JPH11234665A - Satellite broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract a signal whose phase is shifted for IQ axis with a high accuracy and without frequency deviations by giving an output signal of a frequency converter to an IQ detection circuit, and adding an output signal of a frequency divider circuit to the output signal of the frequency converter so as to obtain an IQ signal. SOLUTION: A 1st intermediate frequency signal received from a 1st intermediate frequency input terminal 1 is given to a frequency converter 4 via a variable tuning band pass filter 2 and a pre-stage variable attenuator 3, where the signal is frequency-converted into a 2nd intermediate frequency signal. In this case, so-called upper local frequency conversion is conducted where an oscillation frequency of a local oscillator 18 is set higher than the 1st intermediate frequency. A local oscillation signal fed to an in-phase detector 12 and a quadrature detector 14 is obtained by applying 1/4 frequency division to the frequency of the local oscillation signal of the local oscillator 18 to produce the 2nd intermediate frequency signal. A 1/4 frequency divider circuit 19 applies a 1/4 frequency division to an output signal of the local oscillator 18. Then signals shifted by 90 degrees (orthogonal) are given to the in-phase detector 12 and the quadrature detector 14 to configure an IQ detection circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast satellite broadcast receiver.

[0002]

2. Description of the Related Art In recent years, satellite broadcasting using a communication satellite has adopted a method of transmitting a video signal by modulating the phase with the progress of digitization of signal processing. As the transmission system, the QPSK system is generally used.

[0003] Such a conventional satellite broadcast receiver is shown in FIG.
As shown in the electrical block diagram of FIG. 1, a first intermediate frequency signal input from a first intermediate frequency input terminal 1 connected to a satellite broadcast receiving antenna is roughly selected by a tunable bandpass filter 2 into a received signal. After that, the signal is input to the frequency converter 4 via the pre-variable attenuator 3 and frequency-converted into a second intermediate frequency signal. The local oscillation signal used for the frequency conversion is obtained from the second intermediate frequency local oscillator 5, which is stabilized by the PLL frequency synthesizer 6, and the oscillation frequency is stabilized with high precision.

Further, the second intermediate frequency signal frequency-converted by the frequency converter 4 is amplified by a variable gain amplifier 7, and one modulated wave of the desired channel is extracted by a channel filter 8 using a surface acoustic wave filter. Demodulator 9
Demodulation was performed.

[0005] Generally, the local oscillation signal used for frequency conversion is determined by the frequency of the input first intermediate frequency signal.
It is set to be always higher by the second intermediate frequency. With this tuning function, the second intermediate frequency becomes, for example, 480 MHz.
It is always kept constant in the z band. The second intermediate frequency signal tuned in this way is input to the channel filter 8 and band-limited to only one desired wave. As shown in FIG. 9, the demodulator 9 to which one second intermediate frequency signal selected by the channel filter 8 is input is constituted by a quadrature synchronous detection circuit for each IQ. That is, a 90-degree phase shifter 11 is used to shift the output signal of the local oscillator 10 by 90 degrees in order to realize quadrature detection, and the local oscillation frequency is almost constant in the 480 MHz band. 11 is generally realized by an RC delay circuit.

[0006] The second intermediate frequency signal input to the demodulator 9 is supplied to an in-phase detector 12 and a low-pass filter 13 which receive the output signal of the local oscillator 10 without changing the phase.
And the IQ baseband output terminals 16 and 17 via a quadrature detector 14 and a low-pass filter 15 which are input by shifting the output signal of the local oscillator 10 by 90 degrees by a 90-degree phase shifter 11. Is output to

[0007]

However, such a conventional satellite broadcast receiver having the above-described configuration requires a channel filter, a local oscillator for IQ detection, a phase shifter, and the like, and the configuration is complicated. . Therefore, the configuration is simple,
In addition, it has been desired to realize an inexpensive satellite broadcast receiver by eliminating the need for a channel filter using a surface acoustic wave filter or the like and by using a circuit configuration suitable for IC integration.

[0008]

In order to solve the above-mentioned problems, a satellite broadcast receiver according to the present invention comprises: a tunable band-pass filter for inputting a first intermediate frequency signal to limit a band; (2) a frequency converter and a local oscillator for generating an intermediate frequency signal, a frequency dividing circuit for inputting the local oscillator signal and dividing the frequency by 4, an IQ detecting circuit for quasi-synchronous detection,
A low-pass filter for each of the IQ signals;
An output signal of the frequency converter is input to an IQ detection circuit, and an IQ signal is obtained by adding an output signal of a frequency dividing circuit as a local oscillation signal of the IQ detection circuit. The local oscillation frequency is higher than the first intermediate frequency. According to the present invention, the first intermediate frequency signal is set to be higher and one third of the first intermediate frequency is set to be substantially equal to the second intermediate frequency. By setting the third intermediate frequency to be the second intermediate frequency, a local oscillation signal of the IQ detection circuit can be obtained from a frequency dividing circuit that inputs the signal of the local oscillator and divides the frequency by four. In addition, it is possible to accurately extract a signal having a phase shift of 90 degrees for the IQ axis.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is for inputting a first intermediate frequency signal and limiting the band thereof with a tunable band-pass filter, and selecting a station to produce a second intermediate frequency signal. Frequency converter and local oscillator, a frequency divider for inputting the signal of the local oscillator, and an I / O for quasi-synchronous detection.
A Q detection circuit and a low-pass filter for each of the IQ signals are provided. An output signal of the frequency converter is input to the IQ detection circuit, and an output signal of the frequency dividing circuit is added as a local oscillation signal of the IQ detection circuit. This is a satellite broadcast receiver that obtains an IQ signal by using a frequency divider. Signals that are 90 degrees out of phase with each other can be accurately extracted from the frequency dividing circuit, so that IQ detection with good orthogonal accuracy can be realized.

According to a second aspect of the present invention, the frequency divider for inputting the signal of the local oscillator is a quarter frequency divider, and the local oscillation frequency is set higher than the first intermediate frequency. 2. The satellite broadcast receiver according to claim 1, wherein one third of the first intermediate frequency is set to be approximately the second intermediate frequency, wherein the second intermediate frequency obtained by frequency conversion is 4% of the local oscillation frequency. The frequency becomes the same as the divided frequency, and a signal obtained from the 1/4 frequency dividing circuit can be used as a local oscillation signal of the IQ detection circuit. Since it can be extracted, IQ detection with good orthogonal accuracy can be realized.

