JPH0353672A - Signal discriminator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a method for suppressing malfunctions caused by noise contained in a synchronizing signal that is input synchronously.
The present invention relates to a signal discriminator that uses the periodicity of a synchronization signal to distinguish between a signal and noise and detects only a synchronization signal.

(Prior Art) Figure 4 shows a conventional signal discrimination circuit. iJ4
In the figure, 1 is a synchronization signal input terminal, 7 and 8 are detection outputs with mutually different polarities, 9 and 10 are emitter-coupled transistors, 11 is a current source, and l3 is a DC bias.
The comparison voltage vl for the synchronization input is biased.

In the circuit configured as described above, the synchronization signal inputted from the synchronization signal input terminal 1 is detected using the voltage V1 of the DC bias 13 as a threshold value.

(Problem to be Solved by the Invention) However, in the conventional configuration described above, noise included in the synchronization signal is also detected, so there is a problem in that malfunctions occur due to this noise. It solves such conventional problems,
It is an object of the present invention to provide a signal discriminator that suppresses malfunctions caused by noise contained in synchronization signals.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a sawtooth wave signal to discriminate between signals by changing the detection levels of a synchronization signal and noise. ．． (Function) Therefore, according to the present invention, a detection output is obtained for a periodically input synchronization signal, and non-periodic noise is not detected. (Embodiment) FIG. 1 shows the block structure of a signal discriminator in an embodiment of the present invention. In FIG. 1, 1 is a synchronizing signal input terminal, 2 is a voltage comparator, 3 is a discrimination output, 4 is a sawtooth wave signal, 5 is a trigger signal, and 6 is a sawtooth signal generator. Next, the operation of the above embodiment will be explained. A synchronizing signal inputted from a synchronizing signal input terminal 1 is subjected to a voltage comparison with a sawtooth wave signal 4 obtained from a sawtooth wave signal generator 6 by a voltage comparator 2, and a determined discrimination output 3 is output. Trigger signal 5 is for synchronizing the sawtooth wave signal with the sync signal input. FIG. 2 shows a specific circuit of a voltage comparator of a signal discriminator in an embodiment of the present invention. In FIG. 2, 1, 7, 8, 9, 10, and 11 are the same as in the conventional example shown in FIG. 12 is a sawtooth wave signal. Next, the operation shown in Figure 2 will be explained. The synchronization signal input from the synchronization signal input terminal 1 is compared in voltage with the sawtooth wave signal 12. At this time, the sawtooth wave signal 12 is synchronized with the synchronization signal. Figure 3 shows the characteristics of the voltage comparator, and Figure 3 (
a) shows the relationship between the synchronization signal input and the bias (Vl) due to the sawtooth wave signal in the embodiment of the present invention, and FIG.
b) shows the discrimination output of the voltage comparator of the example. Further, FIG. 3(c) shows the relationship between the synchronizing signal input and the DC bias (Vl) in the conventional example, and FIG. 3(d) shows the discrimination output in the conventional example. As is clear from Fig. 3, in the conventional example, noise is also output as a discrimination output, but in this embodiment, noise is not output as a discrimination output. (
Effects of the Invention) As is clear from the above embodiments, the detection level of the voltage comparator changes depending on the sawtooth wave signal synchronized with the synchronization signal, so the present invention is capable of signal discrimination in which the synchronization signal is detected but noise is not detected. will be held. Therefore, it has the effect of suppressing malfunctions caused by noise.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram of a signal discriminator according to an embodiment of the present invention, Fig. 2 is a circuit diagram of a voltage comparator according to an embodiment of the present invention, and Fig. 3 is a synchronization signal input and discriminator of the voltage comparator. A characteristic diagram showing the relationship between outputs, Figure 4 is a circuit diagram of a conventional voltage comparator.

Claims (1)

[Claims] A voltage comparator which has one input as a periodic signal that is periodically inputted and has another input as a sawtooth wave signal that increases or decreases the voltage with a period equal to or longer than the period of the synchronization signal; It is comprised of a sawtooth wave signal generator that generates the sawtooth wave signal in synchronization with the synchronization detection output obtained from the comparator, and is capable of suppressing malfunctions due to noise contained in the synchronization signal and obtaining a stable synchronization detection output. Characteristic signal discriminator.