CN201780332U

CN201780332U - Frequency meter

Info

Publication number: CN201780332U
Application number: CN201020152443XU
Authority: CN
Inventors: 冯筱林
Original assignee: Shanghai Polytechnic University
Current assignee: Shanghai Polytechnic University
Priority date: 2010-04-08
Filing date: 2010-04-08
Publication date: 2011-03-30
Anticipated expiration: 2020-04-08

Abstract

The utility model relates to a frequency meter, which comprises a core module, a pulse input circuit and a nixietube display circuit, wherein the pulse input circuit inputs signals to the core module through a circuit, and the nixietube display circuit is connected with the output end of the core module through circuits. Compared with the prior art, the utility model has the advantages that the frequency meter based on a field programmable gate array (FPGA) and provided by the utility model can greatly shorten the development period of a system, can reduce the fund investment; the frequency meter based on the FPGA and provided by the utility model can integrate the original circuit board level products into chip level products, so the power consumption can be reduced, the reliability can be improved, and at the same time, the on-line modification can be conveniently carried out on the frequency meter.

Description

A kind of frequency meter

Technical field

The utility model relates to a kind of frequency meter.

Background technology

In related application such as electronic engineering, resource exploration, instrument and meter, frequency meter is the requisite survey instruments of engineering technical personnel.Frequency measurement also is one of the most modal measurement in the electronic measurement technique.The measurement of many physical quantitys all relates to the measurement that maybe can be converted into frequency as the measurement of rotating speed, vibration frequency etc.At present, various multi-functional, high precision, high-frequency digital frequency meter are arranged on the market, but its shortcoming is expensive.

The appearance of field programmable gate array (FPGA, Field Programmable Gate Array) is the result of VLSI (very large scale integrated circuit) (VLSI) technology and computer-aided design (CAD) (CAD) technical development.FPGA device integrated level height, volume are little, have the function that realizes specialized application by user program, and its allows circuit designers based on computer platform, through design input, emulation, test and verification, up to reaching expected result.The FPGA device becomes the desirable device of development, is particularly suitable for the model machine exploitation and the small serial production of product, and therefore people also call programmable ASIC to FPGA sometimes.

In recent years, the FPGA market development is very rapid, and each big FPGA manufacturer constantly employs new technology and improves the capacity of FPGA device, strengthens the performance of software.Nowadays, the FPGA device is widely used in numerous areas such as communication, control automatically, information processing, and increasing Electronic Design personnel are using FPGA, and on top of the FPGA designing technique has been the basic demand to the electronic design engineering teacher.

The utility model content

The purpose of this utility model provides a kind of frequency meter, realizes based on FPGA, can finish the various functions of frequency meter, and realizes that cost is low, reliability is high, the reduction power consumption.

To achieve these goals, the utility model provides a kind of frequency meter, is characterized in, comprises nucleus module, pulse input circuit and charactron display circuit;

Above-mentioned pulse input circuit by circuit to the nucleus module input signal;

Described charactron display circuit is connected with the circuit of output terminal of nucleus module.

Above-mentioned frequency meter, wherein, nucleus module is a fpga chip.

Above-mentioned frequency meter, wherein, fpga chip comprises frequency counting module and scanning display module, and the two is integrated on the fpga chip.

Above-mentioned frequency meter, wherein, the frequency counting module comprises the time control module and the counting module of mutual data transmission.

Above-mentioned frequency meter, wherein, time control module can change gating time; Described counting module is counted the positive pulse of measured signal according to the length of gating time.

Above-mentioned frequency meter, it also comprises shaping circuit, and described shaping circuit is connected with the output terminal of pulse input circuit and the counting module circuit of nucleus module respectively.

Above-mentioned frequency meter, wherein, shaping circuit becomes the signal shaping of pulse input circuit input into the desired pulse signal of counting module.

The utility model compared with prior art, its advantage is: what the utility model provided can shorten lead time of system greatly based on the frequency meter of FPGA, reduces fund input; The frequency meter based on FPGA that the utility model provides can be integrated into the chip-scale product with original circuit board level product, thereby has reduced power consumption, has improved reliability; Simultaneously, can also carry out online modification to frequency meter easily.

Description of drawings

Fig. 1 is the structured flowchart of the frequency meter that provides of the utility model;

Fig. 2 is the working waveform figure of the frequency meter that provides of the utility model.

Embodiment

Below in conjunction with Fig. 1 and Fig. 2, describe preferred embodiment of the utility model in detail.

As shown in Figure 1, Fig. 1 is the structured flowchart of the frequency meter that provides of the utility model.

