I would like to know what the simplest method is to rendering a radar detector invisible to a radar detector detector. Is there a material I can use to encase my detector to accomplish this? Or must I open up the unit and apply RF shielding where needed? Wikipedia has a good step by step but I'm not technically competent to install the articles described, I should say knowledgeable to know what's what once I get in there. Thanks anyone?
That was the case maybe 15 to 20 years ago. The passive diode detectors did a good job of detecting other sources of RF energy as well as police radar. Mine did an excellent job of sniffing out a TDMA cell phone as far as half a mile away. iDEN and GSM phones are TDMA, and they were very popular back then, so the second generation superhetrodyne radar detector was created. Today there are radar detectors with fancy DSP signal processors to filter out non radar signals.
All superhet receivers have a local oscillator which DOES emit a minute, but detectable RF signal. A competent RF designer can minimize this RF leakage, a MUST do so for any device requiring FCC approval. Are all radar detectors designed to meet FCC emission specs? I doubt it. Could you do much to improve a leaky detector without a spectrum analyzer? Again, I doubt it.
Can a sensitive receiver pick up a detector whose RF emission is within the legal limit? Yes, at relatively close range.
So, in short, without some RF knowledge, and some specialized RF test equipment that operates at 10, 24 and 33 GHz, you aren't likely to hide your detector from the detector detector. Most police are using laser now anyway. Many detectors claim to be able to detect laser. They can....at the same time you are clocked, since the laser picks out one car at a time.
en.wikipedia.org/wiki/LIDAR_speed_gun
Well I would apply the procedures outlined here but first I have to be able to identify the parts. What does the local oscillator look like?
The local oscillator (LO) is the name given to a circuit made from one or more electrical components just like a VAS(voltage amplifying stage) or driver circuit in an audio amplifier.
There may be a separate LO for each radar band since they are quite different in frequency. It is also possible to use one oscillator for all bands by using harmonics of the main oscillator signal.
In modern RF design these components would almost certainly be SMD. At these frequencies, leadless SMD, since lead inductances are prohibitive. There will be an active device, possibly a few passives (L's, R's and C's) although they may be integrated inside the active device, and some type of resonator.
The resonator in the 10+ GHz range is often a DRO. This is a short length of strip on the PC board coupled to a tiny "hockey puck" of ceramic material mounted to the board. If this is the case, the entire assembly will be housed inside a resonant cavity, whose physical dimensions affect its operational frequency. The cavity is often formed with a metal can soldered to the PC board. The active components are inside the can. Attempting to remove the can and add absorptive material inside it will at best alter its operational frequency, and probably cause it to cease oscillation. My luck tweaking the oscillators in 10 to 12 GHz satellite LNB's is near zero.....and I had access to all the fancy equipment in a Motorola lab.
The LO generates a signal for the MIXER. The mixer is another circuit that mixes the incoming radar signal with the LO to create a new signal that is more easily amplified and detected. This new signal is called the Intermediate Frequency, or IF. Mixers, by definition are NON LINEAR devices. They create HARMONICS (technically harmonic distortion of the LO signal) in normal operation. The mixer has three ports, the RF (radio or radar frequency input) and the previously mentioned LO and IF ports. Ideally signal comes into the RF port, mixes with LO applied to the LO port, creating IF that comes out of the IF port. Mixers are one of the most imperfect of all RF devices, a signal applied to any port will leak out of any other port. This means that some of that LO signal and its harmonics will leak back out the RF port. This is a well known issue with ALL superhetrodyne radio receivers including radar detectors.
The simplest superhetrodyne receiver simply attaches the antenna to the RF input of the mixer, thus creating a path for the LO leakage to escape back out of the antenna and be transmitted by it out into the air.
Most antennas work equally well as a transmitting antenna as they do as a receiving antenna. This path is BY FAR the MOST DOMINANT leakage source of the LO signal from a simple radio receiver, and the hardest to cure. In the case of a radar detector, you are pointing that antenna DIRECTLY at the COP CAR! Blocking or suppressing this leakage, will also block the radar signal you are trying to detect.
