New type of speed camera...

[PaulyJ]

Wonder if this will come into play

http://www.leftlanenews.com/2006/04/27/new-speed-traps-could-measure-speed-based-on-sound/

[oneightoo]

hmmm interesting..

would be keen to know how it works out the speed tho.. what if your flying down in a 60 zone doing 210kmph, and your sitting in neutral?

[PaulyJ]

thats exactly what i was thinking before
fly past, car in neutral, easy

[oneightoo]

all you would need is a list of where the cameras are located, which isnt hard to get.. approach the camera, slide into neutral, bang straight thru, and the camera is none the wiser..

[tmov81]

load of $hit... wont ever happen... it wouldnt ever work, and even if it did, why f$%king bother... lidar/radar is so much more cheaper and effective...

there is no way they could effectively isolate a single car automatically, and then determine whether the doppler effect from the exhaust note is the result of the car moving away quickly or the driver downshifting, etc etc...

what a pointless waste of money researching such a useless idea... the speed cameras are unreliable as is... and they are trying to introduce something even more unreliable... stupid people...

[oneightoo]

only in america

[Clint]

and what if u drive by with the sub making more sound that the actual car makes?? the sound from thew sub isnt consistent but some would be louder than the car

[EL BURITO]

that is just silly cos of the amout of varriables.

[180HOA]

load of $hit... wont ever happen... it wouldnt ever work, and even if it did, why f$%king bother... lidar/radar is so much more cheaper and effective...

there is no way they could effectively isolate a single car automatically, and then determine whether the doppler effect from the exhaust note is the result of the car moving away quickly or the driver downshifting, etc etc...

what a pointless waste of money researching such a useless idea... the speed cameras are unreliable as is... and they are trying to introduce something even more unreliable... stupid people...

Are you a scientist?

I only ask because I think you'd need to be to make that call... I'm not a scientist myself, so I can't think of a reason why sound-based speed-detection is any less legitimate than radar.

Perhaps the two could be used together to improve the reliability of the readings they provide?

[PaulyJ]

Its just another way of using a sonar type radar, like in submarines.
They're based on sound.
I think it could be possible.
Anything is possible with the right amount of money thrown at it.

[tmov81]

Are you a scientist?

I only ask because I think you'd need to be to make that call... I'm not a scientist myself, so I can't think of a reason why sound-based speed-detection is any less legitimate than radar.

Perhaps the two could be used together to improve the reliability of the readings they provide?

yes i am...

I am currently doing my Ph.D. in the measurement reliability and validity of
piezo-electric transducers where low level force/moments are registered and the extent to which trial protocol, sample rate, filtering protocol and environmental noise cause the recorded signal to vary from the actual performance...

i hope that answers your question :)

radar/lidar is shooting multiple pulses at a vehicle and calculating the variation in time for the pulse to bounce back. yes it can be inaccurate, but that is mostly down to if the operator does not use it properly.

attempting to pick up the tone/pitch of the exhaust note is a waste of time. it probably could be done, but it will always be less effective than radar/lidar, and it will be subjected to so many more extraneous variables. You cannot simply filter out the exhaust note of other vehicles. for example two stock 1.8L astras cruising side by side. the exhaust note will be fairly similar frequency/amplitude. how do you isolate the exhaust note from one vehicle? more importantly how do you set it up to be automatically operated?
what happens if you have a motorbike coming in the opposite direction... it will sound like you are hammering it as you move away from the sensors... there are just too many uncontrollable factors.

attempting to identify changes in the exhaust note as it drives away is a lot more complicated than shooting a laser beam at the car. it could possibly work, but it is a waste of time... i mean if anyone can come up with suggestions as to where radar/lidar could not be used but sound based analysis could be used... but i for the life of me cannot think of any reason why people would waste time and money doing this other than so they can say they can... i mean its like saying i drove from melbourne to sydney via adelaide... yeah you might be the first person to do it... but who cares... you can drive directly from melb to syd and it is quicker, cheaper and makes your trip less prone to problems.

[pred8r]

I will say yes it would work, but the accuracy could be questionable.
I live on a long straight and someomes late at night ive heard cars(?) go past QUICK (100kmh+ easy) and all you hear is the tyres on the road.

if they measured the sound at say 1m apart then they will know how fast you are going. Given distance and time taken would give them your speed exactly.

The Amphometers were one of the most accurate way of catching speeders, except you could see the straps.
They use something similar on the western ring rd in melbourne (uses 2 cameras and in-ground straps to do it).