Tested: Radar Detectors vs. the Latest Photo Radar

After our first test two decades ago against the most common photo radar (mobile speed camera) technology, two things became clear: 1) Most radar detectors give little advance warning of it and, 2) There are some exceptions, but you won't find them in the closeout bin at Sam's Club.

We've been testing radar detectors against these rolling ticket machines since 1991 and despite advances in radar detection, they're no easier to handle today. The latest radar used by Redflex and others is an imported TTL-pulsed, low-powered K-band unit that's exceptionally difficult to detect. Most detectors can't spot it from across a six-lane freeway.

By its nature, mobile photo radar is a headache for radar detectors. Unlike conventional traffic (speed) radar, this is short-range stuff; it typically reads a target speed when the vehicle is within about 90 feet. This is a fraction of moving radar's 3,000-foot-plus maximum target range. With no need for long range, photo radar can likewise use a fraction of the power found in conventional radar, which typically use 30 to 50 mW (milliwatts). The spec sheet for the latest Redflex photo radar lists power output as 5 mW; we've seen others as low as 2 mW.

At these miniscule power levels, a radar detector's job gets considerably tougher. Just as it's easier for a radio to find a 50,000-watt station than one with a paltry 2,000 watts, detectors also prefer a louder signal source. But there's an additional headache to be surmounted.

That's beam width and direction. For reference' sake, keep in mind that the latest Ka-band police radar have beam widths averaging 12 degrees. The beam is also directed straight down the road, toward a detector. Under these circumstances it's not unusual to get an alert from miles away.

But photo radar is aimed at a shallow 20-to-22-degree angle across the road, necessary to determine which target the radar is reading. And it's very narrow—5 degrees horizontally, typically—also to assist with target ID.

In states like Arizona that hold the driver responsible for his car's misdeeds, the driver's face must be photographed.

The money shot from a Redflex photo radar camera in Phoenix. A pseudo-ticket for $181.50 is mailed to the registered owner who, under Arizona state law, isn't required to respond. Once this became known, disgusted Arizonans ignored their tickets in droves.

These two factors—an ultra-low-powered signal aimed away from the detector—combine to seriously complicate the detector's task. So it's no surprise that models that perform well against conventional radar often falter badly when trying to combat photo radar.

During testing we noted significant variations in the detection range of some of the test samples. Much of this was due to the radar van's location—along an eight-lane freeway—and the freeway's constantly-changing background, a variety of reflective objects including heavy big-rig traffic. When these 18-wheelers rumbled past the radar van, they momentarily blocked the radar signal. An instant later, the signal was amplified as it was reflected from the truck trailer.

When you're dealing with a miniscule power output and a directional beam aimed across the road, little things like this matter. (Merely placing the target vehicle in lane one, closest to the median, rather than lane four will effectively neutralize detectors whose antennas have a limited field of view, for instance.) Anticipating these fluctuations in detection range, we made four runs with each radar detector and averaged them.

We tested a mix of mid-priced and high-end models, focusing on GPS-enabled units and on those we knew from past tests are unusually hot K-band performers. Retail prices ranged from about $300 to $500. Since the target vehicle had an Escort Passport SRX ($1,100) custom-installed unit already built-in, we recorded its score as well, but only for comparison purposes. Here's what we found.

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Of the non-GPS group, the Escort Passport RedLine ($499) proved to be the best protection you can buy against this K-band photo radar, delivering 1,220 feet of warning distance. It was followed closely by the Valentine One ($399) at 1,196 feet and the $339 BEL (Beltronics) RX65 (1,178 feet). Another BEL, the STi Magnum [previously called STi Driver] ($470) trailed its Pro-Series sibling by a few percentage points.

Escort Redline: world's best at spotting K-band photo radar. It's equally adept at countering Ka-band photo radar, not to mention every type of conventional traffic radar.

Among GPS-enabled radar detectors the BEL (Beltronics) GX65 ($469) and Escort Passport 9500ix ($499) both delivered good range, upward of twice that of the competing Cobra XRS R10G ($469) and the $389 XRS 9960G (an updated XRS 9950 that's the subject of an earlier test and review.)

At less than 500 feet, on average, under optimal conditions—about 4.5 seconds of warning at 75 mph—drivers packing one of these Cobras would need to remain on high alert and react instantly to warnings.

These two Cobra GPS-enabled radar detectors experienced greater success against conventional K-band radar in our last shootout but as noted, detecting this new pulsed photo radar is a far tougher job.

Study the scores and it's clear that this is one threat where an otherwise-capable detector can't help much. You'll need a detector with outstanding performance to counter this increasingly common type of stealth radar.