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.
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
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
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
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
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
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
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
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
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
Some mobile phone companies
are looking at adding this data to their mobile phones as well -
for example, Sprint is adding a
product option to their phones, and
soon be offering a service that runs on a range of different
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
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
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.
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
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.
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
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
See the links at the
top right of the page to visit other articles
in our GPS series.
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29 June 2007, last update
21 Jul 2020
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