CN1012704B - Compensatory technique and device of series interference in dual-channel ratio recorder - Google Patents

Abstract

The present invention relates to a signal processing method and apparatus, which is adopted for overcoming errors generated due to crosstalk between two paths of electrical signals S-[1], S-[2] for obtaining the ratio R=I-[2]/I-[1] of the lighting intensity I-[1], I-[2] of dual light paths in the field of electricity, wherein the crosstalk between the two paths of electrical signals S-[1], S-[2] is caused by the inertia of a shared detector. The present invention is characterized in that the following units and adjustment states are set in the apparatus: a, a subtracter is arranged in front of a divider for respectively subtracting crosstalk quantities KS-[2], KS-[1] from the electrical signals S-[1], S-[2]; b, a multiplier is arranged for the respective calculation of *K to the electrical signals S-[1], S-[2]; the product is sent to the subtracter, and a K value is set through zero adjustment operation; c, a phase modulation timer is arranged for optimizing the adjustment and the control of the sampling phases of the electrical signals S-[1], S-[2] by using a light intensity sampling phase as a reference.

Description

Compensatory technique and device of series interference in dual-channel ratio recorder

The present invention is the relative ratios that the nationality non-electric quantity electrometric method obtains two passage dynamic physical amounts in the electricity field, and need overcome crosstalking and the real-time signal-processing method that ratio error adopted and the device that produce between the two path signal that the inertia of shared detector causes.

Conversion coefficient unanimity when two shared detectors of passage can guarantee that non-electric physical quantity is converted to electric weight.Because physical quantity is dynamic, they must alternately be sampled rapidly by modulator and deliver to detector, and detector becomes electric signal with them, before calculating ratio, must recover to become two passages through detuner again.Because detector has inertia, when the first passage physical quantity will be extended to detuner for the influence of detector to change second channel over to, do not disappear immediately but decay gradually; Vice versa.So, merely do not represent original two-way physical quantity separately through the two path signal that detuner resolves into, as getting the ratio of two path signal simply, ratio as the two-way physical quantity, then will comprise very big error, this phenomenon be called between two passages " crosstalking " (CROSS-TALK).

A typical example is the double light path infrared spectrophotometer, and it is used for the transmitance of working sample, i.e. the ratio of the light intensity of sample light path and reference path light intensity.Do not obtain at cross-interference issue before the solution of electricity field, this quasi-instrument can only adopt the bulk of optical feedback principle to avoid the error of crosstalking, but optical method has processing difficulties and other inherent defect.Beckman company proposed the electrical method (United States Patent (USP) 3,242,797) that a kind of solution is crosstalked in 1966.But in fact this method is not applied aborning.PERKIN ELMER company proposed the another kind of electrical method (BrP 1,538,450) (United States Patent (USP) 4,132,481) of crosstalking that solves in 1979.Its technological approaches is certain suitable sampling delay timing of finding restituted signal by debugging repeatedly, two-way is crosstalked be compensated, but its adjustment method and circuit structure is very complicated.Technological approaches of the present invention then is straightforward signals collecting and parameter setting, and it is very simple and accurate to make deduction crosstalk.

As with light intensity represents physical amount, the electric signal S after the demodulation ₁And S ₂Correspond respectively to the light intensity I of reference path and sample light path ₁And I ₂, before carrying out the ratio computing, should deduct crosstalking respectively earlier from another road.Amount of crosstalk to one tunnel should be proportional to the size of the signal on another road; The scale-up factor K that crosstalks here should be identical to two-way.In other words: S ₁Crosstalking of producing enters S ₂In amount be KS ₁, and S ₂Crosstalking of producing enters S ₁In amount be KS ₂That is to say (S ₂-KS ₁) to (S ₁-KS ₂) ratio should represent I ₂To I ₁Accurate ratio.This is the basic functional principle of the application's case technology.It has obtained proof theoretical and experiment.Amount of crosstalk KS ₁And KS ₂Be to electric signal S by multiplier ₁And S ₂Carry out that multiplying obtains.Because of 0＜K＜1, so just can play the effect of multiplier with a potentiometer.Potentiometer should be adjustable, so that set multiplier K.

Crosstalk coefficient K can be expressed with certain functional form by structural parameters relevant in the measurement mechanism, but practical in force establishing method is the adjusting zero method that the present invention adopts.With blocking the sample light path fully by plate, promptly make I during zeroing ₂=0, the rate value R of measurement mechanism output at this moment should equal zero, and as not, then adjusts the K value in the multiplier, till R=0.Molecule (S in this expression ratio computing ₂-KS ₁) be transferred to and equalled zero, just K is in correct setting value.

Modulator merges into one to two-way, detuner then is decomposed into two to one the tunnel, and the both does periodic motion, does not require that in this case technology they are strict in time corresponding, but the time relationship that will make them is adjusted to the phase differential of an optimization, with two path signal S ₁And S ₂Difference be criterion to the maximum.Because (S ₂-KS ₁) and (S ₁-KS ₂) all be S ₁And S ₂Poor, well-known, when drawing its difference and be a decimal as two big numbers are close, the contained error of then big number is reflected in the difference and will becomes big relative error.So arrange a phase-modulation timer in the present invention, be used for setting and optimize phase differential, the work phase place of detuner is controlled by this timer.

Exemplary embodiments of the present invention is a kind of ratio-recording double light path photometer as shown in the figure.In the accompanying drawing 1 is for be that photomodulator, 3 is rotor for stator, 14 for phase-modulation timer, 13 for selector switch, 12 for multiplier-adjustable potentiometer, 10 and 11 for multiplier unit, 9 for divider, 8 for subtracter, 7 for detuner, 6 for amplifier, 5 for detector, 4 by plate, 2.By measuring two-way light intensity I by alternating sampling ₁And I ₂Converting electric signal to samples and is decomposed into S ₁And S ₂To obtain rate value R=I ₂/ I ₁The photomodulator 2 that it generally has except this quasi-instrument, detector 3, amplifier 4, detuner 5 and carry out being provided with the following units relevant the unit such as divider 7 of ratio computing with feature of the present invention:

1. subtracter 6, are positioned at detuner 5 and decomposite electric signal S ₁And S ₂Afterwards, before the divider 7, in order to deduct restituted signal S respectively ₁, S ₂In from the amount of crosstalk KS on another road ₂And KS ₁

2. multiplier unit 8, are positioned at restituted signal S ₁And S ₂Shunt on, in order to respectively to S ₁And S ₂Carry out multiplying * K, promptly reappear amount of crosstalk KS ₁And KS ₂, this long-pending subtracter 6 of delivering to.As carry out operation of analog quantity.This unit is made up of multiplier main body and each selector switch 10,11 of front and back thereof.The simplest mode of multiplier is an adjustable potentiometer 9, and making multiplier is crosstalk coefficient K adjustable settings.Selector switch 10,11 is synchronoused working with detuner 5, makes multiplier alternately import one of two paths of signals, takes advantage of the subtracter that exports another road behind the K to, and purpose is with identical multiplier K when handling for two paths of signals.As carry out digital operation, then two-way is easy to accomplish the multiplier K with identical, thereby does not need to add the selection switch again.

The setting of multiplier K is operated with aforesaid zeroing and is realized, in the sample light path, be provided with for this reason one in order to block light path by plate 1.

3. phase-modulation timer 12, are positioned at after the photomodulator 2, before the detuner 5, are optimized adjustment and control in order to the sampling phase to electric signal.This unit is made up of a rotor 14 and a stator 13, and the former is the transmitter that rotates synchronously with photomodulator 2, sends light, electrical or magnetic signal; The latter maintains static, and only just angular displacement can be arranged when adjusting, and two sensors of 180 ° apart are housed.Rotor 14 whenever circles with photomodulator, and stator 13 produces two pulses, makes one week of detuner reciprocating action.Adjust the position, angle of stator, make to be connected across signaling point S ₁And S ₂Between the voltage table reading reach maximum, promptly finish the adjustment of above-mentioned phase differential optimum.

