Download NC Radar State Exam 2025: Questions and Answers on Speed Enforcement and Radar Technology and more Exams Law in PDF only on Docsity!
NC RADAR STATE EXAM 2025 QUESTIONS AND
ANSWERS GRADED A+
Does North Carolina have a prima facie speed law?
There is no prima facie speed law in NC
What are the Elements of a Speed Offense?
Driver ID, Location, Speed & Conditions
Elements of a Speed Offense: Driver Identification
Upon observing a violation, the officer should make an immediate visual identification of the driver. After this, during the "citing" portion, the officer should note more detailed identifiers (scars, birth marks, hair color, etc.)
Elements of a Speed Offense: Location
Establishing where the defendant's vehicle was being operated at the time of the infraction.
Elements of a Speed Offense: Speed
Measurements of speed obtained by RADAR are corroborative only in establishing the element. It is incumbent upon the officer to produce more detailed information to show the courts that the defendant's speed was unreasonable or imprudent
Elements of a Speed Offense: Conditions
The officer must gather information to show that the speed should be considered unreasonable in light of existing conditions (weather, roadway characteristics, vehicle conditions)
The 1973 Oil Embargo led to what?
the 1974 passage of the national 55mph maximum speed
55 mph was chosen because it is the Median Energy Efficiency Speed
As a result of the 55mph national speed limit, traffic fatalities decreased by
16.8%
The 55mph speed limit law remained in effect until
April 2, 1987
the National Maximum Speed Limit. In doing so, ended a period of more than 20 years of Federal involvement in the states establishment of speed limits and ended the requirements for states submission of speed compliance data to the Federal Highway Administration
In NC, speeding remains a major factor in highway deaths and serious injuries. In 2009, the National Highway Safety Administration Traffic Safety Facts (TSF) illustrated what?
That speed attributed to 39% of all highway deaths. We find in the TSF for 2014 in NC that 38.7% of all highway deaths were attributed to speed. On a national level, the TSF also indicates that for the full year of 2013, 42% of speeding drivers in fatal crashes also had a blood alcohol concentration of .08 grams per deciliter or higher
It was known that radio waves could be reflected from solid objects as long ago as 1886, but what brought about serious research and development of RADAR?
The threat of war in Europe in the late 1930s
Range information can be expressed in what?
Yards or feet
The antenna of the RADAR unit does what?
Shapes, forms, transmits, and receives microwave energy
How many hours are required by the state for radar training's Operator Course
30 Hours over 4 Weeks
What is the basic goal of all police work?
To protect the lives and property of the public.
65% of all fatal crashes occur in a speed zone of?
55 MPH or more
NHTSA
National Highway Traffic Safety Administration, the federal agency dedicated to achieving the highest standards of excellence in motor vehicle and highway safety
Radar is only a ___.
Tool
RADAR
RAdio Detection And Ranging, a system that uses reflected radio waves to determine the velocity and location of objects
Brazier v. City of Philadelphia (1906)
Affirmed a conviction under a city ordinance for speeding over 7 mph - "It is only necessary to resort to the most cursory observation to find the evidence that many drivers of automobiles in their desire to put their novel and rapid machines to a test of their capacity, drive such vehicles through the streets with a reckless disregard of the rights of others."
Increased speeds affect the 3 Elements of Driving, which are:
- The Operator - increased speeds serve to tax the basic capabilities of the driver, such as his reaction time (the time required to respond to a situation) as well as amplifying any existing physical deficiencies, such as vision
- The Vehicle - increased speeds tax the automobile equipment, the brakes, steering, etc.
- The Road Surface - increased speeds amplify the potential hazards of any deficiencies in the road surface (potholes, construction, etc.) or situational conditions resulting from weather, ice, snow, or rain
At a speed of 20 MPH, what is the stopping distance?
Reaction Time Distance = 22ft
Braking distance = 20 ft.
Stopping distance = 22ft + 20ft = 42 ft
At a speed of 40 MPH, what is the stopping distance?
Reaction Time Distance = 44 ft
Braking distance = 81 ft
Stopping distance = 44ft + 81 ft = 125 ft
Note the braking distance is 4 times that of 20 mph
At a speed of 80 MPH, what is the stopping distance?
Reaction Time distance = 88ft
Braking distance = 410 ft
Stopping distance = 88 ft + 410 ft = 498 ft
Note the braking distance is more than 16 times that of 20 mph
According to Joseph Nathan's "Famous First" the very first traffic law in America was?
Passed on June 12, 1652 by New Amsterdam (now New York). It prohibited the riding of horses at a gallop, or driving a horse-drawn vehicle at a galloping speed, within the city limits.
The energy transmitted by an antenna will do what?
Travel indefinitely unless absorbed, reflected, or refracted.
Radio energy always travels at what speed?
186,000 miles per second
30,000,000,000 centimeters per second
The speed of light
The frequency (cycles per second) of a radio signal changes when the signal is reflected from a target that is moving at a different speed than the RADAR device. This change or shift is known as?
The "Doppler Shift." The greater the relative velocity, the greater the frequency shift. By measuring the degree of frequency shift, the RADAR is able to display the target-vehicle speed in miles per hour
While the signal speed remains constant (speed of light), what other two characteristics of radio waves are variable?
The wave length, and the frequency
Wave Length
The physical distance, or length, from the beginning of the peak to the end of the valley.
Frequency
The number of waves transmitted in one second of time
Frequency is measured in what?
Cycles per second. One cycle is the same thing as one wave. Scientists and engineers often use the term Hertz (Hz) instead of cycles per second. All of these terms have the same meaning: one Hertz equals one cycle per second, which equals one wave per second
X-Band RADAR signal
has a wave length of approx. 3 centimeters (1.1 inches) and a frequency of 10,525,000,000 waves per second, or 10.525 Gigahertz.
K-Band RADAR signal
has a wave length of about 1.25 centimeters (.49 inch) and a frequency of 24,150,000,000 waves per second, or 24.150 Gigahertz.
Relative motion will only occur when the solid object and the RADAR are not moving in the same direction, at the same speed. Relative motion will occur if:
- The RADAR stands still and the object moves
- The object stands still and the RADAR moves
- If they are both moving, as long as they move at different speeds, or in different directions so that the distance between them changes
The smaller the angle
the closer to true speed
the greater the angle
the greater the angular effect (slower measurement)
You want the antenna as close to straight ahead as possible. Do not use more than what degree of an angle when running RADAR?
Do not use more than a 20 degree angle
The angular effect is sometimes called
the cosine effect
The angular effect causes the stationary RADAR speed measurement to be lower than the object's true speed. This effect always works in who's advantage?
It works to the motorist (suspect)'s advantage when the RADAR is operated in stationary mode
When may a RADAR unit not "see" an object?
Depending on the size, shape, speed, composition, and exact location of the object, its reflected signal may not be "seen" by the RADAR unit
A RADAR beam will go on forever until:
Either absorbed, reflected, or refracted.
A beam whose angle is 11 degrees will be more 38 feet wide at what point down the road?
200 feet down the road
What target composition will "refract" a RADAR signal?
Glass, plastics
What target composition will "absorb" a RADAR signal?
Leaves, sand, grass, earth
If we set the sensitivity to "low"
the RADAR will only respond to very strong signals and we usually will see only nearby targets
If we set the sensitivity to "high"
Even relatively weak reflected signals can be "seen", and we will be able to measure the speed of more distant vehicles
What range setting should be used where vehicles tend to travel clustered close together?
A "short" range setting should be used to provide reasonable target selectivity
If there is any doubt in your mind as to which target vehicle is being tracked
TAKE NO ENFORCEMENT ACTION
What features on RADAR instruments are not authorized for use in NC?
"Automatic locking" features - which cause the RADAR to "freeze" as soon as the speed measurement reaches some specified level
When facing a possible selectivity problem, what should the operator do?
The operator should not lock a target vehicle speed, and observe what happens when the vehicles pass out of the beam
All RADAR instruments approved for use in NC are required to have what?
An audio tracking feature
The rules of evidence in North Carolina require that facts necessary to prove the essential elements of a case be established by testimony or evidence. Therefore, an officer must have the ability to form an opinion as to speed in order to substantiate a speeding charge. Who else may testify as to the rate of speed?
"Any person of ordinary intelligence, who has had an opportunity for observation, is competent to testify as to the rate of speed"
Man-Made Objects "Interference"
Moving objects, such as rotating signs, will reflect the RADAR beam and cause Doppler shifts. rotating blades of fans (such as those found on buildings, roofs, and A/C units" can also act as "false targets".
What caused the infamous "85 mph tree" in Dade County, 1979?
A CB radio transmitter located in the same vehicle the RADAR was keyed on at that instant and the reporter whistled into the microphone.
When the CB and the RADAR are extremely close together, interference can result.
What caused the "28 mph house" in Dade County, 1979?
The RADAR unit actually measured the speed of the defroster fan's blades
The "Scanning" Effect
This effect occurs when the RADAR unit itself is moved - swinging the instrument creates relative motion between the RADAR unit and the stationary object
The "Panning" Effect
This effect only happens in two-piece RADAR units - if the antenna is pointed at its own counting unit, an erroneous speed measurement might appear on the display
The "Harmonic" Effect (signal incoherence)
It is a doubling, tripling, fractioning, or incoherent reflection(s) of a signal/frequency
"Jamming"
Purposeful attempts to create false or distorted RADAR signals.
The most common device is a RADAR frequency transmitter
The FCC
(Federal Communications Commission) regulates the television and radio industry, grants licenses to television and radio stations, and blocks monopolies.
These "jammers" have no effect on speed-measuring RADAR
Aluminum paint stripes or metal foil strips - if anything it increases the vehicle's ability to reflect the beam
hanging chains to the underside of the vehicle
