JP3378800B2 - Satellite broadcast receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a detection signal (detected video and audio signal) from a satellite broadcast receiving tuner.
The present invention relates to a satellite broadcast receiving apparatus for supplying a scramble decoder with the bit stream and its bit stream.

[0002]

2. Description of the Related Art In some paid satellite broadcasting, a signal is scrambled and sent, and the receiving side descrambles the signal for viewing. An electronic device called a set top box may be used for the scrambling. If this set-top box is connected to a television receiver or VTR having a satellite broadcast receiving function, it is possible to receive or record pay satellite broadcasts. Even if you have only one set-top box, you can receive satellite broadcasts on both television sets and VTRs by switching with a switch.

Such a switch function is called a double decoder. Double-decoders are generally always on, as the detection signal and the bitstream can arrive at any time.

Then, when a command for switching the switch to either the television receiver or the VTR comes from the microcomputer or the like, the switch is switched to the necessary side.

[0005]

However, in such a device, there is a problem that the power consumption during standby is increased because the power is always on. The problem of power consumption during standby has become a big social problem in recent years, and reduction of it is desired. In particular, since the double decoder and the scramble decoder are connected by a cable with a 75 ohm termination, the bias current of the output transistor at the final stage of the double decoder is wasted.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and requires descrambling by applying a detection signal and a bit stream from internal and external satellite broadcast receivers. Double decoder for generating a signal from an output transistor, first and second input terminals to which a detection signal and a bit stream from an external satellite broadcast receiver are applied, and the presence or absence of the bit stream from the second input terminal And a bitstream detection circuit for detecting descramble, and a scramble decoder for descramble-supplied with a signal that needs to be descrambled from the double decoder. When the main power of the first device is turned off, the output transistor Off, characterized in that turning on the output transistors and to detect that the bit stream the bit stream to the second input terminal of the detection circuit as an on arrives.

Further, according to the present invention, the detection signal and the bit stream from the first receiver are applied, and the detection signal and the bit stream from the second receiver are applied.
A double decoder for selecting a detection signal from any one of the receivers and a bitstream and applying it to a scramble decoder, wherein a bitstream detection circuit for detecting the presence or absence of the bitstream from the first receiver is provided,
The output transistor at the final stage of the double decoder is not biased according to the output signal of the bit stream detection circuit.

Further, according to the present invention, the detection signal and the bit stream from the first receiver are applied and the detection signal and the bit stream from the second receiver are applied, and the detection signal and the bit stream are applied from either receiver. Is a double decoder for selecting a detection signal and a bit stream from the first receiver and applying the selected bit stream to a scramble decoder. A bit stream detection circuit for detecting the presence or absence of the bit stream from the first receiver is provided. It is characterized in that the power supply state to the double decoder is switched according to the output signal, and power is supplied only to the bit stream detection circuit in the standby state.

[0009]

1 is a block diagram of a satellite broadcast receiving apparatus according to the present invention.
Will be explained. 1 is the detection signal and the bit stream from the satellite broadcast tuner 2 (first receiver) of the VTR and the detection signal and the bit from the satellite broadcast tuner 3 (second receiver) of the TV receiver. A stream decoder and a double decoder for selecting a detection signal and a bit stream from one of the receivers, and 4 a bit stream detection circuit for detecting the presence or absence of the bit stream from the satellite broadcast tuner 3 of the TV receiver. Reference numeral 5 is a scramble decoder, and 6 is a terminal to which a switch control signal for switching from the microcomputer to the satellite broadcast tuner 2 or the satellite broadcast tuner 3 is applied.

