fais2000

With all the garbage you hear, it is hard to see if there is something out there that actually works. I saw this advertisement for a device called the PHAZAR that supposedly jams radar by throwing a FM signal along with the radar. I dunno?! The thing that strikes me is that it is in automobile magazine, page 145. Please if anybody has any insight on this, I would love to know. If this actually works, i think my dreams would be answered. The price for this piece is about $200. It is advertised by a company called Technoscout. They dont have this on there website, but they do have another item called the prowler that is something like it that sells for $795, but doesnt really sound as good as this "device". The url is below. Anyway, any advice?
http://www.comtrad.com/cfusion/templ...343&sourceid=0

regards
fas

Parkerfe

Those jamming devices are all a joke. I have read test im auto magazines that all confirm they don't work. Get a Valentine 1 Radar/lazer detector and pay attention.



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fais2000

park i think you are probably correct. But I would love to test one of these things out, even though it is probably a waste. I would be willing to buy one if somebody around the NY/NJ area would have access to a radar/laser.

fas

Roton

Jamming a laser range/rate detector would probably be out of the question for that kind of money and product available market served. Frequency modulating a signal to jam
Terahertz light frequencies with a radar carrier frequency of 10's of Gigahertz ain't gonna do it.

Now if you want to not only jam, but tell the police radar what speed you want them to read, that's relatively simple. A technique I used many years ago is called Baseband jamming. While I used it on X Band radar (10.525 GHz.), it is easily scalable to the higher frequency bands now in use.

What radars do is broadcast a pure signal out at relatively low power (10's to 100's of mW) and some small fraction of the signal that bounces off of your car is then recieved by the radar unit shifted in frequency by an amount proportional to the speed you're going. At X Band, this Doppler shift was 31.4 Hz/MPH at 10.525 GHz. To get the difference, a small portion of the tramsmitted signal is diverted inside the unit and the mixed with the recieved, frequency shifted signal. The output of this mixer would then provide the sum and difference signals. The lower frequency, difference signal would be the 31.4 Hz/MPH. As an example, 100MPH would yield a mixer output frequency of 3140 Hz. This is easily converted, being in the same range as audio, to read out MPH by simply dividing by 31.4 in this case.

The jammer I designed took advantage of a given fact (take my word on this one) that the radar's mixer will output the sum and difference of two input signals in the face of pure un-amplitude modulated signals. If we were to provide a radar signal in the same relative power range and relatively close (no need to be exactly on his 10.525 GHz carrier, the front ends of these things are crude)to his frequency,and amplitude modulate (turn on and off the signal) at a rate of 3140 Hz in this example, he'd read not the difference in frequency between his transmitted signal and the reflected signal (very, very faint as most of it is reflected all over the place, not back into his antenna), but the much more powerful signal that your pointed straight at him with. What will then happen in his mixer is that it will then act like what is called an AM detector and output only the 3140 Hz that you are sending him. The difference frequency that he thinks he's looking at will be completely overridden by the amplitude modulated signal that you're nailing him with at thousands of times the signal amplitude that his reflected signal is coming back.
Conveniently, there just happens to be an Amateur Radio band near where you want to be at 10.250 GHz. which will work just fine. (Sorry officer, but I was just trying to work some X Band traffic for the VHF contest).

So you're in your M5 doing 150 MPH and this cop looks at his radar that shows 55 MPH (or whatever you decide to set your jammer speed at). In another scenario, you're sitting up on an overpass at a specific time that you know a particularly arrogant guy in an E55 is getting out of work, going the speed limit and on the other side of the overpass is a speed trap. You program your trusty jammer to output the equivalent of 150 MPH and the rest is history.

For a more "permanent" solution, get a hold of a piezo electric crystal material sometimes used in sonar applications. It's called Lead Zirconium Titinate. When shock excited it produces an extremely high amplitude pulse as it is destroyed. The frequency of this pulse is determined by the size of the cavity it is mounted in. So you have a machinist mill you out a cavity in a block of aluminum whose dimensions correspond to the frequency of the radar you want to jam. Next get a hold of a 22 caliber starter's pistol and machine the barrel to screw into this block. The opposite end of the block is open and you simple place a small 1/2" square piece of this crystal maybe 1/8" thick in the cavity, then put a piece of masking tape over the square hole so it won't fall out. Screw a small horn type antenna on the front of the block, load the pistol with a 22 blank cartridge, aim and fire. 100+ Megawatts for a couple of microseconds will render any radar's mixer diodes permanently kaput instantly within a range of 200 yards.
Of course the sound of a gun going off 200 yards from a cop might result in a jail term or returned fire, but at least he won't be using that radar for awhile.

Honestly folks, these two methods really do work, but like anything else, common sense in their application (or not) is key.

Regards,
Doug

bobafett

damn Roton, it's so simple!

Now where were you 6 months ago when I was seriously considering it? Correct me if I'm wrong, but radar jamming is illegal nation-wide (or maybe it's just here in CA). I know that laser jammers are ok, but CHP doesn't use lidar in the first place.

--Dan

Yupkwondo

Roton, could you please E-mail me with some contact info, I have some questions for you.


Yupkwondo@aol.com

Eric

Thanks for the great write up Doug, any tips on how to get our hands one?

Eric

Roton

As far as the availability of the jammer, to my knowlege none have ever been really on the market. The ones that I built back in the early 80's, I did from scratch. Basically, the only part that's not available from standard sources is the microwave transmitter itself, but I believe you can easily get them today from any number of sources listed in Amateur Radio magazines. The unit is called a Gunn Oscillator (the word Gunn is the name of the guy who discovered the principles involved in the workings of the Gunn diode used in this ocillator), and most of these units were made by a company called MaCom in Burlington, MA. I believe they were distributed by a company called Whitehouse, Inc. Gunn Oscillators were available in both X and K Band variants. They are small (X Band unit had a waveguide flange about 2"X2" and was about 1.5 inches deep, the K Band unit was slightly smaller). Small 10 dB gain horns were also sold for them. I believe back then that they sold for something in the neighborhood of about $100.00 each.

The X Band unit is powered by 10 Volts, the K Band I think was about 7.5 Volts. When you power then up, the oscillators put out their respective frequencies. Each has a small piston type mechanical tuner that lets you adjust their frequency. As I said before, this isn't critical as police radars have very broadband front ends. If you merely turn on and off the oscillator at different frequencies, you will transmit the required AM signal. So what you put in front of the oscillator is a pulse generator that you can adjust from say 314 Hz (10 MPH at X Band) to 3140 Hz (100 MPH at X Band). By building a simple audio frequency synthesizer, you could even have it readout what speed you programmed rather than having to convert frequency to doppler shift in your head.

Well, I'm on my way out the door to Arizona so I'll catch you all later.

Regards,
Doug

MarkM5Lauderdale

So Roton, I guess what he's saying is, "You wanna build some of those again for a select clientel?"
Dude, I'm in!
Mark

fais2000

oooh oooooh oooooh oooooooh oooooooooh

i want one too.

fas

Eric