JPH06252647A - High power stage modulation system for ssb broadcast equipment - Google Patents

Abstract

PURPOSE:To obtain a transmission output of a short wave SSB broadcast equipment in the reduced carrier or full carrier transmission system and to attain high power. CONSTITUTION:An AF signal is inputted to a signal converter 3 and after an SSB signal is generated by a subcarrier, a signal (g) including a phase modulation component (e) and an envelope component are outputted separately. The signal (g) including the envelope component is linearly amplified by a modulation amplifier 4 and an envelope component (i) is obtained by an envelope extraction device 5. The phase modulation component (e) is converted into a transmission frequency signal by a frequency synthesizer 1 and amplified by a high frequency amplifier 2 operated by using the power of the envelope component (i) as its high voltage power supply to obtain a reduced carrier or a full carrier SSB transmission output (j) with a desired high power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short wave SSB broadcasting device, and more particularly to a high power reduced carrier wave or full carrier wave SS.
The present invention relates to a high power stage modulation system for B broadcast equipment.

[0002]

2. Description of the Related Art At present, a DSB transmitter based on a double sideband (hereinafter referred to as DSB) transmission system is often used as a high power transmitter in the short wave band which is used for international broadcasting. Fig. 2 shows the large electric power D used in current international broadcasting.
It is a block diagram of an SB transmitter (DSB broadcaster).
In the figure, 21 is a frequency synthesizer, and 22 is a high-efficiency high-frequency amplifier for class C operation or the like. Reference numeral 23 is a modulation amplifier, which uses an output transformer and is provided with a push-pull amplifier having a linear amplification function in class B operation.
In this DSB broadcaster, a radio frequency carrier b2 created by a frequency synthesizer 21 is amplified to a predetermined power by a high frequency amplifier 22, and an audio frequency signal (AF signal) a such as voice is power amplified by a modulation amplifier 23. A signal d2 obtained by superimposing the AF signal power c2 extracted through the output transformer on a high-voltage DC power source is supplied to a high-frequency amplifier 22 to modulate a carrier wave, create a DSB wave e2, and emit it from an antenna. There is.

For such a current broadcasting facility, an international organization is considering switching from the DSB transmission system to the SSB (single sideband) transmission system from the viewpoint of effective use of radio waves, and provisionally sets all-carrier SSB. It was recommended that the period should be used, and then the SSB broadcasting by the reduced carrier transmission should be started. At the time of transition, high power transmission is required for international broadcasting, and since the equipment of the current DSB broadcasting equipment is expensive, the high power SSB broadcasting equipment that makes maximum use of the equipment of the current DSB broadcasting equipment. The realization of

In order to solve this problem, a technical problem is how to realize a modulation method for producing a high power SSB transmission wave of a reduced carrier wave. That is, the reduced carrier SSB transmission method is a method of reducing the carrier level in amplitude modulation and transmitting a single sideband signal,
The technical condition is to amplify and modulate the signal of the sum of the AF signal and the reduced carrier wave (constant amplitude). Conventional techniques for converting an existing DSB broadcaster into an SSB broadcaster in consideration of such conditions include a linear amplification system and an envelope elimination reproduction system (Envelope Elimination Restoration system, hereinafter referred to as EER system). There are two methods.

First, the former linear amplification method will be described. FIG. 3 is a block diagram showing an example of a conventional SSB broadcaster using a linear amplification method. In the figure, 31 is a frequency synthesizer and 32 is a high frequency amplifier, which is a modification of the class C high frequency amplifier 22 of the current DSB broadcasting machine in FIG. 2 into a class B linear amplifier. 33 is an SSB converter. The AF signal a is input to the SSB converter 33,
The first sub-carrier wave b3 causes the intermediate frequency SSB wave c3
Is generated, frequency conversion is performed using the second subcarrier d3, and then the synthesizer 31 further sets the emission frequency SS.
Frequency conversion is performed on the B wave to output the signal f3, and the transmission wave g3 amplified by the high frequency amplifier 32 is emitted from the antenna. 33-1 is a carrier level setter.

