From: Bob McClure 
To: psnlist 
Sent: Tue, 24 Jul 2012 18:05
Subject: Re: Sample Rate Question


  The Amaseis processing works the same as Dataq's. It samples at 240 sampl=
es per second and averages to data down to the user's acquisition rate.=20
Bob

Hi Bob,=20

 =20
    Are you quite sure ? 240 SPS is the maximum ADC sample rate from ALL 4 =
inputs. The earlier Dataq ADCs did not do ANY signal averaging for lower co=
nversion rates, provide min or max values, RMS readings, etc., although I s=
ee it on some current ADCs.=20

    Regards,=20

    Chris

=20


On Tue, Jul 24, 2012 at 10:02 AM, Randall Pratt  wrot=
e:


Hi All,
=20
I am looking at my noise and aliasing and it brings up a question on sample=
 rates.
=20
Using a Dataq 154 and their collection software the data rate is set as a r=
eduction from the basic 240 sps either by averaging such as using 40 sample=
s to get 6 sps, by taking the max value of the 40 samples or by one of seve=
ral other options .  My understanding is that the averaging method provides=
 some reduction of noise and aliasing and would be the better option from t=
hat 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 b=
y 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 fr=
equencies of interest.
=20
The question then is this.  When I log using AmaSeis and the DI-154 at 6 sp=
s do I get an average, a max of a group of samples or a specific Amaseis co=
ntrolled sample rate of single 6 sps samples? =20
=20
Randy
=20







=20













From: Bob McClure <bobmcclure90@.........>


To: psnlist <psnlist@..............>


Sent: Tue, 24 Jul 2012 18:05


Subject: Re: Sample Rate Question








  The Amaseis processing =
works the same as Dataq's. It samples at 240 samples per second and average=
s to data down to the user's acquisition rate.=20


Bob







Hi Bob, 


  

    Are you quite sure ? 240 SPS =
is the maximum ADC sample rate from ALL 4 inputs. The earlier Dataq ADCs di=
d not do ANY signal averaging for lower conversion rates, provide min or ma=
x values, RMS readings, etc., although I see it on some current ADCs. =


 

    Regards, 

 

    Chris




 









On Tue, Jul 24, 2012 at 10:02 AM, Randall Pratt =
<rpratt@.......
dco.net> wrote:












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 s=
amples or by one of several other options .  My understanding is that =
the averaging method provides some reduction of noise and aliasing and woul=
d 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 2=
40 to average and reduce the rate will result in 60 hz aliasing into the ny=
quist bin with little effect on frequencies of interest.




 




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




 




Randy