Do radar detectors have blind spots?

[dcarver]

Read through TWN's latest performance award.. his Escort never triggered though moto Leo used radar. TWN stated the leo was to his left, behind him. I think I remember TWN's detector as being mounted on the right, on top of the brake master cylinder.

I've noticed that my detector is much more efficient to the front than the rear. The way that TWN got nabbed makes me wonder if the rider's body effectively blocks the reception of radar waves from the rear, especially if the radar source is located diagonally to the detector, making us much more succeptible to tickets from the 'blind side'.

Any merit to this theory?

 

[twowheelnut]

I would say, yes. :blink:

 

[ionbeam]

never triggered though moto Leo used radar

Just because LEO said so don't necessarily make it so. I've had several LEO's tell me they had me on radar when I know for a fact they didn't. On the other hand, some newer design radar guns are so fast that they can lock your speed before your radar detector can detect the signature. Could be what happened...
Escort's antennas aren't as good to the rear as the front. Rear and side detection varies between brand and model of detectors. Radar detector antennas aren't necessarily what you would think of as an antenna like rabbit ears or a roof antenna. In the gigahertz range of the radar gun it is actually a wave guide -- it is a tunnel with an opening size and pathway that only admits certain wave lengths or radar. The direction of the opening makes them sensitive to the direction of the incoming waves.

While the effectiveness of the radar detectors antenna varies from gun direction, the accuracy of the radar gun varies with direction also. If the gun is anything but 180° to the movement direction of the target there is cosign error in the speed reading. In fact when you are shot from the side, cosign error is a valid defense in court.

Your body is almost transparent to radar, as is the windshield in your car as long as it doesn't have an IR coating. The plastic on your motorcycle is essentially radar transparent. The radar detector mounted high up on the master reservoir is a good location.

 

[Mike-H]

never triggered though moto Leo used radar

Just because LEO said so don't necessarily make it so. I've had several LEO's tell me they had me on radar when I know for a fact they didn't. On the other hand, some newer design radar guns are so fast that they can lock your speed before your radar detector can detect the signature. Could be what happened...
Escort's antennas aren't as good to the rear as the front. Rear and side detection varies between brand and model of detectors. Radar detector antennas aren't necessarily what you would think of as an antenna like rabbit ears or a roof antenna. In the gigahertz range of the radar gun it is actually a wave guide -- it is a tunnel with an opening size and pathway that only admits certain wave lengths or radar. The direction of the opening makes them sensitive to the direction of the incoming waves.

While the effectiveness of the radar detectors antenna varies from gun direction, the accuracy of the radar gun varies with direction also. If the gun is anything but 180° to the movement direction of the target there is cosign error in the speed reading. In fact when you are shot from the side, cosign error is a valid defense in court.

Your body is almost transparent to radar, as is the windshield in your car as long as it doesn't have an IR coating. The plastic on your motorcycle is essentially radar transparent. The radar detector mounted high up on the master reservoir is a good location.

Does that include fillings & other metal replacement or enhancing body parts? :huh:

 

[TheAxeman]

I know you said that the radar gun had its green light on but couldn't that just mean that the gun is powered up and ready to go and not necessarily throwing a signal (i.e.-instant on)? I have my X-50 mounted on the right side on a ram mount, and although the detector definitely doesn't pick up a signal from the rear as easily as from the front, if there were cages in front of you that you were trying to get around the LEO's signal would have been bouncing off of those and the detector should have been screaming. I agree with ION that the LEO was probably BSing you to make you lose confidence in the thing. As for Carvers orignal question, I don't see how my fleshy, fatty body would be that much of a hinderance on the signal from a radar gun.

 

[ionbeam]

Does that include fillings & other metal replacement or enhancing body parts?

My, my, aren't we a clever group! You forgot to ask about the wires in heated clothing too. You would have to be really metal rich to totally block a radar signature. How's the iron level in your hemoglobin?

 

[twowheelnut]

Just because LEO said so don't necessarily make it so. I've had several LEO's tell me they had me on radar when I know for a fact they didn't. On the other hand, some newer design radar guns are so fast that they can lock your speed before your radar detector can detect the signature. Could be what happened...

He indeed had the radar on in it's holstered position as indicated by the little green power-on light. Too, when I fired back up and the Escort completed it's boot-up, it went nuts reading the ka band from his radar. He was still there, taking a radio call or sumpin' and hadn't touched his radar gun. Finally, I should note that he clocked me with his speedometer and not the radar. His only comment was that because his radar was on, even though holstered, the Escort shoulda alerted me of his presence. (Thanks for the rest of your post, though - things ya learn.)

Musta been that stealth Blue Coral Carnuba wax I just applied...

 

[Mike-H]

Does that include fillings & other metal replacement or enhancing body parts?

My, my, aren't we a clever group! You forgot to ask about the wires in heated clothing too. You would have to be really metal rich to totally block a radar signature. How's the iron level in your hemoglobin?

Not bad....all my replacement parts are stainless steel and or titanium.....(yes including the metal plate in my head twn).... :blink:

 

[RonBB]

In fact when you are shot from the side, cosign error is a valid defense in court.

Many years ago I did a bit of research with regard to Radar Detectors. During my research I learned that the cosine error has been used successfully in court when the patrol car is coming at you from the front and measures your speed. The reason this can sometimes be a problem is this: As the patrol car and the target vechicle approach each other the radar unit in the patol car is actually measuring two speeds. The first speed is the combined approach speed or the total of the target and the patrol car. The second speed measured is the "speed of the patrol car". It gets this speed from the background noise speed i.e. the reflections from signs, guard rails, etc. The radar unit then subtracts the "patrol car speed" which yields the "target speed". This is all well and good except if the patrol car speed has been obtained by say, a guard rail radar reflection which is at a considerable angle to the path of the patrol car the speed will read low, perhaps even significantly lower (Cosine speed). Then when the radar unit subtracts the lower cosine speed from the combined speed the target speed is shown more than it actually is. A smaller number from a total yields a larger number. While not an attorney I understand that this has been successfully used in court in some cases.

