CN103364779B - Fixed forwarding strength-based target echo wave strength measurement method and fixed forwarding strength-based target echo wave strength measurement system - Google Patents
Fixed forwarding strength-based target echo wave strength measurement method and fixed forwarding strength-based target echo wave strength measurement system Download PDFInfo
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Abstract
The invention discloses a fixed forwarding strength-based target echo wave strength measurement method and a fixed forwarding strength-based target echo wave strength measurement system. The target strength can be taken as prior information for further acquiring the distance, the orientation and the size of an object to be measured. The method comprises the following steps: step 101), measurement samples of all periods are acquired according to a set period, wherein each measurement sample comprises three parts of data: echo wave data recorded by a main measurement platform subsystem, incident signal data stored by a measurement platform subsystem of the object to be measured, and forwarded signal data; step 102), after the acquired measurement samples are sampled, subsequent data processing operation is performed and the target strength is obtained, wherein the subsequent data processing operation is specifically step 102-1) of obtaining the electric signal amplitude Ue of an echo wave, the electrical signal amplitude Ua of a forwarded signal and the electrical signal amplitude Ui of an incident wave according to the measurement sample data.
Description
Technical Field
The invention belongs to the field of target echo intensity measurement, and relates to a target echo intensity measurement method and a target echo intensity measurement system based on fixed forwarding intensity.
Background
In the prior art, various means of electromagnetic waves and sound waves are used for measuring and estimating the distance, the direction and the size of a target, and the method is widely applied to various fields. For example, nondestructive inspection in industry, fishing in fishery, various types of ultrasonic inspection in medical treatment, and radar and sonar in the field of defense. The basic principle is that a certain fluctuation signal (such as electromagnetic wave or mechanical wave) is actively transmitted, after the fluctuation signal propagates in a medium and reaches a target, the fluctuation can be reflected on the surface of the target due to the heterogeneity of the target and the environmental medium, a sensor array is used for receiving the reflection signal, and the distance, the direction, the size and the like of the target to be measured can be estimated according to the intensity of the reflection signal and the delay time of returning to each sensor.
However, to accurately perform the above measurement and estimation, some a priori knowledge of the target to be measured is required. Among them, the most important one is the so-called target intensity. Target intensity is the ratio of the reflected signal intensity to the incident signal intensity at a unit distance from the measured target, usually logarithmically:
wherein E isrAnd EiThe reflected wave intensity and the incident wave intensity are expressed in logarithmic form, respectively, as shown in fig. 3.
Because of the great significance of the application, some target strength measuring methods are widely applied. Two most representative prior art methods for measuring the intensity of an object are described below.
1. Direct measurement:
because direct measurement of the actual target per unit distance is impractical, the reasons include, but are not limited to, the following:
1) the actual target may be very bulky, and it is wrong to equate it as a point for close range measurement regardless of the dimensions of the actual target.
2) The echo intensities exhibited by the target at close range and the significant difference at far range may be significant, and measurements at close range should not be used, as many practical applications are for long range measurements.
3) Under many measurement conditions, measuring over a unit distance has practical operational difficulties.
Therefore, the measurement of the actual target is usually performed at a long distance. The signals are transmitted over a long distance and the echo signals are received over a long distance, both of which are, of course, normalized to the incident signal strength and the reflected signal strength per unit distance, as defined by the target strength, as shown in figure 3.
Ei＝SL-TL1 (2)
Er＝EL+TL2 (3)
Wherein, SL: the intensity of the transmitted wave; EL: the intensity of the echo; TL1: propagation loss to and from the source of the fluctuating signal to the target being measured; TL2: propagation loss of the return path (from the measured object to the source of the fluctuating signal).
Substituting the formulas (2) and (3) into the formula (1) to obtain a target intensity calculation formula of a direct measurement method,
TS＝EL-SL+TL1+TL2 (4)
the physical quantities to be measured or estimated are four: emission intensity SL of fluctuating signal source, received echo intensity EL, forward propagation loss TL1And return propagation loss TL2. Error of measurement of target intensity ETSThe influence of the following factors,
1)EEL: echo measurement errors, mainlyDepending on the accuracy of the sensitivity of the receiving sensor;
2)ESL: calibrating errors of the intensity of the transmitted signals;
3)ETL: the error is estimated from the round-trip propagation loss of the fluctuating signal.
