JPH05244602A - Satellite broadcasting transmission/reception device - Google Patents

Abstract

PURPOSE:To set the control of a noise removal circuit to be satisfactory with simple circuit constitution by executing control in accordance with the error flag of an error correction circuit so as to return a signal to a correct PCM sound signal. CONSTITUTION:The pulse of the error flag in the error correction circuit of a PCM decoder 2 is supplied to an integrating circuit 16. It obtains a pulse as a DC detection signal corresponding to a duty ratio and supplies it to the variable gain amplifier circuit 1e of the noise removal circuit 1 as a gain control signal. When a C/N value is deteriorated, the duty ratio in the high level of the error flag becomes large, and a DC detection signal becomes large. Since the circuit 1 is controlled in accordance with the error flag of the error correction circuit provided for the PCM decoder 2, the DC detection signal obtained through the circuit 16 is proportional to the C/N value of an input signal. Thus, the circuit 1 is controlled by the C/N value and noise removal quantity increases in accordance with the deterioration of the C/N value. Then, the detection circuit of the detection value of the C/N value becomes unnecessary, and the circuit 1 can satisfactorily be controlled with simple constitution.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, the value of the signal-to-noise ratio (S / N) of the image of a satellite broadcast receiving apparatus that receives satellite broadcast is not the electric field strength of the input radio signal but the value of the received power-to-noise ratio (C / N) Is uniquely determined by C / of this satellite broadcasting receiver
The N value is determined by the transmission power sent from the satellite, weather conditions, converter performance, and antenna diameter.

Conventionally, in a satellite broadcast receiving apparatus, this C
In order to reduce the deterioration of the video S / N value as much as possible even when the / N value deteriorates, the polarity of the noise component obtained from the input video signal through the high-pass filter in the video signal system is inverted. A noise eliminating circuit adapted to be mixed is provided, and when the C / N value is deteriorated, the noise eliminating circuit is operated manually or automatically.

When the noise eliminating circuit is automatically operated, it is necessary to detect the C / N value.
In order to detect the N value, noise outside the band of the satellite broadcast signal is detected, and the noise amount is converted into a C / N value.

[0005]

However, the noise outside the band of the satellite broadcast signal is detected, and the noise amount is calculated as C /
When converting to N value, the circuit configuration is relatively complicated,
There was the inconvenience of becoming relatively expensive.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to make it possible to favorably control a noise elimination circuit with a relatively simple circuit configuration.

[0007]

A satellite broadcast receiving apparatus of the present invention, for example, as shown in FIG. 1, has a PCM decoder 2 for returning a noise removing circuit 1 provided in a video signal system to a correct PCM audio signal.
The control is performed according to the error flag of the error correction circuit provided in. Further, the satellite broadcast receiving apparatus of the present invention has, for example, as shown in FIG. 1, a noise removing circuit 1 provided in a video signal system and a PCM decoder 2 for returning a correct PCM audio signal, and an error correction provided in the PCM decoder 2 is provided. A DC detection signal corresponding to the error flag of the circuit is obtained, and the noise removal amount of the noise removal circuit 1 is controlled by the DC detection signal.

[0008]

According to the present invention, the noise removal circuit 1 is controlled in accordance with the error flag of the error correction circuit provided in the PCM decoder 2. The error flag of the error correction circuit of the PCM decoder 2 is the input signal. Since it is proportional to the C / N value, it is equivalent to controlling the noise removing circuit 1 with this C / N value. This noise removing circuit 1 can be well controlled and also serves as an error flag of the PCM decoder 2. Therefore, the circuit configuration for detecting the C / N value is unnecessary.

Further, according to the present invention, since the noise removal amount of the noise removal circuit 1 is controlled according to the error flag of this error correction circuit, when the C / N value is bad, the noise removal amount is increased (resolution). If the C / N value is good, the noise removal amount is reduced, so that the image S / N can be kept substantially constant.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the satellite broadcast receiving apparatus of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 3 denotes a broadcasting satellite, and the satellite broadcasting signal in the 12 GHz band from the broadcasting satellite 3 is received by the BS antenna 4. The satellite broadcasting signal converted into the 1 GHz band by the BS converter 4a of the BS antenna 4 is transmitted to the B via the BS cable 5.
Supply to the S tuner 6.

The signal from the BS tuner 6 is supplied to a de-emphasis circuit 9 through a buffer amplifier circuit 7 which constitutes a video signal system and a low-pass filter 8 which passes a signal of 4.5 MHz or less, and the de-emphasis circuit 9 is supplied.
Y / C separation circuit 1 that separates the video signal obtained at the output side of the
Supply to 1.

The chroma signal C obtained by the Y / C separating circuit 11 is supplied to the chroma signal output terminal 11C, and the luminance signal Y obtained by the Y / C separating circuit 11 is outputted through the noise eliminating circuit 1 as a luminance signal. It is supplied to the terminal 12.

The noise removing circuit 1 supplies the input luminance signal to the mixing circuit 1a and also supplies the input luminance signal to the high-pass filter 1b to extract a noise component, and the noise component is polarized through the limiter circuit 1c. Is supplied to the polarity inverting circuit 1d for inverting, and the noise component whose polarity has been obtained at the output side of the polarity inverting circuit 1d is supplied to the mixing circuit 1a via the variable gain amplifying circuit 1e, and the mixing circuit 1a is supplied. The output signal of is supplied to the luminance signal output terminal 12. In this mixing circuit 1a, the noise component whose polarity is inverted is added to the input luminance signal, and the noise component of the input luminance signal is canceled. The gain of the variable gain amplifier circuit 1e is controlled by an error flag of an error correction circuit of the PCM decoder 2 which will be described later.

