The following sections contain information relating to all the devices required for the GPS Locator Drifter Buoy system. This includes both the transmitting and receiving ends. Because specific model numbers and other product information are considered proprietary, they are not included.
All transmissions were from the GPS Locator Drifter Buoy. The equipment of the transmission system was inserted into the hull of the buoy. Below is a block diagram of this system.
There are three main components to this system, as shown in the block diagram. Each of the following links contains more detailed information on each component.
Component 1: The Electronic System
Component 2: The VHF Marine Transceiver
Component 3: The VHF Antenna
In order to conserve battery power, transmissions only occurred at a set interval of time. Therefore, if the transmission interval is 30 seconds, the system will last 15.4 Hrs, which is an adequate length of time for one day of ocean current research, which is the purpose of the buoy. This 30 second interval was calculated using a POWER BUDGET.
Because the original electronic system did not contain the VHF Marine Transceiver, the hull of the buoy had to be extended to accommodate the new equipment. Therefore, additional PVC piping was obtained to allow the new system to fit into the buoy's hull and be sealed tightly.
The receiver, which is located on the boat, is simple. Once transmitted, the GPS string (which contains information about the buoy's exact location) is then picked up by the receiving VHF antenna. The block diagram below shows the receiving system.
A VHF Marine Transceiver with its standard antenna removed is connected instead to the more powerful VHF antenna. To connect the transceiver to the Personal Computer (PC), a cable with a microphone jack on one end and a serial connector on the other was constructed. The PC was equipped with HyperTerminal in order to view and save the GPS string being received.
To communicate correctly with the buoy, HyperTerminal must be configured as follows: