Signal processing method for eliminating velocity ambiguity in velocity measurement using pulse coherence method

Abstract

The invention discloses a signal processing method for eliminating velocity ambiguity in velocity measurement using a pulse coherence method. The signal processing method comprises steps of: dividinga velocity space into a plurality of velocity sections and using a section median as a base velocity; obtaining the roughly measured velocity of a target by using a time difference of the two echoes of the target so as to search for the velocity section and determine the base velocity; obtaining a precise time delay by using a phase difference of the two echoes so as to calculate a velocity offset; adding the base velocity to the velocity offset to obtain an original pre-measured velocity; adding an artificial time delay to one of the echo signals in order that the measured velocity generatesan artificial velocity offset, re-determining the base velocity and the velocity offset, adding the base velocity and the velocity offset to obtain a delayed pre-measured velocity; subtracting the corresponding artificial velocity offset from the delayed pre-measured velocity to obtain a corrected delayed pre-measured velocity; calculating the weighted average of the original pre-measured velocityand the corrected delayed pre-measured velocity to obtain a final velocity measured value.

Description

technical field [0001] The invention belongs to the technical field of signal processing methods, and in particular relates to a signal processing method for eliminating velocity ambiguity in pulse coherent velocity measurement. Background technique [0002] The Pulse-to-pulse Coherent Doppler (Pulse-to-pulse Coherent Doppler) method is used to measure the velocity of the target object or medium, which is widely used in the fields of sonar and radar. For example, weather radar uses this method to measure atmospheric wind speed, airborne radar to measure ground speed, and ground radar to measure speed to air targets; Acoustical Doppler Current Profiler (ADCP) uses this method to realize fluid velocity profile Measurement, medical ultrasound uses this method to achieve blood flow measurement and so on. [0003] The basic principle of the pulse coherent Doppler method for speed measurement is that two identical radio frequency (radar or sonar) pulses s(t) are successively tran...

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Problems solved by technology

From the above description, it can be seen that the extended measurement range of the double pulse repetition time method is limited

[0038] (2) Multi-pulse repetition time method: including triple pulse repetition time method (triple PRT), and multi-pulse repetition time method (M-PRT), such as the 9-PRT method, which actually uses more pulse repetition time and can be extended Speed ​​measurement range; the more pulse repetition time intervals used, the larger the scalable speed measurement range, but the more complex the algorithm, the lower the reliability

[0040] (4) Multi-pulse carrier frequency method: each group of pulses uses different carrier frequency combinations, and the same Doppler frequency shift can obtain different phase differences, thereby obtaining different maximum measurable speeds; the more available frequency bands, the more The extended speed measurement range is also larger, but due to the limited frequency band resources, the scalable speed measurement range of this method is also limited

[0042] However, regardless of multi-pulse repetition time, multi-carrier frequency, or a combination of the two, the ultimately scalable speed measurement range is limited. When the true speed exceeds the range that can be effectively resolved, the problem of speed folding (fuzzy) still exists , and the more the number of repetition periods used, the more the number of carrier frequency bands, the more complex the algorithm, and the worse the anti-interference ability

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