Tuesday, July 2, 2013

Building GPS stations


Objectives


To survive in Antarctica, the stations have to be completely autonomous and resist to the cold and windy conditions. 

To answer these requirements, we will set up a couple a solar panels that will recharge three batteries. Because of the polar night, the systems will hibernate through the winter period and, all going well, will recommence operation around August/September each year (when the sunlight is sufficient to recharge the batteries). An iridium modem and antenna will allow us to get the GPS (Global Positioning System) data transmitting them from Enderby Land back to Canberra. The structure has to be heavy and fixed to the rocks. The batteries, GPS and electronic circuit are protected in a insulated box, that should keep the warmth produced by the electronic equipment and the heaters.

The structure


Each element of the frame is logically numbered to facilitate their setting in the field. The structure is metallic, so heavy and resistant. It then has to be oriented in the Northern direction to provide the maximum solar light in a day.



Bianca installing the main frame on the roof


With the solar panels and the iridium antenna

The Electronic circuit


The circuit is installed in the insulated box and is composed of:
- One GPS
- Three batteries
- Three regulators
- A card frame composed of a small computer and a Power Controller
- An iridium modem
- Heaters, temperature probes etc...

The Solar panels will recharge the batteries. The Power Controller (PCON) will then separate the power between the Computer, the GPS and the modem. If any power cut occurs, a filter board will prevent any damage on the GPS or on the computer. 



The three batteries and regulators isolated in the box. The GPS has to find its place in there...


At the end, the system is sending every day the data acquired by the GPS, transformed into ASCII format and compressed by the computer, through the modem and iridium antenna. Away from the "wake-up hours", so when the computer is getting the data from the GPS and sending them via the iridium, the system is set to "sleeping mode" to reduce the power supply.

The card frame controlling the "waking" and "sleeping" state of the system and recording/processing the GPS data.

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