Reception device and reception method

Abstract

This reception device comprises: a reception unit that receives, as a reception signal, a transmission signal transmitted from a transmission device; a matching filter unit that limits the bandwidth of the reception signal to the bandwidth of the transmission signal; and a Doppler shift estimation / correction unit that estimates and corrects the Doppler shift of the reception signal. The matching filter unit is disposed downstream of the Doppler shift estimation / correction unit.

Description

Receiving device and receiving method

[0001] The present invention relates to a receiving device and a receiving method.

[0002] In underwater acoustic communications, communication quality can be degraded by the effects of multipath, Doppler shift, and noise. To prevent this degradation in communication quality, an equalizer is used to compensate for multipath distortion. To address Doppler shift, a Doppler shift correction algorithm is used that uses carrier frequency correction and resampling. A matched filter is used to reduce noise. Underwater acoustic communications devices that implement these functions are known (see Non-Patent Document 1).

[0003] Fig. 8 is a schematic diagram of a conventional underwater acoustic communication system 100. Fig. 9 is a diagram showing an example of the spectrum of a signal used in the conventional underwater acoustic communication system 100. The underwater acoustic communication system 100 includes a transmitting device 10 and a receiving device 20. The transmitting device 10 and the receiving device 20 are installed underwater 50. The transmitting device 10 generates a baseband signal to transmit data to the receiving device 20. The baseband signal generated by the transmitting device 10 has a center frequency of 0 and a bandwidth of f, as shown in Fig. 9 (1), for example. ｗ The transmitting device 10 performs transmission processing such as modulation on the generated baseband signal and transmits it to the receiving device 20. The signal transmitted by the transmitting device 10 has a spectrum represented by the central frequency f ｃ and the bandwidth is f ｗ The spectrum is given by:

[0004] As shown in Fig. 8, a conventional receiving device 20 includes a receiving unit 21, an AD (Analog to Digital) converter unit 22, a downconverter 23, a matched filter unit 26, a Doppler shift estimating and compensating unit 25, and an equalizing unit 27. The receiving unit 21 receives the sound wave A1 transmitted by the transmitting device 10 and outputs it to the AD converter unit 22. The signal received by the receiving device 20 has a center frequency of f, as shown in Fig. 9 (3), for example. ｃ +(v / c)f ｃ and the bandwidth is f ｗIn other words, when the signal transmitted by the transmitting device 10 is received by the receiving device 20, the center frequency is changed to (v / c)f due to the Doppler shift. ｃ [Hz]. Also, the bandwidth is f ｗ (1 + v / c), where c [m / s] is the propagation speed of the transmission medium, and v [m / s] is the relative movement speed between the transmitting device 10 and the receiving device 20.

[0005] The AD converter unit 22 quantizes the signal output by the receiver unit 21 to convert it into a digital signal, and outputs it to the downconverter unit 23. The downconverter unit 23 converts the signal output by the AD converter unit 22 into a baseband signal by performing frequency conversion, and outputs it to the matched filter unit 26. The signal output by the downconverter unit 23 has a center frequency of f ｄ and the bandwidth is f ｗ The spectrum shown in Fig. 9(4) has a center frequency that is shifted and a bandwidth that is wider than the spectrum shown in Fig. 9(1).

[0006] The matched filter unit 26 applies a band f used on the transmitting device 10 side to the signal output from the down-converter unit 23. ｘ The signal output from the matched filter unit 26 has a center frequency of f ｄ and the bandwidth is f ｗ (1+v / c) to a predetermined width f ｌｏｓｓ has a missing spectrum.

[0007] The Doppler shift estimating and compensating unit 25 estimates the Doppler shift of the signal output by the matched filter unit 26, corrects the Doppler shift by performing carrier frequency correction and resampling, and outputs the signal to the equalizing unit 27. The equalizing unit 27 compensates for multipath distortion by performing automatic equalization on the signal output by the Doppler shift estimating and compensating unit 25.

[0008] In the conventional underwater acoustic communication system 100 shown in FIG. ｗ For the suppressed band f ｌｏｓｓ The ratio R ｌｏｓｓ is expressed as the following equation (1).

[0009]

[0010] Fig. 10 is a table showing an example of the characteristics of land mobile radio communication and underwater acoustic communication. The first row of the table shown in Fig. 10 shows an example of parameters for land mobile radio communication assuming communication with a base station from inside a Shinkansen train.