There are means to reduce this mixer leakage, but all involve changes at the circuit design level, and they are costly at the GHz frequencies involved here. A microwave circulator or an RF amplifier stage could be added between the mixer and the antenna. Either would reduce the LO leakage by 10 db or more if properly designed and implemented. Neither are simple, or particularly effective above 10 GHz, nor could be implemented after the design was done.
I don't know anything about the detector you have, or anything about the modern high $$$ stealth detectors, but a detector costing several hundred dollars could have been designed in this manner. In either case making improvements in the LO leakage without specific microwave receiver knowledge and a RF spectrum analyzer good to 30+ GHz are highly unlikely without severely impacting the detectors performance.
The FCC regulates how much RF energy can legally leak from any product sold in the US that contains an oscillator, including microprocessor clocks. All such products are supposed to be subjected to testing, and the results submitted to the FCC before the device is sold.
There are legal limits depending on the frequency as to how much RF energy can leak into the air from the device, and be conducted through any wire or connector on the device including the power cord. These limits are meant to avoid interference with radio, TV, aircraft, and other intentional radio communications.
The standard are pretty lax at frequencies above 10 GHz where radar operates, since interference is not usually a problem. A properly designed radar detector that MEETS FCC SPECS can still emit enough RF energy to be detected by a purpose built detector detector at a considerable distance!
Granted, despite the poor grammar, the article you linked does point out several means that a manufacturer would use to reduce the RF emission of a microwave product during the design cycle.
I read a test report in a magazine a few years ago that stated that the best defense against LIDAR (laser) is a dirty black car, and a state that does not require front license plates. As stated in the article, this can be tested with a laser pointer.
Radar range is most influenced by the surface that the radar beam bounces off of. Most cars mount the radiator vertically, and this is the predominant radar reflecting surface. The Corvette mounts the radiator at an angle to lower the hood line, and in another magazine test, the Corvette had the shortest detection distance, while full size pickup truck were worse case.
I have heard of making your car more invisible to radar by installing microwave absorbing foam inside the plastic on the front of your car, but that stuff degrades pretty quickly in high temperatures.......
Wow. Thank you for that insight. Okay, is there more than one way to skin this cat? What if I were to mount tuned, vibrating baffles in front of those surfaces susceptible to detection? A license plate on a base that moves it rapidly back and forth?
I have heard that people have successfully done this, but I would imagine that success depends on a lot of different things, some of which can't be controlled.
A good coating of fresh West Virginia mud works good for laser....probably why radar is still used here. WV does not have front plates, but visitors from Ohio do. Ohio is 2 miles away.
Lidar uses a narrow beam that is small enough to be aimed through a gun like sight at a specific part of a car. It uses light which is reflected from the SURFACE of an object. This must be a surface that will reflect the light back toward the cop. As stated this is usually the front license plate, headlights, an emblem or other shiny part on the front of the vehicle. Ford and Dodge Pickup trucks with the shiny chrome inserts in the grill are easy targets. You can test your car with a laser pointer at dusk to see which parts of the car will reflect the most light back to you when you are standing in front of the car a few hundred feet away. Anything that can be done to reduce the reflections will reduce the effective range of the Lidar. If you are in a state or province that requires a front license plate, often a few washers under the mounting screws an change the angle of the plate so it reflects the light downward (or upward) rather than right back to the Lidar.
Radar uses a beam that typically covers the whole car, and often surrounding cars in radio waves. The waves can only be reflected by metal or metalized plastic (truck grills, headlight reflectors) that is nearly vertical. The waves pass through plastic as if it wasn't there. Open the hood of your car, and look at the radiator and its metal support structure that is behind the plastic grill. This is the primary target for a radar gun. You can't see the radio waves, but the same principles apply. You want to reflect these waves at an angle instead of back to the radar gun. Old X band radar (10.5 GHz) could be bounced with 1/4 inch hardware cloth, but X band is rarely used any more. Ka and Ku band (24 and 33 GHz) require nearly solid metal, even aluminum window screen can be penetrated. If the plastic in front of the radiator and its support is NOT vertical ordinary aluminum foil from the kitchen that has been wrinkled , then somewhat flattened out, will make a random reflector, at least partially reducing the reflections.
It might be counterintuitive, but it's probably easier to make the front of a car LIDAR stealthy than RADAR stealthy.
