Technical Specification for Verification and Inspection of ...



| |Technical Specification for Verification and Inspection of Laser |S/N |CNMV 203 |

| |Speedometers | | |

| | |Rev |1 |

|Theis Technical Specifications is are developed pursuant to Paragraph 2, Articles 14 and 16 of the Weights and Measures Act. |

|The date of promulgation, document number, date of enforcement and content of amendment are listed as follows: |

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|Date of Promulgation |

|Document No. |

|(Ching-Piao-Szu-Tsu) |

|Date of |

|Enforcement |

|Content of Amendment |

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|１ |

|19.09.2006 |

|09540003940 |

|01.01. 2007 |

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|Reference standards: |

|DOT HS 809 239: Speed-Measuring Device Performance Specification-Lidar Module (2004) |

|IEC 60825-1: Safety of laser products - part 1. Equipment classification, requirements and user’s guide (2001/01) |

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|Date of Promulgation |Bureau of Standards, Metrology and Inspection, Ministry of Economic Affairs |Date of Enforcement |

|19.09.2006 | |01.01.2007 |

1. Scope: this specification applies to the Lidar Module (hereafter laser speedometer) that transmits coherent infra-red light pulses, measures the time of flight for the laser pulses reflected from moving vehicles, and then calculates and displays the speed of the target vehicle based on the pulse repetition rate.

2. Structure

1. The laser speedometer shall bear the model number, name or trademark of the manufacturer, and the serial number on the instrument.

2. Laser speedometers shall bear the specification of power supply.

3. The main part of a laser speedometer and its accessories, including power cord and signal connection line for testing, shall be fully equipped.

4. All the switches, press buttons, and twist buttons of the instrument and its accessories shall be functioning smoothly and reliably. There shall be no loosening or obstacle phenomena to interfere with the operation.

5. There shall be no obvious scratches or cracks that affect the reflection on the speed measurement.

6. If a laser speedometer is installed on a frame according to the operation manual, the instrument shall be stable and not shakable.

7. The speed indication of a laser speedometer shall be by digital indication.

8. The numbers indicating speed on a laser speedometer shall be clear and distinguished instantly.

9. The speed indication of a speedometer shall be expressed as kilometers per hour (km/h or kph).

10. The minimum digit of speed indication of a laser speedometer shall be equal to or less than 1 kilometer per hour.

11. The speed range of laser speedometers shall include at least the range from 16 km/h to 300 km/h.

12. A picture taken by a photo laser speedometer should be submitted with the instrument for verification.

13. Pictures taken by photo laser speedometers shall clearly distinguish the target vehicle and the plate number.

14. Pictures taken by photo laser speedometers shall at least provide the following information: serial number of the speedometer, time (including year, month, day, hour and minute), speed value and location, etc.

3. Verification, Inspection and Maximum permissible errors

1. Verification and inspection equipment: certificates of traceability and uncertainty shall be provided:

1) Aiming distance measuring equipment: resolution ≦ 1 cm

2) Universal counter or oscilloscopes

3) Laser power meter: wavelength shall cover 905 nm ± 50 nm and the power range shall meet requirements of IEC 60825 Class 1.

4) Speed measurement simulation system of the laser speedometer:

Delayed time range 0.2 (s ~ 5 (s

Input trigger < 100 ns

Pulse repetition rate no less than 390 Hz

2. Structure, performances and specifications of laser speedometers shall be inspected in accordance with the following items:

1) Structure and functions

2) Aiming distance

3) Laser power intensity

4) Speed detection accuracy

3. The verification of structure and function of laser speedometers are performed according to the items of Section 2. Verification of specification characteristics can be conducted only after the speedometers pass inspection.

4. Inspection of aiming distance of laser speedometers is as follows:

1) Placing the laser speedometer at 50 m from the aiming distance detection device as shown in Fig. 1

2) The reflection side of the target device is a disk with 25 cm diameter.

3) There shall be no obstacles behind the disk.

4) Carefully aim the center of the target device of the laser speedometer, press the measuring trigger and measure/record the indicated distance of the laser speedometer.

5. Verification of the laser power intensity of the laser speedometer:

1) Ensure that the wavelength setup of the laser power meter corresponds to the laser wavelength of the laser speedometer to be tested.

2) Shoot the laser light of the tested laser speedometer to a high-speed light detector and send the output of the detector to a high-speed universal counter or oscilloscope. The universal counter or oscilloscope will determine PRR (Pulse Repetition Rate). The device is shown in Fig. 2a.

3) Through the convex lens, the laser light of the tested laser speedometer penetrates the 7-mm aperture from the 100-mm location and shoots at the light detector of the laser power meter. Receiving continues for 10 seconds to read the maximum power of the laser light. The experiment device is shown in Fig. 2b (equipment allocation in reference to IEC 60825).

6. Detection the speed accuracy of laser speedometer requires changing the flying time of the laser pulse of the laser speedometer via speed simulation system, to simulate the distance changes of different speeds of vehicles. The verification is conducted as follows:

1) In the laboratory, place the testing module of laser speedometer to match the receiving/transmission module of speed simulation system, which includes receiver and transmitter as shown in Fig. 3.

2) Based on the velocity to be simulated (v), the simulation system will simulate the changes of a series of distances (d) and time (t) of moving vehicles. The formula is:

[pic]

[pic]

in which Cair represents the speed of light in the air (approx. 299705663 m/s) and tRT refers to the simulated back and forth time of laser light from the laser speedometer to the target vehicles.

3) Measure the Pulse repetition rate (PRR) and calculate the adjacent laser pulses time (t).

[pic]

4) Simulate the actual speed of moving vehicles with the data from (2) to (3).

5) With trigger of PC speed simulation program, to test the laser speedometer and speed simulation system.

6) Speed accuracy shall include no less than ten sets of test results at various distances and speed.

7. Maximum permissible errors for verification of laser speedometers:

1) Aiming distance: ±0.3 m。

2) Laser power intensity: pulse repetition rate≦390 Hz, pulse repetition rate variation ≦0.1 %。

3) Speed detection accuracy: +2 km/h, -3 km/h.

8. The maximum permissible errors for inspection are 1.5 times of the maximum permissible errors for verification.

9. The period of validity of verification is 1 year, commencing from the day of a verification compliance mark affixed to the speedometer and expiring on the first day of the following month of the following year.

4. Verification compliance marks

1. The place of verification compliance tag of laser speedometer shall be obvious and on the cover of the main part.

2. After the speedometer passes verification, a verification compliance certificate shall be issued.

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Laser speedometer aiming device

50 m

Fig. 1: Aiming Distance Device Inspection of Laser Speedometer

[pic]

Universal counter or oscilloscope

PRR Light Detector

Fig. 2a:. PRR Detection Device

Laser power meter

Diameter

Convex lens

Light Detector

Fig. 2b: Inspection of Laser Light Power

Fig. 3: Speed Accuracy Simulator Operation

Receiptving and transmission module

d

Speed simulation system of speedometer

PC

25cm

Uncovered space

NO GUARANTEE ON THE TRANSLATION

In case of discrepancies between the English translation and Chinese text, the Chinese text shall govern.

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