CN114280522A - Pulse counting calibration device and method for pulse counter - Google Patents

Abstract

The invention discloses a pulse counter pulse counting calibration device and a calibration method, comprising a function/arbitrary waveform generator; the signal output end of the function/arbitrary waveform generator is connected with a signal input end of an adapter, and the signal output end of the adapter is connected with The positive terminal of the signal input terminal of the pulse counter is connected to the negative terminal; the pulse train function of the function/arbitrary waveform generator is used to output a standard pulse voltage signal with a known number of pulses. The standard pulse voltage signal is added to the signal input terminal of the pulse counter; the pulse number measured by the pulse counter is compared with the standard pulse number output by the function/arbitrary waveform generator to calibrate the pulse counter; the calibration of the pulse count of the existing pulse counter is solved. There are many types of standard instruments, high cost, complicated use and calibration, and the output signal amplitude is narrow, which cannot meet the technical problems that the pulse counter requires the amplitude of the input signal.

Description

A pulse counter pulse count calibration device and calibration method

technical field

The invention belongs to the measurement instrument calibration technology, and in particular relates to a pulse counter pulse count calibration device and a calibration method.

Background technique

Pulse counting refers to the cumulative counting of the number of input electrical signals or empty contact signals. The minimum resolution of pulse counting is generally 1, which is dimensionless. Pulse counter is an electronic measuring instrument that can respond to pulse signal or empty contact signal and perform counting measurement. The pulse counter is mainly composed of power supply, internal level trigger circuit, sampling discrimination circuit, counting circuit and display circuit.

The measurement principle block diagram of the pulse counter for measuring the number of pulses of electrical signals is shown in Figure 1. A1 is the positive end of the signal input, A2 is the negative end of the signal input, and the pulses with the required frequency and amplitude are input at the A1 and A2 ends. In the case of a voltage signal, the pulse counter counts and accumulates each pulse.

Figure 2 shows the measurement principle block diagram of the pulse counter for measuring the number of pulses of the empty contact signal. A3 is the positive terminal of the signal input, A4 is the negative terminal of the signal input, and there are voltages at the A3 and A4 terminals and are represented by V1. In order to explain its working principle, an external tact switch K1 is used. When K1 is pressed for the first time, the A3 and A4 terminals are short-circuited, the voltages of the A3 and A4 terminals jump from V1 to 0V, the first pulse is generated at the A3 and A4 terminals, and the pulse counter counts 1 number. When K1 is released for the first time, the A3 and A4 terminals are open, and the voltages of the A3 and A4 terminals jump from 0V to V1. When K1 is pressed for the second time, the A3 and A4 terminals are short-circuited, the voltages of the A3 and A4 terminals jump from V1 to 0V, and the second pulse is generated at the A3 and A4 terminals, and the pulse counter counts and accumulates. When K1 is released for the second time, the A3 and A4 terminals are open, and the voltages of the A3 and A4 terminals jump from 0V to V1. That is, every time K1 is pressed once, the pulse counter counts a number and accumulates it. Since the time spent manually pressing K1 is different from the time interval between two adjacent pressings, the pulse width and pulse interval time are different. The pulse voltage waveforms generated at A3 and A4 terminals are shown in Figure 3.

At present, the specifications for calibrating pulse counters include JJF 1686-2018 "Pulse Counter Calibration Specification", which solves some conventional pulse counter calibration problems, but still has the following shortcomings:

First: the standard instruments used for calibration are: function signal generator, pulse signal generator, general counter with pulse counting function, time interval generator, a total of 4 types of instruments. There are many instruments, high cost, and complicated use and calibration.

Second: JJF 1686-2018 "Pulse Counter Calibration Specification" is suitable for the calibration of pulse counters and pulse counting modules that respond to electrical signals or empty contact signals of 30mV to 10V and measure the number of pulses. At present, there are many pulse counters and pulse counting modules that require the voltage amplitude of the input pulse signal to exceed the range of 30mV to 10V, and some are as high as 50V or more. However, instruments such as function signal generator, pulse signal generator and time interval generator usually have a maximum output pulse voltage peak-to-peak value of 10V under 50Ω output impedance, and a maximum output pulse voltage peak-to-peak value of 20V under high-impedance output impedance. Therefore, they The output signal cannot make the pulse counter and pulse counting module count and cannot be calibrated.

Third: For the pulse counter of the empty contact signal, some of the voltage between the empty contacts exceeds the range of 30mV ~ 10V, and some are as high as 50V or more, such as the use of function signal generators, pulse signal generators, and general-purpose Calibrating 4 types of instruments such as counter and time interval generator will cause damage to the instrument.

At present, the main technical indicators of typical pulse counting are: maximum allowable frequency deviation of built-in time base: ±1.0×10 ^-8 , pulse counting range: 1～1×10 ⁷ , maximum allowable error: ±(maximum allowable frequency deviation of time base ×Pulse count frequency ×measurement time+1).

Due to the variety of existing standard instruments for calibrating pulse counters, high cost, complicated use and calibration, and the parameters such as the output signal amplitude of these instruments cannot meet the input signal requirements of some pulse counters, calibration is difficult. Therefore, calibrating these types of The pulse counter is a difficult problem to solve.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a pulse counter pulse counting calibration device and calibration method to solve the technical problems of the prior art standard instruments such as many types, high cost, narrow output voltage range, and complicated use and calibration.

Technical scheme of the present invention:

A pulse counting calibration device of a pulse counter, comprising a function/arbitrary waveform generator; the signal output end of the function/arbitrary waveform generator is connected with a signal input end of an adapter, and the signal output end of the adapter is connected with the positive end of the signal input end of a pulse counter Connect to the negative terminal; use the pulse train function of the function/arbitrary waveform generator to output a standard pulse voltage signal with a known number of pulses, after being amplified by the adapter, output a standard pulse voltage signal with an adjustable amplitude and a known number of pulses, which is added to The signal input terminal of the pulse counter; the pulse number measured by the pulse counter is compared with the standard pulse number output by the function/arbitrary waveform generator to calibrate the pulse counter.

The adapter includes a transformer B1, one end of the primary winding of the transformer B1 is connected to one end of the switch K1, the other end of the switch K1 is led out to the terminal A5, and the other end of the primary winding of the transformer B1 is led out to the terminal A6; The two ends of the stage winding are respectively connected to the two ends of the AC input of the rectifier bridge D1. The negative end of the 2-way DC output end of the rectifier bridge D1 is connected to the ground GND, and its positive end is connected to the high-frequency capacitor C1, electrolytic capacitor C2, and inductor L1. one end is connected. The other end of the inductor L1 is connected to the high-frequency capacitor C3, the electrolytic capacitor C4, and one end of the resistor R2 and leads to the terminal A8; the other end of the high-frequency capacitor C1, the electrolytic capacitor C2, the high-frequency capacitor C3, and the electrolytic capacitor C4 is connected to the ground GND connected.

One end of the resistor R1 is led out to the terminal A7, the other end of R1 is connected to the base of the NPN transistor Q1, and the emitter of Q1 is connected to the ground GND; a fixed end of the potentiometer W1 is connected to its adjustment end and then connected to the Q1. The collector, a fixed end of the potentiometer W2, and one end of the voltmeter U are connected and led out to the terminal A9; the other fixed end of the potentiometer W2 is connected to its adjustment end and then connected to the ground terminal GND.

The primary and secondary windings of transformer B1 have the same number of turns.

Terminal A8 is a banana jack, and terminals A7 and A9 are BNC type connectors.

Said calibration method of a pulse counter pulse counting calibration device, comprising:

Step 1. Close the switch K1 of the adapter to enable the adapter to work; adjust the potentiometer W1 and potentiometer W2 according to the input signal amplitude requirements of the pulse counter, and observe the voltmeter U at the same time, so that the voltage is within the input voltage range of the pulse counter, and then Disconnect switch K1;

Step 2. Connect the signal output end of the function/arbitrary waveform generator to the signal input end A7 of the adapter with a cable, and connect the signal output end of the adapter to the positive end A10 and the negative end A11 of the signal input end of the pulse counter with a cable, and close the Switch K1 of the adapter;

Step 3. Set the frequency of the output signal of the function/arbitrary waveform generator according to the frequency range of the input signal of the pulse counter;

Step 4. Set the waveform of the output signal of the function/arbitrary waveform generator to pulse wave or sine wave, and set the output signal amplitude according to the input signal amplitude requirements of the adapter;

