RU2719210C1 - Echo sounder - Google Patents

Abstract

FIELD: hydro acoustics.

SUBSTANCE: echo sounder relates to hydroacoustic systems for determining depth and can be used for automatic detection of bottom echoes and switching of depth measurement scale depending on current measured depth. Solution of the task is achieved by introducing the possibility of automatic establishment of optimum parameters of the probing pulse and frequency band in the sounder receiver based on analysis of the current depth measured by the echo sounder.

EFFECT: object of the invention is to increase the reliability of the measured depths and to automatically maximize the signal / noise ratio in the sounder receiver in a wide range of measured depths using the echo sounder.

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Description

The present invention relates to the field of sonar, in particular, sonar systems for determining the depth of the water.

It is known that in echo sounders the duration of the probe pulse is related to the signal-to-noise ratio, resolution in depth and the minimum possible depth measured by the echo sounder. To maximize the signal-to-noise ratio, the probing pulse duration τ _imp. , which allows to reduce the passband of the receiving path Δ однако, however, this decreases the resolution in depth and increases the so-called "dead zone" - the minimum measured depth, therefore, if the sonar uses probe pulses of different lengths, the passband of the receiving path of the sounder should be variable and consistent with the duration of the probe pulses and determined according to the expression (A.A. Khrebrov, Ship echo sounders, L, Shipbuilding, 1982, p. 79, formula 2.54.)

To reduce the minimum measured depth with an echo sounder, the duration of the probe pulse should be as small as possible, and it is determined by the passband of the antenna and the echo sounder receiver. The optimal duration of the probe pulse τ _imp.opt , which is consistent with the width of the main maximum of the lobe of the directivity of the echo sounder antenna θ, or the energetically optimal duration, allows you to get the echo signal reflected in the opposite direction simultaneously from the entire voiced area and realize the maximum resolution in depth, determined according to the expression (A.V. Bogorodsky, D. B. Ostrovsky, Hydroacoustic navigation and search and survey means. St. Petersburg, ed. St. Petersburg State Electrotechnical University LETI, 2009, p. 112, 113.).

where H is the current depth measured by the echo sounder, s is the speed of sound, therefore, for the current depth H, the passband Δƒ _opt. the receiving path of the echo sounder is determined by the optimal duration of the probe pulse τ _imp.opt as follows:

When performing surveying of the bottom of the water area with hydroacoustic means, an important task is the correct setting of the range of measured ranges to the bottom (range scale) from the existing set, which is assigned to the operator. Each range scale is characterized by a maximum value of the measured range H _i .

A known echo sounder (Echo sounder. Patent No. 2390796 RU dated 04/27/2009, G01S 15/00), which includes an electronic computer, an information display device (display), an electro-acoustic transducer, a transmitter with step-wise power adjustment, a receiver, an analog-to-digital converter, as well as a serial interface, a device for matching the receiver and transmitter of signals, including a receive-transmit switch. The receiver gain control input provides the resulting gain control function as a product of the step function and the function that compensates for signal attenuation over distance. The transmitter inputs provide control of the radiated power, as well as input of the type and duration of the emitted signal by the operator from the control panel. The disadvantage of this echo sounder is the inability to automatically establish the optimal duration of the probe pulse and the period of its emission depending on the current depth measured by the echo sounder and the low reliability of the measured depths due to the absence of a change in the receiver bandwidth depending on the current depth.

A device for capturing the topography of the bottom of the water area (US Patent No. 4873676, IPC G01S 15/08, 1989), comprising an electro-acoustic transducer, transmitter, receiver with automatic gain control, a control unit, a unit for collecting and processing bottom topography information, a display for display information received. The range scale in this device is changed by comparing the depth value measured in the current sensing cycle with threshold 1 and threshold 2. Thresholds 1 and 2 are set for each range scale before shooting and are stored in the device’s memory for shooting the bottom relief of the water area. If the measured depth value in the current sensing cycle is less than threshold 1, then in the next sensing cycle a range scale is set with a lower maximum value of the measured range. If the measured depth value in the current sensing cycle is greater than threshold 2, then in the next sensing cycle, a range scale with a large maximum value of the measured range is set. If the measured depth value in the current sensing cycle is in the range between threshold 1 and threshold 2, then the range scale is not changed to the next sounding cycle.

