CN201004079Y - A frequency measurement and frequency accompanying circuit - Google Patents
A frequency measurement and frequency accompanying circuit Download PDFInfo
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- CN201004079Y CN201004079Y CNU2005200367197U CN200520036719U CN201004079Y CN 201004079 Y CN201004079 Y CN 201004079Y CN U2005200367197 U CNU2005200367197 U CN U2005200367197U CN 200520036719 U CN200520036719 U CN 200520036719U CN 201004079 Y CN201004079 Y CN 201004079Y
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Abstract
The utility model provides a frequency measuring and frequency tracking circuit, belonging to the electronic technical field, relating to the frequency measuring technical field, which is essentially applicable to the frequency measuring and the frequency tracking of the periodic alternating current circuit with a frequency below 60 Hz. The whole circuit consists of a signal sampling circuit, a low pass filtering circuit, an impulse shaping circuit and a doubling circuit connected orderly. The measured low frequency signal realizes filtering through the filtering circuit after passing the signal sampling circuit; the filtered low frequency sampling signal is changed into a square wave impulse signal synchronous with the measured low frequency signal frequency through the impulse shaping circuit; and then the square wave impulse signal is finally transferred into the required doubling impulse output signal through the doubling circuit. By use of the frequency measuring and frequency tracking circuit, the utility model is able to measure the low frequency signal frequency quickly and accurately; and meantime, as taking the output signal of the circuit as the sampling signal of the sampling circuit, the utility model achieves the aim of frequency tracking, thereby ensuring the sampling precision in the frequency changing of the periodic measured signal.
Description
Technical field
A kind of frequency measurement and frequency follow circuit belong to electronic technology field, relate to the frequency measurement technical field, are mainly used in 60Hz is followed with the frequency measurement and the frequency of the periodicity alternating circuit of lower frequency.
Background technology
At present, all adopt the method for Direct Sampling at the circuit that the periodicity AC signal is sampled, promptly adopt the sampled signal of fixed frequency that the periodicity AC signal is sampled, sampling number is identical in the unit interval.When the frequency of measured periodicity AC signal changed, can make that signals sampling is counted in each cycle to change: when the measured signal frequency reduced, the sampling number in the one-period can increase; When the measured signal frequency increased, the sampling number in the one-period just reduced.
Effective value to periodic signal calculates, and what generally adopt all is the method for the approximate reduction of fixed sample point, and the principal feature of this algorithm is that computing is simple, and shortcoming is to require the sampling number in a measured signal cycle to fix.If take place in the measured signal frequency can not guarantee that the sampling number in one-period remains unchanged under the situation of fluctuation, also just can not guarantee sampling precision in this case.
In addition, in the method for measuring the low frequency signal frequency, generally adopt traditional survey week method, the time of promptly measuring a cycle.Its principle of work promptly picks up counting at the starting point t1 from one-period as shown in Figure 1, finishes timing to the starting point t2 in next cycle, calculates the frequency of measured signal by the mistiming of calculating t1-t2.In the circuit design of reality, want very accurately to be difficult to accomplish that for the signal period therefore adopt the method measuring-signal frequency of surveying week, its precision is lower less than 1 second signal at the one-period clocking internal.
A kind of method of measuring the low frequency signal frequency is arranged in addition, i.e. pulse counting method, its principle of work such as Fig. 2.Longer again for precision institute's time spent of having only signal about 50 hertz to want to reach higher as this frequency of 220V alternating current, be difficult to the accurately real-time frequency situation of change of reflection measured signal, if wanting measuring accuracy, we reach 1/1024, then need to spend 20.48 seconds, this is obviously oversize for a real-time system.
Summary of the invention
The utility model provides a kind of circuit, and it can measure the low frequency signal frequency quickly and accurately; Simultaneously,, the purpose that frequency is followed can be reached, still sampling precision can be guaranteed thereby can be implemented in when periodically the measured signal frequency changes if adopt the sampled signal of the output signal of sort circuit as sample circuit.