ETS＝EEL+ESL+ETL (5)
It is clear that to control the measurement error of the direct measurement method, careful calibration of the transmitted signal strength, the sensitivity of the receiving sensor, and accurate estimation of the propagation loss of the channel are required.
The physical meaning of the direct measurement method is most direct, but under the complex channel measurement condition, the channel propagation loss is difficult to estimate accurately. This often results in measurements with high uncertainty and discreteness. Therefore, in the practice of test measurement, the following echo-forwarding measurement method is proposed.
2. Echo retransmission measuring method
The echo repeating measurement method is to install an echo repeater on a measured object, wherein the repeater has the functions of receiving and transmitting a fluctuating signal at the same time. After receiving the fluctuation signal, the repeater calculates the signal intensity, adds a fixed multiple of amplification gain, and forwards the signal back. The retransmitted signal is also typically delayed in the time domain in order to distinguish it from the reflected echoes of the target. Thus, the information of the strength of the incident signal is actually contained in the retransmitted signal, and the working principle of the measuring system is shown in fig. 4.
By definition,
EL＝Ei+TS-TL2 (6)
on the other hand, the received strength of the retransmitted signal,
Ea＝Ei+K-TL2 (7)
wherein,Ea: received forwarded signal strength; k: a fixed forwarding gain of the transponder.
Subtracting the expressions (6) and (7), and then sorting to obtain,
wherein, Ue: the electric signal intensity of the echo at the signal receiving end; u shapea: the electrical signal strength of the forwarded signal at the signal receiving end.
That is, at the receiving end of the measurement, the target intensity can be calculated by directly comparing the intensities of the echo signal and the retransmission signal. When the signal is received, the measurement error caused by the sensitivity of the sensor and the estimation error of the propagation loss are mutually offset, and the acquisition, analysis and processing of the electric signal can realize relatively higher measurement precision. Thus, the measurement error E of the target intensityTSMainly depending on the error in the transponder gain. The error in the transponder gain depends on the sensitivity error of the receiving sensor on the transponder and the control error of the transponder gain.
ETS≈EK＝EM+EaSL (9)
Wherein E isM: the transponder receives the sensor sensitivity error; eaSL: a repeater forwarding strength error;
it can be seen that the use of echo-forward measurements eliminates the need for precise calibration of the main transmit transducer transmit signal strength and the sensor array receive sensitivity. Only a single receiving sensor and a repeater transducer on the echo repeater device need to be accurately metered for transmitted signal strength. The conventional echo forwarding method described above has many advantages, but also has some disadvantages.
First, the conventional echo forwarding measurement method uses fixed gain forwarding, and the forwarding strength varies with the strength of the incident signal. This results in the possibility that the resulting forwarding intensity may vary over a relatively large range, and therefore requires accurate calibration of the forwarding transducer over a relatively large intensity range, which is labor intensive and also accuracy is not easily controlled. From practical results, this is a major bottleneck factor limiting the accuracy of the echo-forwarding method measurement.
Secondly, the conventional echo forwarding device uses a hardware circuit to judge the intensity of the incident signal, so that the conventional echo forwarding device is often only suitable for processing single-frequency pulse signals. Although complex signal processing can be realized theoretically, the cost is high, and the specificity is too strong to adapt to the changing complex signal.
The invention provides an improved measuring method aiming at target strength. The precision and the efficiency of measurement are obviously improved. The measurement and estimation of the target by using the fluctuation signal are widely applied in various fields. The method has obvious practical significance for improving basic scientific research measurement capability in the fields.
Disclosure of Invention
The invention aims to overcome the defects of the traditional echo forwarding measurement system, and provides a target echo intensity measurement method and a target echo intensity measurement system based on fixed forwarding intensity.
