KR101881404B1 - receiving apparatus based on correlation width for underwater acoustic communication system with differential phase shift keying and receiving method thereof - Google Patents

Abstract

In order to improve the restoration accuracy of a symbol, the present invention is characterized in that a modulation signal in which a symbol corresponding to one bit data is diffused and transmitted according to a predetermined pseudo noise code is received, and a phase difference between a pair of consecutive symbols A receiver processor for receiving and filtering the modulated signal and transmitting a filtered signal; and a receiver for receiving the modulated signal and restoring the bit data corresponding to the received signal. A delay unit for delaying the filtered signal by a period corresponding to one symbol to transmit a delayed signal; A first correlator for generating a first output signal by mixing a target symbol of the filtered signal and a reference symbol of the delayed signal corresponding to a pair of consecutive symbols of the modulated signal; A second correlator for generating a second output signal by mixing the inverse symbol of which the waveform of the object symbol is inverted and the reference symbol; And extracting an output position of the main pick from a width between the first output signal and the second output signal and comparing the first output signal and the second output signal based on the extracted output value of the main pick, And a decision unit which decodes the bit data of the object symbol and restores the bit data of the object symbol.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correlation-based receiving apparatus and a receiving method for a differential phase modulation type underwater acoustic communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correlation-based receiver and a receiving method in a differential phase modulation type underwater acoustic communication system, and more particularly to a correlation-based receiver and a receiver in a differential phase modulation type underwater acoustic communication system, Receiving method.

Generally, in water, acoustic signals are widely used in place of light or electromagnetic waves whose transmission distance is short because the transmission distance is short in transmitting and receiving signals for communication or detection purposes.

Such underwater acoustic communication using acoustic signals has become a necessary technique of marine research according to the activation of marine development, and it is also known as a sonobuoy that drifts a target area and transmits detection results of an observation object such as a submarine to a base station Applications to marine surveillance systems are expanding.

On the other hand, sound waves in the water are refracted due to different temperature and salinity distributions depending on the area / depth of water, and are influenced by reflection / scattering due to sea level and seabed surface, Doppler effect due to transceiver movement, and other noise sources.

Especially, in an environment with shallow water depths and a complex sea bottom surface, there is a possibility of distortion of the sound signal, so a transmission / reception technology capable of accurately transmitting data of a sound signal is required.

Recently, in the field of underwater acoustic communication, in order to replace phase shift keying (PSK), which requires a synchronous detection process in demodulation, information is transmitted only by carrier phase difference between consecutive symbols, There is an increasing interest in differential phase shift keying (DPSK) that performs demodulation.

Here, DPSK is a modulation scheme in which a phase of a carrier corresponding to digital signal 1 follows a carrier phase previously transmitted, and a carrier phase corresponding to 0 is a phase of inverting a carrier phase previously transmitted by 180 degrees.

Accordingly, it is possible to demodulate the subsequent transmitted signal based on the signal received before the first interval, thereby simplifying the circuit structure of the receiver.

Meanwhile, the conventional DPSK receiver extracts and compares the maximum value among the correlation output values calculated from a pair of consecutive symbols to discriminate the phase difference between consecutive symbols.

Accordingly, in a channel in which a signal-to-noise ratio in which the size of a side pick becomes larger or a channel in which a Doppler shift frequency is higher than a size of a main pick which indicates the similarity of symbol-to-symbol waveforms in the output signal of the correlation output value, .

Korean Patent No. 10-0155519

In order to solve the above problems, it is an object of the present invention to provide a correlation-based receiver and a reception method of a differential phase modulation type underwater acoustic communication system in which restoration accuracy of a symbol is improved.

According to an aspect of the present invention, there is provided an apparatus for receiving a modulated signal in which a symbol corresponding to one bit data is spread according to a predetermined pseudo noise code and transmitted, A correlation-based receiver of a differential phase modulation type underwater acoustic communication system for recovering bit data corresponding to each symbol through a pair of consecutive symbols of a signal, the correlation-based receiver comprising: receiving and filtering the modulated signal, A reception processing unit for transmitting the transmission signal; A delay unit for delaying the filtered signal by a period corresponding to one symbol to transmit a delayed signal; A first correlator for generating a first output signal by mixing a target symbol of the filtered signal and a reference symbol of the delayed signal corresponding to a pair of consecutive symbols of the modulated signal; A second correlator for generating a second output signal by mixing the inverse symbol of which the waveform of the object symbol is inverted and the reference symbol; And extracting an output position of the main pick from a width between the first output signal and the second output signal and comparing the first output signal and the second output signal based on the extracted output value of the main pick, And a decision unit which decodes the bit data of the object symbol and restores the bit data of the object symbol.

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According to another aspect of the present invention, there is provided an apparatus for receiving a modulated signal in which a symbol corresponding to one bit data is spread according to a predetermined pseudo noise code and transmitted, The method includes receiving a filtered signal, filtering the received signal, and outputting a filtered signal, wherein the filtered signal is delayed at a period corresponding to one symbol to generate a delayed signal, A first step of sending out the first signal; A target symbol of the filtered signal corresponding to a pair of consecutive symbols of the modulated signal and a reference symbol of the delayed signal are mixed to generate a first output signal, and the inverse symbol of which the waveform of the target symbol is inverted, A second step of generating a second output signal by mixing the first output signal and the second output signal; And a third step in which the main output values of the first output signal and the second output signal are compared with each other and the bit data of the target symbol is recovered according to the height of the main peak output value, A correlation-based reception method of a communication system is provided.

Through the above solution, the present invention provides the following effects.

First, an output position of a main pick is extracted from a width between the first output signal and a side point of the second output signal, and the first output signal and the second output signal are outputted on the basis of the extracted output value of the main pick. The output position of the main picture is detected according to the width of the side pits of the determination unit for restoring the bit data of the target symbol. When the output signals of the main picture are compared with each other based on the detected output value of the main picture, The error due to an increase in the output value of the side pick is minimized, thereby improving the accuracy of the signal restoration.

Secondly, a side pick is set through a process of selecting one of the peaks in the output signal and determining whether it has an interval corresponding to twice the spreading factor, and the output position of the main pick is extracted as a median output position between the set side fingers The output value of the main pick can be detected quickly / accurately from each output signal, so that continuous real-time signal restoration is possible, and more accurate signal restoration can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a correlation width based receiver of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention; FIG.
2 is a circuit diagram illustrating a first correlation unit and a second correlation unit in a correlation width based receiver of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention;
3 is a diagram illustrating a signal input process for a first correlation unit and a second correlation unit in a correlation width based receiver of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention.
4 is a block diagram showing a determination unit in a correlation-width-based reception apparatus of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention.
5A, 5B, and 5C are examples of output signals in a correlation width based receiver of a differential phase modulation underwater acoustic communication system, in accordance with an embodiment of the present invention.
6 is a flowchart illustrating a correlation width based receiving method of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

FIG. 1 is a block diagram illustrating a correlation-based receiver of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention. FIG. 2 is a block diagram of a differential phase modulation type underwater acoustic communication system FIG. 3 is a circuit diagram illustrating a first correlation unit and a second correlation unit in a correlation-width-based reception apparatus according to an embodiment of the present invention. FIG. And FIG. 4 is a block diagram illustrating a determination unit in a correlation-width-based reception apparatus of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention. 5a, 5b and 5c are diagrams illustrating output signals in a correlation-based receiver of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention. The.

1 to 5C, the correlation-based reception apparatus 100 of the differential phase modulation type underwater acoustic communication system according to the preferred embodiment of the present invention includes a reception processing unit 10, a delay unit 20, A correlation unit 30a, a second correlation unit 30b, and a decision unit 40. [

The correlation width based receiving apparatus 100 refers to a receiver that receives a modulated signal bs modulated by differential phase modulation (DPSK) and restores bit data transmitted through the modulated signal bs do.

At this time, the modulation signal bs is modulated by a direct sequence spread spectrum scheme in which symbols corresponding to one bit data are spread by a pseudo random noise sequence. desirable.

 On the other hand, in the differential phase modulation system, the transmitting apparatus differential-codes and transmits bit data through an exclusive OR (XOR) operation.

That is, the same bit data as the reference bit data is transmitted as a symbol having a waveform having the same phase as the waveform of the previously transmitted symbol, and the bit data other than the reference bit data is transmitted to the waveform of the previously transmitted symbol, ≪ / RTI >

For example, when the reference bit data is 1 and the subsequent bit data after the symbol of the first waveform corresponding to the reference bit data is 1, the symbol of the first waveform is transmitted, and when 0, the symbol of the second waveform is transmitted.

If the subsequent bit data is 1 after the symbol of the second waveform, the symbol of the second waveform is transmitted, and if it is 0, the symbol of the first waveform is transmitted.

At this time, the correlation-based receiver 100 can recover bit data corresponding to each symbol through a pair of consecutive symbols of the modulation signal.

 That is, the waveform of the subsequently received symbol is compared with the waveform of the previously received symbol to restore bit data identical to the reference bit data when the two waveforms are similar, and to recover the bit data different from the reference bit data when the two waveforms are different have.

For example, when the reference bit data is 1 and the symbol corresponding to the reference bit data is the first waveform, 1 is recovered when the symbol of the first waveform is received after the symbol of the first waveform corresponding to the reference bit data, When a symbol of two waveforms is received, 0 is restored.

When the waveform of the next received symbol is the second waveform after the symbol of the second waveform, the bit data of 1 is restored and the bit data of 0 is restored when the first waveform is the first waveform.

The reception processing unit 10 receives and filters the modulated signal bs and transmits the filtered signal fs and outputs the filtered signal fs to the antenna 10 through a band pass filter (BPF), a Doppler estimator, a down converter, a low pass filter (LPF) A regenerator, and the like.

At this time, a modulated signal transmitted from the transmitting apparatus through the antenna can be received, unnecessary frequency and signal distortion are removed in the modulated signal received through the BPF, the Doppler estimator, the down converter, the LPF, A filtering process for converting the frequency to a frequency suitable for demodulation can be performed.

The filtering signal fs includes a first correlation unit 30a, a second correlation unit 30b, a delay unit 20, and a second correlation unit 30b. .

The delay unit 20 may include a delay circuit or the like and delays the filtering signal fs at a cycle corresponding to one symbol to transmit the delay signal ds.

That is, the delay signal ds is a filtering signal fs delayed by a period corresponding to one symbol corresponding to one bit data of the filtering signal fs.

At this time, the delay signal ds is sent to the first correlation unit 30a and the second correlation unit 30b.

2 to 3, the first correlator 30a receives the target symbol b1 of the filtering signal fs corresponding to a pair of consecutive symbols of the modulation signal bs, And mixes the reference symbol b2 of the signal ds to generate the first output signal cs1.

In detail, the filtering signal fs and the delay signal ds are comprised of a plurality of symbols having the same arrangement, and the delay signal ds is delayed by a period corresponding to one symbol via the delay unit 20 And transmitted to the first correlation unit 30a.

Accordingly, when the target symbol b1 to be restored in the filtering signal fs is input to the first correlation unit 30a, the reference symbol b1 of the delay signal ds input at the same time as the target symbol b1, (b2) has the same waveform as the symbol before the period corresponding to one symbol from the object symbol (b1) in the filtering signal (fs).

In other words, a pair of consecutive symbols in the modulation signal bs, that is, a symbol to be restored and a restoration-based symbol may be simultaneously input to the first correlation unit 30a.

The first correlation unit 30a may include a multiplier 31 and an integrator 32. The first correlation unit 30a may multiply the input symbol b1 and the reference symbol b2 by a multiplier 31 and an integrator 32 ) To generate a first output signal cs1 indicating the similarity between signals, that is, a correlation measure.

When the target symbol b1 and the reference symbol b2 have the same waveform, a correlation output signal is generated with a high output value of the main pixel p3 as shown in FIG. 5A. If the waveform of the opposite phase of the symbol b2 is present, the correlation output signal can be generated with a low output value of the main pixel P8 as shown in FIG. 5B.

The second correlator 30b generates a second output signal cs2 by mixing the inverse symbol of which the waveform of the object symbol b1 is inverted and the reference symbol b2.

Here, the inverse symbol is a symbol having a phase difference of 180 degrees with respect to the object symbol b1, the symbol having a waveform inverted from the symbol to be restored, and the symbol Can be input simultaneously.

The second correlation unit 30b may include a multiplier and an integrator. The second correlation unit 30b may generate the second output signal cs2 by operating the input inverse symbol and the reference symbol b2 through a multiplier and an integrator .

