CN101149264A - Resonance type optical fiber peg-top signal detection method and device based on coordinate rotation digital computer algorithm - Google Patents
Resonance type optical fiber peg-top signal detection method and device based on coordinate rotation digital computer algorithm Download PDFInfo
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Abstract
The invention discloses a resonant fibre-optic gyro signal detection method and device based on the coordinate rotary digital computer algorithm. The detection method includes the modulation signal production and the signal demodulation method, which are all reached by the phase bit/scope switch module based on the coordinate rotary digital computer algorithm. The detection device includes the laser, the coupler, the phase bit modulator, the fibre-optic ringer, the photoelectrical detector, the present programme array chip, the digital/module switcher, the sample collecting channel, the reactive circuit and the signal output channel. The invention can reach the two circuits of the modulation signal production, demodulation and treatment by using the coordinate rotary digital computer algorithm; the scope, phase bit and frequency is dispatched by the programme, which is benefit for the detection system stable and assembly; the algorithm is determined by the iterative times and data word length; the fibre-optic ringer can avoid the light wave in fibre-optic back to the laser and influence the laser stable.
Description
Technical Field
The invention relates to a resonance type optical fiber gyro signal detection method and device based on a coordinate rotation digital computer algorithm.
Background
A resonant cavity Fiber Optic Gyro (R-FOG) is an inertial sensing device which utilizes the optical Sagnac effect to realize high-precision rotation detection. Since the Sagnac effect is a very weak effect, signal modulation and detection techniques have a very important position in systems. A commonly used detection circuit consists of a modulation signal generator and an analog demodulation signal. Compared with an analog detection system, the digital detection system has high stability and flexible design, and can effectively inhibit drift noise caused by 1/f noise, temperature and the like.
The key of the Direct Digital Frequency Synthesis (DDS) technology is the phase/amplitude conversion part, and commonly used methods include a Memory (Read-Only Memory, ROM) look-up table method, a taylor series method, and a Coordinate Rotation Digital Computer (CORDIC) algorithm. The capacity of the ROM table required by the ROM table lookup method increases exponentially with the increase of the precision requirement, and is not easy to be implemented in a Field Programmable Gate Array (FPGA). With the increasing level of integrated circuits, high precision frequency synthesis techniques can replace the ROM look-up table structure with real-time calculations. The taylor series method is also not easy to implement in FPGAs due to the large number of multiplication operations. The coordinate rotation digital computer algorithm is proposed by J.Volder in 1959, can complete high-precision phase-amplitude conversion through addition/subtraction and shift operation, and is very suitable for being realized in FPGA.
Aiming at the R-FOG system, a full digital signal detection method based on a coordinate rotation digital computer algorithm is provided. The generation of modulation signals, the synchronous demodulation of the signals and the digital signal processing can be simultaneously realized through a single-chip field programmable gate array chip, so that the R-FOG detection system is more stable and flexible.
Disclosure of Invention
The invention aims to provide a resonant mode fiber-optic gyroscope signal detection method and device based on a coordinate rotation digital computer algorithm. The modulation signal generation, the synchronous demodulation of the signal and the signal processing based on the coordinate rotation digital computer algorithm can be realized on a single-chip field programmable gate array chip, which is beneficial to the integration of a detection system and improves the precision and the stability of a detection circuit.
The resonance type optical fiber gyro signal detection method based on the coordinate rotation digital computer algorithm comprises a modulation signal generation method and a modulation signal demodulation method, wherein the two parts are as follows:
the generation method of the modulation signal comprises the following steps: under clock control, one of the field programmable gate array chipsThe frequency control register controls the frequency of the generated sine wave; the frequency control register is used as the input of a phase accumulator, the phase value output by the phase accumulator is used as the input phase quantity z of a phase/amplitude conversion module 0 ， z 0 Is the phase quantity for which the trigonometric value needs to be calculated; input initial vector coordinate value x of phase/amplitude conversion module 0 Set to a certain value, y 0 Set to 0, output x of the phase/amplitude conversion module N And y N Giving the input phase quantities z, respectively 0 The sine and cosine function values are used for generating sine wave voltage signals as modulation signals through a digital-to-analog converter;
the demodulation method of the modulation signal comprises the following steps: under the control of a clock, a phase control register in the field programmable gate array chip controls the phase difference between the modulation signal and the demodulated signal; the output of the phase accumulator in the phase control register and the modulation signal generating method is used as two input signals of an adder, and the phase value output by the adder is used as the input phase quantity z of a phase/amplitude conversion module 0 ，z 0 Is the phase quantity for which the trigonometric value needs to be calculated; sampling a signal containing a frequency component of a modulated signal by an analog/digital converter, wherein the sampled value is used as an input initial vector coordinate value x of a phase/amplitude conversion module 0 ，y 0 Is arranged as0; output x of phase/amplitude conversion module N The sine wave synchronous amplitude demodulation signal value is given through a low-pass filter, and the voltage demodulation signal is given through a digital/analog converter.
