How can determine the sampling frequency from a time series data?

i need the sampling frequenccy of a give time series data. it is a 1x31225 time data if i choose any two point say x(:,1) and x(:,2)

1/x(:,2)-x(:,1) does not give a likely sampling frequency, it gives about 0.2144 for instance. please help out

Answer 1

[Star Strider]

All may not be lost. When I searched for information on .sif files, I came up with a number of different definitions, including Andor Scan Information File (there are at least two TMW File Exchange entries for those), and Cytoscape Simple Interaction Format. (They are also Windows Setup Information Files, but those likely aren't the ones you are interested in.)

What generated your .sif file, and what does it contain? How many rows and columns should it have? If it is supposed to be a matrix rather than a vector, it may be possible to get the time data (if there is a time vector in the matrix) by doing reshape on it.

Answer 2

[Azzi Abdelmalek]

 if x(:,1) is time and x(:,2) is your signal

then, if the sample frequency is constante

 f=1/((x(2,1)-x(1,1))

[Lisa Justin]

no time given just the signal

[Azzi Abdelmalek]

how could you find a sample frequency if you have'nt a vector time? it's not possible.

[Lisa Justin]

 no vector time given.

[Lisa Justin]

i guess it was lost from conversion from a SIF file. but i have only the converted file, any ideas

[Azzi Abdelmalek]

Without a vector time, we can't find your sample frequency. I can't guess what happens to your file.