Re: comedi_command( ) for mccdaq pci 6034........... ERROR (Frank Mori Hess)

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On Friday 22 October 2004 01:08 pm, Ong Wee Liat wrote:
> Hi Frank,
>
> yup..i think i am pretty sure i fed in a sine wave of approximately 1
> kHz. It is between 1.045 - 1.067 kHz range as the display from the
> function generator and the oscilloscope differs slightly.

A 1.045-1.067kHz sine wave sampled at 1 kHz will appear as a 45-67 Hz sine 
wave.  It's called aliasing.

> Further i found some other issues with this command using this driver
> which i have posted it too.

By default, the driver transfers data in fixed size blocks.  Use the 
TRIG_WAKE_EOS flag if you want less latency.  The command takes less time 
to complete with more channels because it takes less time to fill one 
block worth of data (the excess samples are discarded).

- -- 
Frank

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Received on 2004-10-22Z21:35:13