When the inverse symbol and the reference symbol b2 have the same waveform, a correlation output signal is generated in a form in which the output value of the main pixel P3 is high as shown in FIG. 5A, and the target symbol b1 and the reference symbol b2 , The correlation output signal is generated in such a manner that the output value of the main pixel P8 is low as shown in FIG. 5B.

The decision unit 40 compares the first output signal cs1 and the second output signal cs2 to recover the bit data of the object symbol b1.

The decision unit 40 restores the bit data of the object symbol b1 according to whether the waveform of the object symbol b1 is equal to the waveform of the reference symbol b2, the first output signal cs1 and the second output signal cs2 are compared to determine the identity between the waveforms of the first output signal c2 and the second output signal c2.

If it is determined that the waveform of the object symbol b1 and the waveform of the reference symbol b2 are identical according to the comparison result of the output signals cs1 and cs2, the bit data of the object symbol b1 is equal to the reference bit data And if the two waveforms are determined to be different, the bit data of the object symbol b1 is restored to the bit data different from the reference bit data.

In particular, when the object symbol b1 and the reference symbol b2 have the same waveform, the inverse symbol and the reference symbol b2 have a waveform of an opposite phase, and the object symbol b1 and the reference symbol b2, the inverse symbol and the reference symbol b2 have the same waveform when the symbol b2 has a waveform of the opposite phase.

For example, if the target symbol b1 has the first waveform, the inverse symbol has the second waveform that is 180 degrees out of phase with the first waveform, and the inverse symbol has the second waveform when the target symbol b1 has the second waveform. And a first waveform having a phase difference of 180 degrees.

At this time, the determination unit 40 may include a determination circuit. The determination unit 40 extracts a predetermined representative value for each of the first output signal cs1 and the second output signal cs2, The similarity between the waveforms of the target symbol b1 and the reference symbol b2 can be determined.

That is, when one output signal is compared with a predetermined reference value as in the prior art, the output value of the output signal fluctuates when distortion such as a change in the amplitude of the symbol occurs due to the influence of the channel, And the error probability for judging the similarity of waveforms between symbols is increased.

In the present invention, the first output signal cs1 and the second output signal cs2 indicating the correlation measure of the target symbol b1 and the reference symbol b2, the inverse symbol and the reference symbol b2, respectively, The first output signal cs1 and the second output signal cs2 are compared with each other so that the output value intensity of the output signal becomes larger or smaller due to signal distortion The waveform similarity between the symbols can be accurately determined.

The determination unit 40 extracts the output position of the main pick from the width of the side pels of the output signals cs1 and cs2 and outputs the first output signal cs1 And the second output signal cs2 to determine the waveform similarity between the object symbol b1 and the reference symbol b2.

Here, it is preferable to understand that the term "width between side pits" means a difference in output position of each side pick in the output signal.

That is, the determination unit 40 detects a pair of side peaks from the first output signal cs1 and extracts an output value corresponding to the main peak as a representative value through an output position difference between the detected two side pixels .

The determination unit 40 detects a pair of side-peaks from the second output signal cs2 and extracts an output value corresponding to the main-picture as a representative value through an output position difference between the detected two side-peaks .

At this time, the decision unit 40 determines the symbols b1 and b2 according to the result of the comparison of the representative value extracted from the first output signal cs1 and the representative value extracted from the second output signal cs2, It is possible to determine the waveform similarity between the reference symbols b2.

The output value of the main peak indicates a correlation measure between the symbols input to the correlation units 30a and 30b. The larger the output value of the main peak, the higher the waveform similarity between the input symbols becomes. As the output value of the main peak decreases, Which means that the similarity of the liver waveform is low.

In detail, the determination unit 40 may include a side-peak detecting unit 41 and a main-pick detecting unit 42.

Here, the side pick detector 41 detects a pair of base peaks having a predetermined threshold value or more from the respective output signals cs1 and cs2, and detects a pair having a gap corresponding to a predetermined reference interval among the detected base peaks And sets it as a side pick.

In this case, the threshold value is preferably set in consideration of the amplitude, signal-to-noise ratio, and the like of the target symbol b1 related to the output value intensity of the output signal.

In detail, the side-peak detecting unit 41 can classify output signals generated through the correlating units 30a and 30b by sample units and recognize them as individual peaks.

That is, the sample means a division unit corresponding to one bit in the output signal, and the side-peak detecting unit 41 can recognize one pick for one bit.

Then, a plurality of individual peaks of the output signal having an output value equal to or greater than a predetermined threshold are extracted, and the extracted peaks are set as base peaks and stored in registers.

At this time, information on the output position of each base pick is stored in the register. Here, the term "output position" is understood to mean the order of each pick according to the sample unit on the output signal or the time during which the corresponding pick is output in the entire output signal.

For example, referring to FIG. 5A, when the threshold is set to 5, five of the output signals P1, P2, P3, P4, and P5 may be stored in the register.

Then, one of the stored base peaks P1, P2, P3, P4, and P5 is selected and the remaining interval is calculated from the selected one. In this case, it is preferable to understand that the calculated interval means a difference in order of samples among the peaks to be compared on the output signal or a time difference outputted to the output signal.

Herein, the calculated interval is compared with a reference interval, and a pair of base picks P1 and P5 corresponding to the reference interval is set as the side pick.

Of course, if there is no interval corresponding to the reference interval among the intervals calculated for the remaining base picks from the selected one base pick, the other base picks are selected and the interval for the remaining base picks is calculated and compared with the reference interval Is repeated.

Here, the reference interval may be set to correspond to twice the spreading factor of the pseudo noise code.

In this case, the spreading factor means the number of bit strings of the pseudo noise code, and the reference interval can be set to a sample unit corresponding to twice as many as the bit string number of the spreading factor.

For example, when the spreading factor is 16, one symbol is spread by a pseudo noise code having 16 bit strings, and an output signal according to the multiplication and integration operation between the first symbol and the second symbol is 64 Are output in units of samples corresponding to bits.

In this case, the output signal includes a pair of side peaks indicating the integration result for each of the first symbol and the second symbol, being spaced apart in units of samples corresponding to 32 bits, and the summed integration result of the first symbol and the second symbol Are arranged at the center portions of the pair of side picks.

Here, the reference interval is set to a unit of a sample corresponding to 32 bits that is twice the spreading factor. When the interval of a selected pair of detected base peaks is spaced by a sample unit corresponding to 32 bits, The pick can be set as a side pick.

As described above, a process of setting a side pick for extracting the output position of the main pick may be performed quickly and accurately by selecting one of the peaks in the output signal and determining whether the pair has a gap corresponding to twice the spreading factor.

The main pick detecting unit 42 receives the output positions L1 and L2 of the set side picks P1 and P5 from the side pick detecting unit 41 and detects the position between the pair of side picks P1 and P5 And extracts the output position of the main pick P3 according to the output position median.

For example, when the output position of one side pick (P1) is 16th with respect to the sample unit and the output position of the other side pick (P5) is 48th with respect to the sample unit, Can be extracted to the output position of the main pick P3.

At this time, the side pick detector 41 and the main pick detector 42 perform the same process for the first output signal cs1 and the second output signal cs1, It is possible to extract the pick output position and the main pick output position of the second output signal cs2.

For example, referring to FIG. 5B, when the threshold is set to 5, two of the output signals P6 and P7 may be stored in the register.

Then, one of the stored base pits P6 and P7 is selected, and the remaining interval is calculated from the selected one. Herein, the calculated interval is compared with a reference interval, and a pair of base picks P6 and P7 corresponding to the reference interval is set as the side pick.

The main pick detecting unit 42 receives the output positions L3 and L4 of the set side picks P6 and P7 from the side pick detecting unit 41 and receives the output positions L3 and L4 between the pair of side picks P6 and P7 And extracts the output position of the main pick P8 according to the median output position.

In this manner, a pair of the peaks in the output signal is selected to set a side-pick having an interval corresponding to twice the spreading factor, and the output position of the main-pick is extracted with the median value of the output positions of the side- So that it is possible to perform continuous and real-time signal restoration while achieving more accurate signal restoration.

The detecting unit 40 may further include a correlation determining unit 43 for detecting output values corresponding to the main-peak output positions from the output signals cs1 and cs2 and comparing the output values.

The correlation determining unit 43 compares the first output value corresponding to the main output of the first output signal cs1 and the second output value corresponding to the main output of the second output signal cs2.

If the first output value exceeds the second output value, the correlation determining unit 43 restores the same bit data as the reference bit data, and if the first output value is less than the second output value, Restore.

That is, the correlation determining section 43 determines that the first output value indicating the degree of correlation with respect to the target symbol b1 and the reference symbol b2 is greater than the second output value indicating the degree of correlation with respect to the inverse symbol and the reference symbol b2 , It is determined that the waveform of the target symbol b1 and the waveform of the reference symbol b2 are similar.

If the second output value is larger than the first output value, it can be determined that the waveform of the target symbol b1 and the waveform of the reference symbol b2 are different.

Here, the reference bit data may be set to one of 1 or 0 as a reference bit in the differential phase modulation and demodulation process.

For example, when the reference bit data is set to 1 as shown in FIG. 5A, the first output signal cs1 has a high output value of the main pick and the second output signal cs2 has the output value of the main- Since the first output value is lower than the second output value, the correlation determining unit 43 restores 1 as bit data for the object symbol b1.

5B, the first output signal cs1 has a low output value of the main pick and the second output signal cs2 has a high output value of the main peak as shown in FIG. 5A, The second output value is larger than the first output value, the correlation determining unit 43 restores 0 as bit data for the object symbol b1.

Accordingly, accurate signal restoration can be performed even when the signal-to-noise ratio is low or the symbol passing through the channel having a high Doppler shift frequency is distorted as shown in FIG. 5C and the output value of the side picks P9 and P11 becomes high.

That is, unlike the conventional method of comparing the maximum value of the output signals cs1 and cs2 to determine the waveform similarity between the target symbol b1 and the reference symbol b2, And the main peak output values are compared with each other, the error due to an increase in the output value of the side peak is minimized in the distortion of the symbol due to the influence of the channel, Can be improved.

FIG. 6 is a flowchart illustrating a correlation-based reception method of a differential phase modulation type underwater acoustic communication system according to an embodiment of the present invention.

As shown in FIG. 6, the correlation-based receiving method of the differential phase modulation type underwater acoustic communication system can be performed as follows.

First, the modulated signal bs that has passed through the channel is received and filtered, the filtered signal fs is transmitted, and the filtered signal fs is delayed at a period corresponding to one symbol to transmit the delayed signal ds (s10).

That is, when the modulation signal bs is received through the antenna of the reception processing unit 10, the received modulation signal bs is transmitted through the BPF, the Doppler estimator, the down converter, the LPF, Filtered and output as the filtering signal fs.

The filtering signal fs is sent to the first correlating unit 30a and the second correlating unit 30b and the delay unit 20 and the filtered signal fs sent to the delay unit 20 is delayed Signal ds and transmitted to the first correlation unit 30a and the second correlation unit 30b.

The target symbol b1 of the filtered signal fs corresponding to a pair of consecutive symbols of the modulated signal bs and the reference symbol b2 of the delayed signal ds are transmitted through the first correlator 30a, Are mixed to generate a first output signal cs1 (s20).

At the same time, the second output signal cs2 is generated by mixing the inverse symbol and the reference symbol b2 in which the waveform of the object symbol b1 is inverted through the second correlation unit 30a (s20).

Here, the first output signal cs1 and the second output signal cs2 represent a waveform similarity measure between symbols input to the correlating units 30a and 30b, and the generated first output signals cs1 and The second output signal (cs2) is input to the determination unit (40).

A peak of a predetermined threshold or more is detected from the first output signal cs1 through the side-pick detecting unit 41 of the determining unit 40, and an interval corresponding to a predetermined reference interval among the detected peaks Is set as a side pick.

At this time, the main pick detection unit 42 of the determination unit 40 extracts the output position of the main pick according to the median output position position between the set pair of side finges.

When the output position of the main pick for the first output signal cs1 is extracted, the output position of the main pick is extracted through the same process for the second output signal cs2, And is input to the correlation determination unit 43 of the determination unit 40. [

At this time, the correlation determining unit 43 detects an output value corresponding to the main-picture output position from each output signal cs1, and the first output signal cs1 and the second output signal cs2 are based on the detected output value And the bit data of the target symbol b1 is restored according to the height of the main peak output value (s30).

Meanwhile, the correlation-based receiver of the differential phase modulation type underwater acoustic communication system may be provided as one correlation unit.

The correlation unit mixes the target symbol of the filtered signal and the reference symbol of the delayed signal to generate an output signal. The determination unit compares the output value corresponding to the main peak of the output signal with a preset reference value, Can be restored.

Here, the determination unit may detect an output position for a pair of side picks from one output signal, and may detect a position of the main pick by a median output position between the pair of side picks.

The determining unit may detect the output value from the output signal so as to correspond to the position of the detected main pick, and may compare the detected output value with a preset reference value.

At this time, when the output value is larger than a preset reference value, the determining unit determines that the waveform of the reference symbol and the reference symbol are similar, and can restore the same bit data as the reference bit data with the bit data of the target symbol.

The determining unit may determine that the waveform of the reference symbol and the reference symbol are different when the output value is smaller than a preset reference value, and recover bit data different from the reference bit data by bit data of the target symbol.

Thus, the waveform similarity of the target symbol and the reference symbol can be accurately discriminated based on the output value of the main pick, and the circuit structure of the receiving apparatus can be further simplified.

As described above, the present invention is not limited to the above-described embodiments, and variations and modifications may be made by those skilled in the art without departing from the scope of the present invention. And such modifications are within the scope of the present invention.

100: Correlation-width-based receiving apparatus 10: Reception processing unit
20: delay unit 30a: first correlation unit
30b: second correlation unit 40:

Claims (7)

A method of receiving a modulated signal in which a symbol corresponding to one bit data is spread according to a predetermined pseudo noise code and is transmitted and restores bit data corresponding to each symbol through a successive pair of symbol phase differences of the modulated signal A correlation width based receiver of a differential phase modulation type underwater acoustic communication system,
A reception processor for receiving and filtering the modulated signal and transmitting a filtered signal;
A delay unit for delaying the filtered signal by a period corresponding to one symbol to transmit a delayed signal;
A first correlator for generating a first output signal by mixing a target symbol of the filtered signal and a reference symbol of the delayed signal corresponding to a pair of consecutive symbols of the modulated signal;
A second correlator for generating a second output signal by mixing the inverse symbol of which the waveform of the object symbol is inverted and the reference symbol; And
Extracting an output position of the main pick from a width between the first output signal and the side pick of the second output signal and comparing the first output signal and the second output signal based on the extracted output value of the main pick And a decision unit for restoring the bit data of the object symbol. The method according to claim 1,
The determination unit
A pair of base peaks having a predetermined threshold or more from the first output signal and the second output signal and having a gap corresponding to a preset reference interval among the detected base peaks, A pick detector,
And a main pick detector for extracting an output position of the main pick according to a median output position position between the set pair of side pips from the first output signal and the second output signal. Correlation-based receiver of a system. 3. The method of claim 2,
Wherein the reference interval is set to correspond to twice the spreading factor of the pseudo noise code. delete A differential phase detector that receives a modulated signal in which a symbol corresponding to one bit data is spread according to a predetermined pseudo noise code and is transmitted and restores bit data corresponding to each symbol through a phase difference between consecutive symbols of the modulated signal, A method for receiving a correlated width in a modulation-type underwater acoustic communication system,
A first step in which the modulated signal is received and filtered to send a filtered signal and the filtered signal is delayed at a period corresponding to one symbol to transmit a delayed signal;
A target symbol of the filtered signal corresponding to a pair of consecutive symbols of the modulated signal and a reference symbol of the delayed signal are mixed to generate a first output signal, and the inverse symbol of which the waveform of the target symbol is inverted, A second step of generating a second output signal by mixing the first output signal and the second output signal; And
And a third step in which the main output values of the first output signal and the second output signal are compared with each other and the bit data of the target symbol is recovered according to the height of the main peak output value, A correlation - based reception method of a system. 6. The method of claim 5,
In the third step,
Detecting at least a predetermined threshold from the first output signal and the second output signal;
A pair of peaks having an interval corresponding to a predetermined reference interval among the detected peaks is extracted and set as a side pick;
And extracting an output position of the main pick according to a median output position position between the pair of side pips from the first output signal and the second output signal. Way. The method according to claim 6,
In the third step,
Wherein the reference interval is set to correspond to twice the spreading factor of the pseudo noise code. ≪ RTI ID = 0.0 > 15. < / RTI >

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