CN101387702A - Phase laser range finder and phase inspecting method thereof - Google Patents

Abstract

The invention discloses a phase type laser range finder and a phase detecting method thereof, belonging to the electronic measurement technical field. The phase type laser range finder comprises a signal sampling control module, a first signal amplifying filter module, a second signal amplifying filter module, a scale signal generation module, a laser modulation launching module, a light signal receiving detection module, a signal logarithmic converter, a power module and a display module. The phase detecting method comprises: selecting a system down sampling frequency, finding sampling data length, grouping sampling data, calculating phase shift and distance. The phase type laser range finder adopting the phase detection method can utilize a quartz crystal filter to filer the ranging signals, utilize continuous indirect scale frequency and down sampling technique, and combine sampling and signal processing functions on a chip, having simple structure, high measurement accuracy and low cost.

Description

A kind of phase type laser range finder and phase-detecting method thereof

Technical field

The present invention relates to a kind of laser range finder, relate in particular to a kind of phase type laser range finder and phase-detecting method thereof, belong to the electronic surveying field.

Background technology

Laser range finder, as contactless surveying instrument, fields such as remote sensing, precision measurement, engineering construction, safety monitoring and Based Intelligent Control have been widely used in, the phase type laser range finder is with its precision height, the little and portable characteristics of power, be applicable to civilian category, bigger market and application prospect are arranged.Ranging phase method is by measuring the phase shift that is produced behind the modulated light wave air-borne transmission, thereby tries to achieve the distance that light wave is passed by.Light wave phase place in communication process is constantly to change, and it is high more that modulation frequency is chosen, and the theoretical precision of range finding is just high more, but the realization difficulty of simultaneity factor is just big more.Laser ranging has two kinds of the direct modulation frequency mode of dispersion and continuous indirect modulation frequency modes, the direct modulation frequency mode of disperseing promptly is directly to provide the accurate measurement chi, the frequency of bigness scale chi is used for measuring, for reducing because of the accurate measurement chi, a series of problems that bigness scale chi frequency adjustment span is brought greatly, continuous indirect modulation frequency mode is generally adopted in range finding, the principle of continuous indirect modulation frequency mode is: when same distance is done the phase method measurement, the phase shift that two modulation frequencies are found range respectively poor equals to find range and the phase shift that obtains with the frequency difference of these two modulation frequencies.Be accompanied by the raising of modulation frequency, how guarantee that detected distance measuring signal quality becomes key issue, do not have good filtering performance, improving modulation frequency is nonsensical to measuring accuracy.Quartz-crystal filter has good bandpass filtering performance, pass band width is generally about 10KHz, but the model of having only less several centre frequencies, can't be as the bandpass filter that L, R, C form any adjusting centre frequency, have the problem of using coupling.

At present, phase type laser ranging phase-detecting method mainly contains down-sampled digital synchronous detection method, FFT (fast fourier transform) phase-detecting method, three kinds of pulsimeter numerical expression phase-detecting methods.Down-sampled digital synchronous detection method and FFT phase-detecting method phase-detecting precision are higher, the former requires modulation frequency generation sequential need and ADC (analog to digital converter) sampling time sequence strict synchronism and meets specific proportionate relationship, in the existing quartz-crystal filter, if do not add the mixing device, be difficult to find the model that to mate modulation frequency and ADC sample frequency simultaneously, therefore the filter quality of surveying the chi signal is not fine, directly influence accuracy of detection, in addition, system to the stability requirement of ADC device sampling time sequence also than higher; Latter FFT phase-detecting method is owing to need satisfy the shannon sampling thheorem, and the sample frequency height of ADC if will use low sample frequency to realize that the FFT phase-detecting need increase mixting circuit, realizes that cost is higher; Pulsimeter numerical expression phase-detecting method phase-detecting precision is not high.