The phase/amplitude conversion module is as follows: the process of phase/amplitude conversion is achieved by a series of iterations of sub-angle rotation operations; the input parameter of the phase/amplitude conversion module is the phase quantity z 0 Initial vector coordinate value x 0 And y 0 (ii) a Will y 0 Set to 0, the output x of the phase/amplitude conversion module when the number of iterations N of its sub-angle rotation tends to infinity N And y N Respectively tend to x 0 ·sin(z 0 ) And x 0 ·cos(z 0 )，z N Tending to 0.
The iteration of the series of sub-angle rotation operations is as follows: the sub-angular rotation operation can be expressed as
Wherein x is j 、y j And z j As input variable for the sub-angle rotation operation, x j+1 、y j+1 And z j+1 The relational expression is the output variable of the sub-angle rotation operation and is realized by adding/subtracting and shifting in a field programmable gate array chip;
n is the total number of iterative operations, y 0 ＝0，z 0 Is the angle value for which the trigonometric value is to be calculated; when z is j > 0 or z j When is less than 0, delta j Respectively taking +1 and-1; a series of sub-angular rotation operationsThe order of the iterations is j =0,1,2,3.
A laser in the signal detection device of the resonant fiber-optic gyroscope based on the coordinate rotation digital computer algorithm is connected with a first coupler, a first phase modulator, a first fiber-optic circulator, a second coupler, a second fiber-optic circulator, a second phase modulator and a first coupler; the first phase modulator is connected with the first digital/analog converter; the second phase modulator is connected with the second digital-to-analog converter; the first optical fiber circulator is connected with the first photoelectric detector, the first signal sampling channel and the first analog-to-digital converter; the second optical fiber circulator is connected with the second photoelectric detector, the second signal sampling channel and the second analog-digital converter; the second coupler is connected with the optical fiber resonance ring; the third D/A converter is connected with the feedback circuit and the laser; the fourth digital/analog converter is connected with the gyro signal output channel; the field programmable gate array chip is respectively connected with the first digital-to-analog converter, the second digital-to-analog converter, the third digital-to-analog converter, the fourth digital-to-analog converter, the first analog-to-digital converter and the second analog-to-digital converter.
The circuit of the signal sampling channel is as follows: the positive input end of the first operational amplifier is used as a signal input end, the negative input end of the first operational amplifier is connected with the output end of the first operational amplifier, and the output end of the first operational amplifier is connected with one end of the first capacitor; the other end of the first capacitor is connected with one end of the first resistor and one end of the second resistor, and the other end of the first resistor is grounded; the positive input end of the second operational amplifier is connected with the other end of the second resistor, the negative input end of the second operational amplifier is connected with one end of the third resistor and one end of the fourth resistor, the output end of the second operational amplifier is connected with the other end of the fourth resistor and one end of the second capacitor, and the other end of the third resistor is grounded; the other end of the second capacitor is connected with one end of a fifth resistor and one end of a third capacitor, the other end of the third capacitor is connected with one end of a sixth resistor and the positive input end of a third operational amplifier, and the other end of the sixth resistor is grounded; the negative input end of the third operational amplifier is connected with one end of the seventh resistor and one end of the eighth resistor, the output end of the third operational amplifier is connected with the other end of the fifth resistor, the other end of the eighth resistor and one end of the ninth resistor, and the other end of the seventh resistor is grounded; the other end of the ninth resistor is connected with one end of the tenth resistor and one end of the fourth capacitor; the positive input end of the fourth operational amplifier is connected with the other end of the tenth resistor and one end of the fifth capacitor, the negative input end of the fourth operational amplifier is connected with one end of the eleventh resistor and one end of the twelfth resistor, the output end of the fourth operational amplifier is connected with the other end of the fourth capacitor and the other end of the twelfth resistor, and the other end of the eleventh resistor and the other end of the fifth capacitor are grounded.
The feedback circuit comprises the following circuits: one end of a thirteenth resistor is used as an input end, and the other end of the thirteenth resistor is connected with one end of a sixth capacitor and one end of a fourteenth resistor; the positive input end of the fifth operational amplifier is connected with the other end of the fourteenth resistor and one end of the seventh capacitor, the negative input end of the fifth operational amplifier is connected with one end of the fifteenth resistor and one end of the sixteenth resistor, the output end of the fifth operational amplifier is connected with the other end of the sixth capacitor, the other end of the sixteenth resistor and one end of the seventeenth resistor, and the other end of the fifteenth resistor and the other end of the seventh capacitor are grounded; the positive input end of the sixth operational amplifier is connected with one end of an eighteenth resistor, the negative input end of the sixth operational amplifier is connected with the other end of the seventeenth resistor and one end of a nineteenth resistor, the output end of the sixth operational amplifier is connected with the other end of the nineteenth resistor and one end of a twenty-second resistor, and the other end of the eighteenth resistor is grounded; the positive input end of the seventh operational amplifier is connected with one end of the twenty-first resistor, the negative input end of the seventh operational amplifier is connected with the other end of the twenty-second resistor, one end of the twenty-third resistor and one end of the twenty-fifth resistor, the output end of the seventh operational amplifier is connected with the other end of the twenty-fifth resistor, and the other end of the twenty-first resistor is grounded; the other end of the twenty-third resistor is connected with one end of the twentieth resistor and one end of the twenty-fourth resistor, the other end of the twentieth resistor is connected with the power supply, and the other end of the twenty-fourth resistor is grounded.
