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APPENDIX E: POWER CONSUMPTION
This section provides the electrical power profile of the A3LA-RM. It does not describe every situation;
however, it does offer a starting point for users to continue their own development design. The actual usage
profile can vary for a number of reasons including manufacturing variation from unit-to-unit. Users are
reminded to optimize their setup to attain the lowest possible power consumption. Some of the setup
parameters to be carefully observed include:
1.
Have a clear view of the sky for the antenna—poor visibility of the sky is when a clear line-of-sight
is not available between the A3LA-RM and the satellites.
2.
Keep the antenna’s VSWR low—the higher the antenna VSWR the higher the current consumed by
the A3LA-RM.
3.
Keep the antenna cables’ loss to less than 3dB—the higher the antenna cable loss the higher the
current consumed by the A3LA-RM.
4.
Keep the power cable between the A3LA-RM and the power source as short as possible.
5.
Use both power input pins on the multi-interface connector.
Power consumption of the A3LA-RM can be divided into five distinct operating segments: (1) standby,
(2) data-switch/RUDICS call, (3) SBD transmission, (4) SMS transmission and audio call. Typical current
drawn and power consumption for these cases are shown in plots below.
The A3LA-RM is designed to accept input power at two different voltage ranges—either from 4.0V to
5.4V or from 5.0V to 32V. A different internal DC-DC converter is used for each range. In each figure below,
electrical profile for both ranges are displayed in separate curves.
The A3LA-RM can be connected to a DPL handset through an HRC-24-8R data kit to make voice calls.
The DPL handset requires 12V, which is supplied by the A3LA-RM through pin 2 of the multi-interface
connector. When the DPL handset is on with the backlight powered up, the DPL handset current drawn is
about 350mA at 12V or about 500mA at 5V. Therefore, when a DPL handset is connected to an A3LA-RM,
user must account for the added current drawn.
