CN102096056A - Method for automatically correcting sound card oscilloscope - Google Patents

Abstract

The invention provides a method for automatically correcting a sound card oscilloscope. The method comprises the following steps of: utilizing a sound card of a computer as a data acquisition card of a sound card oscilloscope, wherein a microphone socket of the sound card is used as a data acquisition input end; after the microphone volume of the sound card is changed, calculating the range vlc of the sound card oscilloscope under the current volume value of the microphone by the sound card oscilloscope according to a formula; and adjusting each scale of a displayed picture so as to correctly display the waveform value of an input acquired signal. The invention also comprises a simple calibration method and overcomes the defect of difficulty of correction of the traditional sound card oscilloscope.

Description

Automatically calibrate the method for Sound Card Oscillograph

[technical field]

The present invention relates to the virtual oscilloscope field.Particularly about a kind of method that can calibrate Sound Card Oscillograph automatically.

[background technology]

Continuous development along with computer technology and virtual instrument technique, virtual instrument becomes a developing direction of modern instrument gradually, its core concept is to utilize the powerful resource of computing machine to make the hard-wired technical softwareization of original needs, so that reduce system cost to greatest extent, the function of enhanced system and dirigibility.Present most of virtual instrument all is based on commercial data collecting card as hardware platform, but total system costs an arm and a leg, and some function may be also impracticable in some concrete application scenarios.Audio signal sample system-sound card as a standard configuration of multimedia computer, its digital information processing system comprises that the modulus dress changes its A/D and digital and analogue signals converter D/A, can realize the collection and the output of simulating signal, therefore the virtual instrument based on sound card has the advantage that cost is low, versatility good and dirigibility is high, and virtual oscilloscope, Virtual Multimeter and Virtual Frequency Spectrum Analyzer based on sound card have been arranged now.

But existing Sound Card Oscillograph otherwise do not have the calibration function, can only roughly check waveform; The condition of demarcating calibration is relatively harsher, such as signal generator that needs standard and oscillograph; Be exactly to demarcate after the calibration, after microphone volume changes, demarcate calibration again again.

[summary of the invention]

The object of the present invention is to provide the method for automatic calibration Sound Card Oscillograph, it can finish the difficult point problem of the demarcation calibration of sound card virtual oscilloscope in the past by shirtsleeve operation.

The technical solution adopted in the present invention is:

Utilize the data collecting card of the sound card of computer as Sound Card Oscillograph, the Microphone of described sound card is as the data acquisition input end;

After the microphone volume of described sound card changed, described Sound Card Oscillograph was according to formula

$V_{\mathrm{lc}}=\frac{\sqrt{2}{\mathrm{Vol}}_0{V}_{\mathrm{rms}}{N}_{\max }}{{\mathrm{VolN}}_0}$

Calculate the range V of described Sound Card Oscillograph under current microphone volume value _Lc, and adjust every lattice scale of display frame, with the waveform values of the acquired signal of correct demonstration input;

Wherein Vol is the current microphone volume value of representative, V _RmsThe voltage effective value of the standard signal that records when being the input standard signal, Vol ₀Microphone volume value when being the input standard signal, N ₀Be that the maximal value of the input signal data that described Sound Card Oscillograph collects during standard signal deducts the poor of numerical value gained that minimum value draws, N _MaxIt is the range of the sound card that adopts.

Further, the aforesaid standards signal is to be produced by the signal generator in the aforementioned computer.

Further, the signal generator in the aforementioned computer is to be produced by software.

Further, the aforesaid standards signal is the sine wave signal of fixed frequency.

Further, the standard signal of aforementioned input microphone jack is the standard signal that is produced by signal generation software in the aforementioned computer of the earphone jack of aforementioned computer sound card output.

Further, measuring aforementioned N ₀The time, be that the standard signal with the output of described earphone jack is input to microphone jack by tone frequency channel wire, the maximal value of the signal data of the described standard signal that collects by Sound Card Oscillograph deducts the poor of numerical value gained that minimum value draws.

Aforementioned V further, _RmsIt is the effective value of measuring the standard signal that the standard signal of described earphone jack output draws by the alternating voltage shelves of multimeter.