The disadvantage of this device is the constant duration of the probe pulse and the passband of the receiver for all scales and, as a result, the low reliability of the measured depths on large depth measurement scales, as well as the lack of the ability to automatically establish the optimal bandwidth for the receiver and the parameters of the probe pulse, depending on the current depth measured echo sounder. There is also a significant drawback of the device, namely, that the scale is changed by the operator from the control panel, whose reaction has a relatively low speed and is not always adequate, especially in the area with a very dissected bottom.

The closest set of features to the proposed echo sounder is an echo sounder (Echo sounder. Patent No. 2241242 RU dated 03/31/2004, G01S 15/00), including a microcontroller, transmitter, receiver, analog-to-digital converter, as well as an electro-acoustic transducer, a display, a time unit automatic gain control. The transmitter is made with step-wise power adjustment, the adjustment input of which is connected to the microcontroller, the receiver is made with two gain control inputs, the first adjustment input, which provides step-by-step gain control, is connected to the microcontroller, and the second adjustment input is connected to the output of the temporary automatic gain control unit.

The disadvantage of this echo sounder is the constant duration of the probe pulse and the passband of the receiver for all scales and, as a result, the low reliability of the measured depths on large depth measurement scales due to the too wide passband of the receiver, as well as the inability to automatically establish the optimal parameters of the probe pulse and passband receiver, depending on the current depth, measured by an echo sounder, which does not allow to maximize the signal-to-noise ratio in minik echo sounder in the entire range of measured depths. In addition, the echo sounder has a significant disadvantage in that the change of scale is assigned to the operator, who has a relatively low speed and cannot always make the right decisions (for example, in the case of a complex bottom topography), which can lead to false information about the topography bottom. Often the operator sets the range scale not optimally, with a large margin for the maximum value of the measured range (scale), as a result, the depth estimation algorithms are negatively affected due to the need to filter the echo signals of double (multiple) reflection from the bottom.

The objective of the invention is to increase the reliability of the measured depths and automatic maximization of the signal / noise ratio in the sonar receiver in a wide range of measured depths.

The technical result of the invention is to establish the optimal parameters of the probe pulse and the passband of the receiver based on the analysis of the current measurement depth.

To ensure the specified technical result, an echo sounder containing a microcontroller and a transmitter in series with a step-wise power adjustment, the adjustment input of which is connected to the microcontroller, an analog-to-digital converter, the output of which is connected to the microcontroller, and an electro-acoustic transducer connected to the transmitter, a temporary automatic adjustment unit amplification and a display, the input of which is connected to the microcontroller, also containing a receiver made with two inputs and gain control, the first gain control input providing step-by-step gain control is connected to the microcontroller, and the second gain control input is connected to the output of the temporary automatic gain control unit, the output of the receiver is connected to the input of the analog-to-digital converter, and its input is connected to the output of the electro-acoustic converter and the output of the transmitter, new features are introduced, namely, the receiver is equipped with an input for selecting the bandwidth, an analysis unit for the current depth is entered into the sounder, which is connected to the microcontroller and the unit for generating the duration of the probe signal and the radiation period with one input and three outputs, the input of which is connected to the output of the current depth analysis unit, the first output is connected to the second input of the transmitter, the second output is connected to the input of the receiver bandwidth selection, and its third the output is connected to the input of the automatic time gain control unit.

The introduction of new blocks, that is, a block for analyzing the current depth and a block for generating the duration of the probe pulse and the period of radiation and communications, will automatically establish the optimal parameters of the probe pulse and the passband of the receiver, depending on the current depth measured by the echo sounder.

The essence of the invention is presented in FIG. 1, where:

1 microcontroller (MK)

2 transmitter

3 receiver

4 analog-to-digital converter (ADC)

5 electro-acoustic transducer (EAP)

6 display

7 block temporary automatic gain control (VARU)

8 block forming the duration of the probe pulse and the radiation period (BFZI)

9 current depth analysis block (BATG)

For practical implementation of the echo sounder, the FASTWEL CPC 800 microcontroller can be used as a microcontroller - a single-board EPIC computer of industrial design on the Intel Pentium M 2 GHz processor with a set of interfaces and an integrated electronic Flash disk for storing the echo sounder software.

As a transmitter, a pulse amplifier assembled according to a bridge circuit can be used, and by changing the supply voltage of the bridge output stage, the emitted transmitter power can be changed from 1 W to 300 W in steps of 6 dB; by changing the supply voltage of the output stage must control MK 4-bit parallel code.

As a receiver, an amplifier based on the AD600 IC can be used - an amplifier with a variable voltage gain in the range from 0 to 80 dB, which should be provided by the VARU unit, and AD7945 IC - a digital-to-analog converter that can stepwise change the receiver gain from 0 up to 48 dB after 3 dB. under the influence of an 8-bit code coming from MK.

As a band-pass filter in the receiver, it is possible to use an IC of a 4-pole active filter MAX275, with a programmable bandwidth and Q factor, or perform it in a standard way on standard IC operational amplifiers, but this will require a larger number of them.

For example, an LCD monitor with a VGA interface can be used as a display.

As an ADC, the AD7892-2 IC can be used - a 12-bit ADC with a parallel interface and a speed of 1.6 μs.

VARU can be implemented based on the IC of a binary n-bit counter, ROM, in which the law of VARU is recorded; the ROM outputs must be connected to a digital-to-analog converter, for example AD7845, which generates a variable-voltage VARU from 0 to 2.5 V, which controls the receiver gain - AD600.

The BATG block can be implemented on the basis of the IMS 1903BE91T single-chip 16-bit microcomputer with ADC, Flash memory, an array of timers, a set of serial interfaces and input / output ports.

The BFZI block can be implemented on the basis of IC of programmable binary counters, for example, a timer 80С54, which includes 3 programmable independent counters, one can be used to form the period of radiation of the probe pulse, the second to form the duration of the probe pulse, and the third to form the frequency the radiation of the probe pulse and the IC of the decoder, for example 1554ID7, to select the passband of the receiver, or else it is possible to implement the functions of the BFZI block on an array of programmable dependent timers and parallel port, which are part of the IMS 1903BE91T, on which the BATG block is made.

During operation, the echo sounder should provide high reliability of measurements in a wide range of measured depths, which requires it to maximize the signal-to-noise ratio in the receiver in this range of measured depths.

The proposed echo sounder works as follows.

Usually, when developing an echo sounder, it is necessary to measure the maximum depth H, but it is necessary to provide the smallest possible minimum measured depth with an echo sounder.

We determine the optimal parameters of the echo sounder, namely, the duration of the probe pulse τ _imp. , the passband of the receiving path Δƒ (receiver), as a function of the sub-ranges of depth measurement with an echo sounder. We divide the maximum required depth of measurement with an echo sounder N into k subbands (scales) Hi according to formula 1.

where, i is the scale number, i = 1: k, with k corresponding to the minimum depth measurement scale H _k , and 1 (unit) the maximum depth H ₁ = H.

The smallest scale is determined depending on the operational requirements for the echo sounder and the bandwidth of its EAP and the duration of its transient process after the radiation of the probe pulse, which determine the minimum possible duration of the probe pulse and the passband of the receiver should ensure its transmission with minimal distortion, and which usually It is several meters, sometimes 10-20 meters. Each scale H _i corresponds to its own period of radiation of the probe pulse T _i which is calculated according to formula 2, and T _i is formed by the BFZI block based on the analysis of the current depth H _tech. in the BATG block.

where c is the speed of sound in water, usually c = 1500 m / s.

Each scale H _i corresponds to its own optimal duration of the probe pulse τ _{imp. I} , which is calculated according to formula 3, while θ is the width of the directivity characteristic of the EAP at a level of 0.7 from the maximum, and τ _imp.i is formed by the BFZI block based on the analysis of the current depth H _tech. in the BATG block.

The probe pulse formed by the BFZI block with τ _imp.i , T _i and the filling frequency at the working frequency of the EAA is fed to the transmitter input through its first output.

