Re-radiating Antenna

[+Bull Moose]

I'm thinking about getting a re-radiating antenna from PC Mobile. I'm not very familiar with some of the more technical aspects, though and have two questions:

 

1. What's the difference between the two types (GAS76X, GAS76B) offered? I have a Magellan Meridian Gold, if that makes any difference.

 

2. A more general question: Since GPS works on small differences in time, why would getting a signal from both the re-radiating antenna and directly from a bird not screw up the location calculations?

[peter]

1. For the re-radiating setup you're buying two components - an antenna and the reradiator. The two units are connected by a cable with a connector which can be either BNC-type (the 'B' units) or MCX-type (the 'X' units). If you don't have any GPS units that accept an external antenna directly then I'd go with the MCX connector since it's much smaller - so I'd recommend the GARATX for you.

But people who might have both a III+ (which has a BNC connector) and a Meridian would probably choose the BNC style so they could use the antenna directly with the III+ or in combination with the reradiator for the Meridian.

 

2. It's best if you shield the Meridian's internal antenna from getting direct GPS signals. Models that accept external antenna inputs disconnect the internal antenna when the external is connected

[+Bull Moose]

It's best if you shield the Meridian's internal antenna from getting direct GPS signals.

How would I best do that? Make it a little tin-foil hat?

 

Thanks for the reply.

[peter]

Yes, that would do it - with the reradiating loop inside so its signals aren't blocked. In practice I suspect the signals from the reradiator are so much stronger than the direct signals that there usually isn't any issue, especially if used inside a car or other environment where the direct signals are weak.

[+Bull Moose]

Excellent.

Thanks for the help!

[+NightPilot]

GPS does work on time signals, but the external antenna makes no difference there. It doesn't take very long to go an eighth of an inch at the speed of light. Just use a rubber band to put the loop against your GPS antenna, and you're good to go. I use one on my Garmin Legend, and it makes a huge difference. It's wonderful while driving, because I don't have to keep the GPS in the windshield. I keep it on a homemade mount in a cup holder, where I can see it, and get max signal bars on 12 satellites most of the time, with good WAAS signals. In the woods the difference is even more dramatic, and I don't have to hold my GPS flat in my hand all the time.

[+Bull Moose]

I guess. When we're talking about signals from thousands of miles, the time for electrons to move through a wire for 10 feet should make no difference.