Speed Measurement CJSTC #1158

K-band

24.15 gigahertz

What wavelength does police laser operate?

904 nanometers

Ka band is?

99.6 to 105.4 cycles per second (CPS) per one mile per hour

What is a radar target fastest mode?

A function of the radar unit that displays a second speed based on the next fastest signal

Absolute Speed Law

A given speed limit that is in force at all times regardless of environmental conditions. Based on scientific studies and data.

Identify how laser devices determine the target's direction

A laser device determining the direction of the targets travel by evaluating whether the distance of the target from the laser or decreasing - if the distance is decreasing, the target is approaching - if the distance is increasing, the target is receding

What is a same direction moving radar?

A radar which determines speeds of target vehicles traveling in the same direction as the radar

What is sweep error?

An erroneous high or low speed reading caused by changing the targeting point while transmitting laser pulses

What is parallax?

Apparent movement of a fixed object when the viewer changes their position

If the reflected signal frequency is higher, then the target vehicle is ______ the radar unit

Approaching

Identify how the Doppler Principle applies to stationary radar when the vehicles approach or recede

As the target vehicle approaches, the reflected signal frequency increases As the target vehicle recedes, the reflected signal frequency decreases

What is the internal test?

Built into the radar by the manufacturer and displays information indicating the radar is functioning properly

How does RADAR measure distance and speed?

By transmitting radio waves at a target snd measures how far away the target is and how fast it is moving

The batching effect may?

Cause an incorrect display of the target and/or patrol vehicle's speed reading

The shadowing effect may?

Cause patrol speed reading to be lower than the actual patrol speed. Thus raises the target vehicle's speed reading

In moving radar, a vehicle approaching towards or receding from a radar could?

Create a lower than actual speed reading due to the cosine

The number of cycles per second increases or decreases by?

Different amounts depending on the frequency of the radar used

Demonstrate the methods for testing a laser devices accuracy:

Display check, internal accuracy check, distance check, sight alignment check

Identify the basis of police traffic laser tracking history

Estimate each targets vehicle's speed visually, ensuring that an audio tone was present indicating that a target was acquired, obtaining a correlated readout on the traffic laser device

True or False: same direction RADAR is not based on Doppler Principle

False

Connecticut v. Tomanelli

First and most significant case in which the courts ruled that the testing methods used to check the radar's reliability and accuracy were valid. This case specifically pointed out the importance of using tuning forks to test a radar device

Appropriate identification of a driver from an authorized entity includes:

Florida drivers license or identification card, DAVID, authentic identification with a photograph issued by another state, passport, thumbprint on the back of the citation

Who developed the laser concept in 1947?

Gordon Gould

What is judicial notice?

Identified as court acceptance of scientific fact

What does the direction sensing radar device determine?

If the reflected signal's frequency is higher or lower than the transmitted signal's frequency

Sweep error may be occurring if?

If the speed reading is inconsistent with the operator's estimate of the target's speed

List factors affecting both stationary and moving radar operation

Interference of radar signals, jamming and harmonic

Identify the acronym for LASER

Light Amplification by Stimulated Emission of Radiation

What are the consistent properties of laser?

Limited divergence, narrow spectrum, high intensity

The moving cosine effect _____the patrol speed reading and ______the target speed reading

Lowers; raises

If the reflected signal frequency is lower, then a target vehicle is _____ from the radar unit

Moving away

Basic Speed Law

No person shall operate a vehicle in excess of a speed that is safe and prudent for the conditions that exist at the time

Identify safety considerations of speed enforcement

Officer safety, motorist/public safety

The displayed reading on the radar device in all tuning fork tests must be within _____ of the indicated tuning fork speed

One mile per hour

How is the tuning fork test conducted?

One or two certified tuning forks

What does site selection require?

Pre planning for safety entering and exiting the site

What is the acronym for RADAR?

Radio Detection and Ranging

Identify factors that affect the operation of police traffic laser devices

Reflection error, sweep error, color sensitivity, cosine effect, angle too great for return signal to be obtained

What are the three most common factors that affect a radar unit's decision process?

Reflective capability, postion, and speed

What is the basic Doppler Principle?

