WO2022239608A1

WO2022239608A1 - Transmission device

Info

Publication number: WO2022239608A1
Application number: PCT/JP2022/018110
Authority: WO
Inventors: 敬彦鈴木
Original assignee: 株式会社日立国際電気
Priority date: 2021-05-10
Filing date: 2022-04-19
Publication date: 2022-11-17
Also published as: JPWO2022239608A1

Abstract

[Problem]　To obtain a transmission device having a simple structure which has redundancy against failure of an FM modulator and does not require a switching operation.　[Solution]　A synchronous first modulator 11 and a synchronous second modulator 12 that are independent from one another and FM-modulate a carrier wave using a common audio signal are used, FM1 is generated by the synchronous first modulator 11, and FM2 is generated by the synchronous second modulator 12. Although the first synchronous modulator 11 and the second synchronous modulator 12 operate independently, the operations of said modulators are synchronized by a common reference signal being input. In the transmission device 1, the FM1 and FM2 are combined by a combiner 13 and output as an output signal. Therefore, no switching operation is performed in the transmission device 1, and thus the output signal is not interrupted at the time of switching.

Description

transmitter

The present invention relates to an FM transmission apparatus having redundancy against modulator abnormalities.

　Transmission devices for broadcasting are designed to be redundant in order to prevent the suspension of broadcasting due to sudden events such as device failure. For example, two transmitters that emit different RF signals are used, one of which is used normally (active system) and the other is used as a spare transmitter (standby system) when the active system fails. A configuration is known in which a switch is used to switch between the output of the active system transmission unit and the output of the standby system transmission unit according to the demand. However, since it takes a certain amount of time for the switching operation to be performed by the switch, there is a period during which the output is interrupted during this switching operation. In addition, since the requirements for the reliability and characteristics of the switch used for this purpose have become stricter, the switch has become more expensive.

In Patent Document 1, the two transmission units are not divided into two, the active system and the standby system, as described above, but the RF signal that is the output of each is divided into two, and the RF signal after distribution is divided into two. A transmission device is described that combines and outputs after changing the combination according to the situation. According to this configuration, interruption of the signal at the time of switching is suppressed. However, even in this case, the operation of switching the combination is performed, so the use of the switcher is essential. Also, the two RF signals must be synthesized while their frequencies and phases are matched.

On the other hand, in Patent Document 2, by providing a phase controller, the frequency and phase of the RF signal output by the transmission unit of the standby system match the frequency and phase of the RF signal output by the transmission unit of the active system. A technique is described in which the matching RF signals are always combined and output. In this case, the RF signals of the active system and the standby system and the combined signal are the same except for the intensity, and even if the active system fails and the RF signal is lost, the combined signal will be the RF signal of the standby system. signal, and the desired RF signal is obtained without any special switching action. Therefore, no interruption of the signal occurs during the switching operation.

JP-A-2001-326579 Japanese Patent Application Laid-Open No. 2021-34970

In a transmitter for FM broadcasting, the output of the FM modulator is input to the power amplifier in the subsequent stage and emitted from the transmitter as an RF signal as described above. Since it is necessary to suppress the interruption of broadcasting due to the failure of the FM modulator, it has been desired to provide similar redundancy for the failure of the FM modulator.

In this case, two FM modulators (active system, standby system) are further provided for each transmission unit as described in Patent Documents 1 and 2, and the operation of switching between these FM modulators is performed (switching It has become necessary to take out outputs from two FM modulators without switching RF signals as in the technique described in Patent Document 2).

However, in this case, if a switch is used, the number of switches increases, which makes the transmitter expensive, or causes more problems associated with switching. Alternatively, if a switch is not used as in the technique described in Patent Document 2, although there is no problem associated with switching, the configuration becomes complicated and the cost of the transmission apparatus increases.

For this reason, a transmitter with a simple structure that has redundancy against failure of the FM modulator and does not require a switching operation has been desired.

The present invention has been made in view of such circumstances, and aims to solve the above problems.

The present invention is a transmission apparatus using an output signal obtained by performing FM modulation of a carrier wave with an audio signal, wherein the common audio signal is synchronized by inputting a common reference signal. a synchronous first modulating unit and a synchronous second modulating unit that perform FM modulation of the common carrier wave, and a first modulated signal that is the output of the synchronous first modulating unit and the output of the synchronous second modulating unit and a synthesizing unit for synthesizing the second modulated signal and outputting it as the output signal.
At this time, an output signal adjusting section may be provided for controlling the first synchronous modulating section and the second synchronous modulating section to adjust the intensity of the first modulating signal and the second modulating signal.
Further, the output signal adjustment unit adjusts the output level to a predetermined range based on the detected output level of the output signal or by external control, the synchronous first modulation unit, the A synchronous second modulation unit may be controlled.
Further, the audio signal synthesized with a pilot signal in a stereo system is input to the first synchronous modulation section and the second synchronous modulation section, and the pilot signal and the second modulation in the first modulated signal are input to the first synchronous modulation section and the second synchronous modulation section. a first modulated signal monitoring unit and a second modulated signal monitoring unit respectively recognizing the presence or absence of the pilot signal in a signal, wherein either the first modulated signal or the second modulated signal is The one output may be stopped when the pilot signal is not recognized.

