SonTek/YSI
Using Frequency Pressure Sensors with SonTek/YSI Systems (December 2001)
3
3.2. The Paroscientific Digiquartz (PAROSFREQ)
User requirements for deeper ratings (compared to
DRUCK
) and faster response (compared to
PAROS
) convinced SonTek to offer the Paroscientific digiquartz sensor with frequency output
(
PAROSFREQ
). Functionally, the interface for the
PAROSFREQ
is identical to the interface for the
DRUCK
, as both are frequency-based sensors. The
PAROSFREQ
sensors are available for ADP,
PC-ADP, and Hydra systems. The differences, when compared with a strain-gage sensor, are as
follows:
•
The
PAROSFREQ
is an absolute sensor. It reads 1 dbar in air; a strain gage reports 0 dbars.
•
Requires a special interface to sample the frequency signal.
•
Requires a special frequency splitter cable.
•
Sampling rate is limited to 10 Hz (ADVs and Hydras) because of the time required to sam-
ple the frequency signal with sufficient precision.
•
Requires a calibration (specific to each sensor) to be loaded into the processor (system CPU
or a user PC) to obtain valid pressure readings.
•
Available in 50-psia (
≈
22 dbar strain gage) and 100-psia (
≈
60-m strain gage) pressure ratings.
The structure of the calibration file corresponding to the
PAROSFREQ
sensor is similar to the
DRUCK
. For historic reasons,
PAROSFREQ
calibration file uses the .drk extension.
•
Pressure Sensor Serial Number
•
Oscillator Frequency (in Hz)
•
U0
•
N/A
•
N/A
•
N/A
•
N/A
•
Y1 Y2 Y3 N/A
•
C1 C2 C3 N/A
•
D1 D2 N/A N/A
•
T1 T2 T3 T4
•
N/A N/A N/A N/A
•
N/A N/A N/A N/A
Example – Paroscientific calibration file
p68888.drk
:
P68888
12.0000000E+06
5.880670
0.0
0.0
0.0
0.0
-3898.415 -10940.31 0.0 0.0
224.5927 6.013600 -245.2861 0.0
0.041219 0.0 0.0 0.0
27.94067 0.859765 20.65914 26.99304
0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0
ote: The U, Y, C, D, and T coefficients can
be found on the Paroscientific calibration sheet.
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