Countermeasures
Countermeasures
One of the first attempts to fool traffic radar was to hang reflective objects on a vehicle; these included dangling loose chains, putting foil or steel marbles in hubcaps and securing strips of foil to the radio antenna. None of these counters did anything to fool traffic radar and, in fact, may have enhanced the target's radar cross-section (echo), enabling the radar to detect the target at longer range! Even so, drivers that used these techniques were subject to arrest in Rochester, New York, in 1953.
Today products exist that CLAIM to interfere with microwave traffic radar. Be especially skeptical of jammer claims, and in particular any passive jammers (all known passive jammers are useless). Some test indicate not only do these jammers not work, but they may enhance the target's radar cross-section (a jammer antenna, alone, tuned to microwave frequencies is a great reflector) enabling the radar to detect the target at longer range (10 to 30 percent in some cases!). Even so, drivers that use jammers are subject to FCC penalties (FCC public notice 1996). Also see Microwave Jammers below.
Some hood covers (bras) and license plate covers are suppose to absorb and/or disperse microwave radar energy thus reducing target radar cross-section and radar detection range. Any reduction is small with only a slight (if any) degradation in radar performance (maximum detection range).
Some license plate covers supposedly disperse laser light denying a laser radar target reflections from the license plate. However if the laser is not aimed at the (covered) license plate or the beam is wide enough to overlap other parts of the vehicle this method will fail. In fact most reports indicate license plate covers have little if any effect on laser (or microwave) radar performance.
False information has circulated on the Internet (mainly through Email in 2000 and 2001) concerning avoiding points against your driver's license due to a traffic ticket (speeding, red light running, etc.) issued in any U.S. state. Basically the scam message falsely claims by over paying a ticket by a few dollars (mail-in only), then not cashing a check for the difference when the system corrects the overpayment, prevents the system from assessing points against your driver's license (until the difference check is cashed) -- THIS IS NOT TRUE and DOES NOT WORK!
If one knows of or is warned (from a CB or a passing motorist flashing headlights) of an impending speed trap, it's a good idea to drop speed five mph below the posted limit. This may or may not prevent a ticket, but could help in court if a ticket is issued. If one can claim the vehicle speed was at least five mph below the limit, target speedometer accuracy will not be as questionable. It's not a bad idea to have the speedometer calibrated by a qualified shop, even after a ticket, so one may determine if the speedometer was accurate at the time of the alleged violation. If one has the speedometer calibrated be sure to retain all documentation for court evidence.
If a driver believes (such as a warning from a radar detector or a visual sighting) a traffic radar has just started illuminating and/or tracking the driver's vehicle; a good countermeasure is to gently decelerate (not a dead skid) about 3 or 4 mph per second (3 or 4 kmh per second). A traffic radar/ladar may experience problems measuring targets decelerating (or accelerating) because speed is changing too fast.
Some police switch on the radar only when the operator is ready to target a vehicle. Some radars transmit only long enough (tenths of to a second or more) to get a speed reading. With Across the Road radar (photo radar) a target is in the main beam for a short time (tenths to 2 seconds). Depending on the situation a driver may only have a fraction of a second to respond, and in some cases may not be warned at all until after the radar gets a measurement. The lesson: do not depend solely on a radar detector to warn a traffic radar is in the area.
Laser radars, ladars, have a narrow beam making it difficult to detect unless the laser is aimed directly at a laser detector (not just the vehicle). Laser radars could (under good conditions) measure target speed in about 1/3 of a second giving the target vehicle little or no time to react. A laser detector may sense a laser signal reflecting off another target or a stationary object, but this condition usually has a short duration if it occurs at all. Laser radar detectors are generally not as effected as microwave detectors.
If pulled over most officers prefer that you stay in your vehicle. When the officer approaches be polite and keep your hands visible -- at night turn on your interior doom light before the officer approaches. If ticketed collect as much information as possible about the circumstances. Besides information on the ticket some or all of the ADDITIONAL DATA below may be helpful when analyzing events later.
ADDITIONAL DATA SHEET
(1) RADAR/LIDAR Make & Model: ______________
- - - - - - - - - - - - -
MOVING RADAR Patrol Speed: ____ mph km/hr
Radar Angle to patrol car: ____ degrees
(2) Distance RADAR from Target Lane: ____ ft m
or lanes between Radar / Target: ____
(3) TRACKING Range/Time/Landmarks
Start: ____________________
End: ____________________
TOTAL: ____________________
(4) OTHER VEHICLES
near Radar and intended Target
______________________________
______________________________
______________________________
(5) OTHER TRANSMITTERS in the area
(note all patrol car antennas)
cellular UHF VHF HF CB
|
Common (poor) excuses* for speeding (don't use these).
