CN113777594B - Nonlinear sonar minimum detectable signal-to-noise ratio test method and system - Google Patents
Nonlinear sonar minimum detectable signal-to-noise ratio test method and system Download PDFInfo
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Abstract
The invention provides a nonlinear sonar minimum detectable signal-to-noise ratio test method and a nonlinear sonar minimum detectable signal-to-noise ratio test system, comprising the following steps: measuring experimental equipment based on the difference frequency signal equivalent sound source level, and actually measuring the difference frequency equivalent sound source level; collecting and recording 0-degree wave beam difference frequency signal time domain waveforms; based on the minimum detectable signal-to-noise ratio test experimental equipment, recording the effective value of the filtered difference frequency signal voltage; calculating propagation loss; the transmitting matrix stops transmitting, the standard signal source outputs a time domain waveform of the difference frequency signal, the time domain waveform is transmitted after passing through the power amplifier and the standard sound source, the transmitting period is T2, a target which is larger than a preset sonar operating distance index and is closest to the preset sonar operating distance index is used as a reference object, the voltage effective value of the difference frequency signal output by the standard signal source is adjusted from large to small, and when the reference object disappears on a sonar image, the voltage effective value of the difference frequency signal output by the standard signal source is recorded; recording the noise spectrum level in the background noise band; a minimum detectable signal to noise ratio is calculated.
Description
Technical Field
The invention relates to the field of nonlinear sonar performance testing methods, in particular to a nonlinear sonar minimum detectable signal-to-noise ratio testing method and system.
Background
The nonlinear sonar (here, the sonar using the parametric emission technology, non-parametric reception) has the characteristics of low-frequency narrow beam and no side lobe, has the characteristics of long acting distance, is suitable for turbid water areas and shallow sea complicated sea areas, and has been effectively applied to the fields of underwater small target detection, seabed shallow stratum detection and underwater self-guiding.
Patent document CN105891805B (application number 201610327756.6) discloses a method for evaluating sonar detection performance under different environmental noise conditions. And testing a standard propagation loss database under a good hydrologic condition low-noise environment constructed by the propagation loss of each frequency and the background along with the distance change of the sea area under the test depth under the good hydrologic environment to obtain the relationship between the propagation loss and the detection distance. If the standard propagation loss database for the sea area is not already established, the database is first established for comparison and table lookup. The invention can solve the problem that the sonar detection performance evaluation is too dependent on the environment noise environment, changes the defect that the sonar detection performance index can be evaluated only in a good hydrologic environment, saves a great amount of time and resources and improves the working efficiency. The sonar detection performance evaluation result has unified evaluation result, and can be compared and analyzed, so that a reliable basis is provided for judging the quality of sonar performance.
In the field of sonar performance testing, in order to reduce the requirements on test sites, environments and equipment and improve test efficiency, the sonar minimum detectable signal-to-noise ratio is generally used to reflect the sonar operating distance. The actual working signal of the conventional system sonar is ideal, the difference between the actual working signal and the standard signal is basically negligible, and the minimum detectable signal-to-noise ratio can be accurately measured by the method of actually measuring the propagation loss and adjusting the standard signal emission size of the standard sound source, so that the satisfaction of the sonar operating distance index is judged, as shown in fig. 1 (the distance D is larger than the far-field distance). However, the nonlinear sonar transmitting system is very complex, and large differences exist between actual working signals and standard signals, and energy loss formed by the differences can cause large errors in the minimum detectable signal-to-noise ratio measuring process, so that the measured value of the minimum detectable signal-to-noise ratio is superior to the sonar actual capability, and the requirement on the sonar working distance is reduced. The energy loss caused by these differences mainly comprises the emission loss E caused by the in-band non-uniformity of the emission system n1 Conversion zone loss E caused by insufficient length of nonlinear effect equivalent end-fire array n2 Conversion rate loss E caused by nonlinear effect different frequency downshifting ratios n3 Also includes some minor other losses E n others 。
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a nonlinear sonar minimum detectable signal-to-noise ratio test method and a nonlinear sonar minimum detectable signal-to-noise ratio test system.
The invention provides a nonlinear sonar minimum detectable signal-to-noise ratio test method, which comprises the following steps:
step (a)S1: based on the difference frequency signal equivalent sound source level measurement experimental equipment, when the nonlinear sonar works normally, the difference frequency equivalent sound source level SL is actually measured Difference of difference ；
Step S2: when the nonlinear sonar works normally, a time domain waveform S of a 0-degree wave beam difference frequency signal is acquired and recorded Difference of difference (t)；
Step S3: based on the minimum detectable signal-to-noise ratio test experimental equipment, the transmitting matrix transmits an original frequency signal, the transmitting period is T1, the standard hydrophone receives a difference frequency signal, and the voltage effective value V of the difference frequency signal after filtering is recorded rms ；
Step S4: according to the effective value V of the filtered difference frequency signal voltage rms Actual measurement difference frequency equivalent sound source level SL Difference of difference And standard hydrophone sensitivity M, calculate the propagation loss TL;
step S5: the transmitting matrix stops transmitting, and the standard signal source outputs a difference frequency signal time domain waveform S Difference of difference (T) transmitting after passing through the power amplifier and the standard sound source, wherein the transmitting period is T2, the transmitting period T2 is smaller than T1 and meets the preset condition, equidistant targets appear in the 0-degree beam direction of the sonar image, the targets which are larger than the preset sonar operating distance index and are closest to the preset sonar operating distance index are taken as reference targets, and the difference frequency signal S output by the standard signal source is adjusted from large to small Difference of difference (t) when the reference object disappears on the sonar image, recording the effective value V2 of the difference frequency signal voltage output by the standard signal source rms The difference frequency signal sound source level emitted by the current standard sound source is the minimum detectable sound source level SL 1 ；
Step S6: stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the noise spectrum level NL in the background noise band;
step S7: from minimum detectable sound source level SL 1 Calculating a minimum detectable signal-to-noise ratio by using the background noise in-band noise spectrum level NL and the propagation loss;
the difference frequency signal equivalent sound source level measurement experimental equipment comprises a transmitter for transmitting an original frequency signal and a transmitting matrix, and is used for receiving a standard hydrophone, a standard filter and a standard oscilloscope of the difference frequency signal;
the minimum detectable signal to noise ratio test experimental equipment comprises: calculating propagation loss by using a transmitter for transmitting an original frequency signal, a transmitting matrix, a standard hydrophone for receiving a difference frequency signal, a standard filter and a standard oscilloscope; the method comprises the steps of utilizing a programmable signal source, a standard power amplifier and a standard sound source for transmitting a difference frequency signal, a receiving array and a receiving electronic cabin for receiving the difference frequency signal, a signal processor for detecting a target of the difference frequency signal, and a display console for displaying the target to calculate the minimum detectable signal to noise ratio.
Preferably, the difference frequency signal equivalent sound source level measurement experimental device adopts: a standard hydrophone is arranged under the auxiliary ship and at a position which is far from the underwater depth H, the horizontal distance between the standard hydrophone and the transmitting matrix is D1, and the transmitting matrix is arranged at the underwater depth H; the distance D1 is larger than the original frequency far-field distance, the original frequency far-field distance is larger than the difference frequency far-field distance, and the distance is not smaller than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, and the transmitting matrix and the standard hydrophone are in the same depth and are aligned with the 0-degree beam center.
Preferably, the measured difference frequency equivalent sound source stage SL Difference of difference The method adopts the following steps:
SL difference of difference ＝20lg(V1 rms )+20lg(D 1 )-M(1)
Wherein M represents the standard hydrophone sensitivity; v1 rms The effective value of the signal voltage of the difference frequency sound signal received by the standard hydrophone and the filter is represented, and D1 represents the horizontal distance between the transmitting matrix and the standard hydrophone.
Preferably, the minimum detectable signal to noise ratio test experimental equipment employs: the horizontal distance between a standard hydrophone and a transmitting matrix in the difference frequency signal equivalent sound source level measurement experimental equipment is adjusted to be a distance D2, and a standard sound source is arranged right below the standard hydrophone; setting a receiving matrix under the transmitting matrix; the distance D2 is larger than the difference frequency far field distance and is larger than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, the transmitting matrix and the standard hydrophone are in the same depth and the beam center of 0 degrees is aligned, and the receiving matrix and the standard sound source are in the same depth and the beam center of 0 degrees is aligned.
Preferably, the propagation loss TL employs:
TL＝SL difference of difference -20lg(V rms )+M(2)。
Preferably, the step S5 employs:
SL 1 ＝SL difference of difference +20lg(V2 rms /V1 rms )(3)。
Preferably, the minimum detectable signal-to-noise ratio employs:
SE＝SL 1 -NL-TL(4)。
the invention provides a nonlinear sonar minimum detectable signal-to-noise ratio test system, which comprises:
module M1: based on the difference frequency signal equivalent sound source level measurement experimental equipment, when the nonlinear sonar works normally, the difference frequency equivalent sound source level SL is actually measured Difference of difference ；
Module M2: when the nonlinear sonar works normally, a time domain waveform S of a 0-degree wave beam difference frequency signal is acquired and recorded Difference of difference (t)；
Module M3: based on the minimum detectable signal-to-noise ratio test experimental equipment, the transmitting matrix transmits an original frequency signal, the transmitting period is T1, the standard hydrophone receives a difference frequency signal, and the voltage effective value V of the difference frequency signal after filtering is recorded rms ；
Module M4: according to the effective value V of the filtered difference frequency signal voltage rms Actual measurement difference frequency equivalent sound source level SL Difference of difference And standard hydrophone sensitivity M, calculate the propagation loss TL;
module M5: the transmitting matrix stops transmitting, and the standard signal source outputs a difference frequency signal time domain waveform S Difference of difference (T) transmitting after passing through the power amplifier and the standard sound source, wherein the transmitting period is T2, the transmitting period T2 is smaller than T1 and meets the preset condition, equidistant targets appear in the 0-degree beam direction of the sonar image, the targets which are larger than the preset sonar operating distance index and are closest to the preset sonar operating distance index are taken as reference targets, and the difference frequency signal S output by the standard signal source is adjusted from large to small Difference of difference (t) recording the signature when the reference object disappears on the sonar imageEffective value V2 of difference frequency signal voltage output by quasi-signal source rms The difference frequency signal sound source level emitted by the current standard sound source is the minimum detectable sound source level SL 1 ；
Module M6: stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the noise spectrum level NL in the background noise band;
module M7: from minimum detectable sound source level SL 1 Calculating a minimum detectable signal-to-noise ratio by using the background noise in-band noise spectrum level NL and the propagation loss;
the difference frequency signal equivalent sound source level measurement experimental equipment comprises a transmitter for transmitting an original frequency signal and a transmitting matrix, and is used for receiving a standard hydrophone, a standard filter and a standard oscilloscope of the difference frequency signal;
the minimum detectable signal to noise ratio test experimental equipment comprises: calculating propagation loss by using a transmitter for transmitting an original frequency signal, a transmitting matrix, a standard hydrophone for receiving a difference frequency signal, a standard filter and a standard oscilloscope; the method comprises the steps of utilizing a programmable signal source, a standard power amplifier and a standard sound source for transmitting a difference frequency signal, a receiving array and a receiving electronic cabin for receiving the difference frequency signal, a signal processor for detecting a target of the difference frequency signal, and a display console for displaying the target to calculate the minimum detectable signal to noise ratio.
Preferably, the difference frequency signal equivalent sound source level measurement experimental device adopts: a standard hydrophone is arranged under the auxiliary ship and at a position which is far from the underwater depth H, the horizontal distance between the standard hydrophone and the transmitting matrix is D1, and the transmitting matrix is arranged at the underwater depth H; the distance D1 is larger than the original frequency far-field distance, the original frequency far-field distance is larger than the difference frequency far-field distance, and the distance is not smaller than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, the transmitting matrix and the standard hydrophone have the same depth, and the beam center of 0 DEG is aligned;
the measured difference frequency equivalent sound source level SL Difference of difference The method adopts the following steps:
SL difference of difference ＝20lg(V1 rms )+20lg(D 1 )-M(1)
Wherein M represents the sensitivity of a standard hydrophone；V1 rms The effective value of the signal voltage of the difference frequency sound signal received by the standard hydrophone and the filter is represented, and D1 represents the horizontal distance between the transmitting matrix and the standard hydrophone.
Preferably, the minimum detectable signal to noise ratio test experimental equipment employs: the horizontal distance between a standard hydrophone and a transmitting matrix in the difference frequency signal equivalent sound source level measurement experimental equipment is adjusted to be a distance D2, and a standard sound source is arranged right below the standard hydrophone; setting a receiving matrix under the transmitting matrix; the distance D2 is larger than the difference frequency far field distance and is larger than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of a transmitting signal of the transmitting matrix, the transmitting matrix and a standard hydrophone are in the same depth and the beam center of 0 degrees is aligned, and the receiving matrix and a standard sound source are in the same depth and the beam center of 0 degrees is aligned;
the propagation loss TL employs:
TL＝SL difference of difference -20lg(V rms )+M(2)
The module M5 employs:
SL 1 ＝SL difference of difference +20lg(V2 rms /V1 rms )(3)
The minimum detectable signal-to-noise ratio employs:
SE＝SL 1 -NL-TL(4)。
compared with the prior art, the invention has the following beneficial effects:
1. compared with the conventional system sonar minimum detectable signal-to-noise ratio test method, the method considers errors caused by larger differences between actual working signals and standard signals, and the test result is more accurate;
2. compared with the acting distance testing method, the method does not need to consider factors such as reverberation, hydrology, targets and the like, and greatly simplifies the sonar acting distance index verification method;
3. the test equipment is simple, the test method is high in operability, the test efficiency is improved, and the test cost is reduced.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
fig. 1 is a schematic diagram of a conventional system sonar minimum detectable signal-to-noise ratio measurement.
Fig. 2 is a schematic diagram of measuring equivalent sound source level of a nonlinear sonar difference frequency signal of the present invention.
Fig. 3 is a schematic diagram of a nonlinear sonar minimum detectable signal-to-noise ratio measurement of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
Example 1
The invention solves the problem that the prior method is difficult to accurately measure the minimum detectable signal-to-noise ratio of the nonlinear sonar; a nonlinear sonar minimum detectable signal-to-noise ratio test method is provided.
The invention provides a nonlinear sonar minimum detectable signal-to-noise ratio test method, which comprises the following steps:
step S1: based on the difference frequency signal equivalent sound source level measurement experimental equipment, when the nonlinear sonar works normally, the difference frequency equivalent sound source level SL is actually measured Difference of difference ；
Step S2: when the nonlinear sonar works normally, a time domain waveform S of a 0-degree wave beam difference frequency signal is acquired and recorded Difference of difference (t)；
Step S3: based on the minimum detectable signal-to-noise ratio test experimental equipment, the transmitting matrix transmits an original frequency signal, the transmitting period is T1, the standard hydrophone receives a difference frequency signal, and the voltage effective value V of the difference frequency signal after filtering is recorded rms ；
Step S4: according to the effective value V of the filtered difference frequency signal voltage rms Actual measurement difference frequency equivalent sound source level SL Difference of difference The sensitivity M of a standard hydrophone,calculating a propagation loss TL;
step S5: the transmitting matrix stops transmitting, and the standard signal source outputs a difference frequency signal time domain waveform S Difference of difference (t) (where standard signals are not applied, avoid E n1 、E n2 、E n3 、E n others ) Transmitting after passing through a power amplifier and a standard sound source, wherein the transmitting period is T2, the transmitting period T2 is far smaller than T1, equidistant target bright spots appear in the 0-degree beam direction of a sonar image, the target which is larger than a preset sonar operating distance index and is closest to the preset sonar operating distance index is taken as a reference object AA, and the difference frequency signal S output by the standard signal source is adjusted from large to small Difference of difference (t) when the target bright point AA on the sonar image disappears, recording the effective value V2 of the difference frequency signal voltage output by the standard signal source rms The difference frequency signal sound source level emitted by the current standard sound source is the minimum detectable sound source level SL 1 ；
Step S6: stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the noise spectrum level NL in the background noise band;
step S7: from minimum detectable sound source level SL 1 Calculating a minimum detectable signal-to-noise ratio by using the background noise in-band noise spectrum level NL and the propagation loss;
the difference frequency signal equivalent sound source level measurement experimental equipment comprises a transmitter for transmitting an original frequency signal and a transmitting matrix, and is used for receiving a standard hydrophone, a standard filter and a standard oscilloscope of the difference frequency signal;
the minimum detectable signal to noise ratio test experimental equipment comprises: calculating propagation loss by using a transmitter for transmitting an original frequency signal, a transmitting matrix, a standard hydrophone for receiving a difference frequency signal, a standard filter and a standard oscilloscope; the method comprises the steps of utilizing a programmable signal source, a standard power amplifier and a standard sound source for transmitting a difference frequency signal, a receiving array and a receiving electronic cabin for receiving the difference frequency signal, a signal processor for detecting a target of the difference frequency signal, and a display console for displaying the target to calculate the minimum detectable signal to noise ratio.
Specifically, the difference frequency signal equivalent sound source level measurement experimental device adopts: as shown in fig. 2, a standard hydrophone is arranged right below the auxiliary ship and at a position which is far from the underwater depth H, the horizontal distance between the standard hydrophone and the transmitting matrix is D1, and the transmitting matrix is arranged at the underwater depth H; the distance D1 is larger than the original frequency far-field distance, the original frequency far-field distance is larger than the difference frequency far-field distance, and the distance is not smaller than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, and the transmitting matrix and the standard hydrophone are in the same depth and are aligned with the 0-degree beam center.
Specifically, the measured difference frequency equivalent sound source stage SL Difference of difference The method adopts the following steps:
SL difference of difference ＝20lg(V1 rms )+20lg(D 1 )-M(1)
Wherein M represents the standard hydrophone sensitivity; v1 rms The effective value of the signal voltage of the difference frequency sound signal received by the standard hydrophone and the filter is represented, and D1 represents the horizontal distance between the transmitting matrix and the standard hydrophone.
Specifically, the minimum detectable signal to noise ratio test experimental equipment adopts: as shown in fig. 3, the horizontal distance between a standard hydrophone and a transmitting matrix in the difference frequency signal equivalent sound source level measurement experiment equipment is adjusted to be a distance D2, and a standard sound source is arranged right below the standard hydrophone; setting a receiving matrix under the transmitting matrix; the distance D2 is larger than the difference frequency far field distance and is larger than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, the transmitting matrix and the standard hydrophone are in the same depth and the beam center of 0 degrees is aligned, and the receiving matrix and the standard sound source are in the same depth and the beam center of 0 degrees is aligned.
Specifically, the propagation loss TL employs:
TL＝SL difference of difference -20lg(V rms )+M(2)。
Specifically, the step S5 employs:
SL 1 ＝SL difference of difference +20lg(V2 rms /V1 rms )(3)。
Specifically, the minimum detectable signal-to-noise ratio employs:
SE＝SL 1 -NL-TL(4)。
the invention provides a nonlinear sonar minimum detectable signal-to-noise ratio test system, which comprises:
module M1: based on the difference frequency signal equivalent sound source level measurement experimental equipment, when the nonlinear sonar works normally, the difference frequency equivalent sound source level SL is actually measured Difference of difference ；
Module M2: when the nonlinear sonar works normally, a time domain waveform S of a 0-degree wave beam difference frequency signal is acquired and recorded Difference of difference (t)；
Module M3: based on the minimum detectable signal-to-noise ratio test experimental equipment, the transmitting matrix transmits an original frequency signal, the transmitting period is T1, the standard hydrophone receives a difference frequency signal, and the voltage effective value V of the difference frequency signal after filtering is recorded rms ；
Module M4: according to the effective value V of the filtered difference frequency signal voltage rms Actual measurement difference frequency equivalent sound source level SL Difference of difference And standard hydrophone sensitivity M, calculate the propagation loss TL;
module M5: the transmitting matrix stops transmitting, and the standard signal source outputs a difference frequency signal time domain waveform S Difference of difference (t) (where standard signals are not applied, avoid E n1 、E n2 、E n3 、E n others ) Transmitting after passing through a power amplifier and a standard sound source, wherein the transmitting period is T2, the transmitting period T2 is far smaller than T1, equidistant target bright spots appear in the 0-degree beam direction of a sonar image, the target which is larger than a preset sonar operating distance index and is closest to the preset sonar operating distance index is taken as a reference object AA, and the difference frequency signal S output by the standard signal source is adjusted from large to small Difference of difference (t) when the target bright point AA on the sonar image disappears, recording the effective value V2 of the difference frequency signal voltage output by the standard signal source rms The difference frequency signal sound source level emitted by the current standard sound source is the minimum detectable sound source level SL 1 ；
Module M6: stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the noise spectrum level NL in the background noise band;
module M7: from minimum detectable sound source level SL 1 Calculating a minimum detectable signal-to-noise ratio by using the background noise in-band noise spectrum level NL and the propagation loss;
the difference frequency signal equivalent sound source level measurement experimental equipment comprises a transmitter for transmitting an original frequency signal and a transmitting matrix, and is used for receiving a standard hydrophone, a standard filter and a standard oscilloscope of the difference frequency signal;
the minimum detectable signal to noise ratio test experimental equipment comprises: calculating propagation loss by using a transmitter for transmitting an original frequency signal, a transmitting matrix, a standard hydrophone for receiving a difference frequency signal, a standard filter and a standard oscilloscope; the method comprises the steps of utilizing a programmable signal source, a standard power amplifier and a standard sound source for transmitting a difference frequency signal, a receiving array and a receiving electronic cabin for receiving the difference frequency signal, a signal processor for detecting a target of the difference frequency signal, and a display console for displaying the target to calculate the minimum detectable signal to noise ratio.
Specifically, the difference frequency signal equivalent sound source level measurement experimental device adopts: as shown in fig. 2, a standard hydrophone is arranged right below the auxiliary ship and at a position which is far from the underwater depth H, the horizontal distance between the standard hydrophone and the transmitting matrix is D1, and the transmitting matrix is arranged at the underwater depth H; the distance D1 is larger than the original frequency far-field distance, the original frequency far-field distance is larger than the difference frequency far-field distance, and the distance is not smaller than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, and the transmitting matrix and the standard hydrophone are in the same depth and are aligned with the 0-degree beam center.
Specifically, the measured difference frequency equivalent sound source stage SL Difference of difference The method adopts the following steps:
SL difference of difference ＝20lg(V1 rms )+20lg(D 1 )-M(1)
Wherein M represents the standard hydrophone sensitivity; v1 rms The effective value of the signal voltage of the difference frequency sound signal received by the standard hydrophone and the filter is represented, and D1 represents the horizontal distance between the transmitting matrix and the standard hydrophone.
Specifically, the minimum detectable signal to noise ratio test experimental equipment adopts: as shown in fig. 3, the horizontal distance between a standard hydrophone and a transmitting matrix in the difference frequency signal equivalent sound source level measurement experiment equipment is adjusted to be a distance D2, and a standard sound source is arranged right below the standard hydrophone; setting a receiving matrix under the transmitting matrix; the distance D2 is larger than the difference frequency far field distance and is larger than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, the transmitting matrix and the standard hydrophone are in the same depth and the beam center of 0 degrees is aligned, and the receiving matrix and the standard sound source are in the same depth and the beam center of 0 degrees is aligned.
Specifically, the propagation loss TL employs:
TL＝SL difference of difference -20lg(V rms )+M(2)。
Specifically, the module M5 employs:
SL 1 ＝SL difference of difference +20lg(V2 rms /V1 rms )(3)。
Specifically, the minimum detectable signal-to-noise ratio employs:
SE＝SL 1 -NL-TL(4)。
example 2
Example 2 is a preferred example of example 1
The test is carried out according to a nonlinear sonar minimum detectable signal-to-noise ratio test method, in the embodiment, the nonlinear sonar has an original frequency far-field distance of about 47m, a difference frequency far-field distance of about 12m, an equivalent end-shooter length of about 100m and a cavitation depth of about 8m.
Step 1, measuring equivalent sound source level of difference frequency signals, wherein the deployment of test equipment is shown in figure 2, and the distance D is the distance 1 The depth H is 10m and 100m, the transmitting matrix and the standard hydrophone are in the same depth and the beam center of 0 DEG is aligned, when the nonlinear sonar works normally, the difference frequency signal equivalent sound source level SL is actually measured Difference of difference ，SL Difference of difference ＝203.66dB；
Step 2, recording difference frequency signal waveforms, and collecting and recording 0-degree wave beam difference frequency signal waveforms S difference (t) when the nonlinear sonar works normally;
step 3, measuring the minimum detectable signal-to-noise ratio, wherein the equipment deployment is shown in fig. 3, and the distance D is the distance 2 25m, and a depth H of 10m;
step 4, transmitting the primary frequency signal by the transmitting matrix, and transmitting the period T 1 For 1s, the standard hydrophone receives the difference frequency signal, records and filtersThe effective value Vrms of the voltage of the difference frequency signal after the wave is carried out, vrms=9×10 -6 V；
Step 5, calculating the propagation loss TL=30.37 dB according to the standard hydrophone sensitivity M= -214.2 dB;
step 6, stopping transmitting by the transmitting matrix, and transmitting the difference frequency signal S by the standard sound source Difference of difference (T), emission period T 2 Observing the sonar interface at 0.1S, and adjusting S from large to small by taking a target which is larger than the action distance index and is closest to the action distance index as a reference object Difference of difference (t) Sound source stage, when the target disappears, record the S Difference of difference (t) Sound Source level being minimum detectable Sound Source level SL 1 ，SL 1 ＝88.98(dB)；
Step 7, stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the in-band noise spectrum level NL=88.25 (dB) of the background noise;
and 8, calculating the minimum detectable signal-to-noise ratio SE= -29.64dB.
In this embodiment, the minimum detectable signal to noise ratio index requirement is-26 dB, and the measured value meets the index requirement.
In the description of the present application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, merely to facilitate description of the present application and simplify the description, and do not indicate or imply that the devices or elements being referred to must have a specific orientation, be configured and operated in a specific orientation, and are not to be construed as limiting the present application.
Those skilled in the art will appreciate that the systems, apparatus, and their respective modules provided herein may be implemented entirely by logic programming of method steps such that the systems, apparatus, and their respective modules are implemented as logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc., in addition to the systems, apparatus, and their respective modules being implemented as pure computer readable program code. Therefore, the system, the apparatus, and the respective modules thereof provided by the present invention may be regarded as one hardware component, and the modules included therein for implementing various programs may also be regarded as structures within the hardware component; modules for implementing various functions may also be regarded as being either software programs for implementing the methods or structures within hardware components.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily without conflict.
Claims (10)
1. The nonlinear sonar minimum detectable signal-to-noise ratio testing method is characterized by comprising the following steps of:
step S1: based on the difference frequency signal equivalent sound source level measurement experimental equipment, when the nonlinear sonar works normally, the difference frequency equivalent sound source level SL is actually measured Difference of difference ；
Step S2: when the nonlinear sonar works normally, a time domain waveform S of a 0-degree wave beam difference frequency signal is acquired and recorded Difference of difference (t)；
Step S3: based on the minimum detectable signal-to-noise ratio test experimental equipment, the transmitting matrix transmits an original frequency signal, the transmitting period is T1, the standard hydrophone receives a difference frequency signal, and the voltage effective value V of the difference frequency signal after filtering is recorded rms ；
Step S4: according to the effective value V of the filtered difference frequency signal voltage rms Actual measurement difference frequency equivalent sound source level SL Difference of difference And standard hydrophone sensitivity M, calculate the propagation loss TL;
step S5: the transmitting matrix stops transmitting, and the standard signal source outputs a difference frequency signal time domain waveform S Difference of difference (T) transmitting after passing through the power amplifier and the standard sound source, wherein the transmitting period is T2, the transmitting period T2 is smaller than T1 and meets the preset condition, equidistant targets appear in the 0-degree beam direction of the sonar image, the targets which are larger than the preset sonar operating distance index and are closest to the preset sonar operating distance index are taken as reference targets, and the standard information is adjusted from large to smallDifference frequency signal S output by number source Difference of difference (t) when the reference object disappears on the sonar image, recording the effective value V2 of the difference frequency signal voltage output by the standard signal source rms The difference frequency signal sound source level emitted by the current standard sound source is the minimum detectable sound source level SL 1 ；
Step S6: stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the noise spectrum level NL in the background noise band;
step S7: from minimum detectable sound source level SL 1 Calculating a minimum detectable signal-to-noise ratio by using the background noise in-band noise spectrum level NL and the propagation loss;
the difference frequency signal equivalent sound source level measurement experimental equipment comprises a transmitter for transmitting an original frequency signal and a transmitting matrix, and is used for receiving a standard hydrophone, a standard filter and a standard oscilloscope of the difference frequency signal;
the minimum detectable signal to noise ratio test experimental equipment comprises: calculating propagation loss by using a transmitter for transmitting an original frequency signal, a transmitting matrix, a standard hydrophone for receiving a difference frequency signal, a standard filter and a standard oscilloscope; the method comprises the steps of utilizing a programmable signal source, a standard power amplifier and a standard sound source for transmitting a difference frequency signal, a receiving array and a receiving electronic cabin for receiving the difference frequency signal, a signal processor for detecting a target of the difference frequency signal, and a display console for displaying the target to calculate the minimum detectable signal to noise ratio.
2. The method for testing the minimum detectable signal-to-noise ratio of the nonlinear sonar according to claim 1, wherein the difference frequency signal equivalent sound source level measurement experimental equipment adopts: a standard hydrophone is arranged under the auxiliary ship and at a position which is far from the underwater depth H, the horizontal distance between the standard hydrophone and the transmitting matrix is D1, and the transmitting matrix is arranged at the underwater depth H; the distance D1 is larger than the original frequency far-field distance, the original frequency far-field distance is larger than the difference frequency far-field distance, and the distance is not smaller than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, and the transmitting matrix and the standard hydrophone are in the same depth and are aligned with the 0-degree beam center.
3. The method for testing the minimum detectable signal to noise ratio of the nonlinear sonar according to claim 1, wherein the measured difference frequency equivalent sound source level SL Difference of difference The method adopts the following steps:
SL difference of difference ＝20lg(V1 rms )+20lg(D 1 )-M(1)
Wherein M represents the standard hydrophone sensitivity; v1 rms The effective value of the signal voltage of the difference frequency sound signal received by the standard hydrophone and the filter is represented, and D1 represents the horizontal distance between the transmitting matrix and the standard hydrophone.
4. The nonlinear sonar minimum detectable signal to noise ratio test method of claim 2, wherein the minimum detectable signal to noise ratio test experimental equipment employs: the horizontal distance between a standard hydrophone and a transmitting matrix in the difference frequency signal equivalent sound source level measurement experimental equipment is adjusted to be a distance D2, and a standard sound source is arranged right below the standard hydrophone; setting a receiving matrix under the transmitting matrix; the distance D2 is larger than the difference frequency far field distance and is larger than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, the transmitting matrix and the standard hydrophone are in the same depth and the beam center of 0 degrees is aligned, and the receiving matrix and the standard sound source are in the same depth and the beam center of 0 degrees is aligned.
5. The nonlinear sonar minimum detectable signal-to-noise ratio test method of claim 1, wherein the propagation loss TL employs:
TL＝SL difference of difference -20lg(V rms )+M(2)。
6. The method for testing the minimum detectable signal-to-noise ratio of the nonlinear sonar according to claim 1, wherein said step S5 uses:
SL 1 ＝SL difference of difference +20lg(V2 rms /V1 rms )(3)；
Wherein V1 rms Representing the difference frequency acoustic signal through standard hydrophone and filteringThe signal voltage effective value after the receiver receives.
