24Ghz ACC/ADAS Systems Causes Most Radar Detectors to False with Very Strong 24 Ghz K-band Alerts

UPDATED 21 MAY 07:

Since we first observed the falsing behavior of K-band with a late model Valentine 1, when in the proximity of an Audi Q7 last week, we have been working non-stop on improving our understanding of the dynamics of the Q7's system and believe now to have a much better handle on the situation.

Thanks to the participation of Don Rosen Imports - a respected Porsche and Audi dealer located in the Delaware Valley of Pennsylvania - that I am able to report these findings.

Here's what we've learned after an intensive two days of field-research driving with an actual 2007 Audi Q7 SUV, which was outfitted with the optional side-assist system.

The Good: As of today, the Valentine 1 does appear to have the ability to filter out, most effectively, the falsing that is attributed to this system (by giving up POP reception to both bands as K-band POP can not be programmatically disabled on an individual basis), the STi Driver in either reception mode does almost equally well while retaining POP-reception capability (appears primarily limited to Ka-band only) as did the Escort Passport 9500i (appears completely limited to Ka POP only) which did not alert in any event.

As VR had personally suggested, by disabling the J-feature (both-band POP reception capability, called POP2) the Valentine 1 will cease to alert even when one is extremely close to the vehicle and that includes inside the confines of the Q7, itself. We may have gotten a brief warning from the rear side with J-disabled as we made an approach from behind and once from inside the cabin itself, but as it happened only two times throughout out entire testing of both days, so we weren't really concerned. It appears to essentially be a non-issue with J-disabled.

So, no need to go out and get another radar detector (mea kulpa), if you've own a late model V1, just for this vehicle.

The reason that both of the other detectors (STi Driver and Passport 9500i) can operate with POP reception enabled without much fuss is both of them possess a much lesser sensitivity to K-band POP signal profiles than does the V1's with POP2 reception and is by far the most sensitive radar detector currently available to K-band POP police radar -- which the Audi's side-assist most closely emulates.

The Bad: All other late model radar detectors tested (which includes the Beltronics RX-65 Pro, Escort Passport 8500 X50, Cobra XRS-9700, Whistler Pro 73) do not appear to have the ability to filter out this signal. We tried every combination possible with all these radar detectors and were not able to stop the falsing in any event. Here's what we found, specifically:

Beltronics STi Driver: in either autoscan or highway mode with either POP enabled or disabled, the STi did, in fact, alert only occasionally to the presence of the Audi during our driving route - in which we followed the Q7, in our own vehicle, on the highway. Of all of the other detectors which alerted one or more times, the STi appeared most resistant to falsing for reasons already stated.

Beltronics RX-65 Pro: in either autoscan or highway mode with either POP enabled or disabled, with either Ka USA or KA Intl (remember side assist operates on K-band), the RX65 Pro did, in fact, alert almost continuously, at high levels, to the presence of the Audi during our driving route when we followed from behind.

Escort Passport 8500 X50: once again, in either autoscan or highway mode with either POP enabled or disabled, the 8500 X50 did, in fact, alert almost continuously, at high levels, to the presence of the Audi during our driving route when we followed from behind.

Escort Passport 9500i: we were not able to get the 9500i to alert in any event, but our particular detector is so new, I believe it may be going through a "tweaking" period. It could also mean that this latest detector from Escort is the most adept at discerning this signal and is effectively filtering it out, but if VR's assertion is correct, as we believe it is, it's more likely due to the fact that this new radar detector does not appear to possess the ability to detect K-band POP.

With the V1 (J-feature enabled -- it's default operating mode), RX-65 Pro, STi Driver (to a much much lesser extent), and the 8500 X50 the signal ramp appears to rise for a period and then fall briefly before rising again from time to time when in a consistent distance to the Q7.

The Valentine tends to report the source of the signal as if originating from the rear and then moves between the side and front even when the Q7 is well ahead on the road. This is probably due to the fact that vehicles behind us, made good reflectors of the radar signal back to our rear.

In deference to both Cobra and Whistler we examined the behavior a one detector model from each manufacturer and this is what I found:

Cobra XRS-9700: regardless of whether the detector was set to either highway or city mode with either POP enabled or disabled, the XRS-9700 did, in fact, alert continuously to the presence of the Audi with strong K-band when in close proximity to the Q7's rear. Further it sometimes alerted to the presence of SPECTRE (RDD) when enabled to do so.

Whistler Pro 73: regardless of whether the detector was set to either highway or any of it's city modes with either POP enabled or disabled, the PRO 73 did, in fact, alert continuously to the presence of the Audi with strong K-band when in close proximity to the Q7's rear and sometimes mis-identified the band at this range as Ka making it appear that two bands were present, both K and Ka. We even got a brief alert of X-band one time.

