JP2564566Y2 - Carrier frequency monitoring device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier frequency monitoring device, and more particularly to a carrier frequency monitoring device for a television modulated wave.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional carrier frequency monitoring device inputs a television modulated wave from an input terminal 71, and an amplitude limiter 7 for limiting the amplitude of the modulated wave. It has a frequency counter 8 for measuring the carrier frequency of the modulated wave. Next, a conventional operation will be described. The frequency counter 8 has a function of measuring the carrier wave and outputting an abnormal signal from the abnormal signal output terminal 81 to the outside when the measured data deviates from a preset value. I was monitoring the frequency.

[0003]

In the conventional carrier frequency monitoring device, the measurement accuracy is affected by the accuracy of the frequency counter. Therefore, in the case of a carrier that requires precise frequency accuracy, the accuracy of the reference oscillator of the frequency counter is reduced. However, there is a disadvantage that large-scale high-precision equipment is required.

[0004]

According to the present invention, a carrier frequency monitoring apparatus receives a television composite video signal and extracts a chrominance subcarrier frequency synchronized with a color burst. A first frequency synthesizer for converting the reference frequency into a reference frequency, an amplitude limiter for inputting a television modulated wave and limiting the amplitude, a second frequency synthesizer for converting an output signal of the amplitude limiter to a comparison frequency, A gate circuit is provided for comparing a frequency with the comparison frequency and detecting a frequency deviation between the two, and an output unit for outputting an abnormal signal to the outside if the detected frequency difference is abnormal.

[0005]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of a carrier frequency monitoring apparatus according to an embodiment of the present invention.

Next, the configuration and operation of this embodiment will be described. The signal generator 1 extracts a reference signal from a television composite video signal and outputs the signal at a constant level. The frequency synthesizer 2 divides and combines the reference signal to convert the signal into a reference frequency. The amplitude limiter 3 limits the amplitude of the television modulated wave to be monitored and outputs it at a constant level. The frequency synthesizer 4 divides and combines the signal from the amplitude limiter 3 and converts the signal into a comparison frequency corresponding to a reference frequency extracted from a composite video signal of a certain level. The gate circuit 5 detects a deviation between the reference frequency and the comparison frequency and outputs a detection signal. The output unit 6 receives the detection signal and outputs an abnormal signal to the outside if abnormal.

[0007]

As described above, the present invention detects a reference signal from a television composite video signal,
Since it is used as a reference frequency, the reference frequency has the same accuracy as the chrominance signal subcarrier or the synchronization signal. Can be performed with high accuracy.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a conventional carrier frequency monitoring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal generator 2, 4 Frequency synthesizer 3 Amplitude limiter 5 Gate circuit 6 Output part 11, 31 Input terminal 61, 81 Abnormal signal output terminal 7 Amplitude limiter 8 Frequency counter

Claims (3)

(57) [Scope of request for utility model registration] 1. A signal generator for receiving a television composite video signal and extracting a color signal subcarrier frequency synchronized with a color burst, and a first frequency synthesizer for converting the color signal subcarrier frequency into a reference frequency. An amplitude limiter that inputs a television modulated wave and limits the amplitude, a second frequency synthesizer that converts an output signal of the amplitude limiter into a comparison frequency, and compares the reference frequency and the comparison frequency. A carrier frequency monitoring device, comprising: a gate circuit for detecting a frequency deviation; and an output unit for outputting an abnormal signal to the outside if the detected frequency difference is abnormal. 2. A carrier frequency monitoring apparatus according to claim 1, wherein said signal generator is a signal generator for receiving a television composite video signal and extracting a frequency synchronized with a vertical synchronizing signal instead of said color signal subcarrier. . 3. The carrier frequency monitoring device according to claim 1, wherein the signal generator is a signal generator that receives a television composite video signal and generates a frequency synchronized with a horizontal synchronization signal instead of the chrominance signal subcarrier. .