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thwp-ec radar > Eagle 3 Radar > Flashcards

Eagle 3 Radar Flashcards

1
Q

What does RADAR stand for?

A

Radio Detection and Ranging

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2
Q

What type of energy is transmitted by the Eagle 3 radar?

A

A continuous wave of electromagnetic energy

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3
Q

What is the transmitted frequency of the Eagle 3 radar?

A

34.9 GHz or 34, 900 million Hertz (speed of light)

plus or minus 0.1 GHz

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4
Q

What is the wavelength transmitted from the Eagle 3 radar?

A

8.59 millimetres

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5
Q

What is the spread of the Eagle 3 radar beam?

3dB Beamwidth

A

The radar beam spreads at an angle of 12 degrees (+ or - 1).

21 metres of spread for every 100 metres

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6
Q

What is the operating voltage of the Eagle 3 radar?

A

9.0 - 16.5 volts dc

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7
Q

What does ‘Lo’ mean when it appears on the radar display?

A

Low Voltage

‘Lo’ will be displayed in the target speed area and ‘Err’ in the patrol speed area.

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8
Q

What are the operating temperature ranges for the Eagle 3 radar?

A

-30 to +60 degrees Celsius

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9
Q

What is the Target Speed range of the Eagle 3 radar?

A

16 km/h - 330 km/h

Combined patrol and target speeds will not exceed 330 km/h.

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10
Q

What is the Patrol Speed range of the Eagle 3 radar?

A

16 km/h - 160 km/h

Combined patrol and target speeds will not exceed 330 km/h.

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11
Q

Why is reflection important for successful operation of the Eagle 3 radar?

A

The Eagle 3 radar requires energy being reflected from an acquired target to operate

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12
Q

What is Doppler Tone?

A

It is the tone emitted from the radar, which is the Doppler shift frequency divided down for listening comfort.

Divided by 6 in stationary mode (one moving vehicle)

Divided by 12 in moving mode (two moving vehicles)

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13
Q

Why is a clear tone important?

A

Indicates the radar is monitoring one target only and is not being subjected to interference.

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14
Q

What is Doppler Shift?

A

The actual frequency change which takes place as a result of movement between the antenna and target.

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15
Q

How can segment faults in the display be checked for on the Eagle 3 radar?

A

Depressing and holding the (✔) test button, which illuminates all segments.

Once the test button is released the internal test sequence will run

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16
Q

What two ways does interference commonly effect the Eagle 3 radar?

A
  1. Display a speed in the absence of a target
  2. No displayed speed when a target is present
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17
Q

What is RFI and what does the Eagle 3 radar display when subjected to it?

A

Radio Frequency Interference

Occurs when the radio frequency detector is activated, causing the displays to blank and ‘rFi’ to appear in the target speed area.

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18
Q

Is the Eagle 3 radar capable of registering the speed of a motorcycle when a truck is in sight? Explain.

A

Yes, it is possible.

The radar obeys inverse square law, meaning , the truck having a larger reflective surface than a motorcycle would reflect more energy at a greater distance.

The motorcycle would have to be significanlty closer than the truck for the radar to register the speed of the motorcycle.

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19
Q

Consider inverse square law.

What characteristics determine the amount of energy returned to the radar from a target?

A
  1. The reflective area of the target (target size).
  2. Distance between the radar antenna and the target.
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20
Q

What is the importance of correlating the patrol speed with the checked speedometer during speed checks?

A

To negate the possibility of an incorrect speed (patrol and/or target) being displayed as a result of an effect.

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21
Q

What is multipath interference?

A

It is the arrival of two energies at different time intervals at the radar receiver. It causes short ‘blips’ in the audible tone an only occurrs for very short periods.

May cause the display to blank

Does not affect the accuracy of any speed reading.

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22
Q

List examples of natural interference.

A
  • Large trees
  • Bushes
  • Signs
  • Heavy Rain
  • Fog
  • Snow
  • Windblown dust
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23
Q

List examples of man-made interference.

