JPH06224793A - Reception level checking circuit - Google Patents

Abstract

PURPOSE:To quantitatively measure and display a reception level. CONSTITUTION:Among signal components outputted from an FM demodulation circuit 8, 8MHz components are equivalent to noise, however, interlocked with the operation of the AGC circuit of an intermediate frequency amplifier circuit 7 and proportional to the C/N of first intermediate frequency signals. The 8MHz components are separated by a band pass filter 11, amplified by an amplifier 12 and made into DC signals by a detection circuit 13. The pertinent DC signals are encoded by remote control and transmitted to a remote control device 17 and displayed on a display part 21 at the remote control device 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reception level check circuit, and more particularly to a reception level check circuit suitable for a device for receiving satellite broadcasting (hereinafter referred to as BS broadcasting) or communication satellite broadcasting (hereinafter referred to as CS broadcasting). .

[0002]

2. Description of the Related Art In the case of satellite broadcasting such as BS satellite and CS broadcasting, the reception level varies greatly depending on the direction of the antenna. Therefore, for example, it is convenient if the reception level can be easily known when installing the antenna.

An example of such a conventional technique is disclosed in Japanese Utility Model Laid-Open No. 1-133882. This conventional technique amplifies the AGC voltage output from the intermediate frequency amplifier circuit of the VTR with a tuner to operate the VCO,
The signal output from the VCO is sent out by the FM transmitter. The transmitted signal is demodulated as an audio signal by the FM receiver of the remote controller, the audio signal is heard by the earphone, and the strength of the reception level can be known based on the level of the frequency of the audio signal.

[0004]

In the above-mentioned prior art,
It is necessary to judge whether the reception level is good or bad depending on the frequency of the audio signal. Generally, there is a problem that it is difficult to precisely adjust the direction of the antenna because the difference in the pitch of the sound is difficult to detect although it varies depending on the individual.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a reception level check circuit capable of accurately measuring whether the reception level is good or bad without feeling. Especially.

[0006]

In order to solve the above-mentioned problems, the present invention comprises means for interlocking with an AGC circuit of an intermediate frequency amplifier circuit to separate a signal component proportional to C / N of the intermediate frequency signal, It is configured to include means for converting to a DC signal and means for displaying the level of the DC signal based on the DC signal.

[0007]

In cooperation with the AGC circuit of the intermediate frequency amplifier circuit, a signal component proportional to C / N of the intermediate frequency signal is separated and amplified to obtain a DC signal. By displaying the level of the DC signal based on the DC signal, the reception level at the antenna can be quantitatively and accurately displayed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the configuration of FIG. 1, the antenna 3 is B
It is connected to the S converter 4 and the BS converter 4
Is connected to the second frequency conversion circuit 6 of the BS receiver 5. The second frequency conversion circuit 6 is an intermediate frequency amplification circuit 7
The intermediate frequency amplifier circuit 7 is connected to the FM demodulator circuit 8. The intermediate frequency amplifier circuit 7 has an AGC circuit built therein and is operated.

The FM demodulation circuit 8 includes a video signal processing circuit 9,
The audio signal demodulation circuit 10 and the band pass filter 11 are connected. The bandpass filter 11 is connected to an amplifier 12, and the amplifier 12 is connected to a detection circuit 13. The detection circuit 13 is connected to a predetermined input terminal of a microcomputer (hereinafter, simply referred to as a microcomputer) 15. A predetermined output terminal of the microcomputer 15 is connected to the LED 16. A C / N detection circuit 14 is configured by the band pass filter 11, the amplifier 12, and the detection circuit 13 described above.

The photodiode 18 provided in the remote controller 17 is connected to a predetermined input terminal of the microcomputer 19. A predetermined output terminal of the microcomputer 19 is connected to the LED drive circuit 20. The LED drive circuit 20 is connected to the display unit 21. This display unit 21
Is an LED that can display the date characters as shown in Fig. 2.
It is said that.

Next, the operation will be described. The 12 GHz band broadcast signal received by the antenna 3 is converted by the BS converter 4 into a 1 GHz band first intermediate frequency signal. The first intermediate frequency signal is input to the second frequency conversion circuit 6 at 402.
It is converted to the second intermediate frequency signal in the 78MHz band. The second intermediate frequency signal is supplied to the FM demodulation circuit 8 via the intermediate frequency amplification circuit 7.

In the FM demodulation circuit 8, the above-mentioned second intermediate frequency signal is subjected to FM demodulation. The signal subjected to the FM demodulation is supplied to the video signal processing circuit 9, the audio signal demodulation circuit 10, the band pass filter 11, etc., respectively. The video signal processing circuit 9 performs processing for demodulating the video signal, and the audio signal demodulation circuit 10 performs processing for demodulating the audio signal.

The band pass filter 11 extracts a frequency component of 8 MHz from the signal subjected to FM demodulation. This frequency component is detected by the detection circuit 13 via the amplifier 12.
Is converted into a DC signal. As described above, the C / N detection circuit 14 uses a frequency component of 8 MHz.
This is because the 8 MHz frequency component output from the FM demodulation circuit 8 corresponds to noise.
In conjunction with the operation of the GC circuit, the C / N of the first intermediate frequency signal
It is proportional to (carrier noise ratio).
The DC signal formed by the detection circuit 13 is supplied to the microcomputer 15.

The microcomputer 15 converts the input DC signal into a predetermined remote control code and supplies the remote control code to the LED 16. The LED 16 transmits an optical signal according to a predetermined remote control code.

In the photodiode 18, the optical signal sent from the LED 16 is photoelectrically converted, and the photoelectrically converted signal is supplied to the microcomputer 19.

The microcomputer 19 decodes the photoelectric conversion signal described above, reproduces a DC signal corresponding to the output of the detection circuit 13, and supplies the DC signal to the LED drive circuit 20. L
In the ED drive circuit 20, the display unit 21 is controlled to display the numerical value corresponding to the above DC signal. On the display unit 21 shown in FIG. 2, the antenna level is displayed as “50”, for example.

In this embodiment, of the signal components output from the FM demodulation circuit 8, the 8 MHz component corresponds to noise, but it operates in conjunction with the operation of the AGC circuit of the intermediate frequency amplifier circuit 7.
It is proportional to the C / N of the intermediate frequency signal. The above 8 MHz component is separated by a bandpass filter 11, amplified by an amplifier 12, and converted into a DC signal by a detection circuit 13. The DC signal is converted into a remote control code and sent to the remote control 17. The remote control 17 decodes the remote control code to restore the DC signal and displays it on the display unit 21 of the remote control 17.

Therefore, the reception level can be detected quantitatively. As a result, precise direction adjustment of the antenna can be easily performed. Also, in this embodiment, BS or CS
Adjustment according to the actual reception state after amplifying the input signal becomes possible, and it is possible to perform adjustment with even higher precision than in the past.

[0019]

According to the present invention, the reception level can be quantitatively detected. Therefore, there is an effect that the precise direction adjustment of the antenna can be easily performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a remote controller.

[Explanation of symbols]

 7 Intermediate frequency amplification circuit 8 FM demodulation circuit 11 Band pass filter 12 Amplifier 13 Detection circuit 14 C / N detection circuit 20 LED drive circuit 21 Display section

Claims (1)

[Claims] 1. A means for separating a signal component which is interlocked with an AGC circuit of an intermediate frequency amplifier circuit and is proportional to C / N of an intermediate frequency signal, a means for converting to a DC signal, and a DC signal based on the DC signal. A reception level check circuit comprising: means for displaying a signal level.