JPS62131680A - Pulse signal generator - Google Patents

Abstract

PURPOSE:To generate a stable pulse signal by so designing the titled generator that a pulse signal is generated from a pulse signal generating means when an output of a capacitance coupling means inputted to a differential means exceeds the threshold level of a threshold level setting means inputted similarly to the differential means. CONSTITUTION:When a voice intermediate-frequency signal is inputted to an AM detection means 1, the sine square pulse component being the result of frequency modulation of a sound signal is detected, its output is sent to the capacitance coupling means 2, where the output is superimposed on a reference bias V11. The threshold level V13 is inputted to the differential means 5 together with the sine square pulse component superimposed on the reference bias V11. A pulse signal corresponding to the sine square pulse is obtained by designing the circuitry that a pulse signal generating means 6 is driven by an output of the differential means 5 obtained when the output of the capacitance coupling means 2 inputted thereto exceeds the threshold level of the threshold level setting means 4.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is based on a method in which an input audio signal is frequency modulated (FM).
This invention relates to a pulse signal generator that generates a pulse signal synchronized with a sine-squared pulse of an audio intermediate frequency signal in which the sine-squared pulse is amplitude-modulated (A, M).

[Conventional technology]

In the case of pay programs on cable TV, etc., it is necessary to prevent them from being received on regular TV. As one method, the synchronization signal may be compressed. In order to restore this synchronization signal to its original state, it is necessary to generate pulses stably.

Figure 3 shows the sine squared pulse of FM audio number 48.
FIG. 4(a) is a waveform diagram showing an audio intermediate frequency signal subjected to M. When this audio intermediate frequency signal is subjected to AM detection, it becomes as shown in FIG. 4(a). In Figure 4 (1L), ■.

is the level when the audio intermediate frequency signal level is 0, v2 is the level of only FM, 3 is the peak value of the sine square pulse, and v4 is the threshold for pulse signal generation. Conventionally, the pulse signal shown in FIG. 4(b) was generated by dividing the peak 3 with respect to GND so that 4=+.

[Problem that the invention seeks to solve]

In the conventional pulse No. 48 generation method as described above, when the level (■) fluctuates or the audio signal level, that is, the peak level (■) becomes small, the pulse signal generation method as shown in FIG. There was a problem in that the threshold level (4) of the signal deviates from Q, the pulse width changes, and sometimes the pulse signal is not generated.

This invention was made to solve these problems, and aims to provide a pulse signal generator that can generate stable pulse signals even when the reference bias fluctuates or the audio signal level decreases. purpose.

[Means for solving problems]

The pulse signal generator according to the present invention includes an AM detection means for detecting a sine square pulse of an audio intermediate frequency signal in which an audio signal is FM and a sine square pulse is AM, and the output of the AM detection means is used as a reference bias. A superimposed capacitive coupling means, a peak level detecting means for detecting the peak level of the output of the capacitive coupling means, and a threshold level for generating a tepulus wave signal by dividing the peak level obtained by the peak level detecting means and a reference bias by resistance. a threshold level setting means for setting a threshold level, a differential means to which the output of the capacitive coupling means and the threshold level of the threshold level setting hand R are input; and a pulse signal for generating a pulse (No. It is equipped with a generating means.

[Effect]

In this invention, a pulse signal is generated from the pulse signal generating means when the output of the capacitive coupling means input to the differential means exceeds the threshold level of the threshold level setting means also input to the differential means.

〔Example〕

FIG. 1 is a schematic diagram showing an embodiment of the pulse signal generator of the present invention, in which 1 is an AM detection means, 2 is a capacitive coupling means, 3 is a peak level detection means, 4 is a threshold level setting means, and 5 is a difference 6 is a pulse signal generating means, RI;
R2 is a resistor whose resistance value is rl+r2.

Next, the operation will be explained.

