gps question

[mattttt25]

20' center console with a custom hard top (ss tubing and fiberglass top). plan on purchasing and instaling a garmin gpsmap 162.<br /><br />i was set on buying the unit with the external antenna and throwing the antenna on top of the hardtop. but looking at the tube running from the elctronics box to the console, it doesn't look like i can fit the fish the cable through (already filled with power lines). i may still try but will be stuck if i can't.<br /><br />other alternative is to purchase the unit with the internal antenna. anyone have an opinion/experience with this? will the hardtop block/degrade signals? i've used an old handheld under the top and it seemed to work fine. don't want to get bad signal strength and disable the waas. thanks-

 

[JB]

Re: gps question

Ahoy, Mattttt.<br /><br />I have the internal antenna on my GPSMAP162 mounted on the console and it degrades if the Bimini is up.<br /><br />I would suggest an external antenna on top.

 

[mattttt25]

Re: gps question

thanks jb, not what i wanted to hear but oh well. guess i'll take another look at that tubing and maybe make a test run with another cord. thanks-

 

[Troy_from _Oz]

Re: gps question

matt - would it be too difficult to run another length of tubing next to the existing one? It will then be nice and neat. <br /><br />Experience differs with fibreglass and signal attenuation. Ive had strong GPS signals inside my old landcruiser that had a fibreglass roof and roof upholstry. WAAS signals im not too sure about though.<br /><br />cheers - T

 

[Boatist]

Re: gps question

Mattttt<br />My Garmin GPSMAP 76 works really well in the car with a metal roof. I think your would work well also of course will be better with a external antenna. I am guessing you are about 39 degrees North Lat and 76 degrees West Lon. If so then can only see one WAAS bird. Alantic Ocean Region (AOR) SAT 35 over equator at 55.5 degrees West. Since we can receive it from west coast should be quite strong bird from your location. The other WAAS Bird Pacific (POR) Sat 47 you can not view anyway. It location is 180 degrees west and of course over the equator but in the USA only the West coast can see it. Do you think they will re introduce Slective availablity again when the war starts so IROC can not use GPS??

 

[BillP]

Re: gps question

Wow, I thought all new gps units were strong enough to get signals through a boat top. My old 12 channel Eagle handheld locks on through the roof of my house!

 

[Troy_from _Oz]

Re: gps question

Boatist, I think the official line is that the US DoD will use 'selective denial' in the case of regional conflict. I believe the theory will be to switch the signals on/off for the region, however I question this ability knowing the footprint coverage typically available with the GPS satellites. Although the sats do have multiple antennas, so maybe they switch certain ones on/off at any given time. I think anything could happen though. Medium case scenario will be the reintroduction of S/A. Worst case scenario will be that the civilian frequency will be shut off completely (in the region??). This will depend on how many military receivers the DoD has available at the time. <br /><br />BillP - the signals from GPS satellites are really weak (the strength has been likened to a bees f@rt). The signal itself is unlikely to be propagagting through your roof (although I dont know what your roof material is). What is probably happening though, which is pretty cool, is that the signals are being reflected off objects outside through your windows and open doors. This is the same principle used by the 911 push in the states that is seeing GPS receivers installed in (all?) new mobile phones... Its all pretty high-tech stuff. <br /><br />cheers - T

 

[mattttt25]

Re: gps question

wow, lots of info. as far as installing a new tube, doubt that will happen. this is a real nice custom hardtop with electronics box. doubt i could fabricate a matching tube with nice bends and welds. i looked at the top again this weekend. i think with some patience, i can get it thru. as for s/a and the war, i have no idea. i doubt we will do a thing, as iraq doesn't have the platforms and arsenal to take advantage of it. we'll just bomb away.

 

[karlp]

Re: gps question

Not exactly an answer to your question but a comment on GPS's. I bought a GPS in January and was torn between B/W or color. The salesman recommended color for daytime visibility at about twice the price so I bought a Garmin 182C (new flat screen technology) with the mapping chip. I bought it through the internet and saved $250. The performance and visibility is excellent and the mapping chip can't be beat. Accuracy generally is 15 feet and I can watch my route from the dock to my destinantion with all water depths clearly visible.