According to the present invention, it is possible to obtain a transmission device with a simple structure that has redundancy against failure of the FM modulator and does not require switching operation.

FIG. 2 is a diagram showing a partial configuration of a transmission device according to an embodiment; FIG. FIG. 3 is a diagram showing a partial configuration of a conventional transmission device;

Next, embodiments for carrying out the present invention will be specifically described with reference to the drawings. A transmitting apparatus according to an embodiment of the present invention is used for stereo FM broadcasting. Since this transmitter has two FM modulators, it has redundancy against malfunction of the FM modulators, but there is no switching operation that would cause an interruption of the output signal. FIG. 1 is a diagram showing the configuration of this transmission device 1. As shown in FIG.

FIG. 1 partially shows only the configuration up to outputting an FM signal FM-modulated with a stereo audio signal in this transmitting apparatus 1 . For this reason, the configuration of FIG. 1 corresponds to, for example, a portion for outputting an FM-modulated signal in the transmitting apparatus described in Patent Documents 1 and 2, and can be applied to both active and standby transmitting apparatuses. Become.

Here, a synchronous first modulator (synchronous first modulator) 11 and a synchronous second modulator (synchronous second modulator) 12 that FM-modulate a carrier wave with a common audio signal are used. The first modulator 11 generates FM1 (first modulated signal), and the synchronous second modulator 12 generates FM2 (second modulated signal). Although the first synchronous modulator 11 and the second synchronous modulator 12 operate independently, their operations are synchronized by inputting a common reference signal.

In addition, in this transmitting device 1, FM1 and FM2 are combined by a combiner (combining unit) 13 and output as an output signal. Therefore, no switching operation is performed in this transmitting apparatus 1, so that the output signal is not interrupted at the time of switching.

The above operations and other components in FIG. 1 will be described in detail below. First, the first synchronous modulator 11 and the second synchronous modulator 12 operate in synchronization as described above. For this purpose the reference signal generator 20 in FIG. 1 is used. Specifically, for example, an Rb (rubidium) oscillator can be used as the reference signal generator 20 . As is well known, the Rb oscillator emits a 10 MHz signal and a 1 PPS (Pulse Per Second) signal, and these signals are used as a common reference signal for synchronization between relay stations located at different locations, for example, in synchronous broadcasting. used on occasion.

Therefore, by inputting this reference signal to the first synchronous modulator 11 and the second synchronous modulator 12, it is possible to synchronize FM1 and FM2 (make the phases the same). Such a synchronous modulator can be found at https://nitsuki.com, for example. com/products/fm_radio/fm_sync_broadcasting. html is described. Since FM1 and FM2 are modulated with a common audio signal, this essentially makes FM1 and FM2 the same signal. Since the input audio signal is a stereo audio signal, both FM1 and FM2 include a pilot signal added in the stereo system.

Therefore, the output signal obtained by combining FM1 and FM2 by the combiner 13 is the same signal as FM1 and FM2, differing only in output level (amplitude). At this time, FM1 is lost when the first synchronous modulator 11 fails, and FM2 is lost when the second synchronous modulator 12 fails. only fluctuates and the output signal becomes equal to FM2 in the former case and FM1 in the latter case. signal is obtained. Therefore, even if a failure occurs in the first synchronous modulator 11 or the second synchronous modulator 12, the output signal is not interrupted.

Although the reference signal generator 20 is a component of the transmitter 1 in FIG. 1, a similar reference signal can be input to the first synchronous modulator 11 and the second synchronous modulator 12. Insofar as the reference signal generator may be provided externally. A reference signal generator other than the Rb oscillator may be used as long as a reference signal for synchronizing the operations of the first synchronous modulator 11 and the second synchronous modulator 12 can be obtained.

In the operation described above, although the output signal is not lost when a failure occurs in the first synchronous modulator 11 and the second synchronous modulator 12, the output level (amplitude) fluctuates. However, in this case, fluctuations in the output level can also be suppressed. In FIG. 1, the output signal monitor 14 and the output signal adjuster 15 are used for this purpose.

