Anybody seen last Saturday 9am Discovery Channel's "How do they do it" episode? One of the featured topics was about GPS mapping. A brief background about GPS and satellites was discussed. They said there are currently 30 satellites for GPS use in orbit and billions of users access these satellites (i'm one of those billions 
). The satellites are maintained and controlled by the Colorado Control Station located at the Sterba Airforce Base. Every year, a satellite is repositioned in order for it to maintain an accurate orbit. For navigation, we need at least 4 satellites to calculate our position and our receivers work out where we are by calculating how long a satellite signal arrives in our GPS, then measuring the distances to the sats. They said that on-board atomic clocks are used in our GPS for greater time accuracy as an error of a billionth of a second translates to a 1km locational error on the ground.
There's this part of the program that shows two commuters travelling from a place in the US to Chicago to attend a party. One uses paper maps while the other uses a GPS to navigate. Travel time would take 11 hrs. through unfamilar places. The one using a GPS arrived with time to spare, while the one with the paper map kept getting lost, hehe.
They then featured a mapmaker - Tele Atlas. They have a mobile mapping team that updates the map. They have 24 mobile unit vans that go around the US travelling at an average of 150-300 miles/day/van. Each van is equipped with 8 cameras that take pictures of POIs, street markers/names, landmarks & etc. They also have 2 onboard lasers that measure the road widths and marks the POIs. These vans get a mileage of about a million miles a year just updating the Tele Atlas maps.
They also showed an actress from the Netherlands with an exceptional voice quality and clarity whose voice was used in Tomtom's GPS devices. She was made to read phrases which were then cut and arranged so you get to hear the appropriate phrase in your GPS when navigating.
Overall it was a very informative show. And looking at how we do our mapping, i'd say we're doing it the primitive way. Which is understandble and acceptable as we do it for free, in the spirit of bayanihan 
. However, we can learn a thing or two on how they do it. For example, it would be a good practice to bring a digital camera when marking POIs or recording street name signboards. If you sync you're camera's time with your GPS, you would be able to tell where you took a pic of that POI based on the pic's time stamp (much better if your digicam has the geotag feature). This can be done in Mapsource where you get to see the time stamp of every point in your recorded track. Or you can use a voice recorder to describe a POI or record a street name.
I'm sure they'll replay that episode again... hope i can watch the replay so i can get more details...
). The satellites are maintained and controlled by the Colorado Control Station located at the Sterba Airforce Base. Every year, a satellite is repositioned in order for it to maintain an accurate orbit. For navigation, we need at least 4 satellites to calculate our position and our receivers work out where we are by calculating how long a satellite signal arrives in our GPS, then measuring the distances to the sats. They said that on-board atomic clocks are used in our GPS for greater time accuracy as an error of a billionth of a second translates to a 1km locational error on the ground. There's this part of the program that shows two commuters travelling from a place in the US to Chicago to attend a party. One uses paper maps while the other uses a GPS to navigate. Travel time would take 11 hrs. through unfamilar places. The one using a GPS arrived with time to spare, while the one with the paper map kept getting lost, hehe.
They then featured a mapmaker - Tele Atlas. They have a mobile mapping team that updates the map. They have 24 mobile unit vans that go around the US travelling at an average of 150-300 miles/day/van. Each van is equipped with 8 cameras that take pictures of POIs, street markers/names, landmarks & etc. They also have 2 onboard lasers that measure the road widths and marks the POIs. These vans get a mileage of about a million miles a year just updating the Tele Atlas maps.
They also showed an actress from the Netherlands with an exceptional voice quality and clarity whose voice was used in Tomtom's GPS devices. She was made to read phrases which were then cut and arranged so you get to hear the appropriate phrase in your GPS when navigating.
Overall it was a very informative show. And looking at how we do our mapping, i'd say we're doing it the primitive way
. Which is understandble and acceptable as we do it for free, in the spirit of bayanihan . However, we can learn a thing or two on how they do it. For example, it would be a good practice to bring a digital camera when marking POIs or recording street name signboards. If you sync you're camera's time with your GPS, you would be able to tell where you took a pic of that POI based on the pic's time stamp (much better if your digicam has the geotag feature). This can be done in Mapsource where you get to see the time stamp of every point in your recorded track. Or you can use a voice recorder to describe a POI or record a street name.I'm sure they'll replay that episode again... hope i can watch the replay so i can get more details...
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