In order to achieve the above object, the present invention provides a target echo intensity measurement method based on fixed forwarding intensity, where the target intensity can be used as prior information for further obtaining the distance, orientation, and size of a target to be measured, and the method includes:
step 101) obtaining measurement samples of each period according to a certain set period, wherein each measurement sample comprises three parts of data: echo data recorded by the main measuring platform subsystem, incident signal data stored by the measuring platform subsystem of the target to be measured and forwarded signal data;
step 102) sampling the obtained measurement sample, and then performing subsequent data processing to obtain target intensity, wherein the subsequent data processing specifically comprises the following steps:
step 102-1) acquiring the electric signal amplitude U of the echo according to the measurement sample dataeAmplitude U of electric signal of forwarding signalaAnd the amplitude U of the electrical signal of the incident waveiThe method comprises the following specific steps:
according to echo data recorded by a main measuring platform in a measuring sample, calculating an electric signal effective value U corresponding to an echo by adopting the following formulae，
Wherein, TeFor the time length of the echo signal pulse, peInstantaneous amplitude in volts of the echo data recorded for the primary measurement platform;
according to the main measuring platform in the measuring sampleThe recorded forwarding signal data adopts the following formula to calculate the electric signal effective value U corresponding to the forwarding signala，
Wherein, TaFor the duration of the signal pulse, paInstantaneous amplitude of the forwarded signal, in volts, recorded for the primary measurement platform;
according to incident wave data recorded by a target-borne measuring platform in a measuring sample, calculating an electric signal effective value U corresponding to the incident wave at the target by adopting the following formulai，
Wherein, TiFor forwarding signal pulsesLength of time of piInstantaneous amplitude of the incident wave signal recorded for the target borne measurement platform, in volts, and said piAcquiring a value by additionally arranging acquisition and recording equipment on a measured target;
step 102-2) calculating the target echo intensity Ts of a certain measurement sample according to the values of the parameters obtained in the previous step and the following formula, wherein SLaIs a fixed signal forwarding strength, MaSensitivity of the receiving sensor on the object to be measured:
step 102-3) repeating the two steps to complete the calculation processing of all the measurement samples to obtain the target echo intensities TS corresponding to all the measurement samples; and performing accepting and weighting processing on all target echo intensities TS to obtain a final target intensity result.
In the above technical solution, the step 101) specifically includes: in a measurement period, the transducer of the main measurement platform transmits a measurement signal to a target to be measured; the measuring signal is transmitted to the target to be measured, then a part of signal energy is reflected by the target to be measured, and meanwhile, the equipment on the target to be measured collects and records the waveform p of the incident signali；
After a certain fixed time delay, the target forwards a signal to the main measurement platform through the repeater; the main measuring platform receives the echo signal p reflected by the targeteAnd delayed forwarded signal paAnd storing the signal waveform.
In the above technical solution, before the step 101), the method further comprises the following steps: and a step for synchronizing the main measuring platform and the measuring platform subsystem of the object to be measured by using the synchronous source.
Based on the above method, the present invention further provides a target echo intensity measurement system based on fixed forwarding intensity, which is characterized in that the system comprises: the system comprises a main measuring platform subsystem, a measuring platform subsystem of a target to be measured and a data processing subsystem;
the main measurement platform subsystem is used for controlling and transmitting an incident measurement signal to a target to be measured, receiving and storing an echo signal reflected by the target to be measured and a forwarding signal of a forwarding transducer at the same time, and the stored data is used for subsequent data processing;
the measurement platform subsystem of the target to be measured is used for controlling and transmitting a forwarding measurement signal to the main measurement platform subsystem, receiving and storing an incident signal at the target to be measured, and the stored data is used for subsequent data processing;
the data processing subsystem respectively acquires measurement data from the stored data parts of the two subsystems to form measurement samples, and then calculates the target strength according to the measurement samples;
wherein the measurement sample comprises: echo data recorded by the main measuring platform subsystem, incident signal data stored by the measuring platform subsystem of the target to be measured and forwarded signal data.