The best way to do both is to look for inspiration at the masters in the field:
-him
-and him
The first one shows us the easiest way: just make sure that the front of your car consists of plane surfaces that point laterally and not towards the forward direction.
For LIDAR, the surfaces can be either very good reflectors or very good light absorbers. For optical frequencies, both are very easy to achieve:
-reflectors: any reasonable good mirror
-absorbers: many, for example a fine grained black sponge, etc..
The same principle holds for RADAR: very good reflectors or very good absorbers. The problem is, for microwaves, they both are difficult to come by.
The two examples cited above achieve that goal, but the cost of copying their solutions for your car is, I'm afraid, quite high (to put it mildly).
The best way to do both is to look for inspiration at the masters in the field:
-him
-and him
The first one shows us the easiest way: just make sure that the front of your car consists of plane surfaces that point laterally and not towards the forward direction.
For LIDAR, the surfaces can be either very good reflectors or very good light absorbers. For optical frequencies, both are very easy to achieve:
-reflectors: any reasonable good mirror
-absorbers: many, for example a fine grained black sponge, etc..
The same principle holds for RADAR: very good reflectors or very good absorbers. The problem is, for microwaves, they both are difficult to come by.
The two examples cited above achieve that goal, but the cost of copying their solutions for your car is, I'm afraid, quite high (to put it mildly).
No one mentioned that there is another way to fool a RADAR or LIDAR: active jamming.
Obviously, this method is not stealthy.
Also, it's much more difficult to implement for a regular person.
Obviously, this method is not stealthy.
Also, it's much more difficult to implement for a regular person.
Wasn't my suggestion to install rapidly moving baffles a form of jamming?
btw, those links are exactly what comes to mind
Waze is free and if you just drive near the speed limit (here in MI State Police will ignore you at 80 in a 70) life is simple!
Come to think of it, I remember short chains extending from the underside of a vehicle being outlawed here in Canada and rubber straps substituted for the purpose of discharging static from a vehicle back in the 70's. Any connection?
Haven't you ever been out on a limb? A hippie? A rebel? Anti-establishment? Immature??
80 in a 70? That's like 130 in a 110 here..'20' over. You guys got it good. Here they let you get away with 10km over which is about 6.2mph. You spend the whole time staring at your speedometer.
I had an 84 mile per day commute for about 2 years in Florida on I-95 back in the early 90's. I had an old 4 cylinder Dodge that I could drive the entire trip on the interstate with the accelerator held to the floor, usually in the right lane. Top speed was anywhere from 75 MPH (convertible top down) to 90 MPH (top up, good gas, cold day, tailwind, downhill). There were always plenty of BMW's and Mercedes going 90+ for the cops to chase. Holding the pedal down for 45 minutes at a time eventually popped the head gasket....twice. I got a minivan. You can speed right past the kid in the loud Mustang in a minivan. He will get your ticket!
I didn't mention it, because it is illegal, and a felony in some states. Hypothetically it's within the reach of most DIYers to build a LIDAR cloaking device, and I know it is possible to build an RF cloaking device, I built and tested one. The concept is similar for both devices.
Lidar, and radar rely on sending a pulse of RF or light energy through the air, bouncing it off of a moving car, such that enough energy is returned to ACHIEVE A SUITABLE SIGNAL TO NOISE RATIO such that frequency (radar) or timing (Lidar) information can be recovered to calculate the car's speed.
Most "stealth" systems concentrate on lowering the energy that is returned by the car toward the radar or lidar's receiving antenna such that it is below the systems noise floor. The obvious other side of this equation is to RAISE the NOISE FLOOR of the system. Both together is the best approach.
Some active "jammers" attempt to confuse the system by generating pulses of energy (RF, light, or both) at specific intervals that are known to cause errors in popular radar or lidar devices. This is the wrong approach, and is easily detectable.
We should know that one noisy tube or transistor in an audio system can make the whole system noisy. Where is the worse place to put that noisy tube? In the phono stage where the wanted signal is the weakest. So we want to inject noise at the receiver input (radar or lidar gun).