Step 5. Turn on the pulse train function of the function/arbitrary waveform generator, and set the number of pulses output by the function/arbitrary waveform generator to N ₀ according to the number of pulses to be calibrated;

Step 6. Start the signal output of the function/arbitrary waveform generator, and the pulse counter starts to count; when the number of output pulses reaches N ₀ , the output ends, and the pulse counter stops counting; after reading the number of pulses measured by the pulse counter, clear the pulse counter;

Step 7, repeat step 5 and step 6 twice, calibrate 3 times in total, calculate the average value N _x that the pulse counter measures 3 times;

Step 8. Calculate the pulse count error according to formula (1):

△N=N _x -N ₀ (1)

In the formula: △N is the pulse count error;

N _x is the average value measured by the pulse counter three times;

N ₀ is the number of pulses set by the function/arbitrary waveform generator;

Step 9. Determine whether the pulse count of the pulse counter meets the requirements of the technical indicators. If ΔN is within the maximum allowable error range, it is qualified, otherwise it is unqualified.

Beneficial effects of the present invention:

The present invention consists of 1 switch, 1 transformer, 1 rectifier bridge, 1 inductor, 2 high frequency capacitors, 2 electrolytic capacitors, 2 resistors, 2 potentiometers, 1 NPN type crystal switch transistor and 1 A total of 14 electronic components of the voltmeter constitute an adapter, and the adapter and a function/arbitrary waveform generator constitute a calibration device. Utilize the pulse train function of the function/arbitrary waveform generator to output the required number of pulses and voltage signals. After switching amplification by the adapter, the pulse train voltage signal with adjustable amplitude is output to realize the calibration of the pulse counter.

The invention is simple, reliable and convenient to use. The number of pulses output by the calibration device is adjustable within the range of 1 to 1×10 ⁷ , and the output amplitude is continuously adjustable within the range of 0V to 300V, covering the counting range of the pulse counter and the range of the input voltage. Provided is a solution to the technical problems that the existing pulse counter pulse counting calibration standard instruments have many types, high cost, complicated use and calibration, and the output signal amplitude is narrow, which cannot meet the pulse counter's requirement for the amplitude of the input signal, and solves the problem that the existing technology cannot Calibration techniques for calibrating pulse counts for all types of pulse counters.

Description of drawings:

Fig. 1 is the measurement principle block diagram of the pulse counter that the prior art electric signal carries out the pulse number measurement;

Fig. 2 is the measurement principle block diagram of the pulse counter that the empty contact signal of the prior art carries out the pulse number measurement;

Fig. 3 is the pulse voltage waveform generated when the prior art empty contact signal carries out the pulse number measurement manual switch;

4 is a schematic diagram of the adapter circuit of the present invention;

FIG. 5 is a schematic diagram of the connection of the calibration device of the present invention.

Detailed ways:

A pulse counter pulse counting calibration device includes a function/arbitrary waveform generator and an adapter, and the circuit diagram of the adapter is shown in Figure 4.

One end of the primary winding of the transformer B1 is connected to one end of the switch K1, the other end of the switch K1 is led out to the terminal A5, and the other end of the primary winding of the transformer B1 is led out to the terminal A6. The two ends of the secondary winding of the transformer B1 are connected to the two ends of the AC input of the rectifier bridge D1 respectively. C2, one end of the inductor L1 is connected. The other end of the inductor L1 is connected to the high-frequency capacitor C3, the electrolytic capacitor C4, and one end of the resistor R2, and is led out to the terminal A8. The other ends of the high-frequency capacitor C1, the electrolytic capacitor C2, the high-frequency capacitor C3, and the electrolytic capacitor C4 are connected to the ground GND.

One end of the resistor R1 is led out to the terminal A7, and the other end of the R1 is connected to the base of the NPN transistor Q1, and the emitter of Q1 is connected to the ground terminal GND. A fixed end of the potentiometer W1 is connected to its adjustment end and then connected to the collector of Q1, a fixed end of the potentiometer W2, and one end of the voltmeter U, and is led out to the terminal A9. The other fixed end of the potentiometer W2 is connected to its adjustment end and then connected to the ground end GND.

