JJG 527-2015Fixed Radar Vehicle Speed Measurement Devices (English PDF)

5.4 Field test speed measurement error

When < 100 km/h, it is (-6~0) km/h;

When >=100 km/h, it is (-6~0)%.

6.1 Appearance

6.1.1 Fixed radar vehicle speed measurement device shall have a nameplate to indicate product name, specification, model, number, nominal value of radar emission frequency, manufacturer and date. It shall indicate manufacturing license mark and number of measuring instrument.

6.1.2 Fixed radar vehicle speed measurement device shall not have mechanical damage that affects normal use on its look. Each fastener shall not be loose;

structure shall be complete.

6.2 Requirements

6.2.1 Setting or adjusting keys of fixed radar vehicle speed measurement

device shall be used as normal. Operating keys shall be light and flexible, with normal operation.

6.2.2 Cable and connector of fixed radar vehicle speed measurement device

shall be complete, with reliable connection.

6.2.3 Fixed radar vehicle speed measurement device shall have independent speed display unit. After normal working, the display of display screen shall be complete, clear and eye-catching.

7.1 Verification conditions

7.1.1 Environmental conditions for verification

7.1.1.1 Laboratory verification environment:

1) Temperature: (15~25)°C.

2) Relative humidity: < 85%.

methods in 7.3.1, 7.3.2, 7.3.3, verify general technical requirements, microwave emission frequency error, speed measuring range, simulating speed measurement error and field test speed measurement error first. Record valid data. Then according to method in 7.3.4, verify field test speed measurement error. In follow-up verification, microwave emission frequency error, speed measuring range, simulating speed measurement error can be exempted from verification.

7.3.1 Inspection of general technical requirements

After fixed radar vehicle speed measurement device is turned on, it shall be able to work as normal. Use hand-feeling, visual inspection methods to inspect.

Results shall meet requirements of 6.1, 6.2.

7.3.2 Verification of microwave emission frequency error

Schematic diagram of microwave emission frequency verification error of fixed radar vehicle speed measurement device is shown as Figure 1. Make receiving antenna and microwave transmitting antenna of fixed radar vehicle speed measurement device are on a same axis. Connect output terminal of receiving antenna to microwave digital frequency meter.

Figure 1 -- System block diagram for verification of microwave emission frequency error

Turn on power of microwave digital frequency meter, fixed radar vehicle speed measurement device. Pre-heat according to instructions on use of instrument.

Make fixed radar vehicle speed measurement device continuously emit microwaves. Read measurement values on microwave digital frequency meter.

Measure microwave emission frequency 3 times. Microwave emission frequency error is calculated according to formula (1):

Where,

- microwave emission frequency error of fixed radar vehicle speed

Fixed radar vehicle speed measurement device

Receiving antenna Microwave digital frequency meter

Install according to use requirements for standard speed-measuring device for field test (or standard speed-measuring device). Adjust to make it under normal working state. Verification personnel shall, on installation road of fixed radar vehicle speed measurement device, according to actual situation of road, select one of the following methods to perform verification of field test speed measurement error:

(1) Under real traffic flow status, use normal-driving vehicle as measured object. Standard speed-measuring device for field test and fixed radar vehicle speed measurement device shall measure the same tested object in testing area simultaneously. Record 30 sets of valid measured values.

Each speed-measuring error shall meet requirements of 5.4. See Annex

A for specific operation.

2) Testing vehicle that is equipped with standard speed-measuring device drives at a constant tested speed. Standard speed-measuring device measures and displays speed when testing vehicle drives through testing area. At the same time, fixed radar vehicle speed measurement device measures speed of testing vehicle. Speed point of first verification is about

50%, 100% of limit speed. Perform at least two verifications for each tested speed. Each field test speed measurement error shall meet requirements of 5.4. Speed point of follow-up verification is about 100% of limit speed. Perform at least 3 verifications. Each field test speed measurement error shall meet requirements of 5.4.

In case of dispute, use the second method as arbitration verification method.

Filed speed-measuring error is calculated according to formula (2):

Where,

- field test speed measurement error, km/h;

v - measured speed of fixed radar vehicle speed measurement device, km/h;

v0 - measured speed of standard speed-measuring device for field test or standard speed-measuring device, km/h.

Relative field test speed measurement error is calculated according to formula (3):

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