Lidar is the easiest case. The system uses a specific frequency laser. LED's are available on this frequency, so why couldn't we just line the entire front surface of our car with LED's? Well, this may swamp out the return pulses under some conditions, but would be akin to a huge DC offset in an audio amp.....but this amp has a DSP that will compensate for the offset (high levels of ambient light).
The system is by definition, fixed frequency, but the return pulses are varying in amplitude because the reflective surface (the car) is moving. What we need is to amplitude modulate the LED's with random noise. That's right we need to plug our noisy tube into the system that controls the brightness of the LED's. This could be done with a noisy current source feeding the LED string, but is probably best done digitally by clocking the LED's on and off with a pseudo random sequence. I have not attempted to build such a system.
Radar is a bit more complicated, but easier to confuse, since the system needs to recover the FREQUENCY of the incoming RF signal amidst the varying RF amplitude (because the car IS moving). The radar gun does not emit an RF signal of a constant frequency. Every radar gun will be on a slightly different frequency than the next one. The transmitter frequency will drift, and contains considerable jitter, simply because it is cheaper than a high quality source, and it doesn't matter in this application.
In the radar gun, the incoming signal is compared to the transmitter and the difference frequency (Doppler shift) is counted. In reality the transmitter IS the LO for the receiver, and the IF is counted!
To create the proper noise environment we must apply both AM and FM to an RF signal source to build our cloaking device. Some friends and I built such a device back in the 80's. We used a VCO for our signal source, and applied noise to the control voltage of the VCO for FM noise. The same noise signal was used to modulate an AM RF output stage to produce about half a watt of RF at 915 MHz. (902 to 928 MHz is an unregulated frequency band in North America, under half a watt, almost anything goes). That was applied to a passive diode multiplier made with 20 or so 1N914 switching diodes. This generated about 10 milliwatts in the 10 GHz region. We devised a home made horn antenna from PC board material.
We had access to a Kustom Signals MR-7 X band radar gun for testing. Our cloaking device worked pretty good. My 1982 Dodge Charger was detectible by the MR-7 for more than a half mile on open road with no other cars present. With the cloaking device operating this was reduced to about 100 feet, and the guy with the radar was standing directly in the street in front of me. No other stealth measures were applied to the car.
The results were not as dramatic when we tested with a 1975 Chevy pickup truck. This tank was detectable by the MR-7 for almost a mile, and a reliable speed reading was obtained from about 400 feet with the cloaking device engaged.
NOTE, The MR-7 was state of the art in the late 70's, but radar has evolved since then. I was transferred to a different Motorola plant in the late 80's and the cloaking device was lost. By then it had been modified for use in cell phone jamming. No further radar work was attempted.....since the only speeding ticket I ever got was in about 1980. The only detector I have ever owned was the passive Uniden that I took apart when it detected more cell phones than cops.
I got a 10 GHz RF door opener in a surplus auction. I noticed that it had a peculiar effect on the motorcycle cop that hunted speeders around the local elementary school. If I pulled into the McDonalds parking lot, set the thing on my dash, and turned it on, the cop would give up and leave the area within minutes. Coincidence???? I think not.
BTW, said 1982 Charger was capable of going 154 MPH (tested by me), and yes it was that car that got me the ticket....in a known speed trap, for 44 in a 35.
I didn't mention it, because it is illegal, and a felony in some states. Hypothetically it's within the reach of most DIYers to build a LIDAR cloaking device, and I know it is possible to build an RF cloaking device, I built and tested one. The concept is similar for both devices.
Lidar, and radar rely on sending a pulse of RF or light energy through the air, bouncing it off of a moving car, such that enough energy is returned to ACHIEVE A SUITABLE SIGNAL TO NOISE RATIO such that frequency (radar) or timing (Lidar) information can be recovered to calculate the car's speed.
Most "stealth" systems concentrate on lowering the energy that is returned by the car toward the radar or lidar's receiving antenna such that it is below the systems noise floor. The obvious other side of this equation is to RAISE the NOISE FLOOR of the system. Both together is the best approach.
Some active "jammers" attempt to confuse the system by generating pulses of energy (RF, light, or both) at specific intervals that are known to cause errors in popular radar or lidar devices. This is the wrong approach, and is easily detectable.
