I have a http://www.madmanmarine.com/ wifi unit that takes output from my NMEA concentrator then make is available via serial/usb, tcp/ip or UDB.
I have a chartplotter and GPS in the system and can get the info on iRegatta or PolarNav on Mac. Also tested with some free/cheap windows programs. I have an iPad 1.0 that still runs some chartplotting software and has built in GPS. It is on my boat right now and I can find it via iCloud. Useful as we are having some dicy weather in the North East this weekend. At least I can tell if the boat is still on its mooring. On Fri, Oct 2, 2015 at 6:04 PM, Jerome Tauber via CnC-List < cnc-list@cnc-list.com> wrote: > It works well below deck when you are in cell range. How does it work > below deck with just a GPS signal offshore? I don't want to belabor the > point. Jerry > > Sent from my iPhone > > On Oct 2, 2015, at 4:36 PM, Graham Collins via CnC-List < > cnc-list@cnc-list.com> wrote: > > Hi Jerome > I must disagree with that statement. My sony tablet with built in GPS > works perfectly below decks, it is what I use for anchor watch. > > Graham Collins > Secret Plans > C&C 35-III #11 > > On 2015-10-02 12:42 PM, Jerome Tauber via CnC-List wrote: > > Joe - that is a common misunderstanding. While the Iphone does not need > cell service for positioning it actually does use cell tower triangulation > for position and is not very accurate or fast without it. Moreover, if > you are below deck you will not get an adequate GPS signal. This is from > the internet. > MotionX-GPS Does MotionX-GPS require a cellular network? > The iPhone 5, 4S, 4, 3GS and 3G use an A-GPS (Assisted-GPS) chipset which > uses cell tower triangulation to speed up GPS signal acquisition. Cellular > coverage is not needed to acquire a signal, however the signal acquisition > will be much quicker if you have data coverage. > Without data services, it can take 15 minutes or longer to acquire a > signal. This is simply because it takes longer to determine which > satellites to use out of the 31 available around the world. With data > services, it typically takes under a minute, but it can take up to 5 > minutes. > > How the iPhone knows where you are > By Glenn Fleishman <http://www.macworld.com/author/Glenn-Fleishman/>, > Macworld > iPhone users' experience with GPS is so quick, so instant-on, that Apple's > Wednesday > response about location tracking on iOS > <http://www.macworld.com/article/159501/2011/04/apple_location_data_response.html> > might almost seem baffling: > > Calculating a phone’s location using just GPS satellite data can take up > to several minutes. iPhone can reduce this time to just a few seconds by > using Wi-Fi hotspot and cell tower data to quickly find GPS satellites. > > Several minutes? Doesn't my iPhone take just seconds to figure out where I > am? > Well, yes… but only when it engages in a set of tricks to avoid a lengthy > process that was de rigueur when GPS receivers first appeared. In > simplifying matters, Apple’s not being entirely accurate about how this all > works and what it's doing. So let me explain where Wi-Fi and cell phone > towers fit into the equation. > 12.5 minutes to locate > Early GPS receivers took 12.5 minutes from a cold start to obtain a lock; > later locks in the same region could still take minutes. If you turned a > GPS receiver off for a few weeks or moved it more than a few hundred miles, > a cold start might be required again. > GPS relies on two factors to create a set of accurate coordinates for > where you’re standing: time and space. GPS satellites broadcast precise > time signals using a built-in atomic clock along with their current > location. They also broadcast the location of all other satellites in the > sky, called the almanac. > Every 30 seconds, a GPS satellite broadcasts a time stamp, its current > location and some less precise location information for other GPS > satellites. It takes 25 of these broadcasts (thus, 12.5 minutes) to obtain > the full list of satellite locations. This information has to be decoded > for a receiver to then properly interpret signals from the satellites that > are within range. > If you know the position of four satellites and the time at which each > sent their position information, you—or, rather, your GPS receiver—can > calculate to within 10 meters the latitude, longitude, and elevation of > your current location along with the exact current time. With three > satellites, you lose elevation, but a device can still track movement > fairly accurately. Standalone GPS receivers can lock in simultaneously on > multiple satellites, and track more than four. Other techniques can improve > accuracy, too. > But, heck, I don’t have 12.5 minutes. I’m a busy man! Give me that > location faster! > Giving GPS an assist > So GPS chip and gear makers came up with a host of ways to shorten the > wait, called Assisted GPS (AGPS). Instead of relying on live downloads of > position data from satellites, future locations can be estimated accurately > enough to figure out rough satellite positions, and get a fix at which > point even more up-to-date information is retrieved. These estimates can be > downloaded via a network connection in seconds or even calculated right on > a device. > The current time can also be used as a clue. With a precise current time, > fragmentary satellite data can be decoded to gain a faster lock or figure > out the appropriate information to use. In CDMA networks, such as that used > by Verizon, GPS-synchronized atomic time is required for the network’s > basic operations, making it a simple matter to have such information > available. (In fact, CDMA cell towers have GPS units built in to maintain > better atomic time synchronization.)These extras are what makes GPS into > AGPS. Though a lot of people misunderstand AGPS and think it’s some faux > GPS system, that’s not the case: AGPS requires a GPS receiver to work. > Apple’s iPhone and 3G iPad models include AGPS, as do nearly all competing > devices with GPS chips, notably Android phones. (AGPS allows the use of > much cheaper and simpler GPS circuits in phones, reducing cost and battery > drain.) > > This is where Apple’s statement on Wednesday deviates from full accuracy. > Apple uses AGPS for native GPS-lock improvements, and Wi-Fi network and > cell tower locations are additional factors in providing a fast initial > connection along with improving GPS accuracy. > Cellular carriers have extremely precise GPS measurements of the locations > of all their towers. With a database of such towers, you can take > measurements of the signal strength of those within range—which may be > dozens—and trilaterate to find an area that overlaps among them. ( > Trilateration <http://en.wikipedia.org/wiki/Trilateration> involves > overlapping regions to find an intersecting area; triangulation uses the > measurement of angles to find a center point.) > But cell towers are too far away from one another to provide GPS-like > precision, and they don’t work well in less-populated areas, even suburbs, > where less coverage is necessary than in an urban environment. > > > _______________________________________________ > > Email address:CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the bottom > of page at:http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > >
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