A GPS can now not just tell you where you are and how to get where you want to go, but it can also give you other information tailored to where you currently are.

The first Location Based Service (LBS) was traffic information.  New services now promise to tell you where the cheapest gas can be purchased nearby, give you weather forecasts, tell you what's showing at local theatres, offer discount coupons for nearby stores, and who knows what else.

GPS and Location Based Services Making your GPS enormously more useful
	A GPS unit - already amazingly clever for knowing exactly where you are, anywhere on earth, can now start to tell you information about other things around you, too. Part of our series on GPS - additional articles to be published in coming weeks - see links on the right.

Location based services (LBS) marks the new frontier of GPS type services, whereby you are given information about things close to you, based on where you are at any given time.

In theory, the best LBS requires bi-directional communication between your unit and the central data server - your unit tells the central server where it is and what it wants to know, and the central server sends that specific information to your unit.  This is possible if your GPS receiver is combined with a cell phone with data service, for example.

Normal GPS units don't offer bi-directional data services, but work-around location based services still exist for them.  These services broadcast data for a wider area and the GPS, based on its knowledge of where it is, selectively filters and only shows you the relevant local information.

In theory, this can enormously increase the usefulness of your GPS.  In reality, the services tend to be sketchy, incomplete, and not always reliable, although they are improving rapidly and soon will be ready for prime time.

Adding More Value to GPS

Imagine a GPS that doesn't just tell you where you are and how to get where you want to be, but which also knows if roads are congested or not and chooses your route based on congestion as well as distance and road type.

Imagine a GPS that does double duty as a reference guide, telling you information about the area where you are, including where to buy the cheapest gas, and what is showing at nearby theatres (and how to get to the gas stations and theatres if you're unfamiliar with their location).

These capabilities are starting to appear in GPS units now.  The theory and promise of these types of added value services currently exceed the reality and practicality, but with each passing month, these services are becoming more reliable and comprehensive.

With several different companies involved in publishing this data to GPS units (and to mobile phones) the field of 'location based services' is one of the most rapidly growing and evolving parts of GPS related services.

LBS capabilities are currently only available on top end GPS units, but expect them to quickly migrate down to middle priced units during the next 6 - 12 months, and down to lower priced units shortly after that.

Different types of GPS Data Services

There are several different ways that location data can be broadcast to GPS units.  Most of the time, the method being used doesn't really matter to you, because it is pretty much automatically integrated into the GPS receiver you have.

Some GPS manufacturers are 'playing the field' - for example, Garmin has units that will receive XM Radio data service, MSN Direct service, and also Clearchannel TMC service.  Clearly there is no clear 'winner' for best service at present, but this can be expected to change as differences start to appear between the services, and what were, only a year or two back, very rudimentary and generally disappointing services start to become more fully featured and useful.

Currently two methods are being used, and a third is being developed.

• Satellite transmission :  Both XM Radio and Sirius have traffic data services (and both provided by the same company) that can be sent to compatible GPS receivers.  This data covers the entire country, and your GPS then filters out just the relevant regional data.

• FM Sideband communication :  This uses either the 'RDS' service (used by Clearchannel and Navteq RDS) or a similar means of piggybacking a ride on an FM signal (used by MSN Direct).  These services have very low bandwidth (less than 50 bits/second of data) but only have to broadcast for the local area.
  
  This is almost too slow, and it means if you drive into a new area, it might take you an hour or more before all the latest information has been received by your unit.  If you're driving fairly fast, you could conceivably be driving faster than information can get transferred to your unit, making the service almost useless.

• HD Radio :  The new HD Radio technology offers the potential to add much greater bandwidth for data transmission, but to date there are not many HD Radio transmitters out there, so there are no services using this technology yet.  As HD Radio becomes more popular, look for HD Radio based services to appear.

In addition to this broadcast type technology, there is also the potential for interactive narrowcast technology, typically via a cell phone's GPRS data channel.  In such cases, the GPS can communicate, via the attached cell phone's data link, to the traffic data server and request specific data for exactly where the GPS is and where it will be going.

Where the Data comes from

Any of these services are only as good as the underlying data they are sending to your GPS.

There are three major sources of data.  The first is the data provided by state and local departments of transportation.  This data is generally obtained by sensors in the roads that detect vehicles passing over the top, and with a bit of extrapolation, it is possible to work out traffic speeds and density.