According to a third aspect of the present invention, a variable gain amplifier capable of inputting an output of a frequency converter and varying a gain is inserted between the frequency converter and the IQ detection circuit. 2. The satellite broadcast receiver according to 2, wherein the variable gain amplifier does not cause distortion in the next stage IQ detection circuit due to excessive input.

According to a fourth aspect of the present invention, the low-pass filter is a variable-frequency low-pass filter whose cut-off frequency is controlled in accordance with a transmitted signal transmission rate. The satellite broadcast receiver according to claim 2 or 3, wherein even when the transmission rate of the received signal changes depending on the channel, the optimum reception can be performed by changing the Nyquist bandwidth.

According to a fifth aspect of the present invention, the frequency divider for inputting the signal of the local oscillator is a 1/8 frequency divider, and the local oscillation frequency is set higher than the first intermediate frequency. 2. The satellite broadcast receiver according to claim 1, wherein one seventh of the first intermediate frequency is set to be approximately the second intermediate frequency, wherein the second intermediate frequency obtained by frequency conversion is 8% of the local oscillation frequency. The frequency becomes the same as the divided frequency, and the signal obtained from the 1/8 frequency dividing circuit can be used as the local oscillation signal of the IQ detection circuit. Since it can be extracted, IQ detection with good orthogonal accuracy can be realized.

According to a sixth aspect of the present invention, the frequency divider for inputting the signal of the local oscillator is a quarter frequency divider, and the local oscillation frequency is set lower than the first intermediate frequency. 2. The satellite broadcast receiver according to claim 1, wherein one fifth of the first intermediate frequency is set to be approximately the second intermediate frequency, wherein the second intermediate frequency obtained by frequency conversion is 4% of the local oscillation frequency. The frequency becomes the same as the divided frequency, and a signal obtained from the 1/4 frequency dividing circuit can be used as a local oscillation signal of the IQ detection circuit. Since it can be extracted, IQ detection with good orthogonal accuracy can be realized.

According to a seventh aspect of the present invention, the frequency divider for inputting the signal of the local oscillator is a 1/2 frequency divider, and the local oscillation frequency is set lower than the first intermediate frequency. 2. The satellite broadcast receiver according to claim 1, wherein one third of the first intermediate frequency is set to be approximately the second intermediate frequency, wherein the second intermediate frequency obtained by frequency conversion is 2% of the local oscillation frequency. The frequency becomes the same as the divided frequency, and the signal obtained from the 1/2 frequency dividing circuit can be used as the local oscillation signal of the IQ detection circuit. Since it can be extracted, IQ detection with good orthogonal accuracy can be realized.

According to an eighth aspect of the present invention, there is provided a band-pass filter for inputting a first intermediate frequency signal to limit a band, a frequency converter for selecting a channel to produce a second intermediate frequency signal, and a local unit. An oscillator, a frequency divider for inputting a signal of the local oscillator, an IQ detector for quasi-synchronous detection,
A low-pass filter for each of the Q signals, inputting the output signal of the frequency converter to an IQ detection circuit;
A satellite broadcast receiver in which an IQ signal is obtained by adding an output signal of a frequency dividing circuit as a local oscillation signal of a Q detection circuit. A signal having a phase shift of 90 degrees with respect to each other can be accurately extracted from the frequency dividing circuit. Therefore, IQ detection with good orthogonal accuracy can be realized.

According to a ninth aspect of the present invention, the frequency divider for inputting the signal of the local oscillator is a quarter frequency divider, and the local oscillation frequency is set higher than the first intermediate frequency. 9. The satellite broadcast receiver according to claim 8, wherein one third of the first intermediate frequency is set to be approximately the second intermediate frequency, and the second intermediate frequency obtained by frequency conversion is 4% of the local oscillation frequency. The frequency becomes the same as the divided frequency, and a signal obtained from the 1/4 frequency dividing circuit can be used as a local oscillation signal of the IQ detection circuit. Since it can be extracted, IQ detection with good orthogonal accuracy can be realized.

According to a tenth aspect of the present invention, the frequency divider for inputting the signal of the local oscillator is a quarter frequency divider, and the local oscillation frequency is set lower than the first intermediate frequency. 9. The satellite broadcast receiver according to claim 8, wherein one fifth of the first intermediate frequency is set to be approximately the second intermediate frequency, and the second intermediate frequency obtained by frequency conversion is 4% of the local oscillation frequency. The frequency becomes the same as the divided frequency, and a signal obtained from the 1/4 frequency dividing circuit can be used as a local oscillation signal of the IQ detection circuit. Since it can be extracted, IQ detection with good orthogonal accuracy can be realized.

According to an eleventh aspect of the present invention, there is provided a filter for inputting a first intermediate frequency signal from a broadcasting satellite or a communication satellite, limiting a band, and selecting a channel to generate a second intermediate frequency signal. A frequency converter, a local oscillator, a frequency dividing circuit for inputting a signal of the local oscillator, an IQ detection circuit for quasi-synchronous detection, and a low-pass filter for each of the IQ signals. Output signal of IQ
An IQ signal is obtained by adding an output signal of a frequency dividing circuit as a local oscillation signal of an IQ detecting circuit to be input to a detecting circuit, and a frequency dividing circuit for inputting a signal of a local oscillator is a quarter frequency dividing circuit. When receiving a signal from a broadcasting satellite, the local oscillation frequency is set higher than the first intermediate frequency, and one third of the first intermediate frequency is approximately equal to the second intermediate frequency.
When the signal is set to have the intermediate frequency and when receiving a signal from a communication satellite, the local oscillation frequency is set to be lower than the first intermediate frequency, and one fifth of the first intermediate frequency is substantially equal to the second intermediate frequency. This is a satellite broadcast receiver set to have an intermediate frequency, and has a feature that the local oscillation frequency range required when receiving signals from broadcast satellites and communication satellites can be reduced.

According to a twelfth aspect of the present invention, a first intermediate frequency signal from a broadcasting satellite and a communication satellite is inputted from respective input terminals, and a band for a broadcasting satellite for band limiting each signal. A pass filter and a band-pass filter for a communication satellite; a frequency converter and a local oscillator for selecting a channel to generate a second intermediate frequency signal; a frequency dividing circuit for inputting a signal of the local oscillator; Detection circuit and a low-pass filter for each of the IQ signals, input the output signal of the frequency converter to the IQ detection circuit, and output the signal of the frequency division circuit as a local oscillation signal of the IQ detection circuit To obtain an IQ signal,
The frequency dividing circuit for inputting the signal of the local oscillator is a 1/4 frequency dividing circuit. When a signal from a broadcasting satellite is received, the first intermediate frequency is supplied to a frequency converter via a band pass filter for the broadcasting satellite. A signal is input, the local oscillation frequency is set higher than the first intermediate frequency, and one third of the first intermediate frequency is set to be approximately the second intermediate frequency, and a signal from a communication satellite is received. In doing so, the first intermediate frequency signal is input to the frequency converter via the band pass filter for the communication satellite, the local oscillation frequency is set lower than the first intermediate frequency, and the local oscillation frequency is set to 5 minutes of the first intermediate frequency. 1 is roughly the second
This is a satellite broadcast receiver set to have an intermediate frequency, and has a feature that the local oscillation frequency range required when receiving signals from broadcast satellites and communication satellites can be reduced.

According to a thirteenth aspect of the present invention, there is provided a switch for superimposing a first intermediate frequency signal from a broadcasting satellite and a communication satellite, inputting the signal from one input terminal, and branching the signal into two. A band-pass filter for a broadcasting satellite and a band-pass filter for a communication satellite for band-limiting each signal; a frequency converter and a local oscillator for selecting a station to produce a second intermediate frequency signal; , A frequency dividing circuit for inputting the signal, an IQ detecting circuit for quasi-synchronous detection,
A low-pass filter for each of the Q signals, inputting the output signal of the frequency converter to an IQ detection circuit;
An IQ signal is obtained by adding an output signal of a frequency dividing circuit as a local oscillation signal of a Q detection circuit, and a frequency dividing circuit for inputting a signal of a local oscillator is a 1/4 frequency dividing circuit. When receiving a signal, a first intermediate frequency signal is input to a frequency converter via a bandpass filter for a broadcasting satellite, and a local oscillation frequency is set higher than the first intermediate frequency. Is set to be approximately the second intermediate frequency, and when receiving a signal from a communication satellite, the first intermediate frequency signal is transmitted to a frequency converter via a band-pass filter for the communication satellite. And the local oscillation frequency is set to be lower than the first intermediate frequency, and is set so that one fifth of the first intermediate frequency is substantially equal to the second intermediate frequency. From communication satellite It is characterized in that the local oscillation frequency range necessary for receiving the signal can be reduced.

According to a fourteenth aspect of the present invention, there is provided the satellite broadcast receiver according to the thirteenth aspect, wherein the band-pass filter for the communication satellite is a tunable filter. Thus, there is a characteristic that distortion in a subsequent stage is less likely to occur by extracting only signals for several channels.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 1 of the present invention. The same reference numerals as in FIG. A first intermediate frequency signal of a frequency f1 input from a first intermediate frequency input terminal 1 connected to a broadcast receiving antenna is roughly selected by a tunable band-pass filter 2 after receiving a signal. , Is input to the frequency converter 4 and frequency-converted into a second intermediate frequency signal having a frequency f2.

The local oscillation signal having the frequency fL used for the frequency conversion is obtained from the local oscillator 18, and the second intermediate frequency signal frequency-converted by the frequency converter 4 is the frequency fL of the local oscillation signal of the local oscillator 18. The output signal of the 1/4 frequency dividing circuit 19 is input through the in-phase detector 12, the low-pass filter 13 and the variable gain amplifier 20 to which the output signal of the 1/4 frequency dividing circuit 19 is input. Quadrature detector 14 to which signal is input and low-pass filter 15
And via the variable gain amplifier 21 to the IQ baseband output terminals 16 and 17, respectively.

The operation of the satellite broadcast receiver according to Embodiment 1 configured as described above will be described below. A signal received by a satellite broadcast receiving antenna is input to a first intermediate frequency input terminal 1, and the first intermediate frequency signal input from the first intermediate frequency input terminal 1 is received by a tunable band-pass filter 2 to convert the received signal. After being roughly selected, it is input to the frequency converter 4 via the pre-variable attenuator 3 and frequency-converted to a second intermediate frequency signal.

At this time, the oscillation frequency fL of the local oscillator 18
Performs a so-called upper local frequency conversion of a method of setting higher than the first intermediate frequency f1. At this time, the NF at the input of the frequency converter 4 is affected by the NFs of the in-phase detector 12 and the quadrature detector 14, so that these NFs also need to be sufficiently improved.

The local oscillation signal applied to the in-phase detector 12 and the quadrature detector 14 is obtained by changing the frequency fL of the local oscillation signal of the local oscillator 18 for generating the second intermediate frequency signal to 4.
Obtained by dividing. The 1/4 frequency dividing circuit 19 is the local oscillator 1
8 is divided by four. At this time, it is easy to obtain signals that are 90 ° out of phase with each other.

An IQ detection circuit can be configured by inputting the signals that have been shifted (quadrature) by 90 degrees to the in-phase detector 12 and the quadrature detector 14. In this case, since a signal having a phase difference of 90 degrees is obtained from the digital circuit, there is an advantage that the accuracy of the phase difference is higher than a signal obtained by a filter using a conventional analog circuit.

FIG. 2 is a diagram showing a frequency relationship of a received signal of the satellite broadcast receiver according to the first embodiment. In satellite broadcasting by a broadcasting satellite, the first intermediate frequency f1 is 1.04G.
Hz to 1.33 GHz. In the conventional method of extracting and detecting one wave using a channel filter, the second intermediate frequency is constant at, for example, 402.78 MHz.

In the case of the first embodiment, as shown in FIG. 2, so-called upper local frequency conversion for setting the oscillation frequency fL of the local oscillator 18 higher than the first intermediate frequency f1 is performed, and the first intermediate frequency is converted. By setting such that one-third of the frequency f1 is substantially equal to the second intermediate frequency f2, the second intermediate frequency f2 does not become constant, but becomes 0.35G.
Hz to 0.44 GHz, and a quarter frequency divider 19 that divides the output signal of the local oscillator 18 by four.
, An IQ comprising an in-phase detector 12 and a quadrature detector 14
Since a local oscillation signal of the detection circuit can be obtained, a signal having no frequency shift and having a phase shifted by 90 degrees for the IQ axis can be accurately extracted.

In the first embodiment, a channel filter such as a surface acoustic wave filter is not used.
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 2) FIG. 3 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 2 of the present invention, and is an electrical block diagram of the satellite broadcast receiver according to Embodiment 1 described above. 1 in that a variable gain amplifier 22 is inserted between the frequency converter 4 and the in-phase detector 12 and the quadrature detector 14, and the other points are the same as those in FIG.

The operation of the satellite broadcast receiver according to Embodiment 2 configured as described above is such that the second intermediate frequency signal output from the frequency converter 4 is converted into a signal by the newly added variable gain amplifier 22. This is the same as the first embodiment except that the dynamic range of the level is compressed and input to the in-phase detector 12 and the quadrature detector 14. The newly added variable gain amplifier 22 prevents the in-phase detector 12 and quadrature detector 14 at the next stage from being distorted due to excessive input.

