Archivo de la etiqueta: GPS

The Pillars of Navigating with your Phone

Mobile phones have become powerful devices over the years. There was a time when a mobile phone with GPS (Global Positioning System) was considered a high end phone but nowadays it is nearly the norm for most smartphones.

Here we will discuss the basics of using your trusted mobile phone for navigation, the rest you can find out by experimenting and experiencing it yourself.

There are people that have not unleashed the navigation capabilities of their mobile phones, but most city dwellers have come to rely on navigation applications such as Waze and lately Google Maps to navigate through the maze of streets in their cities. Obviously, to properly use those apps you will need an active network connection (mobile data service) which is not free or even included in most plans, at least not prepaid plans. If you have a mobile data plan then good for you! you typically need at least 1GB data allowance per month to moderately use your phone for navigation.

Some apps allow you to have offline maps that you can use for navigating even when you do not have a data connection but you will be limited to navigating through the bounds of that map. Keep in mind that keeping offline maps is going to consume some of your precious internal memory!

Our civil world divides the globe in four cardinal positions:

  • North or South for latitude, a number between -90 to +90
  • East or West for longitude, a number between -180 to +180

There are several ways to specify your location using these coordinates but they usually look like N 35° 57′ 48″  (latitude) W 79° 12′ 58″ (longitude). Military people use a different coordinate system which is basically another way for the same thing.

These coordinates can not only be used for navigating from A to B; there are worldwide games that make use of those coordinates to find “treasures” planted by other users, that is known as Geocaching and it is a very interesting way of putting that GPS to good use in addition to travelling on foot or on your vehicle.

What makes it possible?

There is something in most smartphones called the GPS which is basically a device embedded in your phone that makes use of as many GPS satellites to determine your position on earth. When buying your next smartphone make sure to check its specifications well if you wish to use it for navigation. While most will do it well enough, you can save yourself some surprises or frustrations by checking them against what we are going to describe below.

GPS Satellites

There are 27 GPS satellites orbiting our planet of which 24 are actively used and 3 for backup.

In theory your GPS only needs three (3) GPS satellites to be able to determine your position by a process called triangulation. This is very important because the more satellites your GPS can find in any given moment, the greater the resolution of your position. Typically only specialized apps give you the resolution information, it is not the same that your position be given with 100 meter accuracy than 3 meter accuracy. The lower the number (meters) the better.

The problem is that all of this depends on the “visibility” of these satellites. Your device’s reception of their signal can be affected by many things such as weather, trees, buildings, etc. Being outdoors is typically better but no guarantee.

You do not need mobile data to use the GPS device on your mobile phone because it senses those satellites orbiting out there in the skies. The GPS network of satellites circling the earth was originally deployed by US military instances but over the years as the system became available for civil use (with greater resolution that earlier), and now there are some civil GPS satellites out there.

Also, most mobile phones use a neat feature called geo-tagging which is basically attaching your GPS data (latitude and longitude). When enabled, when you take a picture with your smartphone, the coordinates or geographic location (latitude and longitude) get recorded on the picture as metadata which makes it great for later seeing on a map where a picture was taken. The problem is that if the GPS signal is weak, then this information is not available and thus not geo-tagged in a photo at least on a mobile phone. As an experiment we have taken pictures with GPS enabled while crossing the Atlantic ocean on a ship and no information was recorded. So your luck might vary.

GPS / GLONASS

If you have checked some mobile phone specifications and compared them you will quickly notice that while some say just “GPS” others say “GPS/GLONASS” and in this case the 2nd option is better!

GLONASS is basically another network of GPS satellites which has been deployed by the Russians offering comparative functionality.

So, what does it means having GLONASS support on your smartphone? It means that should the regular GPS coverage fail, you still have a whole network of GLONASS satellites available to you to determine your position on earth.

GPS / BDS

GPS (U.S.A.) and GLONASS (Russia) not enough? well there are already some smartphones with BDS support in their GPS circuitry.

But what is BDS? BDS or BeiDou (also known as Compass) is a Chinese initiative that started back in  2015 to build a global network of thirty five (35) global positioning satellites.

Well this is not common but we decided to mention it here for completeness and to avoid any confusing looks when finding “BDS” listed in the GPS section of the specs.

A-GPS

This is a method called Assisted GPS which is basically aiding your GPS device to get a quicker first indication (Time to First Fix) when it is difficult to get strong signals from the GPS satellites.

So what assists your GPS? Mobile communication towers, yes, you read right! Your Time to First Fix can be made quicker if you help your smartphone get the GPS information from the mobile towers of your carrier. Basically it uses the same method called triangulation so it will need data from three communication towers.

However, that you can establish a voice connection to the local carrier does not mean that you can get Assisted GPS, why? because in order to get the GPS satellite position from those communication towers you will need an active data connection. That is the reason why you can usually get a better GPS resolution when activating a data connection (cell data or WiFi).

If your mobile phone specification says it also has A-GPS then even better! the more the merrier!

Azimuth | Direction

It is great that you can locate your exact position on earth. In fact it can be fun to mention what your coordinates are. This is particularly useful if you are hiking!

But it is not only about determining your current place on earth. Usually you are also going somewhere and that means a direction.

For this the compass comes to our help and as most of you know the compass rose you usually see on maps not only marks the four cardinal points (North, South, East and West) but is also divided in 360 degrees. It means a great deal because it can be the difference between getting nearer to your destination than walking away from your destination! An error can get you lost.

So if you are moving it is useful to know in which direction you are moving which means your azimuth, for example you are walking heading 35° (thirty five degrees).

But some of you that have used Google Maps on your smartphone or some other specialized app for geocaching may have become very frustrated when noticing that when you made a turn the map did not!

While the GPS information can also give you an azimuth when moving, once you are not moving it has no way of telling you in which direction you are pointing your compass. Turn your body in a circle and it will not know whether you are seeing north, east or whatever!

Well, not all smartphones are made the same! believe it or not, even if your smartphone has GPS functionality it may not have a dedicated sensor called magnetometer or compass (seen in your mobile phone specifications). With this sensor in your smartphone you can use cool apps called Compass apps.

The magnetometer (compass) is not actually a magnet inside your phone; it is actually an solid state device called Hall Effect Switch that measures magnetic forces. It is used by your smartphone to measure the earth’s magnetic field and once calibrated be able to tell your azimuth pretty accurately even if you are not displacing yourself from A to B. For example, load a compass app and while standing in one place just turn your body around and you will see how it goes through the whole 0-360° range.

This little sensor makes it possible for your map to quickly rotate as you do when navigating because it can measure the earth’s magnetic field and therefore know where the North is. A word of caution though! since it is a magnetic sensor, it can be affected by magnetic fields (interference) created by electronic devices such as computers, monitors, etc.

So next time you go to buy a smartphone, make sure it also has a magnetometer in addition to a good GPS, preferably the whole thing (GPS, GLONASS, A-GPS).

What’s In The Box?

Sadly these days of information overload the sellers do not put sufficient information for a power user so you will probably have to get the smartphone full model number (factory model number, not its name) to find out which features it actually has (more on that in another post).

Unfortunately even the smartphone box usually contains just basic information that is not sufficient for an informed user, specially power users!

But if you have access to a fully working demonstration version of the Android phone you can use a neat trick to see if the phone has a magnetometer or other sensors.

  1. Open the Dial application of your phone
  2. Dial the following sequence:   *#0*#

This brings up a service menu unless it has been blocked by the manufacturer or the carrier (if you bought it from a carrier shop instead of an independent shop). One of those menu items is called “Sensors” and when you select it will give you real time information about what your smartphone sensors are measuring. In particular you would want to see there is a “Magnetic Sensor” listed and showing you information. Give it a try!

Ready to give Smartphone specs a look? then follow this link on GSM Arena to compare two smartphones, one with magnetometer and the other without.