SU1388815A1 - Low-frequency output pickup signal meter - Google Patents

Abstract

The invention can be used to measure various electrical and non-electrical quantities. The purpose of the invention is to expand the functionality of the device. The meter contains a generator (G) 2 standard pulses, a driver (F) 3 pulses, keys (c) 4 and 5, an element OR 6 and controlled G 16. The device is entered into K 7, 12 and 15, ne

Description

Rescale I circuit with adjustable scaling factor, trigger 9, low pass 1P filter, F 11 control signal, analog adder 13, F 14 correction signal, information display circuit 17 and synchronizer 18. The measurement precision can be controlled by Г 2 reference pulses. To do this, in a corrective way: - the operation cycle of the device K 5 and 12 is opened, and K 4 and 15 are closed. In this case, the closed loop automatic control. Includes

G 2 reference pulses. If the frequency of the pulses of the controlled G 16 is disconnected from the calibration value, F 14 of the correction signal generates and stores the voltage V, which, acting on the control G 16, returns its frequency to the calibration value. The measuring cycle of the device operation takes place with the participation of a correction voltage, acting on the controlled HG. 16. As a result, the frequency of the controlled G 16 is controlled by the total voltage. 2 Il.

one

The invention relates more to measurement technology and can be used to measure various electrical and non-electrical quantities converted by the sensor into low frequency electrical signals.

The aim of the invention is to improve the accuracy of frequency measurement and the expansion of functionality,

FIG. 1 shows a functional diagram of the proposed device ;; in fig. 2 - time diagrams that show his work.

The device contains an Information Board 1, a generator 2 reference pulses, a shaper 3 pulses, the first and second keys 4 and 5, the element OR 6, the third key 7, the counting circuit 8 with an adjustable conversion factor, trigger 9, the low-pass filter 10, the driver 11 of the control signal, the fourth key 12, the analog adder 13, the correction signal generator 14, the fifth key 15, the controlled oscillator 16, the information display circuit 17, the synchronizer 18.

The information bus 1 is connected to the input of the imaging unit 3 pulses. Reference generator 2: signals are connected to the input of the first key 4, the output of which is connected to the first input of the element OR 6, the second input of which is connected to the output of the second key 5, the input of which is connected to the output of the driver 3. Output

five

about

2 "

35

thirty

the controlled generator of 16 pulses is connected to the input of the third key 7, the control input of which is connected to the output of the element OR 6, and the output to the input of the scaling circuit 8 with an adjustable conversion factor. The trigger setup input 9 is connected to the output of a scaling circuit 8 with an adjustable conversion factor, and the reset input is connected to the output of the OR element 6. The trigger output 9 is connected to the low-pass filter 10 input, the output of which is connected to the control signal generator 11. The input of the fourth key 12 is connected to the output of the control signal generator 11, and the output is connected to the first input of the analog adder 13. The control input of the controlled generator 16 is connected to the output of the analog adder 13. The input of the fifth key 15 is connected to the output of the low-pass filter 10, and the output is connected to the input of the correction signal generator 14, the output of which is connected to the second input of the analog adder 13. The output of the controlled generator 16 is connected to the input of the information display circuit 17. The first output of the synchronizer 18 is connected to the control inputs of the first and fifth keys 4 and 15, the second output of the synchronizer 18 is connected to the control input of the second and fourth keys 5 and 12.

The device works as follows.

Let the oscillation frequency f, at the low-frequency output sensor, be associated with a controlled physical quantity X according to

one

f ah.

(one)

where a is the coefficient of proportionality.

Because f is a low frequency, measuring it in the usual way by counting the number of periods for a selected measurement interval is impractical, since the measuring interval must be very large in order to obtain satisfactory accuracy.

If, however, the measurement of the frequency f is performed by counting the number of pulses of the auxiliary frequency generator during the measurement interval, the equal period of the unknown frequency T, then this number N will be equal to

t

 X

 Tg

AT

one

one

fxT,

where Tg is the period of the following auxiliary frequency pulses. The obtained number N non-linearly depends on the measured physical quantity X and cannot be used for direct digital display.

To eliminate this drawback, we fix the number N N at some chosen level, and make the auxiliary frequency fg variable and change it so that for any unknown period T the condition

N cons-t. (3)

For a variable period T, we introduce the notation Tsch. (the period of the following pulses of the tunable generator), and for a variable auxiliary frequency -.

From the relation (3), taking into account the new designations, it follows

t - i

-n.r

(4) 55

or

„., -I- Nf ,, (5)

Q

15

20 th

25

thirty . 35

45

50

55

From relation (5) it follows that when condition (3) is fulfilled, between the frequency of the tunable oscillator and the measured frequency f there is a linear relationship with the proportionality coefficient N. This allows, firstly, using the frequency f p. Secondly, measurements of an unknown frequency; secondly, by changing N, it is possible to change the units of measurement of the physical quantity X or, using the same meter, measure various physical quantities. convenient units ..

