CN106093568A - A kind of novel low-cost high-precision digital frequency meter - Google Patents
A kind of novel low-cost high-precision digital frequency meter Download PDFInfo
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- CN106093568A CN106093568A CN201610629578.2A CN201610629578A CN106093568A CN 106093568 A CN106093568 A CN 106093568A CN 201610629578 A CN201610629578 A CN 201610629578A CN 106093568 A CN106093568 A CN 106093568A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
- G01R23/10—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage by converting frequency into a train of pulses, which are then counted, i.e. converting the signal into a square wave
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Abstract
The invention discloses a kind of novel low-cost high-precision digital frequency meter, it relates to digital frequency meter technical field.It is digital frequency meter based on FPGA, and front end signal input conditioning uses broadband amplifier AD8099 to be amplified small-signal, becomes size after high-speed comparator TLV3501 shaping, and waveform is suitable for the signal that FPGA directly processes；Between STM32 single-chip microcomputer and FPGA, the change according to sequential transmits control, state, data message, and CPU reads count value from FPGA, the setting of module is selected according to button, determine signal parameter type to be measured, then through further calculation process, output to OLED shows.Present invention have the beneficial effect that it is measured the method for frequency and uses equal precision measurement method, compare direct frequency measurement method and its precision of cycle test method is higher, measure wider, disclosure satisfy that the requirement of 1Hz to 100MHz frequency range, precision is also above 0.01%, and whole system real-time is good, motility is high, power consumption is little, low cost.
Description
Technical field
The present invention relates to digital frequency meter technical field, be specifically related to a kind of novel low-cost high-precision digital frequency meter.
Background technology
Cymometer is mainly made up of following three parts: signal shaping, signal parameter measurement, Single-chip Controlling and display.Its
In, signal parameter is measured can be subdivided into again the modules such as frequency/period measurement, time interval measurement, duty ratio measuring.
At present, in prior art, convectional signals amplifies Shaping Module, and one is to use discrete component to realize preposition amplification whole
Shape function, sends into phase inverter shaping after amplifying signal with two audions, find when measured signal amplitude is less by emulation,
Waveform quality obtained when frequency is higher is poor, and frequency cannot meet requirement completely more than output signal during 50MHz.Separately
Outward, this scheme needs to use in a large number discrete component, system design complexity, and the quantitatively regulation of debugging difficulty, especially gain is difficult to,
And poor stability, easy self-oscillation is also this circuit another drawback；Another kind of employing AD811 amplifying circuit in proportion
Amplifying small-signal, big signal directly inputs comparator, owing to the when of AD811 bandwidth product the least amplification high-frequency signal, decay is tight
Weight.
Meanwhile, also conventional frequency/period measurement module in prior art, one is time threshold measurement method, including directly
Frequency measurement and direct period measurement, Measuring Frequency Method is relatively big at the relatively low time error of frequency, and cycle test method is at the higher time error of frequency relatively
Greatly；Another kind is combined method, and this kind of scheme is implemented cumbersome, and certainty of measurement is difficult to mention the highest.
Finally, there is some deficiency following in existing Single-chip Controlling and display module, STC89C52 power consumption is higher, I/O mouth
Resource-constrained, processing speed is relatively slow, and liquid crystal 12864 exists that the life-span is short, screen size is less.
Summary of the invention
Present invention aims to defect and the deficiency of prior art, it is provided that a kind of simple in construction, reasonable in design, make
With convenient novel low-cost high-precision digital frequency meter, it is measured the method for frequency and uses equal precision measurement method, compares directly
Measuring Frequency Method and its precision of cycle test method are higher, measure wider, it is possible to meet the requirement of 1Hz to 100MHz frequency range, precision
Also above 0.01%, whole system real-time is good, motility is high, power consumption is little.
In order to solve the problem existing for background technology, the technical solution used in the present invention is: it includes signal shaping mould
Block, signal parameter measurement module, Single-chip Controlling and display module；Described signal parameter measurement module can be subdivided into again frequency
Rate/period measurement, time interval measurement, duty ratio measuring module.
Described signal shaping module uses AD8099 amplifying circuit in proportion, hysteresis comparator, input and output impedance matching,
The output signal clutter of this amplifying circuit is more, and the signal output waveform of amplifier is relatively thick, suitably regulates hysteresis comparator
Threshold voltage can the effectively clutter reduction impact on rear class comparator, when such input signal is square wave signal frequency and
The scope of virtual value is the most relatively wide, and input signal is for also meeting requirement time sinusoidal wave.
Described frequency/period measurement module uses equal precision measurement method, and two groups of enumerators are in identical time threshold
Counting, effective when signal strobe and measured signal rising edge starts counting up, when the trailing edge of gate thresholding arrives when arriving simultaneously
Coming, only when an end cycle of measured signal, two groups of enumerators just stop counting.
Described Single-chip Controlling and display module use STM32 single-chip microcomputer, 32 Cortex-M3CPU, and display module uses
OLED。
Front end signal input modulate circuit uses broadband amplifier AD8099 to be amplified small-signal, through high ratio
Become size after relatively device TLV3501 shaping, waveform is suitable for the signal that FPGA directly processes；Between STM32 single-chip microcomputer and FPGA
Transmitting controlled state, data message according to the change of sequential, CPU reads count value from FPGA, selects setting of module according to button
Fixed, determine signal parameter type to be measured, including frequency/period, time interval, dutycycle etc., then through further computing
Processing, output to OLED shows.
After using said structure, present invention have the beneficial effect that it is measured the method for frequency and uses equal precision measurement method, compare
Direct frequency measurement method and its precision of cycle test method are higher, measure wider, it is possible to meet the requirement of 1Hz to 100MHz frequency range,
Precision is also above 0.01%, and whole system real-time is good, motility is high, power consumption is little.
Accompanying drawing explanation
Fig. 1 is the system the general frame of the present invention；
Fig. 2 is the signal shaping block diagram of the present invention；
Fig. 3 is the signal measurement block diagram of the present invention；
Fig. 4 is Single-chip Controlling and the block diagram of the present invention.
Detailed description of the invention
Below in conjunction with the accompanying drawings, the present invention is further illustrated.
In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with accompanying drawing and be embodied as
Mode, is further elaborated to the present invention.Should be appreciated that detailed description of the invention described herein is only in order to explain this
Invention, is not intended to limit the present invention.
As Figure 1-Figure 4, this detailed description of the invention adopts the following technical scheme that it includes signal shaping module, signal
Parameters measurement module, Single-chip Controlling and display module；Described signal parameter measurement module can be subdivided into again frequency/period and survey
Amount, time interval measurement, duty ratio measuring module.
Described signal shaping module uses AD8099 amplifying circuit in proportion, hysteresis comparator, input and output impedance matching,
The output signal clutter of this amplifying circuit is more, and the signal output waveform of amplifier is relatively thick, suitably regulates hysteresis comparator
Threshold voltage can the effectively clutter reduction impact on rear class comparator, when such input signal is square wave signal frequency and
The scope of virtual value is the most relatively wide, and input signal is for also meeting requirement time sinusoidal wave.
Described frequency/period measurement module uses equal precision measurement method, and two groups of enumerators are in identical time threshold
Counting, effective when signal strobe and measured signal rising edge starts counting up, when the trailing edge of gate thresholding arrives when arriving simultaneously
Coming, only when an end cycle of measured signal, two groups of enumerators just stop counting.This overcome the arteries and veins of measured signal
Cycle of rushing incomplete problem, its error is only produced by standard-frequency signal, unrelated with the frequency of signal to be measured, maximum error
For positive negative one the standard frequency cycle, and standard signal uses 10MHz, and corresponding precision reaches 10-7, it is fully able to reach to want
Refinement degree.
Described Single-chip Controlling and display module use STM32 single-chip microcomputer, and 32 Cortex-M3CPU, it has low-power consumption
Pattern, processing speed is very fast, and I/O mouth is more, can conveniently realize the communication with FPGA and peripheral hardware；Display module uses OLED, its
Thickness, weight will be better than LED, and angular field of view is big, and luminous efficiency is high, and energy consumption is low, meanwhile, LED compare OLED and
The shortcoming colored purity that speech there is also is not, the life-span is shorter, screen size is less.
Signal frequency/period measurement: no matter measured signal is sinusoidal wave or square wave, and all becoming after shaping circuit can
The square wave directly processed for FPGA, uses the equal precision measurement method mentioned in demonstration, can obtain 1～100MHz letter of requirement
Number frequency/period, select 10MHz square wave as standard signal, certainty of measurement can be made to be greatly improved.
Same frequency square wave time interval measurement: enter the same frequency square-wave signal of FPGA through process, when its frequency is relatively low,
Two-way with frequency and is existed the square wave of time interval carries out XOR, obtains a square wave.In order to improve certainty of measurement, can
Rectangle wave height level and low duration in the relatively cycle, so that persistent period length is carried out timing acquired results be
Standard, then homogenous frequency signal time interval is the difference in count value correspondence time or cycle and corresponding time；If but signal frequency is the highest
Continue to use this scheme, when especially square wave dutycycle is close to 50%, owing in interval time, reference signal counts number very
Few, and counting produce ± 1 error is objective reality, so wanting to reach permissible accuracy must improve constantly standard signal
Frequency.
One of square wave requirement as reference signal is stable and waveform is regular, and meanwhile frequency is the highest better.By
The square wave highest frequency produced in FPGA is 400MHz, it is considered to the situation that measurement error is maximum, i.e. square wave dutycycle is 50%
Time, it is desirable to reach the accuracy of 1%, then within one cycle of square wave, the number of reference signal now should draw not less than 200
The peak frequency of square wave is 2MHz, and correspondingly, the peak frequency of surveyed same frequency square wave is 1MHz, say, that when tested
When the frequency of signal is less than 1MHz, use such scheme can meet required precision completely.
When the frequency of measured signal is more than 1MHz, in order to ensure accuracy of measurement, can be to XOR gained square wave 1000
Frequency dividing, after frequency dividing, in one cycle of gained, the part of high level is as gate-control signal, with two enumerators respectively to gate-control signal
High level and low level in the square wave comprised in the case of You Xiao, the individual counting number of corresponding reference square wave, with persistent period length
It is as the criterion the calculating time.Owing to existing in each square wave cycle inside counting number ± error of 1, in extreme circumstances, amount to
Several several errors are ± 1000, now certainty of measurement and not divide be identical, but occur that the probability of this situation is minimum, and work as
The each cycle count of square wave produce ± 1 error is able to part on the contrary when cancelling out each other due to symbol, certainty of measurement
Improve to corresponding, such as, if grand total number error is 200, then the certainty of measurement after frequency dividing that is 5 times do not divide situation,
It should be noted that the probability that error is 200 is 1000 much larger than error.
Improve instrumental sensitivity measure: use equal precision measurement method, during counting originally measured signal number ± 1 error
On the basis of signal ± 1 error；Preposition amplification and rectification circuit amplifier two ends have all added coupling electric capacity, eliminate over the whole system as far as possible
The noise jamming that the factor such as power supply and environment causes；Circuit uses pcb board, and chip mostly is paster encapsulation, when reducing cabling
The interference introduced；Select the comparator of function admirable, amplifier chip etc., reduce the error that non-artificial factor causes；Introduce tested
During signal, use coaxial cable and BNC connector, reduce signal attenuation.
Present invention digital frequency meter based on FPGA, utilizes the design of Verilog hardware description language to achieve in cymometer
Portion's functional module, completion logic emulation on software platform Quartus.Front end signal input conditioning uses broadband amplifier
Small-signal is amplified by AD8099, becomes size, that waveform is suitable for FPGA is straight after high-speed comparator TLV3501 shaping
Connect the signal of process；Between STM32 single-chip microcomputer and FPGA according to sequential change transmit controlled state, data message, CPU from
FPGA reads count value, according to button select module setting, determine signal parameter type to be measured, including frequency/period,
Time interval, dutycycle etc., then through further calculation process, output to OLED shows.
This detailed description of the invention is measured the method for frequency and is used equal precision measurement method, compare direct frequency measurement method and cycle test method its
Precision is higher, measures wider, it is possible to meet the requirement of 1Hz to 100MHz frequency range, and precision is also above 0.01%, whole
System real time is good, motility is high, power consumption is little, low cost.
The above, only in order to technical scheme to be described and unrestricted, those of ordinary skill in the art are to this
Other amendment or equivalent that bright technical scheme is made, without departing from the spirit and scope of technical solution of the present invention,
All should contain in the middle of scope of the presently claimed invention.
