RU2545067C1 - Active sonar - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: distance to a given target is determined based on measurement of the response delay time at the output of a second matched filter for a specifically generated (based on echo signal response at the output of a first matched filter) auxiliary composite signal, wherein the duration of the response at the output of the second matched filter is considerably shorter than the duration of the echo signal response at the output of the first matched filter.

EFFECT: high accuracy of determining distance to a target.

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Description

The invention relates to sonar technology, and more particularly to the field of active sonar, including active sonar, designed to detect objects, measure coordinates and motion parameters of detected objects.

Known active sonar (RF patent No. 2346295) containing acoustic emitting and receiving antennas, a device for generating a sounding signal, a generating device, a control device, a device for generating directivity characteristics, a unit for measuring the delay time of an echo signal relative to the moment of emission of a sounding signal, a unit for measuring the angle of arrival echo in the vertical plane, block measuring the depth of the target.

Known active sonar (RF patent No. 2408897), containing a series-connected synchronization device, a device for generating a sounding signal, a generating device and a radiating acoustic antenna, a series-connected receiving acoustic antenna, a device for generating directivity characteristics, a matched filtering device, an echo signal detection device, a device determine the angle of arrival of the echo signal.

However, in these sonars there is no device for determining the distance to the target.

By the number of common features, the closest analogue of the invention is an active sonar containing a serially connected synchronization device, a complex probing signal generating device, a generating device and a radiating acoustic antenna, also containing a receiving acoustic antenna in series, a directivity characteristic forming device, the first matched filter, device echo detection, while the second output of the device is formed a complex sounding signal is connected to the second input of the first matched filter, also containing a device for determining the distance to the target (Mitko V.B., Evtyutov A.P., Gushchin S.E. Hydroacoustic communications and surveillance. L .: Sudostroenie, 1982. S.122-127, 138-142).

The disadvantage of this prototype sonar is that it is not possible to emit a complex signal with the required bandwidth is limited due to insufficient bandwidth of the emitting acoustic antenna. As a result, the necessary accuracy in determining the distance to the target is not achieved. This is due to the fact that when complex signals are used, the error in determining the distance is greater, the longer the response time at the output of the matched filter, and the response time, in turn, increases with decreasing signal bandwidth.

The technical result of the invention is to increase the accuracy of determining the distance to the target.

To achieve this technical result, an active sonar containing a serially connected synchronization device, a device for generating a complex sounding signal, a generator device and a radiating acoustic antenna, also containing a serially connected receiving acoustic antenna, a beamforming device, a first matched filter, an echo detection device wherein the second output of the complex probing signal generating device is connected n with the second input of the first matched filter, also containing a device for determining the distance to the target, new features are introduced, namely: a serially connected storage device, a device for extracting the signal response of a complex echo signal, a modulator and a second matched filter, and a device for generating an auxiliary modulating function is also introduced a complex signal and a strobe generation device, while the input of the auxiliary modulating function modulating function generating device is connected to the output ohms of the signal response complex echo signal extraction device, and the first and second outputs of the auxiliary complex signal modulating function generating device are connected to the second inputs of the modulator and the second matched filter, respectively, the input of the gate generating device is connected to the output of the echo detection device, the output of the first matched filter connected to the first input of the storage device, the first, second and third outputs of the strobe generation device are connected to the second input of the storage device device, the second input device selection signal complex response of the echo signal and the first input device determining the distance to the target, respectively, a second input coupled to an output of the second matched filter, the second input of the echo detection device is connected to the second output of the synchronization device.

The specified technical result is achieved due to the fact that the determination of the distance to the target is based on measuring the response delay time at the output of the second matched filter for a specially formed auxiliary complex signal, and the duration of this response is much less than the response duration at the output of the first matched filter. This is because the auxiliary complex signal is formed with a bandwidth substantially larger than the bandwidth of the complex probing signal. Note that the accuracy of determining the distance to the target depends on the duration of the response by which this distance is determined: in this case, it is the response of a specially formed complex signal at the output of the second matched filter. This result is achieved when the newly introduced blocks, the connections between them and the connections of these blocks with other sonar blocks work together.

The invention is illustrated in figure 1 and figure 2, where figure 1 shows a block diagram of the proposed active sonar, and figure 2 presents the envelope of the response signal at the output of the second matched filter (solid line) and the envelope of the signal response at the output of the first matched filter (dashed line).

The active sonar (Fig. 1) contains a serially connected synchronization device 3, a device 4 for generating a complex sounding signal, a generator device 5 and a radiating acoustic antenna 1. The sonar (Fig. 1) also contains a serially connected receiving acoustic antenna 2, a directivity characteristic device 6 , a first matched filter 7, an echo detection device 8, and a target distance determining device 13. The second output of the device 4 is connected to the second input of the device 7. Also, the active sonar contains a sequentially connected storage device 9, a device 10 for extracting a signal response of a complex echo signal, a modulator 11 and a second matched filter 12. The input of the device 14 for generating the modulating function of the auxiliary complex signal connected to the output of the device 10, and the first and second outputs of the device 14 are connected to the second inputs of the modulator 11 and the second matched filter 12, respectively. The input of the gate generating device 15 is connected to the output of the device 8, the output of the device 7 is connected to the first input of the device 9, the first, second and third outputs of the device 15 are connected to the second input of the device 9, the second input of the device 10 and the first input of the device 13, respectively. The second input of the device 13 is connected to the output of the second matched filter 12, and the second input of the device 8 is connected to the second output of the device 3.

The practical implementation of the blocks included in the invention is known from the practice of hydroacoustics and is implemented through the use of digital devices.