Also to be absolutely thorough, we accessed the behavior of an older Valentine 1 (v1.7) that was fabricated prior to POP reception and hence it remained absolutely quiet in all cases. We did notice again a brief strong-alert to K-band from my 3.826 version when J was disabled a couple of times, but certainly not the extent that it would have any real negative impact.

And for the sake of curiosity, we accessed the performance of an original and still functioning Escort Passport radar detector from the 80's. It appeared to briefly alert to the presence of K-band when the Audi's system was initially engaged and then remained silent.

Since the Beltronics and Escort radar detectors have the unique ability to display the actual frequency that is causing an alert, we tried to ascertain that additional information from the Q7's system as well.

When in threat display mode, the Bel and Escort models generally showed two bogies at continuously varying signal strengths and the Valentine had alerted up to 6 distinct radar sources, particularly when very close to the Q7's rear.

The distance, behind the Q7, at which point the V1, 8500 X50, or RX65 Pro initially alerted, appeared to be in the range of about 400 feet to 1000 feet apart, depending on factors such as curvature of the road; how many vehicles were between us and it; and appeared to last only about two car lengths once we passed by the Q7.

Unfortunately, all of the detectors we tested, also briefly alerted to the Q7 when it traveled in an opposite direction on a divided highway as we headed the other way.

Both the Beltronics RX65-Pro and the Escort Passport 8500 X50 where able to identify most if not all of the radar frequencies that were transmitted from each side of the Q7's side-assist radar transponders. We believe there may be approximately six of them and they are each tuned to a slightly different frequency (in the close-range of K-band) or there are only several of them which utilize an ever-changing frequency center.

According the Bel RX65 Pro, when in TEC display mode, were receiving five distinct signals each separated by about .020 Ghz at: 24.089 Ghz, 24.109 Ghz, 24.129 Ghz, 24.150 Ghz, and 24.169 Ghz.

According the Escort 8500 X50, when in TEC display mode, we were receiving six distinct signals each separated by about .016 Ghz at: 24.082Ghz, 24.085 Ghz (probably the same as the previous one) , 24.100 Ghz, 24.116 Ghz, 24.150 Ghz, 24.166 Ghz, and 24.182 Ghz.

In either case, it appears that Audi's side-assist utilizes multiple frequencies and transponder heads to perform its function.

The Ugly: Our worst fears were confirmed when we actually drove with the Q7 with side-assist enabled. Other than the Valentine 1 (when its J-function was set to disable) and the STi Driver (which doesn't appear to consistently spot these waveforms) each and every other production detector from the premium/ultra-premium group (the Escort 8500 X50, RX-65 Pro) was unusable inside the vehicle as they alert continuously to multiple K-band sources at high signal strength levels. Had it not been for the V1's J-function disable ability, the Valentine 1 would also be unusable in the vehicle when the side-assist is enabled.

We couldn't get the XRS-9700 to alert when mounted on the windshield inside the Q7 while the side-assist system was engaged. The Pro 73 alerted for short periods of time when mounted on the windshield inside the vehicle when the system was engaged. This was due to the fact that these more affordable 2nd tier performance group of detectors, generally provide reduced sensitivity as compared to the more expensive premium or ultra-premium group of radar detectors that will likely find there way into the interiors of these high performance vehicles.

I would expect the top two best remote installation radar detector lines -- which would be entirely appropriate with this caliber of vehicle -- the Beltronics RX75 and the Escort Passport SR7 -- would be OK as long as they were installed or enabled with their FRONT sensors only. I suspect even with the super-sensitive forward facing radar antennae these two systems provide, when mounted low in the front would likely not pick up the signal from the rear of the vehicle, as the vehicle itself would block just about any stray signal that could possibly find its way to them from the rear facing side-assist transponders.

On the other hand, I would expect the concurrent operation of side-assist and the rear radar antennae of these top-performing remote install detectors to actually cause a perpetual false.

Install shops, should be aware of this high possibility before they end up with very angry customers who just dropped a $1000 (for detector only) or $1500 (for detector/jammer combination) for installation of either models into their Audis.

Fortunately, for drivers of the Q7 who own one of these high-end radar detectors (either windshield mounted or remote installed), the system can be easily disabled with a quick push of a button located by the driver's side left door handle making their usage possible.

The side-assist system -- which is distinctly different from the Distronic system that is making it's appearance in other models and marques -- will be appearing in other future Audi vehicles, we've been told. The next vehicle slated to have it available, will be the 2008 Audi A6, again as an option (perhaps packaged along with Audi's Tech packages).

