JPS5838036A - Level detecting system - Google Patents

Abstract

PURPOSE:To interrupt an output before characteristics of an output from a control system is deteriorated, by supplying the output to an automatic frequency control circuit or automatic phase control circuit, and a level detection circuit from different rectangular converting circuits from gains. CONSTITUTION:Rectangular converting circuit 1, 5 convert an input sinusoidal wave into a rectangular wave respectively and input the result to an automatic frequency control circuit or automatic phase control circuit 2, and a level detection circuit 3. The circuits 1 and 5 have the same threshold value converting the sinusoidal wave into the rectangular wave and the gain of the circuit 5 is taken lower than that of the circuit 1. Thus, before the characteristics of the output of the circuit 2 are completely deteriorated, the circuit 3 gives an output, controls an output intrruption circuit 4 and interrupts the output from the circuit 2. Thus, the deteriorated output such as increase in noise can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a level detection method that can turn off the output before the output characteristics deteriorate in a control system that detects a drop in input level and turns off the output. .

The carrier device includes an automatic frequency control circuit that divides a certain input signal to generate a signal of a specific frequency, for example, in order to obtain various carrier wave signals and pilot signals.
An automatic phase control circuit is used that controls a constant input signal to a specific phase and outputs the signal.

In these control circuits, the characteristics at the output generally deteriorate gradually as the level of the input signal decreases. For automatic frequency control circuits and automatic phase control circuits,
Output noise increases as input level decreases. For this reason, a circuit is installed to detect the input signal level, and when the input signal level is abnormal, the output is controlled to be cut off. You can gain and gain.

FIG. 1 shows a conventional level detection method in an automatic frequency control system or an automatic phase control system.

1 is a rectangular conversion circuit which converts an input sine wave into a rectangular wave and outputs it. Reference numeral 2 denotes an automatic frequency control circuit or an automatic phase control circuit, which generates a sine wave output whose frequency or phase is automatically controlled from an input rectangular wave. 3 is a level detection circuit which detects the output rectangular wave level of the rectangular conversion circuit 1 and generates an output when the level falls below a certain level. Reference numeral 4 indicates an output cutoff circuit, which normally passes the output sine wave of the automatic frequency control circuit t or the automatic phase control circuit 2, but is cut off when the output of the level detection circuit 3 is generated.

In this way, in an automatic frequency control system or an automatic phase control system, an input sine wave is converted into a rectangular wave, and the automatic frequency control circuit or the automatic frequency control circuit obtains a required output in addition to the automatic phase control circuit. At this time, the level of the rectangular wave output is detected and control is performed to turn off the output when the level is abnormal, but before the level detection circuit 3 generates an output, the output whose characteristics have deteriorated, for example, noise has increased. There is an area where the output is sent.

The present invention aims to eliminate such drawbacks of the prior art, and its purpose is to provide a control system whose output characteristics deteriorate due to a decrease in input level.

In the level detection method of the present invention, a rectangular conversion circuit that supplies output to the automatic frequency control circuit or automatic phase control circuit, and a rectangle conversion circuit that supplies output to the level detection circuit are separately provided, and each rectangular By making the gains of the conversion circuits different, it is possible to turn off the automatic frequency control circuit or the automatic phase control circuit before the output characteristics thereof deteriorate.

Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 2 shows the configuration of an embodiment of the level detection method of the present invention. In this figure, the same parts as in FIG. 1 are designated by the same numbers, and 5 is a rectangular conversion circuit.

In FIG. 2, the configurations of the rectangular conversion circuit 1, automatic frequency control circuit or automatic phase control circuit 2, and output cutoff circuit 4 are the same as in the case of FIG. The rectangular conversion circuit 5 converts the input sine wave into a rectangular wave and supplies it to the level detection circuit 3, and the level detection circuit 5 detects the level of the input rectangular wave and generates an output when the level becomes constant and becomes below the veil. do. The output cutoff circuit 4 is configured by passing or cutting off the output of the automatic frequency control circuit or the automatic phase control circuit 2, depending on the output of the level detection circuit 3. control.

The rectangular conversion circuit 1 and the rectangular conversion circuit 5 have the same threshold value when converting a sine wave into a rectangular wave, but have different gains. Therefore, for example, by setting the gain of the rectangular conversion circuit 5 lower than that of the rectangular conversion circuit 1, the level detection circuit 6 can output the output before the characteristics of the output of the automatic frequency control circuit or the automatic phase control circuit 2 completely deteriorate. is generated, and the output is cut off in the output cutoff circuit 4, so that it is possible to prevent the output °O with deteriorated characteristics from occurring.

FIG. 6 shows the structure of another embodiment of the level detection method of the present invention. In this figure, the same parts as in FIG. 2 are designated by the same numbers, and 6 is an attenuator.

In the case of the fifth flA, the input signal is subjected to a certain attenuation through the attenuator 6 and then input to the rectangular conversion circuit 5, and the output of the rectangular conversion circuit 5 is applied to the level detection circuit 3. In this case as well, by appropriately setting the respective gains of the rectangular conversion circuits 1 and 5 and the amount of attenuation of the attenuator 6, the same effect as in the embodiment shown in FIG. 2 can be obtained.

As explained above, according to the level detection method of the present invention,
By separately providing a rectangular conversion circuit that supplies a rectangular wave to the automatic frequency control circuit or automatic phase control circuit and a rectangular conversion circuit that supplies input to the level detection circuit, and making the gains of the two-legged conversion circuits different, the input This is extremely effective because the output can be cut off before the output characteristics of the automatic frequency control circuit or the automatic phase control circuit deteriorate due to a decrease in mold level.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of a conventional level detection method, and FIGS. 2 and 3 are block diagrams showing the structure of an embodiment of the level detection method of the present invention. 1.5 - rectangular conversion circuit, 2... automatic frequency control circuit or automatic phase control circuit, 6... level detection circuit, 4
...output disconnection, 6...attenuator. Patent applicant Gobe Tamamushi, patent attorney representing Fujitsu Ltd. (3 others)

Claims (1)

[Claims] The input sine wave is converted into a rectangular wave through a rectangular conversion circuit, and then supplied to an automatic frequency control circuit or an automatic phase control circuit to obtain the required output, and a level detection circuit detects the level of the rectangular wave input to keep it below a certain level. The automatic phase control circuit or the control system that turns off the output of the automatic phase control circuit when the voltage decreases to is supplied as an input to the level detection circuit, and the gain of the second rectangular conversion circuit is made to be different from the gain of the rectangular conversion circuit.