JP2014175790A - Data transmission system, synchronous data transmission apparatus and synchronous data receiving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transmission system, a synchronous data transmission apparatus and a synchronous data receiving apparatus capable of obtaining and synchronizing clock signals having almost the same frequency and phase between a data transmission apparatus and a data receiving apparatus which are respectively independently installed.SOLUTION: The data transmission system comprises: the synchronous data transmission apparatus including transmission side clock signal generation means for generating a transmission side reference clock signal to be a transmission side reference from a carrier wave received from a specified satellite through a transmission side antenna and data signal generation/sending means for generating and sending a data signal on the basis of the transmission side reference signal generated by the transmission side clock signal generation means; and the synchronous data receiving apparatus including receiving side clock signal generation means for generating a receiving side reference clock signal from a carrier wave received from the satellite through a receiving side antenna and data receiving/reproducing means for receiving a data signal sent from the synchronous data transmission apparatus on the basis of the receiving side reference signal generated by the receiving side clock signal and reproducing data.

Description

  Embodiments described herein relate generally to a data transmission system including independent data transmission apparatuses and data reception apparatuses.

  There is a data transmission system in which a data transmission device and a data reception device are installed at remote locations. In such a system, since the data transmission device and the data reception device are separated from each other, it is difficult to obtain a reference signal (clock signal) generated from the same oscillation source. Usually, a reference signal generated from a different oscillation source is used. It must be used and synchronized.

  In such a case, when constructing a synchronous transfer system having the same transfer band between these transmitting and receiving apparatuses, a slight error of the reference signal naturally occurs, and the band performance possessed by the data transmitting apparatus and the data receiving apparatus is completely the same. do not do.

  In general, when data is transferred from one device to the other device with the same design bandwidth when the bandwidths between the devices are different, there is a possibility that data loss occurs. Therefore, normally, the effective band is narrowed by lowering the transfer duty, or the band is absorbed by providing a temporary buffer on the receiving side.

  However, in a system that requires continuous transfer, it is not possible to provide a buffer, and it is necessary to design a band higher than the actual transfer rate, and efficient transfer cannot be performed.

  The reference signal generated from the same oscillation source may be used. However, when the data transmission device and the data reception device are separated as described above, the reference signal is generated from the same oscillation source. Is difficult.

Japanese Patent Laid-Open No. 11-150531

  An object of the present invention is to provide a data transmission system, a synchronous data transmission device, and a synchronous data reception device capable of obtaining and synchronizing clock signals having substantially the same frequency and phase between independently provided data transmission devices and data reception devices. Is to get.

  In one embodiment, a transmitting-side antenna that receives a carrier wave from a specified satellite, and a transmitting-side clock signal generator that generates a transmitting-side reference clock signal that serves as a transmitting-side reference from the carrier wave received by the transmitting-side antenna And a synchronous data transmission device having data signal generation and transmission means for generating and transmitting a data signal based on the transmission side reference signal generated by the transmission side clock signal generation means, and the carrier wave from the satellite Generated by the receiving side clock signal generating means, a receiving side clock signal generating means for generating a receiving side reference clock signal serving as a receiving side reference from the carrier wave received by the receiving side antenna, and the receiving side clock signal generating means Based on the receiving side reference signal, the data signal sent from the synchronous data transmitting device is received. To provide a data transmission system characterized by having a synchronous data receiver having a data receiving and reproducing means for reproducing the data.

It is a figure which shows the whole system configuration | structure of one Embodiment. It is a figure which shows the structural example of the synchronous data transmission apparatus of one Embodiment. It is a figure which shows the structural example of the synchronous data receiver of one Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A configuration example of a data transmission system according to an embodiment is shown in FIG. In this example, a case where a GNSS (Global Navigation Satellite System) is used as a satellite will be described. This data transmission system includes a synchronous data transmitting device 12 and a synchronous data receiving device 13 that receive a signal including a carrier wave from the GNSS satellite 11.

  The synchronous data transmission device 12 includes a GNSS antenna 14 that is a transmitting antenna that receives a signal from the GNSS satellite 11, a GNSS clock recovery unit 15 that transmits a GNSS clock from a signal received by the GNSS antenna, A transmission data processing unit 16 that is supplied with the clock signal reproduced by the GNSS clock reproduction unit 15, generates transmission data, processes the data, and transmits the transmission data.

  In addition, the synchronous data receiving device 13 includes a GNSS antenna 17 that is a receiving antenna that receives a signal from the GNSS satellite 11, and a GNSS clock recovery unit 18 that recovers a clock signal from the signal received by the GNSS antenna 17. And a received data processing unit 19 that is supplied with the clock signal regenerated by the GNSS clock regenerating unit 18 and receives, processes, and regenerates the data signal transmitted from the synchronous data transmitting apparatus.

