CN102679948A - Method for eliminating aliasing of high-repeat-frequency laser ranging pulses - Google Patents

Abstract

The invention discloses a method for eliminating aliasing of high-repeat-frequency laser ranging pulses. The method can be used for expanding an action range of a high-repeat-frequency laser range finder. By the aid of a gating switch, dominant-wave pulses at different positions in a high-repeat-frequency dominant-wave pulse sequence enter different time measuring circuits and are used for triggering a timer for measuring time intervals; a shield time interval is set according to a range finding scope of the dominant waves after the different time measuring circuits receive the dominant waves, and echo other than the dominant waves is shielded; the action range which can be expanded by the method is relevant to laser repeat frequency, the theoretical maximum of the expanded action range is the integer multiples of the laser repeat frequency, and the multiples are equal to the number of branches of laser transmitting pulses; and the method for eliminating aliasing of high-repeat-frequency laser ranging pulses not only can be implemented in a hardware mode, but also can be implemented in a software mode, the full-waveform recording laser transmitting and receiving range finder is used, and analysis processing is carried by a software method.

Description

A kind of method of eliminating high Repetition Frequency Laser range finding pulse aliasing

Technical field:

The present invention relates to a kind of method of eliminating high Repetition Frequency Laser range finding pulse aliasing, can be used for expanding the reach of the high Repetition Frequency Laser stadimeter that uses traditional distance measuring method.

Background technology:

Traditional pulse laser laser welder adopts the time interval between record emission laser pulse (being defined as main ripple) and the laser return pulse (being defined as echo) to carry out range observation.

Like accompanying drawing 1, can obtain distance measurement value through the time interval of writing down main ripple and echo, timekeeping circuit can write down one or several echoes after the main ripple.

Above-mentioned distance measuring method did not allow to occur 2 or above main ripple before echo detects echo, person's timekeeping circuit can not measured echo last main ripple before.Therefore, the maximum time that this distance measuring method can be measured in theory that is to say that at interval less than the interval between the emitted laser master ripple its maximum operating range is limited to the Laser emission frequency, and frequency is high more, and operating distance is more little.When the transmission frequency of laser was increasingly high, when the operating distance of requirement can not reduce again, this contradiction was just more outstanding.

Therefore, the present invention has designed a kind of method of eliminating high Repetition Frequency Laser range finding pulse aliasing, lets the transmission frequency of laser no longer be the absolute factor of restriction distance.

Summary of the invention:

The purpose of this invention is to provide a kind of method of eliminating high Repetition Frequency Laser range finding pulse aliasing, the technical solution problem? Let the transmission frequency of laser no longer be the absolute factor of restriction distance.

The present invention adopts hardware plan to realize.Adopt hard-wired counting scheme mainly to comprise: the multi-channel gating switch between lasing light emitter and the timekeeping circuit; N timekeeping circuit, finding range that N expands as required and formula (2) calculate; Each timekeeping circuit need shield temporal logic.

1. gating switch

The effect of gating switch is, different timekeeping circuits is advanced in the continuous pulse in the high frequency master ripple trigger pulse sequence that realizes lasing light emitter is sent gating respectively, thereby reduces the frequency of the main wave impulse that each timekeeping circuit receives, shown in accompanying drawing 2.Because for each timekeeping circuit, before the echo that receives the main ripple correspondence that triggers this timekeeping circuit, do not allow that other main ripple triggers this timekeeping circuit.Therefore, its maximum limit range finding distance is its main wave impulse frequency that receives.Through gating switch, reduced the frequency of the main wave impulse that each timekeeping circuit receives, thereby increased the finding range of each timekeeping circuit.

2. timekeeping circuit

Timekeeping circuit is identical with traditional laser range finder timekeeping circuit, and after receiving main ripple trigger pip, timer picks up counting; After receiving an echo, timekeeping circuit stops timing.Bring the time in the timer into formula (1) and can calculate the distance that this main ripple measures.

3. shielding temporal logic

For each timekeeping circuit, its main ripple that receives is the part of whole main ripples of sending of lasing light emitter.But because all shared sounders of timekeeping circuit, therefore, each timekeeping circuit can receive all echoes.Shown in accompanying drawing 2, timekeeping circuit 1 timer after receiving main wave impulse 3 picks up counting, if one shielding period is not set, then timers stop timing after receiving echo 2.Obviously, the distance of calculating according to the value of timer is wrong.If according to the finding range of timekeeping circuit, after receiving main ripple trigger pip, is set one shielding period, shown in accompanying drawing 2, masked echo 2 after, correctly received echo 3.The shielding temporal logic can be set in the shielding time interval, and timer does not respond any echoed signal.

