What's the State of Car Radar Detectors?

Factual Questions
1

Back in the day, I remember these being fairly common in cars. Or at least not uncommon. Granted I’m just using my own anecdotal experience but I can’t think of anyone now who owns one. A quick look at Wiki shows they’re illegal in Virginia and DC and in other states restricted if it’s a commercial vehicle but generally allowed for private cars.

Are they still effective? Has technology outpaced them? Am I just missing the vibrant radar detector industry? I never owned one myself but I remember the old ones being sort of flaky and signalling for certain neon signs or other “noise”.

2

Instant-on radar guns have made radar detectors fairly useless. The police officer sits in his car and your radar detector can’t detect anything because there are no radar signals being generated. The officer sees you, presses the trigger on the radar gun, he gets a reading of your speed and your radar detector goes off (and if you are speeding you get a ticket). The only way you’ll detect the radar in advance is if there is someone ahead of you who gets lit up while your radar detector is in range of it.

Radar detectors still get a lot of false positives, not only because of radio noise generated by things like neon signs, but also because there are a lot of radar generators out there. Grocery store door openers use radar, for example, and on many highways there will be tiny inexpensive radar systems set up so that the traffic engineers can monitor the speeds so they know where traffic jams are occurring (in many places you can go online and see a real-time map which will show roads that have traffic problems in red so that you can avoid them). Traffic lights will even sometimes use radar instead of in-ground loop detectors. All of these sorts of things will set off a radar detector.

Many police departments also use laser, which a radar detector obviously won’t pick up. They make laser detectors, but they suffer not only from the same instant-on type problem, but also suffer from the fact that laser is much more directional. The laser beam strikes the car being measured and not much else (you get a little scattering and reflection but not much). Unlike radar, there just isn’t a whole lot of extra signal floating around for your detector to detect.

3

There are still ads for radar detectors in auto-enthusiast magazines like Car and Driver, particularly from a company called Valentine One. In their ads, they claim to be able to deal with many of the issues that engineer_comp_geek notes, but I have no idea if this is true.

4

No it’s not true. There is nothing that can detect a radar gun thats off. There is. Itching to detect when the trigger isn’t pulled. And once a laser detector is triggered it means it’s too late.

5

Well, saying they’re useless is a bit of an overstatement; technically, a radar detector is 100% accurate, in that if it gives you a warning beep, it’s definitely receiving a radar- or laser-frequency signal. The question is, is it coming from a police car, and is it too late to avoid a ticket? Like engineer_comp_geek said, other sources of radar-frequency signals are a huge issue. The best you can do is use your detector all the time (lots of people only use one on long trips, which doesn’t make a lot of sense; you do most of your driving close to home, so you should be using your detector there) and note to yourself the places where you get signals from non-police sources (“false positives”). Then, when you get a signal that’s “unusual”, you can presume that it may be the police. One factor working in favor of radar detectors is the inherent laziness of people, including police officers: it’s much easier for them to cruise down the street blasting radar at everyone than to set up a stop and select targets. And the former is much easier to avoid than the latter.

I still feel that the Valentine One is tops, because it uses two antennas, front and rear, and uses them to triangulate where the radar signal is coming from and count the number of signals in the area. That can save you if police are running radar in an area where you habitually get a “false positive”; if the display shows a “3” instead of a “2”, for example, you can guess something’s up. I used a V1 for years, and still have it, but I have a better way to avoid tickets now: I drive at a sensible speed.

6

What they seem to argue is that they have the range to detect that “instant-on” radar detector when it’s being used on the guy ahead of you (and, thus, give you a warning that there is a radar source ahead of you). Even if that’s true, it obviously doesn’t help you at all if the radar gun isn’t being used during the time it’s in range, but before it’s being used on you (i.e., you’re the only car on the road, or the cop isn’t checking every car).

7

The market for radar detectors has been largely reduced by the abandonment of the national 55 mph speed limit. Driving 55mph for hour after hour, across vast stretches of desert and prairie really was a sort of hell.

