JPH04306994A - Satellite broadcast receiver - Google Patents

Abstract

PURPOSE:To simplify each image filter of the satellite broadcast receiver in which an image frequency band of a CS broadcast and an image frequency band of a BS broadcast are adjoin each other. CONSTITUTION:The satellite broadcast receiver is provided with a 1st high pass filter 90 attenuating a signal whose frequency is lower than a signal band of a 1st intermediate frequency band of a BS broadcast and passing a signal whose frequency is 1035.98-1331.5MHz being the 1st intermediate frequency band of the BS broadcast, an amplifier circuit 91, a high pass filter 43 attenuating a signal of a frequency band lower than the 1st intermediate frequency band of the CS broadcast and eliminating a signal whose frequency is 1309.75MHz 1548MHz being the 1st intermediate frequency of the CS broadcast, its amplifier circuit 96, a high frequency changeover circuit selecting an output of the amplifier circuits 91,92, and a common image filter 94 eliminating an image frequency component being a sum of the 1st intermediate frequency and a twice of the 2nd intermediate frequency so as to eliminate image disturbance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to distribution and broadcasting of television signals by communication satellites and to BS receivers.

0002

[Prior Art] In recent years, services using communication satellites (CS) have been expanding, and since CS broadcasting using communication satellites (CS) and BS are both transmitted using satellites, they are integrated. , a receiver that can enjoy both media is conceivable. 12GHz emitted from broadcasting satellites
After converging the band radio waves with a parabolic antenna, the frequency is converted to the first intermediate frequency of the 1 GHz band using a low-noise converter, and the signal is input to an indoor satellite broadcast receiver via a coaxial cable to receive satellite broadcasts. be able to. A satellite broadcasting receiver selects one signal from among several channels.
After selecting a channel, FM demodulation is performed to obtain a video signal and an audio signal.

A conventional example will be explained below with reference to the drawings. FIG. 5 shows an example of a block diagram of a conventional satellite broadcast receiver that integrates a BS receiver and a CS broadcast receiver. In FIG. 5, 211 is the first BS
This is an input terminal for intermediate frequency signals. 212 is the first BS
1035.98 which is a lower frequency band than the intermediate frequency band
This is a first high-pass filter that attenuates signals of MHz or lower and passes signals of 1035.98 MHz to 1331.5 MHz, which is the first intermediate frequency band of the BS. 213
is an amplifier circuit that amplifies the signal in the first intermediate frequency band of the BS, and 214 is an image frequency band component 183 that is the sum of twice the first intermediate frequency and the second intermediate frequency of the BS.
This is the first image filter for removing frequencies from 5 MHz to 2131.5 MHz to prevent image disturbance from occurring. 215 is a high frequency switching circuit that switches between the first intermediate frequency band of BS and the first intermediate frequency band of CS broadcasting. 2
16 is an output terminal.

Reference numeral 217 is an input terminal for a first intermediate frequency signal of CS broadcasting. 218 attenuates signals below 1309.75 MHz, which is a frequency band lower than the first intermediate frequency band of CS broadcasting, and 1, which is the first intermediate frequency band of CS broadcasting.
This is a second high-pass filter that passes signals of 309.75 MHz to 1548 MHz. 219 is an amplification circuit that amplifies the signal in the first intermediate frequency band of CS broadcasting;
220 is an image frequency band component 2109. which is the sum of double the first intermediate frequency and the second intermediate frequency of CS broadcasting.
This is a second image filter that removes frequencies from 75 MHz to 2348 MHz to prevent image interference from occurring (Reference: Satellite Broadcasting Receiver Part 1, Target Ratings, published by Radio Technology Association).

