local domain and global domain

Hi there,

Could anyone kindly explain what the "local domain and global domain" is in signal analysis?

Aditionally, what does "data-driven" mean?

Thanks in advance,

Jan

Answer 1

[Shubham Khatri]

Hello,

Local domain usually means considering a small part or neighborhood section in a signal whereas global domain usually means considering the whole signal for analysis.

Data driven techniques are those where we try to analyse signal properties using the statistics available from signal data.

Hope it helps

[Walter Roberson]

local domain analysis often needs only a fixed amount of memory (once the parameters are defined), and often works either by frame (fixed size chuck) or as a "sliding window". Local domain analysis is therefore suited for real time streaming work with definable maximum delay.

Global domain analysis on the other hand needs the entire signal to be recorded first.

It is not uncommon that a number of global domain problems can be turned into local domain problems with larger margins of error, or as-if a high-pass filter had been used.

For example spectrograms are often implemented by taking a fairly limited number of samples (such as 64 or 128) and using discrete fft on them to identify short-term frequency peaks. The fewer samples used at a time, the faster you can pump out the results, but you lose the lower frequencies. If you were doing infrasonic work with elephants, ferrets, or whales, then that would probably not be acceptable.

[Jan Ali]

Thanks Walter. It was a great explaination. I appreciate it.

Meanwhile, do you have idea about eemd algorithm for signal analysis? If so, would you please share eemd code?

Thanks in advance,

[Walter Roberson]

Sorry, that is not a topic I have ever worked with.