The utility model detailed technology scheme is:
A kind of frequency measurement and frequency follow circuit as shown in Figure 3, comprise signal sample circuit, low-pass filter circuit, pulse shaping circuit and frequency multiplier circuit.Described signal sample circuit is sampled to tested low frequency signal; Described low-pass filter circuit carries out filtering to the sampled signal of tested low frequency signal, rejects the high frequency interference in the measured signal; Described pulse shaping circuit becomes square-wave pulse signal with tested low frequency signal Frequency Synchronization to the sampled signal through filtered tested low frequency signal; Described frequency multiplier circuit becomes the low-frequency square-wave pulse of being sent into by pulse shaping circuit the double frequency pulse output signal that needs.This frequency measurement and frequency follow circuit are characterised in that described signal sample circuit, low-pass filter circuit, pulse shaping circuit and frequency multiplier circuit link to each other successively.
Described signal sample circuit is the signal follow circuit, as shown in Figure 5, is made of resistance (Rv1, R2, R3, R105, R59, R34 and R32), voltage transformer (VT) TV1 and operational amplifier DA; Tested low frequency signal is received sampling resistor Rv1 two ends, by voltage transformer (VT) TV1 AC signal is coupled in the metering circuit, carries out current limliting according to the size change resistance R 2 of measured signal and the value of R3; Resistance R 105 also is a sampling resistor, and it becomes voltage signal to current signal; Constitute the signal follow circuit by operational amplifier DA and resistance (R32, R34, R59), its effect is to improve input impedance, reduces the influence of circuit internal driving to input signal.
Described low-pass filter circuit is a second-order low-pass filter, is made of operational amplifier DB, resistance (R38, R46 and R47) and electric capacity (C6, C7), and it mainly acts on is high-frequency harmonic in the filtering input signal, avoids harmonic signal to influence follow-up output pulse.
Described pulse shaping circuit is made of operational amplifier DC, resistance (R54, R55, R56, R57 and R58), diode (V9, V10), capacitor C 18 and phase inverter D1; Wherein, operational amplifier DC and resistance (R54, R55, R56, R57 and R58) constitute the zero balancing circuit, the AC signal of input is become dc pulse signal, resistance R 58 output high level when input signal is in positive half cycle, resistance R 58 output zero levels when input signal is in negative half period; Diode (V9, V10) plays a voltage amplitude limit, input voltage is limited in the Transistor-Transistor Logic level scope of 0-5V; By phase inverter D1 input signal is carried out the square-wave pulse that shaping becomes standard.
Described frequency multiplier circuit can be exported the signal of 2 frequencys multiplication of input signal to 2048 frequencys multiplication as required by being the phase-locked loop circuit of core with phase-locked loop circuit MC4046 and being that the counter circuit of core is formed with counter MC4020.
Because measured signal is the driving source of entire circuit, therefore, it can accomplish that also good frequency follows effect in circuit described in the utility model.When it is used in frequency measurement since it the highest can frequency multiplication to 2048 times of measured signal, so its frequency test precision can reach 1/2048, and the time only needs the time of a cycle.If the sampled signal of the output signal after the frequency multiplication as alternating current sampling circuit, because it is come out by the measured signal frequency multiplication, the frequency of sampling pulse can change with the frequency change of then measured signal, therefore the sampling number to each cycle can not change because of the frequency change of measured signal, thereby has guaranteed the independence of measuring accuracy and signal frequency.
The beneficial effects of the utility model are: utilize frequency measurement of the present invention and frequency follow circuit, can measure the low frequency signal frequency quickly and accurately; Simultaneously,, the purpose that frequency is followed can be reached, still sampling precision can be guaranteed thereby can be implemented in when periodically the measured signal frequency changes if adopt the sampled signal of the output signal of sort circuit as sample circuit.
Description of drawings
Fig. 1 is a schematic diagram of surveying all method measuring-signal frequencies.
