CN113534163A - High-precision Doppler log system - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
- G01S15/50—Systems of measurement, based on relative movement of the target
- G01S15/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01S15/582—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of interrupted pulse-modulated waves and based upon the Doppler effect resulting from movement of targets
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/539—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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Abstract
The invention discloses a high-precision Doppler log system which comprises a power supply board for supplying power to the whole system, a receiving and transmitting combined transducer array which consists of piezoelectric ceramic elements and is used for converting sound energy into electric signals, a power amplification board for amplifying transmitted pulse signals, a signal processing board for algorithm processing, outputting height and speed information, a signal conditioning board for amplifying, filtering and analog-to-digital converting echo signals, a non-acoustic sensor board for measuring and transmitting data such as attitude, temperature and salt depth and the like, and a display and control module for sending control commands and displaying system information. The high-precision Doppler log system transmits a single-frequency pulse signal or an m-sequence pseudo-random coding broadband signal according to a control signal of the display control module, receives an echo signal, performs algorithm processing on the echo signal, and sends information such as speed, height to bottom and the like to the display control module for displaying, so that the height measurement error is less than 1%, and the speed measurement error is less than 0.3%.
Description
Technical Field
The invention relates to the field of Doppler log systems, in particular to a high-precision Doppler log system.
Technical Field
Under the condition that the underwater working environment is limited, the miniaturized Doppler log with high speed measurement precision is widely applied to unmanned underwater vehicles. With the rapid development of unmanned underwater vehicle technology and the continuous expansion of application scenes, the requirement on the accuracy of underwater navigation is increasingly improved, and the speed measurement accuracy of the DVL is a decisive factor of the navigation performance. Therefore, a high-precision Doppler log system is developed and used for providing accurate speed information for ocean equipment such as an underwater vehicle and the like. The device has important significance and effect in military and civil aspects and provides equipment guarantee for ocean development tools.
Disclosure of Invention
The invention aims to provide a high-precision Doppler log system for providing accurate speed information for marine equipment such as an underwater vehicle.
The invention provides a high-precision Doppler log system which mainly comprises a receiving and transmitting cooperation transducer array, a power amplifier board, a signal processing board, a signal conditioning board, a non-acoustic sensor board, a power board and a display control module.
The receiving and transmitting cooperative transducer array consists of four independent transducers, the four transducers are arranged into a Janus array structure, and the axis of the radiation surface of each transducer forms an included angle of 25 +/-0.1 degrees with the central axis of the transducer array; the four transducers simultaneously convert pulse signals transmitted by the power amplification board into sound wave signals, then receive underwater echo signals, convert the underwater echo signals into electric signals and send the electric signals to the signal conditioning board.
The power amplifier board is composed of an array signal driving circuit, a half-bridge power amplifier and a filtering output module. The digital signal driving circuit adopts an INFINENON IR2010STRPBF MOS driving chip, receives two paths of complementary PWM signals S + and S-input chip high-low side driving MOS tubes, drives no output when the SD control signal is high level, and the low level is effective; the half-bridge power amplification circuit adopts an INFINENON IRFI4020H-117P field effect transistor, an upper bridge and a lower bridge are formed by two MOS transistors, the upper bridge arm is connected with a power amplifier power supply, the lower bridge arm is grounded, the dead time is controlled to be 332ns, two paths of complementary PWM signals control the G pole of the MOS transistor, and the upper bridge arm and the lower bridge arm are respectively conducted to realize the power amplification effect; the filtering output circuit is formed by LC low-pass filtering, and the inductor is 10uH and is made of full red-2 materials. The power loss is effectively reduced, and the capacitance is selected to be 4.7 nf. The resonance frequency is 734.127Khz, so that high-frequency components can be effectively filtered out, and signals can be restored and output.
The signal processing board consists of three parts, namely an FPGA, a DSP and an MCU. The low-power consumption MCU adopts an STM32L476 chip, and mainly has the functions of realizing external command interaction and power supply management of a signal processing board; the FPGA adopts EP4CE40 produced by Altera corporation, the main functions are signal acquisition and preprocessing, a gain control signal is output to a signal conditioning board and 4 paths of power amplifier driving signals are output through an isolation interface, wherein an isolator selects ISO7760 and is a 6-channel high-speed isolation chip, and an isolation power supply is provided by a power amplifier side; the DSP adopts an OMAP-L138 chip and contains an ARM9 and a C6748 core, and the main functions of the DSP are to receive echo data preprocessed by the FPGA end through a uPP interface, perform bottom distance measurement, velocity measurement or troposphere velocity measurement algorithm processing on the echo data, and send a processing result to the MCU to be transmitted to the display control module.
