CN1280416A

CN1280416A - Feedback signal amplifying treating method

Info

Publication number: CN1280416A
Application number: CN 99113868
Authority: CN
Inventors: 李斌; 沈天飞
Original assignee: University of Shanghai for Science and Technology
Current assignee: Shanghai University; University of Shanghai for Science and Technology
Priority date: 1999-07-12
Filing date: 1999-07-12
Publication date: 2001-01-17
Anticipated expiration: 2019-07-12
Also published as: CN1167186C

Abstract

The feedback signal amplifying treatment method in the modulation of low frequency positive and negative square wave is suitable for amplifying treatment and digitalizing measurement of weak pulsed signal. The input signal is treated through three processes including the first process of high gain dynamically feedback control, the second process of translation of input signal in feedabck holding value and high gain amplification, and the third process of sample and subtraction of the amplified signal under the positive and negative modulation. The first and the second processes eliminate zero drift of signal dynamically and amplify the signal linearly in high gain and the third process eliminates industry frequency interference to signal dynamically and performs digital measurement.

Description

Feedback signal amplifying treating method

The present invention relates to a kind of feedback signal amplifying treating method, be specifically related to a kind of signal amplification treatment method under the positive and negative square wave modulation of low frequency.

Still there is not sort signal processing and amplifying method at present both at home and abroad.Signal amplification treatment method under the positive and negative square wave modulation of low frequency is that the change feed signals of transducer is disturbed by power frequency easily, disturbs for eliminating power frequency, and the employing cycle is that the positive and negative square wave of power frequency period even-multiple is modulated the signal transmitting of transducer.Like this, when the signal to transducer carries out processing and amplifying, the modulated process of corresponding positive and negative square wave, having following elimination power frequency disturbs and the digitized measurement operation: the sampled value with signal averaging under the positive square wave modulation deducts the negative square wave modulation sampled value of signal averaging down, and operation result can obtain a signal measurements of having eliminated the power frequency disturbing factor.But the actual signal that a lot of transducers changes are sent is not only very faint but also internal resistance is very high, tends to be superimposed with serious null offset and disturb in actual signal and processing procedure.As in the Detection of Weak Signals of ionic current scaling method (application for a patent for invention number 96116398.4) and fluid Hall potential method of measurement (application for a patent for invention number 96116387.6) etc., the order of magnitude that the null offset interference value will reach true signal value doubly.Therefore, in the actual signal of null offset interference that superposeed, can't actual signal wherein directly be amplified.Obviously, when actual signal can not get fully amplifying, can't eliminate power frequency to signal effectively and disturb and the digitized measurement operation.Usually be to adopt the isolated DC method to the processing and amplifying method that has null offset to disturb in the signal.Be typically mode, promptly provide processing and amplifying signal by AC coupled with traditional isolated DCs such as electric capacity.Because the mode of isolated DC makes actual signal produce distortion easily, and some null offset with slow variation is disturbed and is difficult to eliminate fully with the isolated DC method.Therefore, adopt the isolated DC method that actual signal is realized guaranteeing that linear amplification can bring difficulty.

The objective of the invention is to provide a kind of improved signal amplification treatment method under the positive and negative square wave modulation of low frequency, it not only can dynamically be eliminated null offset and disturb, and can realize faint actual signal is carried out high-gain ground linear amplification, disturb and the digitized measurement operation thereby can eliminate power frequency to signal effectively.

The objective of the invention is to realize in the following manner: in modulation period, it has taked three processing and amplifying processes to input signal at the positive and negative square wave of each low frequency.The one, just or the negatively-modulated section of beginning, input signal to be amplified by the high-gain that set-point carries out under the dynamical feedback, dynamical feedback is controlled dynamically at set-point the output after high-gain is amplified; The 2nd, just or under the negatively-modulated, the previous moment that sample to the signal after processing and amplifying, the dynamical feedback value is maintained, make fixedly retention value of one of later input signal elder generation translation, amplify back output by high-gain again; The 3rd, on having finished after two the processing and amplifying process, signal that will be after processing and amplifying by just with two kinds of situations of negatively-modulated, sample respectively and do to subtract each other processing.These three processing and amplifying processes have been eliminated null offset with making signal dynamics and have been disturbed and obtained high-gain ground linear amplification.Wherein, the 3rd processing and amplifying process has been finished simultaneously under the positive and negative square wave modulation of low frequency the elimination power frequency of signal has been disturbed and the digitized measurement operation.Owing to be to make full use of the positive and negative square wave modulation of the low frequency characteristics of signal processing down, with feedback controling mode signal is carried out processing and amplifying at signal in modulation period, dynamically eliminated the null offset interference, so realize easily the high-gain linear amplification of small-signal and the stability of inhibit signal processing and amplifying process, reach easily the high-precision digital of small-signal is measured.Simultaneously, whole feedback signal amplifying treating method has kept the signal response speed of the positive and negative square wave modulation system of low frequency itself.Therefore, the present invention is particularly suitable for faint and have the signal of pulsation to carry out processing and amplifying to some.

