Katech AIS Test and Analysis System

Support

Support Information 1

Power Supply Requirements for KATAS AIS Receivers

AIS Receiver 1 and USB powered versions of AIS Receiver/Decoder 1

These units are powered from +5V DC from the computer to which the USB cable is connected. As the receiver requires the computer to operate, there should be no need for an alternative power supply. The receiver's internal voltage regulator is non-isolated which means that the negative pole of the supply input is at the same potential as the aerial and RS232 or audio return connections. If the unit is used on-board a small vessel without an ac mains supply, it is possible that the computer's negative return from its power supply actually connects directly to the boat's battery system. If this is so, it is important to ensure that the signal return from the aerial cable (the co-axial cable's screen connection) cannot connect to the boat's metalwork. If this is allowed to happen, then there may be a detrimental effect on other electronic on-board systems caused by power supply currents taking an alternative route through the boat's metalwork rather than through the intended cables. Users of the serial version of AIS Receiver/Decoder 1 can use an optional mains power supply if the product is in use with an older computer that has no USB interface, see part number page.

AIS Ship Monitor 1 & AIS Ship Monitor 2 (Land-use Range)

As these units are intended for land use, they were designed without the requirement to have to have a fully galvanically isolated power supply. The units require a stabilised +12V supply to operate correctly and this is provided for by the supplied wall cube mains power supply. Each receiver is supplied with one of two types of wall cube, either a 240V ac linear type with a UK mains plug or a wide input switched-mode type with a variety of adapters to suit most country's socket requirements. Despite the intended use, some users may still wish to use these receivers whilst at sea. If the vessel has a source of ac mains, then it is highly recommended that the supplied wall cube be used. If there is no alternative to operating the units whilst at sea on a dc-only boat, the unit must be powered from an external galvanically isolated switched-mode converter at the appropriate input range (typically 9-18V, 18-36V or 9-36V). The output must be 12V DC, a rating of 10W will be adequate. The boat's battery supply MUST NOT be connected to the dc power socket on the top of the receiver.

AIS Sea Scope 1, 2, Plus & 1900 (Marine-use Range)

These units are designed for maritime use and contain a galvanically isolated switched-mode converter that makes them very suitable for direct connection to the boat's dc voltage supply via a suitable fuse or circuit breaker. The converter has an input range of between 9-36V and is rated at 10W. It must be remembered however that this galvanic isolation may be defeated by the connection of a computer that is powered directly from the boat's batteries, perhaps via a car-type cigar lighter plug etc. The receiver has a secondary 12V output to power a GPS receiver from the isolated source but this supply cannot provide the power required to supply a whole PC computer system. The receiver's aluminium housing should be connected to the boat's metalwork via the rear panel earth terminal for best screening effect.