TRAFFIC RADAR HANDBOOK
2002 EDITIONs
ISBN: 0 7596 8832 8 (hardcover)
ISBN: 0 7596 8832 X (paperback)

Print version
Addendums / Revisions

Outline
• chapter 1.1 -- Police Traffic Radars / X band and Ku band
• chapter 1.2 -- Other Speed Measuring Systems / Distance / Time ERRORs
• chapter 5.4 -- Operational Problems / Instant-on Start-up Time
• chapter 5.5 -- Interference / Figure 5.5-2 and Harmonic Interference
• chapter 6.3 -- Laser Radar Operation / Operation / Use
• chapter 7.1 -- Countermeasures / Radar Detectors, RDD's, and Laser Jammers
• chapter 7.2 -- The Courtroom / Preparation for Court and Visual Speed Judgment
• appendix A -- Frequency Spectrum / Traffic Radar Frequencies
• appendix C -- Doppler Equations / Table C-1 and Figure C-3
• appendix F -- Ladar Technical Details / Block Diagram

• Supplements (from Web version)
  chapter 3.3 -- Manufacturers
  chapter 5.1 -- NHTSA 1980 Tests : Test Data
  chapter 7.1 -- Countermeasures : Safety Warning Systems (SWS) text messages.
  Coordinated Universal Time (UTC)
  Links to other Sites

The Federal Commumications Commission (FCC) has allocated 13.45 GHz in the Ku band for traffic radar use in the United States, however Ku radars are not sold or used in the U.S. Some European countries are reported to use Ku band (13.45 GHz) traffic radars.

Aerial clocking, a stop watch, Distance/Time computer, VASCAR, road cables, inductive loops, Across the Road Laser, and down the road laser radar all use a form of distance traveled equals velocity multiplied by time (or velocity equals distance traveled divided by time). By knowing distance traveled and measuring the time it takes a target to travel the known distance, target velocity can be calculated. Any error in measured distance or time translates into a measured velocity error.

If distance used (d_o) to calculate speed is in error and low (short) by -d_err (operator input error), caluclated measured speed (v_m) is high by v_err. If distance used (d_o) to calculate speed is in error and high (long) by d_err, caluclated measured speed (v_m) is low by -v_err.

If measured time to calculate speed is in error and low (short) by -t_oerr (operator time error), caluclated measured speed (v_m) is high by v_err. If measured time to calculate speed is in error and high (long) by t_oerr, caluclated measured speed (v_m) is low by -v_err.

v_o = target velocity
t_o = time target travels distance d_o
d_o = distance target travels in t_o seconds
v_o = d_o / t_o
d_err = ± error in distance traveled
t_oerr = ± operator error in time target measured
v_err = ± measured target velocity ERROR

NOTE: when computing d_o,
if v_err is positive (+), d_err or t_oerr must be negative (-);
if v_err is negative (-), d_err or t_oerr must be positive (+).

Make sure unit dimensions work out; if distances in feet (or meters), velocities in feet per second (or meters per second).

             CALCULATE     GIVEN ------ & ----------------- & --------------

A.)        Speed Error     Target Speed   Distance Traveled   TIME ERROR
B.)         TIME Error     Target Speed   Distance Traveled   Speed Error
C.)  Distance Traveled     Target Speed   TIME Error          Speed Error

D.)        Speed Error     Target Speed   Distance Traveled   DISTANCE ERROR
E.)     DISTANCE ERROR     Target Speed   Distance Traveled   Speed Error
F.)  Distance Traveled     Target Speed   DISTANCE ERROR      Speed Error

The faster a target, the greater the time and distance required to calculate an accurate speed measurement. For most cases a small distance error produces a small speed error; however small time errors can produce significant speed errors in many situations. Timing calculations include time error due to both START and STOP timing (2 error sources).

Instant-On Start-up Time
Instant-on radars are not exactly instantaneous, some turn-on or warm-up time is required. In theory it is possible to transmit a steady stable signal in a few milliseconds (0.001 seconds) by leaving the transmitter on (no transmitter warm-up time) and dumping the signal into a dummy load until ready to transmit through the antenna. This technique requires a "make before break" switch (typical switching time 1 millisecond or so) to prevent microwave power from reflecting back to the transmitter causing damage. In practice (to save space, components, power, and cost) traffic radars turn the transmitter off (cut power from transmitter) until ready to transmit. This technique requires longer turn-on time to achieve a steady stable signal, typically less than a half second but can be as high as 2 seconds.

