NAVDAT and NAVTEX modulators and modulation methods based on AES / EBU-IQ interface

Abstract

The present invention discloses a NAVDAT and NAVTEX modulator based on an AES / EBU‑IQ interface and a modulation method thereof, comprising a connected CPU module and an FPGA module, wherein the CPU module is connected to a first network port and a second network port, the FPGA module is connected to a digital-to-analog conversion interface, a digital audio interface and an analog audio interface, the CPU module obtains an original message file through the first network port, the CPU module modulates the original message file into IQ original data and sends it to the FPGA module, the FPGA module splits the IQ original data sent by the CPU module into data packets and modulates it into AES / EBU‑IQ format data; the digital-to-analog conversion interface, the digital audio interface and the analog audio interface convert the AES / EBU‑IQ format data into corresponding signal outputs. The present invention modulates the original information file into IQ original data, solving the problem of unified data format; multiple output interfaces are set to match multiple transmitters, and the broadcasting of NAVDAT and NAVTEX is satisfied at the same time.

Description

Technical Field

[0001] The present invention relates to a modulator and a modulation method thereof, and in particular to a NAVDAT and NAVTEX modulator based on an AES / EBU-IQ interface and a modulation method thereof. Background Art

[0002] The NAVTEX system is a dedicated broadcasting system for broadcasting navigation warnings, weather warnings, weather forecasts and other emergency information for ships sailing at sea. It is a component of the World Wide Navigation Warning Service (WWNWS). The dedicated frequency used by the NAVTEX system is 518KHz, and the FEC method of narrowband direct printing (NBDP) is adopted to broadcast maritime safety information to ships sailing along the coast. According to the equipment requirements of GMDSS equipment, ships sailing at sea are equipped with NAVTEX receivers to automatically receive and print the broadcasted maritime safety information.

[0003] NAVDAT is a new shore-based marine digital broadcasting system that uses the latest digital transmission technology to broadcast maritime safety and security-related information and other service information on 500kHz. The NAVDAT system can achieve coverage of the A2 sea area. NAVDAT can solve shore-to-ship digital broadcasting. The broadcast format includes messages, texts, files or images, and can quickly push navigation-related safety information such as chart correction information, and achieve seamless connection with ship information systems. NAVDAT can enhance the maritime information service capabilities and is a key system in GMDSS modernization and e-navigation. According to the WRC-12 meeting, NAVDAT was allocated a maritime mobile service frequency of 495–505kHz, using multi-carrier frequency modulation technology. NAVDAT will coexist with the NAVTEX system that has been in operation for a long time in the world, and ensure that there is no mutual interference. Compared with NAVTEX, the multi-carrier frequency modulation technology used by NAVDAT improves spectrum utilization, and the data rate can reach up to 18kbps, which is 360 times higher than NAVTEX's 50bps.

[0004] Both NAVTEX and NAVDAT equipment work in the intermediate frequency band, and their working frequencies are close. NAVDAT is a supplement and replacement for NAVTEX, and they will coexist for a period of time in the future. However, the two equipment are still independent devices, which makes it difficult to promote and promote the popularization and development of NAVDAT. If the equipment can be unified and the cost can be reduced, it will be conducive to the promotion of NAVDAT. The modulator of NAVTEX uses a 600-ohm balanced output, while the NAVDAT modulator uses the RF signal output after the DAC to directly drive the transmitter; AES / EBU is an uncompressed digital audio format that transmits high-quality digital audio data of two channels in a unidirectional serial code; the information file content is modulated into an IQ two-way signal, in which I and Q data are interleaved; Q data follows I data, and IQ data is transmitted using the two dual-channel transmission of Aes / Ebu, and combined into a transmission signal, solving the problem of data format unification. Therefore, it is necessary to design a NAVDAT and NAVTEX modulator and its modulation method based on AES / EBU-IQ interface, adopt AES / EBU digital audio format, unify the data format and match the original NAVTEX transmitter and NAVDAT transmitter. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface and a modulation method thereof, adopt different modulation algorithms to realize a unified data format, meet the broadcasting of NAVDAT and NAVTEX, provide a variety of interfaces to match NAVTEX transmitters, NAVDAT transmitters and medium wave digital transmitters, and have a wide range of applications.

[0006] The technical solution adopted by the present invention to solve the above technical problems is to provide a NAVDAT and NAVTEX modulator based on an AES / EBU-IQ interface, including a CPU module and an FPGA module connected to each other, the CPU module is connected to a first network port and a second network port, the FPGA module is connected to a digital-to-analog conversion interface, a digital audio interface and an analog audio interface, the CPU module obtains an original message file through the first network port, the CPU module modulates the original message file into IQ original data and sends it to the FPGA module, the FPGA module splits the IQ original data sent by the CPU module into data packets and modulates them into AES / EBU-IQ format data; the digital-to-analog conversion interface converts the AES / EBU-IQ format data into an analog signal output; the digital audio interface converts the AES / EBU-IQ format data into an AES / EBU-IQ digital signal output; the analog audio interface converts the AES / EBU-IQ format data into a 600 ohm audio output.