The transmitted signal is divided into narrowband and wideband signals. Narrowband signal: signal frequency of f0The pulse width is 5 grades such as 1ms, 2ms, 5ms, 10ms, 20ms and the like under the condition of 600 KHz; broadband signal: adopting m sequence code, the code element number is 7; filling 10 single-frequency pulse signals in a single code element, wherein the frequency of the signals is 600 KHz; the repetition times of the m-sequence coding are respectively 5 grades such as 8, 17, 42, 85, 170 and the like, and the pulse type corresponds to 5 grades such as 1ms, 2ms, 5ms, 10ms, 20ms and the like of the narrow-band signal. The signal processing algorithm flow is as follows:
array element accumulation:
echo signals are collected, and effective processing can be carried out on the data only by accumulating certain sampling data, wherein the accumulation length is NT 266240. Let x1(266240, 0:3) is the accumulated echo sample data, the first dimension representing sample points and the second dimension representing array element numbers.
Quadrature demodulation:
the orthogonal demodulation is to change the real signal received by the array element into a complex signal, and the traditional orthogonal demodulation method is adopted, and the specific steps are as follows:
(1) time domain multiplication
And performing time domain processing on the array element data to obtain I, Q two paths of signals.
I(n,m)＝x1(n,m)·cos(2πf0n/NT) (1)
Q(n,m)＝x1(n,m)·sin(2πf0n/NT) (2)
Wherein m is 0,1,2,3, n is 1,2.
(2) Low pass filtering
Low-pass filtering I, Q signals to obtain filtered signal I1(n.m) and Q1(n.m)：
Where b, a are coefficients of the 4 th order low pass filter 100e 3. n is 0,1, …, NT, fsIs the signal sampling rate. The quadrature demodulation part is already completed in the FPGA, and the accumulated length of array element data at the DSP end is 26624 x 2 because of two parts of a real part and an imaginary part.
Radial distance to bottom: the radial bottom-to-bottom distance is used for determining the height of the sea bottom by performing energy integration processing on the echo signals.
1. Calculating the sound velocity:
the sound velocity calculation adopts an empirical formula given by Leroy and is determined by temperature, salinity and water depth:
wherein c is the speed of sound (m/s); t ═ temperature (° c); salinity (parts per thousand: ppt); h is depth (m).
2. And (3) calculating the height of the sea bottom by an energy integration method:
converting the filtered signal and the resamples into a complex signal sig:
sig(1:dd:NT,m)＝I1(1:dd:NT,m)+Q1(1:dd:NT,m) (5)
in the equation, dd is a down-sampling multiple and is currently set to 10.
(1) Integrating the complex signal energy yields:
sig2(1:dd:NT,m)＝I1 2(1:dd:NT,m)+Q1 2(1:dd:NT,m) (6)
(2) energy average Power _ mean is calculated:
Power_mean＝mean(sig2(1:dd:NT,m))*2 (7)
(3) and searching the bottom echo time:
when sig2(n2, m) > Power _ mean and sig2(n2+ 1: n2+10, m) > Power _ mean, then the sampling point nh at the bottom echo time is equal to n 2.
(4) Radial bottoming distance HoutAnd (3) calculating:
3. and (3) bottom velocity measurement calculation:
(1) taking coherent pulse pair y1And y2：
y1(:,m)＝sig(NH(m)+1:NH(m)+Nw-1,m) (10)
y2(:,m)＝sig(NH(m)+tn+1:NH(m)+tn+Nw-1,m) (11)
Where tn is the delay time taken for τ · fs, τ is the delay time between pulse pairs; nw represents the length of the coherent pulse pair, and proposes a pulse width length for a single-frequency signal and an integral multiple of the period length for an M-sequence code; nh (m) measured for each beam.
(2) Complex autocorrelation algorithm:
where ". sup." denotes taking conjugation.
(3) Calculating the phase:
wherein imag () and real () represent imaginary and real part operations.
(4) Calculating the Doppler frequency shift:
from the above formula, it can be seen that there is a measurement range (-1/2 τ,1/2 τ) for measuring doppler shift by using the phase-resolving algorithm, which obviously cannot satisfy the velocity measurement range, so that the ambiguous phase needs to be calculated, and different ambiguity-resolving algorithms are adopted for the single-frequency signal and the M-sequence signal.
4. Single frequency signal doppler ambiguity resolution:
by measuring the difference between the line spectrum frequency of the echo signal and the ideal line spectrum frequency, the doppler shift can also be obtained, the algorithm is greatly affected by the frequency resolution, but the accurate doppler shift can be calculated by combining the doppler of the two algorithms, and the specific process is as follows:
(1) echo signal line spectrum detection
Nf(m)＝i,if abs(x4(i,m))＝＝max(abs(x4(:,m))) (15)
In the formula, x4(: m) is a spectrum signal of the complex signal sig, and nf (m) i is a sampling point corresponding to the highest point of the spectrum.
(2) Calculating a fuzzy phase
Wherein f isd1(m) is the frequency offset found by fft, and n (m) is the number of ambiguity periods.
(3) Calculating Doppler frequency offset
(4) Calculating radial velocity
5. M-sequence signal doppler ambiguity resolution:
the spectrum of the M sequence is composed of a plurality of line spectra, so that the M sequence cannot be processed by a single-frequency signal doppler ambiguity resolution algorithm, wherein the doppler ambiguity resolution algorithm is implemented by measuring the shift of the autocorrelation side peak of the M sequence, and the specific process is as follows:
(1) calculating an autocorrelation function
The essence of solving the autocorrelation function in the time domain is a convolution process, and the calculation amount is large, so the autocorrelation function is calculated by adopting a frequency domain calculation method, and the specific process is as follows:
y4(:,m)＝xcorr(sig(:,m)) (20)
y4is the autocorrelation function of the complex signal.
(2) Side peak detection
Wherein n is 0,1,2,35Is the average of the autocorrelation function. The specific detection mode is as follows:
the resulting nside (m) is the sample point of the interval between the detected side peak and the main peak.
(3) Calculating a fuzzy phase
In the formula, TPIs the period of the encoded signal.
(4) Calculating Doppler frequency offset
(5) Calculating radial velocity
The signal conditioning board is composed of a filter circuit, an amplifying circuit and an analog-to-digital conversion circuit. The filter circuit is realized by an active filter formed by operational amplifiers, and the pass band range of the filter is designed to be 500 kHz-900 kHz; the amplifying circuit selects a variable gain amplifier AD8338, the gain control mode is voltage control, and a signal processing board can provide control voltage to realize the TVG (time-varying gain) function; the analog-to-digital conversion adopts a 14-bit multichannel synchronous sampling ADC chip LTC2170-14, and the ADC acquires echo signals and then sends the data to a signal processing board for processing.
The non-acoustic sensor board mainly provides installation positions for an attitude sensor and a temperature and salinity sensor in a DVL (Doppler log) and provides a serial interface for a signal processing board.
The power panel mainly supplies power to the signal processing board, the signal conditioning board, the power amplification board and the non-acoustic sensor board.
The power amplifier board supplies power and selects two LM5022 boost chips of TI company, has a wide voltage input range of 6V-60V, and the power switch frequency is set to 240Khz, so that the influence of multiple harmonic frequency on 600K signals is prevented. The voltage 95V is used for an input power supply of a power amplifier MOS tube, one path of power amplifier output is 25W, 4 paths of power amplifier output are 100W, one LM5022 circuit is designed to output 0.6A, the total power is 57W, the requirement that 2 paths of power amplifier output are 25W is met, and two LM5022 circuits meet the requirement that 4 paths of power amplifier output; an LM43602 chip of TI company is selected, is a synchronous step-down DC converter, has wide voltage input of 3.5V-36V (maximum 42V), outputs 4 paths of power amplification required current 0.0035A and provides the power amplification chip for power supply, and meets the design requirement; a TLV70450DBVR LDO chip of TI company is selected, the input voltage range is 2.5V-24V, the output current is 150mA, VCC 15V is converted into 5V voltage to be supplied to a driving chip and a signal processing board isolation chip.
The signal conditioning board and the signal processing board need 2 power supplies, the chip works with +5V positive power supply and-5V negative power supply. The positive power supply 5V adopts a VRB2405YMD-6WR3 isolation voltage stabilization DCDC chip of MONSUN company, wide voltage input of 18V-36V (maximum to 40V) is realized, isolation voltage stabilization single-path output is realized, the efficiency can reach 88%, the no-load power consumption is 0.12W isolation voltage 1500VDC, and meanwhile, input under-voltage protection and output short-circuit, overcurrent and overvoltage protection are realized, so that the design requirement is met; the negative power supply adopts an LM2662 switch capacitor voltage converter of TI company, can convert a 5V power supply into-5V power supply output, can support 200mA output to the maximum extent, and meets the design requirement.
The positive working power supply 5V of the attitude sensor and the temperature, salinity and depth sensor chip in the non-acoustic sensor board is supplied with power by the VRB2405YMD-6WR3 isolation and voltage regulation DCDC chip.
The display control module has the main functions that a worker selects a working mode at the upper computer end, sends a working instruction to the signal processing board through the serial port RS232, receives a processing result of the signal processing board in real time and displays the processing result.
The invention has the beneficial effects that:
the invention designs and realizes a high-precision Doppler log system, and multiple times of experiments prove that the speed measurement error of the Doppler log system is less than 0.3 percent, the distance measurement error is 1 percent, and the high-precision Doppler log system can provide accurate speed and bottoming height information for ocean equipment such as an underwater vehicle and the like.
Drawings
The invention is further illustrated with reference to the following figures and examples.
FIG. 1 is a block diagram of the system architecture of the present invention.
Fig. 2 shows the arrangement of the transmitting/receiving combined/power-displacing devices in the present invention.
Fig. 3 is a general block diagram of the power amplifier circuit of the present invention.
Fig. 4 is a block diagram of the signal processing board of the present invention.
Fig. 5 is a block diagram of the signal conditioning board assembly of the present invention.
FIG. 6 is a block diagram of the non-acoustic sensor panel of the present invention.
Fig. 7 is a general block diagram of the power strip circuit of the present invention.
FIG. 8 is a block diagram of the display control circuit of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, the high-precision doppler log system of the present invention comprises a transceiver transducer array, a power amplifier board, a signal processing board, a signal conditioning board, a non-acoustic sensor board, a power board, and a display control module. The system is powered on, and the power panel supplies power to other modules of the system; the staff sends the control instruction to the signal processing module through the RS232 through the display control module; the signal processing board is provided with an algorithm module and transmits two paths of complementary PWM signals to the power amplification board; the power amplifier board amplifies, filters and outputs and drives the receiving and transmitting combined transducer array; the receiving and transmitting combined transducer array transmits narrowband or broadband sound wave signals, receives echo signals and sends the echo signals to the signal conditioning plate; the signal conditioning board filters, amplifies and carries on the analog-to-digital conversion echo signal, send the data gathered to the signal processing board; the signal processing board receives data such as the attitude, the temperature, the salinity and the like transmitted by the non-acoustic sensor board, performs signal processing algorithm operation on the acquired echo data, and sends the processed result to the display control model through the RS232 serial port for display.
The specific signal processing algorithm flow of the internal part of the signal processing board is as follows:
array element accumulation:
echo signals are collected, and effective processing can be carried out on the data only by accumulating certain sampling data, wherein the accumulation length is NT 266240. Let x1(266240, 0:3) is the accumulated echo sample data, the first dimension representing sample points and the second dimension representing array element numbers.
Quadrature demodulation:
the orthogonal demodulation is to change the real signal received by the array element into a complex signal, and the traditional orthogonal demodulation method is adopted, and the specific steps are as follows:
(1) time domain multiplication
And performing time domain processing on the array element data to obtain I, Q two paths of signals.
I(n,m)＝x1(n,m)·cos(2πf0n/NT) (1)
Q(n,m)＝x1(n,m)·sin(2πf0n/NT) (2)
Wherein m is 0,1,2,3, n is 1,2.
(2) Low pass filtering
Low-pass filtering I, Q signals to obtain filtered signal I1(n.m) and Q1(n.m)：
Where b, a are coefficients of the 4 th order low pass filter 100e 3. n is 0,1, …, NT, fsIs the signal sampling rate. The quadrature demodulation part is already completed in the FPGA, and the accumulated length of array element data at the DSP end is 26624 x 2 because of two parts of a real part and an imaginary part.
Radial distance to bottom: the radial bottom-to-bottom distance is used for determining the height of the sea bottom by performing energy integration processing on the echo signals.
1. Calculating the sound velocity:
the sound velocity calculation adopts an empirical formula given by Leroy and is determined by temperature, salinity and water depth:
wherein c is the speed of sound (m/s); t ═ temperature (° c); salinity (parts per thousand: ppt); h is depth (m).
2. And (3) calculating the height of the sea bottom by an energy integration method:
converting the filtered signal and the resamples into a complex signal sig:
sig(1:dd:NT,m)＝I1(1:dd:NT,m)+Q1(1:dd:NT,m) (5)
in the equation, dd is a down-sampling multiple and is currently set to 10.
(1) Integrating the complex signal energy yields:
sig2(1:dd:NT,m)＝I1 2(1:dd:NT,m)+Q1 2(1:dd:NT,m) (6)
(2) energy average Power _ mean is calculated:
Power_mean＝mean(sig2(1:dd:NT,m))*2 (7)
(3) and searching the bottom echo time:
when sig2(n2, m) > Power _ mean and sig2(n2+ 1: n2+10, m) > Power _ mean, then the sampling point nh at the bottom echo time is equal to n 2.
(4) Radial bottoming distance HoutAnd (3) calculating:
3. and (3) bottom velocity measurement calculation:
(5) taking coherent pulse pair y1And y2：
y1(:,m)＝sig(NH(m)+1:NH(m)+Nw-1,m) (10)
y2(:,m)＝sig(NH(m)+tn+1:NH(m)+tn+Nw-1,m) (11)
Where tn is the delay time taken for τ · fs, τ is the delay time between pulse pairs; nw represents the length of the coherent pulse pair, and proposes a pulse width length for a single-frequency signal and an integral multiple of the period length for an M-sequence code; nh (m) measured for each beam.
(6) Complex autocorrelation algorithm:
where ". sup." denotes taking conjugation.
(7) Calculating the phase:
wherein imag () and real () represent imaginary and real part operations.
(8) Calculating the Doppler frequency shift:
from the above formula, it can be seen that there is a measurement range (-1/2 τ,1/2 τ) for measuring doppler shift by using the phase-resolving algorithm, which obviously cannot satisfy the velocity measurement range, so that the ambiguous phase needs to be calculated, and different ambiguity-resolving algorithms are adopted for the single-frequency signal and the M-sequence signal.
4. Single frequency signal doppler ambiguity resolution:
by measuring the difference between the line spectrum frequency of the echo signal and the ideal line spectrum frequency, the doppler shift can also be obtained, the algorithm is greatly affected by the frequency resolution, but the accurate doppler shift can be calculated by combining the doppler of the two algorithms, and the specific process is as follows:
(5) echo signal line spectrum detection
Nf(m)＝i,if abs(x4(i,m))＝＝max(abs(x4(:,m))) (15)
In the formula, x4(: m) is a spectrum signal of the complex signal sig, and nf (m) i is a sampling point corresponding to the highest point of the spectrum.
(6) Calculating a fuzzy phase
Wherein f isd1(m) is the frequency offset found by fft, and n (m) is the number of ambiguity periods.
(7) Calculating Doppler frequency offset
(8) Calculating radial velocity
5. M-sequence signal doppler ambiguity resolution:
the spectrum of the M sequence is composed of a plurality of line spectra, so that the M sequence cannot be processed by a single-frequency signal doppler ambiguity resolution algorithm, wherein the doppler ambiguity resolution algorithm is implemented by measuring the shift of the autocorrelation side peak of the M sequence, and the specific process is as follows:
(1) calculating an autocorrelation function
The essence of solving the autocorrelation function in the time domain is a convolution process, and the calculation amount is large, so the autocorrelation function is calculated by adopting a frequency domain calculation method, and the specific process is as follows:
y4(:,m)＝xcorr(sig(:,m)) (20)
y4is the autocorrelation function of the complex signal.
(3) Side peak detection
Wherein n is 0,1,2,35Is the average of the autocorrelation function. The specific detection mode is as follows:
the resulting nside (m) is the sample point of the interval between the detected side peak and the main peak.
(3) Calculating a fuzzy phase
In the formula, TPIs the period of the encoded signal.