We should know that one noisy tube or transistor in an audio system can make the whole system noisy. Where is the worse place to put that noisy tube? In the phono stage where the wanted signal is the weakest. So we want to inject noise at the receiver input (radar or lidar gun).
Lidar is the easiest case. The system uses a specific frequency laser. LED's are available on this frequency, so why couldn't we just line the entire front surface of our car with LED's? Well, this may swamp out the return pulses under some conditions, but would be akin to a huge DC offset in an audio amp.....but this amp has a DSP that will compensate for the offset (high levels of ambient light).
The system is by definition, fixed frequency, but the return pulses are varying in amplitude because the reflective surface (the car) is moving. What we need is to amplitude modulate the LED's with random noise. That's right we need to plug our noisy tube into the system that controls the brightness of the LED's. This could be done with a noisy current source feeding the LED string, but is probably best done digitally by clocking the LED's on and off with a pseudo random sequence. I have not attempted to build such a system.
Radar is a bit more complicated, but easier to confuse, since the system needs to recover the FREQUENCY of the incoming RF signal amidst the varying RF amplitude (because the car IS moving). The radar gun does not emit an RF signal of a constant frequency. Every radar gun will be on a slightly different frequency than the next one. The transmitter frequency will drift, and contains considerable jitter, simply because it is cheaper than a high quality source, and it doesn't matter in this application.
In the radar gun, the incoming signal is compared to the transmitter and the difference frequency (Doppler shift) is counted. In reality the transmitter IS the LO for the receiver, and the IF is counted!
To create the proper noise environment we must apply both AM and FM to an RF signal source to build our cloaking device. Some friends and I built such a device back in the 80's. We used a VCO for our signal source, and applied noise to the control voltage of the VCO for FM noise. The same noise signal was used to modulate an AM RF output stage to produce about half a watt of RF at 915 MHz. (902 to 928 MHz is an unregulated frequency band in North America, under half a watt, almost anything goes). That was applied to a passive diode multiplier made with 20 or so 1N914 switching diodes. This generated about 10 milliwatts in the 10 GHz region. We devised a home made horn antenna from PC board material.
We had access to a Kustom Signals MR-7 X band radar gun for testing. Our cloaking device worked pretty good. My 1982 Dodge Charger was detectible by the MR-7 for more than a half mile on open road with no other cars present. With the cloaking device operating this was reduced to about 100 feet, and the guy with the radar was standing directly in the street in front of me. No other stealth measures were applied to the car.
The results were not as dramatic when we tested with a 1975 Chevy pickup truck. This tank was detectable by the MR-7 for almost a mile, and a reliable speed reading was obtained from about 400 feet with the cloaking device engaged.
NOTE, The MR-7 was state of the art in the late 70's, but radar has evolved since then. I was transferred to a different Motorola plant in the late 80's and the cloaking device was lost. By then it had been modified for use in cell phone jamming. No further radar work was attempted.....since the only speeding ticket I ever got was in about 1980. The only detector I have ever owned was the passive Uniden that I took apart when it detected more cell phones than cops.
I got a 10 GHz RF door opener in a surplus auction. I noticed that it had a peculiar effect on the motorcycle cop that hunted speeders around the local elementary school. If I pulled into the McDonalds parking lot, set the thing on my dash, and turned it on, the cop would give up and leave the area within minutes. Coincidence???? I think not.
BTW, said 1982 Charger was capable of going 154 MPH (tested by me), and yes it was that car that got me the ticket....in a known speed trap, for 44 in a 35.
Do you know if your speedometer is accurate? Changing your tire size from the oem recommendation can change your speedometer calibration, also most cars now have all electronic gauges and speed sensors that can malfunction i have seen it in a few cars.
Well I haven't climbed a tree in many decades so out on a limb isn't an issue for me. Hippie, etc. absolutely, but always employed so pseudo I guess. This issue is really simpler than your questions would imply. If speeding is motivated by time pressure/deadlines there is nothing that will blow your travel schedule like a 15 minute side of the road chat with an officer. Then there are the follow-on costs imposed by your insurance company. The secret to being on time is not how fast you drive so much as when you start out. Of course it helps to be retired with lots of time and very few deadlines!😀
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