JPH10107749A - Medium wave radio broadcast system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the medium wave radio broadcast system being a medium wave radio synchronization broadcast system in which phases of voice signals are synchronously with each other accurately even when a master station is making a broadcast and there are a plurality of slave stations. SOLUTION: A station A (master station) multiplexes a pilot signal on a voice broadcast program (voice signal) 1 and sends the multiplexed signal to a station B (slave station; satellite station) through, e.g. a public telephone line 12-1. Simultaneously the voice signal is sent back to the station A through other public telephone line 12-2 and the phase of the sent-back voice signal 5-2 is compared with that of the original voice signal 5-1 based on a pilot signal and a voice delay unit 11-2 at the station B is controlled via a control processing unit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medium-wave radio broadcasting system, and more particularly to a medium-wave radio broadcasting system for performing synchronous broadcasting.

[0002]

2. Description of the Related Art In order to expand the service area of a medium-wave radio broadcast, another station (satellite station) may be provided in a hearing-impaired area in addition to its own broadcaster. The own station and the satellite station may broadcast at the same frequency, for example, and in a boundary area, signals received from both stations are mixed, so that audio distortion occurs. In order to reduce the audio distortion, it is necessary that the carrier frequencies broadcast from both stations are the same and that the audio signal phases when broadcasting from both stations are matched. A broadcast system that matches the carrier frequency broadcast from both stations with the phase of the audio signal is called a medium-wave radio synchronous broadcast.

[0003] As a conventional medium-wave radio synchronous broadcasting system, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 15730/1990. FIG. 2 shows an example of a medium-wave radio synchronous broadcasting system described in Japanese Patent Laid-Open No. 15730/1990.

In FIG. 2, reference numeral 2-1 denotes a transmitter of station A (own station) for transmitting at the same carrier frequency, reference numeral 10-1 denotes its transmitting antenna, reference numeral 22 denotes a modulated voice signal of station A,
Reference numeral 23 denotes a modulated voice signal input to the transmitter 2-2 of the station B (satellite station), reference numeral 12 denotes a circuit network for transmitting the modulated voice signal to the transmitter 2-2 of the station B, and reference numeral 20 denotes a transmitting antenna 10- of the station B. 2, a receiving antenna as a receiving device for receiving a transmission wave transmitted from 2, a receiver 21 as a receiving device, 11-1 a variable audio delay line capable of varying the delay time of the modulated audio signal 22, and 8 a receiver The phase comparator 9 corrects the phase of the demodulated audio output 21 and the modulated audio output which is the output of the variable audio delay line 11-1. The phase comparator 9 reads the output voltage of the phase comparator 8 and -1
Is a controller as a correction device that outputs a control signal for variably operating. 24 is a variable audio delay line 11 from the controller 9
The above control signal to -1 is shown.

Next, the operation will be described. Now, while the broadcasting of the station A is stopped, the receiving antenna 20 can receive the transmission wave transmitted from the transmitting antenna 10-2 of the station B. Now, when a modulated audio signal having a reference frequency (for example, 1 kHz) is transmitted as the modulated audio signals 22 and 23 to the stations A and B, the transmitter 2-2 of the station B transmits the modulated audio signal 23 at 1 kHz. , And the output of the receiver 21 is 1 k obtained by demodulating the modulated wave transmitted from the B station.
Hz signal is obtained. The 1 kHz demodulated signal is input to the phase comparator 8.

On the other hand, the modulated audio signal 22 at the station A is input to the variable audio delay line 11-1, and then to the phase comparator 8. Therefore, as the output of the phase comparator 8, a voltage corresponding to the phase difference between the two is obtained. In the controller 9,
This output voltage is read, the delay time of the variable audio delay line 11-1 is controlled so that the phase difference between them is constant, and the control value is stored.

After the broadcast of the station A starts, the receiver 21 cannot receive the transmission wave of the station B. Therefore, the controller 9 determines the delay time of the variable audio delay line 11-1 based on the stored control value. Control.

However, this control value includes the transmitter 2 of the station A.
-1 is not included, so that the transmitter 2
The variable audio delay line 11-1 is controlled by the control value obtained by correcting the delay time of -1 during the broadcasting of the station A.

As described above, every time the broadcast is stopped, the correction device including the phase comparator 8 and the controller 9 performs the re-correction. Therefore, the fluctuation of the delay time when the circuit network 12 is changed is permanently corrected. It can be performed reliably.