7. The method for testing the minimum detectable signal-to-noise ratio of the nonlinear sonar according to claim 1, wherein the minimum detectable signal-to-noise ratio adopts:
SE＝SL 1 -NL-TL(4)。
8. a non-linear sonar minimum detectable signal to noise ratio test system comprising:
module M1: based on the difference frequency signal equivalent sound source level measurement experimental equipment, when the nonlinear sonar works normally, the difference frequency equivalent sound source level SL is actually measured Difference of difference ；
Module M2: when the nonlinear sonar works normally, a time domain waveform S of a 0-degree wave beam difference frequency signal is acquired and recorded Difference of difference (t)；
Module M3: based on the minimum detectable signal-to-noise ratio test experimental equipment, the transmitting matrix transmits an original frequency signal, the transmitting period is T1, the standard hydrophone receives a difference frequency signal, and the voltage effective value V of the difference frequency signal after filtering is recorded rms ；
Module M4: according to the effective value V of the filtered difference frequency signal voltage rms Actual measurement difference frequency equivalent sound source level SL Difference of difference And standard hydrophone sensitivity M, calculate the propagation loss TL;
module M5: the transmitting matrix stops transmitting, and the standard signal source outputs a difference frequency signal time domain waveform S Difference of difference (T) transmitting after passing through the power amplifier and the standard sound source, wherein the transmitting period is T2, the transmitting period T2 is smaller than T1 and meets the preset condition, equidistant targets appear in the 0-degree beam direction of the sonar image, the targets which are larger than the preset sonar operating distance index and are closest to the preset sonar operating distance index are taken as reference targets, and the difference frequency signal S output by the standard signal source is adjusted from large to small Difference of difference (t) when the reference object disappears on the sonar image, recording the effective value V2 of the difference frequency signal voltage output by the standard signal source rms The difference frequency signal sound source level emitted by the current standard sound source is the minimum detectable sound source level SL 1 ；
Module M6: stopping transmitting the standard sound source, analyzing the background noise of the receiving matrix, and recording the noise spectrum level NL in the background noise band;
module M7: from minimum detectable sound source level SL 1 Calculating a minimum detectable signal-to-noise ratio by using the background noise in-band noise spectrum level NL and the propagation loss;
the difference frequency signal equivalent sound source level measurement experimental equipment comprises a transmitter for transmitting an original frequency signal and a transmitting matrix, and is used for receiving a standard hydrophone, a standard filter and a standard oscilloscope of the difference frequency signal;
the minimum detectable signal to noise ratio test experimental equipment comprises: calculating propagation loss by using a transmitter for transmitting an original frequency signal, a transmitting matrix, a standard hydrophone for receiving a difference frequency signal, a standard filter and a standard oscilloscope; the method comprises the steps of utilizing a programmable signal source, a standard power amplifier and a standard sound source for transmitting a difference frequency signal, a receiving array and a receiving electronic cabin for receiving the difference frequency signal, a signal processor for detecting a target of the difference frequency signal, and a display console for displaying the target to calculate the minimum detectable signal to noise ratio.
9. The nonlinear sonar minimum detectable signal-to-noise ratio test system of claim 8, wherein the difference frequency signal equivalent sound source level measurement experiment device employs: a standard hydrophone is arranged under the auxiliary ship and at a position which is far from the underwater depth H, the horizontal distance between the standard hydrophone and the transmitting matrix is D1, and the transmitting matrix is arranged at the underwater depth H; the distance D1 is larger than the original frequency far-field distance, the original frequency far-field distance is larger than the difference frequency far-field distance, and the distance is not smaller than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of the transmitting signals of the transmitting matrix, the transmitting matrix and the standard hydrophone have the same depth, and the beam center of 0 DEG is aligned;
the measured difference frequency equivalent sound source level SL Difference of difference The method adopts the following steps:
SL difference of difference ＝20lg(V1 rms )+20lg(D 1 )-M(1)
Wherein M represents the standard hydrophone sensitivity; v1 rms Representing the difference frequency acoustic signal through standard hydrophone and filteringAnd D1 represents the horizontal distance between the transmitting matrix and the standard hydrophone.
10. The non-linear sonar minimum detectable signal to noise ratio test system of claim 9, wherein the minimum detectable signal to noise ratio test experimental equipment employs: the horizontal distance between a standard hydrophone and a transmitting matrix in the difference frequency signal equivalent sound source level measurement experimental equipment is adjusted to be a distance D2, and a standard sound source is arranged right below the standard hydrophone; setting a receiving matrix under the transmitting matrix; the distance D2 is larger than the difference frequency far field distance and is larger than the equivalent end-shooting array length of the nonlinear effect of the nonlinear sonar; the depth H is greater than the depth of cavitation of a transmitting signal of the transmitting matrix, the transmitting matrix and a standard hydrophone are in the same depth and the beam center of 0 degrees is aligned, and the receiving matrix and a standard sound source are in the same depth and the beam center of 0 degrees is aligned;
the propagation loss TL employs:
TL＝SL difference of difference -20lg(V rms )+M(2)
The module M5 employs:
SL 1 ＝SL difference of difference +20lg(V2 rms /V1 rms )(3)
The minimum detectable signal-to-noise ratio employs:
SE＝SL 1 -NL-TL(4)；
wherein V1 rms And the effective value of the signal voltage of the difference frequency sound signal received by the standard hydrophone and the filter is represented.
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