Sorry about the death in the family Tony.

On my older K-band radar gun, without much interference from other moving targets or frequencies, I can pick up a car over a mile away. Of course the smaller the target, the closer they have to be. Officers are only supposed to write tickets for cars clocked within 1/4 mile. Although we know all cops don't play by the rules...

 

The correct procedure, at least here in Washington State is this:

The officer should be alterted, or prompted if you will, by visually observing a speeding vehicle. They should then estimate the vehicle's speed based on their observations. This is considered a presumed fact. The radar should then be used to confirm the officer's observation and estimation. This would then be considered a proven fact.

The reason for this procedure is that although radars are extremely accurate, the readings they display don't always correspond to what the officer attributes them to. Any speed reading on the radar is the result of a vald signal it has received. However, the officer's job is to then pair the reading on the radar with the correct vehicle. This is where human error comes into play.

For example. If I pointed my radar gun at a neon sign, I might get a reading of 138 mph (or some other weird speed, or possibly nothing at all). The neon sign is probably producing some harmonic of a frequency that the radar is seeing as 138 mph (FYI he'd probably have to be parked right next to the sign). Now - it will get this reading regardless of whether there are any moving cars in the area. If there are none nearby, then it's easy to surmise that the neon sign is causing the reading. But if it gets this reading when a car is approaching the officer behind the line-of-sight of the sign, the officer may think that the car is coming at him at 138 mph. But hopefully he'll be able to tell that the car is not actually going that fast (unless of course it IS going that fast) and he'll also know not to point his radar gun at neon signs and expect it not to get some weird speed reading. In other words, if the officer saw a car approaching him at about 40 mph and got a 138 mph reading, he'd immediately know something was up.

It should not be the other way around. The officer should not be alerted by the radar that a vehicle is speeding. If he did, then he'd be very tempted to rely on the radar as fact, without his human observations. He'd get a 138 mph reading on the car and think, "Gee...that car is hauling butt" and accept it without using his brain.

The same thing applies to radaring two or more cars at the same time. If he sees a maroon Maxima speeding down the highway and passing a silver Civic, and he's getting two speed readings, one of which is let's say 76 mph and the other is 60 mph, then logically the Maxima is the car the radar is measuring at 76 and the silver Civic at 60.

It's also important to note that although the neon sign might give a high reading in the absense of a valid target vehicle, this reading will be overcome when an actual moving vehicle approaches close enough to the radar. And it's even more important to to add (if I haven't already done so in a previous post) that a valid target vehicle will produce a clear and coherent audio doppler tone on the radar gun. A neon sign (or any other interference) will NOT. An audio doppler tone is a sound that the radar makes that corresponds to the speed that is displayed. The higher the speed, the higher the pitch of the tone. This tone is another required procedure, or element, of correct radar use.

Tony

 

Maybe. This is probably dependent on the department's policies and the policies of the neighboring departments.


More than likely, yes. I do it all the time. It doesn't mean everyone can. Like above, this depends on the departments that are involved.

Maybe. I've done that before, too. Lately, we've been instructed to not cite the person at the location outside of our state and to issue them one later via mail. Of course, that officer could call his officer buddies in the state he's chased the car into, and have THEM issue the citations on his behalf. I assume these sorts of situations would vary greatly by location.

Tony

 

More than likely. But once again this would depend on that department's policies and the policies of the department he happens to travel into.

Tony

 

another quick question Tony, today i was driving in the left lane going about ~80 or so (i know i was speeding ). there was a HPD motorcycle ahead of me, and i was just keeping pace for a good stretch on I-10. anyhow, after i drove over this overpass, my 8500 screamed laser at me, and sure enough, there was a HPD squad car parked, officer standing outside with his radar gun aimed at me. So i thought oh crap he got me for sure. but he didn't pull me over, but pulled over this other car instead. my question is...how wide is the laser beam? i thought laser beams are pretty narrow. i'm guessing i was about 1000 yards out when my 8500 went nuts.

Thanks for all the informative replies!

 

AT 1,000 yards (over a half mile) a lidar beam will be about 9 feet wide. Sounds like he got you, but he also got someone else and decided to go after them instead?

Tony

 

Thanks for creating this thread, Tony. It's pretty much informed me of everything I could ever need to know about using a radar detector. I have a few questions about the radar guns though.

