© Valeport Limited 2003
MIDAS Surveyor Operating Manual
Page 8
0420805d.doc
3.2
ANTENNAE
The GPS antenna is supplied with a mounting spar.
•
Pass the antenna cable through the spar, and screw the spar into the base of the antenna.
•
Loosen the fixing clamp sufficiently to allow the loop end to be placed over the spar. Tighten the nuts with a 13mm
spanner until the bracket is securely held.
•
The antenna may now be fitted to a suitable vertical pole on the vessel. The fixing clamp will accept a pole up to
50mm diameter. This should be fitted vertically above the transducer, in an open area with as clear a view of the
sky as possible.
•
Connect the antenna cable to the GPS Antenna connector on the main MIDAS Surveyor unit.
•
If the optional marine beacon receiver/antenna unit is supplied, this should be mounted as close as possible to the
main GPS antenna. A similar spar and clamping method will be used as for the main GPS Antenna. Connect this
cable to the External GPS / Differential input connector on the main MIDAS Surveyor unit.
3.3
BATTERIES
The system is fitted with 4 x 2.1Ah sealed lead acid batteries. These are shipped from Valeport fully charged, but the
user would be wise to recharge them before relying on them in a field deployment.
The system is designed so that it will always draw its operating power from these internal batteries. The system is
supplied with an external DC input lead, which should be used to charge the batteries. A DC input of 12 – 24vDC is
acceptable. The batteries will be trickle charged whether the unit is turned on or off; when off, the batteries should fully
recharge in approximately 8 hours
Power consumption of the unit will depend on exact configuration, including the number of transducers used, and
whether the LCD backlight is used. At worst, a fully charged set of batteries should last in excess of 24 hours without
recharging.
Typical Power consumption is:
Main system, including GPS (12 channel) and LCD screen
90mA @ 12v
Single transducer
45mA @ 12v
Second transducer
15mA @ 12v
Backlight (user variable, but typically)
50mA @ 12v
Total
200mA @ 12v
8.4Ah / 0.2A continuous drain = 42 hours.
Assume 75% efficiency (worst case) = 25½ hours.
Note that certain system features such as the internal clock and data logging parameters depend on the batteries being
connected. The instrument will automatically shut down with warning if the power drains too low, preserving enough life
to maintain these functions. However, if the batteries are disconnected, or the instrument is left unused and discharged
for a long time, the user may need to re-enter such setup functions before next use. Refer to the appropriate sections of the
manual.
