Katech AIS Test and Analysis System

Support

Support Information 2

Important aerial information

Both the portable and land based receiver ranges have a 50-ohm BNC socket for aerial connection whilst the units within the marine range have a 50-ohm SO-259 socket. Adapters can be optionally supplied for converting one series connector to another, if necessary. The aerial MUST NOT be shared with any other type of receiving or transmitting equipment; the AIS receiver must have its own aerial. If used on-board, the aerial should be arranged to be in a different horizontal plane to the main transmitting aerial and, ideally, spaced as far away from it as possible. For best reception performance, the AIS aerial should also be mounted as high as possible. Any vertically polarised aerial that covers the 162MHz band is suitable for KATAS AIS receivers, however, a highly recommended aerial for marine use is the Comrod model AV-7. The cable used should be type RG58 or URM43.

Output flow control for the serial port

All KATAS AIS receivers that have a serial port can utilise a scheme of hardware handshaking for flow control. In a very busy shipping area, AIS transmissions can arrive in very quick succession, and it is possible that some terminal types may lose characters whilst the data is being queued for display. To counter this possibility, a software pacing system has been implemented which will operate with all terminal types but there is also a switchable hardware handshaking facility, which allows greater throughput of data as long as the terminal is correctly configured and connected.

Most modern computers and software packages will not require the hardware handshaking facility and so it is disabled by default. Should it be required, it can be enabled by changing the position of an internal jumper and repowering the system. Two types of hardware handshaking are used, known as DTR/DSR or RTS/CTS.

The AIS Ship Monitor units can support both types of handshaking, selectable by a choice of internal cable form, set at manufacture. All units are being supplied with DTR/DSR handshaking as this is the mode used by the Wyse terminals used during software development. Units that use DTR/DSR handshaking have a blue sticker on the outside of the case near to the serial port whereas units that use RTS/CTS handshaking have a yellow sticker. Alternatively, if the label becomes detached, the internal serial port cable form has a sleeve that is coloured accordingly. Some serial port adapter leads within the KATAS range may also have a blue or yellow sleeve. This simply means that, should hardware handshaking of the receiver be enabled, the appropriate handshaking connections within the cable, according to the sleeve colour, will be passed through to the peripheral device.

Serial interface AIS Receiver/Decoder 1 units can only use DTR/DSR handshaking. Some computer systems require RTS/CTS handshaking, and if this is needed, an external dongle is available which switches around the cable connections, see parts list for details.

Previous | Next