Further, described sound card adopts is 16 sound cards, its range N _MaxBe 65535.

Aforementioned Vol and aforementioned Vol further, ₀All be the data that obtain in real time automatically from aforementioned computer by Sound Card Oscillograph.

The present invention utilizes digital multimeter and virtual signal generator, has improved the shortcoming that is difficult to calibrate of traditional in the past sound card virtual oscilloscope by simple demarcation calibration steps.

[description of drawings]

In order to be illustrated more clearly in the technical scheme of the embodiment of the invention, the accompanying drawing of required use is done to introduce simply in will describing embodiment below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1, it shows the operate as normal schematic diagram of the sound card that adopts among the present invention.

Fig. 2, it shows the present invention's fundamental diagram of the sound card virtual oscilloscope of calibration automatically.

Fig. 3, it shows the hardware connection layout of timing signal among the present invention.

Fig. 4, it shows and demarcates the Calibration Method process flow diagram among the present invention.

Fig. 5, it shows the structural representation of microphone volume control circuit.

[embodiment]

Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described.Obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, the every other embodiment that those of ordinary skills are obtained under the situation that does not break away from the present invention's essence and spirit belongs to the scope that the present invention is open and protect.

Signals collecting is the prerequisite of signal analysis and processing in the engineering, usually adopt data collecting card to finish, data collecting card generally comprises multi-way switch, amplification and sampling maintenance, A/D conversion, Computer I/parts such as O interface, and performance is fairly perfect, but the price comparison costliness.And for PC, sound card almost is modal the configuration, even many mainboards are with regard to integrated sound card.The height of sound card, the branch of low grade mainly is to be on the playback effect of sound, such as to three-dimension stereo, surrounding effect, multichannel, complex tone, Doby, the support of hard wave table etc., but substantially all has signal filtering, amplify and the sampling maintenance, functions such as A/D and D/A conversion, these functions and data collecting card are suitable, sound card commonly used can be realized 16 of two-channels to sound signal, the data acquisition of high-fidelity, high sampling rate can reach 44.1kHz, have higher sample frequency and precision, for many scientific experiments and engineering survey, sound card all is sufficiently high to the quantified precision and the sampling rate of signal, can be used as data collecting card fully uses, when using sound card as data collecting card, what mainly pay close attention to is the recording result of sound card, promptly gather number of vias, sample frequency, sampling resolution, and the specification of input signal.

Sound card characteristic commonly used among the PC is:

Gather number of vias: sound card is supported single channel, two-way collection;

Sample frequency: the standard sample frequency of sound card support has: 8000,11025,22050,44100 (per seconds);

Sampling resolution: the sampling resolution of sound card support is generally 8,16.

Adopted the data acquisition that can realize 16 of two-channels, high-fidelity in one embodiment of the invention to sound signal, high sampling rate can reach the AC97 sound card of 44.1kHz as data collecting card, the display of PC is as display device, and constitutes virtual oscilloscope based on sound card in conjunction with software.The external interface of described sound card has: circuit input (Line-in), loudspeaker (SpeakerOut), microphone (Microphone), game port (GamePort).Line-in and Microphone all can be used as signal input port.Obviously, by sound card as the oscillograph of data collecting card design receptible signal excursion should adapt to the signal excursion of Line-in or microphone port.

See also shown in Figure 1ly, it shows the operate as normal schematic diagram of the sound card that adopts among the present invention.The sound card 10 that the present invention adopts comprises signal pre-process module 11, data input buffer district module 12, digital signal processing module 12, data output buffer module 14 and D/A waveform reconstruction module 15.After the analog acoustic signal of importing by Line-in interface or Microphone interface is through described signal pre-process module 11 and A/D conversion, become digital signal, send into data input buffer district module 12, digital signal processing module 12 is handled the data of data input block module 14 by the method for various digital signal processing then, finish the sound de-noising, audio is handled, functions such as sound is synthetic, at last the data of handling well are kept at 14 li of data output buffers, deliver to loudspeaker (SpeakerOut) output interface by D/A waveform reconstruction module 15 and finish sound playing, may also have the power amplifier chip to finish the power amplification function for different loudspeakers simultaneously.

See also shown in Figure 2ly, it shows the fundamental diagram of the sound card virtual oscilloscope that can calibrate automatically among the present invention.

The present invention has adopted sound card as data collecting card, the PC display is as display device, cooperate software to form the sound card virtual oscilloscope 20 that to calibrate automatically, it comprises data acquisition module 21, signal pre-process module 22, data input buffer district 23, digital signal processing module 24, data output buffer 25, automatic calibration module 26 and waveform display module 27, described data acquisition module comprises p-wire, microphone (MIC) interface on the sound card of microcomputer (PC) and circuit input (Line-in) interface, wherein microphone interface and circuit input interface can be as input interfaces, in the explanation below, all explain as input interface with microphone interface, when circuit input interface during as input interface, similar with it, be not repeated.The method for making of p-wire (in fact it is exactly the stereo audio line for an input, an output) is: stereo plug is outwarded winding, can see 3 binding posts, corresponding ground wire, L channel, R channel connect shielding layer grounding with three-core shielding line corresponding end respectively; Detect corresponding relation with multimeter, guarantee not short circuit.The three-core shielding line can connect fish folder, test pencil etc., so that measure.Microphone (MIC) interface on the other then sound card that is connected on microcomputer (PC) and circuit input (Line-in) interface, be the safety that guarantees to measure, should be appreciated that some parameters of sound card on the computer, as input range and output area (sound card be 1V AC); If will import more large-signal, should will import after the signal attenuation, otherwise can damage sound card.Described signal pre-process module 22 comprises the upward signal pre-process module of sound card of microcomputer (PC), mainly is that simulating signal is converted into digital signal, i.e. the A/D converter.In an embodiment of the present invention, it is with the sampling rate work of 44.1kHz.Described digital signal processing module 24 is to carry out data processing by the DSP Audio Processing chip in the sound card on the microcomputer (PC).Described data input buffer district 23 and data output buffer 25 all are the data buffers in the sound card on the microcomputer (PC).Described waveform display module 27 is the display devices that utilize on the microcomputer (PC).Described sound card virtual oscilloscope also comprises the virtual signal generator module.

After the simulating signal of importing by data acquisition module 21 is through described signal pre-process module 22 and A/D conversion, become digital signal, send into data input buffer district 23, digital signal processing module 24 is handled the data of data input block module 14 by the method for various digital signal processing then, finish filtering, function such as synthetic, at last the data of handling well are kept at 25 li of data output buffers, before the data that waveform display module 27 extracts 25 li of data output buffers are finished the waveform demonstration, automatically calibration module will check whether the scale of demarcating is correct, when incorrect, revise demonstration more at once.

Described automatic calibration need at first be demarcated, and promptly when using for the first time, oscillographic range and scale is done demarcation.The method of timing signal is varied, traditional method is that the signal generator of employing standard sends a standard signal and is input in the virtual oscilloscope and demarcates, in the present invention, employing be that the standard signal that virtual signal generator produces is demarcated, concrete scaling method is as follows:

Please continue with reference to figure 3, it shows the hardware connection layout of timing signal among the present invention.

The tone frequency channel wire that all is the 3.5mm plug with a two connects earphone output plughole and microphone jack (or Line-in jack).

Please continue with reference to figure 4, it shows and demarcates the Calibration Method process flow diagram among the present invention.This method step is:

Step 410 at first by the sine wave of a virtual signal generator fixed frequency of output (as: 1kHz), is exported by earphone jack,

Step 420 is input to the microphone input jack by tone frequency channel wire again.

At this moment step 430 can be seen collecting sine waveform on software oscillograph interface, regulates output volume, makes the waveform that collects that saturation distortion not take place.

Step 440 is extracted tone frequency channel wire then from the microphone input jack, with the magnitude of voltage of digital multimeter alternating voltage shelves test output, this value is exactly sinusoidal wave effective value V _Rms

Step 450 is inserted into the microphone input jack to tone frequency channel wire then again, simultaneously this V _RmsValue is input in the calibration procedure of software, clicks and sets button, can realize automatic calibration.