A kind of frequency meter comprises nucleus module 1, pulse input circuit 2, shaping circuit 3 and charactron display circuit 4.To nucleus module 1 input signal, charactron display circuit 4 is connected with the circuit of output terminal of nucleus module 1 pulse input circuit 2 by circuit.Shaping circuit is connected with the output terminal of pulse input circuit 2 and counting module 112 circuit of nucleus module respectively.

Nucleus module 1 is a fpga chip, and fpga chip is made up of two big functional modules: (1) frequency counting module 11, frequency counting module 11 comprise the time control module 111 and the counting module 112 of mutual data transmission.Time control module 111 can change gating time, and counting module 112 is counted the positive pulse of measured signal according to the length of gating time; (2) scanning display module 12 scans demonstration to the result who counts, thereby finishes the process of whole measured frequency.

Shaping circuit 3 is that the measured signal shaping is become the desired pulse signal of counter.Circuit form adopts the Schmidt trigger that is made of 555 timers.If measured signal is sinusoidal wave, the input shaper circuit is provided with analysis and is transient analysis, start-up circuit, and its input, output waveform are as shown in Figure 2.Be output as square wave as seen from the figure, the two frequency is identical, and the frequency that frequency meter records square wave is sinusoidal wave frequency.

Principle of work of the present utility model is: measured signal generates the counting module 112 that square wave (amplitude 0-5V) is input to the frequency counting module 11 in the nucleus module 1 through shaping, counting module 112 is according to the square wave rising edge counting that is provided, gate time is then by time control module 111 decisions, decide gear according to the residing scope of frequency, the result of counting is exported to scanning display module 12, by scanning, the size of display frequency on charactron display module 4.

Digital frequency meter is the directly decimally digital a kind of measurement mechanism that shows the measured signal frequency.It not only can measure the frequency of sine wave, square wave, triangular wave and spike pulse signal.But also the cycle that can measure them.Digital frequency meter also obtains widespread use in other physical quantitys of measurement such as aspects such as rotating speed, vibration frequency.

Frequency is exactly the number of times that cyclical signal changed in the unit interval (1s).If record the repetition change frequency N of this cyclical signal at certain time intervals in the T, then its frequency can be expressed as: f=N/T.

The effect of pulse shaping circuit is: measured signal is become pulse signal, and its repetition frequency equals tested frequency f x.The time reference signal generator provide standard time pulse signal, if its cycle be 1s.Then the output signal duration of gating circuit also equals 1s exactly.Gate circuit is controlled by the standard second signal, when second signal come then, gate is open-minded.The measured pulse signal is delivered to the count decoding display circuit by gate.Closing gate during second signal ended, counter stop counting, and the waveform of each point as shown in Figure 2.Because the umber of pulse N that gets of counter meter is the accumulative total in 1 second time, so be exactly the umber of pulse NHz that counts by measured frequency.

At present, three kinds of numerical frequency measuring methods commonly used: the direct method of measurement, period measurement method and integration measurement method (direct method of measurement+period measurement method).

1. the direct method of measurement is to measure the pulse number of measured signal in given gate time, and converting draws the frequency of measured signal.

2. the period measurement method is by measuring the pulse number of measured signal one-period time timing signal, conversing the frequency of measured signal then.

3. to establish actual gate time be τ to integration measurement method, and the measured signal periodicity is Nx, and then it converts then and draw the frequency of measured signal by measuring the time in several cycles of measured signal.

Although content of the present utility model has been done detailed introduction by above preferred embodiment, will be appreciated that above-mentioned description should not be considered to restriction of the present utility model.After those skilled in the art have read foregoing, for multiple modification of the present utility model with to substitute all will be conspicuous.Therefore, protection domain of the present utility model should be limited to the appended claims.

Claims

1. a frequency meter comprises nucleus module (1), pulse input circuit (2) and charactron display circuit (4), it is characterized in that;

Described pulse input circuit (2) by circuit to nucleus module (1) input signal;

Described charactron display circuit (4) is connected with the circuit of output terminal of nucleus module (1).

2. frequency meter as claimed in claim 1 is characterized in that, described nucleus module (1) is a fpga chip.

3. frequency meter as claimed in claim 2 is characterized in that, described fpga chip comprises frequency counting module (11) and scanning display module (12), and the two is integrated on the fpga chip.

4. frequency meter as claimed in claim 3 is characterized in that, described frequency counting module (11) comprises the time control module (111) and the counting module (112) of mutual data transmission.

5. frequency meter as claimed in claim 1 is characterized in that, also comprises shaping circuit (3), and described shaping circuit is connected with the output terminal of pulse input circuit (2) and counting module (112) circuit of nucleus module respectively.