Multicycle modulation method applied to laser ranging device using chirp amplitude modulation based on heterodyne detection

A technology of multi-period modulation and laser ranging, which is applied to measuring devices, using re-radiation, re-radiation of electromagnetic waves, etc., can solve the problems of reducing the resolution of the measurement, affecting the measurement accuracy, and detecting poor signal-to-noise ratio. Minimizes interference with low-frequency noise, improves performance, and increases the effect of frequency

Active Publication Date: 2010-07-28
SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI
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Problems solved by technology

Then the frequency difference f x The measurement is easily interfered by the low-frequency noise of the system and the laser phase noise, which affects the measurement accuracy
If the laser pulse length T is short, the energy of the laser pulse is low, the detection signal-to-noise ratio is poor, and the frequency spectrum resolution is low during frequency calculation, which reduces the measurement resolution
Therefore, there is a certain contradiction in the selection of the laser pulse length.

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  • Multicycle modulation method applied to laser ranging device using chirp amplitude modulation based on heterodyne detection
  • Multicycle modulation method applied to laser ranging device using chirp amplitude modulation based on heterodyne detection
  • Multicycle modulation method applied to laser ranging device using chirp amplitude modulation based on heterodyne detection

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[0041] The following is based onfigure 1 A preferred embodiment of the present invention is given to further present the technical details of the present invention so as to better illustrate the features and functional characteristics of the present invention, but it is not used to limit the scope of the present invention.

[0042] The multi-cycle chirp signal source is composed of a direct digital synthesizer DDS (Direct Digital Synthesizer), the output chirp signal starts at 80MHz, the signal frequency ranges from 80MHz to 280MHz, and the length of a single chirp is 1ms. After the chirp signal frequency increases linearly from 80MHz to 280MHz, it immediately jumps back to 80MHz and starts a chirp cycle again. The multi-period chirp signal source includes an external trigger signal, which continuously sends out 4-period chirp signals after triggering, and the total length of the multi-period chirp signal is 4ms.

[0043] The acousto-optic frequency shifter is IPF-600-60-1550-...

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Abstract

The invention discloses a multicycle modulation method applied to a laser ranging device using chirp amplitude modulation based on heterodyne detection. Continuous 4 to 10 cycles of chirp signals are used to modulate single laser pulse amplitude to realize laser ranging; and the method improves the signal frequency of the chirp difference frequency. In the invention, the laser ranging precision is improved due to the calculation method based on weighted average of spectrum power when in extraction of frequency information.

Description

Technical field: [0001] The invention relates to photoelectric instrument technology, in particular to a multi-period modulation method applied to a chirp modulation laser distance measuring device. Background technique: [0002] At present, laser ranging is mostly based on two systems. One is to use the time-of-flight of laser pulses to achieve ranging. This method uses the high power characteristics of pulsed lasers to achieve long-distance measurement, but the ranging accuracy is limited by the laser pulse width. limited, and the working life of the pump source of the pulsed laser is often limited; the other uses a modulated continuous wave laser or a long laser pulse to achieve distance measurement by measuring the relative change of the modulated signal in the echo. This method can achieve high Accurate distance measurement, but due to the limited continuous laser power, long-distance measurement cannot be achieved. Modulated ranging devices based on direct detection c...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S17/10
Inventor 孟昭华洪光烈舒嵘
Owner SHANGHAI INST OF TECHNICAL PHYSICS - CHINESE ACAD OF SCI
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