[0011] As shown in the first row of the table in FIG. 10, the propagation speed c [m / s] in land mobile radio communication is 299792458 [m / s], the moving speed v [m / s] of the receiving device is 83.3 [m / s] (i.e., 300 km / h), and the center frequency f ｃ [Hz] is 1500000000 [Hz], and the bandwidth f ｗ When [Hz] is 20,000,000 [Hz], the ratio R of the suppressed band ｌｏｓｓ [%] is 0.002 [%].

[0012] On the other hand, as shown in the second row of the table in FIG. 10, the propagation velocity c [m / s] in underwater acoustic communication is 1500 [m / s], the moving velocity v [m / s] of the receiving device is 10.2 [m / s] (i.e., 20 knots), and the center frequency f ｃ [Hz] is 30000 [Hz], and the bandwidth f ｗ When [Hz] is 1000 [Hz], the ratio R of the suppressed band is ｌｏｓｓ [%] is 20.7[%].

[0013] In other words, in land mobile radio communications, even in a moving environment of 300 km / h, the suppressed bandwidth is only 0.002% of the total. On the other hand, in underwater acoustic communications, the suppressed bandwidth is 20%, which is an order of magnitude larger than that of land radio communications, and the impact on communication quality cannot be ignored.

[0014] M. Stojanovic, JA Catipovic and JG Proakis, "Phase-coherent digital communications for underwater acoustic channels," in IEEE Journal of Oceanic Engineering, vol. 19, no. 1, pp. 100-111, Jan. 1994, doi: 10.1109 / 48.289455.

[0015] As described above, in the case of underwater acoustic communication with a small fractional bandwidth (the value obtained by dividing the bandwidth by the center frequency), with the configuration of a conventional receiving device, some bands of the received signal are suppressed, resulting in a problem of degraded communication quality.

[0016] In view of the above circumstances, an object of the present invention is to provide a technique that can prevent degradation of communication quality due to suppression of some bands of a received signal when performing underwater acoustic communication.

[0017] One aspect of the present invention is a receiving device comprising: a receiving unit that receives a transmission signal transmitted from a transmitting device as a received signal; a matched filter unit that limits the bandwidth of the received signal to the bandwidth of the transmission signal; and a Doppler shift estimation and correction unit that estimates and corrects a Doppler shift for the received signal, wherein the matched filter unit is arranged subsequent to the Doppler shift estimation and correction unit.

[0018] Another aspect of the present invention is a receiving method comprising: a receiving step of receiving a transmission signal transmitted from a transmitting device as a received signal; a matched filter step of limiting the bandwidth of the received signal to the bandwidth of the transmission signal; and a Doppler shift estimation and correction step of estimating and correcting a Doppler shift for the received signal, wherein the matched filter step is performed after the Doppler shift estimation and correction step.

[0019] According to the present invention, when performing underwater acoustic communication, it is possible to prevent degradation of communication quality due to suppression of some bands of the received signal.

[0020] FIG. 1 is a schematic configuration diagram of an underwater acoustic communication system according to a first embodiment of the present invention. FIG. 2 is a sequence diagram showing processing in the underwater acoustic communication system according to the first embodiment of the present invention. FIG. 3 is a diagram showing an example of the spectrum of a signal used in the underwater acoustic communication system according to the first embodiment of the present invention. FIG. 4 is a schematic configuration diagram of an underwater acoustic communication system according to a second embodiment of the present invention. FIG. 5 is a diagram explaining a method of setting a passband to be set in a band-limiting filter unit according to the second embodiment of the present invention. FIG. 6 is a diagram explaining a method of setting a passband to be set in a band-limiting filter unit according to the second embodiment of the present invention. FIG. 7 is a sequence diagram showing processing in the underwater acoustic communication system according to the second embodiment of the present invention. FIG. 8 is a diagram showing an example of the spectrum of a signal used in the underwater acoustic communication system according to the second embodiment of the present invention. FIG. 9 is a schematic configuration diagram of a conventional underwater acoustic communication system. FIG. 10 is a diagram showing an example of the spectrum of a signal used in a conventional underwater acoustic communication system. FIG. 11 is a table showing example characteristics of land mobile radio communication and underwater acoustic communication.

[0021] First and second embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment will be described.