The operation of the input circuit of the satellite broadcasting receiver configured as described above will be explained. To the input terminal 211 of the first intermediate frequency signal of the BS, a 12 GHz band radio wave received by an antenna from a satellite is frequency-converted to a 1 GHz band by a down converter, and is guided indoors via a coaxial cable and applied. BS specifies that the local oscillation frequency of the down converter is 10.678 GHz. Therefore, the first intermediate frequency band of BS is 1035.98MH
z~1331.5MHz. The first high-pass filter 212 attenuates signals below 1035 MHz, which is a frequency band lower than the first intermediate frequency band. The BS first intermediate frequency amplification circuit 213 is a wideband amplification circuit that improves the NF of a mixer circuit or the like connected to the subsequent stage. The first image filter 214 has an image frequency band of 1850 to 234, which is the sum of the first intermediate frequency of the BS and twice the second intermediate frequency, in order to prevent image interference from occurring.
It plays a role in removing 8MHz signals. A 12 GHz band radio wave from a satellite received by an antenna is frequency-converted to a 1 GHz band by a down converter, and is guided indoors via a coaxial cable and applied to the input terminal 217 of the first intermediate frequency signal of the CS. In CS broadcasting, it is specified that the local oscillation frequency of the down converter is 11.2 GHz. Therefore, the first intermediate frequency band of CS broadcasting is 1309.75 MHz to 1548 MHz.

[0006] The second high-pass filter 218 has a frequency band 1309 lower than the first intermediate frequency band of CS broadcasting.
．． Attenuates signals below 75MHz. The CS broadcast first intermediate frequency amplification circuit 219 is a wideband amplification circuit that improves the NF of a mixer circuit or the like connected to the subsequent stage. The second image filter 220 has an image frequency band of 2115.2, which is the sum of the first intermediate frequency and twice the second intermediate frequency of CS broadcasting, in order to prevent image interference from occurring.
It plays a role in removing signals from 31 MHz to 2353.56 MHz. The high frequency switching circuit 215
The first intermediate frequency band of 1035.98MHz to 1331MHz
．． 5MHz, and the first intermediate frequency band of CS broadcasting is 13
09.75 MHz to 1548 MHz, and since there is a frequency where the first intermediate frequency band of BS and the first intermediate frequency band of CS broadcasting overlap, it plays a role in switching between BS and CS broadcasting.

[0007]

As described above, the image frequency band of CS broadcasting and the image frequency band of BS are adjacent to each other, and a satellite broadcasting receiver with simplified image filters for each can be considered.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to simplify image filters for CS broadcasting and BS broadcasting in a satellite broadcasting receiver.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the satellite broadcasting receiver of the present invention attenuates signals below 1309.75 MHz, which is a frequency band lower than the first intermediate frequency band of CS broadcasting, a first high-pass filter that passes a signal of 1309.75 MHz to 1548 MHz, which is a first intermediate frequency band of CS broadcasting, without attenuating it;
1309.75-1 which is the first intermediate frequency band of CS broadcasting
a first amplifier circuit that amplifies a 548 MHz signal;
A high frequency switching circuit that switches between the first intermediate frequency band of S and the first intermediate frequency band of CS broadcasting, and an image frequency component that is the sum of twice the first intermediate frequency and second intermediate frequency of BS and CS broadcasting. 1841.54MHz~2353
．． An image filter for removing 56 MHz and preventing image interference from occurring, and an image filter for attenuating signals below 1035.98 MHz, which is a frequency band lower than the first intermediate frequency band of the BS, and is 10
It is characterized by comprising a second high-pass filter that passes frequencies from 35.98 MHz to 1331.5 MHz, and a second amplification circuit that amplifies the first intermediate frequency band of BS.