Summary of the invention

The present invention proposes a kind of phase type laser range finder and phase-detecting method thereof in order well to use the good bandpass filtering performance of quartz-crystal filter on the phase type laser range finder.

A kind of phase type laser range finder, it comprises: the signal sampling processing and control module, the first signal amplification filtering module, secondary signal amplification filtering module, survey the chi signal generating module, the Laser Modulation transmitter module, light signal receives detection module, signal logarithmic converter module, power module, display module, wherein: the output termination of signal sampling processing and control module is surveyed the input end of chi signal generating module, survey the input end of the output termination Laser Modulation transmitter module of chi signal generating module, the input end of the output termination secondary signal amplification filtering module of Laser Modulation transmitter module, the Laser Modulation transmitter module also is provided with a Laser emission end, the input end of the output termination signal sampling processing and control module of secondary signal amplification filtering module, light signal receives the input end of the output termination signal logarithmic converter module of detection module, light signal receives detection module and also is provided with a laser pick-off end, the input end that output termination first signal of signal logarithmic converter module sends out filtration module big, the input end of the output termination signal sampling processing and control module of the first signal amplification filtering module, the input end of the shows signal output termination display module of signal sampling processing and control module, power module is given above-mentioned all module for power supply.

A kind of phase-detecting method based on this phase type laser range finder, its step is as follows:

Sample frequency f _AAdopt digital signal result be:

Q(K)＝aA?sin(2πfK/f _A+θ+φ)+DC (K＝0，1，2，3…)

Wherein: f is a modulation frequency; K is single sampling number; A is the attenuation coefficient that is produced by propagation in atmosphere and influence circuit; A is a shoot laser intensity amplitude; DC is a dc-bias, is a definite value; θ is the phase shift that electro-optical system structure and circuit transmission cause; φ is phase shift that light transmission the is caused value to 2 π complementation gained;

The phase-detecting method step is as follows:

A. the down-sampled frequency of selecting system:

ADC sample frequency f _A=f ₁-f ₂(f ₁F ₂), the used down-sampled frequency values of system just, wherein: the first modulation frequency f ₁With the second modulation frequency f ₂Be two continuous indirect modulation frequencies, must be respectively with individual signals amplification filtering module in the centre frequency of two quartz-crystal filters equate;

B. determine sampled data length:

Sampled data length k=3*2 ^b-1 (b=0,1,2,3...), also comprise sampled data length k=0 this point, wherein: the b value is chosen according to the processing power and the accuracy requirement of system;

C. sampled data grouping:

The sampling number certificate that two ADC module samples obtain is all carried out following grouping: the sampling number certificate is taken out every two data, reformulate three groups of new data, promptly two ADC modules adopt the sampling number certificate the 1st, 4,7 ... individual data are formed the first array Q respectively ₀With the second array Q ' ₀, the 2nd, 5,8 ... individual data are formed the 3rd array Q respectively ₁With the 4th array Q ' ₁, the 3rd, 6,9 ... individual data are formed the 5th array Q respectively ₂With the 6th array Q ' ₂

D. the calculating of phase shift:

The first modulation frequency f of system ₁With the second modulation frequency f ₂All carry out the calculating of following phase shift value: at first to the first array Q of detection signal circuit ₀, the 3rd array Q ₁, the 5th array Q ₂The second array Q ' with reference signal circuit ₀, the 4th array Q ' ₁, the 6th array Q ' ₂In the element summation of each array do binary shift right b position average calculating operation, these six arrays are converted into the first corresponding mean value A ₀, the 3rd mean value A ₁, the 5th mean value A ₂With the second mean value A ' ₀, the average A ' of Siping City ₁, the 6th mean value A ' ₂Then detection signal circuit mean value is following serial computing: A ₃=A ₁-A ₀, A ₄=A ₀-A ₂, A ₅=A ₁-A ₂, A ₆=A ₄-A ₃In like manner reference signal circuit mean value is following serial computing: A ' ₃=A ' ₁-A ' ₀, A ' ₄=A ' ₀-A ' ₂, A ' ₅=A ' ₁-A ' ₂, A ' ₆=A ' ₄-A ' ₃Calculate A at last ₇=A ₆+ A ' ₆, A ₈=A ' ₅-A ₅, again to A ₇/ A ₈Value do arctangent cp cp operation one time; Through twice as above computing, thereby obtain the first modulation frequency f ₁Under the value φ of first phase shift after to 2 π complementations ₁With the second modulation frequency f ₂Under the value φ of second phase shift after to 2 π complementations ₂

