Buying a Radar Detector 11 bands ? What the hell ???l

wrote

bands

Well, hopefully, the highway has _some_ distance between it and the mall. Here in Californy, they put B-I-G parking lots between the stores and anything else. Well, unless it's a drive-thru. ;-)

"reckeless_homicidal_maniac_highway_terrorist_driver"

[snip]

tactics

some forces target 'naturally

Natch. They look for easy pickin's.

can it

transmitted

they are speaking.

Good analogy. Of course it doesn't work if two deaf people are 'talking' in sign language. (My analogy of the cops using laser or lidar guns).

handle

vicinity

motivation

question.)

ago.

interstates,

speeding

Most

is

this

need to

lambs who

them--but not

being if

probable

what

I've been following this thread for awhile, hoping to find just a hint of something electronic in it. So far, no luck. I was hoping someone would come up with some info on how those detectors work. Some schematics I've seen depict a simple cavity with a microwace detector diode in it, and a sensitive amp after the diode. Obviously this isn't very sensitive because the diode needs some substantial RF to make it conduct.

But I am pleased to see no BS about jammers. Like stuffing tinfoil into the hubcaps or other nonsense. The only jammer plans I remember seeing on the web consisted of a 555 timer chip driving the power input of a Gunnplexer. Maybe that's why all the cops have switched from X band to some other band. ;-)

a radar

carrier

condition and the

By "you extract", do you mean the cop? If you mean the detector, you can't extract the speed information if you don't have the reference frequency.

other than a

just a cop.

There are tons of motion sensing devices out there such as automatic door openers. They set off radar detectors like crazy.

[snip]

Police speed radar is really quite simple, transmit a CW signal, receive a return, mix the two together, the difference frequency is

2*Vcar/c*ftransmit = 2.086KHz at 70MPH (10GHz transmitter)

Then a uP converts the frequency to speed.

You can see by the above numbers that accurate jamming, like reporting a slower speed, is impossible using another oscillator... you're liable to report a higher speed (beat note).

One thing that does work is to smoke your brakes, decelerating very rapidly... you're not at a constant speed long enough for the uP to accurately count that small difference frequency.

I know this from experience... makes the cop **very** angry, so you're likely to get a ticket for something anyway ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Mfgrs will hold their secrets close to their vest because of competition. So, unless you're a specialist in microwaves or just that much more anal-retentive than most people, it really doesn't matter. How WELL it functions under real-world use is what people care about; not why.

Some jammers can work. However they aren't small, they are an active radar source, and they are controlled by the FCC in the US. Not a combination that lends itself to commercial ventures to the general public. What I want to do is import the UK cell phone jammer I saw a while back; create a moving "cone (dome) of silence" as you ride.

Not all of the detectors. Some are better able to filter out extraneous fluff.

--

Mark Johnson, Ft Worth; IBA#288; CM#1; EOB, DoD#2021; LPR#50
2003 FJR1300 "E²"; http://www.bikes-n-spikes.org

I've actually tested this on acceleration. With the right bike, you can light the afterburners and disappear from the radar screen. :-)

Traveling along and got a lock at 20, fired the loudness knob, the display showed 20 until I left off, suddenly the display jumped to 70.

The radar system can't get a verification (lock) that is close enough to the previous one, so the programmed logic tells the system that it's a false or inaccurate reading and doesn't update. You can do it braking too, but you have to really get aggressive and some bikes'll lock up the brakes when trying. To me it seemed much more controlled to do it under "thrusters". ;-)

I couldn't care less how they work at the electronics level. I only care

*how well* they work. This thread was cross-posted all over the map. Don't expect to see replies from only one NG. If the s.e.m folks wanted to reply, they were free to do so...

--
Mike Lynch
'04 FLHTCUI

ZX with ABS ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

I have never been able to find a proper answer. In the old days all door openers, burglar alarms, etc. were, exclusively, X band and K band was 'reserved' for police radar, etc. I assume that as the number of devices increased, the FCC allowed "civilian" use of the K band as well.

--

Surendar Jeyadev         jeyadev1@wrc.xerox.com
                         
                         Remove 1 for email address

It isn't the problem you think it is. While the RMS power output of the radar is very low (milliwatts), the peak effective radiatied power is actually quite high, probably kilowatts, so that the energy that hits the cavity for a microsecond even at distance of a mile or so is substantial.

as best I can tell, most of the radar detectors on the more expensive side do a digital signal processing analysis on the wave form and timing coming off the detector to determine whether it has the characteristics of radar (rep rate, ratio of on/off, and modulation). Some may have more than one tuned cavity as well.

In my University days we had a small search radar on the roof for training. It had an RMS output of 60 watts, the actual power into the antenna when it was on was 60Kw, (it fired for 1 microsecond every millisecond) and the antenna was sharp enough to push the Effective radiated power up past 1 Megawatt. It used to wipe out the computing center's mainframe at a distance of half a mile.

I guess Watson has me plonked, I've explained it twice now ;-)

[snip] Some [snip] [snip]

Police speed radar is **CW** (except for the instant-on trigger squeeze), and it is a homodyne (afraid of gays :)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

I've been looking seriously at a detector called the PNI "Sensoro Silver Bullet RX7500 / RX7600(compass)", which is supposed to be insanely small (1" H x 2.75" W x 3.75" L) and invisible to the VG2 (obviously) and Spectre I and II (III maybe?). Detector detector detectability is a concern to me for certain reasons, so that kinda piqued my interest. They go for about $100 US on ebay or 150 list.