Relative motion, the frequency of a radar signal changes due to relative motion, and the amount of frequency change is dependent upon the speed of a vehicle

Honeycutt v. Commonwealth

Requires that a law enforcement officer be able to set up, test, and read a stationary radar device.

State v. Hanson

Requires that an officer must have sufficient training in and experience using moving radar

What is the basic formula for computing speed?

S=D/T

What are the benefits of speed enforcement?

Saves lives, prevents injuries and reduces crashes

What are the two factors that may affect the correct operation of stationary radar?

Scanning effect and panning effect

What are factors affecting a vehicle's reflectivity include?

Shape, size, compositon

Radio waves transmitted by a police traffic radar device are characterized by:

Signal speed (speed of light), wavelength and frequency

What is the amount of frequency change from a moving target dependent upon?

Speed of target

The basic computation when operating opposite direction moving radar is?

TS=CS-PS

The basic computations for same direction moving radar are:

TS=PS+SS and TS=PS-CS

What does the light test determine?

That all display indicators function properly

Rule 15B-2.009

The agency is responsible for having the police traffic radar device tested every 6 months by an electronic technician who holds one of the certifications specified in ______

What is the scientific basis for police traffic radar?

The basic Doppler Principle

What is the Doppler shift?

The difference between the transmitted and received signals (or frequency)

What is wavelength?

The distance from the beginning of a peak to the end of a valley of a radio wave

New Jersey v. Dantonio

The first judicial notice of the Doppler Principle involving police traffic radar. The result of this court ruling means that law enforcement officers do not have to explain in court how the Doppler Principle works

Identify the average of least squares

The mathematical process built into police traffic laser devices by the manufacturer to eliminate inconsistent data. Establishes an expected return based on parameters set by each manufacturer. Any return outside these parameters will be rejecting the laser device. Safeguards against erroneous readings

What is sweeping?

The movement of the laser results in a gradual change in speed data, instead of a sudden change in

What is stationary radar?

The radar does not have the capability to know if the change in frequency results from a moving object or the radar moving, thus means the radar must remain stationary

Identify the name for the method of determining distance by traffic laser

This method of determining distance is called "time of flight"

What is the purpose of adjusting the radar sensitivity?

To eliminate unwanted signals such as interference.

True or false: the stationary angular (cosine) effect always lowers the displayed target speed reading

True

What are the elements involved in completing a tracking history in stationary radar?

Visual estimatiok of target speed, audio Doppler, and target speed display

Identify the elements involved in completing a tracking history in moving radar

Visual estimstion of target speed, audio Doppler, target speed display, patrol speed verification (moving radar only)

What is relative motion?

When a solid moving object traveling toward or away from the radar is detected.

How can parallax affect time-distance calculations?

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

Light will travel forever unless

reflected, refracted, absorbed

Radio waves will travel forever unless

reflected, refracted, or absorbed

The fundamental of the three characteristics of radio waves can be expressed as the following formula?

wavelength x frequency = speed of light

Ka band

33.4-36.0 GigaHertz

K band is?

72 cycles per second (CPS) per one mile per hour

What is frequency?

The number of individual waves transmitted in one second

True or false: moving RADAR uses Doppler Principle to measure patrol vehicles speed

True

Patrol car speed and the speedometer reading must be within..

+/- 3 miles per hour of each other

What is the suggested minimum clocking distance?

300 feet

The speedometer test is performed on?

All moving radar by comparing the patrol speed readinf of the radar to the certifed speedometer

What is the stationary angular (cosine) effect?

The angle created between the target vehicle and the radar

How can you avoid sweep error?

The operator must release the trigger of the laser device when changing targeting points from one target vehicle to another target vehicle. The laser targeting point needs to remain as close as possible to the same point on the vehicle

What is a panning effect?

The pointing of the antenna of the radar device toward the counting unit, causing an incorrect reading

What is scanning effect?

The rapid swinging of a radar unit antenna causing an incorrect reading

Identify the relationship between wavelengths and frequencies

The shorter the wave length the higher the frequency, or the longer the wavelength, the lower the frequency. Wavelength x frequency = speed of light

What is signal speed?

The speed at which a radio wave travels, which is 186,282 miles per second, or the speed of light

Laser light travel at...

The speed of light or one foot every one-billionth of a second. One-billionth of a second is referred to as a nanosecond