E. the calculating of distance value:

Value φ after first phase shift is to 2 π complementations ₁With the value φ of second phase shift after to 2 π complementations ₂In: if φ ₁φ ₂, the bigness scale chi frequency plot value of moving φ then ₃=φ ₁-φ ₂If φ ₁＜φ ₂, the bigness scale chi frequency plot value of moving φ then ₃=φ ₁+ 2 π-φ ₂Calculate bigness scale chi distance value $D_{}$ ${}_1=\frac{\mathrm{\&lambda;}}{2}\&CenterDot;\frac{{\mathrm{\&phi;}}_3}{2\mathrm{\&pi;}},$ It is rounded draw the first coverage value D ₁'; Calculate accurate measurement chi distance value again ${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="A200810155230E00091.png"\; state="\{\{state\}\}">D</figure-callout>}}_2=\frac{\mathrm{\&lambda;}}{2}\&CenterDot;\frac{{\mathrm{\&phi;}}_1}{2\mathrm{\&pi;}},$ It is got decimal place draw the second coverage value D ₂'; Then survey distance value D=D ₁'+D ₂', wherein: λ is an optical wavelength.

The present invention proposes a kind of phase type laser range finder system architecture, and be that the basis has proposed a kind of method for detecting phases with this structure, by using the method phase-detecting, system can carry out filtering to distance measuring signal with quartz-crystal filter; Native system adopts continuous indirect modulation frequency mode, and has used down-sampled technology, and sampling is integrated on the same chip with signal processing function, and system architecture is simple and easy, the measuring accuracy height, and cost is low.

Description of drawings

Fig. 1 is the integral module synoptic diagram of laser range finder of the present invention, number in the figure title: 1. signal sampling processing and control module, 2. the first signal amplification filtering module, 2 '. secondary signal amplification filtering module, 3. survey chi signal generating module, 4. Laser Modulation transmitter module, 5. light signal receives detection module, 6. signal logarithmic converter module, 7. power module, 8. display module.

Fig. 2 is the phase-detecting schematic flow sheet under the single modulation frequency of the present invention, and wherein: ADC0, ADC1 represent the employed sampling channel of signal sampling.

Specific embodiments

As shown in Figure 1, integral module of the present invention comprises that signal sampling processing and control module 1, the first signal amplification filtering module 2, secondary signal amplification filtering module 2 ', survey chi signal generating module 3, Laser Modulation transmitter module 4, light signal receive detection module 5, signal logarithmic converter module 6, power module 7, display module 8.At first survey chi signal generating module 3 and produce the first modulation frequency signal by 1 control of signal sampling processing and control module, laser tube in this signal amplitude modulated laser modulate emission module 4, the photoelectric monitor signal of laser tube is as the reference signal, after the 2 ' filtering of secondary signal amplification filtering module, by signal sampling processing and control module 1 sampling processing; Shoot laser is after the air borne reflection, receiving detection module 5 through light signal detects, produce detection signal, this signal entering signal logarithmic converter module 6 is carried out dynamic range of signals and is regulated, through 2 filtering of the first signal amplification filtering module, carry out signal sampling and processing again by signal sampling processing and control module 1; After reference signal and the comparison of detection signal detection result, detect the phase information under this modulation frequency.Survey chi signal generating module 3 by 1 control of signal sampling processing and control module again and produce the second modulation frequency signal, the process through same detects the phase information under this modulation frequency; At last, by mating the phase information that is detected under these two modulation frequencies, obtain ranging data, these data are sent display module 8, provide measurement result directly perceived.Power module 7 provides the power supply of each module of system.