The AC voltage of 220V and 50Hz is added to the terminals A5 and A6, and after passing through the switch K1, it is added to the primary winding of the transformer B1. The primary winding and the secondary winding of the transformer B1 have the same number of turns, and the transformer B1 acts as an isolation, which isolates the adapter from the power supply grid and improves the safety of electricity use. Therefore, the output of the secondary winding of the transformer B1 is also an AC voltage of 220V and 50Hz. After this voltage is rectified by the rectifier bridge D1, it is filtered by a π-type filter composed of capacitors C1, C2, C3, C4 and inductor L1. A8 terminal outputs a DC voltage of about 300V. Among them, high-frequency capacitors C1 and C3 filter out high-frequency interference, electrolytic capacitors C2 and C4 filter out low-frequency interference and play a smoothing role, and inductor L1 plays a role of choke.

Resistor R1 acts as a current limiter to limit the excessive current flowing through the base of Q1. The resistor R2 acts as a current limiter to prevent the current flowing through the rectifier bridge D1 from being too large when the resistance values of the potentiometer W1 and the potentiometer W2 are both adjusted to the minimum value of 0Ω. Q1 works in the cut-off or saturated conduction state, and plays the role of switching and amplifying. Potentiometers W1 and W2 are used to adjust the amplitude of the output signal, and the voltmeter U is used to monitor the voltage amplitude of the output signal.

Terminal A8 is a banana jack, and terminals A7 and A9 are BNC type connectors.

The calibration connection block diagram is shown in Figure 5. The output end of the function/arbitrary waveform generator is connected to the signal input end A7 of the adapter, and the signal output end A9 of the adapter is connected to the positive end A10 and the negative end A11 of the signal input end of the pulse counter.

The working principle of calibration is to use the pulse train function of the function/arbitrary waveform generator to output a standard pulse voltage signal with a known number of pulses. to the signal input of the pulse counter. The number of pulses measured by the pulse counter is compared with the standard number of pulses output by the function/arbitrary waveform generator, so as to judge whether the pulse counter meets its technical specifications.

Close the switch K1 to make the adapter energized and work, then the terminal A8 has a DC voltage of about 300V. Adjust potentiometer W1 and potentiometer W2 according to the input signal amplitude requirements of the calibrated pulse counter, and observe the voltmeter U at the same time, so that the displayed voltage value V2 is within the input voltage range of the pulse counter. According to the input signal frequency range of the pulse counter, set the frequency of the output signal of the function/arbitrary waveform generator, and set the low level of the output signal amplitude to 0V and the high level to 1V. Use the burst function of the function/arbitrary waveform generator to set the number of pulses to be calibrated. The pulse signal is applied to the base of the NPN transistor Q1 through the terminals A7 and R1. A low level of 0V turns off Q1, and the collector of Q1 outputs a high level of V2; a high level of 1V makes Q1 saturated and turned on, and the collector of Q1 outputs a low level of 0V. The input waveform of the A7 terminal and the output waveform of the A9 terminal are shown in Figure 4 shown in. Q1 works in a saturated on or off state, which is equivalent to turning on and off. Therefore, whether the output terminal A9 of the adapter is connected to a pulse counter for measuring the number of pulses of an electrical signal, a pulse counter for measuring the number of pulses of an empty contact signal, or a pulse counting module, it can count the pulses, so as to realize the counting of its pulses. calibration.

A method for calibrating the pulse count of a pulse counter includes:

Step 1. Close the switch K1 of the adapter to enable the adapter to work; adjust the potentiometer W1 and potentiometer W2 according to the input signal amplitude requirements of the pulse counter, and observe the voltmeter U at the same time, so that the voltage is within the input voltage range of the pulse counter, and then Disconnect switch K1;

Step 2. Connect the signal output end of the function/arbitrary waveform generator to the signal input end A7 of the adapter with a cable, and connect the signal output end of the adapter to the positive end A10 and the negative end A11 of the signal input end of the pulse counter with a cable, and close the Switch K1 of the adapter;

Step 3. Set the frequency of the output signal of the function/arbitrary waveform generator according to the frequency range of the input signal of the pulse counter;

Step 4. Set the waveform of the output signal of the function/arbitrary waveform generator to pulse wave or sine wave, and set the output signal amplitude according to the input signal amplitude requirements of the adapter;