Further, the frequency relationship of the received signal of the satellite broadcast receiver according to the second embodiment is as shown in the frequency relationship diagram of FIG. 2, and the oscillation frequency fL of the local oscillator 18 is set higher than the first intermediate frequency f1. By performing a so-called upper local frequency conversion that is set to a high value and setting one third of the first intermediate frequency f1 to be approximately the second intermediate frequency f2, the second intermediate frequency f2 is not constant. Without
This changes from 0.35 GHz to 0.44 GHz, and the local oscillation of the IQ detection circuit including the in-phase detector 12 and the quadrature detector 14 from the １ ／ frequency divider 19 that divides the output signal of the local oscillator 18 by four. Since a signal is obtained, a signal having no frequency shift and having a phase shift of 90 degrees for the IQ axis can be accurately extracted.

In the first embodiment, a channel filter such as a surface acoustic wave filter is not used.
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 3) An electric block diagram of a satellite broadcast receiver according to Embodiment 3 of the present invention is the same as that of FIG. 3 which is an electric block diagram of the satellite broadcast receiver according to Embodiment 2. However, the low-pass filters 13 and 15 shown in FIG. 3 are variable frequency low-pass filters whose cutoff frequencies are controlled in accordance with the signal transmission rate.

Since the occupied bandwidth of the transmitted signal changes when the transmission rate of the received signal changes depending on the channel, the Nyquist bandwidth of the demodulator is changed by changing the bandwidth of the low-pass filter. The operation is the same as that in the above-described second embodiment except that optimum reception becomes possible.

(Embodiment 4) FIG. 4 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 4 of the present invention, and is an electrical block diagram of the satellite broadcast receiver according to Embodiments 2 and 3. 3 differs from FIG. 3 in that a 1/8 frequency divider 23 is used instead of the 1/4 frequency divider 19 in FIG.
The other points are the same as those in FIG.

The operation of the satellite broadcast receiver according to the fourth embodiment configured as described above is such that the second intermediate frequency signal frequency-converted by the frequency converter 4 is changed to the frequency fL of the local oscillation signal of the local oscillator 18. 1/8 frequency dividing circuit 2 for dividing frequency by 8
3 through the in-phase detector 12 and the low-pass filter 13 and the variable gain amplifier 20 to which the output signal of the １ ／ frequency divider circuit 23 has been input. It is the same as the satellite broadcast receiver according to Embodiments 2 and 3 shown in FIG. 3 except that the signals are output to IQ baseband output terminals 16 and 17 via a low-pass filter 15 and a variable gain amplifier 21, respectively.

FIG. 5 is a diagram showing the frequency relationship of the received signal of the satellite broadcast receiver according to the fourth embodiment.
So-called upper local frequency conversion for setting the oscillating frequency fL higher than the first intermediate frequency f1, and
One seventh of the first intermediate frequency f1 is substantially equal to the second intermediate frequency f
2 so that the second intermediate frequency f
2 is not constant, but from 0.15 GHz to 0.19 GH
z, and the local oscillation signal of the IQ detection circuit including the in-phase detector 12 and the quadrature detector 14 can be obtained from the 1/8 frequency divider 23 that divides the output signal of the local oscillator 18 by 8. A signal having no frequency shift and having a 90-degree phase shift for the IQ axis can be accurately extracted.

In the fourth embodiment, a channel filter such as a surface acoustic wave filter is not used.
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

Further, according to the fourth embodiment, the change of the second intermediate frequency f2 is reduced as compared with the first, second, and third embodiments, so that the accuracy of the 90-degree phase shift is higher. Further, since the frequency is lowered, it is more suitable for IC.

(Embodiment 5) The electrical block diagram of the satellite broadcast receiver according to Embodiment 5 of the present invention is the same as that of FIG. 3 which is the electrical block diagram of the satellite broadcast receiver according to Embodiments 2 and 3. The operation is basically the same as that of FIG.
However, as shown in the frequency relationship diagram of FIG. 6, the frequency relationship of the received signal of the satellite broadcast receiver in the fifth embodiment is such that the oscillation frequency fL of the local oscillator 18 is higher than the first intermediate frequency f1. The second intermediate frequency f2 is kept constant by performing so-called lower local frequency conversion, which is set low, and setting such that one fifth of the first intermediate frequency f1 is substantially equal to the second intermediate frequency f2. Not 0.2
Will change from 1 GHz to 0.27 GHz,
Since a local oscillation signal of an IQ detection circuit including an in-phase detector 12 and a quadrature detector 14 can be obtained from a 1/4 frequency dividing circuit 19 which divides the output signal of the local oscillator 18 by 4, there is no frequency shift and IQ It is possible to accurately extract a signal shifted by 90 degrees for the axis.

In the fifth embodiment, a channel filter such as a surface acoustic wave filter is not used.
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 6) FIG. 7 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 6 of the present invention, and is an electrical block diagram of the satellite broadcast receiver according to Embodiments 2 and 3. 3 is different from FIG. 3 in that a 1/2 frequency dividing circuit 24 is used instead of the 1/4 frequency dividing circuit 19 in FIG.
The other points are the same as FIG. 3,
The operation is basically the same as that of FIG. 3, but the frequency relationship of the received signal of the satellite broadcast receiver in the sixth embodiment is, as shown in the frequency relationship diagram of FIG. A so-called lower local frequency conversion for setting fL lower than the first intermediate frequency f1 is performed, and one third of the first intermediate frequency f1 is substantially equal to the second intermediate frequency f2.
By setting so that the second intermediate frequency f2
Is not constant, but 0.35 GHz to 0.44 GHz
Will change to

Among the master-slave type flip-flops used in the frequency-dividing circuit, the slave-side flip-flop output and the master-side flip-flop output are:
Since the signals are phase-shifted by 90 degrees with respect to each other with high accuracy, if this signal is input to an IQ detection circuit, IQ detection with good quadrature accuracy can be realized.

That is, the output signal of the local oscillator 18 is set to 2
Since a local oscillation signal of the IQ detection circuit including the in-phase detector 12 and the quadrature detector 14 can be obtained from the 1/2 frequency dividing circuit 24 that divides the frequency, there is no frequency shift, and a 90-degree phase shift for the IQ axis occurs. The extracted signal can be accurately extracted. In the sixth embodiment, since a channel filter such as a surface acoustic wave filter is not used, the frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 7) FIG. 9 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 7 of the present invention, and is an electrical block diagram of the satellite broadcast receiver according to Embodiment 2 of the present invention. The difference from FIG. 3 is that a bandpass filter 53 is used instead of the variable tuning bandpass filter, and the other points are the same as FIG.

