MX521
An Advanced DGPS Navigation System
You can use the MX521 as a pure input device for position to 2m accuracy, with any computer, PDA or logic device. Using the MX521 with the MX420 display unit, allows your boat or machine to display position accuracy within about 2 metres. MX521 ... IMO Compliant Smart DGPS Receiver/Antenna

The MX Marine Smart Antenna is available as a standard GPS (MX521), or in a DGPS configuration (MX521D). The MX521 is capable of about 5 metre accuracy. The MX521D is capable of 2-meter DGPS accuracy, with the built-in dual-channel DGPS beacon receiver. Both units are designed to meet all requirements for commercial marine, mining or industrial applications. Made to brave the toughest environments over longer time periods, the MX521 series provide the best accuracy and reliability in the marketplace. Built-in high precision 12-channel GPS receiver 2-meter DGPS accuracy and better than 5 meters in autonomous GPS mode

You will need a power/data cable of appropriate length to connect the antenna to the MX420 display unit, or to your own computing device. The cable can be extended if necessary by using similar wire types. The cable terminates in a 10 pin connection at the antenna end, and bare wires at the MX420 display end. (The cable does not suit earlier model MX421 antenna with 8 pin connector.)
* 20m Antenna Cable $160 + GST = $176 * 40m Antenna Cable $270 + GST = $297 * 80m Antenna Cable $680 + GST = $748

Optional 5Hz update of position
Integrated dual channel beacon receiver and unique H-field beacon antenna design
Rugged enclosure to defy harsh conditions
Stainless steel threaded insert
Flush or pole mount
Entirely waterproof

Complete MX521 information as a PDF file

You can also use an autonomous GPS smart antenna, the MX421. View MX421 PDF file.