From: Rob Sacks (editor_at_realization.org)
Date: 2001-04-20 19:10:52
Hi folks,
I just checked my server stats and see that my
program, ElectricGuru, has been downloaded
a few times.
In case anybody is using it with the BrainMaster,
there are two things you should know:
1. With the BrainMaster (only with the BrainMaster),
the frequencies display about five percent higher than
they really are. This goes for the bar graphs and
threshhold settings.
In other words, when you see
a 10 Hz bar, or you set a 10 Hz threshhold, you are
really dealing with 9.5 Hz (approximately). The
reason for this is that FFT algorithms like to handle
data 256 chunks at a time, but the BM produces
only about 244 samples a second, so the program
takes a little more than a second's worth of data at
a time. Thus it sees more cycles in the examined
time period than occurred during a one-second period.
However, for simplicity, I have allowed the program
to believe it is examining the data one second at
a time.
If this program is ever distributed to the public for
use with the BrainMaster, then of course it needs
to be modified so the numbers display accurately.
However, I didn't so yet because I couldn't figure
out the best way to make the necessary adjustment.
Interpolation would slow things down, and re-labeling
the bars would be misleading (since it implies higher
resolution than actually exists). I suspect there must
be some standard method for handling this situation
(it's obviously common) but I don't know what it
is. Maybe somebody here can tell me.
The trace graph (waveform) is accurate with
all machines including the BM (so far as I know).
2. After you use the program with the BrainMaster,
before exiting the program, be sure to click the
yellow Snail icon (looks like a French horn) to
reset the BrainMaster to the slow speed expected
by the regular BrainMaster software written by
Tom Collura. Unfortunately, the regular software
doesn't set the speed itself, that's why this kludge is
necessary. If you don't do this, it will look like
something is broken when you try to run the regular
software. But nothing is really broken; all you need
to do is run ElectricGuru and use the Snail icon.
You can do this at any time.
Regards,
Rob
This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:29 BST