The operation of the satellite broadcast receiver according to the seventh embodiment configured as described above
Therefore, a maximum of eight signals usable in the broadcasting satellite are applied to the circuits after the pre-variable attenuator 3.
Therefore, it is necessary to enhance the distortion characteristics of the circuit at the subsequent stage as compared with the case of using a tunable band-pass filter. However, in the case of a broadcasting satellite, the maximum number is eight waves, which is not a severe requirement. On the other hand, the band-pass filter 53 used for band limitation has a simple configuration in which the pass band is from 1.04 GHz to 1.33 GHz, which is the first intermediate frequency band of the broadcasting satellite, and is easily formed using a strip line or the like. Can be configured. Since such a band-pass filter 53 is used, there is an advantage that the design is easy, the stability is high, and the configuration can be performed at a low cost, as compared with a tunable band-pass filter.

Further, the frequency relationship of the received signal of the satellite broadcast receiver according to the seventh embodiment is as shown in the frequency relationship diagram of FIG. 2, and the oscillation frequency fL of the local oscillator 18 is higher than the first intermediate frequency f1. By performing a so-called upper local frequency conversion that is set to a high value and setting one third of the first intermediate frequency f1 to be approximately the second intermediate frequency f2, the second intermediate frequency f2 is not constant. Without
This changes from 0.35 GHz to 0.44 GHz, and the local oscillation of the IQ detection circuit including the in-phase detector 12 and the quadrature detector 14 from the １ ／ frequency divider 19 that divides the output signal of the local oscillator 18 by four. Since a signal is obtained, a signal having no frequency shift and having a phase shift of 90 degrees for the IQ axis can be accurately extracted.

In the seventh embodiment, a channel filter such as a surface acoustic wave filter is not used.
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Eighth Embodiment) An electric block diagram of a satellite broadcast receiver according to an eighth embodiment of the present invention is the same as FIG. 9 which is an electric block diagram of the satellite broadcast receiver according to the seventh embodiment. However, the difference is that the pass band width of the band-pass filter 53 changes from 1.52 GHz which is the first intermediate frequency from the communication satellite to 2.07 GHz as shown in FIG. Is the same as The local oscillation frequency of the LNB for receiving communication satellites is 10.678 GHz which is adopted for receiving broadcast satellites.
It has been adopted.

The operation of the satellite broadcast receiver according to the eighth embodiment configured as described above is based on the operation of the band-pass filter 53.
Therefore, all signals usable in the communication satellite are applied to the circuits after the variable attenuator 3. Therefore, compared to using a tunable bandpass filter,
It is necessary to enhance the distortion characteristics for the subsequent circuit.

A 550 MHz band is allocated to the communication satellite. For this reason, assuming that the bandwidth of the repeater used for digital satellite broadcasting is 36 MHz, the maximum is about 14 waves. In this case, the distortion characteristic is severer than eight satellite broadcast waves. However, in digital transmission, the detection limit of interference is equivalently regarded as C / N degradation, and is considered to be approximately 14 dB compared to 31 dB of analog transmission. Therefore, distortion characteristics of the entire system can be reduced.

Therefore, the requirements are not so severe.
On the other hand, the band-pass filter 53 used for band limitation has a simple configuration having a pass band from 1.52 GHz to 2.07 GHz, which is the first intermediate frequency band of the communication satellite, and can be easily formed by using a strip line or the like. Can be configured.
Since such a band-pass filter 53 is used, there is an advantage that the design is easy, the stability is high, and the configuration can be performed at a low cost, as compared with a tunable band-pass filter.

Further, the frequency relationship of the received signal of the satellite broadcast receiver according to the seventh embodiment is as shown in the frequency relationship diagram of FIG. 10, and the oscillation frequency fL of the local oscillator 18 is higher than the first intermediate frequency f1. A so-called upper local frequency conversion that is set high is performed, and the first intermediate frequency f1 is set.
Is set to be approximately the second intermediate frequency f2, the second intermediate frequency f2 is not constant, but changes from 0.30 GHz to 0.41 GHz. Divides the output signal by 4 by 1 /
The in-phase detector 12 and the quadrature detector 1
Since the local oscillation signal of the IQ detection circuit consisting of No. 4 is obtained, it is possible to accurately extract a signal shifted by 90 degrees for the IQ axis without frequency shift.

In the eighth embodiment, since a channel filter such as a surface acoustic wave filter is not used,
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 9) FIG. 11 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 9 of the present invention, and is an electrical block diagram of the satellite broadcast receiver according to Embodiment 2 of the present invention. 3 is different from the first intermediate frequency of 1.52 GHz when the pass band of the tunable band-pass filter 2 receives a signal from the communication satellite (CS) as shown in FIG. It is controlled at 0.07 GHz.

When a signal from a broadcasting satellite (BS) is received, its first intermediate frequency of 1.04 GHz
From 1.3 to 1.33 GHz. It is assumed that the local oscillation frequency of the LNB for receiving communication satellites is 10.678 GHz which is used for receiving broadcast satellites.

The operation of the satellite broadcast receiver according to the ninth embodiment configured as described above, when receiving a signal from a broadcast satellite, is the same as the operation described in the second embodiment. When receiving a signal from the communication satellite applied to the input terminal 1 of the same first intermediate frequency signal, the signal passes through the tunable bandpass filter 2 in conjunction with the frequency of the local oscillator 18 as described above. The band is 1.52 GHz to 2.07 GHz, which is the first intermediate frequency as shown in FIG.
Is controlled. That is, the frequency relationship of the received signal of the satellite broadcast receiver according to the ninth embodiment is as shown in the frequency relationship diagram in the case of CS in FIG. 12, and the oscillation frequency fL of the local oscillator 18 is higher than the first intermediate frequency f1. A so-called upper local frequency conversion that is set high is performed, and one third of the first intermediate frequency f1 is substantially equal to the second intermediate frequency f2.
By setting so that the second intermediate frequency f2
Is not constant, but 0.30 GHz to 0.41 GHz
Since the local oscillation signal of the IQ detection circuit including the in-phase detector 12 and the quadrature detector 14 can be obtained from the 分 frequency dividing circuit 19 which divides the output signal of the local oscillator 18 by four, It is possible to accurately extract a signal having no shift and a phase shift of 90 degrees for the IQ axis.