In the above technical solution, the main measurement platform subsystem further includes: the device comprises a control unit, a programmable signal generating unit, a synchronous signal receiving unit, a collecting and recording unit, a power amplifier unit, a first transmitting transducer and a receiving sensor;
the programmable signal generating unit is used for generating a signal waveform transmitted to a target to be detected;
the synchronous signal receiving unit is used for receiving a synchronous signal transmitted by a synchronous source;
the receiving sensor is used for receiving echo electric signals and forwarding electric signals reflected by the target to be detected and transmitting the electric signals to the data acquisition and recording unit;
the acquisition and recording unit is used for converting the electric signals into digital signals and storing the digital signals, and is also connected with the data processing subsystem to input the stored signals into the digital processing subsystem for processing;
and the first transmitting transducer is used for transmitting a measuring signal to a target to be measured.
In the above technical solution, the measurement subsystem of the target to be measured further includes: the device comprises a control unit, an echo transponder, a synchronous signal receiving unit and a data acquisition and recording unit;
the acquisition recording unit is used for converting the electric signals into digital signals and storing the digital signals on corresponding storage media for subsequent data processing;
the control unit is used for controlling the working time sequence of the measurement subsystem of the target to be measured and the emission of the forwarding signal;
the echo transponder is used for exciting the transponder transducer to complete signal retransmission;
the synchronous receiving unit is used for receiving a synchronous signal of a synchronous source;
the echo transponder selects and outputs a forwarding signal with fixed strength through the signal generating unit according to the frequency band and the signal type of the incident signal, and excites a forwarding transducer in the echo transponder after the forwarding signal is amplified by a power amplifier, so that the incident signal is forwarded.
In the above technical solution, the echo repeater further includes: the signal generating unit, the receiving sensor, the second transmitting transducer and the power amplifier;
the receiving sensor is used for receiving an incident signal which is transmitted by the first transmitting transducer and comes from a transmission channel and transmitting an electric signal to the data acquisition and recording unit;
the second transmitting transducer is used for receiving the excitation from the power amplifier, converting the electric signal into corresponding wave energy and radiating the wave energy, thereby completing the forwarding of the signal;
the power amplifier is used for amplifying the original electric signal from the signal generating unit and then exciting the second transmitting transducer;
the receiving sensor and the second transmitting transducer are arranged on a target shell to be detected, wherein the target shell can directly receive incident signal radiation transmitted by a wireless channel and transmitted by the main measuring platform.
Optionally, the synchronization source uses a GPS signal as the synchronization source.
The differences are mainly reflected in that:
1. the data recording equipment is additionally arranged on the measured target, and the recorded data is analyzed and processed afterwards, so that more accurate incident signal intensity can be obtained, and the system can be suitable for various complex and changeable signal forms.
2. The repeater employs a fixed forwarding strength. The target is additionally provided with the recording equipment, so that the transponder can transmit signals with fixed intensity to finish measurement without carrying intensity information of incident signals. The requirement on the response linearity of the transponder is reduced, the work of calibration in a large range of emission intensity level is simplified into the work of calibration on a fixed emission intensity level, the calibration workload is greatly reduced, and the measurement precision and reliability are indirectly improved. The system operating principle of the fixed forwarding strength measurement method is shown in fig. 5.
As can be seen from the above description of the method, the fixed retransmission strength retransmission measurement method is improved in the following aspects compared with the conventional echo retransmission measurement method:
1. the requirement for the linearity of the response of the transponder is eliminated. The point-by-point calibration work required in a larger intensity range is simplified into the calibration work on a fixed intensity, so that the calibration work load is reduced, and the measurement precision and reliability are indirectly improved. According to estimation, under the same calibration condition, the calibration workload of the new method can be reduced by one order of magnitude, and the workload of a measurement system user is greatly reduced.
1. The improved measurement method does not need to use hardware to calculate the intensity of the incident signal in real time, but adopts an alternative mode of processing the recorded data afterwards, so that various complex signal processing means can be used, complex signals in various forms can be flexibly processed, the application range of the system is greatly expanded, the life cycle of the system is obviously prolonged, and the cost performance of the system is improved.