Does a radar gun aimed at a pack of cars pick up only the fastest moving vehicle? You said, "If he sees a maroon Maxima speeding down the highway and passing a silver Civic, and he's getting two speed readings, one of which is let's say 76 mph and the other is 60 mph, then logically the Maxima is the car the radar is measuring at 76 and the silver Civic at 60." Does this mean that a gun will pick up both signals and display both and the officer just decides which looks like it is going faster?

Also, if you were clocking a car in a pack of vehicles and one of the cars visibly slowed down after you got your reading, would you go after the guy who slowed or a remaining vehicle that looked like it was going faster?

 

No. The largest determining factor that will affect which vehicle the radar will pick up is size. If two vehicles are approaching and one is larger than the other, (and all else is equal) the radar will pick up the larger one.

Then there's distance. The farther away a vehicle is, the less likely it will be picked up. There's a principle known as the inverse square law that says that if the distance is doubled, then the strength of the returned radar beam is reduced by a factor of four. In other words, if a sedan was approaching the radar at 100 feet and a very large truck with 4 times the reflective area (just an example for illustrative purposes) was approaching at 400 feet, (and all else was equal) they'd be picked up by the radar equally. Distance is not as important as size.

And then there's speed. All else being equal, the radar will tend to display the vehicle with the highest speed. This factor is the least important when compared to size and distance.

However, some radars can be set up to only display the fastest speed. In other words, if five cars are approaching it will only display the fastest car's speed. Of course, what it won't tell the officer is which car is doing that speed.

Possibly. In the above examples there can be all sorts of situations where the returned signal from different cars will be of such similar strength that the radar will be constantly toggling back and forth displaying the speed of different targets. And of course, as a group of cars approach, their positions, speeds and distances don't remain constant in relation to the radar gun and therefore they will vary in their respective signal strengths. A trained officer that is doing a proper job of observing traffic should be very accurate in being able to pick out which car is doing what. It's really not that hard and after doing it hour after hour for however long (10 years for me) it becomes like second nature.

HOWEVER. Another thing that is taught (and I really can't emphasize this enough to my students) is that if you are not 100% sure that the person you're about to give a ticket to is doing what you say they were doing - don't give them a ticket! I can't speak for all officers, but this is extremely important to me on many levels. No one ever wants to get a ticket and certainly never, ever does anyone want to get a ticket for something they didn't do. It's never that important for me to have to write a ticket if I'm not completely certain. It's just as easy for me to let someone go with a warning.


That's one heck of a question and I'm not sure I can give you a simple answer. If someone slows down suddenly it might mean they realized they were speeding and decided to slow down, or they saw the officer and slowed down to avoid a ticket, or they had a radar detector and slowed down to avoid a ticket. (On a side note, I find it quite amusing to radar people with radar detectors and watch them slam on their brakes even if they're already doing at or below the speed limit). If someone slowed down because they realized they were speeding (or some other reason - like they just finished passing someone, etc) then that's a good thing. If someone slowed down because they saw the cop then that's what we as police officers want - if we could never give a single ticket and get people to slow down and drive more responsibly then we ALL win, right? However, if someone slowed down because their radar detector went off, then those are the ones that will get tickets 99% of the time. Those are the people, in my opinion, that deserve speeding tickets the most. On the opposite side of the spectrum, there are people that go speeding by and don't reduce their speed one bit even after they see the officer. Are they just trying to prove a point, that they know what they're doing? Or are they so oblivious that they didn't actually even see the police car on the side of the road? Interesting to say the least. I'd be much more likely to watch someone go speeding by without slowing down and not pull them over on the highway than if they did the same thing in a school zone. Make sense? In other words, there's no one, single answer to your question. It just all depends on the situation.

Tony

 

Superb and speedy responses. Thank you very much.

 

very god info what do you think about the escort solo s2? this is the radar that i own

 

Please ask about radar detectors in another thread. This is an informational thread about radar theory & operation.

Tony

 

It is the best cordless detector they make but it doesn't detect POP radar and it loses by 1/3-2/3 of a mile in radar detection to the Valentine One. Also, why would you want to change batteries all the time when you could just hardwire the Valentine One and have much better detection?

http://valentine1.com/cordless/

http://radarbusters.com/support/product-tests/2.asp