And since Audi is the a technological leader of German engineered vehicles, I would not be surprised to see a version of this system appear with perhaps a future model of the Porsche Cayenne; the likes of a Lamborghini Gallardo or Murciélago; VW vehicles such as the Touareg or Phaeton; and perhaps a future Bentley GT.

It's not clear whose system Audi uses, at this moment, but these new systems will be continuing to come online just as ABS braking did when it was first introduced -- which is so common-place today as a safety enhancement feature. One very knowledgeable forum member of RD.NET has suggested that the actual transponder module may be manufactured by Hella and after subsequent research, this appears to be the case (under FCC# NBG009014) . Other similar models are by Valeo , Continental, Siemens, Tyco, and Visteon will be some [they're more] of the additional manufacturers providing systems to other automotive companies, as well. Most of these devices appear to coming from manufacturers located in Germany -- a country which has little use for radar detectors -- which may explain why the interference potential has been overlooked and/or not taken into account.

Upon further research, it appears the selection of 24Ghz for certain ACC/ADAS devices by their respective manufacturers may have been, in part, driven by a well-intended cost savings measure, without much regard to it's potential impact upon other radar detector equipped vehicles and therefore, the natural flow of traffic these systems intend to enhance. To be frank, using 24.1Ghz (more generally referred to as 24 Ghz) with an automated cruise control mechanism, could potentially create more problems, than it solves. Better to leave such devices operate outside of the bands that radar detectors have been designed to receive for decades. Fortunately for us, Audi wisely uses an ACC system which utilizes a frequency well beyond that at 76.5Ghz.

It appears that the system only performs its function when the vehicle is traveling in excess of 35mph, however, we found that even when the vehicle was parked, the system emitted radar and even though the sensitivity of the system is designed to cover a range of fewer than 200 hundred feet behind the vehicle, it's emissions can be picked up by top-performing radar detectors much farther than that.

I can only hope that the engineers of such systems refrain from using K-band (centered at 24.1Ghz) to perform it's function. A lot of drivers of such vehicles from Audi, BMW, or Porsche routinely use one of these high-end radar detectors in their vehicles and it would be a total mess, if this system's use were to compromise the ability of these drivers to do so.

We will attempt to research this further and inform them of these issues, to see if an alternate series of radar bands could be utilized -- to stay out of the way of all the thousands, if not millions of radar detectors that are used throughout the world.

So for now, my recommendation is to either utilize the V1 with J-disabled, the STi Driver, or quite possibly the new 9500i as these detectors appear most resistant to falsing with these systems.

For others who use other detectors, or who choose to leave the V1 in its default setting, be prepared for this type of false. It is definitely different from any other false you will have likely experienced previously, so I hope our description here will serve to prepare you for it so you won't be alarmed, as we initially were, and so you won't over react and brake abruptly, particularly if you are ever passed by an Audi Q7 SUV with it's side-assist system activated.

My recommendation for existing owners of Audi Q7s which have this feature, please share this information with your local Audi dealer, so that they can consider the practical implications of incorporating these developing technologies -- which are based on radar or lidar -- into their vehicles.

I would like to extend a heartfelt thanks to the car guys of Don Rosen Imports (Alex, Greg, Tarik) who contributed and helped make this ground-breaking field-report as thorough and illuminating as possible. While they more than graciously lent a hand and a driver/vehicle, they sacrificed a good number of hours, across two days, in doing so. It turns out that Alex drives with an Escort 8500 X50 and Tarik with a V1 and were as interested as I was in learning as much as we could about this new technology that Audi has incorporated into their Q7. If any of you are considering a purchase of an Audi/Porsche in the near future, please show your appreciation and give Alex a call at 800.814.0681 or visit their showroom in person or online at http://www.donrosenimports.com/ If you mention this article, he'll be pleased to learn that they helped another enthusiast driver, like himself, and will personally see to it that you'll receive the attention and care that you deserve. Alex informed me that he can make arrangements for vehicle delivery to individuals who live out of the area, as well.

Finally, I would be remiss, for not crediting Mr. Valentine and his engineering staff of Valentine Research for being entirely candid with me -- by sharing some information that may not have been widely known in our industry -- about the true reason for the V1's superior sensitivity to this phenomenon.

I sincerely hope that something good will come out of this field-research and shared knowledge for all parties involved, especially Audi [and any other manufacturer considering implementing 24 Ghz ACC/ADAS/LDWS [or even 904nm infra-red] technologies into their vehicles]. And please, remember, what industry sounded the alert.

We'll be keeping a close eye on this one as we've been in the process of bringing the potential of this issue to the attention of the major automotive manufacturers -- who purchase these systems from the automotive electronic manufacturers -- as well as the manufacturers of these devices. We'll post follow-ups at the appropriate times.

Veil Guy

Additional Related Reading: