Radar Flashcards
What does RADAR stand for?
Radio Detection and Ranging
What type of energy is transmitted by the Eagle 3 radar?
A continuous wave of electromagnetic energy
What is the transmitted frequency of the Eagle 3 radar?
34.9 GHz i.e. (34900 million Hertz) cycles per second
What is the wavelength transmitted from the Eagle 3 radar?
8.59 millimetres
What is the spread/width of the Eagle 3 radar?
The radar beam leaves the antenna and spreads out at an angle of 12 degrees (plus or minus 1 degree). This equates to 21 metres of spread for every 100 metres the beam travels forward. Effective length is nominally 600 metres.
What is the operating voltage of the Eagle 3 radar?
9.0 – 16.5 Volts DC
What does ‘LO’ mean when it appears on the radar instrument?
‘Lo’ will appear in the target speed display when the power supply voltage drops below the minimum operating voltage, ie 9.0 volts
What are the operational temperature ranges for the Eagle 3 radar?
- 30 degrees Celsius up to + 60 degrees Celsius.
What target speeds is the Eagle 3 capable of detecting?
16km/h – 330 km/h
What patrol speed is the Eagle 3 capable of detecting?
16km/h – 160 km/h
Combined patrol and target speeds will not exceed 330 km/h.
Why is reflection important to the operation of the Eagle 3 radar?
The Eagle 3 radar relies upon energy being reflected from an acquired target to operate.
What is Doppler tone?
The Doppler tone emitted by the Radar system is the Doppler shift frequency divided down for listening comfort.
• Divided by 6 in stationary mode, due to only one target moving
• Divided by 12 in moving mode, due to two vehicles moving
Why is a clear tone important during a valid speed check?
A clear tone indicates that the radar is monitoring only one target and is not being subject to any interference.
What is Doppler shift?
Doppler shift is the actual frequency change which takes place as a result of movement between antenna and target.
How can an operator check for segment faults in the display of the Eagle 3 radar?
Depressing and holding the ‘test’ button will illuminate all the displays. Upon releasing the ‘test’ button the Eagle III will complete an internal test sequence.
How does interference commonly affect the Eagle 3 radar?
Interference has 1 of 2 effects:
1. Display of a speed in the absence of a target
2. No displayed speed when a target is present
Interference DOES NOT add or subtract from any target speed reading.
What happens to the Eagle 3 radar when subjected to radio frequency interference (RFI)?
Radio Frequency detector is activated and causes the displays to blank and ‘rFI’ will be displayed.
Is the Eagle 3 radar capable of registering the speed of a motorcycle when a truck is in sight? Explain.
Yes, it is possible. However, the radar obeys inverse square law. Therefore, the truck having a larger reflective surface than a motorcycle would reflect more energy at a greater distance. The motorcycle would have to be much closer than the truck for the radar to register the speed of the motorcycle.
Explain inverse square law.
The amount of energy returned to the radar antenna from a target will be determined by two main factors:
1. The reflective area of the target (target size)
2. Distance between the radar antenna and target.
Why is it important to correlate the patrol speed with the checked speedometer during speed checks?
To ensure the radar is not subjected to any interference/s and to negate the possibility of an incorrect speed (patrol speed) being displayed as the result of an effect.
Prior to performing speed enforcement, operators must perform the following checks in relation to the checked speedometer at the commencement and conclusion of their shift. What are those checks?
- Visual check of the speedometer and wiring for any damage
- Ensure the two tamper-proof seals are intact and not damaged in any way.
- Turn on the digital speedometer and observe all segments on the 7-segment displays. Ensure all segments illuminate.
- At the commencement of your patrols conduct a correlation check of the digital speedometer and the patrol speed of the radar. Verify the accuracy of the digital speedometer is within +2 km of the patrols speed displayed on the radar.
- If there is a difference greater than + 2km/h or tamper-proof seals are violated all speed enforcement shall cease immediately and brought to the attention of the supervisor.
What is multipath interference?
It is two energies arriving at the receiver at different time intervals. It causes short blips on the audible tone and only occurs for very short periods.
• It is likely to occur on long straight roads where there is Armco railing and or similar barriers.
• Does not affect accuracy of speed readings.
• May cause the display to blank.
What are some examples of natural interference?
- Large trees
- Bushes
- Heavy rain
- Snow
- Windblown dust; and
- Fog
What are some examples of manmade interference?
- Large advertising signs, especially if they are moving
- Large broad bladed fans
- Fluorescent lights
- Power transformers
- X-ray machines
- Radio transmitters
- Mobile phones
The radar antenna should ideally be mounted on the outside of the police vehicle. How high off the ground should it be mounted?
• The antenna should be mounted externally on the vehicle
• Not more than 2 metres, and not less 1 metre from the ground
• Must face directly to the front and parallel with the roadway in moving mode
• Must face front or rear and parallel with the roadway in stationary mode
• Any repairs to the antenna are to be completed by the Radar Engineering Unit (REU). Operator must not undertake any repairs.
• Antenna must not be exposed to, or used, in inclement weather
Direction and Tilt are the two components that affect antenna aim, how does tilting the antenna affect the Eagle 3?
Tilting the antenna upwards increases the range, while tilting downwards decreases the range.
What is the effective range of the Eagle 3 radar?
There are several factors that determine the range of the radar. However, the effective operating range is nominated to be 600 metres.
In moving mode, how does the Eagle 3 determine the target’s speed?
• The radar will always establish patrol speed first.
• Target is identified and Closing Rate Speed (CRS) is calculated.
• Patrol speed is subtracted from the CRS to determine the target speed.
In moving mode, what must the Eagle 3 radar obtain?
It must obtain 2 doppler shift frequencies. Patrol speed (low Doppler) and combined speed (high Doppler).
How is patrol speed obtained?
Patrol speed is obtained from energy reflected off the roadway and surrounding objects.
How is Gross Error defined?
An error greater than 2 km/h
When conducting a correlation check of the digital speedometer and the patrol speed of the radar what speed range must be verified?
It must be verified that the accuracy of the digital speedometer is within plus or minus 2 km/h of the patrol speed displayed on the radar instrument.
What are the 5 main effects which a radar operator could encounter?
- Cosine effect
- Split Speed
- Differential effect
- Double Bounce
- Add-on speed
Consider ‘CSDDA’ acronym
What is the cosine effect?
Cosine is the angle in which the radar is to the target.
• As a target approaches the angle between the radar and the target increases.
• This slows the velocity of returning energy and gives a reading slower than the actual speed.
How can an operator avoid errors caused by cosine?
- Apply the 7:1 ratio to determine the range at which any speed check must cease or commence
- Correlate patrol speed with checked speedometer
What is the Differential effect?
• May occur in moving mode when a target is checked whilst a large reflective vehicle (truck/caravan) is immediately in front of the police vehicle.
• Whilst acquiring patrol speed a stronger reflection may be obtained from the vehicle resulting in the difference in speed between the two vehicles being displayed as the patrol speed erroneously.
What steps are operators able to avoid errors due to differential effect?
- Do not check the speed of a target whilst the police vehicle is close to the rear of a large moving object.
- Verify the patrol speed by correlation with the checked speedometer.
What is double bounce?
In moving mode, if the radar is released in the absence of a target, stationary objects normally used to assist in establishing a patrol speed retransmit the radar energy back towards the police vehicle and the radar to obtain a target speed from those objects.
• Wave fronts are not compressed by the objects
• Police vehicle becomes both host and target vehicle
• Avoid by keeping radar in hold until a legitimate target is observed.
How does split speed occur?
- Can occur when patrol vehicle travels in excess of 120 km/h.
- Radar is unable to obtain patrol speed from the roadway directly in front, instead obtains its speed from an angle.
- Due to cosine, the displayed patrol speed is slower than the actual speed.
- The radar obtains true ground speed but already has a patrol speed so it treats it as CRS.
- The difference between the Patrol Speed and CRS are displayed as a target speed.
How does add-on speed occur?
- Occurs when the patrol vehicle is travelling below the patrol speed threshold
- Occurs when establishing patrol speed, any oncoming vehicle within 50 meters is treated as a stationary object
- CRS is displayed as patrol speed
Eagle 3 is not susceptible to add on speed.
What causes a harmonic detection?
Occurs when reflections from objects or targets are the same as the patrol speed
What five behaviours associated with radar energy may be experienced by Eagle 3 operators?
- Reflection
- Refraction
- Re-transmitted
- Absorption
- Diffraction
Consider ‘RRRAD’ acronym
What is the accuracy of the Eagle 3 radar in both moving and stationary modes?
• Stationary mode: + or - 1 km/h
• Moving mode: + 1 or - 2 km/h
Why is it important to maintain a constant patrol speed?
- Allows easier and faster acquisition of patrol speed.
- Allows more time to calculate CRS.
What is the purpose for conducting the tuning fork test?
- To establish the transmitter / receiver (antenna) is functioning correctly
- To establish the accuracy of the Logic Control Unit (LCU)
Tolerance is + or - 1 km/h
Explain the procedure to conduct the mechanical tuning fork test procedure.
- Press the POWER button and observe the Eagle 3 cycle through the internal test sequence.
• All segments illuminated
• Pas displayed in target speed area and patrol speed area
• Crt, Pas and days until calibration due displayed
• Ant F2 r0 displayed indicating front antenna connected
Once the Eagle 3 has completed the internal test sequence, ‘FLo’ will be displayed in the target speed area and ‘TEST’ will be flashing in the lower right-hand corner of the display unit. This indicates that the radar is in tuning fork test mode. - Cause the ‘45’ tuning fork to vibrate and hold it about 15 centimetres in front of the antenna. Observe the numerals ‘45’ in the PATROL area and ‘PAS’ in the LOCKED SPEED area. Following a successful ‘45’ test, observe the numerals ‘FHi’ in TARGET SPEED area.
- Cause the ’80’ tuning fork to vibrate and hold it about 15 centimetres in front of the antenna. Observe the numerals ‘80’ in the LOCKED SPEED area and ‘PAS’ in the PATROL SPEED area.
- The Eagle III will then automatically conduct a moving mode test procedure. Successful completion of the moving mode test procedure is indicated by,
• The numerals ‘35’ displayed in the TARGET SPEED area
• The numerals ‘45’ displayed in the PATROL SPEED area
• The letters ‘PAS’ displayed in the LOCKED SPEED area
In moving mode, the 45 fork represents the patrol speed, and the 80 fork represents combined speed, ie 80km/h – 45km/h = 35km/h
What is the Eagle 3 testing procedure?
- Visually check antenna placement and alignment
- Press power switch on
- Observe all segments illuminate
- Internal test, certification days, front/rear antenna port connection
- Cancel the tuning fork test - Check and adjust audio settings
- Check and adjust range settings
- Carry out tuning fork test procedure
At the commencement of patrols ensure correlation between patrol speed and checked speedometer.
What are the requirements for a valid speed check?
- Visual observation and estimation of the target’s speed.
- Observe the numerals in the patrol and target displays.
- Clear and continuous tone (however pitch may vary)
- Correlation between patrol speed and checked speedometer.
- Duration of the check (steps 2, 3 and 4) must not be less than 3 seconds.
- Minimum of 200 metres between targets of similar size.
Consider ‘VOCCDM’ acronym
What are five operational guidelines for the Eagle 3 radar?
- Radar/Lidar is to be setup and tested as per instructions
- The minimum detection time is three seconds for a valid radar speed check
- At all times, the instrument is to be in HOLD mode until a target is visually observed
- Whilst patrolling, police vehicles must maintain a reasonable, constant patrol speed
- Ensure a clear audio tone is heard throughout the period of the check
- A general tolerance of 2 km/h should be borne in mind when completing TINS
A Section 137 certificate must be issued within what time period?
12 months preceding the date
What is the minimum detection time for a valid radar speed check?
Three seconds.
What mode must the instrument be in until a target is visually observed?
HOLD mode.
What must police vehicles maintain while patrolling?
A reasonable, constant patrol speed.
What should be ensured during the period of the speed check?
A clear audio tone.
What general tolerance should be considered when completing TINS?
2 km/h.
What is the time period for issuing a Section 137 certificate?
12 months preceding the date of the offence.
What should be done if a seal is broken on the radar during a check?
- Cease all speed enforcement duties. 2. Remove the radar from service. 3. Notify your supervisor. 4. Send the instrument to REU for repair with a report.
What are the four exemptions to having a speed measuring evasion article?
- The person was going to surrender the article. 2. The person did not know or could not have reasonably known the article fitted was being carried. 3. The device was not built as an article. 4. The vehicle was subject to a notice requiring the removal of the article within a specified time, and the notice had not expired.
When must the Eagle 3 radar be tested and by whom?
- At the start of the shift (operator). 2. Hourly intervals (operator). 3. At the end of the shift (operator). 4. Every 12 months (by the REU).
What must a vehicle be equipped with for radar operation?
- A shielded cable. 2. A checked speedometer.
Why should the radar only be used in areas where traffic is sparse?
To allow ease of target identification.
What is relative velocity?
The component of speed that travels directly towards the radar.
Can the speed of a vehicle be checked in moving mode when travelling in the same direction?
No, the Eagle 3 radar cannot determine the speed of a vehicle travelling in the same direction in moving mode.
What is the Doppler effect?
The apparent difference between the frequency at which sound or light waves leave a source and that at which they reach an observer.
What is reflection in radar operation?
The abrupt change in the direction of propagation of a wave which strikes the boundary between different mediums.
What is refraction?
When a ray of light meets the surface of separation between two transparent mediums, it is sharply bent or refracted.
What is diffraction?
When electromagnetic waves are restricted by an aperture or by the edge of an obstacle, some of the energy spreads into the region not directly in line with the source.
What is absorption in radar energy?
Radar energy can be absorbed by some compounds including fibre or rubber/plastic-based sponge, with water or material with high-water content being the most common.
What is the Doppler formula for stationary mode?
A speed of 1 km/h causes a Doppler shift frequency of 64.6Hz.
What is the Doppler formula for moving mode?
Combine the patrol and target speeds, then divide by 3.6 to obtain m/s.
What care should be taken with tuning forks?
Mechanical tuning forks must NEVER be struck against any material harder than the fork itself.
Who manufactures the Eagle 3 and what band does it use?
The Eagle 3 is manufactured in the USA by Kustom Signals Inc Kansas, and is a direct Doppler Ka-band Radar.