The characteristics of said method are to produce by virtual signal generator the sine wave of a fixed frequency, economize the limitation that needs standard signal generator when having omitted traditional scaling method, have used digital multimeter to obtain sinusoidal wave effective value V again _Rms, in conjunction with the known frequency in front, just can come oscillograph is demarcated by calculating all relevant parameters of acquisition waveform, for example pass through V _RmsCan calculate sinusoidal wave peak value V _Pp:

$V_{\mathrm{pp}}=\sqrt{2}\mathrm{Vrms}---1-1$

Other CALCULATION OF PARAMETERS are not repeated, but are to have solved the demarcation problem under the constant situation of microphone volume value like this, do not need to demarcate when changing for the microphone volume value again, also need automatic calibration.Described automatic calibrating principle is:

At first consider under the constant situation of microphone volume value, when to known amplitude V of microphone jack input _PpSine wave since this moment the numerical value of N that collects ₀(N ₀Be software collection to the maximal value of data of sine wave deduct the numerical value that minimum value draws) with the magnitude of voltage V of input signal _PpBe one to one, and be linear, therefore can determine the signal numerical value of N of gathering ₀With applied signal voltage value V _PpBetween scale-up factor K.When any input voltage V was measured in conversion, the measured value that shows on the software was N, then can determine the value V of input voltage according to formula 1-1:

$K=\frac{V_{\mathrm{pp}}}{N_0}=\frac{V}{N},V=\mathrm{KN}---1-2$

Because the range of 16 sound cards is that the resolution of sound card is 65535, the span of N maximum is 0～65535 in the promptly top formula, when N=65535, V is exactly the maximum voltage value of institute's energy measurement of described sound virtual oscilloscope, it is exactly the range of described virtual oscilloscope, know after the range, just can calculate the magnitude of voltage of every lattice representative on the oscillograph.So can be easy to obtain following result by 1-2:

$K=\frac{V_{\mathrm{pp}}}{N_0}=\frac{V_{\max }}{N_{\max }},$ N _max＝65535，V _max＝KN _max

1-3

V wherein _PpIt is the sinusoidal wave peak value that calculates by Vrms; N ₀Be software collection to the maximal value of data of sine wave deduct the numerical value that minimum value draws; N _MaxBe the range of sound card, 16 sound cards are 65535; V _MaxIt is the range of described sound card virtual oscilloscope under the constant situation of current microphone volume value.

Consider the situation that the microphone volume value changes then, because signal also will pass through the microphone volume control circuit by after the microphone jack input, can be with reference to figure 5, it shows the structural representation of microphone volume control circuit.Therefore the input signal numerical value that sound card collects for different volume values of identical size is different.After the microphone volume value changed, the K of Biao Dinging can change before, must demarcate again.In Fig. 5, the voltage of input is V, but by behind the volume control circuit, the virtual voltage that the sound card A/D converter receives is V _s, we introduce microphone volume number percent factor M, the volume maximal value Vol of described sound card at this _MaxAnd real-time volume value Vol.Obvious, following relationship is arranged:

$\frac{V_s}{V}=\frac{\mathrm{Vol}}{{\mathrm{Vol}}_{\max }}=M---1-4$

The voltage range of every sound card A/D converter institute energy measurement is fixed, and supposes that this fixing voltage range is V _Sm, be Vol at the volume value of timing signal ₀, promptly the microphone volume number percent factor is M ₀, then can access following result in conjunction with 1-3 and 1-4:

$V_{\mathrm{sm}}=M_0{V}_{\max }=\frac{{\mathrm{Vol}}_0{V}_{\max }}{{\mathrm{Vol}}_{\max }}=\frac{{\mathrm{Vol}}_0{\mathrm{KN}}_{\max }}{{\mathrm{Vol}}_{\max }}=\frac{{\mathrm{Vol}}_0{V}_{\mathrm{pp}}{N}_{\max }}{{\mathrm{Vol}}_{\max }{N}_0}=\frac{\sqrt{2}{\mathrm{Vol}}_0{V}_{\mathrm{rms}}{N}_{\max }}{{\mathrm{Vol}}_{\max }{N}_0}---1-5$