[0022] 1 is a schematic diagram of an underwater acoustic communication system 100a according to a first embodiment of the present invention. The underwater acoustic communication system 100a includes a transmitting device 10a and a receiving device 20a. The transmitting device 10a and the receiving device 20a are installed underwater 50. The transmitting device 10a transmits a sound wave A2 to the receiving device 20a, thereby transmitting data from the transmitting device 10a to the receiving device 20a.

[0023] The receiving device 20a includes a receiving unit 21a, an AD (Analog to Digital) converter unit 22a, a downconverter unit 23a, a Doppler shift estimating and compensating unit 25a, a matched filter unit 26a, an equalizer unit 27a, a control unit 30a, and a storage unit 40a.

[0024] The receiver 21a is connected to the AD converter 22a. The receiver 21a has a sound sensor and detects sound waves transmitted from the transmitter 10a. The AD converter 22a is connected to the receiver 21a and the downconverter 23a. The AD converter 22a quantizes the input analog signal to convert it into a digital signal.

[0025] The downconverter unit 23a is connected to the AD converter unit 22a and the Doppler shift estimating / compensating unit 25a. The downconverter unit 23a converts an input high-frequency signal into a low-frequency baseband signal. The Doppler shift estimating / compensating unit 25a is connected to the downconverter unit 23a and the matched filter unit 26a. The Doppler shift estimating / compensating unit 25a estimates a Doppler shift that occurs when the receiving device 20a receives the sound wave A2 from the transmitting device 10a, and corrects the Doppler shift by performing carrier frequency correction and resampling.

[0026] The matched filter unit 26a is connected to the Doppler shift estimating and compensating unit 25a and the equalizer unit 27a. The matched filter unit 26a extracts signals in the transmission band by limiting the band used by the transmitting device 10a. The equalizer unit 27a is connected to the matched filter unit 26a. The equalizer unit 27a includes an equalizer and compensates for multipath distortion by automatically equalizing the input signal.

[0027] The control unit 30a includes a CPU (Central Processing Unit) and controls each unit of the receiving device 20a. The storage unit 40a includes a memory and stores data necessary to operate the receiving device 20a, data received from the transmitting device 10a, and the like.

[0028] 2 is a sequence diagram showing the processing in the underwater acoustic communication system 100a according to the first embodiment of the present invention. First, the transmitting device 10a generates a baseband signal based on data to be transmitted to the receiving device 20a (step S11 in FIG. 2). The spectrum of the baseband signal generated by the transmitting device 10a in step S11 may have a center frequency of 0 [Hz] and a bandwidth of f, as shown in FIG. 3(1). ｗ The spectrum is in Hz.

[0029] Next, the transmitting device 10a performs transmission processing such as modulation and encoding on the baseband signal generated in step S11 to generate a transmission signal, and transmits the transmission signal as a sound wave to the receiving device 20a (step S12 in FIG. 2). Note that, due to the transmission processing, the spectrum of the transmission signal transmitted by the transmitting device 10a in step S12 may be, for example, a spectrum having a center frequency of f ｃ [Hz], and the bandwidth is f ｗ The spectrum is in Hz.

[0030] The receiving section 21a of the receiving device 20a receives the transmission signal transmitted by the transmitting device 10a in step S12 (step S13 in FIG. 2), and outputs the received signal to the AD converter section 22a.

[0031] Next, the AD converter unit 22a of the receiving device 20a quantizes the signal output from the receiving unit 21a in step S13, converting it from an analog signal to a digital signal (step S14 in FIG. 2), and outputs it to the downconverter unit 23a. Note that the spectrum of the signal output from the AD converter unit 22a in step S14 may be different from that of the signal having a center frequency of f as shown in (3) in FIG. 3 due to the Doppler shift that occurs between the transmitting device 10a and the receiving device 20a. ｃ +(v / c)f ｃ [Hz], and the bandwidth is f ｗ The spectrum is (1+v / c) [Hz].

[0032] Next, the downconverter unit 23a of the receiving device 20a converts the signal output from the AD converter unit 22a in step S14 from a high-frequency signal to a low-frequency baseband signal (step S15 in FIG. 2), and outputs the converted signal to the Doppler shift estimating and compensating unit 25a. Note that the spectrum of the signal output from the downconverter unit 23a in step S15 is converted to a baseband signal, for example, as shown in (4) in FIG. ｄ [Hz], and the bandwidth is f ｗ The spectrum is (1+v / c) [Hz].