[0007] Furthermore, the second network port adopts the SNMP protocol, and the CPU module communicates with the transmitter through the second network port, controls the transmitter and synchronizes the transmitter status from the transmitter at regular intervals; the first network port adopts the TCP / IP protocol, and the CPU module is connected to the remote control terminal through the first network port, obtains the original message file from the remote control terminal, and synchronizes the transmitter status to the remote control terminal.

[0008] Furthermore, the digital-to-analog conversion interface matches a NAVDAT transmitter, the analog audio interface matches a NAVTEX transmitter, and the digital audio interface matches a medium wave digital transmitter.

[0009] Furthermore, the CPU module is connected to a RAM module, which stores the acquired original message file and the IQ original data obtained by modulation processing; the FPGA module is connected to an SDRAM module, which stores the IQ original data and the AES / EBU-IQ format data obtained by modulation.

[0010] Furthermore, the FPGA module is connected to a GPS module and a TCXO module, the GPS module provides a positioning signal; the TCXO module provides a reference clock signal.

[0011] Furthermore, the first network port and the second network port are connected to the CPU module via a PHY module and a MAC module respectively.

[0012] Another technical solution adopted by the present invention to solve the above technical problems is to provide a modulation method of NAVDAT and NAVTEX modulators based on AES / EBU-IQ interface, characterized in that it includes the following steps:

[0013] S1: The CPU module connects to the remote control terminal through the first network port to obtain the original message file and store it; S2: The CPU module selects the corresponding modulation method according to the broadcast mode, modulates the original message file into IQ original data and sends it to the FPGA module; S3: The FPGA module splits the IQ original data sent by the CPU module into data packets and modulates them into AES / EBU-IQ format data; S4: The FPGA module selects the corresponding output interface according to the broadcast mode to send AES / EBU-IQ format data.

[0014] Furthermore, the broadcast mode includes NAVDAT mode and NAVTEX mode. When the broadcast mode is NAVDAT mode, the modulation method used is OFDM / nQAM modulation, and the FPGA module selects the digital-to-analog conversion interface to convert AES / EBU-IQ format data into analog signal output or selects the digital audio interface to convert AES / EBU-IQ format data into AES / EBU-IQ digital signal output; when the broadcast mode is NAVTEX mode, the modulation method used is F1B modulation, and the FPGA module selects the analog audio interface to convert AES / EBU-IQ format data into 600 ohm audio output or selects the digital audio interface to convert AES / EBU-IQ format data into AES / EBU-IQ digital signal output.

[0015] Furthermore, the CPU module is also included to connect the transmitter through the second network port to synchronize the transmitter status regularly, and synchronize the transmitter status to the remote control terminal connected to the first network port.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the NAVDAT and NAVTEX modulators and modulation methods based on the AES / EBU-IQ interface provided by the present invention modulate the original information file content into IQ original data, solving the problem of data format unification; multiple output interfaces are set, the digital-to-analog conversion interface matches the traditional NAVDAT transmitter, the analog audio interface matches the NAVTEX transmitter, and the digital audio interface AES / EBU-IQ matches the digital transmitter, while meeting the broadcasting of NAVDAT and NAVTEX; multiple network ports are set, and the TCP / IP protocol is connected to the remote control terminal for message publishing and transmitter status monitoring; the SNMP protocol is used for communication between the modulator and the transmitter to realize the control of the transmitter and update the transmitter status information at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram of the architecture of NAVDAT and NAVTEX modulators based on the AES / EBU-IQ interface in an embodiment of the present invention;

[0018] Figure 2 It is a modulation flow chart of NAVDAT and NAVTEX modulators based on AES / EBU-IQ interface in an embodiment of the present invention;

[0019] Figure 3 It is a flow chart of data processing of NAVDAT and NAVTEX modulators, remote control terminals and transmitters based on AES / EBU-IQ interface in an embodiment of the present invention;

[0020] Figure 4Schematic diagram of the AES / EBU-IQ data frame structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 4 is a diagram of the architecture of the NAVDAT and NAVTEX modulators based on the AES / EBU-IQ interface in an embodiment of the present invention.