Some radar detectors will identify a radar signal sooner than others, but the difference is usually not significant. If a traffic radar is continuously transmitting, a good detector can give a mile or two warning under ideal conditions. Bends in the road or objects that mask the radar signal will reduce radar detector performance as well as radar performance. Typically on average radar detectors require at least 150 milliseconds (150 ms = 0.15 seconds) to detect and identify a radar signal.
One can get the most from any given radar detector by proper installation -- the detector antenna should be clear of any obstructions (especially metal such as wiper arms) and mounted as high as possible. Some electrically heated windshields, such as the Ford Instaclear or General Motors (GM) Electriclear, have metal film coatings reflective to microwave signals. Not only do these windshields obstruct signals and prevent the use of a radar detector (or a radar), these windshields increase a vehicle's radar cross section (RCS) increasing radar detection range.
A large selection of traffic radar detectors is available with a variety of options. Some typical options are listed below, not all detectors have all functions.
SIGNALS DETECTED
RADARS NOT USED IN USA
RDD -- RADAR DETECTOR DETECTOR (also see below) RDD -- RADAR DETECTOR DETECTOR (also see below)
Some radar detectors, intended to defeat radar detector detectors (RDDs), built around the years 1999 to 2003 emit unintentional and unavoidable signals (specifically the LO -- Local Oscillator, see RDD's below) that can interfere and disrupt Very Small Satellite Terminals (VSATs). VSATs operate (downlink) between 11.7 - 12.2 GHz and are commonly used for credit card transactions at gas pumps, Muzak (music) systems in fast-food outlets, and financial transactions, among other business uses. In 2002 the Federal Communications Commission (FCC) restricted emissions of radar detectors in the VSAT band to a maximum of 500 µV/m at 3 meters1, effectively eliminating sales in the USA of radar detectors that have LO's in the VSAT band. Radar detector's sold in the USA after around 26 November 2003 must meet the stricter requirements.
1 -- First Report and Order (R&O), FCC 02-211, July 12, 2002
Also see Links to Other Sites for radar detector manufacturers.
Safety Warning System (SWS) option
In addition to detecting traffic radar signals, Safety Warning System (SWS) detectors (available since 1996, approved by the FCC on 1999 Jan 28, FCC Rules Part 90.103) are capable of receiving specific messages broadcast from special transmitters (fixed or mobile). Besides looking for traffic radar signals, SWS capable receivers also look for safety warning signals (once every 3 to 6 seconds). A special transmitter broadcast a coded signal (a safety message) intended for reception by motorist in the area. An SWS capable detector alerts the driver with an audio tone that a message has been received and displays the message (some detectors use a synthesized voice). Sixty-four short fixed text messages are possible, up to 2 different messages may be broadcast one after the other. Variable messages are allowed if none of the available fixed text messages is appropriate. Radar detectors that do not have the SWS feature will detect a SWS signal message as a K band radar.
Transmitters broadcast at 24.1 GHz in the (lower part of) traffic radar K band. Transmitters function in both mobile (emergency vehicles such as police fire or ambulance, slow and/or oversized vehicles, school buses) and stationary modes (construction areas, dangerous stretches of road, or area information). For some stationary transmitters the broadcast message can be programmed from a remote location via radio or phone link.
| SWS Transmitters | |
| Frequency | 24.100 GHz ± 50 MHz |
| Power (ERP) | 50 milliwatts (mW) |
| Beamwidth | 23 degrees (horizontal) |
Georgia Tech Research Institute (GTRI) developed the system specifications as part of the Smart-Highway plan. Safety Warning System, L.C. (941-473-1555) is an organization formed to develop and promote the system, and has donated transmitters to local and state governments and at least 3 countries (Russia, New Zealand, and the Netherlands) as of 1998.
Safety Alert option
Cobra Electronics Corp.
Safety Alert System, introduced in the 1990's, transmits 1 of 3 fixed messages (Emergency Vehicle -- Train -- Road Hazard) intended for reception by special receivers or radar detectors (designed to receive the Safety Alert signal). Radar detectors that do not have the Safety Alert feature will detect the signal message as a K band radar. The Safety Alert System transmits at 24.07 GHz, 24.11 GHz, and 24.19 GHz.