The latter envelope erasure reproduction system (EER system)
Is a method of separating an SSB wave into a phase-modulated component (phase information component) and an envelope information component, separately performing processing such as amplification, and then recombining them to obtain an SSB transmission wave. This is a method that can be used when, for example, creating an SSB modulated wave by transmitting the suppressed carrier wave. FIG. 4 is a block diagram showing an example of a conventional ESB SSB broadcaster. In the figure, 41 is a frequency synthesizer, 42 is a high frequency amplifier, and the high frequency amplifier 22 of the current DSB transmitter of FIG.
Can be applied. 43 is an SSB converter, 43-
Reference numeral 1 is a limiter, 44 is an envelope detector, and 45 is a modulation linear amplifier. When two sine waves of equal amplitude are input as the AF signal a, the AF signal a is sent to the SSB converter 43 by SSB.
After being converted into a wave, a part of it is passed through the limiter 43-1 as a phase modulation component of constant amplitude to the frequency synthesizer 41.
Is converted to a firing frequency and amplified to a required power by the high frequency amplifier 42. On the other hand, the SSB wave k output from the SSB converter 43 is rectified by the envelope detector 44 to become the envelope component m of the audio frequency band, power-amplified by the modulation linear amplifier 45, and its output n and high voltage DC. Amplitude modulation is applied to the high-frequency amplifier 42 by the superposed signal o with the power source, and SSB is applied.
A wave is generated and is emitted from the antenna as a transmission output p in which the carrier component is suppressed.

[0007]

However, the modification to the linear amplification method, which is the former method, can be performed relatively easily, but the linearity of the high frequency amplifier 32 is maintained in order to suppress the distortion of the SSB transmission wave. Because I have to
There is a drawback in that the power of the SSB wave that can be sent out is greatly restricted if the high-voltage DC power supply for the DSB broadcaster is used as it is. Even if the high-voltage DC power supply is modified, the SSB of the peak envelope power (hereinafter referred to as PEP) is about the same as the carrier power of the DSB transmitted by the existing equipment.
A wave, that is, an SSB wave having a power of ¼ of PEP of a 100% modulated DSB wave can be transmitted. For example, in the case of a 300 kW-DSB transmitter used for international broadcasting, the PEP at 100% modulation is 1200 kW, but if this is converted to a linear amplification type SSB transmitter, it is 1/4 of 1200 kW. Only a transmission output of about 300 kW PEP can be obtained. Further, in the modification to the linear amplification method, there is a drawback that the modulation amplifier 23 used in the DSB broadcasting device of FIG. 2 and its related equipment are not used, and it becomes completely unnecessary, resulting in an economical loss. Become.

Further, in the case of the modification to the EER method which is the latter method described above, if the modulation amplifier 23 of FIG. 2 is applied as the modulation linear amplifier 45, it suffices if the input waveform m can be amplified as it is. Since the output transformer does not pass the DC component, the envelope output by the two equal amplitude AF signal inputs has the DC component deleted as shown by the waveform n, and the envelope containing the DC component such as the reduced carrier wave SSB. There is a fatal problem that can not be generated. Therefore, this EER system cannot be put to practical use as it is without taking some measures. As mentioned above, from the international broadcasting DSB system to SS
At the time of transition to the B system, an international organization reduced carrier wave SS
Since it is decided to shift to operation by the B method,
It is impossible to use the class B push-pull amplifier (modulation amplifier 23) with an output transformer of the current DSB broadcaster as it is as the modulation linear amplifier 45 for the above reason.

The object of the present invention is to solve the above problems in the prior art, and to use the high frequency amplifier of the existing DSB broadcast equipment as it is, to obtain a PEP of four times the carrier power. The SSB transmission output can be obtained, and further, the output power of the class B push-pull type modulation amplifier with the output transformer is increased as it is according to the prior art, and the SSB in which the carrier is set to an arbitrary level, that is, An object of the present invention is to provide a high power stage modulation system for an SSB broadcaster that can obtain a high power transmission output of a reduced carrier wave or an all carrier wave SSB.

