插值问题

bingely

一般所见到的都是信号插值问题，但对于噪声好像没有这方面的处理，不知道对低信噪比的回波插值处理可以否？噪声插值后其类型应该是发生变化的吧…………

yaoguo2

你是对什么信号进行插值呢？我没太看明白

是对“低信噪比的回波”进行“噪声插值”吗？

bingely

呵呵，是接收信号，我在处理的时候发现点数不够，想增加点数，于是想插值，但对插值后的信号的变化没有什么概念，比如信号中的噪声经过插值会有什么变化呢？

yaoguo2

有点类似提高信号的采样率，
看下重采样理论

Galaxy163

根据比率插入相应的0点，然后低通滤波即可。
处理得好，信号特性基本没变化。

bingely

谢谢楼上！～
信号如果在满足采样定律的情况下肯定没问题，我现在担心的是噪声！
相关性和非相关噪声都会有什么变化呢？好像目前没有文献提到
只是对信号有说明

dailiangren

对，重采样理论。

Matlab中的resaple.

RESAMPLE  Change the sampling rate of a signal.
    Y = RESAMPLE(X,P,Q) resamples the sequence in vector X at P/Q times
    the original sample rate using a polyphase implementation.  Y is P/Q
    times the length of X (or the ceiling of this if P/Q is not an integer).  
    P and Q must be positive integers.

    RESAMPLE applies an anti-aliasing (lowpass) FIR filter to X during the
    resampling process, and compensates for the filter's delay.  The filter
    is designed using FIRLS.  RESAMPLE provides an easy-to-use alternative
    to UPFIRDN, which does not require you to supply a filter or compensate
    for the signal delay introduced by filtering.

    In its filtering process, RESAMPLE assumes the samples at times before
    and after the given samples in X are equal to zero. Thus large
    deviations from zero at the end points of the sequence X can cause
    inaccuracies in Y at its end points.

    Y = RESAMPLE(X,P,Q,N) uses a weighted sum of 2*N*max(1,Q/P) samples of X
    to compute each sample of Y.  The length of the FIR filter RESAMPLE applies
    is proportional to N; by increasing N you will get better accuracy at the
    expense of a longer computation time.  If you don't specify N, RESAMPLE uses
    N = 10 by default.  If you let N = 0, RESAMPLE performs a nearest
    neighbor interpolation; that is, the output Y(n) is X(round((n-1)*Q/P)+1)
    ( Y(n) = 0 if round((n-1)*Q/P)+1 > length(X) ).

    Y = RESAMPLE(X,P,Q,N,BTA) uses BTA as the BETA design parameter for the
    Kaiser window used to design the filter.  RESAMPLE uses BTA = 5 if
    you don't specify a value.

    Y = RESAMPLE(X,P,Q,B) uses B to filter X (after upsampling) if B is a
    vector of filter coefficients.  RESAMPLE assumes B has odd length and
    linear phase when compensating for the filter's delay; for even length
    filters, the delay is overcompensated by 1/2 sample.  For non-linear
    phase filters consider using UPFIRDN.

    [Y,B] = RESAMPLE(X,P,Q,...) returns in B the coefficients of the filter
    applied to X during the resampling process (after upsampling).

    If X is a matrix, RESAMPLE resamples the columns of X.

    See also upfirdn, interp, decimate, firls, kaiser, intfilt,
    mfilt/firsrc in the Filter Design Toolbox.

    Overloaded functions or methods (ones with the same name in other directories)
       help tscollection/resample.m
       help timeseries/resample.m
       help iddata/resample.m

    Reference page in Help browser
       doc resample

Galaxy163

信噪比不会有变化的。

bingely

谢谢楼上各位。信噪比无变化，有没有具体参考文献，或者是如何理解呢？
呵呵，敬请指教