Step 5. Turn on the pulse train function of the function/arbitrary waveform generator, and set the number of pulses output by the function/arbitrary waveform generator to N ₀ according to the number of pulses to be calibrated;

Step 6. Start the signal output of the function/arbitrary waveform generator, and the pulse counter starts counting. When the number of output pulses reaches N ₀ , the output ends and the pulse counter stops counting. After reading the number of pulses measured by the pulse counter, clear the pulse counter;

Step 7, repeat step 5 and step 6 twice, calibrated 3 times in total, calculate the average value N _x that the pulse counter measures 3 times;

Step 8. Calculate the pulse count error according to formula (1);

△N=N _x -N ₀ (1)

In the formula: △N is the pulse count error;

N _x is the average value measured by the pulse counter three times;

N ₀ is the number of pulses set by the function/arbitrary waveform generator;

Step 9. Determine whether the pulse count of the pulse counter meets the requirements of technical indicators: if △N is within its maximum allowable error range, it is qualified, otherwise it is unqualified.

The function/arbitrary waveform generator used in this embodiment is a 33250A type function/arbitrary waveform generator produced by Keysight, and the output waveforms include sine wave, square wave, pulse wave, ramp wave, arbitrary wave and the like. Optional built-in time base with a maximum allowable frequency deviation of ±1.0×10 ^-9 ; output frequency range: 1μHz～80MHz; output amplitude range when output impedance is 50Ω: 10mVpp～10Vpp; output pulse number range: 1～1×10 ⁷ ; With external reference frequency standard input port.

Take the calibration of the H7EC-NVF pulse counter produced by OMRON as an example to illustrate.

H7EC-NVF type pulse counter, its main technical indicators are: input pulse signal voltage range: 24V ~ 240V, input pulse signal frequency range: 0Hz ~ 1kHz, pulse count range: 1 ~ 99999999.

The method of setting the number of output pulses with the 33250A function/arbitrary waveform generator is as follows:

The output frequency is 1kHz, the amplitude is 1V, and the number of pulses is 10000. Press the pulse key (Pulse) on the front panel, in the Pulse menu, set the frequency (Freq) to 1kHz, the amplitude (Ample) high level to 1V, the low level to 0V, and the offset (Offset) to 0.5V. Press the burst key (Burst) on the front panel, set the number of output pulses (NCycle) to 10000 in the Burst menu, set the trigger mode setting (Trigger Setup) to manual trigger (Manual), and press to confirm the setting (Done). Press the Output key on the front panel to turn on the output. Then every time you press the trigger button (Trigger) on the front panel, the output terminal (Output) on the front panel outputs a pulse voltage signal with a high level of 1V, a low level of 0V and a pulse number of 10000.

The adapter is set up as follows:

Select any point within the input pulse signal voltage range of 24V to 240V for the H7EC-NVF pulse counter, such as 200V as an example to set the adapter. Adjust the potentiometers W1 and W2 of the adapter so that the voltmeter U shows 200V.

After following the steps of the above calibration method, the signal output terminal A9 of the adapter outputs a pulse signal with a frequency of 1kHz and a voltage amplitude of 200V. This signal can make the H7EC-NVF pulse counter count, thereby realizing its calibration.

The main technical indicators of the calibration device:

The maximum allowable frequency deviation of the built-in time base: ±1.0×10 ^-9 , the output frequency range: 1μHz～80MHz, and the output voltage range: 0V～300V. Output pulse number range: 1～1×10 ⁷ . The function/arbitrary waveform generator has an external reference frequency standard input port, and can use an external reference frequency standard with higher precision, such as rubidium atomic frequency standard, cesium atomic frequency standard, etc., to increase the maximum allowable frequency deviation of the time base to: ±( 1 × 10 ^-10 ~ 1.0 × 10 ^-12 ) order, thereby greatly improving the accuracy of the number of output pulses.

Claims (6)

1. A pulse counter pulse count calibration apparatus includes a function/arbitrary waveform generator; the method is characterized in that: the signal output end of the function/arbitrary waveform generator is connected with the signal input end of the adapter, and the signal output end of the adapter is connected with the positive end and the negative end of the signal input end of the pulse counter; the pulse string function of the function/arbitrary waveform generator is utilized to output a standard pulse voltage signal with known pulse number, the standard pulse voltage signal with known pulse number and adjustable amplitude is output after being amplified by the adapter, and the standard pulse voltage signal is added to the signal input end of the pulse counter; the pulse number measured by the pulse counter is compared with the standard pulse number output by the function/arbitrary waveform generator to calibrate the pulse counter.