As shown in Figure 2, be based on the phase-detecting method under the single modulation frequency of this laser range finder, its complete phase-detecting method is as follows:

Sample frequency f _AAdopt digital signal result be:

Q(K)＝aA?sin(2π?fK/f _A+θ+φ)+DC (K＝0，1，2，3…)

Wherein: f is a modulation frequency; K is single sampling number; A is the attenuation coefficient that is produced by propagation in atmosphere and influence circuit; A is a shoot laser intensity amplitude; DC is a dc-bias, is a definite value; θ is the phase shift that electro-optical system structure and circuit transmission cause; φ is phase shift that light transmission the is caused value to 2 π complementation gained;

The phase-detecting method step is as follows:

A. the down-sampled frequency of selecting system:

ADC sample frequency f _A=f ₁-f ₂(f ₁F ₂), the used down-sampled frequency values of system just, wherein: the first modulation frequency f ₁With the second modulation frequency f ₂Be two continuous indirect modulation frequencies, must be respectively with individual signals amplification filtering module in the centre frequency of two quartz-crystal filters equate;

B. determine sampled data length:

Sampled data length k=3*2 ^b-1 (b=0,1,2,3...), also comprise sampled data length k=0 this point, wherein: the b value is chosen according to the processing power and the accuracy requirement of system;

C. sampled data grouping:

The sampling number certificate that two ADC module samples obtain is all carried out following grouping: the sampling number certificate is taken out every two data, reformulate three groups of new data, promptly two ADC modules adopt the sampling number certificate the 1st, 4,7 ... individual data are formed the first array Q respectively ₀With the second array Q ' ₀, the 2nd, 5,8 ... individual data are formed the 3rd array Q respectively ₁With the 4th array Q ' ₁, the 3rd, 6,9 ... individual data are formed the 5th array Q respectively ₂With the 6th array Q ' ₂

D. the calculating of phase shift:

The first modulation frequency f of system ₁With the second modulation frequency f ₂All carry out the calculating of following phase shift value: at first to the first array Q of detection signal circuit ₀, the 3rd array Q ₁, the 5th array Q ₂The second array Q ' with reference signal circuit ₀, the 4th array Q ' ₁, the 6th array Q ' ₂In the element summation of each array do binary shift right b position average calculating operation, these six arrays are converted into the first corresponding mean value A ₀, the 3rd mean value A ₁, the 5th mean value A ₂With the second mean value A ' ₀, the average A ' of Siping City ₁, the 6th mean value A ' ₂Then detection signal circuit mean value is following serial computing: A ₃=A ₁-A ₀, A ₄=A ₀-A ₂, A ₅=A ₁-A ₂, A ₆=A ₄-A ₃In like manner reference signal circuit mean value is following serial computing: A ' ₃=A ' ₁-A ' ₀, A ' ₄=A ' ₀-A ' ₂, A ' ₅=A ' ₁-A ' ₂, A ' ₆=A ' ₄-A ' ₃Calculate A at last ₇=A ₆+ A ' ₆, A ₈=A ' ₅-A ₅, again to A ₇/ A ₈Value do arctangent cp cp operation one time; Through twice as above computing, thereby obtain the first modulation frequency f ₁Under the value φ of first phase shift after to 2 π complementations ₁With the second modulation frequency f ₂Under the value φ of second phase shift after to 2 π complementations ₂