5. advantage of the present invention

The present invention only needs that traditional stadimeter is carried out simple modifications and can realize that main the improvement is to have increased main ripple gating switch, and a plurality of timekeeping circuits are provided with one shielding period to each test circuit after receiving main ripple trigger pip.Therefore the present invention is simple in structure, is easy to realize.

Description of drawings:

Fig. 1 is traditional pulsed laser ranging mode synoptic diagram.

Fig. 2 is for being schematic diagram of the present invention.

Embodiment:

Provide better examples of implementation of the present invention according to accompanying drawing 2 below, so that further provide ins and outs of the present invention, enable architectural feature of the present invention and functional characteristics are described better, but be not to be used for limiting protection scope of the present invention.

System hardware constitutes:

Lasing light emitter, lasing light emitter are each initiatively essential elements of stadimeter, and the index of paying close attention to here is high repetition frequency.Repetition frequency is high more, and obtainable range data is many more in the unit interval.For traditional stadimeter, high repetition frequency has also limited the scope of range finding simultaneously.

Gating switch, with the continuous pulse gate in the main wave train in different timekeeping circuits.

Timekeeping circuit is used to measure the time between main ripple and the echo, thereby calculates measuring distance.

Specific embodiments of the present invention is following:

1. consult accompanying drawing 2, before the 2nd main ripple sent, echo was not also returned; Therefore, if directly signal is sent into first timekeeping circuit, will measure the time interval of the 2nd main ripple and the 1st echo; Laser pulse occurs and measure the situation of aliasing, calculate wrong distance measurement value.

2. in accompanying drawing 2, main ripple has been divided into 2 the tunnel, passes through gating switch respectively; The 1 the tunnel allows through main ripple 1, main ripple 3, main ripple 5 etc., the 2 the tunnel allows through main ripple 2, main ripple 4, main ripple 6 etc., then between the main ripple that will measure and echo, has only kept one tunnel correct main ripple; See accompanying drawing 2, the 1st main ripple can directly measure right value when measuring afterwards along separate routes, two echoes can occur after the 2nd the main ripple; Echo 2 is only correct echoed signal, and therefore, range for measuring is provided with the time interval of one section shielding after main ripple as requested; Shown in empty frame among the figure, so just can eliminate the situation of high Repetition Frequency Laser impulsive measurement aliasing, obtain correct distance measurement value; The scope of expansion this moment is 2 times a laser pulse interval, and expansion is more times if desired, then can main ripple be divided into more multichannel.

Claims (2)

1. method of eliminating high Repetition Frequency Laser range finding pulse aliasing; It is characterized in that: switching gate control is carried out in the Laser emission pulse, got into different timekeeping circuits successively, simultaneously; For each timekeeping circuit; After receiving main ripple trigger pip, need be set one shielding period according to its finding range, mask the echoed signal that does not belong to the main ripple correspondence that triggers this timekeeping circuit; If the timekeeping circuit number is N, i.e. Laser emission pulse is by number along separate routes, and laser pulse repetition frequency is f.After then sending the first main ripple, this main ripple can trigger the timer of first via metering circuit, through gating switch; The N-1 of back main ripple can not trigger the timer of first via metering circuit, but triggers the timer of remaining N-1 drive test amount circuit respectively, for first via metering circuit; After receiving main ripple trigger pip,, be set one period shielding time interval according to the distance range of its measurement; Mask and do not belong to the corresponding echo of main ripple that triggers this metering circuit; Therefore, trigger the main ripple of first via metering circuit and the maximum time interval of corresponding echo and can reach N τ, τ=1/f; Laser pulse repetition frequency is f, and the light velocity is c, and the corresponding ultimate range D2 that can measure is:

$D2=\frac{\mathrm{Nc}}{2f}---\left(1\right)$

2. a kind of method of eliminating high Repetition Frequency Laser range finding pulse aliasing according to claim 1; It is characterized in that: described method not only can realize with hardware mode, can also in full waveform recording is launched laser and the stadimeter that receives laser, realize through software mode.

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