Five-wheel meters are divided into contact type and non-contact type:
1. contact type: it consists of the fifth wheel instrument, sensor, secondary instrument and mounting frame. When testing, it is installed at the appropriate position at the rear or side of the car, and the small wheel touches the road surface, measuring the driving distance of the car and calculating the speed, and recording it with paper tape or displaying it with numbers.
2. Non-contact type: the computer is the core component, equipped with corresponding I/O interfaces and peripherals, and there is no way to contact. It uses photoelectric correlation filtering technology, illuminates the road surface through the photoelectric road surface detector (referred to as photoelectric head) installed on the vehicle, and converts the road surface image into a frequency signal and inputs it into the computer.
principle of operation
The instrument uses a special large-area silicon photoelectric device as a detector. When in use, install the instrument outside the car and aim the lens at the ground illuminated by the light. When driving, the random patterns on the ground are imaged by the optical system and scanned by the silicon photoelectric device. After photoelectric conversion and spatial filtering, the sensor only outputs a random narrow-band sine wave signal, and the frequency of the signal is proportional to the vehicle speed.
The signal output by the sensor is filtered and shaped by TRF bandpass tracking filter, and then converted into standard TTL pulse output. Each pulse five-wheel instrument strictly corresponds to the distance that the car traveled on the ground compared with the same period last year. After counting and microcomputer processing, the output signal can display the vehicle speed, distance, acceleration and elapsed time in real time, and can store and print data.
What are the principles and precautions?
1. When using a five-wheel watch, usually press &; Ldquo begins &; Press the rdquo key to enter the corresponding test system or enter the following menu, and press &; Ldquo end & Press rdquo to exit the test and return to the previous menu.
2. When the instrument displays products and information on the screen, you can press &; Ldquo sends &; The rdquo key turns off the screen backlight. Thereby shortening power consumption.
3. When using, the micro printer should be kept online (that is, the indicator light is on). Press the S/L key on the printer panel to turn off the printer indicator light and move the paper forward at the same time.
4. If you want to check the previous test results, you can press &; Ldquo, and then enter the corresponding test project and start the test. Print &; The rdquo key displays the final test result, and then press &; Ldquo & Ampuarr & amprdquo & Ampldquo & Ampdal & Amprdquo cursor keys can view the previous test results in a loop (Note: the test serial number shall prevail. If the last test is 0 1, it is considered that it has been stored twice, namely 00 and 0 1). News and publishing. Ldquo printing &; Key for printing test results. News and publishing. Ldquo sends &; Rdquo key sends test results through RS232 standard serial port. News and publishing. LdquoEnd & ampRdquo key, exit the viewing state and enter the testing state.
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