Radar

[pacmania_2001]

Who here knows a bit about radar as in that used by the police to catch speeders?

I'm thinking Cap might know a bit? If anyone does can they PM me, I am thinking about taking a speeding fine to court on the basis of incorrect setup of the radar and was looking for some technical info on radar.

Cheers.

[thecoalman]

I know that it's highly accurate..... They have these mobile radar units that they park near the side of the road that gives your speed, supposed to slow people down. It's always right on.

I'm pretty sure the only argument you can give that I have heard of working is if you were in a area with large trucks, the radar will pick up the truck before it will pick up you.

[rkr1958]

Unless you're looking at a reckless driving speeding charge or the current charge will result in your license being suspended (too many points) then I recommend that you just pay the fine. In general, judges are very reluncant to rule against their police officers. If on the other hand you really need to fight this (e.g., for reason(s) stated above) I'd suggest getting a lawyer or at least talking to one. Anyway ... this is just my opinion ... Good Luck

[Cobra]

I heard about a guy who was speedtrapped by the police in the UK. They clocked him doing 124mph in a nackered old Ford Fiesta. He took them to court, and had the car taken out on a test track by a professional driver. He got 101mph out of it, and there is no way anyone could squeeze any more.

Needless to say, the police lost the case.

[JohnnyCNote]

The radar has to be calibrated correctly, if memory serves. There are some speed trap websites that might help....

[ViRaL1]

How much 'over' were you, and was there anyone else driving near you?

[Capmaster]

Who here knows a bit about radar as in that used by the police to catch speeders?

I'm thinking Cap might know a bit? If anyone does can they PM me, I am thinking about taking a speeding fine to court on the basis of incorrect setup of the radar and was looking for some technical info on radar.

Cheers.

It's a doppler radar, many units are pulsed doppler.

The same thing that makes a train higher in pitch approaching you and lower leaving works with radio waves too.

Here's the simplified explanation:

The radar is calibrated with a baseline for 0 MPH. The IF (intermediate Freq) stage outputs a signal proportional to the shift from that baseline. The higher the speed, the greater the shift.

As the car approaches, the radar gun measures the shift by sending out pulses of RF, down-converts the frequency, passes it through a bandpass filter to ignore spurious signals, and using a DSP (dig. signal proc.) circuit, converts the IF to MPH based on that cal. baseline. Many units only require that the gun be pointed at a stationary object to calibrate the unit.

They are highly accurate ....when pointed at a moving object that has no other vehicles close. If a truck or other vehicle is next to it, and its antenna isn't perfectly directional with a sharp dropoff and minimal side-lobes on the antenna pattern, scatter could fool the unit into receiving the return signal from the other vehicle.

To successfully argue the case in this manner, I think you need to find out the specific unit used, then get the specs for it, translated into a "window of effectiveness" so the judge and maybe jury can understand. Argue that without a very steady hand the reported speed is questionable. After all, human error is a big variable any time a radar gun is used.

As far as the unit itself, excluding human error, it's extremely accurate and very difficult to dispute. But adding the aiming error question might give you something. Just remember that if you go that route, it ends up being his word against yours, and people rarely win those in court on speeding tickets.

[ViRaL1]

You could be lucky and the officer may not show up. Then you win by default.

[smearbrick1]

Straight from the mouth of PA State Trooper (friend of mine):

You will very rarely ever win a hearing when you are claiming faulty equipment. The best thing you can do is, request a hearing. Before the hearing (same day) find the State Trooper, policeman, policewoman, etc... who issued you the citation and ask them if you can plead guilty to a lesser charge.

John (that's the trooper's name) said that he will normally knock the charge down to 5mph over which is a no points offense.

I learned all of this recently when I got pulled over at 75 in a 55. The cop accused me of trying to evade... never charged me with it (I wasn't trying to evade.) I went to John to ask him if I could get out of it and he basically said I was screwed. I could of used the hearing recourse I mentioned above but I had already spoken with the Trooper's supervisor and basically told him that his Trooper was piece of shit.

[makntraks]

You could be lucky and the officer may not show up. Then you win by default.

Your best shot is right there.....

makntraks

[redwudz]

At least in California, in a city, a speed study has to be done on the street the citation was issued. Locally they base the legal speed on the '85th percentile'; a way of finding the average speed.

