AZ DPS Mobile Speed Units Hard To Detect


I started using my Escort Passport 8500 X50 to see how it worked with the DPS Mobile Radar units. I am not impressed with the performance. This is by no means a scientific test but don't count on your radar detector to reliably notify you in time when you come up on one. I was able to check it against five different units in various locations and each time all I received was a VERY LOW beep with only 1 bar showing and that was when I was within a couple hundred feet of the unit. The Passport indicated it was a K-band signal. If it wasn't for the yellow warning signs before coming up on the units and I was speeding, it would have been too late to slow down (I drive about 67-68mph). I wouldn't put any faith in the radar detectors protecting you from the DPS freeway units. Almost makes one wonder if the radar detectors are worth the $ anymore. I get more use out of my Redlight POI's on my GPS than the radar detector.

-- where the heck am I?

I have observed the same situation


The signs are usually well placed and the one-half mile and 300 foot distance warnings have been adequate enough to slow me down. My Escort barely registers any detection when I pass one of the vans.

I saw one coming back from Gila Bend a few months ago and the stobe was doing just that. It looked like a beacon rather than a strobe flash. I don't think that van caught very many speeders by surprise. So much for trying to be stealthy!

If folks miss the signs while speeding, then they might need to be paying closer attention to the road and their driving.

Watch For The Signs...sometimes.

Out of the 5 units, one unit had only one sign out and it was only a couple of hundred feet from the truck. That wouldn't have given a driver enough time to adjust their speed. Around here they aren't very consistent with the signage.

-- where the heck am I?

Low Power

I've heard that the mobile and stationary photo radar units transmit at a much lower power level than a typical police officer running radar. I think this is because they are usually (or at least think they are) being stealthy enough that they need only transmit at low power to get a quick clock on your speed, then take the photo. Additionally, it's probably to give those of us with radar detectors less of a chance to slow down.

I bought a Valentine One about a month ago, but I haven't run into any photo radar (mobile or otherwise) as of yet. I'm depending on the V1 to pick it up with enough warning.

About a year ago, I borrowed a friends V1 for a 1,300 mile trip. The only photo radar I ran into was on the way back in Colorado. I got a K-band signal and about 3/4-mile later through some trees, around a curve and on the other side of an overpass, there it was. I was looking for a cop and was really confused to see the signs and camera, at least in that part of Colorado. At one point I was picking up Ka-band for a little over two miles in the hills of western Oklahoma before I finally saw the local small town police clocking people on the edge of town. Obviously, they must have been running their radars in constant full power operation.

The V1 usually picks up those trailers with signs that show your speed from over a mile away. Most of them run K-band.

I drive the SR 51

I drive the SR 51 in Phoenix at least three times per week and always see the signs posted properly. Additionally I have seen the mobile units on Carefree Highway between the I-17 and Lake Pleasant on my last four commutes between Phoenix and Vegas and they had the signs posted correctly.

pkdmslf, you must be catching the mobile radar operators when they are either setting up or taking down the radar! Or maybe they are on lunch or donut break when you are traveling by.

In my personal experiences I can recall only one instance when the signs were not posted and the mobile van was leaving the setup and moving to another location.

Same here

My experience with those Photo Radar Vans has been similar too.

Both my Valentine and Bel 985 give very little warning - maybe 200 feet or so depending on the area.

I heard the same thing that clmathes did. They are low powered and also the 'gun' is angled low across the road. I get less warning if there are no buildings or walls for the signal to bounce off of. Pima and Dynamite is one of those areas. It's mostly scrub type brush.

Last weekend I was driving home from Laughlin and saw the Carefree Hwy Van. I saw the warning signs they put out but had to laugh. They set up shop just after the speed dropped 45mph.

Oh - If you are traveling in Scottsdale they publish where the Vans will be. Just Google Scottsdale photo radar vans. Tempe also publishes their schedule. I haven't found a link for the DPS/Freeway units. Those are the ones that I worry about.

Marty publishes publishes where the vans are going to be.

BTW I saw a phoenix radar van for the first time recently!

-- - red light cameras do not work

Well, I removed my radar

Well, I removed my radar detector after a week of "testing" with the DPS portable units. The radar detector did not detect any of the mobile units until I was right up on them and then I received just a low level K-band hit (1 bar). Each time I saw the the mobile unit well before the radar unit did. It does pick up the vans on the surface streets and the police/highway patrol vehicles that are using their active radars in their vehicles though. As far as the freeway units, it's useless.

-- where the heck am I?


I finally got that chance to do some driving in and around Phoenix yesterday. I encountered two of the Department of Public Revenue...I mean "Safety" mobile camera units. In both cases, the signs were up and gave plenty of visual warning.

My radar detector gave around an estimated 300 to 500 foot (K-band) warning each time. Not much at all, but if you're paying attention and not driving too much over the limit, it should be enough time to slow down to at least within around 5 mph over, which I assume would not be a ticket. Judging by the way my radar detector reported the signal, the radar on the DPS unit isn't actually clocking your speed until you're within about 150 feet. That's about where my detector was reporting a fairly strong signal before quickly jumping to a maximum strength signal within the next 50 feet and just a fraction of a second later. It's just a really low powered radar angled across the road and aimed down so that it doesn't have the chance to emit the signal farther up the road. Besides the fact that the radar and camera combination probably works quite well this way, the low power and angling of the radar is also seemingly an effort to defeat radar detectors and therefore increase the chance of generating more revenue.

It was interesting to see how drivers have adapted to the cameras (both stationary and mobile), especially in the areas where the speed limit is a painfully low 55 mph on a 6-8 lane highway. Traffic would slow down for the cameras, then speed right back up to usually around 10 mph over the limit. To me, this is obviously an indication that the speed limits have been set artificially low (most likely in an effort to generate more revenue) and not in line with the 85th percentile that traffic studies have shown works best. I also noticed that speed limit signs were relatively sparse, and the limit jumped around a lot between 55 and 65 mph for no apparent reason.

Either way, it was very interesting driving around the Phoenix area. Not only am I glad I had my GPS loaded with the camera files, but I'm also glad I had my radar/lidar detector as there was still plenty of highway patrol action going on. I encountered a total of four highway patrol cars running Ka-band radar, three of which had vehicles pulled over. The other was sitting at a slight angle on the side of the road outside of Phoenix in total darkness, lights off, hitting traffic with instant-on radar.

So, anyway, just thought I'd share my experiences.


I know this is a very old thread, but in case anyone cares, I have some new information about photo radar.

It seems that most photo radar, including the Arizona DPS mobile units, use a "horizontally polarized" signal. And, apparently, radar detectors are "vertically polarized" when mounted normally (in a horizontal position). This, in combination with the low power and angling of the radar unit, makes it extremely difficult to detect the signal with any kind of advanced warning. In most tests, mounting the radar detector vertically increases the warning distance by 5x or greater. I've seen this type of vertical mounting before, but wasn't sure exactly why they were doing it (besides the increased warning distance the detectors gave, but there was no mention of the polarization of the radar). Most of this information came from: (they admit that their tests are to be taken with a grain of salt, but I'm inclined to believe that the tests they've performed are relatively accurate)

Personally, I don't see myself going out and buying a special bracket to mount my detector vertically, but it's nice to know that it improves performance in regards to the DPS mobile units. And, since every DPS unit I've seen places the signs well in advance, there really isn't a need. Not to mention, you don't have to pay the ticket, anyway.