CN101820286A - Real-time signal reconstruction method for time-interleaved acquisition system - Google Patents

Abstract

The invention discloses a kind of live signal reconstructing methods of time-interleaved acquisition system, the sampling interval non-uniformity estimation by lowest mean square iteration, after obtaining the iteration of each channel k times

The adaptively sampling interval non-uniformity rn of acquisition time interleaved acquisition system, and then obtain the non-homogeneous introduced error component e [n] of system time-base, then live signal reconstruct is carried out, overcome current parallel sampling error calibration method is computationally intensive, real-time is not high, can not tracking error Parameters variation disadvantage, to meet the requirement of real-time of engineer application. The present invention is a kind of signal reconfiguring method for being more suitable for engineer application based on time-domain analysis, substantially reduce mathematical operation amount, good effect can be also obtained simultaneously, it is very useful on the engineer application of high speed time alternating sampling system design, there is good generalization.

Description

A kind of live signal reconstructing method of time-interleaved acquisition system

Technical field

The present invention relates to a kind of signal reconfiguring method, specifically, relate to a kind of live signal reconstructing method of time-interleaved acquisition system.

Background technology

Along with the continuous development of electronic information technology, the extremely strong dependence of real-time sampling speed has been become the bottleneck problem of modern time domain measurement instrument.And the research of modulus conversion technique (ADC) has limited the fast lifting of its technical indicator because of being subjected to the restriction of factors such as material, chip technology.

Under existence conditions, adopt parallel time alternating sampling structure to be still the unique channel of rapid raising system real-time sampling rate.The parallel time interleaved acquisition system adopt M sheet ADC with identical sample rate to the input analog signal alternating sampling one by one that walk abreast, recombinate the according to certain rules sampled value of each ADC of rear end makes the entire system sample rate reach M times of monolithic ADC sample rate.

Yet, the parallel time alternating sampling has been introduced new problem: owing to the inconsistency of the sampling clock delay error between M the passage, it is heterogeneous causing actual samples, with respect to carrying out unwanted phase modulated, seriously reduce the Spurious Free Dynamic Range and the actual signal to noise ratio of system to being sampled signal.

Signal reconstruction, utilize limited the resulting data value of sampling to carry out computing exactly according to certain rule, to determine the value of original unknown signaling on required each some ideal time, realize to the time base non-homogeneous signal reconstruct, thereby ensure the performance of time-interleaved acquisition system.

Time base error is with respect to the sampling period T of time-interleaved acquisition system _sIt is a very small time quantum.Traditional signal reconfiguring method need produce M small time quantum and be used to revise sampling clock in time-interleaved acquisition system, not only cause system too complicated for the circuit that the correction time base error increases, amount of calculation is big, designs loaded down with trivial detailsly, and systematic function is had very big influence.Simultaneously, because in the practical application, time base error can change along with the aging of ambient temperature and ADC device, conventional method need redesign to realize signal reconstruction, and efficient is low, is difficult to satisfy the real-time requirement of high speed acquisition system.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, provide a kind of.

For achieving the above object, the live signal reconstructing method of the time-interleaved acquisition system of the present invention may further comprise the steps:

(1), time-interleaved acquisition system is sampled to input signal x (t), if passage 0 is a reference channel, image data y[Mn with passage 0 output] deduct the image data y[M (n-1) in M sampling clock cycle of this passage output delay], obtain the sampled data difference e of passage 0 adjacent moment _0,0[n]:

e _0，0[n]＝y[Mn]-y[M(n-1)]

Then, with sampled data difference e _0,0[n] multiply by 1/M, obtains desirable sampled signal x (nT _s) single order derived function x ' (nT _s) and the sampling clock period T _sProduct T _sX ' (nT _s):

$T_s{x}^{\&prime;}\left(n{T}_s\right)\&ap;\frac{{\mathrm{<figure-callout\; id="0"\; label="e"\; filenames="H2009102164293E00021.png,H2009102164293E00022.png"\; state="\{\{state\}\}">e</figure-callout>}}_{\mathrm{0,0}}\left[n\right]}{M}$

In the formula, M is the port number of time-interleaved acquisition system, T _sBe the sampling clock cycle of time-interleaved acquisition system, n is a sampled point;

(2), with the image data y[Mn+m of passage m output] deduct the image data y[Mn of passage 0 output], obtain interchannel deviation signal e _{M, 0}[n]:

e _m，0[n]＝y[Mn+m]-y[Mn]

In the formula, m=1～(M-1);

(3), the desirable sampled signal x (nT that obtains according to step (1) _s) single order derived function x ' (nT _s) and the sampling clock period T _sProduct T _sX ' (nT _s) and the interchannel deviation signal e that obtains of step (2) _{M, 0}[n] obtains following error function

