Underwater acoustic modem and underwater equipment including the same

Abstract

This invention discloses an underwater acoustic modem, comprising a signal processing module, an acoustic signal transmitting unit, and an acoustic signal receiving unit. The signal processing module converts output data transmitted from an upstream device into an output FSK modulated signal, and the acoustic signal transmitting unit outputs this output FSK modulated signal as a first acoustic signal. After the acoustic signal receiving unit converts a second acoustic signal into an input FSK modulated signal, the signal processing module repeatedly performs interference bit sampling processing P times on the input FSK modulated signal to obtain sampled input data, and performs decoding processing on the sampled input data to obtain input data for uploading to the upstream device. Therefore, the underwater acoustic modem of this invention can avoid erroneous bit determination caused by multipath effects, background noise, and sudden interference during underwater communication, and ensure the correctness and reliability of data transmission.

Claims

1. An underwater acoustic data transceiver, comprising: A communication interface; A signal processing module is coupled to the communication interface; A sound wave signal transmitting unit is coupled to the signal processing module; The system includes a sound wave signal receiving unit coupled to the signal processing module; wherein the signal processing module is configured to perform the following: receiving output data from an upstream device via the communication interface; encoding the output data into an output data packet; performing frequency shift keying (FSK) modulation processing on the output data packet to generate an output FSK signal; outputting the output FSK modulated signal as a first sound wave signal via the sound wave signal transmitting unit; receiving a second sound wave signal transmitted from an external device via the sound wave signal receiving unit; converting the second sound wave signal into an input FSK modulated signal carrying P bits via the sound wave signal receiving unit; repeatedly performing interference bit sampling processing on the input FSK modulated signal P times to extract a sampled input data containing P sampled bits from the input FSK modulated signal; performing decoding processing on the sampled input data to obtain input data; and uploading the input data to the upstream device via the communication interface. The signal processing module performs the anti-interference bit sampling operation on each bit, and the i-th anti-interference bit sampling operation includes the following steps: Within one logical bit duration of the i-th bit, perform Q frequency detection processing on the input FSK modulation signal to detect a plurality of carrier frequencies; perform an occurrence count on the plurality of carrier frequencies and use the carrier frequency with the highest occurrence count as a dominant frequency; and if the dominant frequency is equal to a first predetermined frequency, register the i-th sampled bit as bit 0; if the dominant frequency is equal to a second predetermined frequency, register the i-th sampled bit as bit 1; where P, Q, and i are all positive integers, the initial value of i is 1, and the maximum value of i is P.

2. The underwater acoustic data machine as described in claim 1, wherein, The communication interface is selected from any one of the following groups: universal asynchronous receiver / transmitter (UART) interface, inter-integrated circuit (I2C) interface, serial peripheral interface (SPI), 1-Wire communication interface, and system management bus (SMBus) interface.

3. The underwater acoustic data transmitter as described in claim 1, wherein, The logical bit duration is between 2ms and 7ms.

4. The underwater acoustic data transmitter as described in claim 1, wherein, The signal processing module performs a hard decision operation to determine whether the i-th bit is bit 1 or bit 0 based on the main frequency, and the hard decision operation includes the following steps: if the main frequency is equal to the first predetermined frequency, the sampled bit is registered as bit 0; if the main frequency is equal to the second predetermined frequency, the sampled bit is registered as bit 1; and if the main frequency is neither equal to the first predetermined frequency nor equal to the second predetermined frequency, the sampled bit is registered as a preset bit; wherein the preset bit value is selected from either bit 0 or bit 1.

5. The underwater acoustic data machine as described in claim 4, wherein, The signal processing module includes: an FSK modulation unit configured to perform the frequency shift keying modulation processing; an anti-interference bit sampling unit configured to perform the interference bit sampling processing; and a handshake and packet control unit configured to perform: when the underwater acoustic data transceiver is operating in a signal transmission mode, encoding the output data received from the upstream device into the output data packet and transmitting it to a receiving device also equipped with the underwater acoustic data transceiver, and then receiving a reply data packet from the receiving device; when the underwater acoustic data transceiver is operating in a signal reception mode, decoding the input data packet to obtain the input data, and generating the reply data packet based on the input data.