During (cold start) transition time from transmitter OFF to ON (transmitting a steady signal) the frequency is highly unstable -- any measurements have an error that depends on the change in frequency rate (called chirp), and the target range from radar. The greater the chirp and the greater the target range, the greater the error. Target range is a factor because the greater the range the longer the round trip (radar) signal time, and the longer the time for frequency to change. The error is positive (adds to measured target speed) for on-coming targets and negative (subtracts from measured speed) for receding targets. During transmitter start up on-coming targets, if measured at all, may measure high until the transmit frequency settles -- implying (falsely) to the radar operator the target vehicle started slowing down after radar illumated target.

Traffic radar measures the frequency difference between the transmit signal and target echo. If radar transmit frequency changes enough between the time the signal is transmitted and the time the echo received, a speed error occurs (echo frequency compared to a changed transmit signal). Change in frequency (chirp) rates for Ka band Gunn diode oscillators (transmitters) have been measured (Valentine Research, Inc. -- Radar Detector manufacturer) to vary between 0.0198 and 1.069 Hertz per nanosecond (Hz/ns). The below table list speed error based on target range using the slowest (0.0198 Hz/ns) and fastest (1.069 Hz/ns) chirp rates for a radar transmit frequency of 33.80 GHz. A medium value (0.544 Hz/ns) between the fastest and slowest rates is also shown. The longer the target range, the faster the chirp, and the lower the design (transmit) frequency -- the greater the speed error.

Radar speed measurements during first half second or so of transmitter (microwave Gunn diode oscillator) start-up are unreliable. Speed measurements (if any) during start up time should be ignored.

MPH Industries has several models (at least one operates at Ka band -- 33.8 GHz) with a POP mode -- transmits a 67 milliseconds (ms) burst (from a cold start) intended to avoid detection by radar detectors. Radar detectors cannot detect the short 67 ms burst, the trade-off is the radar gets an uncertain and unusable measurement. The operator is NOT allowed to lock target measured speed in POP mode, and the manufacturer recommends switching to normal mode for an accurate speed measurement. The POP mode is used as a selling feature, but has no real practical use (other than potential operator abuse). The POP mode is a useless feature because of the frequency instability resulting in speed measurement uncertainly, not to mention wasting time taking a bad measurement (operator must still use normal mode for several seconds to get an accurate measurement).

Operation

Use . . . last paragraph
• WAS
  Because ladar uses a narrow light beam, the ladar should not point through glass because the lightwaves may diffract and/or attenuate, reducing effective range. Flat clear glass will reduce ladar detection range; curved tinted glass reduces detection range greatly and may render the ladar unusable. Many windshields have coatings and/or tiny metal chips that reduce sunlight as well as severely degrade ladar detection range.

• IS
  Because ladar uses a narrow laser infrared (IR) beam, the ladar should not point through glass (windshields, side windows, etc.) because the beam will refract and some or much of the signal absorbed, reducing pointing accuracy and detection range. The degree of pointing error is a function of glass characteristics such as curvature, thickness, index of refraction, and the angle the beam strikes the glass. Signal attenuation is a function of glass absorption coefficient and index of refraction (tinting), thickness, and the angle the beam strikes the glass. Note that characteristics such as the index of refraction and absorption coefficient are wavelength dependent, may have slight to very different values depending on wavelength. Vislbile light has wavelengths between 400 - 700 nm (nanometers), ladar is in the infrared (IR) region at about 900 nm.

First paragraph, last sentence
Typically on average radar detectors require at least 150 milliseconds (150 ms = 0.15 seconds) to detect and identify a radar signal.

. . . add to SIGNALS DETECTED list

RADARS NOT USED IN USA
• X band radar (9.90 GHz)
• X band radar (9.41 GHz)
• Ku band radar (13.45 GHz)

  RDD -- RADAR DETECTOR DETECTOR (also see below)

• VG-2 Interceptor
• Stalcar, Stalcar A/C 3
  Spectre, Spectre II
• RD-1, RD-2, RD-2/Dual, RD-3

. . . revise COUNTERMEASURES list

• Immunity from radar detector detector (RDD)
  Immunity -- different LO's (see below), or detects RDD LO and shuts down.

. . . last paragraph
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

Spectre and Spectre II
The Spectre RDD was introduced by Stealth Micro Systems in early 2002, and is similar to the Stalcar RDD. The Spectre detects X, K, and Ka band radar dectectors using a swept LO from about 11 - 15 GHz. Used in the USA, Canada, and Europe.

Hill Country Research
527 Chaparral Dr.
Fredericksburg, TX 78624 (USA)

RD-1
The RD-1 radar detector detector comes in a small suitcase (or tool case) and is powered by 12 Vdc (from the car battery) that requires about 0.5 amperes. The large antenna allows for relatively long range detection on the order of about 2 miles (over 3 km) or more. Includes built-in self-test. Designed to be used during radar operation (the RD-1 should not interfere with microwave radars).

RD-2
The RD-2 radar detector detector is 6 x 6.5 x 3.25 inches (155 x 170 x 85 mm), powered by the car battery (12 Vdc) at about 0.5 amperes. Detection range is about 0.5 miles (0.8 km). Receiver bandwidth about 2 GHz.

RD-2/D
The RD-2/Dual radar detector detector is similar to the RD-2 with the addition of an off angle beam. The RD-2/Dual uses two beams, one pointed forward (0 degrees) and the other pointed at about a 45 degree angle (left side). The two beams indicate to the RDD operator the general direction of the radar detector (front or side).

RD-3
The RD-3 radar detector detector is a relatively small unit that measures 6 1/8 x 4 1/8 x 2 1/2 inches (156 x 105 x 66 mm). Uses power from the car battery (10 - 18 Vdc) with average current requirements of 0.3 A if signal present, and 0.12 A without signal. The unit indicates whether the incoming signal is in it's lower or upper receive band. Antenna diameter is 50 mm (about 2 inches).

Optional features include automatically activating / deactivating a video camera. When the RD-3 detects a signal (radar detector) a command is sent to the video system to start recording, when the signal stops a command is sent to the video system to stop recording.

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 transmits		constantly transmits		transmits when laser detected
Waveform:	IR pulses at fixed rate/width		IR pulses at fixed rate/width		IR pulses at rate/width of ladar
Set 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.

Preparation for Court

. . . 2nd paragraph

WARNING: In Wisconsin (Dec 2002) a judge was reported to have disregarded a defendant's evidence because the evidence was not submitted to the prosecutor at least 40 days before the trial. This results in an additional burden on the defendant not imposed on the prosecutor or police officer, the officer did (does) not automatically send the defendant evidence without a request. It would seem to be fair the prosecutor should be required to request (and not an automatic process) evidence if they want it (another example of don't confuse justice with the law). Check as soon as possible with the court or prosecutor's office if evidence submittal is required and time constraints.

Visual Speed Judgment

Some courts (Judges) will accept an officer's meager visual observation of target speed (even if all other evidence discarded). To test the officer's target speed assessment ability a defendant could introduce a video tape (if court has a VCR and TV) of a target at various speeds under similar circumstances the ticket was issued. Radar distance from target lane is the most important factor, the shorter the distance the harder to estimate speed visually. This could work against the defendant and in favor of the officer if the officer is proficient at estimating target speeds.

A defendant could also test the officers visual speed judgment by asking the officer to judge the speed of an object dropped from several feet. This is somewhat of a trick question because the velocity of a free falling object is constantly increasing. Of course someone adapt at visually judging speed might be expected to estimate object speed (instantaneous) upon striking the ground, or at least the average speed -- average speed is half (0.5) instantaneous speed.

t = time, d = distance object falls, v = instantaneous velocity at time t,
a = acceleration (due to gravity) = 32.2 ft/s² = 21.9 mph/s = 9.8 m/s² = 35.3 kmh/s.

.

Block Diagram . . . last paragraph

Lasers for traffic ladars typically generate average transmit power on the order of about 200 microwatts (200 µW) average. Peak transmit power (for a rectangular pulse) is a function of average power, interpulse period (time between leading edge of one pulse to another), and pulse width.

P_peak = Peak Power (watts)
P_avg = Average Power (watts)
t_pw = Transmit Pulse Width (seconds)
T = interpulse period (seconds between start of one pulse to the start of the next pulse)

Note: T = 1 / PRF
PRF in Hertz -- pulses per second (1/seconds)

Duty factor (duty cycle) represents the fraction of time the radar is transmitting.

• Chapter 3.3 -- Manufacturers: addresses and phone numbers.
• Chapter 5.1 -- NHTSA 1980 Tests: TEST DATA for specific models.
• Chapter 7.1 -- Countermeasures: Safety Warning Systems (SWS) text messages.
• Coordinated Universal Time (UTC)
• Links to other Sites

Traffic Radar Handbook
Print version Addendums / Revisions