Block 9 and matched filters 12, 13 can be implemented on the basis of technical solutions given in the book Design of pulse and digital devices of radio engineering systems. / Grishin Yu.P., Kazarinov Yu.M., Katikov V.M. and etc.; Ed. Yu.M. Kazarinova. M .: Higher. Shk., 1985. on S.51 and S.147-150.

Blocks 11, 14 are performed using technical solutions given in the book Digital Radio Navigation Devices / V.V. Barashenkov, A.E. Lutchenko, E.M. Skorokhodov et al .; under the editorship of V.B. Smolova. M .: Sov. Radio, 1980. S.196-206.

Blocks 10, 15 are implemented using the technical means described in the book Design of pulse and digital devices of radio systems. / Grishin Yu.P., Kazarinov Yu.M., Katikov V.M. and etc.; Ed. Yu.M. Kazarinova. M .: Higher. school., 1985. S.155-163.

The operation of the device is as follows. The device 4 forming a complex sounding signal generates sounding signals. The sonar emits a probe signal using a generator device 5 and a radiating acoustic antenna 1. The echo signal reflected from the object from the output of the receiving acoustic antenna 2 is fed to the directivity characteristics forming device 6. From the output of device 6, the signal array arrives at device 7, which provides consistent filtering of the received signals, while the reference signal from the output of block 4 is received at the other input of block 7. At the output of block 7, the signal process is transmitted to the echo signal detection device 8 and to the input of the memory device 9, which operates in the update mode of the stored information. When an echo signal is detected, a strobe pulse is generated in the strobe generation device 15, the middle of which corresponds to the moment of detection of the echo signal, and the duration of which makes it possible, taking into account device errors, to generate the necessary signal process array in block 9, including a certain length of time both echo response and noise. This array is transmitted to block 10. In block 10, the signal response of the echo signal is extracted from the array received in block 10. The signal response of the complex echo signal in the form of a radio pulse (i.e., a pulse with a high-frequency filling) from block 10 and the modulating function of the auxiliary complex signal from block 14 are received at the inputs of modulator 11. From the output of block 11, the generated, based on echo response, complex signal. At the other input of block 12, the modulating function of the auxiliary complex signal from block 14 is received. As a result, the output of block 12 gives a compressed response of the generated auxiliary complex signal in the form of an envelope of a radio pulse.

The response time of the auxiliary complex signal is significantly shorter than the signal response of the echo signal. This effect is illustrated by the example with the help of figure 2. Figure 2 presents:

- the envelope of the signal response of the echo signal (dashed line) at the output of the first matched filter, the bandwidth of the complex probe signal generated in this case is 100 Hz, the duration of the main lobe of the envelope of the signal response of the echo signal by level (minus 3 dB) is, respectively, 10 ms

- the envelope of the response of the complex signal at the output of the second matched filter (solid line), the bandwidth of the auxiliary complex signal generated in this case is 400 Hz, the duration of the main lobe of the envelope of the signal response of the auxiliary complex signal in terms of (minus 3 dB) is 2, 5 ms;

Thus, in this example, the duration of the response of the generated auxiliary complex signal is 4 times less than the duration of the response of the echo signal, due to this there is a significant increase in the accuracy of determining the distance to the target.

From the output of block 12, the response envelope of the second matched filter is input to the device 13 for determining the distance to the target. In block 13, the interval τ _{3 is} determined between the time t _{and the} corresponding end of the radiation of the probe signal and the time t _m corresponding to the maximum output response of block 12. Next, in block 13, the distance to the target is determined using the relation:

D = c · τ _3/2,

where c is the speed of sound in water.

The value of τ ₃ is determined in block 13 by the ratio:

τ ₃ = τ _p + τ _m

where τ _str is the time interval between the end of the radiation and the moment the gate starts, measured in block 15;

τ _m - the time interval between the beginning of the gating pulse and the moment t _m , is measured in block 13.

The device 3 controls in time the generation of the probe signal (block 4) and, accordingly, the operation of the generator device 5, and also provides through block 8 synchronization of the operation of blocks 9, 10, 13, 14 and 15.

The use of a storage device, a device for extracting the signal response of a complex echo signal, a device for generating the modulating function of an auxiliary complex signal, a modulator, a second matched filter, a strobe output device, with the corresponding connections between these blocks and the connections of these blocks with other active sonar blocks, improves accuracy determining the distance to the target based on measuring the response delay time at the output of the second matched filter for specially shaped auxiliary complex signal, and the duration of this response is significantly less than the duration of the signal response of the echo signal.

This allows us to assume that the claimed technical result is achieved.

Claims (1)

An active sonar containing a serially connected synchronization device, a device for generating a complex sounding signal, a generator device and a radiating acoustic antenna, also containing a serially connected receiving acoustic antenna, a beamforming device, a first matched filter, an echo detection device, and the second output of the device the formation of a complex sounding signal is connected to the second input of the first matched filter also comprising a device for determining a distance to a target, characterized in that a sequentially connected memory device, a device for extracting a signal response of a complex echo signal, a modulator and a second matched filter are introduced into it, a device for generating an modulating function of an auxiliary complex signal and a strobe generation device are also introduced, wherein the input of the device for generating the modulating function of the auxiliary complex signal is connected to the output of the signal response isolation device with a false echo signal, and the first and second outputs of the auxiliary complex signal modulating function generating device are connected to the second inputs of the modulator and the second matched filter, respectively, the input of the strobe generation device is connected to the output of the echo detection device, the output of the first matched filter is connected to the first input of the storage devices, the first, second and third outputs of the strobe generation device are connected to the second input of the storage device, the second input of the device is highlighted I complex signal response of the echo signal and the first input device determining the distance to the target, respectively, a second input coupled to an output of the second matched filter, the second input of the echo detection device is connected to the second output of the synchronization device.

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