Fig. 2 is the schematic diagram of pulse counting method measuring-signal frequency.
Fig. 3 is the theory diagram of frequency measurement described in the utility model and frequency follow circuit.
Fig. 4 is the circuit diagram of frequency measurement described in the utility model and frequency follow circuit.
Fig. 5 is the signal sample circuit figure of frequency measurement described in the utility model and frequency follow circuit.
Fig. 6 is the low-pass filter circuit and the pulse shaping circuit figure of frequency measurement described in the utility model and frequency follow circuit.
Fig. 7 is the frequency multiplier circuit figure of frequency measurement described in the utility model and frequency follow circuit.
Embodiment
A kind of frequency measurement and frequency follow circuit as shown in Figure 3, Figure 4, comprise signal sample circuit, low-pass filter circuit, pulse shaping circuit and frequency multiplier circuit.Described signal sample circuit, low-pass filter circuit, pulse shaping circuit and frequency multiplier circuit link to each other successively.Described signal sample circuit is sampled to tested low frequency signal; Described low-pass filter circuit carries out filtering to the sampled signal of tested low frequency signal, rejects the high frequency interference in the measured signal; Described pulse shaping circuit becomes square-wave pulse signal with tested low frequency signal Frequency Synchronization to the sampled signal through filtered tested low frequency signal; Described frequency multiplier circuit becomes the low-frequency square-wave pulse of being sent into by pulse shaping circuit the double frequency pulse output signal that needs.
Described signal sample circuit is made of seven resistance, a voltage transformer (VT) TV1 and an operational amplifier DA as shown in Figure 5; Primary coil by the first sampling resistor Rv1, the first current-limiting resistance R2, the second current-limiting resistance R3 and voltage transformer (VT) TV1 constitutes the closed-loop path, and tested low frequency signal is received sampling resistor Rv1 two ends; An end ground connection behind the parallel connection of secondary windings of the second sampling resistor R105 and voltage transformer (VT) TV1, the other end connects the forward end of operational amplifier DA by the 5th resistance R 59, the negative end of operational amplifier DA connects its output terminal by the 6th resistance R 34, and the output terminal of operational amplifier DA is by the 7th resistance R 32 output sampled signals.
Described low-pass filter circuit is a second-order low-pass filter as shown in Figure 6, is made of an operational amplifier DB, two resistance and two electric capacity; The sampled signal of sample circuit output connects the forward end of operational amplifier DB by first resistance R 38, connects the output terminal of operational amplifier DB simultaneously by first capacitor C 7; The negative end of operational amplifier DB connects the output terminal of operational amplifier DB simultaneously by second resistance R, 46 ground connection by the 3rd resistance R 47; The output terminal output low-pass filter signal of operational amplifier DB.
Described pulse shaping circuit is made of an operational amplifier DC, five resistance, two limiter diodes, a capacitor C 18 and a phase inverter D1 as shown in Figure 6.Wherein, operational amplifier DC and five resistance constitute the zero balancing circuit: low-pass filter signal connects the forward end of operational amplifier DC by first resistance R 54; The forward end of operational amplifier DC links to each other with the 5th resistance (R58) by second resistance R 55, and its negative end is by the 3rd resistance R 56 ground connection, and its output terminal connects the tie point of second resistance R 55 and the 5th resistance R 58 by the 4th resistance R 57; The other end of the 5th resistance R 58 is as the signal output part of zero balancing circuit.The signal output part of zero balancing circuit connects the input end of phase inverter D1, simultaneously by capacitor C 18 ground connection; The positive pole of the input termination first limiter diode D9 of phase inverter D1, the negative pole of the first limiter diode D9 connect+5 volts of power supplys; Simultaneously, the negative pole of the input termination second limiter diode D10 of phase inverter D1, the plus earth of the second limiter diode D10.
Described frequency multiplier circuit as shown in Figure 7, by being the phase-locked loop circuit of core with phase-locked loop circuit MC4046 and being that the counter circuit of core constitutes with counter MC4020.