8

A lot depends upon the type of roads you are driving on and the traffic conditions at the time. If you are driving on an open stretch of freeway and there is little traffic you are vulnerable to instant on radar. If you are on the same type of road but driving with more traffic the detector can give you enough warning to slow down before the police can isolate your car as the one speeding.

I drive on mostly two lane rural roads and my Cobra radar/laser detector will pick up radar leakage around corners and over hills and I slow down before I ever see the actual police car. I am pretty sure they cannot get an accurate reading until my car is in line-of-sight.

Most of the police around here still keep their radar units on all the time and I can hear them coming a mile away. I have noticed one guy standing beside the road using a laser type gun but although I was going over 70 in a 55 I still recieved an alert in time to slow down. I think this was while he was aiming at the cars in front of me.

Radar detectors are just a way to be alerted when there are police around, they aren’t insurance against getting stopped. If most of your driving is done in urban areas they are next to worthless due to all the false alarms.

9

Generally, though, if there are cars in front of you, they are able to see the police officer and slow down (usually causing an accordion-style effect) that makes you go well below the speed limit by the time you pass the officer.

When you are car #1, you get nailed.

10

I have a Valentine 1. It cost me $400 about 9 years ago, and it probably saved me from about one ticket every year, which I would definitely consider worth the price. On the other hand, I have gotten three or four actual tickets in that period, so it is not foolproof. Most of those were from cops using laser on the highway.

While laser and instant-on radar are used a lot on the highway, a lot of cops have vehicle-mounted radar guns, which they will leave on while driving, or just while parked on the side of the road. The V1 works great for those - it is very sensitive (sometimes alerting you several miles in advance), and the directional arrows are a must-have for ruling out false alarms.

False alarms are definitely a problem, but once you’ve used the thing for a while, you learn to distinguish the pattern of a false alarm from a genuine signal. I mounted mine at the top of my windshield, right next to my rearview mirror, so that I could easily see the lights, and generally kept the volume turned off.

It is technically possible for your detector to detect even instant-on radar and laser guns, if the cop aims for the car in front of you first and you pick up some of the scattered signal. Obviously, if you’re the only car on the highway, you can’t depend on that.

The other major radar detector brands are worthless, in my opinion, because they don’t have the arrows. Cordless detectors are especially worthless - to save power, they do not run the receiver circuit all the time, and so they are less sensitive and take longer to alert than corded models.

Radar jammers are illegal in all states, as radar emissions are regulated by the FCC. Laser jammers are widely available, however, because they use simple infrared LEDs, which are not regulated. I considered buying one, but decided it was best not to enable my speeding habit any further.

11

I don’t think that even ‘back in the day’ radar detectors were ever mainstream, they were and still are a niche product. Maybe a slightly smaller niche today for the reasons stated above, namely the prevalence of higher tech police equipment and the repeal of the 55 MPH limit.

And, IMO, they’ll remain a limited appeal item because they’ll never be plug n’ play reliable. And because the vast majority of drivers in the US don’t deliberately speed on a regular basis. Years ago Letterman, who liked to drive high-end sports cars really fast on his daily commute from New Canaan CT to Manhattan (he eventually got his license suspended for it), did a remote piece in his car featuring his radar detector. When it went off and he pointed out the cop car to the camera he said it was, “Kind of like fly fishing”!

12

Laser jammers are illegal in some states:

http://www.guysoflidar.com/usa-laser-jammer-laws.html

But as far as I know it is not difficult to get away with using one. All you have to do is turn it off as soon as you slow down and it would not be possible to tell whether or not you were actual speeding since by the time the cop did get a reading you would be going the speed limit.

Laser jammers can also be used as park assist sensors so even if you are caught with one you might be able to use that as an excuse for having one.

13

Are there detectors that instead monitor for cop cars, perhaps via transmissions on cop frequencies or acknowledgments packets on digital receivers?