3. In the traditional measuring method, only one measuring pulse at a single frequency can be measured in one measuring period, so that the measuring efficiency is low, and the required measuring period is long. The new measuring method allows measuring signals with different frequencies and different modulation forms to be transmitted densely in one measuring period, and the signals can be effectively distinguished through frequency diversity or coding diversity, so that the working efficiency of the measuring system is greatly improved.
4. The transponder adopts fixed emission intensity, reduces the requirement on the transponder, thereby reducing the hardware complexity of the part arranged on the target shell, being beneficial to the miniaturization and the improvement of the stability, and being convenient for installation and use outside the measured target shell.
Although the additional cost is increased by additionally arranging a set of signal acquisition and recording device on the measured object, the space cost and the economic cost of additionally arranging such a set of recording device are almost negligible relative to the obvious gains after improvement due to the continuous emergence of high-performance, high-integration and low-price acquisition and recording products in recent years.
Drawings
FIG. 1 is a block diagram of a portion of a fixed forward intensity target echo intensity measurement system employed in the present invention;
FIG. 2 is an overall block diagram of the fixed forward strength target echo strength measurement system of the present invention;
FIG. 3 is a schematic illustration of a prior art direct measurement of target intensity;
FIG. 4 is a schematic illustration of a prior art echo-retransmission measurement of target intensity;
figure 5 is a schematic diagram of the improved echo-retransmission measurement of the present invention.
Detailed Description
The invention is described in detail below with reference to specific embodiments and the attached drawings.
The invention adopts an improved echo forwarding method to obtain the target strength. The method is characterized in that a data recording device is additionally arranged on a measured target, recorded data are analyzed afterwards, more accurate incident signal intensity can be obtained, and the method is suitable for various signal forms. The fixed emission intensity is adopted for the transmitting signals, the calibration work which needs to be within a larger intensity range is simplified into the calibration work on the fixed intensity, the workload is greatly reduced, the measurement precision is improved, and the working principle of the measurement system is shown in figure 5. It is clear that,
EL＝Er-TL2 (10)
Ea＝SLa-TL2 (11)
wherein SLa: fixed forwarding strength of the echo repeater.
Subtracting the expressions (10) and (11), and then sorting to obtain,
Er＝EL-Ea+SLa (12)
substituting the formula (12) into the formula (1),
the expression of the measurement result is as follows:
(13)
wherein,
Ma: receive sensor sensitivity of the transponder;
SLa: of repeatersThe forwarding strength is fixed.
Ue: the electrical signal strength of the echo at the receiving end. The definition of the method is various and should be selected according to actual conditions. The present description takes as an example the root mean square value of the power integration within the pulse length, i.e. the effective value, to calculate.
TeFor the time length of the echo signal pulse, peIs the instantaneous amplitude of the echo signal, in volts;
Ua: the electric signal intensity of the forwarding signal at the receiving end adopts the same definition mode as Ue，
TaFor the duration of the signal pulse, paIs the instantaneous amplitude of the echo signal, in volts;
Ui: the definition mode adopted by the echo transponder to receive the electric signal intensity of the incident signal is the same as Ue，
TiFor the duration of the signal pulse, piThe instantaneous amplitude of the echo signal is in volts.
Because the measurement error range of the effective value of the electric signal is usually within 0.2dB, the measurement error range can be ignored compared with the measurement accuracy requirement of 2-3 dB of the whole measurement system. Therefore, the error of the FRSL method depends mainly on the sensitivity error of the receiving sensor on the transponder and the scaling error of the fixed forwarding strength.
ETS≈EM+EaSL (17)
Wherein E isM: the transponder receives the sensor sensitivity error; eaSL: the repeater fixes the forwarding strength error.
Although the error expressions of the FRSL method are the same as those of the conventional echo forwarding method (see expressions (17) and (9)), the calibration work required to be performed point by point within a large intensity range is simplified to the calibration work on a fixed intensity, so that the calibration work is greatly reduced, and the measurement accuracy and reliability are indirectly improved.