The output signal monitor 14 extracts a part of the output signal output from the combiner 13 via the directional coupler 31 and detects the output level (amplitude) of the output signal. On the other hand, the output levels of FM1 and FM2 in the first synchronous modulator 11 and the second synchronous modulator 12 are output from the output signal adjustment section 15 to the first synchronous modulator 11 and the second synchronous modulator 12, respectively. It is adjustable by a directed output control signal. The output signal adjuster 15 can adjust the output levels of FM1 and FM2 based on the output level of the output signal detected by the output signal monitor 14 so that the output level of the output signal is within a certain range.

At this time, if the output signal adjustment unit 15 varies the output levels of FM1 and FM2 and recognizes the output level of the output signal, for example, even if the output level of one of FM1 and FM2 is abnormally low, the other By increasing the output level, it is possible to perform an operation in which the output level of the output signal is kept within a certain range. In this case, it takes a certain amount of time to complete this operation, and although the output level of the output signal fluctuates during this period, there is no interruption in the output signal during this period. Moreover, such adjustment of the output levels of FM1 and FM2 by the output signal adjusting section 15 may be performed from outside the transmitting apparatus 1 . At this time, for example, an output signal monitor may be provided outside.

When performing the operation to make the output level of the output signal constant in this way, the output signal adjustment unit 15 is operated to detect a failure in one of the first synchronous modulator 11 and the second synchronous modulator 12, for example. It is not necessary to recognize the effect directly. On the other hand, the first modulated signal monitoring unit 16 and the second modulated signal monitoring unit 17 in FIG. 1 directly recognize that a failure has occurred in the synchronous first modulator 11 and the synchronous second modulator 12. . This point will be described below.

As mentioned above, stereo audio signals are used here. As is well known, this audio signal actually uses a left signal (L) and a right signal (R), as described in Japanese Unexamined Patent Application Publication No. 2007-103986, for example. A composite signal is obtained by synthesizing the 19 kHz pilot signal. On the receiving side receiving this signal, L and R can be reproduced properly using this pilot signal. Therefore, under the precondition that the audio signal is of the stereo system, FM1 and FM2 always include this pilot signal.

Here, the first modulated signal monitoring unit 16 receives a portion of FM1 via a directional coupler 32, and the second modulated signal monitoring unit 17 receives a portion of FM2 via a directional coupler 33. Then, the first modulated signal monitoring section 16 and the second modulated signal monitoring section 17 check whether or not there is a pilot signal. If the pilot signal is not seen in FM1, it can be assumed that the first synchronous modulator 11 is not working properly, and similarly for FM2 (second synchronous modulator 12). In this way, when the pilot signal is not recognized in FM1, the first modulated signal monitoring unit 16, and when the pilot signal is not recognized in FM2, the second modulated signal monitoring unit 17 instructs the control unit 18. issue an alarm.

The control unit 18 outputs on/off control signals for controlling power supply (on/off) to the first synchronous modulator 11 and the second synchronous modulator 12 . Therefore, the control unit 18 operates the synchronous first modulator 11 when receiving an alarm from the first modulated signal monitoring unit 16, and operates the synchronous first modulator 11 when receiving an alarm from the second modulated signal monitoring unit 17. 2 modulators 12 can be turned off respectively.

Generally, when the synchronous first modulator 11 fails, FM1 is not emitted and the output signal is equal to FM2, and when the synchronous second modulator 12 fails, FM2 is not emitted. , the output signal will be equal to FM1. However, when the synchronous first modulator 11 and the synchronous second modulator 12 are out of order and improper outputs are generated as FM1 and FM2, the improper outputs become noise, resulting in an output signal. (FM1+FM2) is also not correct. Therefore, it is preferable to turn off the first synchronous modulator 11 when FM1 is not appropriate, and to turn off the second synchronous modulator 12 when FM2 is not appropriate. The control unit 18 can perform such operations.

In this operation, when the first synchronous modulator 11 and the second synchronous modulator 12 are turned off, the output level of the output signal fluctuates, but the output signal is not interrupted. Further, after the first synchronous modulator 11 and the second synchronous modulator 12 are turned off, the operation of the output signal adjusting section 15 as described above allows the output level of the output signal to be within the appropriate range. That is, by using the output signal adjusting section 15, the first modulated signal monitoring section 16, and the second modulated signal monitoring section 17 as described above, either the first synchronous modulator 11 or the second synchronous modulator 12 Even if a failure occurs in the output signal, the output level of the output signal can be maintained within a certain range without causing an interruption in the output signal.

