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RADAR STUDY GUIDE Questions with Detailed Verified
Answers
Doppler principle Ans: ✓ ✓ ✓ When energy (light, radio, or sound) is transmitted & is reflected by
or from a moving object its frequency will change in direct proportion to the speed. Moving closer =
increased frequency
What happens to the frequency in a stationary radar unit to an oncoming vehicle? Ans: ✓ ✓ ✓ The
wave will be higher in frequency and result in a higher pitch and a high measured speed
Target = Closing - Patrol Speed
If you extend the range on a radar device what may happen? Ans: ✓ ✓ ✓ Increased radar
sensitivity may hinder target acquisition and cause more spurious readings
Shadowing effects Ans: ✓ ✓ ✓ Moving mode - fixes target onto large object traveling in same
direction resulting in lower patrol vehicle speed and therefore increases target speed reading
calculation
(TS = CS - PS)
Generally requires 10+mph difference
Batching effects Ans: ✓ ✓ ✓ "Target Speed Bumping" - May cause high or low targe speeds due to
inability to maintain a current patrol vehicle speed. Usually caused by sudden changes in patrol
speed such as accelerating or braking "processor has a hard time telling what the heck you're
doing"
Spurious reading Ans: ✓ ✓ ✓ Outside or inside signals that may affect traffic radar (electronic
devices or movement, radio, heater fan). Maximum range setting will increase the chance of
spurious readings. "Interference cannot be additive to target speed."
What does a LIDAR do? How does a LIDAR work? Ans: ✓ ✓ ✓ Lidar uses the distance over time
principle to calculate speed. Measures the travel of light (Lazer) to the target and its reflection back
into the unit. Can be used in Stationary Mode Only
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Main court cases associated with RADAR. Ans: ✓ ✓ ✓ Daubert v. Merrell Dow Pharmaceuticals -
recognition of relevance and reliability of scientific evidence (Supreme Court)
(Frye was a D.C. Circ. Court case also regarding evidence and expert witnesses)
People v Ferency - Judicial notice of Doppler Principle
What must be determined at a court hearing for a speeding violation? (all factors) Ans: ✓ ✓ ✓
Preponderance of Evidence - 1. Citizen or Police officer witnessed speeding (CI) 2. Complaint must
be personally investigated by officer to establish "reasonable cause" 3. Prosecutor must approve in
writing the issuance of citation based on citizen's complaint 4. Establish Venue + 4 parts of traffic
code enforcement
Is an officer supposed to make a visual estimation of a speeding violator? Ans: ✓ ✓ ✓ YES; Doppler
Audio (Tone), Target Speed Display, Patrol speed verification in moving mode
(Does it match your speedometer?), Faster/slower mode verification
What is the signal look like in a standard radar utilizing the Doppler system? Ans: ✓ ✓ ✓
1.Stationary- transmission and reflected frequency is the same
2.Incoming- reflected frequency is higher than the transmission frequency 3.Retreating- reflected
frequency is lower than the transmission frequency
How does a radar work to calculate moving vehicles in the oncoming lane? Ans: ✓ ✓ ✓ Target
Speed = Closing speed - Patrol speed
Why is it an advantage to the violator when an officer is running stationary radar on the side of the
road? Ans: ✓ ✓ ✓ The cosine effect "will always lower the speed of the target vehicle." Ineffective
patrol car and antenna alignment
What is this called? (#13 above)
Example: A target vehicle is traveling at 50 mph at a 25 degree angle toward the unit. What will be
the display speed of the target vehicle if the angle is 0.90? Ans: ✓ ✓ ✓ Cosine (angular) Effect - 45
mph
Indicated speed = True Speed x cos(X)
Cos (25°) = ~0.9 ... 50mph x ~0.90 = 45 mph = Indicated speed
© Get it right 2025 Getaway - Stuvia US All rights reserved
RADAR STUDY GUIDE Questions with Detailed Verified
Answers
Doppler principle Ans: ✓ ✓ ✓ When energy (light, radio, or sound) is transmitted & is reflected by
or from a moving object its frequency will change in direct proportion to the speed. Moving closer =
increased frequency
What happens to the frequency in a stationary radar unit to an oncoming vehicle? Ans: ✓ ✓ ✓ The
wave will be higher in frequency and result in a higher pitch and a high measured speed
Target = Closing - Patrol Speed
If you extend the range on a radar device what may happen? Ans: ✓ ✓ ✓ Increased radar
sensitivity may hinder target acquisition and cause more spurious readings
Shadowing effects Ans: ✓ ✓ ✓ Moving mode - fixes target onto large object traveling in same
direction resulting in lower patrol vehicle speed and therefore increases target speed reading
calculation
(TS = CS - PS)
Generally requires 10+mph difference
Batching effects Ans: ✓ ✓ ✓ "Target Speed Bumping" - May cause high or low targe speeds due to
inability to maintain a current patrol vehicle speed. Usually caused by sudden changes in patrol
speed such as accelerating or braking "processor has a hard time telling what the heck you're
doing"
Spurious reading Ans: ✓ ✓ ✓ Outside or inside signals that may affect traffic radar (electronic
devices or movement, radio, heater fan). Maximum range setting will increase the chance of
spurious readings. "Interference cannot be additive to target speed."
What does a LIDAR do? How does a LIDAR work? Ans: ✓ ✓ ✓ Lidar uses the distance over time
principle to calculate speed. Measures the travel of light (Lazer) to the target and its reflection back
into the unit. Can be used in Stationary Mode Only
© Get it right 2025 Getaway - Stuvia US All rights reserved
, Click here for more: Scholars nexus
Main court cases associated with RADAR. Ans: ✓ ✓ ✓ Daubert v. Merrell Dow Pharmaceuticals -
recognition of relevance and reliability of scientific evidence (Supreme Court)
(Frye was a D.C. Circ. Court case also regarding evidence and expert witnesses)
People v Ferency - Judicial notice of Doppler Principle
What must be determined at a court hearing for a speeding violation? (all factors) Ans: ✓ ✓ ✓
Preponderance of Evidence - 1. Citizen or Police officer witnessed speeding (CI) 2. Complaint must
be personally investigated by officer to establish "reasonable cause" 3. Prosecutor must approve in
writing the issuance of citation based on citizen's complaint 4. Establish Venue + 4 parts of traffic
code enforcement
Is an officer supposed to make a visual estimation of a speeding violator? Ans: ✓ ✓ ✓ YES; Doppler
Audio (Tone), Target Speed Display, Patrol speed verification in moving mode
(Does it match your speedometer?), Faster/slower mode verification
What is the signal look like in a standard radar utilizing the Doppler system? Ans: ✓ ✓ ✓
1.Stationary- transmission and reflected frequency is the same
2.Incoming- reflected frequency is higher than the transmission frequency 3.Retreating- reflected
frequency is lower than the transmission frequency
How does a radar work to calculate moving vehicles in the oncoming lane? Ans: ✓ ✓ ✓ Target
Speed = Closing speed - Patrol speed
Why is it an advantage to the violator when an officer is running stationary radar on the side of the
road? Ans: ✓ ✓ ✓ The cosine effect "will always lower the speed of the target vehicle." Ineffective
patrol car and antenna alignment
What is this called? (#13 above)
Example: A target vehicle is traveling at 50 mph at a 25 degree angle toward the unit. What will be
the display speed of the target vehicle if the angle is 0.90? Ans: ✓ ✓ ✓ Cosine (angular) Effect - 45
mph
Indicated speed = True Speed x cos(X)
Cos (25°) = ~0.9 ... 50mph x ~0.90 = 45 mph = Indicated speed
© Get it right 2025 Getaway - Stuvia US All rights reserved