The device operates in two cycles (the first measuring cycle, and the second - corrective).

In the measurement cycle, oscillations from the sensor are fed to information bus 1 (FIG. 1). A shaper of 3 pulses from input oscillations (Fig. 2a) generates square pulses (Fig. 2b) of a duration equal to or a multiple of the half-period of the measured frequency. These pulses through the second key 5, to the control input of which the enabling signal is fed from the synchronizer 18, arrive at the circuit OR 6 and. The third key 7 is closed and the pulses (Fig. 2c) from the controlled generator 16 are fed to a scaling circuit 8 with an adjustable scaling factor, having a scaling factor N. After receiving at its input N pulses at the output an impulse appears, setting trigger 9 into one state (fig. 2d). By cutting the pulses of the pulse generator 3 (Fig. 26), the trigger 9 returns to the initial state.

FIG. Figure 2 shows the case when condition (3) is not fulfilled: the duration of the measurement interval is longer than the time during which N periods of frequency f will pass from the controlled oscillator 16. i.e. Nf ,.

The occurrence of a periodic sequence of pulses at the output of the trigger 9 causes the control voltage to be output at the output of the low-frequency filter 10, which transmits the DC component of the pulsed voltage. This voltage by the control signal generator 11 is converted into a control signal and, (FIG. 2d), which through the fourth switch 12 and the analogue adder 13 goes to the control input of the controlled generator 16. The frequency of the latter changes to those until condition (5) j is satisfied; in this example, the frequency of the controlled oscillator 16 decreases with, and the duration of the pulses at the output of the trigger 9 decreases and approaches the nominal value (shaded in Fig. 2d). The nominal pulse duration corresponds to the nominal control voltage at the input of the driver 11 of the control signal. If the violation of condition (5) occurs in a different direction (fn), then the duration of the pulses at the output of the flip-flop 9 decreases as compared to the nominal one (shaded in fig. 2d). This leads to a decrease in the voltage component the low-pass filter 10 and, to a change in the voltage sign at the output of the driver 11 of the control signal "Under the action of this voltage, the pulse frequency of the controlled generator 16 rises, which again leads to the fulfillment of the condition (5)"

In the steady state (hold mode), the control generator 16, included in the closed loop of automatic control, automatically tracks the measured frequency. Pulses from the output: the code of the controlled oscillator 16: act on the information display circuit, where the physical quantity x is controlled, is displayed in the selected units of measure.

If necessary, change the units

measurement or in the transition to the measurement of another physical quantity changes the conversion factor of the recalculation circuit 8 with the adjustment of the conversion factor. In fig 1 this

It is shown conditionally as switching of a single input of the trigger 9 to another output of the recalculation circuit 8 with an adjustable conversion factor,

 To improve the accuracy of measurements, the controlled oscillator 16 is periodically adjusted by the generator 2 reference pulses. To do this, in the corrective tact of the device 0 5 O

five

P

five

0

five

The second and fourth keys 5 and 12 open, and the first and fifth keys 4 and 15 close. In this case, the generator of 2 reference pulses is turned on in the closed loop of automatic regulation. If the frequency of the pulses of the controlled oscillator 16 is different from the calibration value, the correction signal generator 14 generates and remembers the voltage UK (Fig. 2e), which, through an analog adder 13 on the controlled oscillator 16, returns its frequency to the calibration value.

The subsequent measuring cycle of the device operation takes place with the participation of the correction voltage 11, which continues to affect the control generator 16 through an analog adder 13. As a result, the frequency of the generator 16 is controlled by the total voltage U in the measurement cycle (Fig. 2e),

Claims (1)

Invention Formula A low-frequency sensor signal meter, containing an information bus, a generator of pulse pulses, the output of which is connected to the input of the first key, the output of which is connected to the first input of the OR element, the second input of which is connected to the output of the second key and - characterized by the fact that, in order to improve measurement accuracy and enhancement of functionality, the third, fourth and fifth keys are introduced into it, a recalculation scheme with an adjustable conversion factor, a trigger, no filter control signal shaper, analog adder, correction signal shaper, information display circuit and synchronizer, the first output of which is connected to the control inputs of the first and fifth keys, and the second output - to the control inputs of the second and fourth keys, information bus connected to the input of the pulse generator, the output of which is connected to the input of the second key, the output of the OR element is connected to the reset input of the trigger and the control input of the third key, the output of which is through a scaling circuit - with adjustable conversion factor connected to the trigger setup input, the output of which is connected via a low-pass filter connected in series to the control signal shaper - and the fourth key is connected to the first input of an analog adder whose output is connected to the input of a controlled or controlled pulse generator, / / and. 7 The output of which is connected to the input of the third key and the input of the information display circuit, while the output of the low-pass filter is connected to the second input of the analog adder via the fifth key connected in series and the correction signal generator. but