[0010]

SUMMARY OF THE INVENTION FIG.
In the medium-wave radio synchronous broadcasting system described in Japanese Patent No. 15730, unless the broadcasting of the station A (own station; master station) is stopped, the station is located near the station A and the electric field strength of the transmission wave of the station A is high. Cannot receive the transmission wave of the B station (slave station; satellite station) and cannot obtain the control signal 24 of the variable audio delay line 11-1. There is.

In this case, the variable audio delay line 11-1
Is located on the master station (station A) side, there is a problem that this cannot be applied when there are a plurality of satellite stations (station B; slave stations).

An object of the present invention is to provide a medium-wave radio broadcast system which can accurately synchronize the phase of an audio signal even when the main station is broadcasting or when there are a plurality of satellite stations. That is.

[0013]

According to the present invention, a pilot signal is superimposed on a broadcast audio signal of a master station, which is a medium-wave radio broadcast station, and transmitted as a first audio signal to a slave station through a first transmission path. The slave station generates the same carrier as the master station based on the pilot signal, and the slave station obtains the same carrier as the master station from the first audio signal obtained through the first transmission path. A medium-wave radio synchronous broadcasting system for modulating and broadcasting with a signal excluding the pilot signal,
First delay means inserted into the input section of the master station transmitter to provide a fixed delay to the broadcast audio signal; and inserted into the input section of the slave station transmitter to provide a variable delay to the broadcast audio signal Second delay means, means for sending back the first audio signal obtained through the first transmission path in the slave station to the master station side as a second audio signal through a second transmission path, Audio signal delay control means for controlling the second delay means by comparing the phase of the first and second audio signals on the side and measuring the amount of delay of the first audio signal by the first transmission line And a medium-wave radio broadcasting system characterized by including the following.

The operation of the present invention is as follows. The station A (master station) multiplexes the pilot signal with the audio broadcasting program (audio signal), and transmits the multiplexed signal to the station B (slave station; satellite station) through, for example, a public telephone line. At the same time, the voice signal is sent back to the A station through another public telephone line, the returned voice signal and the original voice signal are compared in phase with respect to the pilot signal, and the voice delay at the B station is transmitted via the control processing unit. Control the unit.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a medium-wave radio broadcasting system according to the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In addition, overlapping description is omitted.

As shown in FIG. 1, an audio delay unit 11-1 for giving a fixed delay amount (t1) to a broadcast program (audio signal) 1 modulates and amplifies the delayed audio signal 1 and transmits the amplified signal to a transmission antenna 10-. Transmitter (Tx) broadcasting via 1
2-1, a pilot signal generator 4 for generating a pilot signal (for example, 10 to 20 kHz), a carrier wave generator 6 for generating a carrier (in the medium wave band) by multiplying the pilot signal and supplying the carrier to the transmitter 2-1 -1, station A (own station; master station), B
Even if both stations (slave stations; satellite stations) are broadcasting,
To be able to adjust the audio delay amount on the B station side 11-2,
The pilot signal multiplexing unit 3 for superimposing the pilot signal on the audio signal 1 and the audio signal 5-1 transmitted to the B station side in the program transmission path 12-1 are transmitted to another transmission path 12-2.
To the A station side through
2 and the original audio signal 5-1 for comparing the phase of the superimposed pilot signal, and a control for controlling the audio delay unit 11-2 on the B station side based on the output voltage of the comparison circuit 8. The control processing unit 9 that generates the signal 24
The broadcasting device on the station A side is configured.

A program separation unit 7 for separating the audio signal 5-1 transmitted to the B station side through the program transmission line 12-1 into a pilot signal and a program (voice) signal, and multiplies the separated pilot signal. , A carrier wave generator 6-1 that generates a carrier having the same frequency as the output of the carrier wave generator 6-1 and supplies the carrier to the transmitter 2-2.
A variable delay (t2) is given to the separated voice signal, a voice delay unit 11-2 to be supplied to a transmitter 2-2, and a carrier wave are amplitude-modulated by a voice signal output from the voice delay unit 11-2, and transmitted. The transmitter 2-2 for broadcasting via the antenna 10-2 constitutes a broadcasting device on the B station side.

