SU1026298A2 - Device for automatic measuring of metrological characteristics of digital instruments - Google Patents

Description

I:, I The invention relates to automation and measurement technology and is intended to automatically determine the dynamic characteristics of analog-to-digital converters (ADCs). According to the main author. St. No. a device for automatically measuring the metrological characteristics of digital measuring instruments, comprising a time interval meter, a digital-to-analog converter, the first output of which is connected to the first input of the control unit and static data processing, the second input of which is connected to the first output of the digital ADC and the second output of the digital-analog converter connected to the first input of the comparing unit, the output of which is connected to the first input of the trigger, the output of the comparing unit connecting It is connected to the second input of the turned ADC, the second output of which is connected to the second input of the trigger, the output of which is connected to the input of the time interval meter, the output of which is connected to the third input of the control unit and the static data processing, the second output of which is connected to the input of the digital-analogue converter, The input input driver is connected to the first output of the control unit and static data processing, and the output to the first input of the ADC being calibrated and to the second input of the comparing unit. The device allows automatic measurement of static error characteristics and cycle time for encoding an ADC in dynamic mode 1. The disadvantages of this device are limited functionality. This is due to the fact that the device does not allow to measure an important dynamic characteristic of Alf — the delay time of the sample to be normalized. The purpose of the invention is to expand the functionality of the device. The goal is achieved by the fact that a key and a differentiation unit are inserted into the device for automatic measurement of the metrological characteristics of digital measuring devices, the output of the input signal generator connected to the input of the differentiation unit, the output of which is connected to the first input key. . the comparison block and the output to the fourth input of the control block. The introduction of a differential unit and a key, one input of which is connected to the output of the comparator, allows to measure the value of the derivative of the test signal at the time of launching the ADC. As a result, the error of conversion of the ADC and the value of the derivative of the test signal dating back to the same time point are known (time of the start of the ADC), which allows to calculate the delay time of the reference. In accordance with the methodological guidelines for rationing and determining the dynamic characteristics of an ADC (RDBO-Yb-UE), the delay time is normalized by its systematic component of the aperture time tq, which characterizes the scatter t. The current value of toQ is determined from the ratio t - (-i | ( d). xo (t.) where A (t) is the error of the AlJin transformation at the time; x (t,) is the value of the derivative of the test signal at the same time. Thus, measure the error of the ADC conversion A (t |) and the value of the derivative of the test signal x (t-), determining the current values of ta by formula (1), and then statistically processing them, you can determine the systematic delay tjLC and the aperture time about. The proposed device allows you to measure the current values of the delay of reference t, LQ, determine its probability Tochnical characteristics to and, as well as probabilistic characteristics of the error and cycle time of the ADC coding for any dynamic signals The drawing shows a block diagram of the proposed device. The device contains a digital-to-analog converter (D / A) 1, consisting of a digital setpoint unit 2, the output of which is connected to the input of the converter 3 code - voltage and the first input of the control and static data processing unit 4. The output of the converter 3 is connected to the first

the input of the comparing unit 5, the second input of which is connected to the output of the imager 6 of the input signal and to the first input of the ADC under study 7. The output of the trigger 8 is connected to the input of the meter 9 time intervals, the differentiation unit 10 is connected to the output of the imager 6 of the input signal, and the output - to the first input of the key 11. The output of the comparing unit 5 is connected to the first input of the trigger 8 and to the second inputs of the ADC 7 and the key 11. The first output of the control unit k is connected to the input of the input signal generator 6, the second output is connected to the input home block 2 digital setpoint. The first input of the investigated ADC 7 is connected to the second input of the k block, and the second output of the ADC 7 is connected to the second input of the trigger 8. The output of the meter 9 is connected to the third input of the k block, the fourth input of which is connected to the output of the key 11,

The device works as follows.

According to the work program, the control and processing unit k sets the code of the studied point of the range which is generated by digital setpoint unit 2. An exemplary code is fed to input converter 3, a voltage code, at the output of which a reference signal is formed that corresponds to the code of the point under study. By. to the command from block t, the shaper 6 of the input signal generates a dynamic test signal, which can be deterministic, random, or any other signal of the required kind. The test signal is fed to the input of the ADC under study 7 and simultaneously is fed to one input of the comparing unit 5 to another input of which a signal from the DAC 1 arrives. At the moment of equality of the compared signals t, the comparing unit 5 starts the ADC, switches the trigger 8 to the state 1 and opens the key 11 . The derivative value of the test signal x (t) from the differentiation unit 10 at time t through the public key 11 is supplied to the control and processing unit. After a time equal to the transformation time of the LCP, a code appears at its output, which enters block k. At the same time, another conversion signal appears at the other output of the A / D converter. that switches

The trigger 8 is in the O state. In the block Ч, the model code is subtracted from the result of the conversion. The resulting difference (tj) is

is the value of the error ADC at time. By the formula (1) in the block, the current value of the delay delay to is determined. . Trigger 8 produces impulse | .1, duration

which is equal to the cycle time coding ADC t. These pulses go to the meter 9 time intervals and the measurement results go to the control and processing unit k.

Thus, as a result of each conversion ADC. the current values of the error fi () of the delay time t − j, o and the coding cycle time t are determined. Measurements in one

the scale point is held a set number of times necessary for the manifestation of static patterns.

After holding. series of transformations in one point of the range

The control and processing unit L calculates the probability characteristics of the error and the coding cycle time for this point and sets the code of the next studied Scale Point. Upon completion of measurements at all points of interest in the ADC scale, in block k, the probability characteristics of the CR delay are determined, the systematic delay t.,

and aperture time tq.

Thus, the device allows to measure the probability characteristics of an ADC error in a dynamic mode, the reference delay t,

and its likelihood characteristics and tq, as well as the cycle time for encoding the ADC. In this case, the dynamic test signal can be anything. In addition, if the ADC under study

If the test signal is not sent from the driver 6 of the input signal, but directly from the source of the measured signal, then the indicated dynamic characteristics Aifl. will be determined for real convertible signals.

In the proposed device, in comparison with the known functionality, it becomes possible to determine not only the error and coding cycle time of the A / D converter, but also another standardized characteristic of the A / D converter — the delay time of the readout and its probability xapaKte5 10262986

risks are a systematic shift taking into account the properties of the measured

and aperture time t. In this case, the signals. Known devices, the device detects and to for a separate counting delay and aperture.

The dynamic dynamic test signals are time-only for sinusoidal inputs, including real ones from 5 signals, which limits them. measures the hedgehog signals. This allows for functional capabilities and does not provide the most reliable dynamical characteristics to investigate the dynamic characteristics of the ADC, the maximum of the ADC for different types of signals.

Claims (1)

DEVICE FOR AUTOMATIC MEASUREMENT OF METROLOGICAL CHARACTERISTICS OF DIGITAL MEASURING INSTRUMENTS according to ed. St. Ν '824428, which means that ”in order to expand the functionality of the device, a key and a differentiation unit are introduced into it, and the output of the input signal shaper is connected to the input of the differentiation unit, the output of which is connected to the first input of the key, the second input of which is connected to the output of the comparison unit, and the output to the fourth input of the control unit. 1 1026298 2