All data all are given datas in the above-mentioned formula 1-5, promptly can clearly know the range V of the A/D converter of the sound card that uses _Sm, when microphone volume changes, only need know real-time volume value Vol, just can obtain the range V of real-time described sound card virtual oscilloscope by formula 1-4 and formula 1-5 _Lc:

$V_{\mathrm{lc}}=\frac{V_{\mathrm{sm}}}{M}=\frac{V_{\mathrm{sm}}{\mathrm{Vol}}_{\max }}{\mathrm{Vol}}=\frac{\sqrt{2}{\mathrm{Vol}}_0{V}_{\mathrm{rms}}{N}_{\max }}{\mathrm{Vol}{N}_0}---1-6$

So the present invention utilizes virtual signal generator that the sine wave of a fixed frequency takes place when using by the first time, just can demarcate with a digital multimeter again described sound card virtual oscilloscope, utilize the formula in the 1-6 then, just can finish the function of automatic calibration, overcome the shortcoming that is difficult to calibrate of sound card virtual oscilloscope in the past.

The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. automatic method of calibration Sound Card Oscillograph is characterized in that this method comprises:

Utilize the data collecting card of the sound card of computer as Sound Card Oscillograph, the Microphone of described sound card is as the data acquisition input end;

After the microphone volume of described sound card changed, described Sound Card Oscillograph was according to formula

$V_{\mathrm{lc}}=\frac{\sqrt{2}{\mathrm{Vol}}_0{V}_{\mathrm{rms}}{N}_{\max }}{{\mathrm{VolN}}_0}$

Calculate the range V of described Sound Card Oscillograph under current microphone volume value _Lc, and adjust every lattice scale of display frame, with the waveform values of the acquired signal of correct demonstration input;

Wherein Vol is the current microphone volume value of representative, V _RmsThe voltage effective value of the standard signal that records when being the input standard signal, Vol ₀Microphone volume value when being the input standard signal, N ₀Be that the maximal value of the input signal data that described Sound Card Oscillograph collects during standard signal deducts the poor of numerical value gained that minimum value draws, N _MaxIt is the range of the sound card that adopts.

2. the method for automatic calibration Sound Card Oscillograph according to claim 1 is characterized in that: the aforesaid standards signal is to be produced by the signal generator in the aforementioned computer.

3. the method for automatic calibration Sound Card Oscillograph as claimed in claim 2 is characterized in that: the signal generator in the aforementioned computer is to be produced by software.

4. the method for automatic calibration Sound Card Oscillograph according to claim 2 is characterized in that: the aforesaid standards signal is the sine wave signal of fixed frequency.

5. the method for automatic calibration Sound Card Oscillograph according to claim 2 is characterized in that: the standard signal of aforementioned input microphone jack is the standard signal that is produced by signal generation software in the aforementioned computer of the earphone jack output of aforementioned computer sound card.

6. the method for automatic calibration Sound Card Oscillograph according to claim 5 is characterized in that: measuring aforementioned N ₀The time, be that the standard signal with the output of described earphone jack is input to microphone jack by tone frequency channel wire, the maximal value of the signal data of the described standard signal that collects by Sound Card Oscillograph deducts the poor of numerical value gained that minimum value draws.

7. the method for automatic calibration Sound Card Oscillograph according to claim 5 is characterized in that, aforementioned V _RmsIt is the effective value of measuring the standard signal that the standard signal of described earphone jack output draws by the alternating voltage shelves of multimeter.

8. according to the method for the described automatic calibration Sound Card Oscillograph of each claim item of claim 1-7, it is characterized in that what described sound card adopted is 16 sound cards, its range N _MaxBe 65535.

9. according to the method for the described automatic calibration Sound Card Oscillograph of each claim item of claim 1-7, it is characterized in that aforementioned Vol and aforementioned Vol ₀All be the data that obtain in real time automatically from aforementioned computer by Sound Card Oscillograph.

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