[0010]

According to the high power stage modulation method of an SSB broadcaster of the present invention, an SSB signal is created by an input audio frequency signal and a first subcarrier, and the amplitude of the SSB signal is limited. After that, the phase information component frequency-converted by the second subcarrier is output and the SSB
A signal converter that outputs a signal including an envelope information component obtained by frequency-converting the signal by a third subcarrier, and a frequency synthesizer that converts the phase information component from the signal converter into a transmission frequency and outputs the transmission frequency. , A modulation amplifier for amplifying and outputting a signal including the envelope information component from the signal converter by a class B push-pull configuration, and an envelope by rectifying and low-pass filtering the signal from the modulation amplifier An envelope extractor for outputting power and a high frequency amplifier for amplifying a signal from the frequency synthesizer and combining with the envelope power to output a desired reduced carrier SSB or full carrier SSB transmission output It is characterized by.

That is, according to the present invention, after the AF signal is converted into an SSB wave, it is separated into an amplitude (envelope) information component and a phase information component, separately processed such as amplification, and then recombined. By improving the conventional EER system to obtain SSB transmission wave by using the high frequency amplifier installed in the current DSB broadcasting equipment as it is, , DS
It shows a concrete measure for constructing a high power reduced carrier SSB transmitter by making it possible to utilize the manufacturing technique of a class B modulation amplifier with an output transformer of the B transmitter.
This will reduce costs when changing or newly installing transmission equipment due to the introduction of SSB such as international broadcasting, and will also solve basic design problems such as transmitter configuration and transmission power value setting. It is a thing.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a frequency synthesizer that is modulated at an intermediate frequency, and 2 is a high frequency amplifier, which can utilize the high frequency amplifier 22 for carrier amplification of the current DSB transmitter shown in FIG. 3 is a signal converter. Reference numeral 4 denotes a modulation amplifier, which includes a class B power amplifier 4-1 and an output transformer 4-2.
It is possible to utilize the manufacturing technique of the current modulation amplifier 23. Reference numeral 5 is an envelope extractor, 5-1 is a rectifier, and 5-2 is a filter for removing an unnecessary frequency component contained in the rectified signal o to obtain an envelope component.

The difference from the conventional EER method shown in FIG. 4 is that the high-voltage power supply for amplifying the signal g including the envelope component output from the signal converter 3 and the class C power amplifier of the high frequency amplifier 2 is provided. It is a circuit configuration of. That is, FIG.
In the conventional EER system shown in (1), the output from the SSB converter 43 is detected by the envelope detector 44, and then amplified by the modulation linear amplifier 45. , Which are individually supplied from the high voltage DC power source as in the DSB broadcasting device of FIG. 2, in the present invention, after the output g of the signal converter 3 is amplified by the modulation amplifier 4,
The envelope component 5 is rectified to extract the envelope component o. Further, the power o of the envelope component is supplied to the class C power amplifier of the high frequency amplifier 2 as a high voltage power source to operate it. Due to the difference in these circuit configurations, the SSB containing the carrier wave (DC component as the envelope) set to an arbitrary value
The transmission output j will be obtained.

The operation of the present invention will be described with reference to FIG. The waveform of each part in FIG. 1 shows a schematic shape in the case of −12 dBSBS wave. The signal converter 3 converts the AF signal a into an SSB signal c with a balanced modulator (BM) and a filter by the first subcarrier b (for example, 100 kHz) supplied from the frequency synthesizer 1, and converts it into a phase modulation component e. And a signal g including an envelope component. That is, in order to obtain the phase modulation component e, the SSB wave c created by the first subcarrier b is amplitude-limited (LIM).
It is given to BM through 3-1 and a phase adjuster (φ), and an intermediate frequency (for example, 2.7 MHz) is supplied by the second subcarrier d (for example, 2.7 MHz) supplied from the frequency synthesizer 1.
2.8 MHz) signal e. This phase modulation component signal e is supplied to the frequency synthesizer 1, and the frequency synthesizer 1 sends this signal e to the emission frequency band (for example, 1
(0 MHz) frequency-converted and output and input to the high-frequency amplifier 2.