Each probe pulse duration τ _imp.i corresponds to the receiver bandwidth Δƒ _i , which is calculated by formula 4, and Δƒ _{i is} installed in the receiver by the BFZI unit through its second output based on the analysis of the current depth H _tech. in the BATG block.

The BATG block analyzes in the current radiation cycle the reception of the current value of the measured depth H _tech. by comparing with two depth thresholds on the current scale H _i - with the upper threshold value H _lower. = 0.4 * H _i and with a lower threshold value H up _. = 0.8 * H _i and on the basis of this comparison and according to the rules laid down in its work, issues a command to the BFZI block to select the receiver bandwidth Δƒ and the scale, that is, to generate a probe pulse with parameters corresponding to the current value of the measured depth H _tech. - with a radiation period T _i and a duration τ _imp.i according to those calculated according to formulas 2 and 3, the reception for the next radiation cycle. Note that the upper threshold value H is up _. on the current scale, H _i coincides with the lower threshold value H _lower. on a larger scale - H _i-1 and lower threshold value H _lower. on the current scale, H _i coincides with the upper threshold value H up _. on a smaller scale H _{i + 1} , which allows in the case of a graphical representation of the profile of measured depths on the display in coordinates the distance traveled - depth always display this profile in the middle part of the display vertically, which is convenient for the operator to observe the depth profile.

The BFZI block generates, at its first output, which is connected to the transmitter input, a probe pulse of duration τ _imp.i with a period T _i and a frequency filling determined by the working frequency of the EAP. Also, the BFZI block at its second output, which is connected to the input of the receiver bandwidth selection, generates a receiver bandwidth selection command Δƒ _i . Also, the BFZI block at its third output forms an envelope of the probe pulse of duration τ _imp.i with a period T _i , without frequency filling, to ensure synchronization of the operation of the transmitter and the VARU block.

When the echo sounder is turned on, in the first cycle the radiation is received, that is, at the time the software starts up, the MP sets the minimum gain in the receiver through the first input of the step adjustment of gain, the minimum radiation power in the transmitter through the BATG block and BFZI unit sets the maximum passband Δƒ _k . The BATG block gives a command to enter the BFZI block to generate a probe pulse with a frequency filling and with a minimum radiation period T _k and a minimum duration τ _imp.k , which correspond to the smallest scale H _k that is supplied to the transmitter input, and then it is fed to the EA which emits it into the water in the direction of the bottom, at the same time the BFZI block through its third output gives out the envelope of the probe pulse (ZI) to the VARU, which always starts the VARU when the ZI emits and synchronizes the operation of the VARU with the transmitter and receiver. Next, the reflected echo from the bottom is received by the EAP, amplified by the receiver, filtered and where its dynamic range is compressed under the influence of the ARG, and from the output of the receiver it goes to the ADC, where its envelope is converted to digital form. From the ADC output, the echo envelope enters the MC, where it is processed according to the algorithm described in patent 2241242 RU dated 03/31/2004, G01S 15/00, and the current depth H _{tech is} calculated _. , the value of which is displayed for the operator on the display and transmitted to the input of the BATG block. The BATG block compares the value of the current depth H _tech. with a lower threshold value of depth H _lower. and the upper threshold value of depth H up _. , for the current scale H _k . Next, the BATG block analyzes the comparison of the current depth with threshold values:

- if the current depth is H _tech. less than the lower threshold H _lower. = 0.4 * H _k , then in the next cycle the radiation reception does not change the scale for measuring the depth and passband Δƒ _k ,

- if the current depth is H _tech. less than the upper threshold H up _. = 0.8 * H _k , then in the next cycle the radiation reception does not change the scale for measuring the depth and passband Δƒ _k ,

- if the current depth is H _tech. more than the upper threshold H up _. = 0.8 * H _k , the BATG block gives a command to the BFZI to switch the radiation to the next scale H _k-1 in the next cycle, i.e., BFZI in the next cycle the radiation will form the probe pulse duration τ _imp.k-1 with a period of T _{to -1} and set the passband Δƒ _k-1 ,

- if in any cycle the radiation is received on the Hi scale, the current depth is H _tech. less than the lower threshold H _lower. = 0.4 * H _i , then in the next radiation cycle, the depth measurement scale changes to the previous, smaller scale H _{i + 1} and the passband Δƒ _{i + 1 is set} ,

