JPH0750607A - Satellite broadcast receiver - Google Patents

Abstract

PURPOSE:To provide a satellite broadcast receiver for miniaturizing a reception antenna relating to the satellite broadcast receiver for switching and receiving one of the communication satellite broadcast signals of vertical polarized waves or horizontal polarized waves transmitted from two satellites for communication. CONSTITUTION:First and second reception signals obtained by simultaneously receiving respective CS broadcast signals from two adjacent communication satellites by the reception antenna are demodulated by FM demodulation parts 5a and 5b and then turned to video signals by video signal processing parts 8a and 8b. The demodulated video signals are inverted in the phase inversion circuit of the processing system of reception signals mixed in desired waves as interference waves among the phase inversion circuits 9a and 9b, level- adjusted in the signal level adjustment circuit of the processing system of the reception signals mixed in the desired waves as the interference waves among the signal level adjustement circuits 10a and 10b and added in an adding circuit 14. Thus, the interference waves mixed in the demodulated video signals of the desired waves are cancelled and removed or reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcast receiver, and more particularly to a vertically polarized or horizontally polarized communication satellite (CS: Communicati) transmitted from two communication satellites.
on Satellite) The present invention relates to a satellite broadcast receiving apparatus for switching and receiving any of broadcast signals.

[0002]

2. Description of the Related Art FIG. 3 shows a block diagram of an example of a conventional satellite broadcast receiving apparatus. This conventional satellite broadcasting receiver has two
A vertical (V) polarized wave and a horizontal (H) polarized CS broadcast signal from each of the base communication satellites is a so-called multi-beam type receiving antenna, or a single-beam antenna with two surfaces corresponding to the number of satellites. 2 converted into the first intermediate frequency by the low noise converter of the receiving antenna
It has two signal input terminals 1 and 2.

Here, the suffix a in FIG.
The receiving system of the first communication satellite A of the base communication satellites,
The suffix b indicates that it is the receiving system of the second communication satellite B. The input terminals 1a and 1b are the first signals obtained by frequency-converting the received signal of the vertically polarized CS broadcast signal.
Input terminals for the intermediate frequency signal, and input terminals 2a and 2b are input terminals for the first intermediate frequency signal obtained by frequency-converting the received signal of the horizontally polarized CS broadcast signal.

The V / H switching circuit 3 connects the input terminals 1a and 1b to the input terminals of the frequency converters 4a and 4b when receiving the vertically polarized wave and converts the frequency of the input terminals 2a and 2b when receiving the horizontally polarized wave. Connected to the input terminals of the devices 4a and 4b, respectively.
The frequency converters 4a and 4b frequency-convert the input first intermediate frequency signal with the local oscillation frequency corresponding to the channel selected by the channel selection controller 11 to convert the first intermediate frequency signal of the selected channel into a predetermined first frequency signal. 2 Frequency conversion to an intermediate frequency signal.

The FM demodulators 5a and 5b are frequency converters 4.
The second intermediate frequency signals from a and 4b are frequency modulated waves (F
Since it is an M-modulated wave), it is demodulated to obtain a demodulated signal. This demodulated signal is a multiplexed signal of a video signal and an audio signal. The audio signal processing units 7a and 7b separate the audio signal from the demodulated signal, perform predetermined signal processing, and output a baseband audio signal. In addition, the video signal processing unit 8a,
8b separates the video signal from the demodulated signal, performs predetermined signal processing, and outputs a baseband video signal.

The voice selection circuit 15 receives both output signals of the voice signal processing units 7a and 7b as input signals,
Based on the select signal corresponding to the selected channel from the channel selection control unit 11, one audio signal corresponding to the selected channel is selectively output to the output terminal 18. On the other hand, the video selection circuit 19 receives both the output signals of the video signal processing units 8a and 8b as input signals, and based on the select signal corresponding to the channel selected, one video signal corresponding to the channel selected. Is selectively output to the output terminal 17.

The operation of the conventional receiving apparatus having the above-mentioned configuration when the vertically polarized wave of the first communication satellite A is the desired received wave will be described. In this case, the V / H switching circuit 3 switches the input terminals 1a and 1b to the input terminals of the frequency conversion units 4a and 4b, respectively, under the control of the channel selection control unit 11.

As a result, the first intermediate frequency signal obtained by frequency-converting the vertically polarized CS broadcast signal of the first communication satellite A by the low noise converter section of the receiving antenna is input through the IF cable to the input terminal 1a. To V and
It is input to the frequency conversion unit 4a through the / H switching circuit 3. Here, if the diameter of the receiving antenna is small,
The first intermediate frequency signal obtained by frequency-converting the vertically polarized CS broadcast signal of the second communication satellite B adjacent to the second communication satellite A by the low noise converter section of the receiving antenna is input through the IF cable. Input to 1b, and V /
It is input to the frequency conversion unit 4b through the H switching circuit 3 and interferes with the output of the desired wave image signal as an interference wave depending on the reception level.