${\hat{e}}_m\left[\stackrel{\&CenterDot;}{n}\right]=e_{m,0}\left[n\right]-(1+{\hat{r}}_m)T_s{x}^{\&prime;}\left(\mathrm{Mn}{T}_s\right)$

In the formula,

For the sampling interval non-uniformity is estimated;

The sampling interval non-uniformity is estimated Carry out the lowest mean square iteration, iterations is k, makes error function

The mean square error minimum, obtain k the sampling interval non-uniformity after the iteration and estimate

(4), the sampling interval non-uniformity after k the iteration that obtains according to step (3) is estimated

And the desirable sampled signal x (nT that obtains of step (1) _s) single order derived function x ' (nT _s), obtain error component e _m[n]:

$e_m\left[n\right]\&ap;{\hat{r}}_m^k{T}_s{x}^{\&prime;}\left(n{T}_s\right)$

The error component e of each passage _m[n] constitutes time-interleaved acquisition system heterogenicity error component e[n];

(5), with the collection of time-interleaved acquisition system output y[n] deduct the heterogenicity error component e[n that step (4) obtains], obtain the desirable sampled signal x (nT of reconstruct _s):

x(nT _s)＝y[n]-e[n]。

Goal of the invention of the present invention is achieved in that

Adaptive control is a kind of constantly sensed system parameter or operating index in the course of the work, according to the variation of parameter or the variation of operating index, changes Control Parameter or control action, makes system run on optimum or approaches the FEEDBACK CONTROL of optimum operating state.In the present invention, self-adaptation control method is used for non-homogeneous signal reconstruction, by with the combined influence of error as feedback quantity, the control restructuring procedure, not only can realize the combination of estimation error and signal reconstruction, reduce the disposable complexity of obtaining error, and variation that can autotracking error.

For obtaining the influence that time base error is introduced, with the image data y[n of time-interleaved acquisition system] locate to do the Taylor expansion constantly at n:

y[n]＝x(nT _s+r _nT _s)≈x(nT _s)+(r _nT _s)x′(nT _s)+o(r _nT _s) (1)

Wherein, x () is an input signal; T _sBe the system sampling clock cycle; r _nBe the sampling interval non-uniformity; X ' () is the first derivative of signal; O () can ignore for the higher derivative remainder of signal Taylor exhibition formula.Can obtain desirable sampled signal x (nT by formula (1) _s) and non-homogeneous error component e[n]:

x(nT _s)＝y[n]-e[n] (2)

e[n]≈r _nT _sx′(nT _s) (3)

From formula (2) as can be seen, because the existence of time base deviation, non-homogeneous error component e[n is equivalent to superpose on ideal signal], its size depends on sampling interval non-uniformity r _n, sampling clock T _sAnd the single order derived function x ' (nT of input signal _s).

In the present invention, live signal reconstruct is exactly, and utilizes the statistical property of each channel sample data, and the instrument error function utilizes the lowest mean square iteration, and the sampling interval non-uniformity that obtains after k iteration of each passage is estimated

Thereby calculate non-homogeneous error component e[n], then, the image data y[n of time-interleaved acquisition system] in deduct non-homogeneous error component e[n], just obtain desirable sampled signal x (nT _s).In the present invention, the sampling interval non-uniformity after k iteration of each passage is estimated

Sampling interval non-uniformity r as whole time-interleaved acquisition system _nThereby, carry out live signal reconstruct according to formula (2), (3) and obtain desirable sampled signal x (nT _s).

The present invention is by the lowest mean square iteration, obtains the sampling interval non-uniformity estimation after k iteration of each passage

The sampling interval non-uniformity r of acquisition time interleaved acquisition system adaptively _nAnd then the non-homogeneous error component e[n that introduces of time base that obtains system], carry out live signal reconstruct then, the inferior position that overcomes that present parallel sampling error calibration method amount of calculation is big, real-time is not high, can't the tracking error parameter changes is to satisfy the real-time requirement that engineering is used.

The present invention is a kind of signal reconfiguring method of using based on the more suitable engineering of time domain analysis, reduced the mathematical operation amount greatly, simultaneously also can obtain good effect, use very practicality, have excellent popularization in the engineering of the time-interleaved sampling system design of high speed.

Description of drawings

Fig. 1 is the theory diagram of the live signal reconstructing method of the time-interleaved acquisition system of the present invention;

Fig. 2 is the time domain analysis figure of reconfiguration waveform before a parallel interleaved acquisition system is proofreaied and correct;

Fig. 3 is the spectrum analysis figure of reconfiguration waveform before the correction shown in Figure 2;

Fig. 4 is a mismatch error estimation procedure comparison diagram.