The double decoder 1 receives the detection signal and the bit stream from the satellite broadcast tuner 2 of the VTR and the detection signal and the bit stream from the satellite broadcast tuner 3 of the TV receiver. One of the detection signals and the bit stream is selected according to the switch control signal of. The selection is performed, for example, by the switch 7 inside the double decoder 1. The selected signal is applied to the output transistor 8 at the final stage of the double decoder 1 and is led from its emitter to the terminal 9. The resistors 10 and 11 indicate the impedance of the code connecting the double decoder 1 and the scramble decoder 5.
Since the impedances of the resistors 10 and 11 are small as described above, when the output transistor 8 is in the standby state, it becomes necessary to flow a large bias current.

In this way, the selected detection signal and bit stream are descrambled by the scramble decoder 5. The scrambled detection signal and the video signal and audio signal demodulated from the bit stream are returned to the satellite broadcast tuner 2 of the VTR or the satellite broadcast tuner 3 of the TV receiver, which is the transmission source.

When the satellite broadcast tuner 3 of the TV receiver is receiving the satellite broadcast, the bit stream continuously arrives at the terminal 12. Therefore, if it is detected that the bit stream arrives at the terminal 12,
The switch 7 may be switched so that the scramble decoder 5 selects the signal from the satellite broadcast tuner 3 of the TV receiver. A detection signal is applied to the terminal 13. The bitstream is detected by the bitstream detection circuit 4. Since the high and low signals continuously arrive in the bit stream, the bit stream detection circuit 4 can be configured by an integrating circuit or the like. When the bitstream does not arrive due to the detection output signal of the bitstream detection circuit 4, the power supply of the double decoder 1 is cut off. For example, the current of the current source 14 of the output transistor 8 at the final stage is cut off. As a result, the power consumption of the double decoder 1 is significantly reduced. In this case, switch 7
Is always set to the selected state of the TV satellite broadcast tuner 3, and is turned on when a bit stream arrives from the TV receiver satellite broadcast tuner 3.

FIG. 1 shows a case where the double decoder 1 and the bit stream detection circuit 4 are arranged in a set of home VTRs. Therefore, when the main power supply of the set of household VTRs is off, the double decoder 1 turns on the bitstream detection circuit 4 in the off state, and the double decoder 1 is turned on according to the detection output signal of the bitstream detection circuit. Add power.

[0014]

According to the present invention, a bitstream detection circuit for detecting the presence / absence of a bitstream from the first receiver is provided, and the power supply state to the double decoder is supplied in accordance with the output signal of the bitstream detection circuit. Since it is switched, the power consumption during standby can be reduced. In particular, since the double decoder and the scramble decoder are connected by a cable with a 75 ohm termination, it is possible to reduce the bias current of the output transistor at the final stage of the double decoder, so that a large reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a satellite broadcast receiver of the present invention.

[Explanation of symbols]

1 double decoder 2 VTR satellite tuner 3 Satellite TV tuner of TV receiver 4 bitstream detection circuit 5 scramble decoder 7 switch 8 output transistors

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 5/38-5/63 H04N 7/20 H04B 1/06 H04B 1/16

Claims (3)

(57) [Claims] 1. A double decoder for generating a signal to be descrambled by applying a detection signal from an internal or external satellite broadcasting receiver and a bit stream, and a detection signal from an external satellite broadcasting receiver. And a bitstream are applied to the first and second input terminals, a bitstream detection circuit that detects the presence or absence of the bitstream from the second input terminal, and a signal that needs to be descrambled is supplied from the double decoder. is provided with a scramble decoder for descrambling, the interior of the satellite receiver, a double-decoder and the bit stream detection circuit arranged inside the first device, said the turning off the main power of the first device The output transistor is turned off, the bit stream detection circuit is turned on, and the second input terminal is turned on. A satellite broadcast receiving apparatus, which turns on the output transistor when detecting that the bit stream has arrived at a child. 2. The first device is a video tape recorder, and a detection signal and a bit stream from a television receiver are applied to the first and second input terminals. The satellite broadcast receiver described. 3. The first device is a television receiver, and a detection signal and a bit stream from a video tape recorder are applied to the first and second input terminals. The satellite broadcast receiver described.