GPS Internal Antennae

[dflorea]

This is just a comment/ observation that I made while in a west marine store a few days back. i was looking at GPS and noticed that the ones with internal antennaes 176 276 worked well even though they were mounted on steele shelves a a brick wall behind them. the sale rep pointed this out as well. I dont think an elctronic box with open front hatch would stop the signal.

 

[JB]

Re: GPS Internal Antennae

Interesting observation, DFloria. I wonder how long it took them to initialize.<br /><br />My experience has been that the 12 channel receivers can find three satellites (close together) to make a fix with a very small view of the sky, but if they can see 8 or 12 satellites they give a much faster and more accurate fix. My Garmin 162 is far faster and more accurate on top of my boat console than on the dash of my truck, where it sees half the sky at best.<br /><br />I would not conclude from your observation that internal antennae will perform as well if partially shielded as if having a full sky view.

 

[Dunaruna]

Re: GPS Internal Antennae

My first GPS (dash mounted) had an internal antenna and I (sometimes) locked on to 3 or 4 sats inside my steel roofed workshop. The container door was open, maybe that made a difference. Dunno.<br /><br />Aldo

 

[MickLane]

Re: GPS Internal Antennae

I have an etrex legend. It works fine in the car while I am travelling. But in my Sea Nymph Great Lakes Special, sitting on the console, with nothing between it and the sky but the boat windshield, it loses the signal. I am not sure what the problem is, but if I move it to where there is no windshield, it acquires and operates fine. I can't figure out why it works in the closed car through the glass, but not on an essentially open boat with nothing but a boat windshield. Could it be the aluminum nature of the boat? Puzzling.<br /><br />Mick

 

[Constancia]

Re: GPS Internal Antennae

My main GPS (Garmin 128) went out this past week during a fishing trip to San Carlos, Mexico. Could not acquire satellites, but all other pages displayed and worked fine. I suspect the antenna module mounted on my T-top went bad. Have a new one on order. <br /><br />In the meantime, I used my back-up, a Garmin 76 GPSmap. Was able to lay it right on the center console and power it from the cigarette lighter. It was able to aquire and worked just fine, even though it was under the T-top. My boat is a 23' ft. aluminum Bayrunner-Baja, so I don't think the aluminum in your boat should present any problem. <br />

 

[swist]

Re: GPS Internal Antennae

Agree with earlier post - my Garmin GPS152 external antenna acquires so many satellites so quickly it's amazing - between that and WAAS, I find I have to set waypoints on buoys a few yards off the buoy. If not I am GUARANTEED to run into it in pea soup.** Of course I could put the radar on, but with WAAS GPS I'm finding it radar less useful than before - it's major feature it that it sees other boats, but I am in a sparsely boated area. <br /><br />** A friend who's an aircraft pilot told me that today's navigation aids are so accurate that if two planes are accidentally assigned the same altitude and intersecting trajectories they are pretty much assured of crashing. In the good old days ATC got off the hook on some of these errors because the slop in the system made it unlikely that the planes would come that close.

 

[Boatist]

Re: GPS Internal Antennae

My Garmin GPSMAP 76 works well in my car and on the boat under a canvas top and behind all the windows.<br />With 24 birds up you should be able to get 3 birds to get a fix with very little view of the sky. However to really test how well it recieves see if you can get the two WAAS birds that give error correction. These are Garmin # 47 and # 35. The WAAS birds are over the equator and out in the pacific and out in the altanic. POR (pacific ocean region) garmin bird 47 is at 0 degrees Latitude and 178 degrees East longitude. AOR (alantic ocean region) is a 0 degres latitude and 54 degrees West longitude. So you can see these birds are not over head but low on the horizon and a good distance away if you are in the USA.