Embodiment

Below in conjunction with accompanying drawing the specific embodiment of the present invention is described, so that understand the present invention better.What need point out especially is that in the following description, when perhaps the detailed description that adopts known function and design can desalinate main contents of the present invention, these were described in here and will be left in the basket.

Embodiment

Fig. 1 is a kind of embodiment theory diagram that adopts the time-interleaved acquisition system of live signal reconstructing method of the present invention

As shown in Figure 1, time-interleaved acquisition system comprises M sheet ADC, i.e. ADC ₀..., ADC _M-1, each ADC input all links together, and all inserts same analog signal, i.e. the input signal x (t) of system.

Time-interleaved acquisition system is sampled to input signal x (t), output image data y[Mn] ..., y[Mn+m], these sampled datas promptly are combined into the collection output y[n of time-interleaved acquisition system at multiplexer by sampling time sequence among the MUX].

1), establish passage 0, in the present embodiment, i.e. ADC ₀Be reference channel, with ADC ₀The image data y[Mn of output] deduct the image data y[M (n-1) in M sampling clock cycle of this passage output delay], promptly go up a moment ADC ₀The image data of output obtains ADC ₀The sampled data difference e of adjacent moment _0,0[n]:

e _0，0[n]＝y[Mn]-y[M(n-1)]

In the present embodiment, in the said process, ADC ₀The image data of output adopts delay circuit to postpone, i.e. z ^-1, then, get negative value, obtain-y[M (n-1)], deliver in the adder and ADC ₀The image data y[Mn of output] carry out addition, promptly get ADC ₀The sampled data difference e of adjacent moment _0,0[n].

Then, again with sampled data difference e _0,0[n] sends into and multiply by 1/M in the multiplier, obtains desirable sampled signal x (nT _s) single order derived function x ' (nT _s) and the sampling clock period T _sProduct T _sX ' (nT _s):

$T_s{x}^{\&prime;}\left(n{T}_s\right)\&ap;\frac{{\mathrm{<figure-callout\; id="0"\; label="e"\; filenames="H2009102164293E00021.png,H2009102164293E00022.png"\; state="\{\{state\}\}">e</figure-callout>}}_{\mathrm{0,0}}\left[n\right]}{M}$

In the formula, M is the port number of time-interleaved acquisition system, T _sBe the sampling clock cycle of time-interleaved acquisition system, n is a sampled point.

2), passage 0, i.e. ADC ₀The image data y[Mn of output], get and deliver to after the negative value in the adder and ADC _mThe image data y[Mn+m of output] carry out addition, obtain interchannel deviation signal e _{M, 0}[n]:

e _m，0[n]＝y[Mn+m]-y[Mn]

In the formula, m=1～(M-1);

3), with desirable sampled signal x (nT _s) single order derived function x ' (nT _s) and the sampling clock period T _sProduct T _sX ' (nT _s) send in another multiplier and estimate with the sampling interval non-uniformity Multiply each other, and then output in the adder and product T _sX ' (nT _s) addition; The result of addition

After getting negative value, send in the lowest mean square iteration module, promptly among the LMS with interchannel deviation signal e _{M, 0}After [n] addition, the sampling interval non-uniformity is estimated Carry out the lowest mean square iteration, iterations is k, makes error function

The mean square error minimum, obtain k the sampling interval non-uniformity after the iteration and estimate

4), simultaneously, multiplier multiplied result in step 3) is error component e _m[n]:

$e_m\left[n\right]\&ap;{\hat{r}}_m^k{T}_s{x}^{\&prime;}\left(n{T}_s\right)$

The error component e of each passage _m[n] constitutes time-interleaved acquisition system heterogenicity error component e[n];

5), with heterogenicity error component e[n] get negative value, send in the adder output y[n then with time-interleaved acquisition system] addition, obtain the desirable sampled signal x (nT of reconstruct _s):

x(nT _s)＝y[n]-e[n]。

For adaptive approach, though system's initial parameter the unknown is constantly adjusted by said method, the uncertain influence to system performance of system's initial parameter will progressively reduce, after in the time of through one section, system the most automatically adjust to expect consistent.Do not need special calibrating signal like this, the base deviation is used for reconstruct when only needing unknown measured signal to estimate, and amount of calculation is little, is suitable for engineering and uses.

Example

In the present embodiment,, realize the 500MSPS data acquisition, import the 20MHz sine wave signal respectively before and after the signal reconstruction, image data is carried out the spectrum analysis result as shown in Figures 2 and 3 at the parallel alternating sampling system of 8-bit ADC model construction binary channels.

Fig. 2 is not reconstructed the spectrum analysis figure of the sampled data of output for time-interleaved acquisition system.

As shown in Figure 2, because the problem of aspects such as wiring and clock delay has caused the sampled data of time-interleaved collection that bigger time mismatch error is arranged.