First, when the audio intermediate frequency signal shown in FIG. 3 is input to the AM detection means 1, the frequency-modulated sine square pulse component of the audio signal is detected, and the output thereof is sent to the capacitive coupling means 2. Reference bias v1. superimposed on Next, the output of the capacitive coupling means 2 is detected by the peak level detection means 3.
The peak level ■1□ is detected. The reference bias v, 1 and the peak level ■1□ are input to the threshold level setting means 4, and the threshold level shown in FIG. (1) 13 is obtained as the output. And this threshold level■1. is input to the differential means 5 together with the sine square pulse component superimposed on the reference bias Vtt. 5) Therefore, when the input output of the capacitive coupling means 2 exceeds the threshold level of the threshold level setting means 4, the By driving the pulse signal generating means 6 by the output of the differential means 5, a pulse signal corresponding to a sine square pulse can be obtained.

Note that the width of the pulse signal can be arbitrarily set by changing the resistance value rl+'2 of the resistors R, , R2 and changing the threshold level V+S.

〔Effect of the invention〕

As explained above, the present invention includes an AM detection means for detecting a sine square pulse of an audio intermediate frequency signal in which an audio signal is frequency modulated and a sine square pulse is amplitude modulated; a capacitive coupling means superimposed on the output of the second capacitive coupling means, a peak level detecting means detecting the peak level of the output of the capacitive coupling means B, and a resistor dividing the peak level obtained by the peak level detecting means and the reference bias to generate a pulse signal. A threshold level setting means for setting a threshold level, a differential means to which the output of the capacitive coupling means and a threshold level of the threshold level setting means are input, and a pulse signal in response to the output of the differential means. The pulse signal generating means generates a pulse signal when the output of the capacitive coupling means exceeds the output of the threshold level setting means which is also input to the differential means. Even when a signal is generated and the first bias and the level of the audio signal fluctuate, a stable pulse signal can be generated.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the pulse signal generator of the present invention, Fig. 2 is a diagram showing signal levels in the invention, Fig. 3 is a waveform diagram showing an audio intermediate frequency signal, and Fig. 4 ( a
), (11), (C) is a diagram for explaining a conventional pulse signal generation method. In the figure, 1 is AM
Detection means, 2 is a capacitive coupling means, 3 is a peak level detector 1'9.4 is a switch/download level setting means, 5 is a differential means, and 6 is a pulse signal generating means. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (2 others) Figure 1 Figure 2 Figure 3 Figure 4 (a) Procedural amendment (voluntary) Showa month/day 1, case description Patent application Sho BO-272182 No. 2,
Title of the invention Pulse signal generator 3, relationship to the amended case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4, Attorney Address 5, Mitsubishi Electric Corporation, 2-2-3 Marunouchi, Chiyoda-ku, Tokyo, Detailed explanation of the invention and drawing 6 in the specification subject to amendment, Contents of amendment (1) Specification, page 2, 11 - In line 12, ``to return to the original state, use a pulse'' is corrected to ``to return to the original state, use a synchronized pulse.'' (2) Similarly, "peak value" on page 2, line 19, is corrected to "peak level." (3) Similarly, in the second line of the third page, [beak ■3 is divided with respect to GND] is corrected to "fix the threshold level v4 with respect to the peak level v3 and GND and use it as a division ratio." (4) Similarly, in page 5, line 20, "it will be input" is corrected to "it will be input." (5) Similarly, "threshold level" in lines 2 and 3 of page 6 is corrected to "threshold level v13". (6) Correct Figure 1 as shown in the attached sheet. that's all

Claims (1)

[Claims] AM detection means for detecting the sine square pulse of the audio intermediate frequency signal in which the audio signal is frequency modulated and the sine square pulse is amplitude modulated; and capacitive coupling means for superimposing the output of the AM detection means on a reference bias. A peak level detection means for detecting the peak level of the output of the capacitive coupling means, and a threshold level setting for setting a threshold level for pulse signal generation by resistively dividing the peak level obtained by the peak level detection means and the reference bias. means, differential means to which the output of the capacitive coupling means and the threshold level of the threshold level setting means are input, and pulse signal generating means for generating a pulse signal in response to the output of the differential means. A pulse signal generator featuring: