JP2016116038A - Transmitter and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter and a transmission method capable of preventing mutual interference among broadcast waves in a boundary region of plural broadcast service areas even when the broadcast is made using identical frequency from plural transmitter stations.SOLUTION: The transmitter includes: a signal extraction section; a clock generation section; and a transmission section. The signal extraction section extracts a synchronous signal which has a phase synchronous with the broadcast signal from the input broadcast signal. The clock generation section generates a clock signal which is synchronous with the synchronous signal and has the predetermined frequency from a reference signal which has the synchronous signal and a predetermined frequency. The transmission section performs a modulation processing on the broadcast signal based on the clock signal and transmits the signal after the modulation processing.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a transmission apparatus and a transmission method.

  In FM (Frequency Modulation) broadcasting, the same program may be broadcast from a plurality of transmitting stations in order to expand the broadcasting service area. In such a broadcasting mode, when the same program is broadcast from each transmitting station at the same frequency, the broadcast waves transmitted from each transmitting station interfere with each other in the vicinity of the boundary area of the broadcasting service area of the plurality of transmitting stations, There may be cases where they cancel each other due to the difference in phase. In this case, since it is difficult to receive broadcasts in the vicinity of the boundary region, broadcasting is not performed at the same frequency from each transmitting station.

JP 7-162382 A JP-A-8-8765 JP 2002-101055 A

  A problem to be solved by the present invention is to provide a transmission apparatus and a transmission method capable of suppressing mutual interference of broadcast waves in a boundary area between a plurality of broadcast service areas even when broadcast from a plurality of transmission stations at the same frequency. It is to be.

  The transmission apparatus according to the embodiment includes a signal extraction unit, a clock generation unit, and a transmission unit. The signal extraction unit extracts a synchronization signal having a phase synchronized with the broadcast signal from the input broadcast signal. The clock generator generates a clock signal that is synchronized with the synchronization signal and has the predetermined frequency from the synchronization signal and a reference signal having a predetermined frequency. The transmission unit performs modulation processing of the broadcast signal based on the clock signal, and transmits the signal subjected to the modulation processing.

FIG. 2 is a block diagram illustrating a configuration example of a transmission apparatus according to the first embodiment. FIG. 5 is a timing chart for explaining an operation example of the transmission apparatus according to the first embodiment. The block diagram which shows the structural example of the transmitter of 2nd Embodiment. The timing diagram for demonstrating the operation example of the transmitter of 2nd Embodiment.

Hereinafter, a transmission apparatus according to an embodiment will be described with reference to the drawings.
(First embodiment)
With reference to FIG. 1, the structural example of the transmitter 10 of 1st Embodiment is demonstrated.
FIG. 1 is a block diagram illustrating a configuration example of the transmission device 10 according to the first embodiment.
The transmission device 10 includes a reception unit 11, a transmission unit 12, and a clock generation unit 13. Among these, the receiving part 11 is an element for decoding the input broadcast signal DBS. The broadcast signal DBS is a digital audio signal for FM broadcast of AES (Audio Engineering Society) standard, and is an encoded signal. However, the present invention is not limited to this example, and the broadcast signal DBS can be an arbitrary format signal. In the first embodiment, the receiving unit 11 extracts a synchronization signal SYC having a phase synchronized with the clock of the broadcast signal DBS and a reference signal REF having a predetermined reference frequency from the input broadcast signal DBS. It has a function as a part. The reference signal REF is a signal extracted from the broadcast signal DBS by detecting a change point of the data signal included in the broadcast signal DBS, and details thereof will be described later. The receiving unit 11 outputs a stereo broadcast signal DST composed of a right channel (R) signal and a left channel (L) signal obtained by decoding the broadcast signal DBS.

  The transmission unit 12 is an element for performing a modulation process on the stereo broadcast signal DST based on a clock signal φ described later output from the clock generation unit 13 and transmitting the broadcast signal subjected to the modulation process. . The transmission unit 12 includes a stereo modulation unit 121, an FM modulation unit 122, an up converter 123, an amplifier 124, a band pass filter 125, and an antenna 126. Among these, the stereo modulation unit 121 is an element that generates a stereo composite signal from the sum / difference signal of the right channel and the left channel of the stereo broadcast signal DST input from the reception unit 11, for example.

  The FM modulation unit is an element for generating an FM modulated signal by FM modulating a predetermined carrier wave using the stereo composite signal. The up-converter 123 is an element for converting the frequency of the FM modulation signal to a designated transmission frequency. The amplifier 124 is an element for power-amplifying the frequency-modulated FM modulated signal. The antenna 126 is an element for radiating the power-amplified broadcast signal as a broadcast wave (radio wave) to space.

  The clock generation unit 13 has a phase synchronized with the synchronization signal SYC from the synchronization signal SYC and the reference signal REF extracted by the reception unit 11 and has a predetermined reference frequency of the reference signal REF. It is an element for generating. In the first embodiment, the reference signal REF extracted by the reception unit 11 is input to the clock generation unit 13, but the reference signal REF input to the clock generation unit 13 is not necessarily the reception unit 11. It is not necessary that the signal is extracted by the above, and any signal can be used as long as it can be used for modulation by the transmission unit 12.

  The clock generation unit 13 includes a PLL (Phase Locked Loop) circuit 131, a voltage controlled oscillator (VCXO) 132, and a clock synchronization unit 133. Among these, the PLL circuit 131 is input to the voltage controlled oscillator 132 so that the phase difference between the reference signal REF input from the receiving unit 11 and the reference clock signal φR output from the voltage controlled oscillator 132 becomes small. This is an element for adjusting the voltage level of the control voltage signal CR to be controlled. The voltage controlled oscillator 132 is an element for generating a reference clock signal φR having a frequency corresponding to the signal level of the control voltage signal CR adjusted by the PLL circuit 131.

  The clock synchronization unit 133 is an element for generating the clock signal φ by synchronizing the phase of the reference clock signal φR input from the voltage controlled oscillator 132 with the synchronization signal SYC input from the reception unit 11. The clock signal φ has a reference frequency of the reference clock signal φR and a phase synchronized with the synchronization signal SYC. The clock signal φ is supplied to the stereo modulation unit 121, the FM modulation unit 122, and the up-converter 123 that constitute the transmission unit 12, and is used for modulation processing performed in the transmission unit 12.

Next, an operation example of the transmission apparatus 10 according to the first embodiment will be described with reference to FIG.
FIG. 2 is a timing diagram for explaining an operation example of the transmission apparatus 10 according to the first embodiment. As illustrated in the top of FIG. 2, a broadcast signal DBS, which is an AES standard digital audio signal, is composed of a left-channel subframe SF (L) and a right-channel subframe SF (R) alternately arranged in time series. ). One frame is composed of one left channel subframe SF (L) and one right channel subframe SF (R), and one block is composed of 192 frames FL0 to FL191. Each subframe is composed of, for example, 32-bit time slots arranged at a predetermined cycle (fixed cycle). The broadcast signal DBS includes a block frame signal (not shown) that defines the start position of each block BK.

  The receiving unit 11 decodes the encoded broadcast signal DBS to generate and output a stereo broadcast signal DST (L, R) having a data format illustrated in the uppermost stage of FIG. At this time, for example, the reception unit 11 extracts and outputs a block frame signal that defines the start position of the block BK as the synchronization signal SYC. Therefore, the synchronization signal SYC is a signal having the period T of one block BK as one period, and is a signal having a frequency of, for example, 250 Hz.

  In addition, the receiving unit 11 detects, for example, a change point of a data signal of one frame (64 bits) having a predetermined period (constant period) included in the broadcast signal DBS, so that the reference signal REF having a predetermined frequency is detected from the broadcast signal DBS. Is extracted and output. Therefore, the reference signal REF is, for example, a signal with one frame as one cycle, and is a signal having a predetermined frequency of, for example, 12.288 MHz (= 48 kHz × 256). The predetermined frequency of the reference signal REF corresponds to a predetermined cycle of the data signal included in the broadcast signal DBS. However, the present invention is not limited to this example, and the receiving unit 11 detects the change point of the data signal (bit signal) in the time slot of the predetermined period (constant period) of each subframe included in the broadcast signal DBS. REF may be extracted.

  The transmission unit 12 modulates and transmits the stereo broadcast signal DST input from the reception unit 11. When the stereo broadcast signal DST is modulated, the transmission unit 12 uses the clock signal φ generated by the clock generation unit 13 described below in the stereo modulation unit 121, the FM modulation unit 122, and the up-converter 123.

  The clock generator 13 generates a clock signal φ using the synchronization signal SYC and the reference signal REF input from the receiver 11 and supplies the clock signal φ to the transmitter 12. Specifically, the PLL circuit 131 controls the control voltage signal so that the phase difference between the reference signal REF and the reference clock signal φR becomes small in the feedback loop formed by the PLL circuit 131 and the voltage controlled oscillator 132. The voltage level of CR is changed. The voltage controlled oscillator 132 generates a reference clock signal φR having a frequency corresponding to the voltage level of the control voltage signal CR. Thereby, a reference clock signal φR synchronized with the reference signal REF is obtained. The reference clock signal φR is supplied to the clock synchronization unit 133.

