PSN-L Email List Message

Subject: Sample Rate Question
From: "Randall Pratt" rpratt@.............
Date: Tue, 24 Jul 2012 09:02:46 -0500


Hi All,

 

I am looking at my noise and aliasing and it brings up a question on sample
rates.

 

Using a Dataq 154 and their collection software the data rate is set as a
reduction from the basic 240 sps either by averaging such as using 40
samples to get 6 sps, by taking the max value of the 40 samples or by one of
several other options .  My understanding is that the averaging method
provides some reduction of noise and aliasing and would be the better option
from that respect and also because the sample would be taken at a set time
period versus a max value occurring anywhere during the 40 sample period.
Also by sampling at 240 and using a factor of 240 to average and reduce the
rate will result in 60 hz aliasing into the nyquist bin with little effect
on frequencies of interest.

 

The question then is this.  When I log using AmaSeis and the DI-154 at 6 sps
do I get an average, a max of a group of samples or a specific Amaseis
controlled sample rate of single 6 sps samples?  

 

Randy

 












Hi All,

 

I am looking at my noise and aliasing and it brings = up a question on sample rates.

 

Using a Dataq 154 and their collection software the = data rate is set as a reduction from the basic 240 sps either by averaging = such as using 40 samples to get 6 sps, by taking the max value of the 40 samples or by = one of several other options .  My understanding is that the averaging = method provides some reduction of noise and aliasing and would be the better = option from that respect and also because the sample would be taken at a set = time period versus a max value occurring anywhere during the 40 sample = period.  Also by sampling at 240 and using a factor of 240 to average and reduce = the rate will result in 60 hz aliasing into the nyquist bin with little = effect on frequencies of interest.

 

The question then is this.  When I log using = AmaSeis and the DI-154 at 6 sps do I get an average, a max of a group of samples or = a specific Amaseis controlled sample rate of single 6 sps samples?  =

 

Randy

 


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