In summary, the improved echo forwarding measurement method not only retains the advantages of the conventional echo forwarding measurement method, but also overcomes the important disadvantages thereof. The calibration workload is obviously reduced, and the measurement precision and reliability are improved.
The invention provides a method for obtaining the strength of a target to be measured, which is used as prior information for further obtaining the distance, the direction and the size of the target to be measured, the method comprises the following steps:
step 101) synchronizing the synchronization units of the main measurement platform and the target platform by using a GPS (or other synchronization sources), so as to ensure that the measurement subsystems of the two places are in a strictly synchronous working mode in the whole measurement process. The working situation of the system is shown in a schematic block diagram of the measuring state of the target echo intensity measuring system with fixed forwarding intensity in figure 1.
Step 102) the system obtains a plurality of measurement samples according to a certain fixed work cycle. In a measurement period, transducer signal transmission of a main measurement platform is completed in sequence; waiting for the signal to propagate on the way; the measured target receives the signal radiation and then reflects the signal, and the waveform of the incident signal is recorded on an external storage medium; after a certain fixed time delay, the target transponder forwards the signal; and finally, the main measuring platform receives the echo signal of the target and the delayed retransmission signal, and records the signal waveform on an external storage medium. In the following, taking a certain measurement system actually used as an example, the working sequence and flow of the measurement will be specifically described. The selection of the specific time parameters in the time sequence varies depending on the propagation speed of the measurement signal used, the measurement distance, and the measurement target, and is used for illustration only, and the implementation of the method is not necessarily limited to the specific parameters described below.
In an actual measurement system using the method, a duty cycle of taking a measurement sample is 4 seconds, and the measurement is performed in the following sequence.
And at the moment of 1.0 second, the synchronous pulse arrives, the measurement platform carrier system starts the power amplifier, and then the measurement signal is transmitted. During this time, the echo forwarding device of the target subsystem is still in a receiving state, and the incident signal is recorded.
And at the moment of 2.1 seconds, the measurement platform carrier system finishes transmitting, and the power amplifier enters a standby state. Thereafter, the receiving sensors of the measurement platform subsystem may wait to receive and record echo and retransmitted signals under quiet interference background conditions.
At the moment of 3.2 seconds, the target carrier subsystem receives the synchronous pulse delayed for 2 seconds, the power amplifier of the repeater is started, the receiving state is switched to the transmitting and receiving state, and the repeating signal with fixed strength is continuously transmitted.
And at the moment of 4.3 seconds, after the forwarding is finished, closing the power amplifier of the repeater, and switching the repeater to a receiving and recording state.
At the time of 5.4 seconds, the measurement cycle ends and the next measurement cycle begins.
Step 103) after all the predetermined samples are sampled, the subsequent data processing is carried out. The working situation of the system in the data processing stage is shown in fig. 2, which is a schematic block diagram of the data processing state of the target echo intensity measuring system with fixed forwarding intensity. The method comprises the following specific steps:
1. the subsequent data processing unit obtains the measurement data of a measurement sample from the recording unit of the main measurement platform, and calculates the effective value U of the electric signal for extracting the echoeAnd for forwarding signalsEffective value of electrical signal Ua。
2. The subsequent data processing unit obtains the measured data of a measured sample from the recording unit of the target platform, and calculates and extracts the effective value U of the electric signal of the incident wavei。
3. The target echo intensity of the measurement sample is calculated according to the formula (13) in the specification, wherein SLaIs the fixed signal forwarding strength of the transponder, MaIs the sensitivity of the receiving sensor on the transponder.
4. And repeating 1-3 to complete the calculation processing of all the measurement samples and obtain the target echo intensities of the multiple measurement samples.
5. And performing necessary accepting and weighting processing on the processing results of all samples according to a set rule to obtain a final target intensity measuring result, and performing necessary output and storage on the processing results.