E. the calculating of distance value:

Value φ after first phase shift is to 2 π complementations ₁With the value φ of second phase shift after to 2 π complementations ₂In: if φ ₁φ ₂, the bigness scale chi frequency plot value of moving φ then ₃=φ ₁-φ ₂If φ ₁＜φ ₂, the bigness scale chi frequency plot value of moving φ then ₃=φ ₁+ 2 π-φ ₂Calculate bigness scale chi distance value $D_{}$ ${}_1=\frac{\mathrm{\&lambda;}}{2}\&CenterDot;\frac{{\mathrm{\&phi;}}_3}{2\mathrm{\&pi;}},$ It is rounded draw the first coverage value D ₁'; Calculate accurate measurement chi distance value again ${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="A200810155230E00091.png"\; state="\{\{state\}\}">D</figure-callout>}}_2=\frac{\mathrm{\&lambda;}}{2}\&CenterDot;\frac{{\mathrm{\&phi;}}_1}{2\mathrm{\&pi;}},$ It is got decimal place draw the second coverage value D ₂'; Then survey distance value D=D ₁'+D ₂', wherein: λ is an optical wavelength.

The starting point of the present invention's design is to utilize the good band-pass filtering property of quartz-crystal filter to guarantee the precision of measuring.Under the prerequisite of not using the mixing device, modulation frequency is restricted to the passband central frequency of quartz-crystal filter, and native system quartz crystal filtration module has two passband central frequencies, with them as modulation frequency.There is two-way ADC sampling channel in system, has sampling hold circuit separately, works in the mode of down-sampled distance measuring signal.There is the two paths of signals path in system, is respectively detection signal path and reference signal path, has detection signal circuit and reference signal circuit accordingly, and system draws the phase shift that the laser air-borne transmission is produced by comparing this two paths of signals.System surveys chi signal generating module 3 and mainly comprises a DDS, control the sinewave modulation signal that produces different frequency by writing the control word mode, it has three kinds of mode of operations: one is the single-frequency pattern, two is direct translative mode, three is linear scan pattern, and the present invention uses direct translative mode, needs in advance two used modulation frequency correlation parameters to be programmed respectively to import in two registers of DDS inside, select different registers by writing control word, thereby produce different modulation frequency signals.System's Laser Modulation transmitter module 4 mainly comprises semiconductor laser tube and laser emitting light channel structure, and shoot laser is miniwatt two class laser, and exit end has collimation lens, and laser tube has the photoelectric monitor function.System's light signal receives detection module 5 and mainly comprises integrated operational amplifier, silicon PIN photoelectric diode, logarithmic amplifier, filter plate and light signal receiving light path structure, receiving front-end has a receiver lens, the narrowband optical signal that this module inspection center's frequency is identical with the shoot laser centre frequency.System signal sampling processing control module 1 mainly comprises a MCU and a keyboard.System power supply module 7 mainly comprises a direct current transducer, uses the alkaline AA battery of two joints as power supply.System's display module 8 mainly comprises a liquid-crystal controller, a LCDs.System further comprises a JTAG emulation and a debugging interface in the debug phase, and this interface can be dispeled in system after debugging is finished, so does not comprise this jtag interface in the actual product.

The principle of work of this phase type laser range finder is: the Enable Pin loading high level signal at power module enables it, to be stable 3.3V output by the input power source conversion that form of the alkaline AA battery of two joints, direct or with the power supply of dividing potential drop mode as each device of system; After treating that all power supplys of system and clock signal are all stable, be downloaded in the MCU in the signal sampling processing and control module 1 algorithm routine among the present invention and operation by the JTAG mouth, this moment, MCU was in the interrupt latency state, arrival etc. measured trigger pip, if also not having the range finding trigger pip after 5 minutes arrives, MCU sends out low level signal to power module, makes it to lose efficacy the shutoff system; In advance the correlation parameter of two modulation frequencies being programmed respectively imports in two registers surveying DDS inside in the chi signal generating module 3, and at this moment, what DDS waited for MCU writes the control word trigger pip, and no useful signal is exported; Laser Modulation transmitter module 4, light signal receive detection module 5, two signal amplification filtering modules 2 and 2 ', signal logarithmic converter modules 6 all will be found range trigger pip as enable signal; Just in running order after display module 8 powers on, the output ranging data of wait MCU.