Therefore, conventionally, in order to reduce the reception level of the vertically polarized wave of the second communication satellite B as much as possible, the diameter of the receiving antenna is large with a narrow directivity (for example, diameter 60 cm to 75 cm).
(cm or more) is set. Thus, the video signal obtained by receiving and demodulating the vertically polarized CS broadcast signal of the first communication satellite A, which is a desired wave, interferes with the vertically polarized CS broadcast signal of the second communication satellite B. It is possible to output to the output terminal 17 from the video selection circuit 19 without receiving the signal.

The voice signal is pulse code modulated (PC
Since it is transmitted as M), it is less likely to be interfered by interference from adjacent communication satellites compared to video signals, and if the diameter of the receiving antenna is up to about 45 cm in diameter, practical use is not required to take measures against interference. There is no problem above.

[0011]

By the way, since CS broadcasting uses a plurality of medium power communication satellites arranged at intervals of 4 ° in a geostationary orbit on the equator, a broadcasting satellite (BS: Broadcasting Satellite) using a high power satellite is used.
Unlike e), the signal level from the satellite is low, and in order to reduce the reception level of the interfering radio waves from the adjacent satellite as much as possible, the receiving antenna has a diameter of 35c which is currently popular.
It is necessary to have a large diameter of 60 cm to 75 cm or more as compared with a receiving antenna for BS broadcasting of m to 45 cm class.

For this reason, while the BS broadcasting receiving antenna can be easily installed on a veranda or the like by an individual,
In the case of a large-diameter receiving antenna used in this CS broadcasting, dedicated installation work is indispensable due to the problem of wind pressure load on the receiving antenna. For this reason, the receiving device for CS broadcasting has a large cost compared with the BS receiving device because the cost of installation metal fittings and installation work is required in addition to the cost increase due to the enlargement of the antenna, which hinders the spread of CS broadcasting. This is one of the causes.

Further, due to the recent progress in the manufacturing technology of the antenna for satellite broadcasting reception, the efficiency of the antenna has been steadily improved, and in combination with the progress of the noise reduction of the semiconductor device for low noise amplification, the antenna aperture is small. It is thought that the commercialization will further progress in the future. However, in the case of CS broadcasting, since the communication satellites are placed close to the geostationary orbit on the equator at an interval of 4 ° as described above, if the antenna aperture is made too small, its directivity will spread. However, there is a limit to miniaturization of the receiving antenna because it receives interference from adjacent satellites.

Further, conventionally, in the field of microwave radio communication, there are various methods for reducing the interference wave signal by controlling and synthesizing the phase and amplitude of the interference wave signal included in the desired wave received. Although proposed (for example, Japanese Patent Laid-Open Nos. 62-147818 and 2-146824), all of these require a dedicated antenna for monitoring an interference wave, and a baseband signal is required. Although signal processing is performed at the high-frequency signal stage before demodulation, these measures have not been taken in the satellite broadcasting receiver for CS broadcasting.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a satellite broadcast receiving apparatus that solves the above problems by simultaneously receiving broadcast signals from two adjacent satellites and controlling the amplitudes and phases of the received signals to combine them.

[0016]

In order to achieve the above object, the present invention provides first and second received signals obtained by simultaneously receiving respective broadcast signals from first and second satellites by a receiving antenna. Are separately frequency-converted into intermediate frequency signals, and then separately demodulated by the demodulation means to take out the first and second demodulated signals of the baseband, and the demodulated signal of the channel selected from the first and second demodulated signals. In the satellite broadcast receiving apparatus for selectively outputting, the waveform adjustment for inverting the phase of one demodulation signal according to channel selection and adjusting the signal level of one demodulation signal of the first and second demodulation signals Circuit, and the first and second circuits extracted from the waveform adjusting circuit
And an adder circuit for adding and synthesizing the demodulated signals and outputting the demodulated signals.

[0017]

In the present invention, for the received signal of one satellite of the desired channel selected from the first and second satellites,
Even if the received signal of the other satellite is mixed as an interference wave,
The waveform adjusting circuit generates a demodulated signal having a level almost equal to that of the interference wave in the desired wave and having a phase inversion, and adds the resultant demodulated signal to the received demodulated signal of the desired wave in the adding circuit. The interference wave included in the reception demodulation signal of the desired wave (the reception demodulation signal of one satellite of the desired channel selection) can be canceled or reduced.

[0018]

1 is a block diagram of an embodiment of the present invention. In the figure, the same components as those in FIG.
The description is omitted. In FIG. 1, the phase inversion circuit 9a
Demodulated video signals from the video signal processing units 8a and 8b are input to and 9b, respectively, and the phases thereof are non-inverted or inverted based on a control signal from the phase inversion / non-inversion control unit 12.