Specific implementation method of the present invention is provided by following embodiment and accompanying drawing thereof.

Fig. 1 is the fundamental diagram of the feedback signal amplifying treating method of proposition according to the present invention.Fig. 2 is the sequential relationship of control signal among Fig. 1.

Describe in detail according to the operation principle details of the present invention's proposition and the situation of signal processing and amplifying process according to Fig. 1 and Fig. 2 below.

Among Fig. 1, (1) representative has and becomes the transducer send coefficient C, it under the positive and negative square wave modulation of low frequency k0, the k0 under the corresponding modulation period just with the condition of forsaking one's love, if there is not any interference, can think transducer with tested measurement x0 become respectively send into: (+C) * x0 and (C) * the x0 two states.Signal x1 among Fig. 1 can be regarded as the real output signal of transducer under various disturbing factors.(2) represent impedance transducer, it may be that the signal x1 of high impedance is converted to low-impedance signal x2.(3) represent the amplifier that gain K is arranged of difference input, it is with the gain amplification of K of the difference of signal x2 and f1, output signal x3.(4) represent fixed value controller, it with s0 as set-point, with x3 as controlled variable, with f2 as control output valve.(5) represent sampling holder, it has two kind two to make mode by the sequential of Fig. 2: the one, when a k0 cycle just or negative beginning section, make the output f1 of sampling holder (5) dynamically equal to import f2 at control signal k1 during for high level, making (3), (4) and (5) three parts form a set-point like this is that s0, controlled volume are that x3, dynamical feedback amount are the K gain dynamical feedback fixed value controller of f2, and signal x3 dynamically is controlled at set-point s0; The 2nd, k0 just or negative down, T before will sampling to the signal after processing and amplifying constantly, control signal k1 becomes low level from high level, sampling holder (5) is maintained current f2 (T), the output f1 that is sampling holder (5) is constantly equal to f2 (T), at this moment (3) and (5) two parts with the translation of signal x2 elder generation a fixing retention value f2 (T), the amplification of the K that gains again obtains: the signal processing and amplifying result of x3=K * [x2-f2 (T)].(6) representing transfer ratio is the analog-digital converter of the voltage/frequency form of P, and it converts analog signal x3 to the frequency signal x4=P * x3 of digital form.Fig. 2 is the sequential of a k0 in the cycle.The remainder of Fig. 1 is to begin to operate after above-mentioned signal processing and amplifying.(7) among Fig. 1, (8) and (9) represent sampling switch respectively, counter and digital signal arithmetic unit, press just (bearing) and negative (just) two processes of k0, sampling switch (7) sum counter (8) carries out the double sampling operation to signal x4 respectively with counting mode when control signal k2 is high level, and with two count values respectively with the output of the digital signal form of x6, digital signal arithmetic unit (9) deducts count value under the negative process of k0 with the count value under the positive process of k0, operation result is with identical parallel moving of signal amount, the power frequency interference eliminated has obtained the detection limit x0 digitized measurement after by linear amplification x7 as a result.X7=2 * K * C * x0 * P is arranged.Fig. 1 (10) represent the digital signal display, and it shows digitized measurement x8 as a result.(11) represent control-signals generator, it exports three signals: the one, and the cycle is the positive and negative square wave modulation k0 of power frequency period even-multiple, it is modulated the signal transmitting process of transducer (1); The 2nd, control signal k1, it operates sampling holder (5); The 3rd, control signal k2, it operates sampling switch (7); Fig. 2 has represented the sequential relationship of three signals.

Claims

1. feedback signal amplifying treating method by amplifier (3), fixed value controller (4) and sampling holder (5) composition diagram 1 form, input signal x2 is pressed the sequential of Fig. 2, in the one-period of k0, carry out three signal processing and amplifying operations and method, it is characterized in that:

A. at k0 just or negative beginning section, the operation of k1 high level makes the output of sampling holder (5) directly transmit corresponding input f2; Corresponding processing method is: dynamically make f1=f2 and x3=K * (x2-f2)=s0;

B. will be to k0 (or negative) modulation signal x3 sampling T time before down just, k1 becomes the output f1=f2 (T) that low level operation makes sampling holder (5), and makes follow-up f1 value be constantly equal to f2 (T); Corresponding processing method is: make x3=K * [x2-f2 (T)];

C. after last two processing and amplifying operation, the processing and amplifying operation and the method for employing are: will just deduct under k0 negative (or just) sampled value to x3 to the sampled value of x3 under (or negative) at k0.