JPH0580074U - Satellite receiver - Google Patents

Abstract

(57) [Abstract] [Purpose] A descrambler for a satellite broadcast receiver, which is provided with an output circuit for directly outputting the FM detection output from the FM detection circuit and an output circuit for outputting via the de-emphasis circuit. The output circuit is selected according to the characteristics of the input signal of so that it can be input to the descrambler. [Structure] The received satellite broadcast signal is F by the FM detection circuit 5.
The M-detected and FM-demodulated audio subcarrier signal and video signal are reproduced by the respective signal processing circuits, and the FM detection signal from the FM detection circuit 5 is input to the input side of the switching unit 7,
One of the output sides of the switching device 7 is input to the first terminal of the switching device 8 and the other is input via the de-emphasis circuit 10 to the switching device 8.
Input to the second terminal of the switch 8 and the output of the switch 8 is connected to the output terminal 9, and the characteristics of the signal output from the output terminal 9 are changed by the characteristics of the descrambler connected to the output terminal 9. And 8 are operated to select and output.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a satellite broadcast receiver, and more particularly to a satellite broadcast receiver provided with an FM detection output terminal for connecting a descrambler. In recent years, several private communication satellites have been launched, but the broadcast signals of these communication satellites may be scrambled, and in order to receive the broadcast signal, descramble is performed. You will need a descrambler to do this.

[0002]

[Prior Art]

 In a conventional satellite broadcast receiver, a high frequency amplifier 2 amplifies a satellite broadcast signal (IF signal) input through an input terminal 1 and converted into a first intermediate frequency signal, as shown in FIG. , The channel received by the frequency conversion circuit 3 is selected, converted into the second intermediate frequency signal, amplified by the IF amplifier 4 and input to the FM detection circuit 5, which is input by the FM detection circuit 5. The satellite broadcast signal is FM-detected, and the FM subcarrier signal and the video signal demodulated by FM are input to the respective signal processing circuits to reproduce the audio signal and the video signal, and the FM detection output from the FM detection circuit 5 is amplified. The output terminal 9 outputs the signal via 6, and a descrambler is connected to the output terminal 9 so that the scramble applied to the broadcast signal of the communication satellite is released and the broadcast signal is received. It was However, in order to prevent the SNR of the high frequency of the video signal from decreasing in the satellite broadcast signal, pre-emphasis is applied to the video signal on the transmitting side to emphasize the high frequency component of the video signal. There is.

[0003]

[Problems to be solved by the device]

 Therefore, since the FM detection output from the FM detection circuit 5 is an output to which pre-emphasis is applied, there is a problem that the operation becomes defective depending on the descrambler connected. The present invention is provided with an output circuit which outputs the FM detection output from the FM detection circuit 5 as it is and a circuit which outputs the FM detection output through a de-emphasis circuit, and the output circuit is switched by a descrambler connected. The purpose is to provide a satellite broadcast receiver that can be connected to various descramblers by making it selectable.

[0004]

[Means for Solving the Problems]

 1 is an electric circuit block diagram of a main part of a satellite broadcasting receiver showing an embodiment of the present invention. As shown in FIG. 1, the received satellite broadcasting signal is FM-detected by an FM detection circuit 5, In the satellite broadcasting receiver which reproduces the demodulated audio sub-carrier signal and the video signal in each signal processing circuit and is provided with the output terminal 9 of the FM detection signal from the FM detection circuit 5, the switching means ( In FIG. 1, switching devices 7 and 8) and a de-emphasis circuit 10 are provided, and the FM detection signal from the FM detection circuit 5 is input to the input side of the switching means to switch the switching means. One of the FM detection signals can be directly output from the output terminal 9, and the other can be output from the output terminal 9 via the de-emphasis circuit 10 and is connected to the output terminal 9. According to the characteristics, by switching the switching means, so that it is possible to select the characteristics of the signal output from the output terminal 9.

[0005]

[Action]

 The present invention is provided with the output circuit which outputs the FM detection output from the FM detection circuit 5 as it is and the circuit which outputs the FM detection output through the de-emphasis circuit 10 with the above-mentioned configuration, and therefore, they are connected. It is possible to connect various descramblers to the output terminal 9 and use the descrambler by switching the output circuit and selecting the characteristics of the signal to be output.

[0006]

【Example】

 1 is an electric circuit block diagram of a main part of a satellite broadcasting receiver showing an embodiment of the present invention, in which the same components as those shown in FIG. 2 are designated by the same symbols. Reference numeral 1 denotes an input terminal, which converts the satellite broadcast signal received by the satellite broadcast receiving antenna into a first intermediate frequency signal by a converter, and inputs the first intermediate frequency signal to the high frequency amplifier 2 through the input terminal 1. Has been done. The high frequency amplifier 2 amplifies and outputs the input first intermediate frequency signal and inputs it to the frequency conversion circuit 3. The frequency conversion circuit 3 selects a channel to be received and converts it into a second intermediate frequency signal. And outputs it to the IF amplifier 4. The IF amplifier 4 amplifies and outputs the input signal and inputs it to the FM detection circuit 5. The FM detection circuit 5 FM-detects the input satellite broadcast signal, inputs the FM-demodulated audio subcarrier signal and video signal to each signal processing circuit to reproduce the audio signal and video signal, and performs FM detection. The signal is input to the amplifier 6. The amplifier 6 amplifies and outputs the input FM detection signal and inputs it to the input terminal of the switching device 7, and one of the output terminals of the switching device 7 is directly connected to the first input terminal of the switching device 8. The other output terminal of the switch 7 is input to the de-emphasis circuit 10.

2A and 2B are explanatory diagrams showing frequency characteristics of each part of FIG. 1, where FIG. 2A is a frequency characteristic diagram of the FM detection output, and FIG. 2B is a frequency characteristic diagram of the de-emphasis circuit. (C) is an overall frequency characteristic diagram of the output of the de-emphasis circuit. For satellite broadcast signals, in order to prevent the SN ratio of the high frequency of the video signal from decreasing, the transmitter side performs pre-emphasis on the video signal to raise the level of the high frequency component of the video signal. Therefore, the frequency characteristic of the FM detection output of the FM detection circuit 5 is as shown in FIG. In the de-emphasis circuit 10, for example, a low-pass filter having a frequency characteristic as shown in FIG. 7B is used to lower the level of the high frequency component of the video signal, and output as shown in FIG. Is input to the amplifier 11 so that the original video signal before pre-emphasis is obtained with the total frequency characteristic of.

The amplifier 11 amplifies and outputs the input signal and inputs the amplified signal to the second input terminal of the switcher 8. The output terminal of the switcher 8 is connected to the output terminal 9 of the FM detection signal. Is provided in the outer box of the satellite broadcast receiver, and the FM detection signal can be input to the descrambler provided outside the satellite broadcast receiver through the output terminal 9. Depending on the descrambler, there are specifications such that the characteristics of the input signal are those shown in FIG. 2 (A) or those shown in FIG. 2 (C). Depending on the descrambler connected to the output terminal 9, the switch 7 By operating 8 and 8, the characteristics of the input signal can be selected. In particular, when the switch 7 is selected to output without passing through the de-emphasis circuit 10, if the de-emphasis circuit 10 and the amplifier 11 do not adversely affect the output, the switch 7 is inserted immediately before the output terminal 9. It is also possible to eliminate the switch 8 that is present and connect the output terminal of the switch 7 and the output from the amplifier 11 directly to the output terminal 9, respectively.

[0009]

[Effect of the device]

 As described above, according to the present invention, the FM detection signal directly output from the FM detection circuit and the FM detection signal output via the de-emphasis circuit can be selected and input to the descrambler. It is possible to provide a satellite broadcasting receiver with an increased variety of connectable descramblers.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential electric circuit of a satellite broadcast receiver, showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing frequency characteristics of each part of FIG.
(A) is a frequency characteristic diagram of FM detection output, (B)
Is a frequency characteristic diagram of the de-emphasis circuit,
(C) is an overall frequency characteristic diagram of the output of the de-emphasis circuit.

FIG. 3 is a block diagram of an electric circuit of a main part of a satellite broadcast receiver, showing a conventional example.

[Explanation of symbols]

 1 Input Terminal 2 High Frequency Amplifier 3 Frequency Conversion Circuit 4 IF Amplifier 5 FM Detection Circuit 6 Amplifier 7 Switching Device 8 Switching Device 9 Output Terminal 10 De-Emphasis Circuit 11 Amplifier

Claims (1)

[Scope of utility model registration request] 1. A received satellite broadcast signal is FM-detected and F
In the satellite broadcasting receiver which reproduces the M demodulated audio sub-carrier signal and the video signal in each signal processing circuit and also has the output terminal of the FM detection signal, the switching means and the de-emphasis circuit are provided, By inputting the FM detection signal to the input side of the switching means and switching the switching means, one can directly output the FM detection signal from the output terminal, and the other outputs the output through the de-emphasis circuit. It is possible to output from the terminal, and by switching the switching means according to the characteristics of the descrambler connected to the output terminal, the characteristics of the signal output from the output terminal can be selected. And satellite receiver.