FIG. 2 shows a partial configuration of a conventional transmission device 9 to be compared, corresponding to FIG. In this transmitting device 9, two independent ordinary FM modulators, a first modulator 91 and a second modulator 92, are used for FM modulation in the same manner as in the transmitting device 1 described above. By inputting a common audio signal, the carrier wave is FM-modulated to generate an FM signal (FM11 by the first modulator 91 and FM12 by the second modulator 92). Here, it is assumed that the first modulator 91 is used as the active system and the second modulator 92 is used as the standby system. Unlike the previous example, the first modulator 91 and the second modulator 92 do not operate synchronously.

Further, both the first modulator 91 and the second modulator 92 have a self-diagnostic function, and if an alarm is issued when an abnormality occurs, the control unit 93 responds to an external command or this alarm. Accordingly, the switch 94 can be controlled to select the output FM11 from the first modulator 91 and the output FM12 from the second modulator 92 and output to the power amplifier side. At this time, the unselected side of FM11 and FM12 is input to the terminator 95 and disappears. Here, FM11 is normally selected and FM12 is led to the terminator 95, and when the alarm is issued from the first modulator 91, the control section 93 selects the second modulator 92 (FM12) and is switched to the terminator 95.

In the configuration of FIG. 2, for example, when the control unit 93 recognizes an alarm from the first modulator 91 to switch the switch 94, in order to avoid the influence of noise, etc., the operation is actually performed for a certain period of time or longer. This switching action must be initiated after the continuation of the alarm is recognized. Also, in the operation of the switcher 94, it takes a certain amount of time from when the control unit 93 issues a switching command to when the switcher 94 issues a signal after switching. Therefore, when the switching operation was performed, the output signal was often interrupted.

On the other hand, in the transmitting apparatus 1, instead of the first modulator 91 and the second modulator 92, which are two independent ordinary FM modulators, the synchronous first modulator 11 and the synchronous second modulator By using the modulator 12 and using the combiner 13 instead of the switch 94, even if a failure occurs in either the synchronous first modulator 11 or the synchronous second modulator 12, the output There are no interruptions in the signal.

However, if a failure occurs in either the first synchronous modulator 11 or the second synchronous modulator 12, the output level of the output signal may fluctuate. In response to this, the output level can be kept within a certain range by using the output signal adjusting section 15, the first modulated signal monitoring section 16, the second modulated signal monitoring section 17, etc. as described above.

The present invention has been described above based on the embodiments. It should be understood by those skilled in the art that this embodiment is an example, and that various modifications can be made to the combination of each component, and that such modifications are within the scope of the present invention.

This application claims the benefit of priority based on Japanese Patent Application No. 2021-079438 filed on May 10, 2021, the entire disclosure of which is hereby incorporated by reference.

The present invention is suitable for obtaining a transmission device with a simple structure that has redundancy against FM modulator failure and does not require switching operation.

1, 9 Transmitting device 11 Synchronous first modulator (synchronous first modulating section) 12 Synchronous second modulator (synchronous second modulating section) 13 Synthesizer (synthesizing section) 14 Output signal monitor 15 Output signal adjustment Unit 16 First modulated signal monitor 17 Second modulated

signal monitor

18, 93 Control unit 20 Reference signal generators 31 to 33 Directional coupler 91 First modulator 92 Second modulator 94 Switcher 95 Terminator

Claims

A transmission device using an output signal obtained by performing FM modulation of a carrier wave with an audio signal,
a synchronous first modulating section and a synchronous second modulating section that perform FM modulation of the common carrier wave with the common audio signal in a state synchronized by inputting a common reference signal;
a synthesizing unit that synthesizes a first modulated signal that is the output of the first synchronous modulating unit and a second modulated signal that is the output of the second synchronous modulating unit and outputs the result as the output signal;
A transmitting device comprising:
2. An output signal adjusting section for controlling the first synchronous modulating section and the second synchronous modulating section to adjust the intensity of the first modulating signal and the second modulating signal. 2. The transmitting device according to .
The output signal adjustment unit adjusts the output level to a predetermined range based on the detected output level of the output signal or by external control, the synchronous first modulation unit, the synchronous 3. The transmitting apparatus according to claim 2, wherein the second modulating section is controlled.
inputting the stereo audio signal synthesized with the pilot signal to the first synchronous modulation unit and the second synchronous modulation unit;
a first modulated signal monitoring unit and a second modulated signal monitoring unit that respectively recognize the presence or absence of the pilot signal in the first modulated signal and the pilot signal in the second modulated signal,
2. The transmitting apparatus according to claim 1, wherein when the pilot signal is not recognized in either one of the first modulated signal and the second modulated signal, the output of the one is stopped. .