When the range finding trigger pip arrives, MCU enters interrupt service routine, sends out to write control word trigger pip notice DDS and open direct translative mode function, and writes control word and select to produce first modulation frequency signal to DDS, and afterwards, MCU carries out a short time and waits for; Meanwhile, Laser Modulation transmitter module 4, light signal receive detection module 5, two signal amplification filtering modules 2 and 2 ', signal logarithmic converter modules 6 enable, and reach steady-working state in waiting in the MCU short time; The short time wait finishes, MCU starts TIMER3 (clock on the sheet), send the sampling triggering synchronous signal of the clock signal of certain fixed frequency as two ADC modules on the MCU sheet, when sampled data reaches certain power of 2 of 3 times, MCU sends out and writes control word signalisation DDS and open direct translative mode function, and writes control word and select to produce second modulation frequency signal to DDS; After this, MCU no longer waits for, when the ADC sampled data reaches certain power of 2 of 6 times, MCU enters the phase-detecting algorithm process, and sends that a control signal makes Laser Modulation transmitter module 4, light signal receive detection module 5, two signal amplification filtering modules 2 and 2 ', signal logarithmic converter modules 6 all lost efficacy; When the phase-detecting algorithm process finishes, MCU send the range finding result to display module, and reenters the interrupt latency state, wait for the arrival of next range finding trigger pip, do not arrive that MCU sends out low level signal to power module if also there is the range finding trigger pip after 5 minutes, make it to lose efficacy the shutoff system.

Claims (4)

1, a kind of phase type laser range finder, it is characterized in that: comprise signal sampling processing and control module (1), the first signal amplification filtering module (2), secondary signal amplification filtering module (2 '), survey chi signal generating module (3), Laser Modulation transmitter module (4), light signal receives detection module (5), signal logarithmic converter module (6), power module (7), display module (8), wherein: the output termination of signal sampling processing and control module (1) is surveyed the input end of chi signal generating module (3), survey the input end of the output termination Laser Modulation transmitter module (4) of chi signal generating module (3), the input end of the output termination secondary signal amplification filtering module (2 ') of Laser Modulation transmitter module (4), Laser Modulation transmitter module (4) also is provided with a Laser emission end, the input end of the output termination signal sampling processing and control module (1) of secondary signal amplification filtering module (2 '), light signal receives the input end of the output termination signal logarithmic converter module (6) of detection module (5), light signal receives detection module (5) and also is provided with a laser pick-off end, the input end that output termination first signal of signal logarithmic converter module (6) sends out filtration module (2) big, the input end of the output termination signal sampling processing and control module (1) of the first signal amplification filtering module (2), the input end of the shows signal output termination display module (8) of signal sampling processing and control module (1), power module (7) is given above-mentioned all module for power supply.

2, a kind of phase type laser range finder according to claim 1 is characterized in that the centre frequency of the first signal amplification filtering module (2) and secondary signal amplification filtering module (2 ') is identical, and enlargement factor is adjustable.

3, a kind of phase type laser range finder according to claim 1, needing in the signal sampling processing and control module (1) it is characterized in that the independent ADC sampling channel in integrated n road, and its sampling resolution is n ' position, and wherein: n is the natural number greater than 1, and n ' is the natural number greater than 11.

