OCEANO RT2500S/RT5000S Series – User Guide
VII.2.2
A
COUSTIC
T
RANSMISSION OF THE
P
RESSURE
M
EASUREMENT
The acoustic transmission of pressure measurement is enabled by selecting the link in
MMI BALI. There are two possible configurations in encoding the pressure measurement
by the acoustic link:
In that kind of application, the
CRF
is configured as a
M-FSK
pulse: this configuration is
displayed in the “Parameters update \ Transponder transmit… “ sub-routine of MMI BALI.
When receiving the acoustic order IIF, the ‘positioning’ pulse CRF is transmitted, followed
by the KF1 pulse that encodes the 4 LSB of pressure measurement.
This graph illustrates the acoustic transmission of pressure measurement:
Figure 20 – USBL transmitting cycle
CRF : Synchronization pulse (M-FSK)
The 12 bits measurement are partly ‘temporally’ transmitted, partly encoded by the costas
codes.
K0 : Time resolution =
2,5 ms
T1 : Temporal encoding of the
8 MSB
of the pressure measurement (T1 =
k
×
2,5 ms)
T0 : Minimal value of the temporal encoding :
350 ms
KF1: MFSK pulse that encodes the
4 LSB
of the pressure measurement in COSTAS
codes.
The encoding unit used in pressure measurement transmission is ‘2 dbar’.
Example: Pressure measurement =
$24A
→
Value to encode =
$ 12 5
→
Figure 21 - Example
USBL
MU–RT8x1–AN–001 Ed. M – September 2013
30
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