  A more detailed configuration example of the synchronous data transmission device 12 is shown in FIG. The GNSS clock recovery unit 15 of the synchronous data transmission device 12 includes a GNSS reception processing unit 21 connected to the GNSS antenna 14 and a carrier that detects the carrier from the received signal from the GNSS satellite received by the GNSS reception processing unit 21. A detection unit 22 and a GNSS clock extraction unit 23 that extracts a GNSS clock signal from the GNSS carrier detected by the carrier detection unit 22 and supplies the GNSS clock signal to each unit.

  The transmission data processing unit 16 includes a data generation unit 24 that generates data scheduled for synchronous transmission, a data storage unit 25 that temporarily stores data generated in the data generation unit 24, and data stored in the data storage unit 25 A synchronization processing unit 26 for synchronizing the data and a data transmission processing unit 27 for transmitting the data subjected to the synchronization processing.

  The GNSS clock signal obtained by the GNSS clock extraction unit 23 is supplied as a reference clock signal to the data generation unit 24, the data storage unit 25, the synchronization processing unit 26, and the data transmission processing unit 27.

  The data sent from the data transmission processing unit 27 of the synchronous data transmitting device 12 is sent to the synchronous data receiving device 13 via a transmission line, for example.

  A configuration example of the synchronous data receiving device 13 is shown in FIG. The synchronous data receiving device 13 includes a GNSS antenna 17, a GNSS clock recovery unit 18, and a received data processing unit 19.

  The GNSS clock recovery unit 18 includes a GNSS reception processing unit 31 connected to the GNSS antenna 17, a carrier detection unit 32 that detects a carrier wave from a received signal from a GNSS satellite received by the GNSS reception processing unit 31, and a carrier wave A GNSS clock extraction unit 33 that extracts a GNSS clock signal from the GNSS carrier detected by the detection unit 32 and supplies the GNSS clock signal to each unit.

  The reception data processing unit 19 includes a data reception processing unit 34 that receives and processes the synchronous data transmitted from the synchronous data transmitting device 12, a sampling unit 35 that samples the data processed in the data reception processing unit 34, and the sampling A data reproducing unit 36 for reproducing the data processed by the unit 35, a data storage unit 37 for storing the reproduced digital data, and data for performing video processing, analysis processing, etc. on the data stored in the data storage unit 37 And a processing unit 38.

  The GNSS clock signal obtained by the GNSS clock extraction unit 33 is supplied as a reference clock signal to the data reception processing unit 34, the sampling unit 35, the data reproduction unit 36, the data storage unit 37, and the data processing unit 38.

  The operation of this embodiment will be described. First, a carrier wave signal from the GNSS satellite 11 is constantly transmitted. In order to obtain a clock signal having the same frequency and the same phase in the synchronous data transmitting device 12 and the synchronous data receiving device 13, the carrier signal transmitted from the GNSS satellite 11 is obtained from the GNSS antenna 14 of the synchronous data transmitting device 12 and the synchronous data reception. It is necessary to receive directly at the GNSS antenna 17 of the device 17. Moreover, it is preferable to use a GNSS satellite located at an azimuth and an elevation where both reception conditions are the same. Therefore, either one of the synchronous data transmitting device 12 and the synchronous data receiving device 13 designates which GNSS satellite is used to perform a common clock signal as a reference, and the other identifies the satellite according to the instruction. Then, when the position of the satellite with respect to the synchronization data transmitting device 12 and the synchronization data receiving device 13 is greatly deviated and biased as described above, the clock signal may be used using another GNSS satellite.

  When a geostationary satellite having a fixed position with respect to the earth is desirable in the positional relationship between the synchronous data transmitting device 12 and the synchronous data receiving device 13, the positional relationship does not change and is most preferable in terms of the positional relationship. A quasi-zenith satellite that can always receive signals stably at a high elevation angle is also an effective option. Here, a case where a GNSS satellite is used is described.

  In Japan, this GNSS satellite, geostationary satellite-type satellite navigation augmentation system (MSAS), or quasi-zenith satellite (QZSS) may be selected.

  As described above, both the synchronous data transmitting device 12 and the synchronous data receiving device 13 receive the carrier wave signal from the same selected GNSS satellite within the line-of-sight range of both devices. Specifically, the synchronous data transmission device 12 receives a carrier signal by the GNSS antenna 14 shown in FIG. 2, detects the carrier by the carrier detector 22, and extracts the clock signal of the GNSS satellite 11 by the GNSS clock extractor 23. To do. The GNSS clock signal extracted by the GNSS clock extraction unit 23 is supplied as a reference clock signal to the data data generation unit 24, the data storage unit 25, the synchronization processing unit 26, and the data transmission processing unit 27.