0010

[Operation] With the above-described configuration, the present invention can be configured to share an image filter that removes image frequency components of BS and an image filter that removes image frequency components of CS broadcasting. The filter can be simplified.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit diagram of a satellite broadcast receiver according to an embodiment of the present invention. In Figure 1, 1
is an input terminal for the first intermediate frequency signal of the BS. 39 is C
This is an input terminal for the first intermediate frequency signal of S broadcasting. 88 is an output terminal. 3, 4, 6, 7, 9, 19, 24, 25
,29,34,38,41,42,44,45,47,
48, 56, 58, 59, 67, 71, 73, 76, 7
9, 82, 85, 87 are chip capacitors. 2
,5,8,16,17,26,27,40,43,46
,51,55,60,64,74,75,77,78,
80, 81, 83, 84, and 86 are microstrip lines. 11, 12, 13, 15, 21, 18, 2
0, 22, 28, 33, 30, 36, 52, 53, 49
, 50, 61, 62, 57, 65, 68, and 66 are chip resistors. 10 is a power supply terminal 1. 37 is the power supply terminal 2. 14, 23, 54, and 63 are high frequency transistors. 31, 32, 35, 69, 70, 72 are PI
It is an N diode.

Reference numeral 90 denotes a first high-pass filter that attenuates signals lower than the first intermediate frequency band of the BS and passes the first intermediate frequency band of the BS. 91 is a first amplification circuit that amplifies the first intermediate frequency band of the BS. 92 is B
This is a high frequency switching circuit that switches between the first intermediate frequency band of S and the first intermediate frequency band of CS broadcasting. Reference numeral 94 denotes an image filter for removing an image frequency component that is twice the sum of the first intermediate frequency and the second intermediate frequency of BS and CS broadcasts to prevent image interference from occurring. 95
is a second high-pass filter that attenuates a frequency band lower than the first intermediate frequency band of CS broadcasting and passes the first intermediate frequency band of CS broadcasting. 96 is a second amplification circuit that amplifies the first intermediate frequency band of CS broadcasting.

FIG. 2 shows that signals below 1309.75 MHz, which is a frequency band lower than the first intermediate frequency band of CS broadcasting, are attenuated, and signals of 130 MHz, which is the first intermediate frequency band of CS broadcasting, are attenuated.
It shows the frequency characteristics of the second high-pass filter 95 that passes signals of 9.75 to 1548 MHz without attenuating them.

FIG. 3 shows the frequency of an image filter 94 for removing an image frequency component that is twice the sum of the first intermediate frequency and the second intermediate frequency of BS and CS broadcasts to prevent image interference from occurring. It shows the characteristics.

FIG. 4 shows a method for attenuating signals below 1035.98 MHz, which is a frequency band lower than the first intermediate frequency band of the BS.
It shows the frequency characteristics of the first high-pass filter 90 that passes signals of MHz to 1331.5 MHz without attenuating them.

The operation of the satellite broadcasting receiver configured as described above will be explained below.

[0017] The first intermediate frequency signal input terminal 1 of the BS is connected to the 12 GHz band radio wave received by the antenna from the satellite, which is frequency-converted to the 1 GHz band by a down converter, and then transmitted indoors via a coaxial cable. A first intermediate frequency signal is applied. The signal input to the input terminal 1 of the first intermediate frequency signal of the BS broadcast attenuates the signal lower than the first intermediate frequency band of the BS broadcast shown in FIG. 4 by about 30 dB.
The signal is input to a first high-pass filter 90 that passes the first intermediate frequency band of BS broadcasting. The output signal of the first high-pass filter 90 has a first intermediate frequency band of BS broadcasting of about 1
It is amplified by a first amplification circuit 91 that amplifies it by 5 dB, and passes through a high frequency switching circuit 91 that switches between a first intermediate frequency band for BS broadcasting and a first intermediate frequency band for CS broadcasting;
The image frequency component, which is the sum of twice the first intermediate frequency and second intermediate frequency of BS and CS broadcasting shown in Figure 3, is approximately 50
The signal is input to an image filter 94 for attenuating the signal by dB to prevent image interference, and is transmitted to an output terminal 88.

