Test and Calibration Range Finder
A rangefinder is a radio navigation device that measures the slant distance between an aircraft and a ground transponder. It consists of an airborne interrogator and a ground answering station. A method of determining the distance between the two by measuring the time it takes for radio waves to travel back and forth from an aircraft to a radio station. In aviation, the pulse wave near 1000MHz is used to inquire and answer, and its working distance is about 500km, which is used on the air route. In addition, in order to cooperate with the microwave landing system during approach and landing, a precision range finder has been developed, which uses the waveform of the pulse front with a faster rising rate to improve accuracy, and its operating distance is about 40km. The working frequency of the two rangefinders is the same, so they can work compatible
The rangefinder is a tool for measuring length or distance, and can be combined with angle measuring equipment or modules to measure parameters such as angles and areas. There are many forms of rangefinder, usually a long cylinder, composed of objective lens, eyepiece, display device (can be built-in), battery and other parts.
Laser range finders can also emit multiple laser pulses to determine whether an object is moving away from or approaching a light source through the Doppler effect.
Common rangefinders can be divided into short-range [2], medium-range and high-range rangefinders in terms of range;
From the modulation object adopted by the range finder, it can be divided into: photoelectric range finder and acoustic wave range finder.
According to the distance measuring method, the photoelectric range finder is divided into two types: the phase method range finder and the pulse range finder [4].
The pulse rangefinder uses a beam of light to the target object to measure the time for the target object to reflect the light back, thereby calculating the distance between the instrument and the target object. Because the laser has good directionality and a single wavelength, it is a photoelectric measurement The rangefinder generally uses laser as the modulation object, so the pulse type rangefinder is also commonly known as the laser rangefinder
