A bottom-tracking signal receiving circuit and bottom-tracking signal processing method based on a 600kHz mobile ADCP

Abstract

This invention discloses a bottom-tracking signal receiving circuit and a bottom-tracking signal processing method based on a 600kHz mobile ADCP, comprising a power supply module, a transceiver converter, a bottom-tracking signal receiving circuit, and a bottom-tracking signal conditioning module. The power supply module provides the operating voltage to the bottom-tracking signal receiving circuit, and the transceiver converter, bottom-tracking signal receiving circuit, signal conditioning module, and signal processing board are electrically connected in sequence. This invention effectively achieves the reception of 600kHz mobile ADCP bottom-tracking signals, and through the energy centroid method combining matched filtering, band limiting, and threshold weighting, it realizes the functions of receiving, processing, and calculating parameters of bottom-tracking signals while ensuring a certain signal-to-noise ratio, improving the accuracy of bottom-tracking detection depth and bottom-tracking speed, and providing strong support for the accuracy of river detection information.

Description

Technical Field

[0001] This invention relates to the receiving technology of underwater acoustic echo signal systems, and particularly to a 600kHz mobile ADCP signal bottom tracking signal receiving circuit and bottom tracking signal processing method, belonging to the field of underwater acoustic signal detection. Background Technology

[0002] Water flow velocity and flow rate information are crucial references for hydrological environmental analysis and watershed flood forecasting. Therefore, the measurement of water flow velocity and flow rate has always been an important aspect of hydrological observation. Traditional methods for measuring water flow velocity and flow rate mainly include manual boat measurement, cableway measurement, and bridge measurement. These methods require significant manpower and resources, and the results are not ideal, lacking in real-time performance and accuracy.

[0003] In summary, given the shortcomings of the aforementioned measurement methods, current water velocity and flow rate measurements must possess characteristics such as high precision, real-time performance, and environmental adaptability. To meet these requirements, acoustic Doppler current profilers have emerged. The main principle of ADCP (Advanced Doppler Current Profiler) for measuring water velocity and flow rate is to utilize the abundant microorganisms and suspended matter in the water as a medium for sound wave reflection. When the water body and the measuring instrument are in relative motion, the sound waves reflected by the suspended matter in the water will generate a Doppler frequency shift due to the Doppler effect. This Doppler frequency shift reflects the relative velocity between the bottom, the water body, and the measuring instrument. Once the receiving device receives the echo of the sound wave, it can process it to obtain the Doppler frequency component, thereby calculating the velocity of the water body and the bottom relative to the measuring instrument, and finally, the flow velocity information. However, to achieve high-precision and high-reliability flow velocity profile measurement, the bottom tracking signal receiving circuit and the bottom tracking signal processing method are among the core bottlenecks of the entire system.

[0004] Currently, the receiving circuit uses primary and secondary bandpass filters. However, in-band fluctuations occur, leading to suboptimal results. In signal receiving circuits, bandpass filters can filter out noise interference outside the frequency band. With a 100kHz bandwidth and a center frequency of 600kHz, a steep transition band is required in the design of bandpass filters to minimize the impact of out-of-band noise on the received signal. The steep transition band and in-band flatness of the bandpass filter in ADCP receiving circuits are contradictory, making it difficult to achieve optimal performance. Furthermore, excessive primary amplification and time gain control result in excessive amplification. In existing receiving circuits, signal amplification can only be achieved through primary amplification and time gain control. Under the same time gain control, the primary amplification becomes excessive, leading to increased noise in the signal receiving channel and thus increasing the self-noise of the receiving circuit. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a bottom tracking signal receiving circuit and bottom tracking signal processing method based on a 600kHz mobile ADCP, which effectively realizes the reception and processing of bottom tracking signals.

[0006] The technical solution adopted in this invention is as follows:

[0007] A bottom tracking signal receiving circuit based on a 600kHz mobile ADCP includes a power supply module, a transceiver combiner, a bottom tracking signal receiving circuit, and a bottom tracking signal conditioning module. The power supply module provides the operating voltage for the bottom tracking signal receiving circuit, and the transceiver combiner, the underwater acoustic signal receiving circuit, the signal conditioning module, and the signal processing board are electrically connected in sequence.

[0008] A further description of a 600kHz mobile ADCP bottom tracking signal receiving circuit is characterized in that the bottom tracking signal receiving circuit comprises a first-stage low-noise amplifier, a second-order high-pass filter, a second-stage amplifier, second-order high-pass and second-order low-pass filters, a time gain control, a fourth-order low-pass filter, and a signal conditioning module connected in sequence. The signal conditioning module is connected to the signal processing board, and the first-stage low-noise amplifier is connected to the transceiver converter.

[0009] Furthermore, the power supply module provides a voltage of ±5V.

[0010] Furthermore, the transceiver array described above adopts the Janus array structure.

[0011] Furthermore, the optimal operating frequency for the transceiver converter described above is 600kHz.

[0012] Furthermore, the filter designs described above all adopt the circuit topology of Sallen-Key active filters and utilize the frequency response characteristics of Butterworth filters.

[0013] Another object of the present invention is to provide a method for processing tracking signals based on a 600kHz mobile ADCP, the method comprising the following steps:

[0014] The transceiver receiver receives underwater reflected signals. The bottom tracking signal receiving circuit amplifies, filters, re-amplifies, re-filters, performs automatic gain control, and filters the received signals before inputting them into the signal conditioning module and then into the signal processing board. The signal processing board processes the signals and calculates the signal energy while measuring the water flow velocity. If the energy is greater than the designed threshold, the system determines that the water layer has reached the bottom. Then, the echo of the water layer is processed using a time window. When the peak energy of the window exceeds the background noise threshold of 20 dB and exceeds it for multiple consecutive windows, and the window is a local maximum, it is determined to be the bottom. Matched filtering is used to process the signal, and several points are taken near the output peak to calculate the energy weighting center. Then, the subsampling accuracy of the bottom depth is obtained through calculation. Attached Figure Description

[0015] Figure 1 This is a structural block diagram of the present invention.

[0016] Figure 2 This is a flowchart of the bottom tracking signal processing of the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0018] like Figure 1As shown, an embodiment of the present invention provides a bottom-tracking signal receiving circuit based on a 600kHz mobile ADCP, including a power supply module, a transceiver combiner, a bottom-tracking signal receiving circuit, a signal conditioning module, and a signal processing board. The power supply module provides operating voltage for the 600kHz mobile ADCP bottom-tracking signal receiving circuit and the signal conditioning module. The transceiver combiner, the 600kHz mobile ADCP bottom-tracking signal receiving circuit, the signal conditioning module, and the signal processing board are connected sequentially. The bottom-tracking signal receiving circuit consists of a first-stage low-noise amplifier (OPA847), a second-order high-pass filter, a second-stage amplifier (OPA847), a second-order high-pass plus low-pass filter, a time gain control (AD605), a fourth-order low-pass filter, and a signal conditioning module connected sequentially. The signal conditioning module is connected to the signal processing board. The first-stage low-noise amplifier is connected to the transceiver combiner. The first-stage low-noise amplifier is used to amplify weak underwater echo signals. The amplifier itself has very low noise and adopts a low-noise amplification design to improve the output signal-to-noise ratio. The filter design in the bottom-tracking signal receiving circuit adopts the circuit topology of Sallen-Key active filters and utilizes the frequency response characteristics of Butterworth filters. The power supply module uses two TPS54160 step-down modules to step down the voltage to ±5V to power the signal receiving circuit and signal conditioning module. The transducers used are transceiver-combined transducers, and the array adopts a Janus array structure. The optimal operating frequency for the transceiver-combined transducer is 600kHz. The signal processing module uses FPGA and DSP, but is not limited to these.

[0019] In operation, the power supply module, bottom tracking signal receiving circuit, signal conditioning module, and signal processing board are stacked and sealed within a watertight chamber. The transducer array uses a Janus array configuration and is connected to the bottom tracking signal receiving circuit. The transducer receives reflected signals from the bottom of the water, which are amplified, filtered, and subjected to automatic gain control by the bottom tracking signal receiving circuit before being transmitted to the signal processing board for further signal processing. The signal processing board performs filtering and smoothing, window energy calculation, matched filtering, and echo interception on the signal, measures the required parameters, and then sends the data to the host computer via serial communication.

Claims

1. A tracking signal receiving circuit based on a 600kHz mobile ADCP, characterized in that, It includes a power supply module, a transceiver converter, a bottom tracking signal receiving circuit, a signal conditioning module, and a signal processing board. The power supply module provides the operating voltage for the 600kHz mobile ADCP bottom tracking signal receiving circuit and the signal conditioning module. The transceiver converter, the 600kHz mobile ADCP bottom tracking signal receiving circuit, the signal conditioning module, and the signal processing board are connected in sequence.

2. The 600kHz mobile ADCP bottom tracking signal receiving circuit according to claim 1, characterized in that, The bottom tracking signal receiving circuit consists of a first-stage low-noise amplifier, a second-order high-pass filter, a second-stage amplifier, second-order high-pass and second-order low-pass filters, a time gain control, a fourth-order low-pass filter, and a signal conditioning module connected in sequence. The signal conditioning module is connected to the signal processing board, and the first-stage low-noise amplifier is connected to the transceiver converter.

3. The tracking signal receiving circuit based on a 600kHz mobile ADCP as described in claim 2, characterized in that, The power supply module provides a voltage of ±5V.

4. A tracking signal receiving circuit based on a 600kHz mobile ADCP as described in claim 2, characterized in that, The aforementioned transceiver array adopts the Janus array structure.

5. The tracking signal receiving circuit based on a 600kHz mobile ADCP as described in claim 1, characterized in that, The optimal operating frequency for the transceiver is 600kHz.

6. A method for processing tracking signals based on a 600kHz mobile ADCP, characterized in that, The method includes the following steps: The transceiver receiver receives the reflected echo signal from the bottom of the water. The bottom tracking signal receiving circuit amplifies the received signal sequentially, performs high-pass filtering to remove noise, amplifies again, applies high-pass and low-pass filters to remove noise, performs adjustable gain amplification, low-pass filtering, and signal conditioning before inputting it to the signal processing board. The signal processing board processes the signal and calculates the signal energy while measuring the water flow velocity. If the energy exceeds the designed threshold, the system determines that the water layer has reached the bottom. Then, the echo of the water layer is processed using a time window. When the peak energy of the window exceeds the background noise threshold by 20 dB and continues to exceed it for multiple windows, and the window becomes a local maximum, it is determined to be the bottom. Matched filtering is used to process the signal, and several points near the output peak are selected to calculate the energy weighting center. Then, the sub-sampling precision bottom depth is obtained through calculation.

7. The method for processing tracking signals based on a 600kHz mobile ADCP as described in claim 6, characterized in that, The energy centroid method described above combines band-limiting and threshold weighting. Band-limiting calculates the centroid only within the frequency range related to the expected Doppler shift, avoiding out-of-band noise interference. Threshold weighting only includes spectral lines with power greater than a certain threshold.

8. A tracking signal receiving circuit based on a 600kHz mobile ADCP as described in claim 2, characterized in that, The filter design in the bottom tracking signal receiving circuit adopts the circuit topology of Sallen-Key active filters and uses the frequency response characteristics of Butterworth filters.

9. A tracking signal receiving circuit based on a 600kHz mobile ADCP as described in claim 2, characterized in that, The time gain control mentioned above uses a logarithmic gain variable amplifier to control the gain.

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