The operation of the embodiment of the present invention will be described. A broadcast program (audio signal) 1 transmitted from a music hall (not shown) is transmitted to a transmitter 2 via an audio delay unit 11-1 of the A station. -1 and at the same time, the signal is input to the pilot signal multiplexing unit 3 and superimposed with the pilot signal from the pilot signal generator 4 to the station B as the audio signal 5-1 via the program transmission line 12-1. Transmitted.

The audio signal 5-1 transmitted to the station B is input to the program separation unit 7 and, at the same time, is sent back to the station A as an audio signal 5-2 via the program transmission line 12-2. The signal 8 is input to the circuit 8 together with the audio signal 5-1, and the phases of the pilot signals of the two signals 5-1 and 5-1 are compared.

As the program transmission paths 12-1 and 12-2,
If a public telephone line is used, the transmission bandwidth is narrow and the delay time is large. The output of the comparison circuit 8 corresponds to the delay time of the program transmission paths 12-1 and 12-2. Since the program transmission lines 12-1 and 2 have exactly the same delay time, the output of the comparison circuit 8 is proportional to twice the delay time of the program transmission line 12-1 between the A and B stations.

Since the phase of the audio signal broadcasted by the station B is delayed from the phase of the audio signal broadcasted by the station A by almost the delay time of the program transmission path 12-1, a fixed delay ( An audio delay unit 11-1 that provides t1) is inserted. By selecting t1> t2 as compared with the variable delay amount (t2) of the audio delay unit 11-2 on the B station side, the variable delay amount (t2) of the audio delay unit 11-2 is controlled by the control signal 2
4, the phases of audio signals (programs) broadcast from stations A and B can be matched.

Since the control signal 24 needs to be transmitted from the station A to the station B, it is appropriate to be in the form of a digital signal.

Although a plurality of pilot signals may be required depending on the system, in the embodiment of the present invention, a single sine wave of, for example, 10 to 20 kHz is sufficient.

[0025]

As described above, according to the present invention, an audio signal is sent back from a slave station to a master station using a transmission line such as a public line, and the delay amount of the audio signal on the transmission line is measured. By controlling the audio delay unit of the master station,
Even when the slave station is in the broadcasting operation, the medium-wave radio synchronous broadcasting is always normally maintained in response to the change of the transmission path.

Also, since the voice delay unit to be controlled is inserted on the slave station side, there is an effect that even if a plurality of slave stations exist, it can be handled.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of an example of a conventional medium-wave radio synchronous broadcasting system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Broadcast program 2-1 and 2 transmitter 3 Pilot signal multiplexing unit 4 Pilot signal generator 5-1 and 2 audio signal 6-1 and 2 Carrier generator 7 Program separation unit 8 Comparison circuit 9 Control processing unit 10-1 2 Transmission antenna 11-1, Audio delay unit 12-1, Program transmission path 24 Control signal

Claims (5)

[Claims] 1. A pilot signal is superimposed on a broadcast audio signal of a master station, which is a medium-wave radio broadcast station, and is sent as a first audio signal to a slave station through a first transmission path. Generates the same carrier as the main station,
A medium-wave radio synchronous broadcasting system in which the slave station modulates the same carrier as the master station with a signal obtained by removing the pilot signal from the first audio signal obtained through the first transmission path and broadcasts. A first delay unit inserted into the input unit of the transmitter of the master station to give a fixed delay to the broadcast audio signal; and a variable delay inserted into the input unit of the transmitter of the slave station to provide a variable delay to the broadcast audio signal. Second delay means for giving, a means for sending back the first audio signal obtained through the first transmission path in the slave station to the master station side as a second audio signal through a second transmission path, An audio signal delay control for controlling the second delay means by measuring the delay amount of the first audio signal by the first transmission line by comparing the phases of the first and second audio signals at the station side; And a medium wave. Oh broadcasting system. 2. The medium-wave radio broadcasting system according to claim 1, wherein a delay amount of said first delay means is larger than a delay amount of said second delay means. 3. The medium-wave radio broadcasting system according to claim 1, wherein said first and second transmission lines are the same kind of public telephone lines. 4. A medium-wave radio broadcasting system according to claim 1, wherein said second delay means is controlled by a control signal in the form of a digital signal. 5. The medium-wave radio broadcasting system according to claim 1, wherein said pilot signal is one kind of sine wave.