Survey: Smartphone Charts

Electrical and electronic topics for small boats
L78steve
Posts: 13
Joined: Thu Aug 22, 2019 9:51 pm
Location: Hendersonville NC

Survey: Smartphone Charts

Postby L78steve » Thu Sep 19, 2019 9:46 am

Are you using the smart phone chart app?

I mainly navigate on the lakes of North and South Carolina and Lake Champlain. I just need to know where I am.
1988 15' Sport, 89 Johnson 70HP
1998 22' Progression Merc 300XP
1961 12' Allstar FG 73 Evinrude 25

jimh
Posts: 6905
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Survey:Smartphone Charts

Postby jimh » Thu Sep 26, 2019 10:40 pm

L78steve wrote:Are you using smart phone chart app?


For your survey: I am not using my cellular telephone for navigation charts.

rtk
Posts: 121
Joined: Fri Oct 16, 2015 7:06 am

Re: Survey: Smartphone Charts

Postby rtk » Fri Sep 27, 2019 8:02 am

I have (well had) a stand alone combination GPS/Sonar that I used on Lake Champlain. I also purchased the electronic chart for the areas that I frequented.

When I visited Lake George I played with I-Boating charts on my phone. There was some kind of subscription fee but it wasn't exorbitant considering the cost of marine electronic cartography. Give it a go see if you like it.

My biggest problem is seeing and using a phone based app for any purpose so after about 5 minutes I relied on a bit of dead reckoning using a paper tourist chart of the area. It had adequate chart data with regard to basic depth and navigation channel marker locations.

The phone typically gets shut off when I am on the boat. It's a great tool to have for this purpose, weather alerts etc but all the other stuff I can do without while I'm boating.

Rich

Jefecinco
Posts: 994
Joined: Fri Oct 09, 2015 6:35 pm
Location: Gulf Shores, AL

Re: Survey: Smartphone Charts

Postby Jefecinco » Fri Sep 27, 2019 10:13 am

Smart phone charts are simply too small to be of much use to me. Given the low cost of new MFDs I would always have one installed. Smart phone charts would be useful as an aid to get home if an MFD failed while using the boat.
Butch

jimh
Posts: 6905
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Survey: Smartphone Charts

Postby jimh » Fri Sep 27, 2019 2:27 pm

ASIDE: the GNSS receivers in smartphones used in the USA tend to use the GPS system and a feature called ASSISTED-GPS or A-GPS. These GNSS receivers depend on getting the navigation message from cellular data links provided by the cellular telephone carrier. These cellular providers are required by federal law to provide this service in order that a cellular telephone user can make a 9-1-1 emergency call and the 9-1-1 system can precisely locate their postion.

Once these smartphones are out of their service providers networks, they no longer get the navigation message data from cellular data. Without the use of A-GPS the performance of these receivers often is not as good as a dedicated GNSS receiver with its own well-positioned antenna. The position accuracy decreases, and the time to get a fix increases. These are further drawbacks to using a smartphone as a navigation device.

PatSea
Posts: 41
Joined: Sat Mar 11, 2017 4:52 pm

Re: Survey: Smartphone Charts

Postby PatSea » Sat Sep 28, 2019 10:06 am

Jim, are you saying the GPS in a smartphone is not a fully functional GPS as used in many other GPS assisted devices? Could you elaborate? I have used my smartphone for cruising in the middle of Lake Erie, well beyond cell signal coverage, and it performed well. Thanks.

Jefecinco
Posts: 994
Joined: Fri Oct 09, 2015 6:35 pm
Location: Gulf Shores, AL

Re: Survey: Smartphone Charts

Postby Jefecinco » Sat Sep 28, 2019 10:52 am

We recently purchased a smart phone. It was advertised as having "built-in" GPS. I interpreted that to mean the phone was equipped with a GPS chip providing decent position accuracy. So far, the accuracy while using the WAZE and Google Map applications seems to be very good ie. within a dozen or so feet. Our carrier is Consumer Cellular which, I believe, uses the T-Mobile networks. We have used the phone only in the Mobile, AL to Pensacola, FL corridors but plan a trip to Montgomery, AL soon.
Butch

jimh
Posts: 6905
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Survey: Smartphone Charts

Postby jimh » Sat Nov 09, 2019 2:11 pm

PatSea wrote:Jim, are you saying the GPS in a smartphone is not a fully functional GPS as used in many other GPS assisted devices?