This data is usually reliable, but the sensors sometimes fail, and prior to failure, can start generating erroneous data.  And this data is also typically limited to the main freeways and highways in the major metropolitan areas.  It provides an excellent base however.

Some services overlay extra data on top of this basic raw data.  Some will add incident data - information on road works and traffic accidents.

And then there is Inrix.  This company has a very clever concept - it receives data feeds from some 650,000 different vehicles on the roads that are fitted with bi-directional GPS tracking devices.  These are typically delivery vehicles, taxis, and other such commercial vehicles.

Using the data received from these vehicles (typically location, direction of travel, and speed), Inrix knows the reality of how fast traffic is moving.  This data is not limited only to major freeways, it can be obtained from anywhere that the vehicles reporting back to Inrix are traveling, and indeed Inrix now claims to have traffic information on over one million miles of US highway (not all of which is being realtime updated all the time).

The Inrix model - a collation of DoT data and the information from vehicles actually driving on the roads - represents the high point of traffic data at the present.

Inrix data is incorporated into the Clearchannel service, and is also used with Tomtom units that connect to a phone via Bluetooth and then through the phone's data service.

Inrix also make their own software that can work on most Windows Mobile phones, Inrix Traffic for Windows Mobile.  This doesn't require a GPS receiver, and simply provides traffic data for the area you specify.

Some mobile phone companies are looking at adding this data to their mobile phones as well - for example, Sprint is adding a Telenav product option to their phones, and Telmap will soon be offering a service that runs on a range of different mobile phones.

What Sort of Data You Receive

All the services provide some type of realtime traffic reporting, advising you of traffic congestion, accidents, road works, and other things that might impact on your driving.  Depending on where the services obtain this data depends on how accurate and helpful it is.

In addition to traffic information, MSN Direct distinguishes itself from all other services currently by providing three other types of information :

Weather :  You are advised of the current conditions where you are and offered a three day forecast.  In addition, information on other nearby localities is also provided, both current conditions and three day forecasts.  The forecast in particular can be useful - if you are planning an activity for a day or two or three in the future, you can glance at the forecast to see what type of weather is likely.

Movies :  You can see what is playing at nearby theatres and when, plus you can navigate to the theatre if you're not sure where it is.  This is helpful and generally the information seems to be fairly complete.

Gas Prices :  Leaving the best for last, this is a wonderful feature.  Gas prices charged at nearby gas stations are displayed, along with information about when the price was last updated.  If you're driving down the freeway and need to buy gas, you now know where the cheapest gas is likely to be.  With a spread of sometimes as much as 15c a gallon between cheapest and most expensive gas station in the vicinity, and with say a 20 gallon fill, you can save yourself $3 per fill - not a great deal, but a small victory, and the pleasure of knowing you are shopping strategically for gas is reward in itself.

Not all gas stations participate in this service.  In my area, I'd estimate that perhaps 90% of stations participate, however, so the coverage is thorough if not 100% complete.

Service Cost

You'll pay for any of these data services, although MSN Direct offers a $130 flat single fee for the lifetime of the device you're registering with them.

Other services cost $60/year (Clearchannel) or more.  XM Radio's NavTraffic service, for example, costs $9.95 a month as a standalone service, or an extra $3.99/month if you already subscribe to XM's regular radio service.

MSN Direct seems to currently have the lowest price and the best features, and with their gas price information, they become the only service that promises to save you money as well as offer you helpful data.  As such, it seems to be the best choice, albeit one which only works with very few GPS receivers at present.

Overall Inadequacies

The biggest problem with most of these data broadcasting services is they lack sufficient bandwidth to get the information you need to you in a timely manner.  Due to the very narrow bandwidth, information providers have to compromise, either by only sending you very limited data (ie traffic data only) or alternatively by sending you a broader range of data but which takes a long time to update as you move from one area to another (ie MSN Direct's service).

The future of these services clearly lies in GPS units being able to interactively converse with an information service provider and request specific data and get only that data sent to them.  This probably requires the unit to 'borrow' some of the data service available through your mobile phone.  Until then, the other types of location based services currently on offer with GPS units represent disappointing compromises.

Read more in the GPS articles series

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Originally published 29 June 2007, last update 21 Jul 2020

You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.