Speed Measurement (RADAR/LASER)
How many cycles per second does the K band frequency go ?
72 cycles per second (CPS) per one mile per hour.
What is the wavelength at which LASER's operate ?
904 nanometers(nm) +/- 10nm.
How many cycles per second does the Ka band frequency go ?
99.6 - 105.4 cycles per second (CPS) per one mile per hour.
Absolute Speed Law
A given speed limit that is is in force at all times regardless of environmental conditions. Based on scientific studies and data.
If the speed reading is inconsistent with the operator's estimate of the target's speed...
A sweep error may be occurring.
85th percentile...
A traffic engineer's method of establishing speed limits.
The Florida Administrative Code requires that a RADAR operator keep...
A written log of all results of daily testing of RADAR devices.
How do you AVOID damaging the RADAR device ?
ABC (Antenna -> Box -> Current)
Parallax
Apparent movement of a fixed object when the viewer changes his or her position.
Pulse Repetition Rate
Certain number of pulses in each second of transmission usually 100-300.
What are three forms of mediums used in LASER's?
Crystals Gases Diodes (Synthetic Glass)
Same Direction - Direction sensing RADAR devices may automatically...
Determine a target faster or target slower condition.
When was RADAR developed and first used by police?
Developed in England before World War II and the first recorded use by police officers in 1947.
A LASER measures the distance to a target several times a second...
Each new measurement will be a new distance, if the target is moving.
Sweep Error
Erroneous high or low speed reading caused by changing the targeting point while transmitting laser pulses.
A LASER device determines the direction of the target's travel by...
Evaluating whether the distance of the target from the laser is increasing or decreasing.
The agency is responsible for having the LASER device tested...
Every six months by an electronic technician with qualification specified in the rule.
RADAR target fastest mode
Function of the RADAR unit that displays a second speed based on the next fastest signal.
What kind of diode does law enforcement LASER's use?
Gallium arsenide, which produce light in the infrared portion of the electromagnetic spectrum.
Who developed the laser concept and who built the first working LASER?
Gordon Gould developed the LASER concept in 1957. Theodore Maiman built the first working LASER using a Ruby Cylinder in 1960.
Direction sensing RADAR devices determine...
If the reflected signal's frequency is higher or lower than the transmitted signal's frequency.
What are some factors that may affect MOVING RADAR?
Interference of radar signals (reflective signs, electric power lines, transformers, police radios, CBs, microwave towers). Jamming. A harmonic.
LIDAR
Light Detection and Ranging
The RADAR operator is required to perform what daily ?
Light Test (Determines display works) Internal Test (Built in internal test) Tuning Fork Test. Speedometer Test (On all moving RADARS)
LASER operators are required to do what daily ?
Light test. (Display test) Internal Test (Built in test) Distance Test (Establish two permanent targets at known distances. Targets are set to a distance of at least 100 feet and separated by at least 100 feet. Measurements must be plus or minus one foot) Sight Alignment Test (Established by using a target at least 200 feet away)
Average of Least Squares
Mathematical process built into LASER devices by the manufacturer to eliminate inconsistent data. Establishes an expected return based on parameters set by the manufacturer. Any return outside these parameters will be rejected by the LASER device.
Batching Effect
May cause an incorrect display of the target and/or patrol vehicle's speed reading.
Shadowing
May cause patrol speed reading to be lower than the actual patrol speed, thus raises the target vehicle's speed reading.
What is a RADAR?
Measures distance and speed. Does this by transmitting radio waves to the target and measures HOW FAR AWAY the target is and how FAST it is moving. DOES NOT measure the distance to the target.
What are some uses of a LASER?
Medical, entertainment, industrial, inventory control.
Sweeping
Movement of the laser. Results in a gradual change in speed data, instead of a sudden change.
LASER targeting point
Needs to remain as close as possible to the same point on the vehicle.
Frequency
Number of individual waves transmitted in one second.
When doe relative motion occur?
Object reflecting the energy stands still and the transmission source moves. Transmission source stands still and the object reflecting the energy moves. Both transmission source and the object reflecting the energy move, as long as they move in different directions and/or different speeds.
Target Speed Discrimination Test
Occurs when the patrol car is accelerated or decelerated to match the target vehicle speed, and the target vehicle speed displays on the radar unit does not vary.
What are some safety considerations of speed enforcement?
Officer safety and motorist safety.
Panning Effect
Pointing of the antenna of the RADAR device toward the counting unit, causing an incorrect reading.
Same Direction Moving RADAR
RADAR which determines speeds of target vehicles traveling in the same direction as the RADAR.
The court holds the..
RADAR/LASER operator responsible for ensuring that testing has been completed.
What does RADAR mean ?
Radio Detection and Ranging
Scanning Effect
Rapid swinging of a RADAR unit antenna causing an incorrect reading.
Radio waves and light will travel forever unless...
Reflected, refracted, or absorbed.
According to the Basic Doppler Principle...
Relative motion is motion toward or away from the RADAR. Frequency of a RADAR signal changes due to relative motion. Amount of frequency change is dependent upon the speed of a vehicle.
How do LASER's operate?
Require a light source. Positioned between two reflective surfaces (mirrors), light reflects between the two gaining intensity. At a particular point the intensity is great enough it will emit a single beam of light through one of the reflective surfaces.
What are the benefits of speed enforcement?
Saves lives, prevents injuries, and reduces crashes.
What are two factors that may affect the correct operations of stationary RADAR?
Scanning Effect and Panning Effect.
Basic Speed Law
Section 316.183 F.S. No person shall operate a vehicle in excess of a speed that is safe and prudent for the conditions that exist at the time.