  The clock synchronization unit 133 matches the phase of the reference clock signal φR with the phase of the synchronization signal SYC. For example, the clock synchronization unit 133 delays the reference clock signal φR so that the phase difference between the synchronization signal SYC and the reference clock signal φR becomes small. Then, the clock synchronization unit 133 outputs a signal obtained by delaying the reference clock signal φR as the clock signal φ.

  Therefore, the phase of the clock signal φ is synchronized with the start position of the block BK defined by the block frame signal that is the original signal of the synchronization signal SYC, and the frequency of the clock signal φ is the frequency of the reference signal REF that provides the reference clock signal φR. It matches the predetermined frequency, that is, the frequency of the frame included in the stereo broadcast signal DST. That is, the clock signal φ is a clock signal based on the clock of the AES standard broadcast signal DBS.

  The stereo modulation unit 121, the FM modulation unit 122, and the up-converter 123 of the transmission unit 12 perform modulation processing of the stereo broadcast signal DST input from the reception unit 11 based on the clock signal φ generated by the clock generation unit 13. To do. The modulation processing by the transmission unit 12 is performed at a timing synchronized with the frame of the broadcast signal DBS. The modulated broadcast signal is transmitted from the antenna 126 to the broadcast service area at a timing synchronized with the frame of the broadcast signal DBS.

  As described above, the transmission device 10 according to the first embodiment generates the clock signal φ from the synchronization signal SYC extracted from the broadcast signal DBS and the reference signal REF. Therefore, the phase and frequency of the clock signal φ are set with reference to the clock of the broadcast signal DBS, and the output timing and frequency of the broadcast wave transmitted from the transmission device 10 are set with reference to the clock of the broadcast signal DBS. .

  Therefore, for example, when the SFN (Single Frequency Network) is constructed by distributing a plurality of transmitters 10 in order to expand the broadcast service area, each of the plurality of transmitters 10 to which the broadcast signal DBS is commonly input is provided. When the delay amount of the signal processing is combined, the phases of the clock signals φ in the plurality of transmission apparatuses 10 match each other on the basis of the clock of the single broadcast signal DBS, and are thus output from the plurality of transmission apparatuses 10 respectively. The phases of the broadcast waves are also the same. In addition, the frequencies of the clock signals φ in the plurality of transmission devices 10 also match each other, and thereby the frequencies of the broadcast waves output from each of the plurality of transmission devices 10 also match each other. For this reason, the output timings of the broadcast waves output from the plurality of transmission apparatuses 10 are aligned, and the phases and frequencies of the broadcast waves output from the transmission apparatuses 10 are aligned.

  Therefore, according to the first embodiment, it is possible to reduce the mutual interference of broadcast waves in the boundary areas of the broadcast service areas of the plurality of transmission apparatuses 10 that are distributed. Therefore, it is possible to receive a broadcast with less fading, noise, and the like due to the mutual interference of broadcast waves in all areas of the plurality of broadcast service areas corresponding to the plurality of transmission apparatuses 10. Therefore, in order to avoid mutual interference in the vicinity of the boundary area of the broadcast service area, it is not necessary to change the transmission frequency for each transmission device, and the frequency can be effectively used.

  In the first embodiment, the receiving unit 11 extracts the synchronization signal SYC from the AES standard broadcast signal DBS. However, the synchronization signal SYC is not limited to this example, and may be input to a plurality of transmission apparatuses 10 in common. An arbitrary signal can be used as the synchronization signal SYC as long as the signal is compatible with the modulation processing in each transmission apparatus. The same applies to the reference signal REF.

(Second Embodiment)
Next, a second embodiment will be described.
FIG. 3 is a block diagram illustrating a configuration example of the transmission device 20 according to the second embodiment.
The transmission device 20 includes a clock generation unit 23 in place of the clock generation unit 13 in the configuration of the transmission device 10 of the first embodiment illustrated in FIG. 1. The clock generation unit 23 basically has the same configuration as that of the clock generation unit 13 of the first embodiment. However, the reference signal REF input to the PLL circuit 131 is a GPS (Global Positioning System). It is a GPS signal received from a satellite (not shown) satellite. The frequency of the GPS signal is, for example, 10 MHz. In the example of FIG. 4, the waveform of the reference signal REF, which is a GPS signal, is schematically shown. Others are the same as in the first embodiment.

  FIG. 4 is a timing diagram for explaining an operation example of the transmission apparatus 20 according to the second embodiment. In the second embodiment, the clock generator 23 generates the clock signal φ using the synchronization signal SYC input from the receiver 11 and the reference signal REF that is a GPS signal. Specifically, the PLL circuit 131 changes the voltage level of the control voltage signal CR so that the phase difference between the reference signal REF (GPS signal) and the reference clock signal φR becomes small. Then, the voltage controlled oscillator 132 generates a reference clock signal φR having a frequency corresponding to the voltage level of the control voltage signal CR. Thereby, the reference clock signal φR synchronized with the GPS signal is obtained.