The gyro signal output channel circuit is as follows: one end of a twenty-sixth resistor is used as an input end, and the other end of the twenty-sixth resistor is connected with one end of an eighth capacitor and one end of a twenty-seventh resistor; the positive input end of the eighth operational amplifier is connected with the other end of the twenty-seventh resistor and one end of the ninth capacitor, the negative input end of the eighth operational amplifier is connected with one end of the twenty-eighth resistor and one end of the twenty-ninth resistor, the output end of the eighth operational amplifier is connected with the other end of the eighth capacitor and the other end of the twenty-ninth resistor, and the other end of the ninth capacitor and the other end of the twenty-eighth resistor are grounded.
The invention has the following beneficial effects:
1) The invention is based on the coordinate rotation digital computer algorithm, realizes the generation and synchronous demodulation of sine wave modulation signals through a field programmable gate array chip, the system precision is determined by the iteration times and the data word length in the algorithm, and the high precision can be realized;
2) The invention can flexibly configure the amplitude, phase position and frequency of a modulation signal on line in a field programmable gate array chip;
3) According to the invention, the generation, synchronous demodulation and signal processing of two paths of modulation signals are realized through a single-chip field programmable gate array chip, and the stability and integration of a resonant fiber-optic gyroscope detection system are facilitated;
4) The invention adopts the optical fiber ring resonator, and can prevent the light wave in the optical fiber ring resonator from returning to the laser, thereby influencing the stability of the laser.
Drawings
FIG. 1 is a structural diagram of a resonant fiber optic gyroscope system based on a coordinate rotation digital computer algorithm;
FIG. 2 is a schematic diagram of a CMD algorithm;
FIG. 3 is a block diagram of a counterclockwise optical path signal modulation and demodulation system;
FIG. 4 is a block diagram of a signal sampling channel;
FIG. 5 is a block diagram of a feedback circuit for tuning the frequency of the laser output light;
FIG. 6 is a block diagram of a gyro signal output channel;
in the figure: the device comprises a laser 1, a feedback circuit 2, a first coupler 3, a first phase modulator 4, a first digital-to-analog converter 5, a second digital-to-analog converter 6, a second phase modulator 7, a third digital-to-analog converter 8, a field programmable gate array chip 9, a fourth digital-to-analog converter 10, a first analog-to-digital converter 11, a second analog-to-digital converter 12, a gyro signal output channel 13, a first signal sampling channel 14, a second signal sampling channel 15, a first optical fiber circulator 16, a first photodetector 17, a second photodetector 18, a second optical fiber circulator 19, a second coupler 20 and an optical fiber resonant ring 21.
Detailed Description
As shown in fig. 1, a laser 1 in a signal detection device of a resonant fiber-optic gyroscope based on a coordinate rotation digital computer algorithm is connected with a first coupler 3, a first phase modulator 4, a first fiber-optic circulator 16, a second coupler 20, a second fiber-optic circulator 19, a second phase modulator 7 and the first coupler 3; the first phase modulator 4 is connected with a first digital/analog converter 5; the second phase modulator 7 is connected with the second digital/analog converter 6; the first optical fiber circulator 16 is connected with the first photoelectric detector 17, the first signal sampling channel 14 and the first analog/digital converter 11; the second optical fiber circulator 19 is connected with the second photoelectric detector 18, the second signal sampling channel 15 and the second analog/digital converter 12; the second coupler 20 is connected with the fiber resonance ring 21; the third D/A converter 8 is connected with the feedback circuit 2 and the laser 1; the fourth digital/analog converter 10 is connected with a gyro signal output channel 13; the field programmable gate array chip 9 is connected to the first digital-to-analog converter 5, the second digital-to-analog converter 6, the third digital-to-analog converter 8, the fourth digital-to-analog converter 10, the first analog-to-digital converter 11, and the second analog-to-digital converter 12, respectively.
Laser light emitted by a laser 1 is divided into two beams by a 50% coupler 3, the two beams are respectively modulated by Phase Modulators (PM) 4 and 7, and then coupled into a Fiber Resonance Ring (FRR) by a Fiber coupler 20 to form two resonant beams of Counter-Clockwise (CCW) and Clockwise (CW) light, which are respectively coupled to photodetectors 18 and 17 by Fiber circulators 19 and 16; the signal from the photodetector 18 is sent to the FPGA chip 9 by the high-speed A/D converter 12 after passing through the signal sampling channel 15, and the FPGA chip demodulates and extracts the deviation of the resonant frequency to control the output light frequency of the laser, so that the laser frequency is locked at the resonant point of the CCW light path; the signal from the photoelectric detector 17 is sent to the field programmable gate array chip 9 by the high-speed A/D converter 11 after passing through the signal sampling channel 14, and the gyroscope open-loop angular velocity signal is given out after passing through the high-speed A/D converter 10 and the gyroscope signal output channel 13 after being demodulated by the field programmable gate array chip.
The resonance type optical fiber gyro signal detection method based on the coordinate rotation digital computer algorithm comprises a modulation signal generation method and a modulation signal demodulation method, wherein the two parts are as follows:
fig. 2 shows a block diagram of a counterclockwise optical path signal modulation and demodulation system. The dotted line block diagram represents an FPGA chip, generates a sine wave modulation signal, performs phase modulation on the light wave by driving a phase modulator, and simultaneously performs synchronous demodulation on an output signal of a photoelectric detector.
The generation method of the modulation signal comprises the following steps: the sine wave signal is generated by an accumulator and a phase/amplitude conversion module of the CORDIC algorithm. Under the control of a clock, a Frequency Control Word (FCW) register in the field programmable gate array chip controls the frequency of the generated sine wave; the frequency control register serves as an input to a phase accumulator,the phase value output by the phase accumulator is used as the input phase quantity z of a phase/amplitude conversion module 0 ，z 0 Is the phase quantity for which the trigonometric value needs to be calculated; input initial vector coordinate value x of phase/amplitude conversion module 0 Set to a certain value, y 0 Set to 0 when the output x of the phase/amplitude conversion block N And y N Giving the input phase quantities z, respectively 0 Sine and cosine function values of, output x N Generating a sine wave voltage signal as a modulation signal through a digital-to-analog converter;
the demodulation method of the modulation signal comprises the following steps: under the control of a clock, a Phase Control Word (PCW) register in the field programmable gate array chip controls the phase difference between a modulation signal and a demodulated signal; the output of the phase accumulator in the phase control register and the modulation signal generating method is used as two input signals of an adder, and the phase value output by the adder is used as the input phase quantity z of a phase/amplitude conversion module 0 ，z 0 Is the phase quantity of the trigonometric function value to be calculated; sampling a signal containing a frequency component of a modulated signal by an analog/digital converter, wherein the sampling value is used as an input initial vector coordinate value x of a phase/amplitude conversion module 0 ，y 0 Set to 0; output x of phase/amplitude conversion module N The sine wave synchronous amplitude demodulation signal value is given through a Low Pass Filter (LPF), and the voltage demodulation signal is obtained through a digital/analog converter. The voltage demodulation signal is used for tuning the output optical frequency of the laser through a feedback circuit (FBC) so that the laser frequency is locked on the resonant frequency of the CCW optical path.
The phase/amplitude conversion module is as follows: the process of phase/amplitude conversion is achieved by a series of iterations of sub-angle rotation operations; the input parameter of the phase/amplitude conversion module is the phase quantity z 0 Initial vector coordinate value x 0 And y 0 (ii) a Will y 0 Set to 0, the phase/amplitude tends to be infinite when its number of iterations N of the sub-angle rotation operation tends to be infiniteOutput x of the conversion module N And y N Respectively tend to x 0 ·sin(z 0 ) And x 0 ·cos(z 0 )，z N Tending to 0. Thereby effecting phase/amplitude conversion.
The iteration of the series of sub-angle rotation operations is as follows:
the cordic has two modes of rotation and orientation. The basic concept of rotation pattern is to rotate the unit vector on the x-axis through a series of sub-angles by theta j (j is an integer) to a predetermined angle. Obtaining sine value sin theta and cosine value cos theta through N times of sub-angle rotation operations, wherein theta is theta of all sub-angles j And (4) summing.