On the other hand, for the envelope component, the SSB wave c generated by the AF signal a and the first subcarrier b and the third subcarrier obtained by converting the first subcarrier b by the frequency converter 3-2. A carrier wave (for example, 90 kHz) is frequency-converted using a BM and a filter, and an SSB wave g having a carrier frequency of 10 kHz is output and supplied to the modulation amplifier 4. In the modulation amplifier 4, the SSB wave g is linearly amplified by the class B push-pull (PP) power amplifier 4-1 to the required power. The output taken out through the output transformer 4-2 is sent to the envelope extractor 5 and rectified by the rectifier 5-1 into a positive voltage pulsating wave h, which passes through the low-pass filter 5-2. Gives the envelope power of the waveform i of the SSB signal. By driving the final stage class C power amplifier of the high frequency amplifier 2 by using this envelope power i as a high voltage power supply, the reduced carrier SSB signal wave j in the emission frequency band is created and transmitted. The reason for frequency-converting the SSB wave c having a carrier wave of 100 kHz into the SSB wave g having a carrier wave of about 10 kHz in the signal converter 3 is that the class B push-pull power amplifier 4-1 of the modulation amplifier 4 is It is better to make the amplification by the output transformer 4-2 as low as possible,
This is because it is easy to manufacture an envelope extractor or the like.

As can be seen from the above description, the SS of the present invention
In the configuration of the B broadcaster, 10 in the DSB transmitter
It is clear that the transmission output up to the same level as the PEP at the time of 0% modulation can be obtained.
It can be seen that when compared with the maximum output of the transmitter (for example, 300 kW), the transmission output of the SSB wave of 1200 kW, which is four times that of the maximum output, is obtained. In addition, since the signal g including the envelope component is converted to the intermediate frequency band, amplified to the required power, and then rectified to obtain the envelope component, the signal corresponding to the signal including the DC component in the envelope is supported. Because you can
It is also clear that the SSB wave in which the carrier wave is set to an arbitrary level, for example, the reduced carrier wave SSB or the all-carrier wave SSB system can be used for broadcasting. Further, according to the transmission system having the configuration of the present invention, the PEP at the time of 100% modulation of the high power stage modulation DSB transmitter including SSB and DSB, without causing waveform distortion even with an analog amplitude modulation wave of any radio wave format. The output can be increased to the value of and sent.

[0017]

As described in detail above, the following effects can be obtained by implementing the present invention. (1) International broadcasting by short wave of all carrier SSB and low-frequency carrier SSB, which are scheduled to be switched from DSB broadcasting in the future, can be realized with minimum cost. (2) Using the non-linear high frequency amplifier of the current DSB transmitter as it is, PEP of 4 times the carrier rated output.
SSB waves can be transmitted. (3) Applying the technology of class B modulation amplifier with output transformer used in the current DSB transmitter,
A high power SSB transmission system can be constructed by increasing the output power of the amplifier. (4) Since the final stage of the amplifier for the signal including the envelope component has a class B push-pull power amplifier configuration, good linearity similar to that obtained by the DSB method can be obtained, and SS
It can be expected that the distortion of the B transmission wave is reduced. (5) Since each modulation part is configured by an analog method using a filter, there is no occurrence of noise as seen in the case of the switching method, and the low-pass filter for extracting the envelope power also uses the digital method. Compared with the case, it becomes simpler and economically and technically advantageous.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a conventional DSB broadcast device.

FIG. 3 is a block diagram showing an example of a conventional SSB broadcasting device.

FIG. 4 is a block diagram showing another example of a conventional SSB broadcasting device.

[Explanation of symbols]

 1 Frequency Synthesizer 2 High Frequency Amplifier 3 Signal Converter 4 Modulating Amplifier 5 Envelope Extractor 21, 31, 41 Frequency Synthesizer 22, 32, 42 High Frequency Amplifier 23, 45 Modulating Amplifier 33, 43 SSB Converter 44 Detector

Claims (1)

[Claims] 1. An SSB signal is created from an input audio frequency signal and a first subcarrier, the amplitude of the SSB signal is limited, and then a phase information component subjected to frequency conversion by the second subcarrier is output. At the same time, a signal converter that outputs a signal including an envelope information component obtained by frequency-converting the SSB signal with a third subcarrier, and the phase information component from the signal converter that is converted into a transmission frequency and output. Frequency synthesizer, a modulation amplifier for amplifying and outputting a signal including the envelope information component from the signal converter by a class B push-pull configuration, and a low-pass filter for rectifying the signal from the modulation amplifier. And an envelope extractor for outputting envelope power, and a signal from the frequency synthesizer is amplified and combined with the envelope power to obtain a desired reduced carrier SSB or High power stage modulation scheme SSB broadcasting machine equipped with a high-frequency amplifier delivering full carrier SSB transmission output.