SU1742735A1 - Method of calibration of digital oscillograph - Google Patents

Abstract

Usage: The invention relates to electrical measuring technique and can be used to calibrate portable digital oscilloscopes. SUMMARY OF THE INVENTION: The method is carried out by inputting a calibrated digital oscilloscope with a reference signal of the meander type and forming an image of this signal on the oscilloscope screen. Using the input amplifier of the calibrated oscilloscope, the variable CALIBRATION resistor sets the conversion factor corresponding to the specified image size of the signal. Then, additionally adjusting the conversion factor, i.e. By stretching or compressing the amplitude scale of a digital oscilloscope and adjusting the zero offset of the conversion path, an image of quantization noise is generated at the upper and lower levels of the image of the reference signal with a uniform distribution with respect to: their levels. In this case, the nominal value of the conversion coefficient is achieved. Obtaining the image of quantization noise at the upper and lower levels of the reference signal indicates that these levels are combined with the corresponding boundaries of the sampling sections. 1 il. WITH S

Description

This invention relates to electrical measuring technology and can be used to calibrate portable and ultra-portable digital oscilloscopes.

The purpose of the invention is to improve the accuracy of calibration,

The drawing shows an image of one period of a reference signal of the type of a meander on a matrix indicator, at the upper and lower limits of which a quantization noise image was obtained.

The method is carried out by submitting a meander-type signal from the device, to the input of a calibrated digital oscilloscope a reference signal of the meander type and forming an image of this signal on the oscilloscope screen. Using the input amplifier of the calibrated oscilloscope, the variable CALIBRATION resistor sets the conversion factor corresponding to the specified image size of the signal. Then, additionally adjusting the conversion factor, i.e. By stretching or compressing the amplitude scale of a digital oscilloscope and adjusting the zero offset of the transformation path (i.e., shifting the entire scale down or up), an image of quantization noise is produced at the upper and lower levels of the reference signal with a uniform distribution relative to these levels. With

ate

This ensures the achievement of the nominal value of the conversion factor.

Obtaining the image of quantization noise at the upper and lower levels of the reference signal indicates that these levels are combined with the corresponding boundaries of the discrete sections. Due to the quanta noise & due to the noise of the input circuits of the digital oscilloscope, the boundary boundaries of neighboring discretes have a finite width equal to the range of the quantization noise.

In the first approximation, the proposed method allows calibrating a digital oscilloscope so many times more accurate than the known, as the noise value of the input circuits of the digital oscilloscope is less than the low-order bit Ug of the digital oscilloscope.

The calibration error according to the proposed method can be further reduced if the combination of the levels of the reference signal with the corresponding boundaries of adjacent intervals (discretions) is carried out in such a way that the probability of obtaining image elements on both sides of each of these limits is approximately 0.5. In this case

the elements of the levels of the reference signal are divided between adjacent lines approximately equally, as shown in the drawing.

The noise distribution obeys the Gaussian law, therefore, the center of the distribution curve coincides with the boundary between the intervals (discretes). The even distribution of noise around one of the levels of the reference signal indicates that this level practically coincides with the boundary between the intervals. This provides high calibration accuracy according to the proposed method.

Claims (1)

Claims A method of calibrating a digital oscilloscope, which includes applying a reference rectangular signal to its input, changing a conversion factor and a zero level offset before receiving a predetermined signal amplitude on the screen, which is characterized by the fact that, in order to improve accuracy, the conversion factor and offset the zero level is produced before the image of the quantization noise is obtained at the upper and lower limits of the image of the reference signal.