it beans).
In the early days of FNRttC.

Basil

  • Um....err......oh bugger!
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Re: Radar reflective gilet
« Reply #28 on: September 12, 2019, 09:10:05 pm »
Some years ago i heard about yoofs setting off the speed camera on the Pershore Road by swinging a paint tin round on a piece of string.
Quote from: Kim
And remember that friends who organise things on Facebook aren't proper friends anyway.

Kim

  • Timelord
Re: Radar reflective gilet
« Reply #29 on: September 12, 2019, 09:15:05 pm »
Some years ago i heard about yoofs setting off the speed camera on the Pershore Road by swinging a paint tin round on a piece of string.

I set the speed camera on the Bristol Road off by annoying an Audi driver (by existing) into flooring it past the speed camera.  Sadly it was pointing the wrong way to capture my massive grin.
Careful, Kim. Your sarcasm's showing...

Cudzoziemiec

  • Waking up now, put the kettle on!
Re: Radar reflective gilet
« Reply #30 on: September 12, 2019, 09:39:08 pm »
Some years ago i heard about yoofs setting off the speed camera on the Pershore Road by swinging a paint tin round on a piece of string.

I set the speed camera on the Bristol Road off by annoying an Audi driver (by existing) into flooring it past the speed camera.  Sadly it was pointing the wrong way to capture my massive grin.
;D
I do not ride a great big Mercian, gangster tanwalls, fixed cog in the back.

Tim Hall

  • I want to eat the fleeting shade of your lashes
Re: Radar reflective gilet
« Reply #31 on: September 12, 2019, 09:42:00 pm »
I've made it go off whilst doing 49mph on the Bianchi.
( I think I must've really been giving it beans).
In the early days of FNRttC.
Didn't Leggy and Adrian (perhaps you as well) set it off then apologise/explain to a grumpy motorcyclist that it was them, not he  that caused the flash?
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)

Re: Radar reflective gilet
« Reply #32 on: September 13, 2019, 08:25:00 am »
Matthew and I overtook a car just before setting it off. There was no subsequent conversation however.
Rust never sleeps

Re: Radar reflective gilet
« Reply #33 on: September 13, 2019, 10:10:05 am »
Would chaff work? I can see it rapidly decelerating from air resistance. I would have thought a fixed reflector would work better...
ETA: it would look super cool though...

Yay! Litter!
"Yes please" said Squirrel "biscuits are our favourite things."

Re: Radar reflective gilet
« Reply #34 on: September 13, 2019, 10:58:04 am »
Matthew and I overtook a car just before setting it off. There was no subsequent conversation however.

I am not sure we triggered the camera but we were either side of one of the large scooters. Mini Hatler was driving you down the hill at a fair lick but the camera didn't fire which was why the rider had a joke with us. If you set it off at a different time I wasn't involved.

Re: Radar reflective gilet
« Reply #35 on: September 13, 2019, 04:13:55 pm »
Would chaff work? I can see it rapidly decelerating from air resistance. I would have thought a fixed reflector would work better...
ETA: it would look super cool though...

Yay! Litter!
And that....

Kim

  • Timelord
Re: Radar reflective gilet
« Reply #36 on: September 13, 2019, 04:48:26 pm »
Would chaff work? I can see it rapidly decelerating from air resistance. I would have thought a fixed reflector would work better...
ETA: it would look super cool though...

Yay! Litter!

Said anyone working in the dark corners of a theatre where the stuff was used for a panto umpty years previously.
Careful, Kim. Your sarcasm's showing...

Tim Hall

  • I want to eat the fleeting shade of your lashes
Re: Radar reflective gilet
« Reply #37 on: September 14, 2019, 04:56:37 pm »
Reporting back. I didn't get my arse in gear to molish the previously described gilet, although I did have a space blanket in my first aid kit. This remained unused.

The route was the "proper route" taking in a speed camera in a 20mph zone in Coulsdon  a camera at the foot of Reigate Hill in a 30 mph zone and the o e just past the golf course on the descent to Brighton.

Anecdota said that no one had ever set off the Coulsdon camera, suggesting perhaps it wasn't switched on. I gave it beans anyway, but no flash.

Reigate Hill had a lot of motorised traffic, due to the southbound M23 being closed for roadworks. I waited for a suitable break and sound the bike up to R17. While the lower stretch of the hill has been resurfaced,  the initial part was as rough as a fence post,  with filling shaking corrugations. I was lined up for possible success but when I rounded the final corner there was a sea of brake lights, as I'd caught the motorised traffic. Applied the brakes and coursed my luck.

