JP2021034970A - Transmission device and transmission method - Google Patents

Abstract

To provide a transmission device that employs a two-system method of transmitting RF signals and that eliminates the need for a switching unit that switches output signals and its monitoring control mechanism to reduce costs.SOLUTION: In a combination switching type transmission device, RF signals of two transmission units 1 and 2 are always combined by a transmission combination unit 3, and a combined wave is output. At the time of combination in the transmission combination unit, the phase and frequency of a standby system are matched with those of an active system. The transmission units 1 and 2 are provided with AGC units 1 and 2 and the output level of the standby system is controlled. During switching operation, the AGC units 1 and 2 of the active system and the standby system are controlled and output level transition is smoothly made without changing the output level of the combined wave.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fixed line transmission device in broadcasting, and particularly relates to a transmission device and a transmission method thereof.

In fixed line transmitters (Studio to Transmitter Link / Transmitter to Transmitter Link, hereinafter referred to as STL / TTL devices) in terrestrial digital broadcasting and FM (Frequency Modulation) radio broadcasting, etc., in order to switch when one system (working system) fails. In many cases, a two-system system equipped with a backup system (standby system) is adopted. The configuration of the transmitter of a general STL / TTL device is roughly divided into four according to the function. The modulation unit, IF, which modulates the baseband signal by the specified modulation method and converts it into an IF (Intermediate Frequency) signal. From the transmitter that up-converts the signal to the specified RF (Radio Frequency) signal, the switching unit that switches the RF signal with the redundant system, and the monitoring control unit that monitors the abnormality of the entire system and controls the switching unit. It is composed. If an abnormality is detected in the transmission unit of the active system, the monitoring control unit outputs a command to the switching unit to switch from the active system to the standby system. The monitoring and control unit is also responsible for weighting abnormalities such as switching immediately in the case of a severe abnormality and switching smoothly in the case of a minor abnormality without affecting the receiving side.

Patent Document 1 is a prior art document relating to such a technique. Patent Document 1 discloses a low power consumption transmission method and apparatus capable of transmitting at an optimum output level according to the state of a communication line.

Japanese Unexamined Patent Publication No. 2005-348105

The purpose of the above-mentioned two-system system of the STL / TTL device is to reduce the failure rate of the entire system and achieve continuous operation by providing a standby system and instantly switching to the standby system when the current system fails. .. However, since the switching unit that switches between the two systems cannot be made redundant due to its nature, the failure rate of the entire system depends on this switching unit. Usually, the switching unit is often composed of an active mechanism that requires power supply, such as a coaxial relay or a PIN diode switch. Therefore, a bypass system is often provided in the switching unit in case the power supply is cut off or the switching unit fails, but there are two disadvantages. The first is that the switching unit becomes expensive due to the provision of the surplus circuit. The second is that even though the system is normal, there is a concern that the receiver system in the subsequent stage may break down due to accidental switching to the bypass system for some reason. In addition, if the monitoring control unit that monitors the abnormality of the entire device fails, or if an abnormality occurs in the cable connecting the switching unit and the monitoring control unit, there is a concern that switching control cannot be executed even in the abnormal state. Will be done.

An object of the present invention is to solve the above-mentioned problems and to provide a transmission device and a transmission method that do not require a switching unit.

In order to achieve the above object, in the present invention, it is a transmission device of a two-system switching system that transmits an RF signal, and the outputs of the two transmitters that transmit the RF signal and the outputs of the two transmitters are combined. It includes a transmission synthesis unit that outputs a composite wave and a monitoring control unit that monitors and controls the transmission unit. The monitoring control unit controls the output level of the RF signal transmitted by the transmission unit, and the composite wave of a predetermined output level. Provided is a transmission device having a configuration in which is output from the transmission synthesis unit.

Further, in order to achieve the above object, the present invention is a transmission method of a two-system switching transmission device for transmitting RF signals, wherein the transmission device is a frequency of RF signals output by two transmission units. Provided is a transmission method in which a composite wave having a predetermined output level is transmitted by controlling the phase and output level for synthesis.

According to the present invention, in the two-system transmission device, a switching unit for switching the output signals of the two transmission devices and a monitoring control mechanism for controlling the switching unit are not required, and the cost can be reduced. ..

FIG. 6 is a system diagram showing a configuration of a combined switching type transmitter according to the first embodiment. The relationship diagram of the output level of the transmitters 1 and 2 at the time of the combined wave 33dBm which concerns on Example 1. The figure which shows the state of the output level shift at the time of a minor and severe failure which concerns on Example 1. FIG. FIG. 5 is a system diagram showing a configuration of a synthesis switching type transmission device having a feedback system in the transmission synthesis unit according to the second embodiment. The figure which shows the synthesis switching system by the local signal synthesis part which concerns on Example 3. FIG. The figure which shows the synthesis switching system by the local signal synthesis part with an AGC part which concerns on Example 3. FIG. The figure which shows one configuration example of the monitoring control unit which concerns on Examples 1, 2 and 3.

Hereinafter, embodiments for carrying out the present invention will be sequentially described with reference to the drawings. In a plurality of drawings, the same object is given the same number, and duplicate explanations are omitted in principle.

FIG. 1 shows a system diagram of a transmission device of a two-unit STL / TTL device having a transmission synthesis unit instead of a switching unit according to the first embodiment. In order to properly output the composite signal from the transmission synthesis unit 3, it is necessary to match the frequencies and phases of the RF signals in the transmission unit 1 and the transmission unit 2. For example, the transmission unit 1 is a working system and the transmission unit 2 is a standby system. The monitoring control unit 4 has a function of matching the frequencies and phases of the RF signals in the transmission unit 1 and the transmission unit 2. RF1 and RF2 input from the modulation unit are mixed with the local signals of the local oscillators 1 and 2 by the mixers 1 and 2, respectively, in the transmission unit 1 and the transmission unit 2. The monitoring control unit 4 has a built-in signal that serves as a reference for the local oscillator 1 and the local oscillator 2, and constantly distributes and outputs the RF frequency that is the output of the local oscillator 1 and the local oscillator 2 of the transmission unit 1 and the transmission unit 2. Match. Alternatively, the same effect can be obtained as a master / slave system having a configuration in which the transmission unit 1 and the transmission unit 2 are each provided with a crystal oscillator or the like that outputs a reference signal, and the reference signal of the active system is passed to the standby system. .. On the other hand, in terms of phase, the RF signals of the active system and the standby system are fed back by the directional couplers 1 and 2 in the transmission units 1 and 2, the phases are compared by the monitoring control unit 4, the difference is extracted, and the standby system is used. By controlling the phase of the RF signal by the phase control unit 2 of the above, the phases of the active system and the standby system can always be matched.

In a transmission device having the above functions, if the frequency and phase of the RF signals of the transmission unit 1 and the transmission unit 2 are matched and the output levels of the transmission unit 1 and the transmission unit 2 are the same, the transmission synthesis unit As for the output level of 3, a value that is 3 dB higher than that of the transmission unit 1 or the transmission unit 2 is output.

Under the condition that the output levels of the transmitting unit 1 and the transmitting unit 2 are the same, if the RF signal of the transmitting unit 1 or the transmitting unit 2 becomes abnormal, the combined wave output may also be affected. Therefore, proper control of the output level is required separately from the frequency and phase. This output level can be controlled to a specified output level by being controlled by the AGC unit 1 of the transmission unit 1 and the AGC unit 2 of the transmission unit 2.

For example, when 33 dBm is output from the transmission synthesis unit 3, the output level of the transmission unit 1 is controlled to be a specified level of 33 dBm. Here, the loss of the transmission synthesis unit 3 is ignored. The output level of the transmitter 2 is set to the minimum level, for example, 0 dBm. As a result, the output level of the transmission synthesis unit 3 becomes about 33 dBm.

Normally, in a two-unit STL / TTL device, semi-seamless switching that switches the receiving device without failure is possible. Here, the quasi-seamless switching means that the signal is corrected by the demodulator and switched, and the subsequent stage is not affected. Although it depends on the performance of the receiving device, if a sudden level fluctuation occurs during switching, the receiving device cannot normally follow the level and may fail. As described above, in this system, since it is necessary to make a level difference between the transmission unit 1 and the transmission unit 2, it is necessary to smoothly control the AGC at the time of quasi-seamless switching. For example, in the case of quasi-seamless switching control from the transmission unit 1 to the transmission unit 2, the output level of the transmission unit 1 is gradually lowered, and at the same time, the output level of the transmission unit 2 is gradually increased. The ideal control is that the combined wave output level, which is the total value of the output levels of the transmission unit 1 and the transmission unit 2, shifts smoothly without change.

FIG. 2 shows a relationship diagram of the output levels of the transmission unit 1 and the transmission unit 2 when the target value of the output level of the transmission synthesis unit 3 is 33 dBm. For example, when switching from the transmission unit 1 to the transmission unit 2, the output level of the transmission unit 2 is increased from 0 dBm to about 20 dBm. When the output level of the transmitter 1 is 33 dBm, if the output level of the transmitter 2 is up to about 20 dBm, there is almost no change in the composite level. After that, the output level of the transmission unit 2 is increased while decreasing the output level of the transmission unit 1 by 1 dB. For example, if the output level of the transmission unit 1 is 32 dBm, the output level can be kept constant by setting the output of the transmission unit 2 to about 26 dBm. In this way, finally, the output level of the transmission unit 2 is set to the target of 33 dBm, and the output level of the transmission unit 1 is set to 0 dBm.