Each element circuit and main element functional interpretation are as follows among Fig. 4-Fig. 7:
Among Fig. 4 by DA, DB, the analog quantity of DC execution cycle simulating signal is to the conversion of digital quantity, its function is the pulse signal that the cycle analog quantity is converted to same period.D15 is counter MC4020, and D16 is phase-locked loop circuit MC4046, forms frequency multiplier circuit by D15 and D16, can be according to 2,4 of input signal by this circuit, 8,16,32,64,128,256,512,1024,2048 overtones bands are exported pulse, as long as required from the Q11 of D15, and Q10, Q9, Q8, Q7, Q6, Q5, Q4, Q3, Q2, the Q1 number of winning the confidence.Because input signal comes from and is sampled signal, therefore when enabling signal that the output of Q11-Q1 is sampled as AD, with regard to having accomplished the frequency of sampled signal to be followed. this moment is when the external signal frequency changes, signal sampling point in each cycle can remain unchanged. consequently when being sampled the bigger variation of signal frequency generation, can not produce extra measuring error.
Among Fig. 5, TV1 is a voltage transformer (VT), and it is responsible for AC signal is coupled in the metering circuit, carries out current limliting according to the size change R2 of measured signal and the value of R3; R105 is a sampling resistor, and it becomes voltage signal to current signal; By DA, R32, R34, R59 constitutes the signal follow circuit, and its effect is to improve input impedance, reduces the influence of circuit internal driving to input signal.
Among Fig. 6, by DB, R38, R46, R47, C6, C7 constitutes second-order low-pass filter, and it mainly acts on is high-frequency harmonic in the filtering input signal, avoids harmonic signal to influence follow-up output pulse.
Among Fig. 6, by DC, R54, R55, R56, R57, R58 constitutes the zero passage comparator circuit, its effect is that the AC signal of input is become dc pulse signal, and its principle of work is a R58 place output high level when input signal is in positive half cycle, R58 place output zero level when input signal is in negative half period.
Among Fig. 6, V9, V10 play a voltage amplitude limit, can be limited in input voltage in the Transistor-Transistor Logic level scope of 0-5V by it, and the effect of D1 is that input signal is carried out the square-wave pulse that shaping becomes standard.
Frequency multiplier circuit shown in Figure 7 is by being the phase-locked loop circuit of core with D16 and being that the counter circuit of core is formed with D15, and it makes signal by the IN input with input signal 2-2048 frequency output pulse signal doubly.Its principle of work is as follows:
Characteristics of phase-locked loop circuit are, can make output signal consistent with frequency input signal, therefore such as the signal frequency of the AIN terminal of input D16 is 50HZ, if the BIN signal frequency of input is less than 50HZ, then D16 will improve the output frequency of VOUT terminal, because VOUT is connected on the CLK end of counter D15, and BIN is connected on the Q12 end of D15, according to the principle of work of counter, if want the pulse of Q12 output 50HZ, the incoming frequency of CLK is necessary for 200KHZ, the output frequency of VOUT can be adjusted to 200KHZ automatically, this moment, the output frequency of Q11-Q1 was respectively 100HZ, 200HZ, 400HZ ... 100KHZ.Therefore, can be as required from Q1-Q11, select the frequency of needs to use, and this frequency be signal frequency 2 Nth power doubly.
Claims (5)
1, a kind of frequency measurement and frequency follow circuit comprise signal sample circuit, low-pass filter circuit, pulse shaping circuit and frequency multiplier circuit; Tested low frequency signal after the sampling of described signal sample circuit by described low-pass filter circuit filtering, filtered signal is shaped as square-wave pulse signal with tested low frequency signal Frequency Synchronization by described pulse shaping circuit again, and the square-wave pulse signal after the shaping becomes the double frequency pulse output signal that needs through described frequency multiplier circuit; It is characterized in that described signal sample circuit, low-pass filter circuit, pulse shaping circuit and frequency multiplier circuit link to each other successively.