CS first intermediate frequency signal input terminal 39
12 GHz band radio waves from a satellite received by an antenna are frequency-converted to 1 GHz band by a down converter, and the first intermediate frequency signal of the CS guided indoors via a coaxial cable is applied. The input CS signal from the satellite is passed through a second high-pass filter 95 that attenuates the frequency band lower than the first intermediate frequency band of CS broadcasting by about 30 dB and passes the first intermediate frequency band of CS broadcasting shown in FIG. is input. The output signal of the second high-pass filter 218 is C
The second amplification circuit 96 amplifies the first intermediate frequency band of S broadcasting, and the first intermediate frequency band of BS and CS
The first intermediate frequency band of BS and the first intermediate frequency band of CS broadcasting are input signals through a high frequency switching circuit 92 that switches between the first intermediate frequency band of broadcasting and the first intermediate frequency band of BS and CS broadcasting. The signal is input to an image filter 94 for removing image frequency components that are the sum of twice the intermediate frequency to prevent image interference, and is transmitted to an output terminal 88. In this way, the image fixer 94 that removes the image frequency components of CS broadcasting and BS can be configured with one image filter because the first intermediate frequency of BS and the first intermediate frequency of CS broadcasting are adjacent to each other. It is possible to simplify the image filter in the receiver.

[0019]

As described above, according to the present invention, it is possible to simplify the image filter in a satellite broadcast receiver.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a satellite broadcasting receiver according to an embodiment of the present invention.

[Figure 2] Frequency characteristic diagram of the second high-pass filter

[Figure 3
] Frequency characteristic diagram of image filter

[Figure 4] Frequency characteristic diagram of the first high-pass filter

[Figure 5] Block diagram of a conventional satellite broadcasting receiver

[Explanation of symbols]

1 BS first intermediate frequency signal input terminal 39 CS
Input terminal 88 for broadcasting first intermediate frequency signal Output terminals 3, 4, 6, 7, 9, 19, 24, 25, 29, 34,
38, 41, 42, 44, 45, 47, 48, 56, 5
8, 59, 67, 71, 73, 76, 79, 82, 85
,87 Chip capacitor 2, 5, 8, 16, 17, 26, 27, 40, 43, 4
6, 51, 55, 60, 64, 74, 75, 77, 78
, 80, 81, 83, 84, 86 Microstrip line 11, 12, 13, 15, 21, 18, 20, 22, 2
8, 33, 30, 36, 52, 53, 49, 50, 61
,62,57,65,68,66 Chip resistor 10
Power supply terminal 1 37 Power supply terminal 2 14, 23, 54, 63 High frequency transistor 31,
32, 35, 69, 70, 72 PIN diode 90 First high-pass filter 91 First amplifier circuit 92 High-frequency switching circuit 94 Image filter 95 Second high-pass filter 96 Second amplifier circuit

Claims (1)

[Claims] Claim 1: Attenuating signals below 1035.98 MHz, which is a frequency band lower than the first intermediate frequency band of the BS,
1035.98MHz which is the first intermediate frequency band of BS
A first high-pass filter that passes 1331.5MHz and a first intermediate frequency band of 1035.98M of BS.
A first amplification circuit that amplifies signals of Hz to 1331.5 MHz, and attenuates signals of 1309.75 MHz or lower, which is a frequency band lower than the first intermediate frequency band of CS broadcasting, and amplifies the first intermediate frequency band of CS broadcasting. 1309.75～
a second high-pass filter that passes the 1548 MHz signal without attenuation; a second amplification circuit that amplifies the signal of 1309.75 to 1548 MHz, which is the first intermediate frequency band of CS broadcasting; and the first intermediate frequency band of BS. Obi and C
A high frequency switching circuit that switches between the first intermediate frequency band of S broadcasting and the image frequency component 18 that is the sum of twice the first intermediate frequency and second intermediate frequency of BS and CS broadcasting.
A satellite broadcasting receiver comprising: an image filter for removing frequencies from 51.54 MHz to 2353.56 MHz to prevent image interference from occurring.