The chroma signal C obtained at the chroma signal output terminal 11C and the luminance signal Y obtained at the luminance signal output terminal 12 are supplied to a video signal processing circuit, as is well known, and a red signal R, a green signal G and a blue signal are supplied. B is obtained and the information is supplied to, for example, a color cathode ray tube.

The signal obtained at the output side of the BS tuner 6 is supplied to a QPSK demodulation circuit 14 via a bandpass filter 13 which passes a 5.73 MHz signal forming an audio signal system. The output signal is supplied to the PCM decoder 2.

As is well known, the PCM decoder 2 is a PCM decoder.
The signal of the code string is descrambled and deinterleaved to the original correct digital signal, which includes an error correction circuit and an interpolation circuit for correcting bit errors.

The error flag of the error correction circuit of the PCM decoder 2 is at the high level "H" in the section where there is a bit error detection signal output and a bit error exceeding the correction capability. In this case, as the C / N value deteriorates, bit errors in the audio data begin to occur, and as the number of bit errors increases, the high level “H” section increases, and the pulse shape is as shown in FIG.
As shown in C, a pulse having a large duty ratio in the high level "H" section is obtained.

FIG. 2A is an error flag when there is no deterioration of the C / N value, and FIG. 2B is an error flag when the deterioration of the C / N value starts to occur, and therefore this PC
The error flag of the error correction circuit of the M decoder 2 is C /
A pulse having a duty ratio according to the N value can be obtained.

The PCM audio signal obtained by the PCM decoder 2 is supplied to the PCM audio signal processing circuit 15, and the P
The CM audio signal processing circuit 15 converts the analog audio signal and supplies it to the speaker.

In this example, the error flag pulse of the error correction circuit of the PCM decoder 2 as shown in FIG. 2 is supplied to the integration circuit 16. The integration circuit 16 obtains a DC detection signal having a DC value corresponding to the duty ratio of the error flag pulse, and the DC detection signal is supplied to the noise removal circuit 1
The variable gain amplifying circuit 1e is supplied as a gain control signal.

In this case, when there is no deterioration of the C / N value, there is no high level "H" section of the error flag as shown in FIG. 2A, so that the DC detection signal on the output side of the integrating circuit 16 is zero. The variable gain amplifier circuit 1e does not operate, there is no noise component supplied to the mixing circuit 1a, there is no canceling amount of this noise, and the noise removing circuit 1 does not operate.

Further, the gain of the variable gain amplifier circuit 1e is determined by the magnitude of the DC detection signal, and when the C / N value is deteriorated, the high level "H" of the error flag is correspondingly increased.
Since the duty ratio of the variable gain amplifier circuit 1e becomes large and the DC detection signal becomes large accordingly, the noise component from the variable gain amplifier circuit 1e becomes large, and the canceling amount of the noise component in the mixing circuit 1a becomes large accordingly. In this case, the amount of high frequency components is reduced according to the amount of cancellation in the luminance signal, so that the resolution is sacrificed. Others are configured similarly to the conventional satellite broadcast receiving device.

Since this example is constructed as described above, a PC
The noise removal circuit 1 is controlled according to the error flag of the error correction circuit provided in the M decoder 2, and the error detection circuit of the error correction circuit of the PCM decoder 2 receives the DC detection signal obtained via the integration circuit 16 as an input. C / N of signal
Since it is proportional to the value, it is equivalent to controlling the noise eliminating circuit 1 with this C / N value, and the noise eliminating circuit 1 can be well controlled and also serves as an error flag of the PCM decoder 2. Therefore, the circuit configuration for detecting the C / N value is unnecessary, the circuit configuration is simpler, and the cost is lower.

According to this example, the PCM decoder 2
The DC detection signal corresponding to the error flag of the error correction circuit is obtained, the noise removal amount of the noise removal circuit 1 is controlled according to the DC detection signal, and the noise removal amount is increased according to the deterioration of the C / N value. Therefore, there is an advantage that the image S / N can be kept substantially constant.

In the above embodiment, the error flag was directly supplied to the integrating circuit 16 to obtain the DC detection signal, but instead of this, the number corresponding to the high level "H" section of the error flag pulse is obtained. It is also possible to obtain a DC pulse and obtain a DC corresponding to the number of pulses to obtain a DC detection signal. Further, the present invention is not limited to the above-described embodiments, and needless to say, various other configurations can be adopted without departing from the gist of the present invention.

[0026]

According to the present invention, since the noise removing circuit 1 is controlled according to the error flag of the error correcting circuit provided in the PCM decoder 2, the noise removing circuit can be well controlled and the error flag can be controlled. Since it is also used, C /
A circuit configuration for detecting the N value is not necessary, the circuit configuration is simpler, and the cost is lower.

Further, according to the present invention, the DC detection signal corresponding to the error flag of the PCM decoder is obtained, and the noise removal amount of the noise removal circuit 1 is increased in accordance with the DC detection signal, so that the video S / N is improved. There are benefits that can be kept approximately constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a satellite broadcast receiving apparatus of the present invention.

FIG. 2 is a diagram for explaining the present invention.

[Description of Reference Signs] 1 noise elimination circuit 1a mixing circuit 1b high-pass filter 1d polarity reversing circuit 1e variable gain amplification circuit 2 PCM decoder

Claims (2)

[Claims] 1. A satellite broadcast receiving apparatus, characterized in that a noise removing circuit provided in a video signal system is controlled according to an error flag of an error correction circuit provided in a PCM decoder for returning a correct PCM audio signal. 2. A noise removing circuit provided in a video signal system and a PCM decoder for returning to a correct PCM audio signal so as to obtain a DC detection signal according to an error flag of an error correction circuit provided in the PCM decoder. According to another aspect of the present invention, there is provided a satellite broadcast receiving apparatus characterized in that the noise removal amount of the noise removal circuit is controlled by the DC detection signal.