[0023] See also Figure 1 The NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface of the embodiment of the present invention comprises a CPU module and an FPGA module connected to each other, the CPU module is connected to a first network port and a second network port, the FPGA module is connected to a digital-to-analog conversion interface, a digital audio interface and an analog audio interface, the CPU module obtains the original message file through the first network port, the CPU module modulates the original message file into IQ original data and sends it to the FPGA module, the FPGA module splits the IQ original data sent by the CPU module into data packets and modulates them into AES / EBU-IQ format data; the digital-to-analog conversion interface converts the AES / EBU-IQ format data into analog signal output; the digital audio interface converts the AES / EBU-IQ format data into AES / EBU-IQ digital signal output; the analog audio interface converts the AES / EBU-IQ format data into 600 ohm audio output.

[0024] Specifically, the second network port adopts the SNMP protocol, and the CPU module communicates with the transmitter through the second network port, controls the transmitter and synchronizes the transmitter status from the transmitter at regular intervals; the first network port adopts the TCP / IP protocol, and the CPU module is connected to the remote control terminal through the first network port, obtains the original message file from the remote control terminal, and synchronizes the transmitter status to the remote control terminal.

[0025] Specifically, the digital-to-analog conversion interface matches the NAVDAT transmitter, the analog audio interface matches the NAVTEX transmitter, and the digital audio interface matches the medium wave digital transmitter.

[0026] Specifically, the CPU module is connected to a RAM module, which stores the acquired original message file and the IQ original data obtained by modulation processing; the FPGA module is connected to an SDRAM module, which stores the IQ original data and the AES / EBU-IQ format data obtained by modulation.

[0027] Preferably, the FPGA module is connected to a GPS module and a TCXO module, the GPS module provides a positioning signal; the TCXO module provides a reference clock signal.

[0028] Preferably, the first network port and the second network port are connected to the CPU module via a PHY module and a MAC module respectively.

[0029] Please also see Figure 2 The debugging method of the NAVDAT and NAVTEX modulators based on the AES / EBU-IQ interface of the embodiment of the present invention comprises the following steps:

[0030] S1: The CPU module connects to the remote control terminal through the first network port to obtain the original message file and store it;

[0031] S2: The CPU module selects the corresponding modulation mode according to the broadcast mode, modulates the original message file into IQ original data, and sends it to the FPGA module;

[0032] S3: The FPGA module splits the IQ raw data sent by the CPU module into data packets and modulates them into AES / EBU-IQ format data;

[0033] S4: The FPGA module selects the corresponding output interface to send AES / EBU-IQ format data according to the broadcast mode.

[0034] Specifically, the broadcast mode includes NAVDAT mode and NAVTEX mode. When the broadcast mode is NAVDAT mode, the modulation method used is OFDM / nQAM modulation, n is 4, 16 or 64, namely 4QAM, 16QAM or 64QAM. This modulation method is a prior art and is not described here; the FPGA module selects the digital-to-analog conversion interface to convert the AES / EBU-IQ format data into an analog signal output or selects the digital audio interface to convert the AES / EBU-IQ format data into an AES / EBU-IQ digital signal output; when the broadcast mode is NAVTEX mode, the modulation method used is F1B modulation, which is a prior art and is not described here; the FPGA module selects the analog audio interface to convert the AES / EBU-IQ format data into a 600 ohm audio output or selects the digital audio interface to convert the AES / EBU-IQ format data into an AES / EBU-IQ digital signal output.

[0035] Specifically, the CPU module is connected to the transmitter through the second network port to synchronize the transmitter status regularly, and synchronizes the transmitter status to the remote control terminal connected to the first network port.

[0036] Please also see Figure 3In the NAVDAT and NAVTEX modulators based on the AES / EBU-IQ interface of the embodiment of the present invention, when actually used, the WEB interface of the information center of the remote control terminal manages the original message file to be sent and sets the parameters required for sending. The original message file can be a message of editable text, picture and file type; the information center saves the original message file to the local database, and synchronizes the saved original message file to the modulator; the modulator background program stores the original message file to the modulator memory; the modulator background program generates the message queue of the day at a fixed time every day; and at each designated transmission time point, the time period is synchronized All messages to be sent are pushed to the transmitter control program; the modulator background program is deployed in the CPU module, and the background program modulates the data according to the broadcast mode to generate IQ raw data; after receiving the message, the transmitter control program sends the message to the local transmission queue, and cyclically takes the latest message from the queue head, splits the data packet modulated data into two AES / EBU-IQ signals, and sends them to the transmitter; the transmitter control program is deployed in the FPGA module, converts the IQ raw data into AES / EBU-IQ data; the transmitter receives the two AES / EBU-IQ signals from the modulator, processes them, and then transmits the modulated signals. After the message is transmitted, the transmitter control program updates the transmitter transmission status, and the transmitter control program transmits the status information to the information center through the network; the transmitter synchronizes its own status to the transmitter control program regularly through the SNMP protocol, and forwards it to the remote control terminal through the transmission station.