FIG. 3 is a schematic diagram of the principle of the cordic algorithm, vector V j (x j ，y j ) Through a sub-angle theta j The rotation operation yields a vector V j+1 (x j+1 ，y j+1 ) The relationship can be expressed as:
in order to easily realize the operation of the above formula by simple addition/subtraction and shift operation in FPGA, the rotator angle theta j Setting as follows:
wherein, delta j Taking +1 or-1. After N sub-angular rotations, the correction factor K is defined as:
pre-correcting the initial unit vector by K to V 0 (K, 0) the amplitude amplification factor cos θ in each sub-angle rotation operation in the formula (1) can be avoided j . The sub-angle rotation operation of the CORDIC algorithm is thus expressed as:
wherein x is 0 ＝K，y 0 ＝0，z 0 Is an angle theta predetermined for calculating sine and cosine values, when z is j > 0 or z j When < 0, delta j Respectively taken as +1 and-1. When the number of sub-angle rotation operations N is infinite, x N And y N Equal to cos (theta) and sin (theta), respectively, to achieve phase/amplitude conversion. According to equation (2), the maximum value of the sum of the sub-rotation angles can be expressed as:
to cover the range Φ of CORDIC algorithm angle calculation by ± 180 °, a sub-angle rotation operation of j =0 can be added twice. The modified CORDIC algorithm phase/amplitude conversion operation can be described as:
due to the addition of two sub-angle rotation operations of j =0, N being the total number of iteration operations, the correction factor K is modified as:
thus, x in the formula (6) j 、y j And z j As input variable for the sub-angle rotation operation, x j+1 、y j+1 And z j+1 The formula (6) is realized in a field programmable gate array chip through addition/subtraction and shift operation; x is the number of 0 ＝K，y 0 ＝0，z 0 The input of (a) is the angle value at which the trigonometric value is to be calculated; the order of the iteration of the series of sub-angle rotation operations is j =0,1,2,3.
Assuming that the total number of iterations is N, the error of the CORDIC algorithm-based phase/amplitude conversion module described by equation (6) can be expressed as:
as can be seen from the formula (8), the precision of the algorithm is determined by the iteration times and the number of bits of the data register in the operation, so that the precision of the algorithm can be adjusted on line, and high precision can be achieved.
As shown in fig. 4, the circuit of the signal sampling channel is: the positive input terminal of the first operational amplifier 1 is used as the signal input terminal, the negative input terminal of the first operational amplifier 1 is connected with the output terminal of the first operational amplifier 1, the output terminal of the first operational amplifier 1 is connected with the first capacitor C 1 One end of the two ends are connected; a first capacitor C 1 The other end of (1) and a first resistor R 1 A second resistor R 2 Is connected to a first resistor R 1 The other end of (a) is grounded; the positive input terminal of the second operational amplifier and the second resistor R 2 Is connected with the other end of the first operational amplifier, and the negative input end of the second operational amplifier is connected with a third resistor R 3 A fourth resistor R 4 Is connected to the output terminal of the second operational amplifier and the fourth resistor R 4 Another terminal of (1), a second capacitor C 2 Is connected to one end of a third resistor R 3 The other end of the first and second electrodes is grounded; a second capacitor C 2 The other end of (1) and a fifth resistor R 5 One terminal of (C), a third capacitor C 3 Is connected to a third capacitor C 3 And the other end of the resistor and a sixth resistor R 6 Is connected with the positive input end of the third operational amplifier, a sixth resistor R 6 The other end of the first and second electrodes is grounded; negative input end of third operational amplifier and seventh resistor R 7 One end of (1), an eighth resistor R 8 Is connected to the output of the third operational amplifier, and the output of the third operational amplifier is connected to the firstFive resistors R 5 The other end of (1), an eighth resistor R 8 The other end of (1), a ninth resistor R 9 Is connected to one end of a seventh resistor R 7 The other end of the first and second electrodes is grounded; ninth resistor R 9 The other end of (1) and a tenth resistor R 10 One end of (C), a fourth capacitor C 4 One end of the two ends are connected; positive input terminal of the fourth operational amplifier and the tenth resistor R 10 The other end of the first capacitor C 5 Is connected to the negative input terminal of the fourth operational amplifier, and the eleventh resistor R 11 One end of (1), a twelfth resistor R 12 Is connected to the output of the fourth operational amplifier and the fourth capacitor C 4 Another terminal of (1), a twelfth resistor R 12 Is connected to the other end of the resistor, an eleventh resistor R 11 The other end of the first capacitor C 5 And the other end of the same is grounded.
The signal sampling channel is formed by connecting a photoelectric detector with a voltage follower, an RC high-pass filter, an amplifier, a band-pass filter and an analog-digital converter. And the signal sampling channel is used for filtering and pre-amplifying the output signal of the photoelectric detector. Because the detected signal is weak and the noise is relatively large, the preamplifier of the signal channel is required to have low noise, high gain and large dynamic range, and simultaneously, the requirement of matching with the output impedance of the photoelectric detector and having a high common mode rejection ratio is met, so that the optimal noise rejection performance is achieved.
Fig. 4 is a block diagram of a signal sampling channel. A band pass filter (BFP) is a combination of a Low Pass Filter (LPF) and a High Pass Filter (HPF) and selects a frequency of a demodulated signal. The LPF and the HPF both adopt active second-order structures, and the photoelectric detector is connected with a follower for impedance matching. The follower is composed of a first operational amplifier; a first capacitor C 1 And a first resistance R 1 Forming a DC blocking circuit; the amplifying circuit is composed of a second operational amplifier and a second resistor R 2 A third resistor R 3 A fourth resistor R 4 Forming; the high-pass filter is composed of a third operational amplifier and a second capacitor C 2 A third capacitor C 3 A fifth resistor R 5 A sixth resistor R 6 A seventh resistor R 7 An eighth resistor R 8 Composition is carried out; the low-pass filter is composed of a fourth operational amplifier and a fourth capacitor C 4 A fifth capacitor C 5 A ninth resistor R 9 A tenth resistor R 10 Eleventh resistor R 11 And a twelfth resistor R 12 And (4) forming.