(4) Calculating Doppler frequency offset
(5) Calculating radial velocity
As shown in fig. 2, the transceiver transducer array is composed of four independent transducers, the four transducers are arranged in a Janus array structure, and the axis of the radiation surface of each transducer forms an included angle of 25 ° ± 0.1 ° with the central axis of the transducer array; the four transducers simultaneously convert pulse signals transmitted by the power amplification board into sound wave signals, then receive underwater echo signals, convert the underwater echo signals into electric signals and send the electric signals to the signal conditioning board.
As shown in fig. 3, the power amplifier board is composed of three modules, namely, an array signal driving circuit, a half-bridge power amplifier, and a filter output module. The digital signal driving circuit adopts an INFINENON IR2010STRPBF MOS driving chip, receives two paths of complementary PWM signals S + and S-input chip high-low side driving MOS tubes, drives no output when the SD control signal is high level, and the low level is effective; the half-bridge power amplification circuit adopts an INFINENON IRFI4020H-117P field effect transistor, an upper bridge and a lower bridge are formed by two MOS transistors, the upper bridge arm is connected with a power amplifier power supply, the lower bridge arm is grounded, the dead time is controlled to be 332ns, two paths of complementary PWM signals control the G pole of the MOS transistor, and the upper bridge arm and the lower bridge arm are respectively conducted to realize the power amplification effect; the filtering output circuit is formed by LC low-pass filtering, and the inductor is 10uH and is made of full red-2 materials. The power loss is effectively reduced, and the capacitance is selected to be 4.7 nf. The resonance frequency is 734.127Khz, so that high-frequency components can be effectively filtered out, and signals can be restored and output.
As shown in FIG. 4, the signal processing board is composed of three parts, namely an FPGA, a DSP and an MCU. The low-power consumption MCU adopts an STM32L476 chip, and mainly has the functions of realizing external command interaction and power supply management of a signal processing board; the FPGA adopts EP4CE40 produced by Altera corporation, the main functions are signal acquisition and preprocessing, a gain control signal is output to a signal conditioning board and 4 paths of power amplifier driving signals are output through an isolation interface, wherein an isolator selects ISO7760 and is a 6-channel high-speed isolation chip, and an isolation power supply is provided by the power amplifier board; the DSP adopts an OMAP-L138 chip and is internally provided with an ARM9 core and a C6748 core, and the main functions of the DSP are to receive echo data preprocessed by the FPGA end through a uPP interface, process the echo data by a signal processing algorithm, send a processing result to the MCU and transmit the processing result to the display control module.
As shown in fig. 5, the signal conditioning board is composed of a filter circuit, an amplifier circuit, and an analog-to-digital converter. The filter circuit is realized by an active filter formed by operational amplifiers, and the pass band range of the filter is designed to be 500 kHz-900 kHz; the amplifying circuit selects a variable gain amplifier AD8338, the gain control mode is voltage control, and a signal processing board can provide control voltage to realize the TVG (time-varying gain) function; the analog-to-digital conversion adopts a 14-bit multichannel synchronous sampling ADC chip LTC2170-14, and the ADC acquires echo signals and then sends the data to a signal processing board for processing.
As shown in fig. 6, the non-acoustic sensor board mainly provides mounting positions for the attitude sensor and the temperature and salt depth sensor in the DVL (doppler log) and provides a serial interface to the signal processing board.
As shown in fig. 7, the power board mainly supplies power to the signal processing board, the signal conditioning board, the power amplification board, and the non-acoustic sensor board.
The power amplifier board supplies power and selects two LM5022 boost chips of TI company, has a wide voltage input range of 6V-60V, and the power switch frequency is set to 240Khz, so that the influence of multiple harmonic frequency on 600K signals is prevented. The voltage 95V is used for an input power supply of a power amplifier MOS tube, one path of power amplifier output is 25W, 4 paths of power amplifier output are 100W, one LM5022 circuit is designed to output 0.6A, the total power is 57W, the requirement that 2 paths of power amplifier output are 25W is met, and two LM5022 circuits meet the requirement that 4 paths of power amplifier output; an LM43602 chip of TI company is selected, is a synchronous step-down DC converter, has wide voltage input of 3.5V-36V (maximum 42V), outputs 4 paths of power amplification required current 0.0035A and provides the power amplification chip for power supply, and meets the design requirement; a TLV70450DBVR LDO chip of TI company is selected, the input voltage range is 2.5V-24V, the output current is 150mA, VCC 15V is converted into 5V voltage to be supplied to a driving chip and a signal processing board isolation chip.
