I created this GPS website as a demonstration for the participants of the Internet Marketing in Action Workshop last week. As I was short of time and did not show them in detail how to do a mini-site with free web hosting, Netfirms.com. So I decided to to a new website on topic that I am familiar with.
Yes, I was involved with GPS land survey since the early 90’s. At the time, we could only get 4 or more satellites for less than 4 hours at a stretch. So planning before going out to collect GPS satellites data was mandatory. There were many times we spent hours collecting the data and then found out when we returned to the office that there were too many “cycle-slips” and the data was not reliable for further computation. Well, that was in the old days.
Why do we need 4 or more satellites?
I will not go into the technical details and complex mathematical formulae. Basically, we need signals from 4 or more satellites in order to eliminate the errors due to interference while to signals are propagated from more than 19,000km in the sky to the surface of the Earth. Remember, I was into land surveying and I needed centimeter accuracy.
Nowadays, with more than 24 satellites in operation, you get 4 or more satellites 24/7. Also, no “selective availability” to worry about. With a $100 handheld GPS, you can now get position to within 10m accuracy. And if you do a lot of long distance or inter-state driving, a GPS car navigator will be very useful.
An ex-colleague whom I spent numerous hours in the hot sun and tropical storm in Singapore trying to collect sufficient GPS satellites signals, called me a few weeks ago. He was telling me how amazing his new toy – a Garmin GPS for car navigation – gave him precise direction while driving around Singapore and when he travels to Malaysia in his BMW.
His phone call actually rekindled my interest in GPS. Not for land surveying though, but handheld GPS and car navigator units. I may even take up Geocaching as my new hobby.