A
  • Large advertising signs, particularly if rotating or swinging
  • Large broad-bladed fans
  • Flourescent lights
  • Power transformers
  • X-ray machines
  • Medical diathermy machines
  • High voltage transmission lines with insulator leaks
  • Radio transmitters
  • Mobile phones
  • Automobile inverters
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24
Q

How high above the ground should the Eagle 3 radar be mounted?

A

The radar antenna must be mounted not less 1 metre and not more than 2 metres from the ground.

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25
Q

How does tilting the antenna affect the Eagle 3 radar?

A

Tilting upward increases range, while tilting downward decreases range.

26
Q

What is the effective range of the Eagle 3 radar?

A

The operating effective range is 600 metres.

Although the beam length is infinite

27
Q

In moving mode, what functions does the Eagle 3 radar perform to determine the target speed?

A
  1. Determine and display the patrol speed
  2. Determine the combined (closing rate) speed of radar and target
  3. Determine and display the target speed
28
Q

In moving mode, what frequencies must the Eagle 3 radar obtain?

A

It must obtain two doppler shift frequencies.

Patrol speed (low doppler) and combined speed (high doppler).

29
Q

How is patrol speed obtained by the Eagle 3 radar?

A

Patrol speed is obtained from energy reflected off the roadway and sometimes surrounding objects.

30
Q

How is Gross Error defined?

A

An error of 3 km/h or greater

31
Q

When conducting a correlation check between the digital speedometer and Eagle 3 radar patrol speed, what is the speed tolerance?

A

The accuracy of the digital speedometer must be within + or -2 km/h of the patrol speed displayed on the radar.

32
Q

What are the five main effects that impact the Eagel 3 radar?

A
  1. Cosine Effect
  2. Split Speed
  3. Differential Effect
  4. Double Bounce
  5. Add-On Speed
33
Q

What is the Cosine effect?

A

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 velocity of returning energy and gives a reading slower than the actual speed
34
Q

What steps are taken to avoid errors caused by cosine?

A
  1. Use of the 7:1 ration to determine the range at which a speed check must cease or commence.
  2. Correlate patrol speed with the checked speedometer.
35
Q

What is the Differential Effect?

A

May occur in moving mode when a target is checked whilst a large reflective vehicle (e.g. truck or caravan) is immediately in front of the police vehicle.

Whilst acquiring a patrol speed a stronger reflection may be obtained from the large vehicle in front resulting in the difference in speed between the two vehicles being displayed as the patrol speed.

36
Q

What steps are taken avoid errors caused by the Differential Effect?

A
  1. Do not check the speed of a target whilst the police vehicle is close to the rear of a large moving object
  2. Verify that the displayed patrol speed is in fact the true patrol speed by correlation with the checked speedometer
37
Q

What is Double Bounce?

A

In moving mode, if the radar beam is allowed to transmit when there is no target present, stationary objects normally used to assist in establishing a patrol speed (such as overhead bridges, billboards and road signs etc.) retransmit the radar beam back towards the police vehicle and the radar antenna, allowing for it to obtain a target speed from those objects.

Of Note:
- Electromagnetic waves are not compressed by the objects
- Police vehicle becomes both host and target vehicle
- Avoid by keeping radar in Hold until target is observed

38
Q

How does Split Speed occur?

A
  1. Can occur when the police vehicle is travelling in excess of 120 km/h
  2. Radar is unable to obtain patrol speed from the roadway in front of the vehicle, instead obtains speed at some angle to the side
  3. Due to the cosine effect the displayed speed is lower than the true patrol speed
  4. The radar then obtains the true ground speed but already has a patrol speed so treats it as the closing rate speed
  5. The difference between the patrol speed and closing rate speed is displayed as the target speed.

Adding the displayed patrol speed and target speed together will equal the true patrol speed, ± 2 km/h.

39
Q

How does Add-On Speed occur?

A
  1. Occurs when the patrol vehicle is travelling below the patrol speed threshold
  2. When establishing a patrol speed, any oncoming vehicle within 50 metres is treated as a stationary object as it will provide a better signal than the roadway
  3. Closing rate speed is displayed as patrol speed

Eagle 3 is not susceptible to Add-On speed due to GPS functionality.

40
Q

What causes harmonic detection?

A

Occurs when reflections from objects or targets are the same as the patrol speed.