2, a kind of frequency measurement according to claim 1 and frequency follow circuit is characterized in that, described signal sample circuit is made of seven resistance, a voltage transformer (VT) (TV1) and an operational amplifier (DA); Primary coil by first sampling resistor (Rv1), first current-limiting resistance (R2), second current-limiting resistance (R3) and voltage transformer (VT) (TV1) constitutes the closed-loop path, and tested low frequency signal is received sampling resistor (Rv1) two ends; An end ground connection behind the parallel connection of secondary windings of second sampling resistor (R105) and voltage transformer (VT) (TV1), the other end connects the forward end of operational amplifier (DA) by the 5th resistance (R59), the negative end of operational amplifier (DA) connects its output terminal by the 6th resistance (R34), and the output terminal of operational amplifier (DA) is by the 7th resistance (R32) output sampled signal.
3, a kind of frequency measurement according to claim 1 and frequency follow circuit is characterized in that, described low-pass filter circuit is a second-order low-pass filter, are made of an operational amplifier (DB), two resistance and two electric capacity; The sampled signal of sample circuit output connects the forward end of operational amplifier (DB) by first resistance (R38), connects the output terminal of operational amplifier (DB) simultaneously by first electric capacity (C7); The negative end of operational amplifier (DB) connects the output terminal of operational amplifier (DB) simultaneously by second resistance (R46) ground connection by the 3rd resistance (R47); The output terminal output low-pass filter signal of operational amplifier (DB).
4, a kind of frequency measurement according to claim 1 and frequency follow circuit, it is characterized in that described pulse shaping circuit is made of an operational amplifier (DC), five resistance, two limiter diodes, an electric capacity (C18) and phase inverters (D1);
Wherein, operational amplifier (DC) and five resistance constitute the zero balancing circuit: low-pass filter signal connects the forward end of operational amplifier (DC) by first resistance (R54); The forward end of operational amplifier (DC) links to each other with the 5th resistance (R58) by second resistance (R55), its negative end is by the 3rd resistance (R56) ground connection, and its output terminal connects the tie point of second resistance (R55) and the 5th resistance (R58) by the 4th resistance (R57); The other end of the 5th resistance (R58) is as the signal output part of zero balancing circuit;
The signal output part of zero balancing circuit connects the input end of phase inverter (D1), simultaneously by electric capacity (C18) ground connection; The positive pole of input termination first limiter diode (D9) of phase inverter (D1), the negative pole of first limiter diode (D9) connect+5 volts of power supplys; Simultaneously, the negative pole of input termination second limiter diode (D10) of phase inverter (D1), the plus earth of second limiter diode (D10).
5, a kind of frequency measurement according to claim 1 and frequency follow circuit, it is characterized in that, described frequency multiplier circuit is by being the phase-locked loop circuit of core with phase-locked loop circuit MC4046 and being that the counter circuit of core is formed with counter MC4020 that its output signal is the signals of 2 frequencys multiplication of input signal to 2048 frequencys multiplication.