  Digital data generated by the data generator 24 or digital data converted from analog data by AD conversion is stored in the data storage unit 25. Thereafter, the stored data is synchronized by the synchronization processing unit 26 and transmitted from the data transmission processing unit 27 to the reception data processing unit 19 of the synchronous data receiving device 13.

  In the synchronous data receiving device 13, a carrier wave signal transmitted from the GNSS satellite 11 is received by the GNSS antenna 17. This carrier signal is received and processed by the GNSS reception processor 31 shown in FIG. 3, and the carrier is detected by the carrier detector 32. A GNSS clock signal is extracted from the detected carrier wave by the GNSS clock extraction unit 33, and the extracted clock signal is used as a reference clock signal as a data reception processing unit 34, sampling unit 35, data reproduction unit 36, and data storage unit 37. And supplied to the data processing unit 38. The digital data signal transmitted from the data transmission processing unit 27 of the synchronous data transmission device 12 is received and processed by the data reception processing unit 34 and sampled at a predetermined sampling frequency by the sampling unit 35. This sampling is created by multiplying or dividing the reference clock signal sent from the GNSS clock extraction unit 33.

  The data sampled by the sampling unit 35 is reproduced by the data reproduction unit 36 and reproduced as digital data. The reproduced digital data is then temporarily stored in the data storage unit 37 and sent to the data processing unit 38.

  Thus, in this embodiment, both the synchronous data transmitting device 12 and the synchronous data receiving device 13 create the reference clock signal from the carrier wave received from the same satellite, for example, the GNSS satellite. Therefore, the reference clock signals of both the synchronous data transmitting device 12 and the synchronous data receiving device 13 are almost exactly matched in frequency and phase.

  Therefore, a data transmission system and a data reception device provided independently, which can obtain and synchronize clock signals having the same frequency and phase almost accurately between the data transmission device and the data reception device provided independently. It is possible to obtain a data transmission system, a synchronous data transmitting device, and a synchronous data receiving device that can obtain and synchronize clock signals having substantially the same frequency and phase in between.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

11. GNSS satellite 11
12... Synchronous data transmitter 13... Synchronous data receiver 14, 17... GNSS antenna 15, 18... GNSS clock recovery unit 16. ··· Received data processing unit 21, 31 ··· GNSS reception processing unit 22, 32 ··· Carrier detection unit 23, 33 ··· GNSS clock extraction unit 24 ··· Data generation unit 25, 37 ... Data storage unit 26 ... Synchronization processing unit 27 ... Data transmission processing unit 34 ... Data reception processing unit 35 ... Sampling unit 36 ... Data reproduction unit 38 ... ..Data processing section

Claims (4)

A transmitting antenna that receives the carrier from the identified satellite;
Based on the transmission side reference signal generated by the transmission side clock signal generating means for generating the transmission side reference clock signal which becomes the reference of the transmission side from the carrier wave received by the transmission side antenna, and the transmission side clock signal generation means A data signal generation and transmission means for generating and transmitting a data signal, and a synchronous data transmission device having
A receiving antenna that receives the carrier from the satellite;
Based on the receiving side reference signal generated by the receiving side clock signal generating means for generating the receiving side reference clock signal which becomes the receiving side reference from the carrier wave received by the receiving side antenna, and the receiving side clock signal generating means A data receiving / reproducing means for receiving and processing the data signal transmitted from the synchronous data transmitting device and reproducing the data;
A data transmission system comprising: A transmitting antenna that receives the carrier from the identified satellite;
A transmission side carrier detector for detecting a carrier wave from the carrier wave received by the transmission side antenna;
A transmission-side clock signal extraction unit that extracts a clock signal from the carrier wave detected by the transmission-side carrier wave detection unit;
The clock signal extracted by the transmission-side clock signal extraction unit operates as a transmission-side reference clock signal and is transmitted to a synchronous data receiving device that performs reception processing in synchronization with the clock signal extracted from the carrier wave received from the specified satellite. A synchronous transmission processing unit for synchronously processing and transmitting data to be transmitted;
Synchronous data transmission device. A receiving antenna that receives the carrier from the identified satellite;
A receiving side carrier wave detecting unit for detecting a carrier wave from the carrier wave received by the receiving side antenna;
A receiving side clock signal extracting unit for extracting a clock signal from the carrier wave detected by the receiving side carrier wave detecting unit;
The clock signal extracted by the reception side clock signal extraction unit operates as a reception side reference clock signal, and the data transmitted in synchronization with the clock signal extracted from the carrier wave received from the specified satellite is sampled and reproduced. A sampling reproduction processing unit for processing;
A synchronous data receiving device.   2. The data transmission system according to claim 1, wherein the satellite is a GNSS satellite.

Images