SU913271A1 - Method of data extraction from the signal of pickup with frequency output - Google Patents

Description

The invention relates to measuring equipment and can be used in precision measuring systems with a frequency output.

A known method of extracting information from a signal of a frequency sensor, based on alternately connecting to the sensor measuring and reference sensitive elements and counting the number of oscillations from the output of the sensor for a fixed time interval [11.

The disadvantage of this method is the low accuracy of the measurement, since _(the method does not allow to separate the frequency changes caused by the influence of destabilizing factors. ·

A device is known in which for _a variable measuring interval the pulses of the generators with the reference and measuring elements G2] are counted.

The disadvantage of the measurement method with this device is the relatively low accuracy.

The aim of the invention is to improve the accuracy of measurement.

The consistent goal is achieved by the fact that according to the method of extracting information from a sensor signal with a frequency output, based on alternately connecting the measuring and reference sensitive elements to the sensor and counting the number of oscillations from the sensor output for a variable measurement time interval, the operation of changing a variable measurement time interval to those until the number of oscillations from the output of the sensor when connecting a reference sensing element to it becomes equal to the value recorded by sensor calibration.

the basis of the method are the ratio of e 913271 4

Ν »τ (£) ty) ν ₉ τ 0

1 + ά ίηί ^where ^ ibm (*) “compensated measurement interval when a measuring sensor is connected to the sensor;

'Τ (ς) - compensated measurement interval when a reference sensor element is connected to the sensor;

Ν _ίΓ ( _ί ) - the number of oscillations from the output of the sensor at a given point in time during the measurement interval selected during the calibration of the sensor when a reference sensing element is connected to it;

^ βτθ “the ^{number of} oscillations from the output of the sensor at the time of calibration in the case of connecting a reference sensor to it;

ό? ηί - differential of the frequency logotype of the sensor when using this measuring sensitive element

C is the moment of measurement.

T (O

Ίο.

To_

ΣΕΞ ’

Tx (2) (3) where ί _{? Γ} 0 is the frequency value at the calibration point;

Tr measurement interval selected during the sensor calibration;

A ^ m ^ x are the absolute frequency deviations at the calibration point and at a certain x value of the controlled quantity A, caused by the influence of the same destabilizing factor.

It can be shown that ί x * bt _ 'M т t (P where Ν $ ρ (ΐ) is the number of oscillations from the output of the sensor at a given moment in the measurement interval selected 5 M; during the calibration of the sensor, when the reference sensor is connected to it item

Ν _3γ .Ο ~ the number of oscillations from the output of the sensor at the time of calibration if a standard, sensitive element is connected to it.

Using (4), from the expression (2) we obtain m 0 = m (r)

H .o _et after substituting in (3) and X us zameΔί -r-ϊηί gives an expression (1).

_and For the case of a self-generating sensor with an inductive sensor and a frequency output, when the action of destabilizing factors (change in supply voltage and the related change in diffusion and barrier capacitance of the transistor, change in installation capacity with a change in ambient humidity, aging parts, etc. is reduced to equivalent change ^{35 of the} capacitance of the oscillatory circuit, expression (1) can be simplified to

- τω.

The drawing shows a structural diagram of a device that implements the proposed ⁴⁰ proposed method.

The device contains a sensor 1, keys 2 and 3,. Measuring and reference sensitive elements 4 and 5, a key 6, counter 7, indicator 8, you ⁴⁴ numeral device 9, generator 10. The commands generated by the generator 10 provide control. keys 2, 3 and 6, and are also used in. computing device 9 ⁵⁰ for separating information received when connected to a sensor measuring or reference sensitive elements 4 and 5.

Physical controlled measurement.

A value of A is as follows.

First closes the key 2, and from-. measuring sensor 4 (4)

913271 6 is connected to the sensor 1. The duration of the measurement interval is set equal to the value of T _o selected during the calibration of the sensor. the value άΙηίχ recorded in the memory of the computing device 9. Then <0, the key 2 is opened, and the key 3 is closed, which provides a connection to the sensor 1 of the reference sensor element 5. The measurement interval is also set to T ^, Ec-, 5 l Under the influence of destabilizing factors 8, the sensor oscillation frequency changes, then the number Ν ₃ γ (ΐ) registered at the moment of measurement is different from the original 20 value Ν ^ γ.Ο. The number is stored in the computing device 9, and the command for controlling the duration of the pulses of the generator 10 appears at its output. The duration of the measurement interval is adjusted until the equality Ν _3Τ (s) « _βτ .0 is _ensured . The compensating value of the measurement interval duration интер (ΐ) with the reference sensitive element together with other data stored in the computing device 9 are used to calculate the measurement interval ^{with the} measuring ^ · sensitive element by formula (1). Next, the key 3 is opened, the key 2 is closed, providing a measuring sensor element is connected to the sensor, and the pulse duration of the generator-40 of the generator 10 is set equal to the compensating value. The number of oscillations recorded by the counter 7 during the time Τ _{ν% Μ} (ϋ) characterizes the true value of the controlled quantity and read from indicator 8.

This method of extracting information from the signal of the frequency sensor provides improved measurement accuracy due to the correction of the time to count the oscillations from the output of the sensor, taking into account the influence of destabilizing factors on the oscillation frequency.

Claims (1)

Claim A method of extracting information from a sensor signal with a frequency output, based on alternately connecting the measuring and reference sensitive elements to the sensor and counting the number of oscillations from the output of the sensor for a variable measurement time interval, cast in that, in order to improve measurement accuracy, a variable measurement time interval change until the number of oscillations from the output ·; a sensor when a reference sensing element is connected to it, it will not equal the value recorded during sensor calibration.