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GATSOS OVER-READ YOUR SPEED!! Yeee Haaa

Discussion in 'General Chat' started by C_Audiboy, Jan 10, 2005.

  1. C_Audiboy
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    C_Audiboy Vroom Vroom

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    All,

    Check this out: Piston Heads

    It looks like the rozzers number is up at last.

    Instead of making the cheques payable to the Chief Constable, they'll be sending the cash back to us /ubbthreads/images/graemlins/laugh.gif

    Court case is heard on Thurs 13 Jan, and it appears there is strong evidence that the Gatso system has something fundamentally at fault, with something like 80% of cameras tested showing speeds 25% quicker. I'll be watching this one closely!!
    #1
  2. phil1978
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    phil1978 Member

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    Hope he wins, that'll definately open a can of worms for the police force and their admin. He he.
    #2
  3. NEiLS3LK51
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    NEiLS3LK51 Member

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    Do they actually use a fixed 500ms for T in the velocity calculation or use an in-gatso timing measurement which can vary as long as its known?

    (V = D/T) This will not affect the V result as a bigger T will give rise to a bigger D as argued but will result in the same V, right??

    Course we're being screw'd if they fixed at 500ms!
    #3
  4. ajmackie
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    ajmackie Member

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    Yeah velocity will remain constant based upon higher distance and highter time, but like you say, all they'll do is work off the standard 0.5 seconds.

    i heard another interesting thing. the camera is offset on the side of the road and so uses trigonometry to calculate the distance for the radar. so what's to say that the camera hasn't been knocked by summit?

    i want to know what triggers the camera. if it is emitting a constant beem of radar then the car reflects it back, how come standing in front of it doesn't reflect it, thus thinking there is a car there.
    does it emit the radar in pulses and then if it is no longer there after a fixed time it must be speeding so takes the pic.
    must be a way of triggering them off falsely!
    #4
  5. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    It's constantly emmitting (that's why radar detectors can pick them up). When a car is in range it can tell by the speed of the deflected (reflected?) signal whether the car is over the set threshold, then takes 2 photo's which can then be used as evidence against the lines in the road.

    Truvelo camera's (the front facing ones) do not emit any signal so can't be detected (only identified by GPS systems). They use 3 lines in the road (with sub surface piezo sensors buried in the tarmac) to measure speed & then use an infrared flash to take one photo (of car & driver) without blinding you. The trigger is very close to the camera (you can see the 3 lines in the road only feet in front of the camera) and the picture taken very close up (just before you pass the device) so it does get a very good pic of the driver.
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  6. ajmackie
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    ajmackie Member

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    i wonder whether it is illegal to drive round with a paper bag over your head like when clarkson drives the lada!!! /ubbthreads/images/graemlins/lol.gif hmmmm
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  7. CJ A4
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    CJ A4 Active Member

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    Yeah but haven't they highered the limit on alot of the cameras to between 5 and 10 mph hour above speed limit to stop this from happening?
    #7
  8. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    Maybe on Gatso's, but there's a Truvelo camera up the road from me on a dual carriageway (30mph) and it went off at the car in front of me which could only have been doing 35mph, as I was at 33mph (according to RA) and he was marginally faster. Definately no way an accident blackspot as I've lived in Southampton for 14 years and never so much as seen a rear end shunt on this stretch of road.
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  9. NEiLS3LK51
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    NEiLS3LK51 Member

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    The radar signal reflected and recieved by the gatso only triggers if there is a positive doppler shift of a certain threshold of the original frequency.
    Meaning the car is moving too quickly towards it for its liking.

    I can't believe they could possibly claim any accuracy due to component tolerances and differing temperatures for the 500ms. Not the way I'd do it.

    Perhaps I should ask Gatsometer for a job, that'd make me popular!
    #9
  10. CJ A4
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    CJ A4 Active Member

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    Well it's a fact and everyone knows that these are money making schemes and have been put in the most unlikeky blackspot areas. They will argue differently but the figures speak for themselves. 100's of millions every year in fines and the revenue from drivers without fines or anything just normal costs...road tax, petrol is 36 Billion of which 6 Billion is allocated back into the roads for improvement. I for one am totally fed up being used as a source revenue for other government plans just because i drive!
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  11. ajmackie
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    ajmackie Member

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    I take it positive is when it is moving away from the camera? so if doppler can shift colour or sound (e.g. ambulance siren), does that mean it is compressing or elongating the wave length. So basically the radar comes back at a different frequency. So depending on what frequency it is at, it knows whether you're speeding.
    Have i got that correct?!

    why can't everyone just not speed. don't people realise that speeding is making them put more cameras up!
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  12. CJ A4
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    CJ A4 Active Member

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    No they just use speeding as an excuse! If the government is so proactive in saving lives then why dont they ban cigarettes and alcohol two of the biggest killers in this country! It's just another revenue making scheme that looks good for PR!
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  13. ajmackie
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    ajmackie Member

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    oh i agress 100% CJ, all i'm saying is that if everyone stopped speeding, then it wouldn't be viable to put more cameras in or maintain as many as they wouldn't be making anything out of them and they'd just be a cost.
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  14. NEiLS3LK51
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    NEiLS3LK51 Member

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    Positive is moving towards the camera the wavelengths are compressed hence frequency is increased, like the high pitch noise formula 1 engines generate as they get close. Then get lower as they pass, elongating.

    If the received frequency gets to high for the gatso it triggers.
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  15. ajmackie
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    ajmackie Member

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    so in that case ... you could build a radar emitting device and trigger them off and waste all of the film .... hehehehehe hmmmmmmmm!

    wonder whether the radar is coded so that you can't do this
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  16. jdp1962
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    jdp1962 Grumpy Old Moderator Staff Member Moderator

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    I believe Gatso cameras are fundamentally unlawful, because they do not apply the law equally. They are programmed to "trigger" when a vehicle passes at a speed that is greater than a pre-determined threshold. That threshold is generally set at the prevailing speed limit, plus a margin of whatever percentage. However, what is the "prevailing speed limit" that the partnerships use when setting the threshold? Invariably, it is the designated speed limit for private cars, i.e. 70mph on a motorway or dual carriageway. The problem is that the speed limit on the same road is much lower for other types of vehicle, such as vans, trucks or cars towing caravans. The camera has no means of detecting the type of vehicle that is passing it.

    So, let's say the speed limit is 70mph, and the threshold has been set at 82mph. If I pass that camera at 84mph, the camera will trigger. I am exceeding the speed limit by 20%. Suppose a car & caravan combination passes the same spot at 80mph. The driver exceeding the speed limit by 33%, because the speed limit for that vehicle is 60mph, yet the camera won't trigger because his speed is below the threshold.

    Thus, GATSOs actually operate in such a way that fails to catch drivers who exceed their speed limits by a greater proportion.


    /ubbthreads/images/graemlins/burningmad.gif /ubbthreads/images/graemlins/burningmad.gif /ubbthreads/images/graemlins/burningmad.gif
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  17. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    and also Truvelo camera's fail to catch motorbikes the biggest death statistic on our roads.
    So the safety angle is shot to pieces.
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  18. ajmackie
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    ajmackie Member

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    as if the government cares about all of this though!
    never thought about it like that jdp, well thought! I agree!
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  19. CJ A4
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    CJ A4 Active Member

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    I think the root of the problem with speed is that people don't know how to control a car going fast. Go back to the drawing board and make the driving test alot harder and alot more indepth, skid control, braking and evasive manouvres in the wet, these are fundamental issues which we potentially deal with everyday on the roads. Awareness and knowledge=safer driving!
    #19
  20. ajmackie
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    ajmackie Member

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    yeah but then they won't have as many people passing which means no road related taxes for them!
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  21. CJ A4
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    CJ A4 Active Member

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    Yeah suppose they will only get it another way. But less people on the road is that such a bad thing...Too many cars on roads now as it is ajmackie. Just look at any city or towns during rush hours noone escapes unless you live and work in the country! Its a nightmare and not getting any worse. Just think better drivers on the road will also mean less accidents too, which means less insurance premiums and better for us all.
    #21
  22. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    Wise words, but it's a catch 22, just like smoking.
    If everyone gave up smoking the NHS would be bankrupt overnight. Over their (limited) lifetime each "20 a day" smoker contributes 900 times the cost of treating a cancer/heart disease patient (i.e. them), so effectively the whole of the NHS is mainly funded by smokers. Thanks guys, keep lighting them up.
    That's why they won't ever ban cigarettes
    The situation is identical on the roads. Given that only a small per centage of fuel duty & road tax is actually invested in our roads (or even on any form of transport), the gov't can't afford to reduce the number of car users.
    The saving made in road upkeep/accidents etc would be minimal.
    And also there's no alternative with the trains at full stretch already and buses just being useless.
    Very very ironic when you consider all the anti smoker/anti car propaganda they're spewing out.
    #22

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