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| CNU2005200367197U CN201004079Y (en) | 2005-12-29 | 2005-12-29 | A frequency measurement and frequency accompanying circuit |
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| CNU2005200367197U CN201004079Y (en) | 2005-12-29 | 2005-12-29 | A frequency measurement and frequency accompanying circuit |
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Cited By (11)
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| CN102109552A (en) * | 2010-12-14 | 2011-06-29 | 广东大普通信技术有限公司 | High-frequency and high-speed frequency testing system and method based on phase locking technique |
| CN101871968B (en) * | 2009-04-24 | 2011-12-07 | 郑州威科姆科技股份有限公司 | Reliable time scale pulse measurement method and measurement device thereof |
| CN102590614A (en) * | 2012-03-16 | 2012-07-18 | 无锡鑫立奥机电有限公司 | Detection system and detection method of ultrasonic frequency |
| CN103138718A (en) * | 2011-11-24 | 2013-06-05 | 中国北车股份有限公司大连电力牵引研发中心 | Device and method for processing signals and electric locomotive |
| CN103178845A (en) * | 2013-03-04 | 2013-06-26 | 安徽省电力公司宣城供电公司 | Phase-locked loop and method for measuring voltage phase and frequency |
| CN105628953A (en) * | 2016-01-13 | 2016-06-01 | 中国航空动力机械研究所 | Aero-engine dynamic test system, frequency-voltage transformation circuit and method |
| CN105656447A (en) * | 2014-12-05 | 2016-06-08 | 王丽香 | Ultra-low frequency signal filtering-amplifying-shaping circuit |
| CN106405231A (en) * | 2016-08-31 | 2017-02-15 | 无锡小天鹅股份有限公司 | Household electrical appliance and power source frequency detection method and apparatus therefor |
| CN107238755A (en) * | 2017-05-27 | 2017-10-10 | 何永平 | The resonant frequency measurement method and measuring system resonator of a kind of oscillator |
| CN112710897A (en) * | 2020-12-07 | 2021-04-27 | 广东电网有限责任公司韶关供电局 | Frequency measuring circuit |
| CN115173558A (en) * | 2022-07-15 | 2022-10-11 | 国网江苏省电力有限公司 | New forms of energy station yard on-line measuring system |
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- 2005-12-29 CN CNU2005200367197U patent/CN201004079Y/en not_active Expired - Fee Related
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101871968B (en) * | 2009-04-24 | 2011-12-07 | 郑州威科姆科技股份有限公司 | Reliable time scale pulse measurement method and measurement device thereof |
| CN102109552B (en) * | 2010-12-14 | 2013-07-31 | 广东大普通信技术有限公司 | High-frequency and high-speed frequency testing system and method based on phase locking technique |
| CN102109552A (en) * | 2010-12-14 | 2011-06-29 | 广东大普通信技术有限公司 | High-frequency and high-speed frequency testing system and method based on phase locking technique |
| CN103138718B (en) * | 2011-11-24 | 2016-08-31 | 中国北车股份有限公司 | Signal processing apparatus, processing method and electric locomotive |
| CN103138718A (en) * | 2011-11-24 | 2013-06-05 | 中国北车股份有限公司大连电力牵引研发中心 | Device and method for processing signals and electric locomotive |
| CN102590614A (en) * | 2012-03-16 | 2012-07-18 | 无锡鑫立奥机电有限公司 | Detection system and detection method of ultrasonic frequency |
| CN103178845A (en) * | 2013-03-04 | 2013-06-26 | 安徽省电力公司宣城供电公司 | Phase-locked loop and method for measuring voltage phase and frequency |
| CN105656447A (en) * | 2014-12-05 | 2016-06-08 | 王丽香 | Ultra-low frequency signal filtering-amplifying-shaping circuit |
| CN105628953A (en) * | 2016-01-13 | 2016-06-01 | 中国航空动力机械研究所 | Aero-engine dynamic test system, frequency-voltage transformation circuit and method |
| CN105628953B (en) * | 2016-01-13 | 2019-08-06 | 中国航空动力机械研究所 | Aero-engine dynamic test system, frequency-voltage transformation circuit and method |
| CN106405231A (en) * | 2016-08-31 | 2017-02-15 | 无锡小天鹅股份有限公司 | Household electrical appliance and power source frequency detection method and apparatus therefor |
| CN107238755A (en) * | 2017-05-27 | 2017-10-10 | 何永平 | The resonant frequency measurement method and measuring system resonator of a kind of oscillator |
| CN112710897A (en) * | 2020-12-07 | 2021-04-27 | 广东电网有限责任公司韶关供电局 | Frequency measuring circuit |
| CN115173558A (en) * | 2022-07-15 | 2022-10-11 | 国网江苏省电力有限公司 | New forms of energy station yard on-line measuring system |
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