  As in the first embodiment, the clock synchronization unit 133 generates the clock signal φ by matching the phase of the reference clock signal φR with the phase of the synchronization signal SYC. The phase of the clock signal φ is synchronized with the start position of the block BK defined by the block frame signal that is the original signal of the synchronization signal SYC. On the other hand, since the reference clock signal φR in the second embodiment is a signal synchronized with the GPS signal, the frequency of the clock signal φ is the frequency of the GPS signal (for example, 10 MHz). Therefore, the clock signal φ is not synchronized with the clock of the broadcast signal DBS.

  However, since the clock synchronization unit 133 matches the phase of the clock signal φ with the phase of the synchronization signal SYC, the clock signal φ is synchronized with the frame of the broadcast signal DBS. Therefore, also in the second embodiment, the clock signal φ is a clock signal based on the clock of the AES standard broadcast signal DBS. Therefore, as in the first embodiment, the modulation processing by the transmission unit 12 is performed at a timing synchronized with the frame of the broadcast signal DBS, and the modulated broadcast signal is transmitted from the antenna 126 to the frame of the broadcast signal DBS. It is transmitted to the broadcast service area at the timing synchronized with.

  In the second embodiment, as described above, the transmission device 20 outputs a broadcast wave at a timing synchronized with the frame of the broadcast signal DBS. Therefore, a plurality of transmission devices 20 are distributed in order to expand the broadcast service area. In this case, similarly to the first embodiment, it is possible to obtain the effect of reducing the mutual interference of the broadcast waves in the boundary area of the broadcast service area of each transmission device.

  The operation of the transmission apparatus 10 according to the above-described embodiment can also be expressed as a transmission method. In this case, the transmission method synchronizes with the synchronization signal from the first stage of extracting a synchronization signal having a phase synchronized with the input broadcast signal, the synchronization signal and a reference signal having a predetermined frequency, and A second step of generating a clock signal having the predetermined frequency; and a third step of performing a modulation process on the broadcast signal based on the clock signal and transmitting the signal subjected to the modulation process. Here, the content of the process in the first stage is the same as the content of the operation of the receiving unit 11. The contents of the processing in the second stage are the same as the contents of the operation of the clock generator 13 or the clock generator 23. Further, the content of the processing in the third stage is the same as the content of the operation of the transmission unit 12.

  According to the transmission apparatus or the transmission method of at least one embodiment described above, even if broadcasting is performed from a plurality of transmitting stations at the same frequency, it is possible to suppress the mutual interference of broadcast waves in the boundary areas of the plurality of broadcasting service areas. it can.

  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 embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Transmission apparatus, 11 ... Reception part, 12 ... Transmission part, 13, 23 ... Clock generation part, 121 ... Stereo modulation part, 122 ... FM modulation part, 123 ... Up converter, 124 ... Amplifier, 125 ... Band pass filter, 126 ... antenna, 131 ... PLL circuit, 132 ... voltage controlled oscillator.

Claims (8)

A signal extraction unit that extracts a synchronization signal having a phase synchronized with the broadcast signal from an input broadcast signal;
A clock generator that generates a clock signal that is synchronized with the synchronization signal and has the predetermined frequency from the synchronization signal and a reference signal having a predetermined frequency;
A transmitter that performs modulation processing of the broadcast signal based on the clock signal and transmits the signal subjected to the modulation processing;
A transmission device comprising:   The transmission apparatus according to claim 1, wherein the reference signal is a signal extracted from the broadcast signal by detecting a change point of a data signal having a predetermined period included in the broadcast signal.   The transmission apparatus according to claim 1, wherein the reference signal is a GPS (Global Positioning System) signal. The broadcast signal is an AES (Advanced Encryption Standars) standard signal,
The transmission device according to claim 1, wherein the synchronization signal is a signal that defines a start position of a block included in the broadcast signal. Extracting a synchronization signal having a phase synchronized with an input broadcast signal;
Generating a clock signal having the predetermined frequency in synchronization with the synchronous signal from the synchronous signal and a reference signal having the predetermined frequency;
Performing a modulation process of the broadcast signal based on the clock signal, and transmitting the signal subjected to the modulation process;
Including sending method.   6. The transmission method according to claim 5, wherein the reference signal is a signal extracted from the broadcast signal by detecting a change point of a data signal having a predetermined cycle included in the broadcast signal.   The transmission method according to claim 5, wherein the reference signal is a GPS (Global Positioning System) signal. The broadcast signal is an AES (Advanced Encryption Standars) standard signal,
The transmission method according to claim 5, wherein the synchronization signal is a signal that defines a start position of a block included in the broadcast signal.

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