So how do GPS guided tours work? We often get this question so we're hoping this will provide you with a better understanding of how our systems work.

Many people have had the opportunity to interact with GPS, whether it be on a mobile phone, satellite radio, a PND (a Personal Navigation Device such as a Garmin or TomTom GPS for your car) or on one of our tours while listening to the automated GPS triggering of pre-recorded tour commentaries.

We often get the question - How do you stream audio from satellites? This is how satellite radio for a car works. The short answer is – we don’t stream audio from satellites.

We use a GPS receiver that receives Global Positioning System (GPS) signals for the purpose of determining the location of a bus, boat, trolley, train or tram while out on a tour.

Wikipedia defines the Basic Concept of GPS as:

“A GPS receiver calculates its position by precisely timing the signals sent by the GPS satellites high above the Earth. Each satellite continually transmits messages containing the time the message was sent, precise orbital information (the ephemeris), and the general system health and rough orbits of all GPS satellites (the almanac). The receiver measures the transit time of each message and computes the distance to each satellite. Geometric trilateration is used to combine these distances with the location of the satellites to determine the receiver’s location.”

The location of a vehicle or vessel on our GPS guided tours is determined by using this data which includes the direction, speed, latitude and longitude calculated from vehicle or vessel position changes every one second.

The direction of a vehicle or vessel is determined by collecting two points of data one second apart. The use of directional GPS triggers is often essential for overlapping routes. Another example of why a directional trigger may be necessary is as follows:

While working with Kingston Thousand Island Cruises, we needed to provide directional triggering for their tour boat operation. Here's why.

The first segment of commentary is triggered by GPS right off the dock. To eliminate any issues with this GPS waypoint triggering again when tour boats return to the dock, this first GPS trigger is directional. Tour boats returning to the dock will not trigger the initial commentary since they are moving through the GPS waypoint from a different direction.

Audio commentaries are played when the precise location of a vehicle or vessel enters a GPS waypoint. Our GPS waypoints are created as zones – (circles) or by longitude or latitude exclusively. The size of the “zone” or circle depends on the application and its intended purpose. We can make GPS waypoints as small as 2 metres (there is no practical application for this) or as large as a football stadium (or even larger).

To accomplish this, we use GPS route building software to build our GPS play lists. This software is initially used to collect GPS data in the field. By connecting a GPS receiver to a laptop we get real-time satellite data on our current location. This data includes direction, latitude, and longitude information.

We collect this information precisely where we want to deliver audio, video, or multimedia content. By placing a GPS receiver on top of a car or a van (or a train or a boat) we collect the GPS waypoint data on the routes themselves. We determine the best locations for stories – working closely with our customers to achieve their goals for location based storytelling.

When we're collecting GPS coordinates, we're already determining whether or not direction is required, tolerance (the size of our GPS zones) as well as the available storytelling time our writers have between GPS waypoints. Traffic conditions are also taken into consideration (on land and the water).

For example, we developed a new play list command for the boat tour market – GPS triggering content by latitude or longitude exclusively (and by direction if necessary), removing the issue of boats having to weave through water traffic to get to a GPS waypoint. Now vessels can make the necessary course changes due to heavy water traffic and still cross the latitude or longitude line to begin the next segment of commentary on their sightseeing tour.

The play list and its associated commentary is stored on media cards (much like the media cards you insert into your digital camera). With content being stored on media cards, there are no moving parts inside the GPS Tour System that can be compromised by vibrations.

When our GPS tour systems enter a waypoint, commentary automatically plays in one language – or several simultaneously. Based on the data our systems receive – (latitude, longitude, direction, and speed), our GPS play list directs our GPS tour systems to search for and play the associated segments of commentary. For example, in a single language GPS tour application, our GPS play list will command the GPS tour system to:

Play mp3 file number 10 when this bus enters our GPS zone at latitude 40.764750 and longitude -73.984258. When the bus enters this zone, it automatically plays segment number 10 on a Public Address system or to wireless receivers and headsets.