If most everyone is driving 30MPH on a street posted at 25MPH, they can't ticket you for speeding at 30MPH. You can sometimes dispute the results if the study hasn't been conducted. However, they usually only radar streets that have been studied. On the state highways, CHP usually gives you 5MPH to 7MPH over as a 'speedometer error'.

I doubt you can dispute the results of a radar unless you were only a mile or two over the legal limit, or can show that the unit was used or calibrated improperly, which rarely happens. Good luck.

[yoda313]

Hello,

On the state highways, CHP

Ah.... The famous CHIPS!

Kevin

[BJ_M]

they use a pitchfork to calibrate them around here , you really can't dispute that ...

get some stealth bomber paint ..... or a nice reflective fan exposed in front of the rad ...


laser is used now a lot instead anyway ...

[CoasterCreator]

I heard that some people fight that the equipment was not properly maintained ..I think they have to check their equipment every so often..anyhow that is what I heard once , hopefully the officer wont even show..

call the police station around the court hearing time and say that your the electric co. and the officer needs to come home to disconnect all his electrical equipment do to some power lines gone down

[BobV]

I'm not going to be a lot of help but I know a book was written on the subject. I remember the author saying almost every speeding ticket can be beaten.

[redwudz]

I rode with a CHP officer for a few hours a while back as part of my job. (Yes, I was in the front seat with no cuffs!) He showed me their RADAR setup. Impressive. It can select forward, back, right of left. Works whether the vehicle being RADARed is coming or going away. A large truck shadowing the vehicle will cause a misreading, but trucks are usually going slower, so that really doesn't count.

He said they used to turn it on while sitting on an overpass just to see how many brake lights they could count. (People with RADAR detectors seem to rapidly slow down when their device beeps.) The CHP cuts you a lot of slack, but some local police get carried away and light you up for a mile or two over. No matter what the police say, they have a 'quota' of tickets to get each day. They get chewed on if they don't write enough.

You should be able to get the records of the training the officer received and the calibration record of his RADAR. But, unless they are really screwed up, they have the proper records on file and up to date. Unless you are talking a lot of $$ or a suspension, it's hard to justify a fight. Easier with a good attorney, but that's expensive also.

[Doramius]

Some people haven't heard of it. And others don't know what it is, so they are wary of looking into it. My younger brother has Prepaid Legal along with my parents. They wrote a letter against a ticket, where he actually was in the wrong and speeding 18 over the posted limit. He just paid a reduced surcharge of $10 with no points on his license.

FYI - Always go to a traffic court in a clean and ironed white botton down shirt with ironed slacks, and even a tie. Look as professional as possible. And have enough money ($50 at the least) either in cash or check to pay at least 1/4 or more of the fines, if not the full amount. Judges will often throw out tickets for professional and respectful looking people. The courts are understanding if you cannot pay a full amount, but having a portion shows your interest to get it over with. When showing up for traffic court, the judge will reduce your fines greatly, vs. not showing up and be required to pay all the fines in full. I've seen a court reduce a woman's fines from $900 to $75 if she could pay the $75 that day. She spent all her money. She had 6 weeks in which she knew she needed to bring at least $100 to the court and she didn't save for it. The Judge asked if she could make a partial payment of $35. She said no. The judge decided to open her file for further review (so he hadn't even completely looked at it and she could have gotten off clean) and discovered that she had a previous ticket for driving without insurance. They judge upped the initial fines back to $900 and required her to come back for a hearing on the previous ticket and that she needed to have at least $250 with her or she would be held for 96 hours in the city jail. That girl dug her own grave.

[JohnnyCNote]

While these may be good as rules of thumb, don't forget that the ticket was issued in Australia, so US law really doesn't apply....

[CoasterCreator]

good point JCnote


go to the library or where ever you can acess to the current law ( maybe thepolice's dept wedsite) and start studing if you really want to beat it

[pacmania_2001]

Thanks all for the advice.

I was going 16km over the speed limit according to the ticket. I was caught by a speed camera which is basically a 4WD with a radar mounted in the back that automatically takes your picture if you are over the limit.

I still haven't decided whether or not I'm going to court, whilst I don't have to because I have enough points left on my licence I still think I should based on the dodgyness of the situation.