Claims (2)
1. a novel low-cost high-precision digital frequency meter, it is characterised in that include that signal shaping module, signal parameter are measured
Module, Single-chip Controlling and display module；Described signal parameter measurement module can be subdivided into again frequency/period measurement, time
Interval measurement, duty ratio measuring module；Described signal shaping module use AD8099 amplifying circuit in proportion, hysteresis comparator,
Input and output impedance matching；Described frequency/period measurement module uses equal precision measurement method, and two groups of enumerators are when identical
Between count in thresholding, when signal strobe effectively and starts counting up, when gate thresholding time the rising edge of measured signal arrives simultaneously
Trailing edge arrives, and only when an end cycle of measured signal, two groups of enumerators just stop counting；Described Single-chip Controlling
And display module uses STM32 single-chip microcomputer, 32 Cortex-M3CPU, display module uses OLED.
A kind of novel low-cost high-precision digital frequency meter the most according to claim 1, it is characterised in that front end signal is defeated
Entering conditioning uses broadband amplifier AD8099 to be amplified small-signal, becomes after high-speed comparator TLV3501 shaping
Size, waveform are suitable for the signal that FPGA directly processes；Transmit according to the change of sequential between STM32 single-chip microcomputer and FPGA and control
State, data message, CPU reads count value from FPGA, selects the setting of module according to button, determines signal parameter to be measured
Type, including frequency/period, time interval, dutycycle etc., then through further calculation process, output to OLED shows.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201610629578.2A CN106093568A (en) | 2016-08-03 | 2016-08-03 | A kind of novel low-cost high-precision digital frequency meter |
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| CN201610629578.2A CN106093568A (en) | 2016-08-03 | 2016-08-03 | A kind of novel low-cost high-precision digital frequency meter |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106932640A (en) * | 2017-04-28 | 2017-07-07 | 金陵科技学院 | Pulse signal measurement method of parameters and system based on FPGA |
| CN109116107A (en) * | 2018-08-21 | 2019-01-01 | 山东中创软件商用中间件股份有限公司 | A kind of digital frequency meter |
| CN110068730A (en) * | 2019-05-07 | 2019-07-30 | 中国科学院电子学研究所 | Two-band frequency spectrum data acquisition method and device |
| CN110687773A (en) * | 2019-09-25 | 2020-01-14 | 武汉船舶通信研究所（中国船舶重工集团公司第七二二研究所） | Method, device and system for measuring time service precision of time unification system |
| CN111175573A (en) * | 2020-02-14 | 2020-05-19 | 深圳市科信通信技术股份有限公司 | Method, device, equipment and medium for detecting alternating voltage frequency |
| CN112595952A (en) * | 2020-11-20 | 2021-04-02 | 中国电子科技集团公司第五十八研究所 | Method for improving measurement precision of period parameters |
| CN112730979A (en) * | 2020-12-24 | 2021-04-30 | 太原航空仪表有限公司 | STM 32-based equal-precision frequency measurement method |
-
2016
- 2016-08-03 CN CN201610629578.2A patent/CN106093568A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106932640A (en) * | 2017-04-28 | 2017-07-07 | 金陵科技学院 | Pulse signal measurement method of parameters and system based on FPGA |
| CN109116107A (en) * | 2018-08-21 | 2019-01-01 | 山东中创软件商用中间件股份有限公司 | A kind of digital frequency meter |
| CN110068730A (en) * | 2019-05-07 | 2019-07-30 | 中国科学院电子学研究所 | Two-band frequency spectrum data acquisition method and device |
| CN110068730B (en) * | 2019-05-07 | 2020-08-07 | 中国科学院电子学研究所 | Dual-band frequency spectrum data acquisition method and device |
| CN110687773A (en) * | 2019-09-25 | 2020-01-14 | 武汉船舶通信研究所（中国船舶重工集团公司第七二二研究所） | Method, device and system for measuring time service precision of time unification system |
| CN110687773B (en) * | 2019-09-25 | 2021-08-06 | 武汉船舶通信研究所（中国船舶重工集团公司第七二二研究所） | Method, device and system for measuring time service precision of time unification system |
| CN111175573A (en) * | 2020-02-14 | 2020-05-19 | 深圳市科信通信技术股份有限公司 | Method, device, equipment and medium for detecting alternating voltage frequency |
| CN112595952A (en) * | 2020-11-20 | 2021-04-02 | 中国电子科技集团公司第五十八研究所 | Method for improving measurement precision of period parameters |
| CN112730979A (en) * | 2020-12-24 | 2021-04-30 | 太原航空仪表有限公司 | STM 32-based equal-precision frequency measurement method |
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