[0037] See also Figure 4 , AES / EBU-IQ data frame, one frame is divided into subframe A and subframe B. Subframe A and subframe B are composed of 32 bits, which are: 4 bits of synchronization symbol, 4 bits of auxiliary data, 20 bits of I channel data, 1 bit each of V (legal mark), U (user data), C (channel status), and P (data check).

[0038] In summary, the NAVDAT and NAVTEX modulators and modulation methods based on the AES / EBU-IQ interface of the embodiments of the present invention modulate the original information file content into IQ original data, solving the problem of unified data format; multiple output interfaces are set, the digital-to-analog conversion interface matches the traditional NAVDAT transmitter, the analog audio interface matches the NAVTEX transmitter, and the digital audio interface AES / EBU-IQ matches the digital transmitter, while meeting the broadcasting of NAVDAT and NAVTEX; multiple network ports are set, and the TCP / IP protocol is connected to the remote control terminal for message publishing and transmitter status monitoring; the SNMP protocol is used for communication between the modulator and the transmitter to realize the control of the transmitter and update the transmitter status information at the same time.

[0039] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A NAVDAT and NAVTEX modulator based on AES / EBU-IQ interface, characterized in that: It includes a connected CPU module and an FPGA module, the CPU module is connected to a first network port and a second network port, the FPGA module is connected to a digital-to-analog conversion interface, a digital audio interface and an analog audio interface, the CPU module obtains an original message file through the first network port, the CPU module modulates the original message file into IQ original data and sends it to the FPGA module, the FPGA module splits the IQ original data sent by the CPU module into data packets and modulates them into AES / EBU-IQ format data; the digital-to-analog conversion interface converts the AES / EBU-IQ format data into analog signal output; the digital audio interface converts the AES / EBU-IQ format data into AES / EBU-IQ digital signal output; the analog audio interface converts the AES / EBU-IQ format data into 600 ohm audio output.

2. The NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface according to claim 1, characterized in that: The second network port adopts the SNMP protocol, and the CPU module communicates with the transmitter through the second network port, controls the transmitter and synchronizes the transmitter status from the transmitter at regular intervals; the first network port adopts the TCP / IP protocol, and the CPU module is connected to the remote control terminal through the first network port, obtains the original message file from the remote control terminal, and synchronizes the transmitter status to the remote control terminal.

3. The NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface as claimed in claim 2, characterized in that: The digital-to-analog conversion interface matches the NAVDAT transmitter, the analog audio interface matches the NAVTEX transmitter, and the digital audio interface matches the medium wave digital transmitter.

4. The NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface as claimed in claim 1, characterized in that: The CPU module is connected to a RAM module, which stores the acquired original message file and the IQ original data obtained by modulation processing; the FPGA module is connected to an SDRAM module, which stores the IQ original data and the AES / EBU-IQ format data obtained by modulation.

5. The NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface as claimed in claim 1, characterized in that: The FPGA module is connected to a GPS module and a TCXO module. The GPS module provides a positioning signal; the TCXO module provides a reference clock signal.

6. The NAVDAT and NAVTEX modulator based on the AES / EBU-IQ interface as claimed in claim 1, characterized in that: The first network port and the second network port are connected to the CPU module through the PHY module and the MAC module respectively.

7. A modulation method of NAVDAT and NAVTEX modulator based on AES / EBU-IQ interface as claimed in any one of claims 1 to 6, characterized in that: The steps include: S1: The CPU module connects to the remote control terminal through the first network port to obtain the original message file and store it; S2: The CPU module selects the corresponding modulation mode according to the broadcast mode, modulates the original message file into IQ original data, and sends it to the FPGA module; S3: The FPGA module splits the IQ raw data sent by the CPU module into data packets and modulates them into AES / EBU-IQ format data; S4: The FPGA module selects the corresponding output interface to send AES / EBU-IQ format data according to the broadcast mode.

8. The modulation method according to claim 7, characterized in that: The broadcast mode includes NAVDAT mode and NAVTEX mode. When the broadcast mode is NAVDAT mode, the modulation method used is OFDM / nQAM modulation. The FPGA module selects the digital-to-analog conversion interface to convert AES / EBU-IQ format data into analog signal output or selects the digital audio interface to convert AES / EBU-IQ format data into AES / EBU-IQ digital signal output; when the broadcast mode is NAVTEX mode, the modulation method used is F1B modulation. The FPGA module selects the analog audio interface to convert AES / EBU-IQ format data into 600 ohm audio output or selects the digital audio interface to convert AES / EBU-IQ format data into AES / EBU-IQ digital signal output.

9. The modulation method according to claim 7, characterized in that: It also includes a CPU module that connects to the transmitter through the second network port to synchronize the transmitter state regularly, and synchronizes the transmitter state to the remote control terminal connected to the first network port.

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