In the ninth embodiment, a channel filter such as a surface acoustic wave filter is not used.
The frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

The signals from the broadcasting satellite and the communication satellite superimposed on one signal line in this way are controlled in conjunction with the frequency of the local oscillator 18 and the pass band of the tunable band-pass filter 2, whereby It is possible to realize a satellite broadcast receiver capable of switching and receiving.

(Embodiment 10) FIG. 13 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 10 of the present invention, and is an electrical block diagram of a satellite broadcast receiver according to Embodiment 9 of the present invention. 11 is different from the first embodiment in that a common first intermediate frequency input terminal 1 and a tunable bandpass filter 2 from a broadcasting satellite and a communication satellite are connected to a first intermediate frequency input terminal 51 from a broadcasting satellite and a second An input terminal 52 for one intermediate frequency and a band pass filter 53 for a first intermediate frequency signal from a broadcasting satellite and a band pass filter 54 for a first intermediate frequency signal from a communication satellite are replaced. .

As shown in FIG. 12, the band of the band-pass filter 54 is 1.52 GHz to 2.07 GHz which is the first intermediate frequency for receiving a signal from the communication satellite (CS). And the bandpass filter 53
In order to receive a signal from a broadcasting satellite (BS), the band from 1.04 GHz which is the first intermediate frequency is 1.
33 GHz. The local oscillation frequency of the LNB for receiving communication satellites is adopted for receiving broadcast satellites.
678 GHz is adopted. Other parts are the same as those in FIG.

The tenth embodiment configured as described above
The operation of the satellite broadcast receiver in
By 3 to 54, the first intermediate frequency from the broadcasting satellite or the communication satellite is band-limited and extracted, and the subsequent signal processing is performed. At this time, there is no need to switch the signals from the broadcast satellite and the communication satellite, and the frequency of the local oscillator 18 may be set to tune to the signal to be received.

At this time, since all signals from the broadcasting satellite and the communication satellite are applied to the subsequent stage, a signal of up to about 22 waves is inputted, and the distortion characteristics of the subsequent stage need to be considerably strengthened. For this purpose, although not explicitly shown in the drawings, it is sufficient to cut off only those not using the power source of the converter for converting the radio wave from the satellite to generate the first intermediate frequency signal. In this way, only the signals of the satellite to be received are input terminals 51, 5 of the receiver.
2, the demand for distortion characteristics can be reduced.

The frequency relationship of the received signal of the satellite broadcast receiver in the tenth embodiment is as shown in the frequency relationship diagram of FIG.
By performing so-called upper local frequency conversion in which L is set higher than the first intermediate frequency f1, and setting one third of the first intermediate frequency f1 to be approximately the second intermediate frequency f2, (2) The intermediate frequency f2 is not constant but changes from 0.35 GHz to 0.44 GHz, and the output signal of the local oscillator 18 is divided by four.
Since the local oscillation signal of the IQ detection circuit composed of the in-phase detector 12 and the quadrature detector 14 can be obtained from the / 4 frequency divider 19, there is no frequency shift, and the 90-degree phase-shifted signal for the IQ axis can be accurately converted. Can be taken out well.

In the tenth embodiment, since a channel filter such as a surface acoustic wave filter is not used, the frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 11) FIG. 14 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 11 of the present invention, and is an electrical block diagram of a satellite broadcast receiver according to Embodiment 9 of the present invention. 11 is different from the tunable band-pass filter 2 in that a tunable band-pass filter 2 receives a first intermediate frequency signal from a broadcasting satellite or a communication satellite and switches between the first intermediate frequency signal and a first intermediate frequency signal from the broadcasting satellite. The bandpass filter 53 and the bandpass filter 54 for the first intermediate frequency signal from the communication satellite are replaced.

The band of the band-pass filter 54 is 1.52 GHz to 2.07 GHz which is the first intermediate frequency for receiving a signal from the communication satellite (CS) as shown in FIG. And the bandpass filter 53
In order to receive a signal from a broadcasting satellite (BS), the band from 1.04 GHz which is the first intermediate frequency is 1.
33 GHz.

The local oscillation frequency of the LNB for receiving communication satellites is 10.678 which is adopted for receiving broadcast satellites.
GHz is adopted. Other parts are the same as those in FIG.

The twelfth embodiment configured as described above
The operation of the satellite broadcast receiver in
By 3 to 54, the first intermediate frequency from the broadcasting satellite or the communication satellite is band-limited and extracted, and the subsequent signal processing is performed. At this time, signals from the broadcasting satellite and the communication satellite are switched by the switch 56.

When receiving a signal from a broadcasting satellite, the first intermediate frequency signal from the broadcasting satellite passes through the band-pass filter 53 and is applied to the subsequent stage. Therefore, a signal having a maximum of eight waves is applied, so that a strong distortion characteristic is not required. When a signal from the communication satellite is received, the first intermediate frequency signal from the communication satellite passes through the band-pass filter 54 and is applied to the subsequent stage. It is applied to the circuit after the variable attenuator 3.

For this reason, it is necessary to enhance the distortion characteristics with respect to the circuit at the subsequent stage as compared with the case where the variable tuning band pass filter is used. The communication satellite is assigned a 550 MHz band. For this reason, assuming that the bandwidth of the repeater used for digital satellite broadcasting is 36 MHz, the maximum is about 14 waves. In this case, the distortion characteristic is severer than eight satellite broadcast waves. However, in digital transmission, the detection limit of disturbance is equivalently regarded as C / N deterioration,
Since it is considered to be about 14 dB compared to 31 dB of the analog transmission, the distortion characteristics of the entire system can be reduced. Therefore, it is not so demanding.

On the other hand, the band-pass filter 53 used for band limitation is the first intermediate frequency band 1.5 of the communication satellite.
It has a simple configuration with a pass band from 2 GHz to 2.07 GHz, and can be easily configured using a strip line or the like. Since such a band-pass filter 54 is used, there are advantages in that the design is easier, the stability is higher, and the configuration can be made at a lower cost as compared with a tunable band-pass filter.

The frequency relationship of the received signal of the satellite broadcast receiver in the eleventh embodiment is as shown in the frequency relationship diagram of FIG.
By performing so-called upper local frequency conversion in which L is set higher than the first intermediate frequency f1, and setting one third of the first intermediate frequency f1 to be approximately the second intermediate frequency f2, (2) The intermediate frequency f2 is not constant but changes from 0.35 GHz to 0.44 GHz, and the output signal of the local oscillator 18 is divided by four.
Since the local oscillation signal of the IQ detection circuit composed of the in-phase detector 12 and the quadrature detector 14 can be obtained from the / 4 frequency divider 19, there is no frequency shift, and the 90-degree phase-shifted signal for the IQ axis can be accurately converted. Can be taken out well.