14

I recall that quite a few years back either the VA or MD state police were talking about engaging in a kind of electronic warfare on the DC Beltway. There were plans to install radar emitters all around the Beltway, not to catch an ticket anyone, just to set off radar detectors and spoof people into slowing down.

This was shortly before I moved out of the area. Does anyone know if they actually did it?

15

Some of the newer radar detectors also have a database feature and GPS. The new Escort, for instance, allows you to download a database of known speed traps and speed cameras (according to their criteria, so it’s not just some schlub peppering the database with fakes to cause havoc) which will cause your detector to alert you as you approach them. This is a second layer of protection, although it requires a subscription so it comes at a cost.

The reality of it is that a radar detector won’t do you a whole lot of good unless you’re dealing with police with older equipment or you’re in decently busy traffic and it catches a reflection off of the guy in front of you. They are fairly sensitive, but as was said earlier they can’t detect something that’s not already operating. In other words, it won’t help in West Texas or at 3 a.m. when nobody else is on the road.

Nevertheless, it needs only warn you 3 or 4 times for it to pay for itself, so it’s for you to decide if it’s a sound investment or not. Personally, I’m all for it. Anything that helps keep the fuzz from taxing you is worth it. If you’re going 90 in a 65, you deserve to be caught. If you’re doing 70 in a 65 that little beep to make you slow down makes you a bit safer and a lot less poor at the hands of the revenooers.

16

Police band radio detectors used to be advertised in all the major car magazines. They had to be tuned to the band the local cops were using. The detector came with a list of most of the frequencies of the major police departments in the U.S.

Haven’t seen them advertised since probably the late eighties, but I may have missed them.

17

Police scanners are alive and well, but pretty much useless for avoiding speeding tickets. If a cop is sitting on the side of the road trying to catch speeders, he’s not talking on the radio. And even if he’s driving around town somewhere and announces his position on the radio for whatever reason, that information is useless to you unless you know the exact geography of the place you’re speeding through.

18

Has anyone tried the passive approach and designed a car using stealth technology? The proper shape and a radar-absorbent paint job would be just the thing for a rich leadfoot who cries, “Millions for defense, but not one red cent in tickets!” :slight_smile:

19

Mythbusters tried it, without success. Now, if you want to invest millions, you might be able to build something, but not for a dollar six bits.

20

Car And Driver, IIRC, had an article about that back in the late 80’s. They ordered the material from the guys who made stealth material for cruise missiles. Apparently, it was a foam about half an inch thick, with carbon or metal particles embedded. The theory was that you get reflections equally from all the way through the material. It’s a half a wavelength thick or more, so the reflections cancel each other out, sort of like damping effect of a rough shoreline not reflecting waves in the water the way a flat wall would.

So they took a Porsche which already had a radar-unfriendly sloping front, added a rough bra of this stuff, and did some radar tests. Their conclusion - it would make the car undetectable by the guns of the day until it was about 400 feet away. If by then you hadn’t seen the police and slowed down, you need a ticket for lack of attention.

Of course, that does nothing for a front license plate, meant to be reflective and the prime target for laser guns today. Also, the physics of radar reflection mean that some things simply can’t be easily radar-proofed without geekily modifying the body; and the cop hiding behind something and catching you from the back can still nail you. Unless you are Dave Letterman and need and want to finance a full-body car makeover in custom fibreglass and foam, it’s probably not that practical. Perhaps the best thing you could do is apply something that makes your license-plate less reflective than a bright-yellow road sign, but that would probably be illegal tampering.

I have seen ads in some places for a GPS device with a database of local red-light cameras, which are actually speed cameras with a red-light detection bonus and excuse for being. It will beep to warn you to slow down when approaching them.

I suppose the issue with laser jammers is - do they also have a detection mechanism? If they do, technically they probably qualify as illegal too. If not, then they are always on which will give the cop a hint to give you the once-over just in case.