Based on the method, the invention also provides a system for obtaining the target intensity of the target to be detected, and the system comprises:
the system consists of a main measuring platform subsystem, a target platform subsystem to be measured and a data processing subsystem. The data processing subsystem does not participate in measurement data acquisition, and is only used for comprehensively processing the measurement data and giving a measurement result. The first two subsystems, which constitute the measurement working system, are used for realizing measurement data acquisition, and the structural block diagram of the measurement working system is shown in fig. 1.
The main measurement platform subsystem mainly comprises: the device comprises a control unit, a programmable signal generating unit, a synchronizing unit, a collecting and recording unit, a power amplifier unit, a transmitting transducer, a receiving sensor and the like. The programmable signal generating unit is used for generating a transmitting signal waveform; the synchronization unit is used for realizing the synchronous work of the two subsystems of the system; the receiving sensor is used for receiving echo signals of a target and forwarding signals of the forwarding transducer and transmitting electric signals to the data acquisition and recording unit; the acquisition and recording unit converts the electric signals into digital signals and stores the digital signals on a corresponding storage medium (such as a magnetic tape or a hard disk) for subsequent data processing.
And the target platform subsystem to be tested is arranged on the target to be tested. The device comprises a control unit, an echo transponder, a synchronization unit, a data acquisition and recording unit and the like. The echo transponder consists of a receiving sensor, a transmitting transducer and a power amplifier. And the sensor in the echo transponder receives an incident signal which is transmitted by the main transmitting transducer and comes from a transmission channel, and transmits the electric signal to the data acquisition and recording unit. And the acquisition and recording unit is used for converting the electric signals into digital signals and storing the digital signals on a corresponding storage medium for subsequent data processing. According to the frequency band and the signal type of the incident signal, the target load control unit can select and output a forwarding signal with fixed strength through the signal generation unit, and the forwarding signal is amplified through a power amplifier and then excites a forwarding transducer in the echo transponder, so that the forwarding of the incident signal is completed. Wherein, the receiving sensor and the transmitting transducer of the echo transponder are required to be arranged on a target shell which can be directly radiated by an incident signal, and other parts are not required.
The two subsystems of the system are both provided with a synchronization unit, and the two synchronization units can perform remote synchronization by taking a GPS as a reference. Synchronization can also be maintained by using a high precision internal clock source without the measurement of an attached GPS antenna. The design ensures that each subsystem of the whole measuring system is under strict time synchronization control. The echo signal and the retransmission signal of the target can be clearly distinguished from each other in the time domain, so that the necessary hardware platform condition is provided for the measurement method provided by the invention.
After the measurement data acquisition is completed, the data processing subsystem is used to perform data processing according to the steps and the calculation formula given in the technical specification, so as to obtain the final target intensity measurement result, and perform necessary output and storage on the processing result. The working situation of the system in the data processing stage is shown in fig. 2, which is a schematic block diagram of the data processing state of the target echo intensity measuring system with fixed forwarding intensity.
The acquisition recording unit converts the electric signals into digital signals and stores the digital signals on a corresponding storage medium (such as a magnetic tape or a hard disk) for subsequent data processing. The device comprises an analog-digital conversion module, a data transmission module and a storage module. The analog-digital conversion module is used for converting an analog electric signal from the sensor into a digital signal; the data transmission module is used for transmitting data between the analog-to-digital conversion module and the storage module and between the storage module and the subsequent processing unit.
The repeater further includes:
the echo transponder consists of a receiving sensor, a transmitting transducer and a power amplifier.
And the sensor in the echo transponder is used for receiving an incident signal which is transmitted by the main transmitting transducer and comes from a transmission channel and transmitting the electric signal to the data acquisition and recording unit.
The power amplifier receives the signal excitation from the signal generating unit, and the transmitting transducer transmits the forwarding signal with fixed strength after power amplification.
According to the measuring principle of the invention, the receiving transducer and the transmitting transducer of the echo transponder are required to be arranged on a target shell capable of being directly radiated by an incident signal, and the arrangement positions of other parts are not required.
Finally, it should be noted that the examples described herein are only for explaining the present invention, and the present invention is not limited to specific service classes, user terminal classes and payment system classes, and the changes made to the above contents also fall within the protection scope of the present invention.