The signal level adjusting circuits 10a and 10 are also provided.
Demodulated video signals that have passed through the phase inversion circuits 9a and 9b are input to b, and the signal level thereof is not adjusted or adjusted based on the control signal from the signal level adjustment / non-adjustment control unit 13. The adder circuit 14 receives the demodulated video signals that have passed through the signal level adjusting circuits 10a and 10b, adds and combines them, and outputs the resultant composite video signal to an output terminal 17
Output to.

The phase inversion circuits 9a and 9b, the signal level adjustment circuits 10a and 10b, the phase inversion / non-inversion control section 12 and the signal level adjustment / non-adjustment control section 13 constitute the waveform adjustment circuit. ing. Further, the phase inversion / non-inversion control unit 12 and the signal level adjustment / non-adjustment control unit 13 are
The phase inversion circuits 9a and 9b and the signal level adjusting circuits 10a and 10b are controlled according to the output channel selection signal of the channel channel selection control unit 21.

FIG. 2 shows the phase inversion / non-inversion controller 12 described above.
And the signal level adjustment / non-adjustment control unit 13 for controlling the phase inversion circuits 9a and 9b and the signal level adjustment circuits 10a and 10
It is a figure which shows the control operation | movement of b collectively. As can be seen from the figure, when the V polarized wave of the communication satellite A, which is the first satellite, is the desired wave, the V polarization of the adjacent communication satellite B, which is the second satellite, is increased.
Polarization acts as an interference wave. At this time, the phase inversion circuit 9a outputs the input signal as it is, and the phase inversion circuit 9b inverts the phase of the input signal. In the above case,
The signal level adjusting circuit 10a outputs the input signal as it is, and the signal level adjusting circuit 10b adjusts the signal level of the input signal.

Similarly, when the H polarized wave of the communication satellite A is a desired wave, the H polarized wave of the communication satellite B acts as an interference wave. At this time, the phase inversion circuit 9a outputs the input signal as it is, and the phase inversion circuit 9b inverts the phase of the input signal. In the above case, the signal level adjusting circuit 10a
Outputs the input signal as it is, and the signal level adjusting circuit 10b adjusts the signal level of the input signal.

When the V polarization or H polarization of the communication satellite B is the desired wave, the V polarization or H polarization of the communication satellite A acts as an interference wave. At this time, the phase inversion circuit 9b outputs the input signal as it is, and the phase inversion circuit 9a inverts the phase of the input signal. In the above case, the signal level adjusting circuit 10b outputs the input signal as it is, and the signal level adjusting circuit 10a adjusts the signal level of the input signal.

As described above, the phase inverting circuits 9a and 9b and the signal level adjusting circuits 10a and 10b are the phase inverting circuits of the reception signal processing system (the reception signal processing system of the desired wave) of the communication satellite of the channel to be selected. While the signal level adjusting circuit does not operate and outputs the input signal as it is, the phase inversion circuit and the signal level adjusting circuit of the processing system of the received signal which becomes an interference wave respectively have a predetermined value. Controlled to perform an action.

Next, the operation of the embodiment shown in FIG. 1 will be described. Now, as in the case of FIG. 3, the desired wave is the V polarized wave of the communication satellite A, and the aperture of the receiving antenna used is small.
It is assumed that the polarization is mixed as an interference wave, and the V polarization of the adjacent communication satellite A is mixed as an interference wave in the V polarization of the communication satellite B.

As a result, in the first intermediate frequency signal input to the input terminal 1a of FIG. 1, the V polarized wave from the communication satellite B is included in the main signal obtained by receiving the V polarized wave from the communication satellite A. Includes an interference wave component generated by mixing. This first
The intermediate frequency signal is converted into a second intermediate frequency signal by the frequency conversion unit 4a, demodulated by the FM demodulation unit 5a, and then supplied to the audio signal processing unit 7a and the video signal processing unit 8a, respectively. Each is restored to a signal.

On the other hand, in the first intermediate frequency signal input to the input terminal 1b, the V polarized wave from the communication satellite A is mixed in the main signal obtained by receiving the V polarized wave from the communication satellite B. The generated interference wave component is included. The first intermediate frequency signal is converted into a second intermediate frequency signal by the frequency conversion unit 4b, demodulated by the FM demodulation unit 5b, and then the audio signal processing unit 7
b and the video signal processing unit 8b, respectively, to restore the audio signal and the video signal, respectively.

Here, as shown in FIG. 2, when the desired wave is the V polarization of the communication satellite A, the phase inversion circuit 9a and the signal level adjusting circuit 10a do not operate, and the input signal is directly input to the subsequent circuit. The video signal processing section 8
The demodulated video signal from a passes through the phase inverting circuit 9a and the signal level adjusting circuit 10a as it is and is input to the adding circuit 14.