A radar detector detector (RDD) is used to enforce anti-detector laws by sensing signals that leak from a radar detector's local oscillator (LO); detecting a signal indicates a radar detector is operating (on) and near-by. All superheterodyne receivers have a local oscillator, and most if not all radar detectors use a superheterodyne receiver. Many (espically older models) radar detectors use a local oscillator that operates around 11.558 GHz. Some radar detectors have LO's that operate somewere between 12 - 15 GHz (intended to defeat RDD's).
A superheterodyne receiver coverts RF (radio frequency) signals to an intermediate frequency (IF) by mixing the RF signal with the LO signal (IF = RF ± LO). Mixers are not perfect and leak some (-35 to -50 dBm) of the LO signal to (and out) the antenna. Some radar detectors may have a pre-amp or isolator between the mixer and antenna that should reduce LO leakage, but may not eliminate it. The old (and unreliable) crystal radar detectors (X band) cannot be detected by radar detector detectors (RDDs) because the crystal radar detectors do not have a local oscillator.
Some mobile amateur radio transceivers leak signals in the X band that can set off an RDD. Several people operating legal ham radios were wrongfully accused of possessing radar detectors because their amateur radios were detected by an RDD. Microwave point-to-point communication systems operate in the band 10.7 to 13.25 GHz. These systems have the potential to register on a radar detector detector if the microwave transmit frequency is in or near the RDD receiver band (varies with RDD model).
RDD's use superheterodyne receivers and have some LO leakage. Some radar detectors are designed to detect this leakage and shut down.
Radar Detector Detector (RDD) Models
Also see Links to Other Sites / RDD Manufacturers
From time to time traffic radar jammers appear in magazine ads and such (the Internet). Be aware MOST, if not ALL, of these jammers are useless (absolutely no effect at any range under any conditions) based on test reports by Automobile magazine, Car and Driver, RADAR Reporter and Truckers News. The legality of jammers is also in question and somewhat up to the whims of bureaucrats and politicians (local, state, and federal) regarding enforcement and court interpretation of the law. Several U.S. states and some countries prohibit the use or possession of a jammer.
For the United States FCC (Federal Communications Commission) to consider an intentional radiator legal the field intensity (power) must meet FCC limits (Rules Part 15) AND the device must perform some function for the public good. Traffic radar jammers are not considered good for the public by the FCC.
The FCC considers the use of traffic radar jammers as malicious interference and strictly prohibited by the Communications Act of 1934, as amended, as well as by FCC rules. Anyone using a jammer risks such penalties as losing FCC licenses, paying a fine, or facing criminal prosecution (from FCC Public Notice -- FCC Regulates Radar Transmitters, but not Radar Detectors, DA 96-2040, 1996 DEC 9) .
Passive jammers are suppose to re-radiate the radar signal after distorting it (adding noise and/or rapidly shifting frequency) in such a way the true target reflection is masked by the distorted signal. A passive jammer does not generate or amplify a signal, only channel or redirect the radar signal (after distorting) back toward the radar. For this method to work the jammer (distorted signal) power must be as large as or greater than target reflected power -- the jammer antenna would need to capture well over half of all the radar energy striking the target (a very large jammer antenna), and be aligned to the radar antenna. To date all known passive jammers have absolutely no effect on any radar under any circumstances.
On 4 December 1997 the FCC ruled passive jammers violate federal regulations because the jammers radiate RF (Radio Frequency) energy that (or is intended to) adversely affect the ability of law enforcement officials to protect public safety on the highways. The ruling was based on a passive jammer (Sprint II) made by Rocky Mountain Radar in Colorado. Before this ruling passive jammers were not considered transmitters and thus not covered by FCC regulations.
Active jammers either detect a radar signal before transmitting (jammer must have fast reaction time), or continuously transmit whether a radar signal is present or not (less sophisticated jammers). Many traffic radars can detect jamming signals (alerting the radar operator) even when the radar is not transmitting, this is why a jammer should only transmit when a radar signal is present.
A variety of jamming signals, depending on jammer, are used to blind (noise jamming) or fool (deception jamming) traffic radar. Transmitting brute force noise is one technique used to obscure target echoes; however this may be detected by many radars as a jammer signal alerting the operator. Another technique is to transmit a signal (fake target echo) at a frequency that will get into the radar Doppler discriminators/filters. The signal appears to the radar as a legitimate target overriding the real target echo; then the jammer signal will drift in frequency slow enough for the radar to track and too fast/erratic for the radar to calculate speed (effectively blinding the radar with no indication to the operator). The jammer signal could also force the radar to a set predetermined frequency that causes the radar to read a speed (set by the jammer). These last two techniques depend on knowing the EXACT frequency transmitted by the radar and generating exact (very tight tolerance) frequencies for transmission.