4, a kind of phase-detecting method based on the described phase type laser range finder of claim 1 is characterized in that: sample frequency f _AAdopt digital signal result be:

Q(K)＝aA?sin(2πfK/f _A+θ+φ)+DC (K＝0，1，2，3…)

Wherein: f is a modulation frequency; K is single sampling number; A is the attenuation coefficient that is produced by propagation in atmosphere and influence circuit; A is a shoot laser intensity amplitude; DC is a dc-bias, is a definite value; θ is the phase shift that electro-optical system structure and circuit transmission cause; φ is phase shift that light transmission the is caused value to 2 π complementation gained;

The phase-detecting method step is as follows:

A. the down-sampled frequency of selecting system:

ADC sample frequency f _A=f ₁-f ₂(f ₁F ₂), the used down-sampled frequency values of system just, wherein: the first modulation frequency f ₁With the second modulation frequency f ₂Be two continuous indirect modulation frequencies, must be respectively with individual signals amplification filtering module in the centre frequency of two quartz-crystal filters equate;

B. determine sampled data length:

Sampled data length k=3*2 ^b-1 (b=0,1,2,3...), also comprise sampled data length k=0 this point, wherein: the b value is chosen according to the processing power and the accuracy requirement of system;

C. sampled data grouping:

The sampling number certificate that two ADC module samples obtain is all carried out following grouping: the sampling number certificate is taken out every two data, reformulate three groups of new data, promptly two ADC modules adopt the sampling number certificate the 1st, 4,7 ... individual data are formed the first array Q respectively ₀With the second array Q ' ₀, the 2nd, 5,8 ... individual data are formed the 3rd array Q respectively ₁With the 4th array Q ' ₁, the 3rd, 6,9 ... individual data are formed the 5th array Q respectively ₂With the 6th array Q ' ₂

D. the calculating of phase shift:

The first modulation frequency f of system ₁With the second modulation frequency f ₂All carry out the calculating of following phase shift value: at first to the first array Q of detection signal circuit ₀, the 3rd array Q ₁, the 5th array Q ₂The second array Q ' with reference signal circuit ₀, the 4th array Q ' ₁, the 6th array Q ' ₂In the element summation of each array do binary shift right b position average calculating operation, these six arrays are converted into the first corresponding mean value A ₀, the 3rd mean value A ₁, the 5th mean value A ₂With the second mean value A ' ₀, the average A ' of Siping City ₁, the 6th mean value A ' ₂Then detection signal circuit mean value is following serial computing: A ₃=A ₁-A ₀, A ₄=A ₀-A ₂, A ₅=A ₁-A ₂, A ₆=A ₄-A ₃In like manner reference signal circuit mean value is following serial computing: A ' ₃=A ' ₁-A ' ₀, A ' ₄=A ' ₀-A ' ₂, A ' ₅=A ' ₁-A ' ₂, A ' ₆=A ' ₄-A ' ₃Calculate A at last ₇=A ₆+ A ' ₆, A ₈=A ' ₅-A ₅, again to A ₇/ A ₈Value do arctangent cp cp operation one time; Through twice as above computing, thereby obtain the first modulation frequency f ₁Under the value φ of first phase shift after to 2 π complementations ₁With the second modulation frequency f ₂Under the value φ of second phase shift after to 2 π complementations ₂

E. the calculating of distance value:

Value φ after first phase shift is to 2 π complementations ₁With the value φ of second phase shift after to 2 π complementations ₂In: if φ ₁φ ₂, the bigness scale chi frequency plot value of moving φ then ₃=φ ₁-φ ₂If φ ₁＜φ ₂, the bigness scale chi frequency plot value of moving φ then ₃=φ ₁+ 2 π-φ ₂Calculate bigness scale chi distance value $D_1=\frac{\mathrm{\&lambda;}}{2}\&CenterDot;\frac{{\mathrm{\&phi;}}_3}{2\mathrm{\&pi;}},$ It is rounded draw the first coverage value D ₁'; Calculate accurate measurement chi distance value again $D_2=\frac{\mathrm{\&lambda;}}{2}\&CenterDot;\frac{{\mathrm{\&phi;}}_1}{2\mathrm{\&pi;}},$ It is got decimal place draw the second coverage value D ₂'; Then survey distance value D=D ₁'+D ₂', wherein: λ is an optical wavelength.

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