Claims (4)
1. A target echo intensity measurement method based on fixed forwarding intensity can be used as prior information for further obtaining the distance, the direction and the size of a target to be measured, and the method comprises the following steps:
step 101) obtaining measurement samples of each period according to a certain set period, wherein each measurement sample comprises three parts of data: echo data recorded by the main measuring platform subsystem, incident signal data stored by the measuring platform subsystem of the target to be measured and forwarded signal data;
step 102) sampling the obtained measurement sample, and then performing subsequent data processing to obtain target intensity, wherein the subsequent data processing specifically comprises the following steps:
step 102-1) acquiring the electric signal amplitude U of the echo according to the measurement sample dataeAmplitude U of electric signal of forwarding signalaAnd the amplitude U of the electrical signal of the incident waveiThe method comprises the following specific steps:
according to echo data recorded by a main measuring platform in a measuring sample, calculating an electric signal effective value U corresponding to an echo by adopting the following formulae，
Wherein, TeFor the time length of the echo signal pulse, peInstantaneous amplitude of the echo signal recorded for the main measurement platform in volts;
calculating an electric signal effective value U corresponding to a forwarding signal by adopting the following formula according to the forwarding signal data recorded by a main measuring platform in a measuring samplea，
Wherein, TaFor the duration of the signal pulse, paInstantaneous amplitude of the forwarded signal, in volts, recorded for the primary measurement platform;
according to incident wave data recorded by a target-borne measuring platform in a measuring sample, calculating an electric signal effective value U corresponding to the incident wave at the target by adopting the following formulai，
Wherein, TiFor the time length of the incident signal pulse, piInstantaneous amplitude of the incident wave signal recorded for the target borne measurement platform, in volts, and said piAcquiring a value by additionally arranging acquisition and recording equipment on a measured target;
step 102-2) calculating the target echo intensity TS of a certain measurement sample according to the values of the parameters obtained in the previous step and the following formula, wherein SLaIs a fixed signal forwarding strength, MaSensitivity of the receiving sensor on the object to be measured:
step 102-3) repeating the two steps to complete the calculation processing of all the measurement samples to obtain the target echo intensities TS corresponding to all the measurement samples; and performing accepting and weighting processing on all target echo intensities TS to obtain a final target intensity result.
2. The method according to claim 1, wherein the step 101) specifically comprises: in a measurement period, the transducer of the main measurement platform transmits a measurement signal to a target to be measured; the measuring signal is transmitted to the target to be measured, then a part of signal energy is reflected by the target to be measured, and meanwhile, the equipment on the target to be measured collects and records the waveform p of the incident signali；
After a certain fixed time delay, the target forwards a signal to the main measurement platform through the repeater; the main measuring platform receives the echo signal p of the targeteAnd delayed forwarded signal paAnd storing the signal waveform.
3. The method for measuring the strength of the target echo based on the fixed forward strength as claimed in claim 2, wherein when the measurement period is 4 seconds, the step 101) comprises the following sub-steps:
at the zero second, the synchronous pulse arrives, and the main measuring platform transducer transmits a measuring signal to the target to be measured;
at the first second moment, the main measuring platform transducer finishes transmitting, and a measuring platform subsystem positioned on a target to be measured receives a signal transmitted by the main measuring platform through signal wireless transmission and records the signal;
at the second moment, a transponder contained in a measurement platform subsystem positioned on the target to be measured continuously transmits a forwarding signal with fixed strength to a main measurement platform transducer;
at the third second moment, after the forwarding is finished, closing the power amplifier of the repeater, and switching the repeater to a receiving and recording state;
at the fourth second, the present measurement cycle ends and the next measurement cycle begins.
4. The method according to claim 1, wherein the step 101) is preceded by the steps of: and a step for synchronizing the main measuring platform and the measuring platform subsystem of the object to be measured by using the synchronous source.
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| Fish target strengths for use in echo integrator surveys;Kenneth G. Foote;《Acoustical Society of America》;19870525;第82卷(第3期);981-987 * |
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