In the tenth embodiment, since a channel filter such as a surface acoustic wave filter is not used, the frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

(Embodiment 12) FIG. 15 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 12 of the present invention, and is an electrical block diagram of the satellite broadcast receiver according to Embodiment 11 of the present invention. The difference from 14 is that the bandpass filter 54 is replaced by a tunable bandpass filter 57 for the first intermediate frequency signal from the communication satellite.

The pass band of the tunable band pass filter 57 is the first intermediate frequency for receiving a signal from the communication satellite (CS) as shown in FIG.
It is controlled from 52 GHz to 2.07 GHz. The band of the band-pass filter 53 is the first intermediate frequency for receiving a signal from a broadcasting satellite (BS).
It is from 04 GHz to 1.33 GHz.

The local oscillation frequency of the LNB for receiving communication satellites is 10.678 which is adopted for receiving broadcast satellites.
GHz is adopted. Other parts are the same as those in FIG.

The twelfth embodiment configured as described above
The operation of the satellite broadcast receiver in
3 and a variable tuning band-pass filter 57 for band-limiting and extracting the first intermediate frequency from a broadcasting satellite or a communication satellite, and performs signal processing at a subsequent stage. At this time, signals from the broadcasting satellite and the communication satellite are
Can be switched.

When receiving a signal from a broadcasting satellite, the first intermediate frequency signal from the broadcasting satellite passes through the band-pass filter 53 and is applied to the subsequent stage. Therefore, a signal having a maximum of eight waves is applied, so that a strong distortion characteristic is not required. When a signal from a communication satellite is received, the first intermediate frequency signal from the communication satellite passes through the tunable bandpass filter 57 and is applied to the subsequent stage, so that only a few waves near the received signal are received. And does not require as strong a distortion characteristic as BS.

The frequency relationship of the received signal of the satellite broadcast receiver according to the twelfth embodiment is as shown in the frequency relationship diagram of FIG.
By performing so-called upper local frequency conversion in which L is set higher than the first intermediate frequency f1, and setting one third of the first intermediate frequency f1 to be approximately the second intermediate frequency f2, (2) The intermediate frequency f2 is not constant but changes from 0.35 GHz to 0.44 GHz, and the output signal of the local oscillator 18 is divided by four.
Since the local oscillation signal of the IQ detection circuit composed of the in-phase detector 12 and the quadrature detector 14 can be obtained from the / 4 frequency divider 19, there is no frequency shift, and the 90-degree phase-shifted signal for the IQ axis can be accurately converted. Can be taken out well.

In the tenth embodiment, since a channel filter such as a surface acoustic wave filter is not used, the frequency may change. Therefore, the receiving circuit can be simplified, and the cost can be reduced.

[0085]

As described above, according to the present invention, the IQ signal is obtained as the local oscillation signal of the IQ detection circuit by dividing the frequency of the local oscillator signal for producing the second intermediate frequency signal. Therefore, a local oscillator or a phase shifter for IQ detection is not required, the configuration is simple, and a channel filter using a surface acoustic wave filter or the like is not required. A satellite broadcast receiver can be realized.

[Brief description of the drawings]

FIG. 1 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 1 of the present invention.

FIG. 2 is a frequency relationship diagram of a received signal of a satellite broadcast receiver according to the first and second embodiments of the present invention.

FIG. 3 is an electrical block diagram of a satellite broadcast receiver according to Embodiments 2, 3, and 5 of the present invention.

FIG. 4 is an electrical block diagram of a satellite broadcast receiver according to a fourth embodiment of the present invention.

FIG. 5 is a diagram illustrating a frequency relationship of a received signal of a satellite broadcast receiver according to a fourth embodiment of the present invention.

FIG. 6 is a frequency relation diagram of a received signal of a satellite broadcast receiver according to a fifth embodiment of the present invention.

FIG. 7 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 6 of the present invention.

FIG. 8 is a diagram showing a frequency relationship of a received signal of a satellite broadcast receiver according to a sixth embodiment of the present invention.

FIG. 9 is an electrical block diagram of a satellite broadcast receiver according to a seventh embodiment of the present invention.

FIG. 10 is a diagram illustrating a frequency relationship of a received signal of a satellite broadcast receiver according to an eighth embodiment of the present invention.

FIG. 11 is an electrical block diagram of a satellite broadcast receiver according to a ninth embodiment of the present invention.

FIG. 12 is a diagram illustrating a frequency relationship of a received signal of a satellite broadcast receiver according to Embodiment 9 of the present invention.

FIG. 13 is an electrical block diagram of a satellite broadcast receiver according to a tenth embodiment of the present invention.

FIG. 14 is an electrical block diagram of a satellite broadcast receiver according to Embodiment 11 of the present invention.

FIG. 15 is an electrical block diagram of a satellite broadcast receiver according to a twelfth embodiment of the present invention.

FIG. 16 is an electrical block diagram of a conventional satellite broadcast receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st intermediate frequency input terminal 2 Variable tuning band pass filter 3 Pre-variable attenuator 4 Frequency converter 5 2nd intermediate frequency local oscillator 6 PLL frequency synthesizer 7 Variable gain amplifier 8 Channel filter 10, 18 Local oscillator 11 90 degree shift Phaser 12 In-phase detector 13, 15 Low-pass filter 14 Quadrature detector 16, 17 IQ baseband output terminal 19 1/4 frequency divider 20, 21, 22 Variable gain amplifier 23 1/8 frequency divider 24 1 / Dividing-by-2 circuit 53, 54 Band-pass filter 56 Switch 57 Variable tuning band-pass filter

Claims (14)

