Rhotheta RT-B77 HELB, Руководство пользователя

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RHOTHETA User Manual Personal Locator Beacon RT-B77
HELB
Page 18 of 26
7 Intelligent Power Management
It is an important feature of the RT-B77 to use the available power at its best in all possible
scenarios of use. Therefore a complex, intelligent power management is necessary for bat-
tery-driven mobile devices, in order to guarantee in e.g. very cold temperatures as well the
best compromise between high transmitting power (= wide range), long transmission period
and trouble-free use.
Short common technical background:
Each battery depends of its surrounding temperature. The internal battery resistance can rise
in case of very deep temperatures (e.g. -20°C) or at very old batteries (> 5-10 years). In that
case only a restricted quantity of current/power will be available any more. If this fact will not
be considered, the battery voltage can break down, which will cause poor utilization of power
and – worst case – even wrong function.
7.1 RT-B77 Power Management
Therefore all parameters of the RT-B77 are controlled by a very contrived power manage-
ment, in order to guarantee a power at its best at all times. Even during active emergency
transmission the unit reacts continuously to changing surrounding conditions. In a worst case
scenario the RT-B77 is being used e.g. on a ship’s deck at -10°C air temperature and +5°C
water temperature. In case of a Man Over Board emergency, the beacon will be bathed by
water and therefore even “slightly warmed up”, which leads immediately to a higher maxi-
mum top transmission power.
After having activated the RT-B77, it runs through several performance profiles for optimum
use.
There are three different, fully automatically regulated modes of transmission:

High Power Mode
with max. 2 Watt max. output power

Endurance Mode
with max. 1000 mW output power

Power Save Mode
with max. 400 mW output power
Normally (battery change done according to instruction, and temperatures higher than ap-
prox. -10°C) the RT-B77 goes always to the
High Power Mode
when being activated, in or-
der to guarantee an immediate, safe and reliable alarm. This is very important for an effective
and very fast rescue even under the worst conditions (transmitting antenna completely under
water with the Man Over Board is floating on his front, or cold water). After approx. 4 hours
the RT-B77 changes automatically to the
Endurance Mode
for a compromise between still
very high transmission power and a long transmission time. This is a very important period if
the own crew can’t do the rescue and if emergency services have to be led. After approx. 12
ATTENTION
The output power and the duration are highly dependent on the current tempera-
tures.