2. The pulse counter pulse count calibration device of claim 1, wherein: the adapter comprises a transformer B1, one end of a primary winding of the transformer B1 is connected to one end of a switch K1, the other end of the switch K1 is led out to a terminal A5, and the other end of the primary winding of the transformer B1 is led out to a terminal A6; two ends of a secondary winding of the transformer B1 are respectively connected to two ends of an alternating current input of the rectifier bridge D1, a negative end of a 2-path direct current output end of the rectifier bridge D1 is connected to the ground GND, and a positive end of the 2-path direct current output end is connected with one end of the high-frequency capacitor C1, one end of the electrolytic capacitor C2 and one end of the inductor L1. The other end of the inductor L1 is connected with one end of a high-frequency capacitor C3, an electrolytic capacitor C4 and a resistor R2 and is led out to a terminal A8; the other ends of the high-frequency capacitor C1, the electrolytic capacitor C2, the high-frequency capacitor C3 and the electrolytic capacitor C4 are connected to the ground GND.

3. The pulse counter pulse count calibration device of claim 1, wherein: one end of the resistor R1 is led out to a terminal A7, the other end of the resistor R1 is connected with the base electrode of an NPN type transistor Q1, and the emitter electrode of the transistor Q1 is connected to the ground end GND; a fixed end of the potentiometer W1 is connected with the adjusting end thereof and then connected with a collector of Q1, a fixed end of the potentiometer W2 and one end of the voltmeter U, and is led out to a terminal A9; the other fixed end of the potentiometer W2 is connected to the adjustment end thereof and then connected to the ground GND.

4. The pulse counter pulse count calibration device of claim 1, wherein: the number of turns of the primary winding and the secondary winding of the transformer B1 is the same.

5. The pulse counter pulse count calibration device of claim 1, wherein: terminal A8 is a banana jack and terminals a7 and a9 are BNC style connectors.

6. A method of calibrating a pulse counter pulse count calibration apparatus according to claim 1, comprising:

step 1, closing a switch K1 of the adapter to electrify the adapter to work; according to the amplitude requirement of the input signal of the pulse counter, the potentiometer W1 and the potentiometer W2 are adjusted, a voltmeter U is observed at the same time, the voltage is enabled to be within the input voltage range of the pulse counter, and then the switch K1 is disconnected;

step 2, connecting the signal output end of the function/arbitrary waveform generator with a signal input end A7 of the adapter by a cable, connecting the signal output end of the adapter with a positive end A10 and a negative end A11 of the signal input end of the pulse counter by the cable, and closing a switch K1 of the adapter;

step 3, setting the frequency of the output signal of the function/arbitrary waveform generator according to the frequency range of the input signal of the pulse counter;

step 4, setting the waveform of the output signal of the function/arbitrary waveform generator as a pulse wave or a sine wave, and setting the amplitude of the output signal according to the amplitude requirement of the input signal of the adapter;

step 5, starting the pulse train function of the function/arbitrary waveform generator, and setting the number of pulses output by the function/arbitrary waveform generator to be N according to the number point of the pulses to be calibrated₀；

Step 6, starting signal output of the function/arbitrary waveform generator, and starting counting by a pulse counter; when the number of output pulses reaches N₀When the output is finished, the pulse counter stops counting; after the number of pulses measured by the pulse counter is read, the pulse counter is cleared;

step 7, repeating the step 5 and the step 6 twice, calibrating for 3 times, and calculating the average value N measured by the pulse counter for 3 times_x；

And 8, calculating a pulse counting error according to the formula (1):

△N＝N_x-N₀ (1)

in the formula: Δ N is the pulse count error;

N_xthe average value of 3 times of measurement of the pulse counter is obtained;

N₀number of pulses set for function/arbitrary waveform generator;

and 9, judging whether the pulse counting of the pulse counter meets the technical index requirement, if the Delta N is within the maximum allowable error range, the pulse counter is qualified, and if not, the pulse counter is unqualified.

Images