Fig. 3 is reconstructed the spectrum analysis figure of the sampled data of output for time-interleaved acquisition system

After the reconstruct of process to the sampled data of time-interleaved acquisition system output, the desirable sampled signal x (nT of the reconstruct that obtains _s) base offset component when having removed to a great extent, as shown in Figure 3, can be clear that the desirable sampled signal x (nT of reconstruct _s) spectrum component of error percentage greatly reduces, frequency domain figure becomes very " totally ".

Fig. 4 is a mismatch error estimation procedure comparison diagram

As shown in Figure 4, obtain through adaptive iteration ${\hat{r}}_1^k=0.1758,$ Only need to carry out iteration 250 times gathering about 250 sampled points, behind promptly about 0.5 μ s, interative computation just can realize that speed is fast to time estimation heterogeneous; Simultaneously, only need 2 multiplyings in each interative computation, amount of calculation is little, need not to design especially reconfigurable filter in the restructuring procedure, has reduced system design difficulty and resource consumption.

The present invention is to the analysis of systematic error component, realized a kind ofly based on adaptive control, can realize simultaneously in the accurate estimation of error the algorithm of signal reconstruction helping the raising of systematic function; Its The Hardware Design difficulty is low, and operand is little, has improved the algorithm implementation efficiency; Need not to increase under the situation of extra calibrating signal, can change because of the error parameter that aging or environmental factor cause from motion tracking.Experiment showed, that this invention has remedied the not high defective of classical signal reconstructing method real-time, reduced the design difficulty of system, guaranteed the acquisition precision of system.Simultaneously, this invention has reduced hardware designs difficulty and cost, has good market popularization value.

Although above the illustrative embodiment of the present invention is described; so that the technical staff of present technique neck understands the present invention; but should be clear; the invention is not restricted to the scope of embodiment; to those skilled in the art; as long as various variations appended claim limit and the spirit and scope of the present invention determined in, these variations are conspicuous, all utilize innovation and creation that the present invention conceives all at the row of protection.

Claims (2)

1. the live signal reconstructing method of a time-interleaved acquisition system may further comprise the steps:

(1), time-interleaved acquisition system is sampled to input signal x (t), if passage 0 is a reference channel, image data y[Mn with passage 0 output] deduct the image data y[M (n-1) in M sampling clock cycle of this passage output delay], obtain the sampled data difference e of passage 0 adjacent moment _0,0[n]:

e _0，0[n]＝y[Mn]-y[M(n-1)]

Then, with sampled data difference e _0,0[n] multiply by 1/M, obtains desirable sampled signal x (nT _s) single order derived function x ' (nT _s) and the sampling clock period T _sProduct T _sX ' (nT _s):

$T_s{x}^{\&prime;}\left(n{T}_s\right)\&ap;\frac{e_{\mathrm{0,0}}\left[n\right]}{M}$

In the formula, M is the port number of time-interleaved acquisition system, T _sBe the sampling clock cycle of time-interleaved acquisition system, n is a sampled point;

(2), with the image data y[Mn+m of passage m output] deduct the image data y[Mn of passage 0 output], obtain interchannel deviation signal e _{M, 0}[n]:

e _m，0[n]＝y[Mn+m]-y[Mn]

In the formula, m=1～(M-1);

(3), the desirable sampled signal x (nT that obtains according to step (1) _s) single order derived function x ' (nT _s) and the sampling clock period T _sProduct T _sX ' (nT _s) and the interchannel deviation signal e that obtains of step (2) _{M, 0}[n] obtains following error function

${\hat{e}}_m\left[n\right]=e_{m,0}\left[n\right]-(1+{\hat{r}}_m)T_s{x}^{\&prime;}\left(\mathrm{Mn}{T}_s\right)$

In the formula,

For the sampling interval non-uniformity is estimated;

The sampling interval non-uniformity is estimated

Carry out the lowest mean square iteration, iterations is k, makes error function The mean square error minimum, obtain k the sampling interval non-uniformity after the iteration and estimate

(4), the sampling interval non-uniformity after k the iteration that obtains according to step (3) is estimated

And the desirable sampled signal x (nT that obtains of step (1) _s) single order derived function x ' (nT _s), obtain error component e _m[n]:

$e_m\left[n\right]\&ap;{\hat{r}}_m^k{T}_s{x}^{\&prime;}\left(n{T}_s\right)$

The error component e of each passage _m[n] constitutes time-interleaved acquisition system heterogenicity error component e[n];

(5), with the collection of time-interleaved acquisition system output y[n] deduct the heterogenicity error component e[n that step (4) obtains], obtain the desirable sampled signal x (nT of reconstruct _s):

x(nT _s)＝y[n]-e[n]。

2. live signal reconstructing method according to claim 1 is characterized in that, described iterations k is 250 times.

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