The control signal channel for tuning the output optical frequency of the laser is formed by connecting a digital-to-analog converter, a feedback circuit and the laser.
Fig. 5 is a circuit block diagram of the feedback circuit 2: thirteenth resistor R 13 With one end as input, a thirteenth resistor R 13 The other end of which is connected with a sixth capacitor C 6 One end of (1), a fourteenth resistance R 14 One end of the connecting rod is connected; positive input terminal of fifth operational amplifier and fourteenth resistor R 14 The other end of (C), a seventh capacitor C 7 Is connected to the negative input terminal of the fifth operational amplifier and the fifteenth resistor R 15 One end of (1), a sixteenth resistor R 16 Is connected to the output terminal of the fifth operational amplifier and the sixth capacitor C 6 The other end of (1), a sixteenth resistor R 16 Another terminal of (1), a seventeenth resistor R 17 Is connected to a fifteenth resistor R 15 The other end of (C), a seventh capacitor C 7 The other end of the first and second electrodes is grounded; positive input terminal of sixth operational amplifier and eighteenth resistor R 18 Is connected to the negative input terminal of the sixth operational amplifier, and a seventeenth resistor R 17 Another terminal of (1), a nineteenth resistor R 19 Is connected to the output terminal of the sixth operational amplifier and a nineteenth resistor R 19 Another terminal of (1), a twenty-second twelve-resistance R 22 Is connected to an eighteenth resistor R 18 The other end of the first and second electrodes is grounded; positive input terminal of seventh operational amplifier and twenty-first resistor R 21 Is connected to the negative input terminal of the seventh operational amplifier, and a twelfth resistor R 22 The other end of (1), a twenty-third resistor R 23 One end of (1), a twenty-fifth resistor R 25 Is connected with the output end of the seventh operational amplifier and the twenty-fifth resistor R 25 Is connected to the other end of the resistor R, a twenty-first resistor R 21 The other end of the first and second electrodes is grounded; a twenty-third resistor R 23 The other end of the resistor and a twentieth resistor R 20 One end of (1), a twenty-fourth resistor R 24 Is connected to a twentieth resistor R 20 Is connected to a power supply, a twenty-fourth resistor R 24 And the other end of the same is grounded.
The feedback circuit consists of a low-pass filter, an inverting amplifier and an inverting adder. Since the laser frequency tuning terminal cannot apply a negative voltage, an adder is required as a level shift circuit. The low-pass filter is composed of the fifth oneOperational amplifier and thirteenth resistor R 13 A fourteenth resistor R 14 A fifteenth resistor R 15 Sixteenth resistor R 16 A sixth capacitor C 6 A seventh capacitor C 7 Composition is carried out; the inverting amplifier consists of a sixth operational amplifier and a seventeenth resistor R 17 Eighteenth resistor R 18 Nineteenth resistor R 19 Composition is carried out; twentieth resistor R 20 And a twenty-fourth resistor R 24 Providing a dc translation level; the inverting adder is composed of a seventh operational amplifier and a twenty-first resistor R 21 A twenty-second resistor R 22 Twenty third resistor R 23 Twenty-fifth resistor R 25 And (4) forming.
And outputting a signal demodulation value calculated by the FPGA through a digital/analog converter and a low-pass filter, wherein the signal is a gyro rotation signal.
Fig. 6 is a circuit block diagram of the gyro signal output channel 13: twenty-sixth resistor R 26 Has one end as input end, a twenty-sixth resistor R 26 The other end of the capacitor and an eighth capacitor C 8 One end of (1), a twenty-seventh resistor R 27 One end of the two ends are connected; positive input end of eighth operational amplifier and twenty-seventh resistor R 27 The other end of the capacitor C 9 Is connected to the negative input terminal of the eighth operational amplifier and a twenty-eighth resistor R 28 One end of (1), a twenty-ninth resistor R 29 Is connected to the output terminal of the eighth operational amplifier and the eighth capacitor C 8 Another terminal of (1), a twenty-ninth resistor R 29 Is connected to the other end of the ninth capacitor C 9 The other end of (2), a twenty-eighth resistor R 28 And the other end of the same is grounded.
The low-pass filter adopts an active second-order low-pass filter and consists of an eighth operational amplifier and a twenty-sixth resistor R 26 Twenty-seventh resistor R 27 Twenty eighth resistor R 28 Twenty ninth resistor R 29 An eighth capacitor C 8 A ninth capacitor C 9 And (4) forming.
