Remote Control System TT801 – User Guide
MU-TT801-AN rev.6 September 2009
44
III.4.6 C
ASE OF THE
P
RESSURE
M
EASUREMENT
With RT8x1 equipped with a 700 Bars Full scale pressure sensor, it is possible to
measure the pressure by telemetry. The option PRESSURE TELEMETRY ON should be
activated in the transponder.
Pressure measurement is accessible on individual acoustic interrogation (IIF) and the
acoustic response (CRF)
has to be configured as a
monochromatic
frequency.
When receiving the acoustic order IIF, the beacon transmits a first ‘positioning’ frequency
CRF, followed by a second identical monochromatic frequency CRF.
The graph on Figure 9 illustrates the acoustic transmission of pressure measurement.
Figure 9 - Pressure Measurement Diagram
CRF: Synchronization pulse (Monochromatic)
The 12 most significant bits (MSB) of the pressure measurement are transmitted using a
pulse-to-pulse time modulation (Time T).
T0: Delay that has a minimal value of the temporal encoding : 2 s
T1: Temporal encoding of the 12 MSB of the pressure measurement with a time resolution
of 2,442 ms (T1 = K
×
2,442 ms; K is the pressure measurement)
Note
The encoding unit used for pressure measurement transmission is ‘2 dbars’.
We can notice that the measurement cycle is carried out after measurement encoding:
Every transmission is followed by a pressure measurement acquisition, and this value will
be transmitted at next interrogation. This implies a ‘shift back’ between acoustic
interrogations and pressure measurements which are transmitted.
The Figure 10 sums up the procedure to perform in IMMEDIATE TRANSMIT menu.
Follow the procedure described in the section III.4.2.1 with the specific parameters:
•
Step 2 choose IIF
•
Step 7 choose MONO, then the PRESSURE MEAS option appears
•
Set the PRESSURE MEAS to ON
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