6. The underwater acoustic data machine as described in claim 5, wherein, The output data packet includes J start bits, L payload bits, and K end bits, where J, L, and K are all positive integers.

7. The underwater acoustic data transceiver as described in claim 5, wherein, The response data packet includes J start bits, R check bits, and K end bits, where J, R, and K are all positive integers.

8. The underwater acoustic data transmitter as described in claim 7, wherein, The check code bits are generated by performing a checksum operation on the decoded input data.

9. The underwater acoustic data transmitter as described in claim 5, wherein, The signal processing module is a microcontroller (MCU), a digital signal processor (DSP), or a field-programmable gate array (FPGA), and the handshake and packet control unit, the FSK modulation unit, and the anti-interference bit sampling unit are three logic function blocks configured within the signal processing module.

10. The underwater acoustic data transmitter as described in claim 9, wherein, The logic function module is selected from any one of the group consisting of IP cores, logic code, and hardware description language (HDL).

11. The underwater acoustic data transmitter as described in claim 5, wherein, The signal processing module is an application-specific integrated circuit (ASIC) chip or a system on chip (SoC). The handshake and packet control unit and the FSK modulation unit are two functional circuit modules configured within the signal processing module, and the anti-interference bit sampling unit is a logic functional module configured within the signal processing module.

12. The underwater acoustic data machine as described in claim 5, wherein, The anti-interference bit sampling unit includes: a frequency extractor configured to perform Q frequency detection processes on the input FSK modulation signal within the logical bit duration of the i-th bit, to detect Q carrier frequencies; a main frequency counter configured to perform the occurrence count statistics on the Q carrier frequencies and use the carrier frequency with the highest occurrence count as the main frequency; and a bit determiner configured to perform the hard decision operation.

13. The underwater acoustic data transmitter as described in claim 1 further includes: A power amplifier unit, coupled between the signal processing module and the acoustic signal transmitting unit, and configured to perform a power amplification process on the output FSK signal; an impedance matching unit, coupled between the power amplifier unit and the acoustic signal transmitting unit, and configured to perform: receiving the output FSK signal after the power amplification process from the power amplifier unit; performing an output impedance adjustment process on the output FSK signal; and transmitting the output FSK signal after the output impedance adjustment process to the acoustic signal transmitting unit; a signal amplification unit, coupled between the acoustic signal receiving unit, and configured to perform a signal amplification process on the input FSK modulation signal; and a signal preprocessing unit, coupled between the signal amplification unit and the signal processing module, and configured to perform: receiving the input FSK modulation signal after the signal amplification process from the signal amplification unit; Perform signal preprocessing on the input FSK modulation signal; and transmit the input FSK modulation signal, after completing the signal preprocessing, to the signal processing module.

14. The underwater acoustic data transceiver as described in claim 13, wherein, The impedance matching unit is selected from any of the group consisting of transformers, LC networks, pi-type impedance matchers, and active impedance matching circuits.

15. The underwater acoustic data center as described in claim 13, wherein, The signal preprocessing unit includes: a clipper configured to perform a clipping process on the input FSK modulated signal; and a level shifter coupled to the clipper and configured to perform a level shifting process on the input FSK modulated signal that has undergone the clipping process; wherein the signal preprocessing includes the clipping process and the level shifting process.

16. An underwater device, characterized in that it has at least one underwater acoustic data transmitter as described in any one of claims 1 to 15.

17. The underwater device as described in claim 16, wherein, The underwater device is selected from any one of the following groups: underwater monitoring stations, underwater sensor base stations, autonomous underwater vehicles (AUVs), surface buoys, semi-submersible buoys, underwater voice communication equipment, underwater positioning and navigation devices, portable data transmission devices, underwater bionic robots, and diver safety monitoring devices.

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