Claims (7)
1. A resonance type optical fiber gyro signal detection method based on coordinate rotation digital computer algorithm is characterized by comprising a modulation signal generation method and a modulation signal demodulation method, wherein the two parts are as follows:
the generation method of the modulation signal comprises the following steps: under the control of a clock, a frequency control register in the field programmable gate array chip controls the frequency of the generated sine wave; the frequency control register is used as the input of a phase accumulator, the phase value output by the phase accumulator is used as the input phase quantity z of a phase/amplitude conversion module 0 ， z 0 Is the phase quantity for which the trigonometric value needs to be calculated; input initial vector coordinate value x of phase/amplitude conversion module 0 Set to a certain value, y 0 Set to 0, output x of the phase/amplitude conversion module N And y N Giving the input phase quantities z, respectively 0 The sine and cosine function values are used for generating sine wave voltage signals as modulation signals through a digital-to-analog converter;
the demodulation method of the modulation signal comprises the following steps: under the control of a clock, a phase control register in the field programmable gate array chip controls the phase difference between the modulation signal and the demodulated signal; phase control register and phase accumulator in modulation signal generation methodTwo input signals are output as an adder, and the phase value output by the adder is used as the input phase quantity z of a phase/amplitude conversion module 0 ，z 0 Is the phase quantity for which the trigonometric value needs to be calculated; sampling a signal containing a frequency component of a modulated signal by an analog/digital converter, wherein the sampled value is used as an input initial vector coordinate value x of a phase/amplitude conversion module 0 ，y 0 Set to 0; output x of phase/amplitude conversion module N The sine wave synchronous amplitude demodulation signal value is given through a low-pass filter, and the voltage demodulation signal is given through a digital/analog converter.
2. The signal detection method of the resonant fiber optic gyroscope based on the cordic algorithm of the cordic claim 1 is characterized in that the phase/amplitude conversion module is: the process of phase/amplitude conversion is achieved by a series of iterations of sub-angle rotation operations; the input parameter of the phase/amplitude conversion module is the phase quantity z 0 Initial vector coordinate value x 0 And y 0 (ii) a Will y 0 Set to 0, when the iteration number N of the sub-angle rotation operation tends to infinity, the output x of the phase/amplitude conversion module N And y N Respectively tend to x 0 ·sin(z 0 ) And x 0 ·cos(z 0 )，z N Tending towards 0.
3. The signal detection method of the resonant fiber optic gyroscope based on the cordic algorithm of the cordic claim 2, characterized in that the iteration of the series of sub-angle rotation operations is: the sub-angle rotation operation may be represented as
Wherein x is j 、y j And z j As input variable for the sub-angle rotation operation, x j+1 、y j+1 And z j+1 The relational expression is the output variable of the sub-angle rotation operation and is realized by adding/subtracting and shifting in a field programmable gate array chip;n is the total number of iterative operations, y 0 ＝0，z 0 Is the angle value for which the trigonometric value is to be calculated; when z is j > 0 or z j When < 0, delta j Respectively taking +1 and-1; the order of the iteration of the series of sub-angle rotation operations is j =0,1,2,3.
4. A signal detection device of a resonant fiber-optic gyroscope based on a coordinate rotation digital computer algorithm is characterized in that: the laser 1 is connected with a first coupler 3, a first phase modulator 4, a first optical fiber circulator 16, a second coupler 20, a second optical fiber circulator 19, a second phase modulator 7 and the first coupler 3; the first phase modulator 4 is connected with a first digital/analog converter 5; the second phase modulator 7 is connected with the second digital/analog converter 6; the first optical fiber circulator 16 is connected with the first photoelectric detector 17, the first signal sampling channel 14 and the first analog/digital converter 11; the second optical fiber circulator 19 is connected with the second photoelectric detector 18, the second signal sampling channel 15 and the second analog/digital converter 12; the second coupler 20 is connected with the fiber resonance ring 21; the third D/A converter 8 is connected with the feedback circuit 2 and the laser 1; the fourth digital/analog converter 10 is connected with a gyro signal output channel 13; the field programmable gate array chip 9 is connected to the first digital-to-analog converter 5, the second digital-to-analog converter 6, the third digital-to-analog converter 8, the fourth digital-to-analog converter 10, the first analog-to-digital converter 11, and the second analog-to-digital converter 12, respectively.
