Please help a tinkerer. Searched for a thread but no luck. I have a Magellan active antenna, it looks like the ones I see on the web, but no cable connector, it has a small coax type cable. I would like to usb it to my laptop to make it a marine chart plotter. Ordering a cheap one from the web scares me because I want something truly weather proof and durable. The coax appears to just have a shield and core, how do I connect this to usb?