YSI SonTek ADVField

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
N
ote: The U, Y, C, D, and T coefficients can
be found on the Paroscientific calibration sheet.