"Turn" matlab sampling function

Dyaddown

Function: Two-yuan sampling of time series, extracting one element from each element, and obtaining a descending sampling time series.

Format:

1.Y = Dyaddown (x, EVENODD)

When evenodd=0, the second element in X starts sampling (even sampling), and when evenodd=1, the first element in X starts sampling (odd sampling).

2.Y = Dyaddown (x)

EvenOdd default, press Evenodd=0

Dyadup

Function: Two-dollar interpolation of time series, inserting a 0 element every other element to get a time series.

Format:

1.Y = Dyadup (x, EVENODD)

When evenodd=0, the second element in X starts sampling (even sampling), and when evenodd=1, the first element in X starts sampling (odd sampling).

2.Y = Dyadup (x)

EvenOdd default, press Evenodd=0

Interp

Function: integer interpolation of time series makes the time series curve smoother.

Format:

1.Y = Interp (x, R)

Insert some data into X so that the length of the sequence y after interpolation is R times x.

2.Y = Interp (x, R, L, Alpha)

The length of the sequence y obtained after interpolation is R times x.

3.[y, b] = Interp (x, R, L, Alpha)

The coefficients of a low-pass interpolation filter are obtained at the same time after interpolation, and the length is 2rl+1.

Description

x--Time Series

r--multiple of the insertion point

l--Interpolation filter length

The cutoff frequency of the alpha--filter, 0<alpha<=1, assumes that the sampling frequency of the original sequence is 1 and the default is l=4,alpha=0.5.

y--the time column after interpolation

b--low-pass interpolation filter with a length of 2rl+1

Downsample

Function: resampling the time series, fetching some items in the original time series at a moderate interval, and obtaining a new sequence.

Format:

1.Y = downsample (x, N)

Starting with the first item, the equal interval n is sampled by x, and the resulting sequence is Y.

2.Y = downsample (x, N, Phase)

Starting with item phase+1, equal interval n is sampled by x, and the resulting sequence is Y, while 0<=phase<n.

Decimate

Function: integer multiple sampling processing of time series, so that the length of time series is reduced.

Format:

1.Y = Decimate (x, R)

Reduce the sampling frequency of time series X to the original 1/r, which is length (y) =length (x)/R. The 8-order Chebyshevi Low-pass filter compression band is adopted by default prior to extraction.

2.Y = Decimate (x, R, N)

N-Order Chebyshevi Low-pass filter is adopted.

3.Y = Decimate (x, R, ' Fir ')

The 30-Order Fir Low-pass filter is used to compress the frequency band, and the time series is extracted by integer times.

4.Y = Decimate (x, R, N, ' fir ')

Specifies that when the time series is taken as Integer times, the N-point Fir low-pass filter is used to compress the frequency band, and the time series is extracted by integer times.

Description

x--Time Series

r--sampling to reduce the multiple

n--Specifies the order of the Chebyshevi low-pass filter used

' Fir '--fir filter

Resample

Function: Resampling the time series .

Format:

1.Y = resample (x, p, Q)

Using a multiphase filter to resample the time series, the resulting sequence y is p/q times the length of the original sequence x, and P and q are positive integers. At this point, the anti-aliasing low-pass filter designed using the Fir method is used by default.

B=resample (x,90,250); % sample dropped from 250Hz to 90Hz, if 250 in front, is interpolated from 90Hz to 250Hz

2.Y = resample (x, p, q, N)

The time series is resampled with the Chebysheviir low-pass filter, the length of the filter is proportional to n, and the N default value is 10.

3.Y = resample (x, p, q, N, Beta)

Beta is a parameter that uses the Kaiser window when setting up a low-pass filter, with a default value of 5.

4.Y = resample (x, p, q, B)

b the coefficient vector of the filter during the re-sampling process.

5.[y, b] = resample (x, p, Q)

The output parameter b is the coefficient vector of the filter being used.

Description

x--Time Series

p, q--positive integer specifying a multiple of the length of the resampling.

The n--specifies the order of the Chebysheviir low-pass filter used, the length of the filter and the N-ratio column.

The beta--uses the parameters of the Kaiser window when designing the low-pass filter, and the default value is 5.

Original link: http://blog.sina.com.cn/s/blog_6163bdeb0102dvm9.html

"Turn" matlab sampling function