Next, the operation when various abnormalities occur in the transmission device of this embodiment will be described. In this system, as shown in FIG. 1, since the transmission synthesizer 3 is a passive mechanism that does not require a power supply, it is assumed that the possibility of failure is extremely small. The location where a failure is expected is either the various control circuits of the transmission units 1 and 2 or the monitoring control unit 4. In the case of a failure of the transmitters 1 and 2, the procedure for switching to the standby system is roughly divided into two according to the severity of the failure. In the case of a minor failure, as shown in (a) of FIG. 3, the AGC units 1 and 2 gradually change the output levels of the transmission unit 1 and the transmission unit 2 to keep the combined wave output level constant. While maintaining, switch the selected unit. In the case of a serious failure, as shown in (b) of FIG. 3, the RF signal of the transmission unit 1 is stopped instantly, and the RF signal of the transmission unit 2 is adjusted by the AGC unit 2 so as to instantly reach the specified level. To do.

Further, a case where the monitoring control unit 4 fails will be described. If the monitoring control unit 4 fails, the frequency, phase, and output level cannot be controlled, so it is necessary to consider a specific fail-safe. For example, when a failure of the monitoring control unit 4 is detected, the transmission unit 1 and the transmission unit 2 are controlled as follows. The frequency has a function of holding the frequency before the failure by holding over the frequency that was controlled before the failure. Similarly, the phase also has a function of maintaining the phase that was controlled before the failure. Similarly, it is desirable to maintain the AGC control of the transmission unit 1 and the transmission unit 2 at the output level. Alternatively, the output level of the transmission unit 2 is gradually increased to a specified level. In the above example, as shown in FIG. 3, the amount is gradually increased from 0 dBm to 33 dBm. At this time, since 33 dBm has already been output by the transmission unit 1, the output level is increased by 3 dB, but if the transmission unit 1 also fails in the situation where the monitoring control unit 4 fails, the transmission unit 2 is switched to. It will be possible to continue operation.

With the transmission device of the first embodiment described in detail above, a synthesis switching method using a synthesizer that does not require a switching unit can be constructed, a failure of the switching unit is eliminated, and the cost of the transmission device can be reduced.

Build a transmitter that employs a combined switching method without a switching unit. The RF signals of the two transmitters are always combined and the combined wave is output. Synthesizers are usually passive and do not require power. When synthesizing, the phase and frequency of the standby system are adjusted to the working system. In addition, this working system means the latest working. In addition, the output level of the standby system is controlled by providing an AGC (Auto Gain Control) in the RF output circuit of the transmitter. During the switching operation, the AGC of the active system and the standby system is controlled to smoothly shift the output level without changing the output level of the combined wave.

In the synthesis switching method described in the first embodiment, control of the output level is important. The second embodiment is an embodiment of a transmission device in which the transmission synthesis unit 3 is also provided with a directional coupler, the synthesis level is fed back, and the output level is controlled by the monitoring control unit. That is, the transmission synthesis unit 5 has a directional coupler 3 and feeds back the synthesis level to the monitoring control unit 4.

In the transmission device of FIG. 4, by constantly monitoring the output level of the directional coupler 3 in the transmission synthesis unit 5, the monitoring control unit 4 can grasp that the composition level is within the specified range. For example, when the combined output level drops, the monitoring control unit 4 can control the AGC units 1 and 2 from the relationship between the output levels of the transmission unit 1 and the transmission unit 2.

Further, by adopting the above-mentioned synthesis switching method, maintainability can be improved. In the past, when an abnormality occurred in the transmission device, it often took time to determine where the cause was in the switching unit, the transmission unit, the monitoring control unit, or the connection cable. On the other hand, in the synthesis switching method of Examples 1 and 2, since there is no switching unit, it is almost unnecessary to assume the failure of the transmission synthesis units 3 and 5. As a result, only the transmission units 1 and 2 and the monitoring control unit 4 can cause an abnormality. Therefore, the approach for identifying the abnormal location when an abnormality occurs in the transmitting device becomes quick, and it is possible to contribute to the efficiency and simplification of maintenance work.