Have a look at the photo and see what you think. Cap, do you think the trees and the metal sign in between me and the camera could affect the radar?

[BJ_M]

no points is there for a picture speed camera -- because there is no way to say who was driving ..... at least it is that way in canada ...

[jimmalenko]

Are you in Queensland, pac ?

I was at the Gold Coast a few weeks ago, and on the way to dreamworld we saw firstly the sign warning drivers that the speed camera was in use, and then the unmarked vehicle some 20-odd metres down the road. I thought that was strange, because down here in Victoria, they hunt you like a P.I. We don't get any warning signs - cops hide behind overpasses, inbetween trees in the median strip, etc etc with no sign of the friendliest warning such as that sign in the picture above.

I seem to remember reading that speed camera photos taken from the front are inadmissible in court because they violate privacy laws, due to it being obvious from the front if you are not wearing a seatbelt, and it would be quite a conundrum for you to appear in court with a photo clearly showing you breaking the law, but not being charged for it. It may have been an urban legend, but it seems to ring a bell.

[pacmania_2001]

I'm a Queenslander.

What you described with the sign being clearly seen is a very rare occurence. Normally (as seen in the picture) you only see the sign once you've been caught.

I've also heard of the privacy thing with front on shots. The thing that pissed me off was that it was dark when I was driving and the thing flashed right in my eyes.

no points is there for a picture speed camera -- because there is no way to say who was driving ..... at least it is that way in canada ...

In Australia you can fill in a form saying that you werent driving but you have to nominate who was driving. If you say that you don't know who was driving they investigate you.

I can get away with no points if I wanted to by nominating my parents company and then under the company speeding fine laws pay 5x the money fine but get no points deducted.

Right now I'm just deciding what my options are for this.

I'm starting to think seriously though about carrying around a supply of signs in my boot that say "Speed Camera ahead, slow down" that I can put out before speed cameras to stop them revenue raising. Also I know of a certain speed camera around my area that the police like to leave unattended that might be a prime target for its number plates to be nicked.

[jimmalenko]

I wonder whether you are able to get guidelines for the safe placement of speed cameras or something from the police. Surely it would have been noted that a flash front-on could temporarily blind people and therefore create a traffic hazard. Not to mention epileptics.

[BJ_M]

epileptics would be triggered by a flashing strobe , not one flash

[pacmania_2001]

Tomorrow I'm talking to a specialist traffic lawyer to see what my chances are of winning a court case.

If he does say I've got a chance though I'll probably represent myself because of the lack of funding and the costs of a lawyer.

[glockjs]

isnt hiding behind trees entrapment?

i would have started by checking the serial numbers on the radar because it has to match to the officer issueing the ticket. at least thats how it is here.

[glockjs]

oh yeah...just an afterthough. next time that happens crash your car and claim that you were blinded and scared and sue the crap out of your local city

[pacmania_2001]

I don't think entrapment exists in Australian law, I know it doesn't exist in road enforcement.

If I'm driving again and a speed camera goes off in my eyes the operator is going to get an earful. Thats why I carry a large mag light in my car.

[Capmaster]

Thanks all for the advice.

I was going 16km over the speed limit according to the ticket. I was caught by a speed camera which is basically a 4WD with a radar mounted in the back that automatically takes your picture if you are over the limit.

I still haven't decided whether or not I'm going to court, whilst I don't have to because I have enough points left on my licence I still think I should based on the dodgyness of the situation.

Have a look at the photo and see what you think. Cap, do you think the trees and the metal sign in between me and the camera could affect the radar?

I don't know without knowing the antenna pattern on the gun.

Usually flat metal objects generate huge return signals. If that sign is metal there's no doubt multipath going on. But ...the gun probably discriminates out the "0 MPH" return signal and instead bumps up the amplification of the legit signal.

The tree's interference is probably a big factor, but the effect would be to dampen or cancel the return signal from anything behind the tree. It may return a weak signal, but see above for why that probably won't matter.

In that pic it looks like the officer has line-of-sight, but he's at an angle to the roadway so the doppler effect will be less than if he were on the shoulder pointing it straight back. It will read artificially lower in this case.

How fast were you going Pac?