- if in any cycle the radiation is received on the Hi scale, the current depth is H _tech. is greater than the upper threshold H _top = 0.8 * H _i , then in the next cycle the radiation receives a change in the depth measurement scale to the next large scale H _i-1 and the passband Δƒ _{i-1 is set} ,

- if in any cycle the radiation reception on the Hi scale, the current depth value is simultaneously less than the upper depth threshold H _top = 0.8 * H _i , and more than the lower depth threshold H _lower. = 0.4 * H _i , then for the next radiation cycle, reception of a change in the depth measurement scale does not occur and the bandwidth remains the same Δƒ _i ,

- if in any cycle the radiation reception on the Hi scale for some reason does not turn out to be measured, then the BATG block instructs the BFZI to switch the radiation to the next large scale H _i-1 in the next cycle and the bandwidth Δƒ _{i is set -1} , and so on,

- if in any cycle the radiation reception on the H ₁ scale, the greatest for the echo sounder, for some reason the depth is not measured, then the BATG unit issues a command to the BFZI to switch the radiation to the lowest scale H _k in the next cycle and the bandwidth Δƒ is set _k , and then with each radiation emission cycle, the scales automatically change in the direction of increase with the formation, for each of them, of the optimal duration of the probe pulse and its radiation period and the corresponding receiver bandwidth is set, d as long as an echo signal from the bottom is detected on any scale and the depth is measured.

In the process of operation of the echo sounder, in addition to setting the optimal parameters of the ZI and the passband of the receiver, MP, according to the results of processing the echo signal in the current cycle, the radiation receives, sets the gain in the receiver and the radiated power in the transmitter for the next radiation cycle, reception calculated based on the analysis of the echo signal parameters according to the algorithm described in patent No. 2241242 RU dated 03/31/2004, G01S 15/00.

Thus, based on the analysis of the measured depth value in the current radiation cycle, the BATG unit of the echo sounder, the reception in the next radiation cycle, the device automatically selects from the existing set of scales and receiver bandwidths the optimal depth measurement scale and the passband of the receiver and issues a command to the BFZI to form the corresponding probe pulse with optimal parameters, which maximizes the signal-to-noise ratio on all depth measurement scales and increases the reliability of the measured depths. Thus, the objective of the invention is solved.

The automatic setting of optimal parameters of ZI and receiver bandwidth provides an extension of the range of measured depths with an echo sounder and optimal resolution of the echo sounder at all depths (scales), thereby ensuring the achievement of a technical result. The automatic setting of the optimal period of emission of the probe pulse, depending on the current depth of measurement, makes it possible to perform measurements in water at high speeds of the sonar carrier, which minimizes material and time costs for work and eliminates errors associated with the actions of the sonar operator.

The proposed echo sounder is fully automatic and does not require operator intervention. The advantage of the described echo sounder is the automatic search for an echo of the signal from the bottom, setting the optimal scale for measuring depth and ZI parameters, an expanded range of measured depths, and high reliability of the measured depths.

Claims (1)

An echo sounder containing a microcontroller and a transmitter with step-wise power control in series, the adjustment input of which is connected to the microcontroller, an analog-to-digital converter, the output of which is connected to the microcontroller, as well as an electro-acoustic transducer connected to the transmitter, a temporary automatic gain control unit and a display whose input connected to a microcontroller, also comprising a receiver configured with two gain control inputs, a first force control input A step-wise gain control is connected to the microcontroller, and the second gain control input is connected to the output of the temporary automatic gain control unit, the output of the receiver is connected to the input of the analog-to-digital converter, and its input is connected to the output of the electro-acoustic converter and the transmitter output, characterized in that the receiver is equipped with an input for selecting a bandwidth, a unit for analyzing the current depth, the input of which is connected to the microcontroller, and a unit for generating of the probe signal and the radiation period with one input and three outputs, the input of which is connected to the output of the current depth analysis unit, the first output is connected to the second input of the transmitter, the second output is connected to the input of the receiver bandwidth selection, and its third output is connected to the input of the automatic unit gain time adjustment.

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