Didn't mean to hijack the thread it just seemed like a related bit of info.

 

[odot]

Maybe you kids should watch for leo's. And not depend on some little box to tell you that you are being tagged with radar.

 

[madmike2]

Maybe you kids should watch for leo's. And not depend on some little box to tell you that you are being tagged with radar.

Yeah, but that would entail adjusting the left make-up mirror so you could see over yonder on that side

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and then actually LOOKING in the left mirror.

"Oops! Sorry officer, I didn't see you driving up on my left." :dribble: :lol:

Jeez, Odot, there you go with your "low tech" solution, ruining all the fun! :lol:

 

[charismaticmegafauna]

Cosine speed change is readily evident when approaching stationary speed monitoring tailers set alongside roadways for road-users' edification -- if you maintain a constant speed, the indicated speed on the radar transceiver will decrease dramatically as you approach and the angle increases.

Detectors can also show non-use -- once, while speeding with a friend in VA (double scoff-law, detector&speed), we met an leo on-coming on a non-interstate 4-lane. He crossed over the median and as my friend and I pulled to the shoulder I said "No radar". I hid the detector and the leo asked both of us, "You boys were goin' kinda fast -- weren't ya?" We, of course, denied it and he let us go with a verbal warning. Lucky, sure -- but the RD was a help, too (leo had no proof).

 

[Charlie Hoss]

Read through TWN's latest performance award.. his Escort never triggered though moto Leo used radar. TWN stated the leo was to his left, behind him. I think I remember TWN's detector as being mounted on the right, on top of the brake master cylinder.I've noticed that my detector is much more efficient to the front than the rear. The way that TWN got nabbed makes me wonder if the rider's body effectively blocks the reception of radar waves from the rear, especially if the radar source is located diagonally to the detector, making us much more succeptible to tickets from the 'blind side'.

Any merit to this theory?

Those high tech answers were great...and right on! I currently use an older V1 which has excellent detection of rear radar signals. I previously used the early 2 band Passports which only had the front pointing antenna. The passport also did a very good job of detecting signals from the rear simply be picking up reflections coming back from the front. Most sensitive detectors will do this reliably. I don't value the sensitivity of the rear antenna on the V1 as much as the arrow which tells me the signal IS from the rear.

I agree that a radar signal is not impeded by the rider or any garments he may be wearing. Some "stealthy" riders mount the detector inside a fairing pocket or tank bag without any reception problems.

A detector's range is wildly variable. It all depends on "line of sight" to the gun. I once picked up a radar (K-band) signal at 5 miles with my old Passport. It was from a high spot on I-95. Some times you will only get 2 or 3 tenths of a mile warning on very curvey roads because you are only detecting weak reflections until you almost see the LEO.

Many (most) alerts I get are from refections, such as approaching a cop from the rear who is shooting to his front. He is no immediate danger to me but I still get a good alert. If the cop has the radar in a holster and not aimed in your direction, you will still get a decent alert if the radar is on.

All bets are off if the Laser (LIDAR) guns are being used. It is like light and the detector must have a clear view of the Laser beam.

The new BEE radar uses a new quick pulse called POP that most older detectors can't pick up. It sounds like there aren't many around yet and their accuracy has been questioned. Read all about it at www.valentine1.com.

Charlie

 

[JimV]

[Those high tech answers were great...and right on! I currently use an older V1 which has excellent detection of rear radar signals. I previously used the early 2 band Passports which only had the front pointing antenna. The passport also did a very good job of detecting signals from the rear simply be picking up reflections coming back from the front. Most sensitive detectors will do this reliably. I don't value the sensitivity of the rear antenna on the V1 as much as the arrow which tells me the signal IS from the rear.

All bets are off if the Laser (LIDAR) guns are being used. It is like light and the detector must have a clear view of the Laser beam.

The new BEE radar uses a new quick pulse called POP that most older detectors can't pick up. It sounds like there aren't many around yet and their accuracy has been questioned. Read all about it at www.valentine1.com.ions, such as approaching a cop from the rear who is shooting to his fro

Charlie

As Charlie points out, the Valentine One is the ONLY radar detector with two antennas [antennae?], one facing the front and one facing the rear. They apparently patented this feature which is why no one else does it. This is also the basis of the directional arrow system and the reason that they are the only ones with directional arrows that presumably work based on the relative signal strengths of the emitter as received on each antenna. Since all non-V1 detectors rely on reflections to detect emitters to the rear, the V1 probably has a significant advantage in areas like the desert where other vehicles are the only things for the radar to reflect off of. However, if you are already going significantly over the speed limit, it is unlikely that the LEO would be able to sneak up on you an zap you from the rear. I see them playing the stalking from the rear game all the time here. It works great if you're going 10 over and the cop is going 15 over so he can stalk you from the rear.

As I understand it, Valentine was actually late to the game with POP mode and got hammered in several independent reviews before adding it which is why it is so prominently featured on their website. Also as I understand it, due to inaccuracy, POP mode is only supposed to be used to see if you're speeding so that they can use the regular mode on you to issue a ticket. It would be interesting to see if anyone has gotten a ticket tossed based on the fact that their radar detector said that the cop used POP mode but not the regular mode.