PSN-L Email List Message

Subject: Re: A/D
From: Stephen & Kathy skmort@..........
Date: Sun, 10 Mar 2002 18:03:33 -0800

Hi Kareem,   on the Dataq 150-RS that I use, there are two ranges of sensitivity,
which they call "gain".  The 10.0 volt and the 0.100 volt; which is found under
"edit" then "channel settings",,  available only when you are in "set-up" mode. 
Within those two ranges or gain modes, you can also set the limits,, found under
"edit" then "fixed calibration".   Since my seismo amp can put out plus and minus
10.0 volts, I've set it to the 10 volt range and  have the limits, on that
channel, set to plus and minus 10 volts.  For the moment, the other channel
monitors my GPS time signal and goes from 0 to about .4 volts in pulses. I have
that channel also set to the 10 volt range, but the limits are set to plus and
minus 1 volt,,,   I could have set it to plus one volt and zero.   From there, I
can use the up and down arrows (not page up and down, on mine that changes the
time compression), to zoom in or out the waveform range that is visible on the
screen,,,   If I use the down arrow I can show up to +/- 40 volts, which has no
meaning since the dataq is limited to +/- 10 volt in the first place and my signal
electrical limits, (the amp), are set to +/- 10 volts in the second place,,  but
if I use the up arrow I can zoom in and expand the waveform so that the screen
sees the upper and lower limits as +/- 0.313 volts!!   On my channel that the
limits are set to +/- 1 volt, I can expand the waveform so that the upper and
lower range on the screen are +/- 0.0313 volts,,  (the so called "gain" is still
10.0 volts, the same as the other channel, but the limits are +/- 1.0 volts).  
I've never used the 0.100 range but you should be able to see some very small
signals at that range!!  For my normal recording and viewing, I set the visible
range, ("zoom" if you will), to +/- 1.250 volts,  if a trace comes in that is off
the screen, I simply hit the down arrow to shrink the waveform.   I set it at this
zoom so that I can monitor the normal background noise.  The normal background
noise is around +/- 0.050 volts,,,   but with storms off the west coast of USA
(about 100 miles from my sensor) the background noise can get as high as +/- 0.130
volts!  I do have an adjustable gain amplifier between my very crude sensor and my
dataq, which is set to approx. 10,000.   I probably could have used an amplifier
with a gain of 100 and then used the 0.100 range on the dataq for the same visual
effect on the screen.  One of these days I'll get around to trying it!!
for Dataq DI-150RS
there are two range or gain modes,   (10.00 and 0.100)
within those range modes you can set the range limits,
within the range limits, you have 8 zoom levels, (2 up 5 down plus the limit, set
by the limit and is either doubled or halved from the limit)
In theory you could set the dataq to the 0.100 gain mode,,  set the limit to 0.010
and be able to zoom to a full screen range of +/- 0.000313 volts, but you will
probably be mostly monitoring the dataq internal offset and or noise!!????
Hope this helps,
  PSN Station #55
  near Pilot Hill Ca
  38.828N  120.979W

Kareem wrote:
> I have the DATAQ 154-RS, the newer version. I'm not sure how to
> calibrate it. Can anyone help? I have it connected to a Kinemetrics PS2
> system. It's connected to pin "C" of the Ps2. I think that I have it
> connected properly because if I increase the gain on the PS2 the DataQ
> software responds. But there signal is not behaving as the pin on the
> drum is. It seems the pin will continuously move even when the gain is
> set low. It's not until I increase the gain on the Ps2 all the way to
> end of the dial, that I begin to actually see the signal in the DataQ
> software respond. But shouldn't both pin and signal on my screen behave
> nearly the same? Also I can't get the AmaSeis software to pickup the
> signal. Any tips?

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