The run into Brighton was at about 0830 so again lots of motorised traffic, the drivers of which braking as the went past the camera. No flash here either.

Summary: No flashes, no one died.
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)

Re: Radar reflective gilet
« Reply #38 on: September 14, 2019, 06:44:48 pm »
I was at 39mph through the Brighton camera but wasn't aware of any flash.
Rust never sleeps

Re: Radar reflective gilet
« Reply #39 on: September 14, 2019, 09:41:08 pm »
Sadly I don't think chaff will help you. The piggy-banks appear to operate by Doppler, and thus most likely to be continuous wave rather than pulsed.

The radar cross-section of your average oik onna bike won't be much compared to the metal back end of a Q8, so don't be surprised. A bit of corrugated tin facing said camera would probably be sufficient though, and anecdotally it appears a second rider is sufficient.

Given the choice I'd go more active jamming, albeit illegal, so this is strictly a think-piece.  :demon:
Provided one can determine the base frequency of the camera, which is a box of tricks in its own right, then there are 2 things one could do.
1. False inject a ludicrously high speed into it, say 240mph. v= df/f*c/2, so 240mph difference to 10Ghz is only 16kHz. Incidentally 35mph comes out at about 2.3kHz. This is also why you can't outrun a speed camera. Compared to c, your pedestrian dawdling at anything less than Mach 3 is too easy to set a receiver for. However the Beak is unlikely to agree the camera was operating correctly when 240mph comes before him from a 10yr old Citroen. Potential drawback that if this is the 3rd time, your car might get Heavily Investigated. And this might be a bad thing.
2. Overload the base frequency, so it can't detect the higher Doppler against the noise floor. Bit harder as you have to be really precise when capturing the base frequency, and correct your apparent speed to the stationary device, and hope they're not doing FMCW, but the payback is that you don't get flashed at all.

I'd recommend against barrage jamming, simply because it's much easier to spot that Something Is Going On when SkyTv, AirWaves and who know what else get all fuzzy when that Honda CRV goes past. You also might be actually interfering with Something Important, and that wouldn't be right.
Cruzbike V2k

Re: Radar reflective gilet
« Reply #40 on: September 19, 2019, 11:08:56 am »
Sadly I don't think chaff will help you. The piggy-banks appear to operate by Doppler, and thus most likely to be continuous wave rather than pulsed.

The radar cross-section of your average oik onna bike won't be much compared to the metal back end of a Q8, so don't be surprised. A bit of corrugated tin facing said camera would probably be sufficient though, and anecdotally it appears a second rider is sufficient.

Given the choice I'd go more active jamming, albeit illegal, so this is strictly a think-piece.  :demon:
Provided one can determine the base frequency of the camera, which is a box of tricks in its own right, then there are 2 things one could do.
1. False inject a ludicrously high speed into it, say 240mph. v= df/f*c/2, so 240mph difference to 10Ghz is only 16kHz. Incidentally 35mph comes out at about 2.3kHz. This is also why you can't outrun a speed camera. Compared to c, your pedestrian dawdling at anything less than Mach 3 is too easy to set a receiver for. However the Beak is unlikely to agree the camera was operating correctly when 240mph comes before him from a 10yr old Citroen. Potential drawback that if this is the 3rd time, your car might get Heavily Investigated. And this might be a bad thing.
2. Overload the base frequency, so it can't detect the higher Doppler against the noise floor. Bit harder as you have to be really precise when capturing the base frequency, and correct your apparent speed to the stationary device, and hope they're not doing FMCW, but the payback is that you don't get flashed at all.

I'd recommend against barrage jamming, simply because it's much easier to spot that Something Is Going On when SkyTv, AirWaves and who know what else get all fuzzy when that Honda CRV goes past. You also might be actually interfering with Something Important, and that wouldn't be right.

I think you may have misinterpreted the intent of this thread, the aim here is to trigger the camera to flash whilst you cycle past at circa 35mph on a decent. Being on a bike and only being there once every three to four months the likelihood of the local constabulary tracing you to charge you with furious cycling is limited so it is primarily about the Kudos points in the peleton.

Re: Radar reflective gilet
« Reply #41 on: September 19, 2019, 04:39:15 pm »
Setting it off? The conversation had drifted away from that, but it's far easier. In fact the yoofs wiv a paint pot onna string had the right idea. A decent metal target going fast enough.

Or a corner relfector at least quarter wavelength in size. Ideally a flat metal plate is best, but its directionality is poor. Metal mudguards would help, or plastic with tin tape. Humans have a rubbish RCS, and a bike is very thin. Panniers would help, but not aerodynamically.
Cruzbike V2k