On the other hand, the demodulated video signal from the video signal processing unit 8b is phase-inverted by the phase inversion circuit 9b, and then the signal level adjusting circuit 10b converts the interference wave component included in the signal processing system of the communication satellite A. The signal level is attenuated to a level equivalent to the level and supplied to the addition circuit 14.

As a result, the interference wave component contained in the V-polarized wave reception demodulated video signal of the communication satellite A which has passed through the signal level adjusting circuit 10a which is the channel selected in the adding circuit 14 is changed to the signal level adjusting circuit 10b. The output signal will be canceled out or significantly reduced. Therefore,
A high quality video signal of the selected channel is output to the output terminal 17. In the case of other desired waves, the interference wave component is canceled or removed or largely attenuated in the same manner as above.

Signal level adjusting circuits 10a and 10
The level adjustment of the demodulated video signal of the reception signal processing system on the non-selected channel side, which corresponds to the level of the interference wave component due to b,
By operating the volume or the like of the manual level adjusting operation unit 16 while watching the actual received image displayed on the television monitor (not shown) to which the image signal from the output terminal 17 is input, the monitor image in the monitor image is displayed. This is done by making the noise due to the interference less noticeable.

As described above, according to the present embodiment, even if a small-diameter receiving antenna is used, the interference due to the interference wave from the adjacent satellite is canceled or reduced without using the antenna dedicated to the interference wave removal. can do.

[0033]

As described above, according to the present invention,
The waveform adjusting circuit generates a demodulated signal at a level almost equal to that of the interference wave in the desired wave and the phase of which is inverted, and by adding it to the received demodulated signal of the desired wave by the addition circuit, Since the interference wave contained in the reception demodulation signal (the reception demodulation signal of one satellite of the desired channel selection) can be canceled or reduced, the reception antenna can be downsized as compared with the conventional one. Therefore, by miniaturizing the receiving antenna, the antenna installation work can be simplified and the installation work cost can be reduced. Further, since an antenna for an interference wave monitor other than the receiving antenna is not necessary, it is advantageous in terms of antenna installation space and cost, and thus has a feature that it greatly contributes to the spread of the CS broadcast receiving apparatus. Is.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram of a main part of FIG.

FIG. 3 is a block diagram of a conventional example. [Explanation of Codes] 1a, 1b First intermediate frequency signal input terminal 2a, 2b of vertical polarization reception signal 1st intermediate frequency signal input terminal of horizontal polarization reception signal 3 V / H switching circuit 4a, 4b Frequency conversion unit 5a 5b FM demodulation section 8a, 8b Video signal processing section 9a, 9b Phase inversion circuit 10a, 10b Signal level adjustment circuit 12 Phase inversion / non-inversion control section 13 Signal level adjustment / non-adjustment control section 14 Addition circuit 16 Manual level adjustment Operation part 17 Video signal output terminal 21 Channel tuning control part

Claims (2)

[Claims] 1. The first and second received signals obtained by simultaneously receiving the respective broadcast signals from the first and second satellites by a receiving antenna are separately frequency-converted into intermediate frequency signals and then separately by demodulation means. Demodulates to the first and second baseband
In the satellite broadcast receiving device for extracting the demodulated signal of and selecting and outputting the demodulated signal of the channel selected from the first and second demodulated signals, the satellite broadcast receiving device according to the channel selection of the first and second demodulated signals. The phase of one demodulation signal is inverted and the signal level of one demodulation signal is adjusted, and the first and second demodulation signals extracted from the waveform adjustment circuit are added and combined. A satellite broadcast receiving apparatus comprising: an adding circuit for outputting. 2. The receiving antenna is a multi-beam type receiving antenna that simultaneously receives signals from the first and second satellites, or a two-sided single beam antenna, and the first and second satellites. An antenna that simultaneously receives each of the vertically polarized wave and horizontally polarized wave broadcast signals from each, and selects the received broadcast signal of the desired one of the vertically polarized wave and the horizontally polarized wave received by the receiving antenna. And a switching circuit for converting the intermediate frequency signal to the intermediate frequency signal, and the waveform adjusting circuit keeps the phase of the demodulated signal on the satellite side of the desired channel out of the first and second demodulated signals and leaves the satellite on the undesired channel. A phase adjustment circuit for inverting the phase of the demodulation signal on the side, and the level of the demodulation signal on the satellite side of the desired channel among the first and second demodulation signals that have passed through the phase adjustment circuit, 2. The satellite broadcast receiving apparatus according to claim 1, further comprising a level adjusting circuit that adjusts a level of a satellite-side demodulated signal of a desired channel and outputs the adjusted signal to the adding circuit.