Claims (7)

1, the crosstalk compensation method during a kind of ratio that can be used for the double light path light intensity writes down is by measuring the two-way light intensity I by alternating sampling ₁And I ₂Converting electric signal to samples and is decomposed into S ₁And S ₂To obtain rate value R=I ₂/ I ₁, it is characterized in that adopting following signal processing method and measurement state to compensate crosstalking between the two path signal:

(a) be decomposed into S at electric signal ₁And S ₂Afterwards, carry out before the division arithmetic, have the subtraction unit to carry out subtraction respectively with the amount of crosstalk KS of deduction from another road ₂And KS ₁

(b) with electric signal S ₁And S ₂Draw along separate routes, have the multiplying unit to carry out multiplying * K respectively, gained long-pending in the above-mentioned subtraction as the usefulness of subtrahend, multiplier K is set by the zeroing operation, its zeroing method of operating is: at light intensity I ₂When being zero, the value of adjusting multiplier K is till equal zero ratio calculated value R;

(c) the electric signal sampling is decomposed into S ₁And S ₂The time, the determining of its sampling phase with poor (S ₁-S ₂) being criterion to the maximum, the relative set phase place is regulated and control the unit.

2, the crosstalk compensation method in the ratio record according to claim 1, it is characterized in that * when K adopted operation of analog quantity, the multiplier K value by the zeroing operating and setting both had been used for computing KS ₁, also be directly used in computing KS ₂

3, the crosstalk compensation method in the ratio record according to claim 1 is characterized in that be benchmark the time phase with luminosity sampling, the phase place of electric signal sampling is done the phase shift adjustment, the S after decomposing ₁With S ₂Poor (S ₁-S ₂) reach till the maximum.

4, the crosstalk compensation devices during a kind of ratio that can be used for the double light path light intensity writes down comprises photomodulator, detector, amplifier, detuner and the divider that carries out the ratio computing, by measuring the two-way light intensity I through the photomodulator alternating sampling ₁And I ₂Convert electric signal to and be decomposed into S through the detuner sampling again ₁And S ₂To obtain rate value R=I ₂/ I ₁, it is characterized in that being provided with in the device the following units and state be set;

A. becoming S through detuner decomposition electric signal ₁And S ₂Afterwards, before the divider, subtracter is set, to deduct amount of crosstalk KS respectively from another road ₂And KS ₁;

B. at electric signal S ₁And S ₂Shunt in multiplier is set, with respectively to S ₁And S ₂Carry out multiplying * K, the long-pending above-mentioned subtracter of delivering to of gained, multiplier K are set on the set adjustable parameter element in multiplier, have during setting by plate to make light intensity I ₂Be zero;

C., a phase-modulation timer is set after photomodulator, the sampling phase of electric signal is optimized adjusts and control.

5, the crosstalk compensation devices in the ratio record according to claim 4, when it is characterized in that multiplier adopts operation of analog quantity, be made up of an adjustable potentiometer and each selector switch of front and back thereof, potentiometer carries out multiplying * K, the sample-synchronous action of selector switch and electric signal makes S ₁And S ₂Alternately pass through multiplier.

6, according to the crosstalk compensation devices in claim 4 or the 5 described ratio records, it is characterized in that adjustable potentiometer in the multiplier, as the carrier of COEFFICIENT K, it is provided with state is to make light intensity I ₂When being zero, the value of K equals zero the output valve R of this ratio measure device.

7, the crosstalk compensation devices in the ratio record according to claim 4 is characterized in that phase-modulation timer is made of a pair of rotor and stator.Rotor and photomodulator rotate synchronously, and transmitter is housed, and stator is equipped with sensor, and rotor circles whenever then that the sensor of stator produces equally spaced two pulses, is used for controlling one week of electric signal alternating sampling.

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