PAT--I don't have a metric to use to judge your criterion of "fully functional" for a GPS receiver. Generally a GPS receiver has only one principal function: to deduce its location on earth from reception of the signals from GPS satellites.

I will restate what I said earlier about A-GPS:

The GPS receivers in many smartphones take advantage of very rapid time to first fix by using A-GPS. Some smartphones shut off the power to GPS chips when they are not needed. This can be done because a GPS receiver using A-GPS can have a very fast time to first fix from power-on, perhaps on the order of a second or two of time. This allows the smartphone to not waste battery life keeping the GPS running when it is not being used. My prior remarks described the A-GPS feature. Because A-GPS needs a very fast data connection to the cellular service provider, A-GPS functions are not available when no longer connected to a cellular network.

I don't know any details of how a particular smartphone works, but in general I would expect the people who design them are really smart. In the situation where there is no cellular data network available, the smartphone might be designed to just leave the GPS chip running all the time. While that will reduce battery life, it will help the GPS be able to maintain a position fix and not have to rely on Assisted-GPS to obtain the navigation message.

PatSea wrote:I have used my smartphone for cruising in the middle of Lake Erie, well beyond cell signal coverage, and it performed well.


Your account of a smartphone GPS getting a position fix when not connected to a cellular network does not conflict with my description of A-GPS. If you use a smartphone's GPS function, the GPS receiver remains powered on while it is in use. If you were to shut off a smartphone's cellular data connection, shut off the smartphone and let it sit for a week, then move it to the middle of Lake Erie, turn it on, and measure the time to get a fix, you would find that the GPS receiver in the smartphone would take at least a minute and perhaps much longer to get its initial position solution. That is inherent in all GPS receivers which are not assisted in receiving the navigation message via the cellular telephone network and the A-GPS protocol.

Comparing a smartphone to a dedicated GPS receiver for marine use also should be cognizant of the usually better positioning of the antennas in a dedicated receiver for seeing a clear view of the sky compared with a smartphone. GPS antennas in smartphones are generally inferior to the antennas used with dedicated GPS receivers because of their inclusion in the smartphone enclosure and close proximity to many other electrical devices. Because most of the time a smartphone is able to use A-GPS, the deficiency in their antennas is masked somewhat.

User avatar
Phil T
Posts: 1090
Joined: Thu Oct 22, 2015 6:08 pm
Location: Was Maine, now Kentucky
Contact:

Re: Survey: Smartphone Charts

Postby Phil T » Sun Nov 10, 2019 9:34 am

For reference:

---- Lake George, in NY is 32 miles long and 2 miles wide with a surface area of 45 square miles.
---- Lake Champlain is 107 miles long and 14 miles wide encompassing 514 square miles.

Given the severe limitation of cellular phones over water, the use of proper navigation devices (compass, charts, GPS) is the prudent way to go. A GPS plotter should be considered safety equipment, much like PFD's, flares and VHF.

There was a fatal marine accident in the UK recently in which one boat operator on a River was using an I-Pad app for navigation. Not a good outcome. While not exactly the same, you get my point.
Member since 2003
1992 Outrage 17, 1992 Evinrude 115

jimh
Posts: 6905
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Survey: Smartphone Charts

Postby jimh » Sun Nov 10, 2019 12:49 pm

In the most modern smartphones, the chips are no longer just GPS-only chips. The market for smartphones in global, and makers of smartphones now use chips that support many global navigation satellite system (GNSS) constellations. It is fairly common now to have some combination of GPS, GALILEO, and BEIDOU available, as well as WAAS, EGNOS, and QZSS augmentation systems in smartphones. In dedicated marine systems, GPS-only still seems to be the most common, but there are a few GPS and GALILEO or GLONASS receivers coming into use.

Here is a list of smartphones that use GALILEO: https://galileognss.eu/is-your-phone-using-galileo/

As you might expect, top-tier smartphones from Chinese maker Huawei now support BeiDou and QZSS augmentation, in addition to GPS and GALILEO, with WAAS and EGNOS augmentation.

shanejon
Posts: 1
Joined: Wed Nov 13, 2019 9:54 pm

Re: Survey: Smartphone Charts

Postby shanejon » Thu Nov 14, 2019 11:59 pm

L78steve wrote:Are you using the smart phone chart app?


Sometimes [the use of a smart phone chart app] depends on your telecom and the phone you are using.