[Claims] 1. A tunable band-pass filter for inputting a first intermediate frequency signal to limit a band, a frequency converter and a local oscillator for selecting a channel to generate a second intermediate frequency signal, and a signal of the local oscillator. , An IQ detection circuit for quasi-synchronous detection, and a low-pass filter for each of the IQ signals.
A satellite broadcast receiver which inputs to a Q detection circuit and adds an output signal of a frequency dividing circuit as a local oscillation signal of the IQ detection circuit to obtain an IQ signal. 2. A frequency dividing circuit for inputting a signal of a local oscillator is a quarter frequency dividing circuit. The local oscillation frequency is set higher than the first intermediate frequency, and one third of the first intermediate frequency is set to one third. The satellite broadcast receiver according to claim 1, wherein the satellite broadcast receiver is set to be approximately the second intermediate frequency. 3. The satellite broadcast receiver according to claim 1, wherein a variable gain amplifier capable of inputting an output of the frequency converter and varying a gain is inserted between the frequency converter and the IQ detection circuit. 4. The satellite according to claim 1, wherein the low-pass filter is a variable-frequency low-pass filter whose cut-off frequency is controlled in accordance with a transmitted signal transmission rate. Broadcast receiver. 5. A frequency divider circuit for inputting a signal of a local oscillator is a 1/8 frequency divider circuit. The local oscillation frequency is set higher than the first intermediate frequency, and one seventh of the first intermediate frequency is used. The satellite broadcast receiver according to claim 1, wherein the satellite broadcast receiver is set to be approximately the second intermediate frequency. 6. A frequency dividing circuit for inputting a signal of a local oscillator is a quarter frequency dividing circuit, wherein a local oscillation frequency is set lower than a first intermediate frequency, and one fifth of the first intermediate frequency is set to be 1/5. The satellite broadcast receiver according to claim 1, wherein the satellite broadcast receiver is set to be approximately the second intermediate frequency. 7. A frequency dividing circuit for inputting a signal of a local oscillator is a 1/2 frequency dividing circuit, wherein the local oscillation frequency is set lower than the first intermediate frequency, and one third of the first intermediate frequency is set to be less than one third. The satellite broadcast receiver according to claim 1, wherein the satellite broadcast receiver is set to be approximately the second intermediate frequency. 8. A band-pass filter for inputting a first intermediate frequency signal to limit a band, a frequency converter and a local oscillator for selecting a channel to generate a second intermediate frequency signal, and inputting a signal of the local oscillator. A frequency divider, an IQ detector for quasi-synchronous detection, and a low-pass filter for each of the IQ signals. The output signal of the frequency converter is input to the IQ detector, and the IQ detector A satellite broadcast receiver in which an IQ signal is obtained by adding an output signal of a frequency dividing circuit as a local oscillation signal. 9. A frequency dividing circuit for inputting a signal of a local oscillator is a quarter frequency dividing circuit, wherein the local oscillation frequency is set higher than the first intermediate frequency, and one third of the first intermediate frequency is set. The satellite broadcast receiver according to claim 8, wherein the satellite broadcast receiver is set to be approximately the second intermediate frequency. 10. A frequency dividing circuit for inputting a signal of a local oscillator is a quarter frequency dividing circuit. The local oscillation frequency is set lower than the first intermediate frequency, and the local oscillation frequency is set to 5% of the first intermediate frequency.
9. The satellite broadcast receiver according to claim 8, wherein one-half is set to be approximately the second intermediate frequency. 11. The first broadcast satellite or communication satellite
A filter for inputting an intermediate frequency signal to limit a band, a frequency converter and a local oscillator for selecting a station to generate a second intermediate frequency signal, a frequency dividing circuit for inputting the signal of the local oscillator, and a quasi-synchronous circuit. An IQ detection circuit for detection, and a low-pass filter for each of the IQ signals are provided, an output signal of the frequency converter is input to the IQ detection circuit, and a local oscillation signal of the IQ detection circuit is output from the frequency dividing circuit. An IQ signal is obtained by adding an output signal, and a frequency dividing circuit for inputting a signal of a local oscillator is a 1/4 frequency dividing circuit. When a signal from a broadcast satellite is received, the local oscillation frequency is The first intermediate frequency is set to be higher than the first intermediate frequency, and one third of the first intermediate frequency is set to be approximately the second intermediate frequency. When a signal from a communication satellite is received, the local oscillation frequency is 1st middle As well as lower than the wave number, satellite receiver one-fifth of the first intermediate frequency is set to be substantially a second intermediate frequency. 12. A bandpass filter for a broadcasting satellite and a bandpass filter for a communication satellite for inputting first intermediate frequency signals from a broadcasting satellite and a communication satellite from respective input terminals and band limiting the respective signals. A frequency converter and a local oscillator for selecting a station to produce a second intermediate frequency signal,
A frequency divider circuit for inputting the signal of the local oscillator, an IQ detection circuit for quasi-synchronous detection, and a low-pass filter for each of the IQ signals are provided, and an output signal of the frequency converter is input to the IQ detection circuit. In addition, an IQ signal is obtained by adding an output signal of a frequency dividing circuit as a local oscillation signal of an IQ detection circuit, and a frequency dividing circuit for inputting a signal of a local oscillator is a 1/4 frequency dividing circuit. When receiving a signal from a satellite, the first intermediate frequency signal is input to the frequency converter via a bandpass filter for a broadcast satellite, and the local oscillation frequency is set higher than the first intermediate frequency. 1
When one-third of the intermediate frequency is set to be approximately the second intermediate frequency, and when receiving a signal from a communication satellite,
A first intermediate frequency signal is input to a frequency converter via a bandpass filter for a communication satellite, the local oscillation frequency is set lower than the first intermediate frequency, and one fifth of the first intermediate frequency is roughly equal to the first intermediate frequency. (2) A satellite broadcast receiver set to have an intermediate frequency. 13. A first intermediate frequency signal from a broadcasting satellite and a communication satellite is superimposed and input from one input terminal, and a switch for branching the signal into two is provided, and a broadcast for band limiting each signal is provided. A band-pass filter for a satellite and a band-pass filter for a communication satellite, a frequency converter and a local oscillator for selecting and generating a second intermediate frequency signal, and a frequency divider circuit for inputting a signal of the local oscillator; An IQ detection circuit for quasi-synchronous detection, and a low-pass filter for each of the IQ signals, an output signal of the frequency converter is input to the IQ detection circuit, and frequency division is performed as a local oscillation signal of the IQ detection circuit. The IQ signal is obtained by adding the output signal of the circuit, and the frequency dividing circuit for inputting the signal of the local oscillator is 1 /
When a signal from a broadcasting satellite is received, a first intermediate frequency signal is input to a frequency converter via a bandpass filter for the broadcasting satellite, and the local oscillation frequency is set to the first oscillation frequency.
The frequency is set to be higher than the intermediate frequency, and one third of the first intermediate frequency is set to be approximately the second intermediate frequency. When a signal from the communication satellite is received, the band pass for the communication satellite is used. The first intermediate frequency signal is input to the frequency converter via the filter, the local oscillation frequency is set lower than the first intermediate frequency, and one fifth of the first intermediate frequency is substantially equal to the second intermediate frequency. Set the satellite receiver to. 14. The satellite broadcast receiver according to claim 13, wherein the band-pass filter for the communication satellite is a tunable filter.