JP3230619B2 - High power stage modulation method for SSB broadcaster - Google Patents

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 broadcaster, and more particularly to a high power reduced carrier or all carrier SS.
The present invention relates to a high power stage modulation method for a B broadcaster.

[0002]

2. Description of the Related Art At present, a DSB transmitter using a double-sideband (hereinafter referred to as DSB) transmission system is often used as a short-wave band high-power transmitter used for international broadcasting and the like. Fig. 2 shows the high power D currently used for international broadcasting, etc.
It is a block diagram of a structure of an SB transmitter (DSB broadcasting machine).
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 denotes a modulation amplifier, which includes a push-pull amplifier using an output transformer and having a linear amplification function in class B operation.
In this DSB broadcaster, a radio frequency carrier wave b2 generated 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 amplified by a modulation amplifier 23. A signal d2 obtained by superimposing the AF signal power c2 taken out through the output transformer on a high-voltage DC power supply is supplied to a high-frequency amplifier 22 to modulate a carrier wave to create a DSB wave e2, which is emitted from an antenna. I have.

[0003] For such current broadcasting facilities, international organizations are considering switching from the DSB transmission system to the SSB (single sideband) transmission system from the viewpoint of effective use of radio waves. Recommendations were made to use a period, and then transition to SSB broadcasting with reduced carrier transmission. At the time of transition, high power transmission is required for international broadcasting, and since the equipment of the current DSB broadcaster is expensive, the high power SSB broadcast equipment that makes full use of the equipment of the current DSB broadcaster The challenge was to achieve.

In order to solve this problem, a technical problem is how to realize a modulation scheme for producing a high-power SSB transmission wave with a reduced carrier. That is, the reduced carrier SSB transmission method is a method of transmitting a single sideband signal by reducing the carrier level in amplitude modulation.
A technical condition is to amplify and modulate the signal of the sum of the AF signal and the reduced carrier (constant amplitude). Conventional techniques for converting a current DSB broadcaster to an SSB broadcaster taking such conditions into consideration include two methods: a linear amplification method and an envelope elimination reproduction system (hereinafter, referred to as an EER method). 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 broadcasting apparatus using a linear amplification method. In the figure, 31 is a frequency synthesizer, and 32 is a high-frequency amplifier, which is obtained by modifying the high-frequency amplifier 22 of class C operation of the current DSB broadcasting machine of FIG. 2 into a linear amplifier of class B operation. 33 is an SSB converter. The AF signal a is input to the SSB converter 33,
The intermediate frequency SSB wave c3 is generated by the first subcarrier b3.
After performing frequency conversion on the second subcarrier d3, the synthesizer 31 further sets the emission frequency SS.
The frequency conversion is performed on the B wave to output a signal f3, and the transmission wave g3 amplified by the high frequency amplifier 32 is emitted from the antenna. 33-1 is a carrier wave level setting device.

[0006] Envelope erasure reproduction method (EER method)
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 to obtain an SSB transmission wave. This method can be used when an SSB modulated wave is generated by the suppressed carrier wave transmission. FIG. 4 is a block diagram showing an example of a conventional SSB broadcaster using the EER method. 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 shown in FIG.
Can be applied. 43 is an SSB converter, 43-
1 is a limiter, 44 is an envelope detector, and 45 is a linear amplifier for modulation. When two sine waves of equal amplitude are input as the AF signal a, the AF signal a is
After being converted into a wave, a part of the wave is converted via a limiter 43-1 as a phase modulation component having a constant amplitude into the frequency synthesizer 41.
And is converted to the emission frequency, and is amplified by the high frequency amplifier 42 to the required power. On the other hand, the SSB wave k output from the SSB converter 43 is rectified by the envelope detector 44 to become an envelope component m in the audio frequency band, and is power-amplified by the linear amplifier 45 for modulation. The high frequency amplifier 42 is amplitude-modulated by the superimposed signal o with the power supply and SSB
A wave is created and emitted from the antenna as a transmission output p with suppressed carrier components.

[0007]

However, the conversion 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 to suppress the distortion of the SSB transmission wave. I have to do
If the high-voltage DC power supply for the DSB broadcaster is used, there is a disadvantage that the power of the SSB wave that can be transmitted is greatly restricted. Even if the high-voltage DC power supply is modified, SSB of Peak Envelope Power (hereinafter referred to as PEP) of the same level as the carrier power of the DSB transmitted by the existing equipment
A wave, that is, an SSB wave having a power 1/4 of the 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 the time of 100% modulation is 1200 kW, but when this is modified to a linear amplification type SSB transmitter, １ ／ of 1200 kW is used. Of about 300 kW PEP. In addition, the conversion to the linear amplification method does not use the modulation amplifier 23 and its related equipment used in the DSB broadcaster shown in FIG. Become.

Further, in the case of the modification to the EER system which is the latter system, if the modulation amplifier 23 of FIG. 2 is applied as the modulation linear amplifier 45, it is sufficient if the input waveform m can be amplified as it is, but it is provided. 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 removed as shown in the waveform n, and the envelope including the DC component such as the reduced carrier SSB is output. A fatal failure occurs in that it cannot be generated. Therefore, unless some measures are taken, the EER method cannot be put to practical use as it is. As mentioned above, the international broadcasting DSB
When transitioning to the B system, international organizations should use reduced carrier SS
Since the transition to operation using the B method has been decided,
It is impossible to use the class B push-pull amplifier (modulation amplifier 23) with the output transformer of the current DSB broadcasting machine as it is as the modulation linear amplifier 45 for the above reason.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem in the prior art, and uses a high-frequency amplifier of an existing DSB broadcaster as it is, and realizes a PEP having four times the carrier power of the existing DSB broadcaster. An SSB transmission output can be obtained, and further, a class B push-pull type modulation amplifier with an output transformer is used to increase the output power as it is according to the related art, and the carrier is set to an arbitrary level. It is an object of the present invention to provide a high power stage modulation method for an SSB broadcaster capable of obtaining a high power transmission output of a reduced carrier or all carriers SSB.

[0010]

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

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, subjected to processing such as amplification separately, and then recombined. The conventional EER method for obtaining the SSB transmission wave by using the high frequency amplifier provided in the current DSB broadcasting machine as it is, and furthermore, the method of creating the SSB wave by the analog technology using the conventional filter and , DS
9 shows a specific measure for configuring a high-power reduced-carrier SSB transmitter by making use of the manufacturing technology of a class B modulation amplifier with an output transformer of the B transmitter.
In this way, we will reduce costs when changing or newly installing transmission equipment in line with the adoption of SSB for international broadcasting, etc., as well as solving basic design problems such as transmitter configuration and transmission power setting. It is a thing.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a frequency synthesizer that can be modulated at an intermediate frequency, and 2 denotes a high-frequency amplifier, which can use the high-frequency amplifier 22 for amplifying the carrier 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.
Of the present modulation amplifier 23 can be utilized. 5 is an envelope extractor, 5-1 is a rectifier, and 5-2 is a filter for removing unnecessary frequency components contained in the rectified signal o to obtain an envelope component.

The difference from the conventional EER system shown in FIG. 4 is that the signal g including the envelope component output from the signal converter 3 is amplified, and the high-voltage power supply supplied to the class C power amplifier of the high frequency amplifier 2 Circuit configuration. That is, FIG.
In the conventional EER system shown in FIG. 1, the output from the SSB converter 43 is detected by an envelope detector 44, and then amplified by a linear amplifier for modulation 45. 2 is provided separately from the high-voltage DC power supply similarly to the DSB broadcaster of FIG. 2, but in the present invention, after the output g of the signal converter 3 is amplified by the modulation amplifier 4,
The envelope component o is extracted by performing rectification by the envelope extractor 5. Further, the power o of the envelope component is supplied to a class C power amplifier of the high frequency amplifier 2 as a high voltage power supply, and the power is operated. Due to the difference in these circuit configurations, SSB including a carrier (DC component as an envelope) set to an arbitrary value
The transmission output j is 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 a -12 dBSSB wave. The signal converter 3 converts the AF signal a into an SSB signal c by a balanced modulator (BM) and a filter using a first subcarrier b (for example, 100 kHz) supplied from the frequency synthesizer 1, and converts the AF signal a 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 generated by the first subcarrier b is converted to an amplitude limiter (LIM).
3-1 through the phase adjuster (φ) to the BM, and the intermediate frequency (for example, 2.7 MHz) supplied from the frequency synthesizer 1 by the second subcarrier d (for example, 2.7 MHz).
2.8 MHz). This phase modulation component signal e is supplied to the frequency synthesizer 1, and the frequency synthesizer 1 converts the signal e into an 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 an envelope component, an SSB wave c generated by the AF signal a and the first subcarrier b and a third subcarrier obtained by converting the first subcarrier b by the frequency converter 3-2. The frequency of a carrier (for example, 90 kHz) is 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 to a required power by a class B push-pull (PP) power amplifier 4-1. The output taken out via the output transformer 4-2 is sent to the envelope extractor 5 and rectified by the rectifier 5-1 to form a positive voltage pulsating wave h, which passes through the low-pass filter 5-2. Thus, the envelope power of the waveform i of the SSB signal is obtained. By driving the final class C power amplifier of the high-frequency amplifier 2 using this envelope power i as a high-voltage power supply, a 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 used. It is preferable that the frequency of the output transformer 4-2 be as low as possible.
This is because it is easy to manufacture an envelope extractor and the like.

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

[0017]

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

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a conventional DSB broadcaster.

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frequency synthesizer 2 High frequency amplifier 3 Signal converter 4 Modulation amplifier 5 Envelope extractor 21, 31, 41 Frequency synthesizer 22, 32, 42 High frequency amplifier 23, 45 Modulation amplifier 33, 43 SSB converter 44 Detector

Claims (1)

(57) [Claims] 1. An SSB signal is created from an input audio signal and a first sub-carrier, and the amplitude of the SSB signal is limited, and then a phase information component subjected to frequency conversion by a second sub-carrier is output. A signal converter that outputs a signal containing an envelope information component obtained by performing frequency conversion on the SSB signal by a third subcarrier, and converts the phase information component from the signal converter into a transmission frequency and outputs the signal. A frequency synthesizer, a modulation amplifier that amplifies and outputs a signal including the envelope information component from the signal converter by a class B push-pull configuration, and rectifies a signal from the modulation amplifier to perform low-pass filtering. An envelope extractor that outputs an envelope power, and amplifies a signal from the frequency synthesizer and combines the amplified power with the envelope power to reduce the 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.