JPH0338190A - Antenna input level display device - Google Patents

Abstract

PURPOSE:To display a BS antenna input level in response to the S/N of a BS reception signal by extracting noise for a horizontal scanning period of a vertical blanking period of a BS video signal at a noise extraction circuit and displaying a DC voltage in response to the noise onto a display device. CONSTITUTION:A signal for one horizontal scanning period or plural horizontal scanning periods in a vertical blanking period is extracted by an extraction pulse from a channel selection control microcomputer 7 and outputted from an extraction circuit 6. A substantial video signal is not included in the extracted signal but only noise component is included. The noise is amplified by an amplifier circuit 8, detected by a detection circuit 9 to output a DC voltage proportional to the noise. Then the display inversely proportional to the DC voltage is displayed on the display device 10 as the BS antenna input level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a BS antenna input level display that accurately displays the BS antenna input level and facilitates the installation of a parabolic antenna in a satellite broadcasting (hereinafter referred to as rBsJ) receiving device. It is related to the device.

As shown in Figure 3, the antenna power level display device in a conventional BS receiving device detects high frequency B of the 12 GHz band using a parabolic antenna (100) installed outdoors.
Receive the S signal and convert the received output to a converter (101)
Convert to IGIlz band by using BS tuner (1
403MHz with the second frequency converter (103) of 02)
(or 134 MIIz) and amplified by a second intermediate frequency amplification circuit (104) to derive a second intermediate frequency output signal (2nd IF). The AGC voltage output from the second intermediate frequency amplification circuit (104) is outputted to the outside from the terminal (106) through the buffer circuit (105), and is displayed as it is on the display section (107) as the BS antenna input level. It has become.

However, in general, the BS antenna input signal is an extremely weak signal, and due to the occurrence of thermal noise in the converter (101), etc., the BS antenna input signal from the converter (101) to the BS tuner (102) is The signal has a very poor S/N ratio. On the other hand, the second intermediate frequency amplifier (104)
The AGC voltage from is generally generated even when there is no signal. Therefore, even if the antenna (100) is in a poor installation state, the signal indicating the antenna input level is output with little difference from that in a normal reception state. Therefore, when displaying the input level as in the conventional example above, B
The display appears as if the S signal is being received, making it difficult to properly install the parabolic antenna, resulting in a decrease in the efficiency of the installation work.

In order to solve the above-mentioned problems, the present invention provides a noise extraction circuit for extracting noise in one horizontal scanning period or a plurality of horizontal scanning periods of a vertical blanking period of a BS video signal, and a A channel selection control microcomputer that generates a sampling pulse to remove the above noise, and the extracted BS
A circuit that amplifies noise in the video signal, a detection circuit that detects the amplified noise, and a DC output from the detection.
A display device is provided that performs display based on voltage.

Therefore, the BS received signal is guided to the noise extraction circuit,
This circuit extracts noise in one horizontal scanning period or a plurality of horizontal scanning periods in the vertical blanking period of the BS video signal.

After this noise is amplified by an amplifier circuit, it is detected by a detection circuit and is derived as a DC voltage with a level corresponding to the above noise. By displaying this DC voltage on a display device, it is determined according to the S/N of the BS received signal. The BS antenna can display the human input level.

Tsune” L group FIG. 1 is a block diagram of an embodiment of the invention.

In Figure 1, (1) is a BS that is generally installed outdoors.
It is a parabolic antenna for signal reception, and (2) is a converter that converts the BS signal received by the parabolic antenna (1) to a lower frequency, and the output of the converter (2) has a built-in BS tuner (5). Connect to the input terminal (4) of a color television receiver (3). (6) is a noise extraction circuit that extracts noise within the horizontal retrace period within the vertical retrace period from the BS video signal from the BS tuner (5), and the output of the circuit (6) is output from the amplifier circuit (
8) to the detection circuit (9>), and further to the display device (10).
).

(7) is a microcomputer for channel selection control, and this microcomputer derives a sampling pulse for extracting the noise from the sampling circuit (6) based on the horizontal retrace pulse and the vertical retrace pulse, and uses this to extract the noise from the sampling circuit (6). It is configured to lead to the circuit (6).

Therefore, the BS signal received by the parabolic antenna (1) is converted into a first intermediate frequency signal by the converter (2), and the BS signal is
The desired BS channel is selected by entering the BS tuner (5) from the input terminal (4) of the color TV with built-in tuner (3) and demodulated to a BS video signal.The BS video signal is manually input to the sampling circuit (6). and the tuning control microcomputer (
The signal of one horizontal scanning period or a plurality of horizontal scanning periods during the vertical retrace period as shown in FIG. 2(C) is extracted by the sampling pulse shown in FIG. 2(b) from 7), and the sampling circuit Output from (6). The extracted signal does not contain the original video signal, but only noise components. The noise shown in FIG. 2(C) is amplified by an amplifier circuit (8), detected by a detection circuit (9), and a DC voltage proportional to the noise is output. A display device (lO
Displayed at >.

FIG. 2 shows the timing of video signal extraction.

The horizontal blanking pulse and vertical blanking pulse of the video signal during the vertical blanking period shown in FIG. 2(a) are guided to the tuning microcomputer (7), and the tuning microcomputer (7) Based on the above two pulses, 1 within the vertical retrace period of the BS video signal.
Or as shown in FIG. 2 (c) within multiple horizontal retrace periods,
A sampling pulse is derived and guided to a sampling circuit (6). The sampling circuit (6) uses the sampling pulse shown in FIG. 2(b) from the video signal (a) within the vertical retrace period shown in FIG. 2(a) to extract only the noise component shown in FIG. 2(C). Derive the signal.

It is generally known that the S/N of a BS video signal is proportional to the C/N of a BS first intermediate frequency signal. In this embodiment, by performing a display inversely proportional to the noise component of the BS video signal, the B
The S input level can be displayed.

Since the present invention has the above-described configuration, the BS antenna input level can be displayed in proportion to the C/N of the BS first intermediate frequency signal, and the antenna input level can be accurately displayed. This makes it possible to easily install the antenna.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of FIG. 1, and FIG. 3 is a block diagram of a conventional example. 6--sampling circuit, 7--tuning control microcomputer. 8-Amplification circuit, 9...-Detection circuit, 10-Display device. Applicant Sharp Corporation

Claims (1)

[Claims] (1) A noise extraction circuit that extracts noise in one horizontal scanning period or a plurality of horizontal scanning periods in the vertical retrace period of a satellite broadcasting video signal, and a selection circuit that generates a sampling pulse for extracting the noise in the noise extraction circuit. A station control microcomputer, an amplifier circuit that amplifies noise in the extracted satellite broadcast video signal, a detection circuit that detects the noise amplified by the amplifier circuit, and displays based on the DC output voltage of the detection circuit. 1. An antenna input level display device for a satellite broadcast receiving device, comprising: a display device.