5. A coordinate-based rotation number as claimed in claim 4The resonance type optical fiber gyro signal detection device of the computer algorithm is characterized in that the circuit of the signal sampling channel is as follows: the positive input terminal of the first operational amplifier 1 is used as the signal input terminal, the negative input terminal of the first operational amplifier 1 is connected with the output terminal of the first operational amplifier 1, the output terminal of the first operational amplifier 1 is connected with the first capacitor C 1 One end of the connecting rod is connected; a first capacitor C 1 The other end of (1) and a first resistor R 1 A second resistor R 2 Is connected to one end of a first resistor R 1 The other end of the first and second electrodes is grounded; the positive input terminal of the second operational amplifier and the second resistor R 2 Is connected to the other end of the first operational amplifier, and the negative input terminal of the second operational amplifier is connected to the third resistor R 3 A fourth resistor R 4 Is connected to the output terminal of the second operational amplifier and a fourth resistor R 4 Another terminal of (1), a second capacitor C 2 Is connected to one end of a third resistor R 3 The other end of the first and second electrodes is grounded; second capacitor C 2 The other end of (1) and a fifth resistor R 5 One terminal of (C), a third capacitor C 3 Is connected to a third capacitor C 3 And the other end of the resistor and a sixth resistor R 6 Of the third operational amplifierPositive input ends connected, a sixth resistor R 6 The other end of the first and second electrodes is grounded; negative input end of third operational amplifier and seventh resistor R 7 One end of (1), an eighth resistor R 8 Is connected to the output terminal of the third operational amplifier and the fifth resistor R 5 The other end of (1), an eighth resistor R 8 The other end of (1), a ninth resistor R 9 Is connected to one end of a seventh resistor R 7 The other end of the first and second electrodes is grounded; ninth resistor R 9 The other end of (1) and a tenth resistor R 10 One terminal of (1), a fourth capacitor C 4 One end of the two ends are connected; positive input terminal of the fourth operational amplifier and the tenth resistor R 10 The other end of (C), a fifth capacitor C 5 Is connected to the negative input terminal of the fourth operational amplifier, and the eleventh resistor R 11 One end of (1), a twelfth resistor R 12 Is connected to the output of the fourth operational amplifier, and the output of the fourth operational amplifier is connected to the fourth capacitor C 4 Another terminal of (1), a twelfth resistor R 12 Is connected to the other end of the resistor, an eleventh resistor R 11 The other end of (C), a fifth capacitor C 5 The other end of which is grounded.
6. The apparatus according to claim 4, wherein the feedback circuit 2 comprises: thirteenth resistor R 13 With one end of the resistor R as an input terminal, a thirteenth resistor R 13 And the other end of the first capacitor C and a sixth capacitor C 6 One end of (1), a fourteenth resistance R 14 One end of the two ends are connected; positive input terminal of fifth operational amplifier and fourteenth resistor R 14 The other end of (C), a seventh capacitor C 7 Is connected to the negative input terminal of the fifth operational amplifier, and a fifteenth resistor R 15 One terminal of (1), a sixteenth resistor R 16 Is connected to the output terminal of the fifth operational amplifier and the sixth capacitor C 6 Another terminal of (1), a sixteenth resistor R 16 Another terminal of (1), a seventeenth resistor R 17 Is connected to a fifteenth resistor R 15 The other end of (C), a seventh capacitor C 7 The other end of the first and second electrodes is grounded; positive input terminal of sixth operational amplifier and eighteenth resistor R 18 Is connected to the negative input terminal of the sixth operational amplifier, and a seventeenth resistor R 17 Another terminal of (1), a nineteenth resistor R 19 Is connected to the output terminal of the sixth operational amplifier and a nineteenth resistor R 19 The other end of the first resistor R and a twenty-second resistor R 22 Is connected to an eighteenth resistor R 18 The other end of the first and second electrodes is grounded; positive input terminal of seventh operational amplifier and twenty-first resistor R 21 Is connected with the negative input end of the seventh operational amplifier and the twenty-second resistor R 22 The other end of (1), a twenty-third resistor R 23 One end of (1), a twenty-fifth resistor R 25 Is connected with the output end of the seventh operational amplifier and a twenty-fifth resistor R 25 Is connected to the other end of the resistor R, a twenty-first resistor R 21 The other end of the first and second electrodes is grounded;a twenty-third resistor R 23 And the other end of the resistor and a twentieth resistor R 20 One end of (1), a twenty-fourth resistor R 24 Is connected to a twentieth resistor R 20 The other end of the resistor is connected with a power supply, and a twenty-fourth resistor R 24 And the other end of the same is grounded.
7. The apparatus for detecting signal of resonant fiber optic gyro based on cordic of claim 4 wherein the gyro signal output channel 13 has the following circuit: twenty-sixth resistor R 26 Has one end as input end, a twenty-sixth resistor R 26 The other end of the capacitor and an eighth capacitor C 8 One end of (1), a twenty-seventh resistor R 27 One end of the two ends are connected; positive input end of eighth operational amplifier and twenty-seventh resistor R 27 The other end of (C), a ninth capacitor C 9 Is connected to the negative input terminal of the eighth operational amplifier and a twenty-eighth resistor R 28 One end of (1), a twenty-ninth resistor R 29 Is connected to the output terminal of the eighth operational amplifier and the eighth capacitor C 8 Another terminal of (1), a twenty-ninth resistor R 29 Is connected to the other end of the ninth capacitor C 9 The other end of the resistor R, a twenty-eighth resistor R 28 And the other end of the same is grounded.
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