The third embodiment is an embodiment in which it is possible to construct the above-mentioned synthesis switching method of the first embodiment and the second embodiment by simple control for a circuit that is not directly affected by the level fluctuation. FIG. 5 shows a system diagram in which the output of the local signal synthesizer 6 is frequency-converted by a mixer using the local signal of the local oscillator 1 of this embodiment. The local oscillator 1 in the figure has a redundant configuration, and normally two systems are controlled by a switch, whereas when constructed by the local signal synthesizer 6 shown in FIG. 5, the two local oscillators 1 If the frequency, phase, and output level match, the output level of the combined wave will be a value increased by 3 dB. If the RF signal of the local oscillator is cut off due to some failure, the output level will be 6 dB lower than the combined wave ratio. However, the active mixer in the latter stage has a built-in amplifier that is normally used in the saturation region, and fluctuations in the output level of about 6 dB do not affect the characteristics. If the local signal is interrupted or the level fluctuates as a possible type of failure, there is no problem because the level fluctuation does not affect the subsequent stage as described above, but if the frequency or phase shifts for some reason, the combined wave also It fluctuates and may affect the latter stage.

This can be solved by controlling each local signal with AGC. FIG. 6 shows a system diagram in which an AGC circuit including AGC units 1 and 2 is mounted. The AGC unit 1 and the AGC unit 2 have a function of controlling the level output from each local oscillator 1 based on a control signal from a monitoring control unit or the like. For example, when the local oscillator 1 is used with a specified 10 dBm output, the AGC unit 2 controls the output level to a sufficiently low level of about -30 dBm. When a failure of the local oscillator 1 is detected, the output level of the AGC unit 2 is raised to 10 dBm, and the AGC unit 1 is controlled to be -30 dBm. As described above, if the level fluctuation of the synthetic wave is slight, it does not affect the subsequent stage, so that severe control of the AGC units 1 and 2 is unnecessary. This makes it possible to construct a synthesis switching method using a synthesizer that does not require a switching unit.

A control signal from the monitoring control unit is input to the AGC units 1, 2 and the like shown in the first, second and third embodiments. As an example of this monitoring control unit, a case where a central processing unit (CPU) is used will be described. FIG. 7 shows a monitoring control unit 7 using a CPU. The CPU constituting the monitoring control unit 7 of such a transmitter is installed on the circuit board constituting the transmitter of the STL / TTL device, and various abnormality information generated on the circuit board is input. .. As the abnormality information, as shown in FIG. 7, there is information such as an input level abnormality, an output level abnormality, a synchronization abnormality, a communication abnormality, a fan abnormality, and a power supply abnormality. The CPU constituting the monitoring control unit 7 receives these abnormality information and controls to perform AGC control, master / slave switching, abnormality contact output, LED lighting, and the like by executing a predetermined program.

The present invention is not limited to the above-described examples, and includes various modifications. For example, the above-mentioned examples have been described in detail for a better understanding of the present invention, and are not necessarily limited to those having all the configurations of the description.

Further, each of the above-mentioned configurations, functions, monitoring control units, etc. has been described mainly with an example of creating a program that realizes a part or all of them, but a part or all of them are designed by, for example, an integrated circuit. Needless to say, it may be realized by hardware. That is, all or part of the functions of the processing unit may be realized by, for example, an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array) instead of the program.

1, 2 Transmission unit 3, 5 Transmission synthesis unit 4, 7 Monitoring control unit 6 Local signal synthesis unit

Claims (5)

It is a two-system switching system transmission device that transmits RF (Radio Frequency) signals.
A transmission synthesizer that synthesizes the outputs of the two transmitters that transmit the RF signal and the outputs of the two transmitters and outputs a composite wave,
A monitoring control unit that monitors and controls the transmission unit is provided.
The monitoring control unit controls the output level of the RF signal transmitted by the transmission unit, and outputs a composite wave of a predetermined output level from the transmission synthesis unit.
A transmitter characterized by that. The transmitting device according to claim 1.
The monitoring control unit controls the frequency and phase of the RF signal of the transmitting unit.
A transmitter characterized by that. The transmitting device according to claim 2.
The transmission unit includes an AGC (Auto Gain Control) unit that controls the signal level of the RF signal and a directional coupler to which the output of the AGC unit is input.
The monitoring control unit controls the AGC unit based on the output of the directional coupler.
A transmitter characterized by that. The transmitting device according to claim 3.
The transmission synthesizer includes a directional coupler into which the composite wave is input.
The monitoring control unit controls the AGC unit based on the output level of the directional coupler of the transmission synthesis unit.
A transmitter characterized by that. It is a transmission method of a two-system switching transmission device that transmits RF signals.
The transmitting device controls and synthesizes the frequency, phase, and output level of the RF signals output by the two transmitting units, and transmits a synthesized wave having a predetermined output level.
A transmission method characterized by that.

Images