Yay! It looks like we're good to go on using the VTI pressure sensor.
This does mean that we'll need to do our own calibration runs near
vacuum, but that seems just fine.

Glenn, this means we're going to do some runs in Eric's vacuum chamber.
Can you arrange this soon, like in about 2 weeks?


-------- Original Message --------
Subject: Re: SCP1000 performance near a vacuum (< 30 kPa)
Date: Wed, 21 Nov 2007 20:52:55 +0200

Hello Andrew,

Here are some answers to you questions.

1. Output doesn't saturate to 30kPa value. In principle smallest value
is zero (DATARD8 = 0x00  and DATARD16 = 0x0000). In practice there is
some small offset value the output saturates.

2. Unfortunately I don't have much data to offer. We know that some
customers have been tested SCP1000 down to 100Pa (and even lower)
without problems and actually stated that output was quite linear.
However they haven't share test results with us so I can't comment how
linear it was.

3. Mechanical repeatability should be good so it should be possible to
compensate/linearize output at low pressure.

Hope this helps,


Ville Nurmiainen
Application Engineer
VTI Technologies, Inc.
Tel (313) 425 0850
Direct (313) 425 0849
Mobile (313) 641 0850
Fax (313) 425 0860

>>> Andrew Greenberg <[EMAIL PROTECTED]> 20.11.2007 2:17 >>>
Hello VTI,

We're interested in using the VTI in an aerospace application that can
reach large altitudes. However, there's no notes on what happens as the
SCP1000 crosses the 30 kPa minimum range. Clearly the ~19 bits on the
pressure sensor has the numeric range to go less than 30 kPa, so:

1. Does the pressure sensor just saturate at that numeric value?
2. Does the pressure output go non-linear at low pressures?
3. Even if it goes non-linear, might it be possible to linearize the low
pressure performance given a calibration run and then some kind of curve

Thanks so much,


Andrew Greenberg

Portland State Aerospace Society (http://psas.pdx.edu/)
[EMAIL PROTECTED]  P: 503.788.1343  C: 503.708.7711

Andrew Greenberg

Portland State Aerospace Society (http://psas.pdx.edu/)
[EMAIL PROTECTED]  P: 503.788.1343  C: 503.708.7711

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