[0033] Next, in step S15, the Doppler shift estimating / compensating unit 25a of the receiving device 20a estimates the Doppler shift that occurred when the receiving device 20a receives the sound wave A2 from the transmitting device 10a for the signal output from the downconverter unit 23a, corrects the Doppler shift by performing carrier frequency correction and resampling (step S16 in FIG. 2), and outputs the signal to the matched filter unit 26a. Note that the spectrum of the signal output from the Doppler shift estimating / compensating unit 25a in step S16 is, for example, a spectrum having a center frequency of 0 [Hz] and a bandwidth of f as shown in (5) in FIG. 3, in order to remove the Doppler shift that occurred when the receiving device 20a receives the transmission signal from the transmitting device 10a. ｗ The spectrum is in Hz.

[0034] Next, in step S16, the matched filter unit 26a of the receiving device 20a calculates the Doppler shift signal output from the Doppler shift estimation and compensation unit 25a in accordance with the band f used on the transmitting device 10a side. ｚ The signal in the transmission band is extracted by performing band limitation in step S17 and output to the equalization unit 27a. Note that the spectrum of the signal output from the matched filter unit 26a in step S17 is band-limited to the transmission band, so that, for example, as shown in (6) of FIG. 3, the center frequency is 0 [Hz] and the bandwidth is f ｗ The spectrum is in Hz.

[0035] Next, the equalizer 27a of the receiver 20a performs automatic equalization on the signal output from the matched filter unit 26a in step S17 to compensate for multipath distortion (step S18 in FIG. 2).

[0036] In the conventional receiver 20 (FIG. 8), when processing is performed in the matched filter unit 26, as shown in (5) of FIG. 9, a predetermined width f is subtracted from the spectrum bandwidth. ｌｏｓｓ In the first embodiment of the present invention, as shown in Fig. 1, the matched filter unit 26 is arranged after the Doppler shift estimating and compensating unit 25a. According to the receiving device 20a of the first embodiment of the present invention, when processing is performed by the Doppler shift estimating and compensating unit 25a, the center frequency can be shifted to 0 [Hz] as shown in (5) of Fig. 3, and when processing is performed by the matched filter unit 26a, the center frequency can be shifted to 0 [Hz] as shown in (6) of Fig. 3. ｗ Since it is possible to prevent a portion of the [Hz] from being lost, the problem of deterioration in communication quality can be solved.

[0037] [Second Embodiment] Next, a second embodiment of the present invention will be described. Fig. 4 is a schematic configuration diagram of an underwater acoustic communication system 100b according to the second embodiment of the present invention. The underwater acoustic communication system 100b includes a transmitting device 10b and a receiving device 20b. The transmitting device 10b and the receiving device 20b are installed underwater 50. A sound wave A3 is transmitted from the transmitting device 10b to the receiving device 20b, whereby data is transmitted from the transmitting device 10b to the receiving device 20b.

[0038] The transmitting device 10b, receiving unit 21b, AD converter unit 22b, down converter unit 23b, Doppler shift estimating and compensating unit 25b, matched filter unit 26b, equalizer unit 27b, control unit 30b, and storage unit 40b according to the second embodiment have the same configurations and perform the same processing as the transmitting device 10a, receiving unit 21a, AD converter unit 22a, down converter unit 23a, Doppler shift estimating and compensating unit 25a, matched filter unit 26a, equalizer unit 27a, control unit 30a, and storage unit 40a according to the first embodiment, and therefore will not be described again.

[0039] The receiving device 20b according to the second embodiment differs from the receiving device 20a according to the first embodiment, which does not include a band-limiting filter, in that it includes a band-limiting filter unit 24b. The band-limiting filter unit 24b is connected to a downconverter unit 23b and a Doppler shift estimating and compensating unit 25b. The band-limiting filter unit 24b removes bands other than a predetermined pass band from the input signal.

[0040] 5A, 5B, and 5C are diagrams illustrating a method for setting a passband in the band-limiting filter unit 24b according to the second embodiment of the present invention. The band-limiting filter unit 24b sets the passband so as to maximize the SNR (Signal-to-Noise Ratio) in the Doppler shift estimation and compensation unit 25b. That is, as will be described later, the passband f ｙ is set to the width between the maximum positive Doppler frequency deviation and the maximum negative frequency deviation.

[0041] FIG. 5A shows the spectrum of the transmission signal transmitted by the transmitting device 10b, with the center frequency f ｃ [Hz], and the bandwidth is f ｗ In FIG. 5A, the frequency (f ｃ -f ｗ / 2) [Hz] to frequency (f ｃ +f ｗ The spectrum of the transmitted signal is located at 1 / 2 [Hz].