Target area will blank or display ‘ - - -‘

41
Q

What are the five behaviours associated with radar energy?

A
  1. Reflection
  2. Refraction
  3. Re-transmission
  4. Absoption
  5. Diffraction
42
Q

What is the accuracy of the Eagle 3 in stationary mode and moving mode?

A

Stationary mode: + or - 1 km/h
Moving mode: + 1 km/h or - 2km/h

43
Q

Why is it important to maintain a constant patrol speed when utilising the Eagle 3 radar?

A
  1. Allows for eaiser and faster acquisiton of the patrol speed
  2. Allows for more time to calculate the closing rate (combined) speed
44
Q

What does the tuning fork test establish?

A
  1. That the transmitter/receiver (antenna) is functioning correctly
  2. The accuracy of the Logic Control Unit (LCU)
45
Q

What is the tuning fork test tolerance?

A

plus or minus (±) 1 km/h

46
Q

Within what time period must a Section 137 Certificate be issued?

A

12 months preceding the date of the offence.

47
Q

Consider Road Transport Act 2013, Section 119

What are the four exemptions to having a speed measuring evasion article?

A
  1. The device was not built as an article
  2. The person was going to surrender the article
  3. The vehicle was subject to a notice, requiring the removla of the article within a specified time, and the notice hand not expired
  4. The person did not know, or could not have reasonably known the article fitted was being carried
48
Q

What is the doppler shift frequency of 1 km/h?

A

64.6 Hz

49
Q

What must a vehicle be equipped with for radar use?

A
  • Shielded cable
  • Checked speedometer
50
Q

Why should radar only be used in areas with light traffic?

A

For ease of target identification

51
Q

What is relative velocity?

A

The componet of speed that travels directly towards the radar

52
Q

In moving mode, can the speed of a vehicle travelling in the same direction be checked?

A

No.

The operator does not need to be concerned about traffic travelling in the same direction as the radar vehicle.

53
Q

What is Doppler Effect?

A

The apparent difference between the frequency at which sound or light waves leave a source and that at which they reach the observer.

54
Q

Consider the behaviour of radar energy

What is Reflection?

A

The abrupt change in the direction of propagation of a wave which strikes a boundary between different mediums.

Radar relies on energy being reflected from a target to operate. Ideally, the radar beam should strike the target perpendicular to its surface.

55
Q

Consider the behaviour of radar energy

What is Refraction?

A

When a ray of light meets the surface of separation between two transparent mediums and thus is sharply bent or refracted.

Into a more dense medium: bends towards the normal

Into a less dense medium: bends away from the normal

56
Q

Consider the behaviour of radar energy

What is Diffraction?

A

When electromagnetic waves are restricted by the edge of an obstacle (or aperture), some of the energy spreads into the region not directly in line with the source. Simply put, the bending of electromagnetic waves.

As the aperture size decreases the effects of diffraction are increased.

57
Q

Consider the behaviour of radar energy

What is Absorption?

A

When radar energy is absorbed by energy-absorbing compounds.

This can occasionally result in substantial loss of range.

Most common being water and any material with a high water content, e.g. grass, leaves and shrubs as radar transmits at 34.9 GHz.

Some other compounds are fibre, rubber and plastic based sponge (but are impractical as a radar avoidance measure).

58
Q

List 5 Operational Guidelines

A

Refer to Operator Manual

59
Q

When is radar or lidar not to be used?

A
  1. Within 50 metres of a change speed zone being enforced, unless:
    - Speed is excessive (more than 20 km/h)
    - Subject of complaint
    - Where there is a high accident history
    - Does not apply to school zones
  2. At any location or deploy a vehicle that would engender legitimate criticism or give rise to the complaint that they are a means of raising Government revenue.
60
Q

What are the requirements for a valid Radar speed check?

A
  1. Visual observation and estimation of the target’s speed.
  2. Observe the numerals in the patrol and target displays.
  3. Clear and continuous tone (however pitch may vary).
  4. Correlation between patrol speed and checked speedometer.
  5. Duration of the check (steps two, three and four) must not be less than three seconds.
  6. Minimum of 200 metres between targets of similar size.

thwp-ec radar (2 decks)

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