JPH0618300Y2 - Noise measuring device - Google Patents

Description

[Detailed Description of the Device] “Industrial Application Field” This device converts the frequency of a noise input with the output of a frequency sweep oscillator, detects the output with a quasi-peak detector circuit, and displays the detected output with a cathode ray tube. The present invention relates to a noise measuring device which supplies a vertical deflection circuit of a cathode ray tube display and a sweep signal for a frequency sweep oscillator to a horizontal deflection circuit of a cathode ray tube display.

"Prior Art" Fig. 3 shows a general configuration of a noise measuring apparatus. Input terminal 1
The noise input input from 1 is frequency-converted by the output of the frequency sweep oscillator 13 in the frequency converter 12, only the predetermined frequency component in the frequency-converted output is amplified by the intermediate frequency amplifier 14, and the amplified output is It is detected by the quasi-peak detection circuit 15, and the detected output is the cathode ray tube display 16
Of the vertical deflection circuit. The oscillation frequency of the frequency sweep oscillator 13 is swept by the sweep signal of the sweep signal generator 17, and the sweep signal is supplied to the horizontal deflection circuit of the cathode ray tube display 16. Sweep signal falling start point (sweep end)
During the period from immediately before the start of the rising edge (start of the sweep) to the cathode ray tube display 1 from the terminal 18 of the sweep signal generator 17, a blanking signal for erasing the display of the cathode ray tube display 16 is displayed.
6 is supplied.

The quasi-peak detection circuit 15 includes an amplifier 19 as shown in FIG.
Is supplied to the diode 21, the output of the diode 21 is charged into the capacitor 24 through the resistor 23 of the time constant circuit 22, and the charge of the capacitor 24 is stored in the resistor 23,
After being discharged through 25, the voltage of the capacitor 24 is supplied to the buffer amplifier 26. The discharge time constant (R1 + R2) C1 is sufficiently larger than the charge time constant R1C1 of the time constant circuit 22 and is 100 times or more.

"Problems to be solved by the invention" Now, as shown in FIG.
It is assumed that the display 29 corresponding to the noise input is obtained on the display surface 28 of No. 6. When the frequency of the frequency sweep oscillator 13 reaches a value corresponding to the noise input in the retrace line section 31 of the sweep 27, the noise input charges the capacitor 24 as shown by the curve 32 and gradually discharges it. If the start of sweeping is fast as shown by the curve 33, the signal during the blanking interval is displayed on the display surface 28 as shown by the display 34,
The data will be incorrect. In order to prevent such an erroneous display 34 from appearing, it was necessary to delay the start of the next sweep sufficiently as shown by the curve 35.

"Means for Solving the Problem" In the present invention, a switch is connected in parallel to the element of the time constant circuit of the quasi-peak detection circuit, and the switch is turned on during the blanking interval of the sweep signal.

[Embodiment] FIG. 1 shows a quasi-peak detection circuit which is an essential part of an embodiment of the present invention, and the portions corresponding to those in FIG. In this embodiment, the capacitor 24 of the time constant circuit 22 is
A switch 36 is connected in parallel with the switch 36. The switch 36 is controlled by a blanking signal from the terminal 18 of the sweep signal generator 17 to turn on the blanking interval.

According to this configuration, the capacitor 24 is provided in the blanking section of the sweep signal.
Is charged, the charge is immediately discharged through the switch 36. Therefore, the start of the next sweep can be accelerated. As shown in FIG. 2, the diode 21 and the resistor 23
Connect switch 37 in parallel with and connect switch 37 to terminal 1.
It may be controlled by a blanking signal from 8 and turned on during blanking. Since the output impedance of the amplifier 19 is small, the charges charged in the capacitor 24 in the blanking interval are discharged through the switch 37 and the amplifier 19 in a short time.

“Effect of device” As described above, according to this device, the electric charge charged in the time constant circuit of the quasi-peak detection circuit is discharged in a short time in the blanking interval of the sweep signal, so that the sweep signal sweep The period from the end to the start of the next sweep can be shortened.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an essential part of an embodiment of the present invention, FIG. 2 is a connection diagram showing another example, FIG. 3 is a block diagram showing a general configuration of a noise measuring device, and FIG. FIG. 5 is a connection diagram showing the quasi-peak detection circuit of FIG. 5, and FIG. 5 is a diagram showing the relationship between the display and the sweep signal.

Claims (1)

[Scope of utility model registration request] 1. A noise input is subjected to frequency conversion by an output of a frequency sweep oscillator, the output thereof is detected by a quasi-peak detection circuit, and the detected output is supplied to a vertical deflection circuit of a cathode ray tube display to perform the frequency sweep. In a noise measuring device that supplies a sweep signal for an oscillator to the horizontal deflection circuit of the cathode ray tube display, a switch is connected in parallel with the element of the time constant circuit of the quasi-peak detection circuit, and the switch is connected to the sweep signal of the sweep signal. A noise measuring device which is turned on during a blanking interval.