[0042] FIG. 5B shows the maximum negative direction (moving away direction −v ｍａｘ ) is applied to the Doppler shift of (1-v ｍａｘ / c) (f ｃ -f ｗ 5A by 1 / 2) [Hz].

[0043] FIG. 5C shows the maximum positive direction (approaching direction +v ｍａｘ ) is applied to the Doppler shift of (1 + v ｍａｘ / c) (f ｃ+f ｗ 5A by 1 / 2) [Hz].

[0044] That is, the pass band f of the band limiting filter unit 24b is set within the range of the expected Doppler shift. ｙ By setting (1-v ｍａｘ / c) (f ｃ -f ｗ / 2) [Hz] to (1 + v ｍａｘ / c) (f ｃ +f ｗ / 2) [Hz]. The band-limiting filter unit 24b may also process the band of the baseband signal. In this case, the passband f ｙ , -f ｗ / 2-v ｍａｘ / c(f ｃ -f ｗ / 2) [Hz] to +f ｗ / 2+v ｍａｘ / c(f ｃ +f ｗ / 2) [Hz].

[0045] 6 is a sequence diagram showing the processing in the underwater acoustic communication system 100b according to the second embodiment of the present invention. First, the transmitting device 10b generates a baseband signal based on data to be transmitted to the receiving device 20b (step S21 in FIG. 6). The spectrum of the baseband signal generated by the transmitting device 10b in step S21 may have a center frequency of 0 [Hz] and a bandwidth of f, as shown in FIG. 7(1). ｗ The spectrum is in Hz.

[0046] Next, the transmitting device 10b performs transmission processing such as modulation and encoding on the baseband signal generated in step S21 to generate a transmission signal, and transmits the transmission signal as a sound wave to the receiving device 20b (step S22 in FIG. 6). Note that, due to the transmission processing, the spectrum of the transmission signal transmitted by the transmitting device 10b in step S22 may be, for example, a spectrum having a center frequency of f ｃ[Hz], and the bandwidth is f ｗ The spectrum is in Hz.

[0047] The receiving section 21b of the receiving device 20b receives the transmission signal transmitted by the transmitting device 10b in step S22 (step S23 in FIG. 6), and outputs the received signal to the AD converter section 22b.

[0048] Next, the AD converter unit 22b of the receiving device 20b quantizes the signal output from the receiving unit 21b in step S23, converting it from an analog signal to a digital signal (step S24 in FIG. 6), and outputs it to the downconverter unit 23b. Note that the spectrum of the signal output from the AD converter unit 22b in step S24 may be different from that of the signal having a center frequency of f as shown in (3) of FIG. 7 due to the Doppler shift that occurs between the transmitting device 10b and the receiving device 20b. ｃ +(v / c)f ｃ [Hz], and the bandwidth is f ｗ The spectrum is (1+v / c) [Hz].

[0049] Next, in step S24, the downconverter unit 23b of the receiver 20b converts the signal output from the AD converter unit 22b from a high frequency signal to a low frequency baseband signal (step S25 in FIG. 6), and outputs the converted signal to the band-limiting filter unit 24b. Note that the spectrum of the signal output from the downconverter unit 23b in step S25 is, for example, a spectrum having a center frequency of f as shown in (4) in FIG. ｄ [Hz], and the bandwidth is f ｗ The spectrum is (1+v / c) [Hz].

[0050] Next, in step S25, the band-limiting filter unit 24b of the receiving device 20b filters the signal output from the down-converter unit 23b in a predetermined pass band f ｙ The spectrum of the signal output from the band-limiting filter unit 24b in step S26 is filtered out in a predetermined passband f ｙ Therefore, for example, as shown in (5) of FIG. 7, the center frequency isｄ [Hz], and the bandwidth is f ｗ The spectrum is (1+v / c) [Hz].

[0051] Next, in step S26, the Doppler shift estimating / compensating unit 25b of the receiving device 20b estimates the Doppler shift that occurred when the receiving device 20b received the sound wave A3 from the transmitting device 10b for the signal output from the band-limiting filter unit 24b, corrects the Doppler shift by performing carrier frequency correction and resampling (step S27 in Fig. 6 ), and outputs the signal to the matched filter unit 26b. Note that the spectrum of the signal output from the Doppler shift estimating / compensating unit 25b in step S26 is, for example, a spectrum having a center frequency of 0 [Hz] and a bandwidth of f as shown in (6) in Fig. 7, in order to remove the Doppler shift that occurred when the receiving device 20b received the transmission signal from the transmitting device 10b. ｗ The spectrum is in Hz.

[0052] Next, in step S26, the matched filter unit 26b of the receiving device 20b calculates the Doppler shift signal output from the Doppler shift estimation and compensation unit 25b in the band f used on the transmitting device 10b side. ｚ The signal in the transmission band is extracted by performing band limitation in step S28 and output to the equalization unit 27b. Note that the spectrum of the signal output from the matched filter unit 26b in step S28 is band-limited to the transmission band, so that, for example, as shown in (7) of FIG. 7, the center frequency is 0 [Hz] and the bandwidth is f ｗ The spectrum is in Hz.

[0053] Next, the equalizer 27b of the receiver 20b performs automatic equalization on the signal output from the matched filter unit 26b in step S28, thereby compensating for multipath distortion (step S29 in FIG. 6).

[0054] In the conventional receiver 20 (FIG. 8), when processing is performed in the matched filter unit 26, as shown in (5) of FIG. 9, a predetermined width f is subtracted from the spectrum bandwidth. ｌｏｓｓIn contrast, in the receiver 20b according to the second embodiment of the present invention, when processing is performed by the Doppler shift estimation and compensation unit 25b, the center frequency can be shifted to 0 [Hz] as shown in (6) of Fig. 7, and when processing is performed by the matched filter unit 26b, the spectrum bandwidth f ｗ Since it is possible to prevent a portion of the [Hz] from being lost, the problem of deterioration in communication quality can be solved.

[0055] Furthermore, in the second embodiment of the present invention, the band-limiting filter unit 24b is provided in front of the Doppler shift estimating / compensating unit 25b, and therefore the SNR (signal-to-noise power ratio) can be improved by the band-limiting filter unit 24b in front of the Doppler shift estimating / compensating unit 25b, and the estimation accuracy and compensation accuracy of the Doppler shift estimating / compensating unit 25b can be improved compared to the first embodiment.

[0056] At least some of the functions of the transmitting devices 10a and 10b and at least some of the functions of the receiving devices 20a and 20b in the above-described embodiments may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, read-only memories (ROMs), and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, and media that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as the server or client in such cases. Furthermore, the above program may be one that realizes part of the functions described above, or may be one that can realize the functions described above in combination with a program already recorded in a computer system, or may be one that is realized using a programmable logic device such as an FPGA.

[0057] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0058] The present invention can be applied to a receiving device and a receiving method that need to prevent degradation of communication quality due to suppression of some bands of a received signal when performing underwater acoustic communication.

[0059] DESCRIPTION OF SYMBOLS 10a, 10b... Transmitting device 20a, 20b... Receiving device 21a, 21b... Receiving section 22a, 22b... AD converter section 23a, 23b... Down converter section 24b... Band limiting filter section 25a, 25b... Doppler shift estimating and compensating section 26a, 26b... Matched filter section 27a, 27b... Equalization section 30a, 30b... Control section 40a, 40b... Storage section 100a, 100b... Underwater acoustic communication system

Claims

1. A receiving device comprising: a receiving unit that receives a transmission signal transmitted from a transmitting device as a received signal; a matched filter unit that limits the bandwidth of the received signal to the bandwidth of the transmission signal; and a Doppler shift estimation and correction unit that estimates and corrects Doppler shift for the received signal, wherein the matched filter unit is located after the Doppler shift estimation and correction unit.

2. The receiving device according to claim 1, further comprising a band-limiting filter section whose passband is wider than the transmission bandwidth, said band-limiting filter section being arranged in a stage preceding said Doppler shift estimation correction section.

3. A receiving apparatus according to claim 2, wherein the passband of the band-limiting filter is set to a width between the maximum Doppler frequency deviation in the positive direction and the maximum frequency deviation in the negative direction.

4. A receiving method comprising: a receiving process for receiving a transmission signal transmitted from a transmitting device as a received signal; a matched filter process for limiting the bandwidth of the received signal to the bandwidth of the transmission signal; and a Doppler shift estimation and correction process for estimating and correcting a Doppler shift for the received signal, wherein the matched filter process is performed after the Doppler shift estimation and correction process.

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