USB GPS Recommendations?

[dmdelorme]

I would use any cheap usb gps puck if your boat is fiberglass and no core you can bury it out of site. I would not spend big bucks or use Bluetooth. The dedicated marine ones are a ripoff. mt333X are good chips. You need 3 sats for 2d and 4 for 3d any more allows the gps to pick a better consolation faster remember the max procession is 3 meters regardless of the bull they try to feed you. That is the limit for non RTK grade GPS. If you want to test your boat for use you phone to test the spot you want to put your GPS if the signal is too weak you might have metal or water blocking the signal wood will block the signal as it contains moisture. depending on where you sail you might want one that can use other GPS sat systems. It takes a GPS a while to get a fix if it has been off a long time or it has been moved a distance from last use. it take a bit to download the new constellation data. Some have the ability to download new data to the unit via internet for a faster first start.
Here is a bit of text to explain:


It may seem slightly counter-intuitive, but in order for a GPS unit to produce an accurate fix, it has to know the time, the location of the GPS satellites, and it's own rough location. Odd, given that it's job is to tell YOU those things. Since the satellites broadcast the time and their positions, the GPS unit can get the info but it must have a strong signal (>25dBHz) from 4 satellites for about a minute. If the signal level drops a little or a satellite goes out of view in that minute, the GPS unit has to start over again. Outdoors with a clear view of the sky, this isn't usually a problem. Indoors or when the outdoor view is obstructed by trees, terrain, buildings, etc. it can be impossible to get an initial fix because you just can't get a strong signal from the same 4 satellites for enough time.
"But wait, my cell phone gets a fast fix indoors!". Yep, and there's a reason for that. Being network connected, the phone already knows the exact time and it's rough location as the cell network provides both. As for the location of the satellites at any particular time (the ephemeris data), that's public information and the GPS manufacturers thoughtfully provide files, usually updated nightly and good for 7, 14 or 30 days, that the phone can download. The whole process is called Assisted-GPS and doesn't require as strong a signal (~15dBHz) to get and maintain a fix.

[Cpt Balu]

Ok so also the cheap once will work in the South Pacific

[rgleason]

If you don't want Globalsat, look into U-blox it seems to be very popular and supports many GPS sats.

[Moo]

Originally Posted by Cpt Balu

Ok so also the cheap once will work in the South Pacific

Yea and everywhere else on the planet.

[a64pilot]

Originally Posted by Moo

Yea and everywhere else on the planet.

Not to be cute, but if your going way far North as in well above the Arctic circle, it’s takes a good receiver to work well, and even the good receivers, like Garmin Aviation handhelds lose significant accuracy, it seems the far North isn’t covered as well.

[Pizzazz]

Originally Posted by rgleason

If you don't want Globalsat, look into U-blox it seems to be very popular and supports many GPS sats.

I second the u-blox suggestion. It costs $11.99, has WAAS correction, nmea output, works with all constellations and obtains a fix in 30 seconds, upside down in the bilge.

SV Pizzazz

[rgleason]

SV Pizzazz .. fix in 30 seconds, upside down in the bilge.



What? Not really!