What are the considerations involved in establishing site locations for use in time/distance (average speed) measurement?
Selecting methods of measuring distance. (Steel measuring tape, survey equipment, lasers.) Minimizing site obstructions. Selecting reference points. (Choose points a vehicle actually crosses.)
What are some factors that affect a vehicles reflective-ity ?
Shape, size, and composition.
Radio waves transmitted by a RADAR device are characterized by...
Signal Speed (Speed of Light) Wavelength Frequency
Agencies are responsible for having RADAR devices tested every...
Six months by an electronic technician who holds one of the certifications specified in Rule 15B-2.009.
Signal Speed
Speed at which a radio wave travels, which is the speed of light.
What is the basic formula for computing speed from time and distance?
Speed equals Distance divided by Time (S = D/T)
What are three properties of LASER light?
Spreads very slowly. Occupies a small portion of electromagnetic spectrum. More intense than natural light.
The basic computation when operating OPPOSITE direction moving RADAR is?
Target Speed = Closing Speed - Patrol Speed TS = CS - PS
What are the basic computations for same direction moving RADAR?
Target Speed = Patrol Speed + Separation Speed TS = PS + SS OR Target Speed = Patrol Speed - Closing Speed TS = PS - CS
Stationary Angular (Cosine) Effect
The angle created between the target vehicle and RADAR. ALWAYS lowers the displayed target speed reading.
Doppler Shift
The difference between the transmitted and received signals (or frequency).
Wavelength
The distance from the beginning of a peak to the end of a valley of a radio wave.
To AVOID a sweep error..
The operator must release the trigger of the laser device when changing targeting points from one target vehicle to another target vehicle.
LASER devices determine a distance based on...
The time it takes a pulse to travel from the LASER to the target and back to the LASER.
If the reflected signal frequency is lower..
Then the target vehicle is moving away from the RADAR unit.
What is the name for the method of determining distance by a LASER device?
Time of Flight
What is the purpose of adjusting the RADAR sensitivity ?
To eliminate unwanted signals such as interference.
What are characteristics of the LASER used in speed enforcement?
Transmit light energy as a series of pulses. Pulse width and pulse repetition rate.
LASER and RADAR should be tested...
Twice daily, before and after enforcement activity.
What are the characteristics of moving RADAR?
Uses the Doppler principle to determine the speed of a target vehicle. Transmits one signal but monitors MANY reflected signals. Processes two reflected signals and determines two speed readings. (Low Frequency Doppler and High Frequency Doppler).
What are some MOVING angular (cosine) effects of MOVING RADAR ?
Vehicle approaching or receding could create a lower than actual speed reading. Can be the result of an angle created between the antenna and the roadway. May result form a highly reflective stationary object along the roadway. Lowers the patrol speed reading and raises the target speed reading.
What are the elements involved in completing a tracking history in stationary RADAR?
Visual estimation of target speed. Audio Doppler. Target Speed Display.
What are the elements involved in completing a MOVING RADAR tracking history ?
Visual estimation of target speed. Audio Doppler. Target Speed Display. Patrol Speed Verification. (Patrol car speed and the speedometer reading must be within +/- 3 miles per hour of each other)
What are the elements involved in completing a tracking history for SAME DIRECTION moving RADAR?
Visual estimation. Audio Doppler. Target Speed Display. Patrol Speed Verification. Target Speed Discrimination Test
Relative Motion
When a solid moving object traveling toward or away from the RADAR is detected.
Total stopping distance is...
a combination of reaction time and braking distance.
LASER's use each change in distance over time to...
determine the speed of the target.
LASER's used in the infrared portion of the electromagnetic spectrum have the benefit of...
greater range and no distraction to motorists.
The shorter the wave length the..
higher the frequency.
The longer the wavelength the
lower the frequency.
LASER light travels at the speed of light or ...
one foot every one-billionth of a second. (Nanosecond)
LASER (If the distance is decreasing)
the target is approaching +
LASER (If the distance is increasing)
the target is receding -
If the reflected signal frequency is higher...
then a target vehicle is approaching the RADAR unit.
Increased speed has a direct correlation on the rate of...
...Traffic crashes, injuries, and fatalities.
Stationary RADAR means...
...the RADAR must remain stationary.
RADAR does not have the capability to know..
..if the change in frequency results from a moving object or the radar moving.
What is the nationally recognized perception/reaction time during normal daytime conditions for a non-impaired driver?
1.6 seconds, based upon an average drag factor of 0.75.
What is the minimum distance required to measure speed accurately ?
300 feet.
Ka Band Frequency
33.4 - 36.0 GigaHertz
Major types of speed regulations include...
Basic Speed Law and Absolute Speed Law.
Pulse Width
Each pulse of a laser light has a duration period.
As the target vehicle recedes the reflected signal...
Frequency decreases.
LASER
Light Amplification of Stimulated Emission of Radiation.
What are three factors that affect a RADAR unit's decision to process ?
Reflective capability. Position. Speed.
Parallax will affect time-distance calculations by...
...changing the perceived location of a reference point, thereby changing the calculated time and raising or lowering the speed calculation.
What is the speed of light?
186,282 miles per second
K Band Frequency
24.15 GigaHertz
Florida Administrative Code requires requires regular testing for RADAR devices and LASER devices for?
Accuracy.
As the target vehicle approaches the reflected signal...
Frequency increases.
Wavelength x Frequency =
Speed of Light
Basic Doppler Principle
The scientific basis for RADAR.
How is light measured ?
Wavelength.