The signal conditioning board and the signal processing board need 2 power supplies, the chip works with +5V positive power supply and-5V negative power supply. The positive power supply 5V adopts a VRB2405YMD-6WR3 isolation voltage stabilization DCDC chip of MONSUN company, wide voltage input of 18V-36V (maximum to 40V) is realized, isolation voltage stabilization single-path output is realized, the efficiency can reach 88%, the no-load power consumption is 0.12W isolation voltage 1500VDC, and meanwhile, input under-voltage protection and output short-circuit, overcurrent and overvoltage protection are realized, so that the design requirement is met; the negative power supply adopts an LM2662 switch capacitor voltage converter of TI company, can convert a 5V power supply into-5V power supply output, can support 200mA output to the maximum extent, and meets the design requirement.
The positive working power supply 5V of the attitude sensor and the temperature, salinity and depth sensor chip in the non-acoustic sensor board is supplied with power by the VRB2405YMD-6WR3 isolation and voltage regulation DCDC chip.
As shown in fig. 8, the display control module mainly functions that a worker selects a working mode at the upper computer end, sends a working instruction to the signal processing board through the serial port RS232, and receives and displays a processing result of the signal processing board in real time.
The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.
Claims (4)
1. A high accuracy Doppler log system characterized in that: the device consists of a receiving and transmitting combined transducer array, a power amplifier board, a signal processing board, a signal conditioning board, a non-acoustic sensor board, a power panel and a display control module; the system is powered on, and the power panel supplies power to other modules of the system; the control instruction is sent to the signal processing module through the RS232 through the display control module; the signal processing board is provided with an algorithm module and transmits two paths of complementary PWM signals to the power amplification board; the power amplifier board amplifies, filters and outputs and drives the receiving and transmitting combined transducer array; the receiving and transmitting combined transducer array transmits a narrow-band or wide-band signal, receives an echo signal and transmits the echo signal to the signal conditioning board; the signal conditioning board filters, amplifies and carries on the analog-to-digital conversion echo signal, send the data gathered to the signal processing board; the signal processing board receives the attitude and thermohaline depth data transmitted by the non-acoustic sensor board, performs signal processing algorithm operation on the acquired echo data, and sends the processed result to the display control model through the RS232 serial port for display.
2. A high accuracy doppler log system as in claim 1 wherein: the receiving and transmitting combined transducer array consists of four independent transducers, the four transducers are arranged into a Janus array structure, and the axis of the radiation surface of each transducer forms an included angle of 25 +/-0.1 degrees with the central axis of the transducer array; the four transducers simultaneously convert pulse signals transmitted by the power amplification board into sound wave signals, then receive underwater echo signals, convert the underwater echo signals into electric signals and send the electric signals to the signal conditioning board.
3. A high accuracy doppler log system as in claim 1 wherein: the power amplifier board consists of a digital signal driving circuit, a half-bridge power amplifier and a filtering output module; the digital signal driving circuit adopts an INFINENON IR2010STRPBF MOS driving chip, receives two paths of complementary PWM signals S + and S-, and inputs the high-side and low-side driving MOS tubes of the chip, and the SD control signal is driven to have no output when being at a high level and is effective at a low level; the half-bridge power amplifying circuit adopts an INFINENON IRFI4020H-117P field effect transistor, an upper bridge and a lower bridge are formed by two MOS transistors, the upper bridge arm is connected with a power amplifier power supply, the lower bridge arm is grounded, two paths of complementary PWM signals control the G pole of the MOS transistor, and the upper bridge arm and the lower bridge arm are respectively conducted to realize the power amplifying effect; the filtering output circuit is formed by LC low-pass filtering.
4. A high accuracy doppler log system as in claim 1 wherein: the signal processing board consists of three parts, namely an FPGA, a DSP and an MCU; the MCU realizes external command interaction and power supply management of the signal processing board; the FPGA realizes signal acquisition and preprocessing, outputs a gain control signal to a signal conditioning board and outputs 4 paths of power amplifier driving signals through an isolation interface, wherein an isolator is a 6-channel high-speed isolation chip, and an isolation power supply is provided by a power amplifier side; the DSP receives the echo data preprocessed by the FPGA end through the uPP interface, carries out bottom distance measurement, velocity measurement or troposphere velocity measurement processing on the echo data, and sends a processing result to the MCU to transmit the processing result to the display control module.
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