A relatively easy way to jam a traffic radar is to transmit an amplitude modulated (AM) signal modulated (anything from a square wave to a sine wave) at a rate equal to the Doppler shift frequency (varies with X, K, or Ka frequency -- see appendix C -- Doppler Equations) of the speed to be induced on the radar display. This method does not require knowing or transmitting the exact operating frequency for radar's that transmit at X or K band, the jammer only has to transmit in the radar band with the proper modulation rate. Because Ka radars can operate on multiple channels, the jammer needs to know the radar transmit frequency within about +/-100 MHz using this method.
Most traffic radars have some ECCM (Electronic Counter-Countermeasures) capabilities for detecting, alerting the operator, and countering Radio Frequency Interference (RFI) and jamming signals. The degree of success a radar has detecting and countering an unwanted signal varies with unwanted signal parameters, range between transmitter and radar, and radar make and model.
To date only one known (active) jammer actually works; the Stealth/VRCD made by Stealth Technologies in Naperville, Illinois -- reported (June 1998) to be out of business due to an FCC crackdown on radar jammer manufacturers. This jammer counters X and K band traffic radars; some later models reportedly also counter Ka band (fixed frequency) radars. The unit has an audio alert and LED to indicate when a radar is detected, and another LED to indicate the jammer is transmitting. The unit reportedly uses a fake target echo to blind the radar (as described in the above paragraph). This jammer received high marks from Car and Driver magazine, RADAR Reporter, and Truckers News. The RADAR Reporter (1993 NOV edition) tested the Stealth/VRCD against 5 different radars; 4 out of 5 radars could not register target speed at all. In all cases the radars gave no indication a jamming signal was present. The Decatur MV-715 (X band) managed to measure target speed (burn-through the jamming) on one test run, at a mere 150 foot range (will vary with target radar cross section). The jammer managed to detect and defeat the traffic radar in plenty of time and long enough for a driver to react (if necessary).
Also see Mutual Interference in chapter 5.5 -- RF Interference.
Many laser jammers are built into the front and/or rear license plate frame or attach to the license plate mounts, some mount to the front grill, bumper or other location. Some laser jammers transmit all the time, some only when a laser radar is detected (some of these alert the driver a laser detected, some do not). Some laser jammers transmit a fixed pulse width at a fixed rate (all known systems using this method are useless), some jammers match the laser radar pulse rate and/or pulse width. Because laser radars have such narrow beams a laser radar at close range (by not illuminating jammer receive aperture) could easily track a target without the detector ever alerting the jammer or driver.
The laser jammer beam must be relatively wide (10's of degrees) compared to the laser radar (about 0.2°); the wider the beam the more area covered and the more power required. If the jammer depends on masking (instead of fooling) valid target reflections (pulses), even more power is required. Many laser radars are designed to detect this type of brute force jamming and alert the operator.
EFFECTIVENESS
In 2002 several members of the National Motorists Association (NMA) tested 3 laser radar jammers in 3 different vehicles (Ford Contour, Audi S4, and Ford Expedition SUV) against an LTI UltraLyte 100LR laser radar (purchased in 2000). Base line tests (no jammer) showed the laser radar took a second or more to track targets at long range (about 2,500 feet), and usually (90% of the time) 0.4 seconds for targets less than 1000 feet.
Jammer: K40 Defuser -- Blinder M-06
out of production-- Blinder M-10 Approx Cost: $200 $50 used $300 Physical Style: license frame 2 modules 2 modules Operation: constantly
transmitsconstantly
transmitstransmits when
laser detectedWaveform: IR pulses at
fixed rate/widthIR pulses at
fixed rate/widthIR pulses at
rate/width of ladarSet off Laser
Radar Jam Alert:sometimes sometimes never Effectiveness: none none somewhat* * The Blinder M-10 was ineffective at ranges less than about 500 for all 3 test targets, and generally effective for the cars at greater ranges. For the SUV the M-10 was effective about 60% of the time for ranges between 500 and 1000 feet, and 90% effective for ranges greater than 1000 feet.
Source: National Motorists Association Foundation News, Nov/Dec 2002, Laser Jammer Testing.
Also see chapter 6.3 -- Laser Radar Operation / Detection Range.
Police Traffic Radar Handbook
Chapt 7.1 -- Countermeasures
