Geocaching
Many people think of “Blue Switch Day” (May 1, 2000) as the beginning of satellite usage for locating coordinates on the ground level. It actually had its beginning back as far as the early 1960s when US President Kennedy made public his desire to have the US reach the moon before the end of the decade. This sparked the development of a highly accurate satellite navigation system.
The US Navy launched this system in 1964, known as Transit and because of the tensions and competitive nature of relations with the Soviet Union they launched a similar system they called Tsikada. Both systems were two dimensional and highly accurate but took ten to fifteen minutes for the receivers of the day to process the information.
This system was fine for the navy as their travel was primarily by ships which were slow enough that processing speed wasn’t a huge factor. The Air Force, with the jet planes of the day, however had a different opinion and developed their own system as did the ground forces. In 1969 all these systems were combined to form NAVSTAR GPS. At this time there was still no recreational aspect in consideration for the system.
This system was used until the late 1970s. In 1978 the first Global Positional System satellite was launched but it wasn’t until another six years had passed that civilian use was allowed on the system. At that time, because of Selective Availability, (intentional time varying errors of up to 100 meters (328 ft) to the publicly available navigation signals) it was not all that useful for precision work. This was intended to deny an enemy the use of civilian GPS receivers for precision weapon guidance. This meant that the accuracy still wouldn’t be good enough to find a nano in a steel handrail, but you could possibly find one of the huge Zoo type hides in a well mowed open field. Without a classified seed key to unlock the system, recreational use was out although products for civilian consumers began showing up in stores.
Once all twenty four satellites were in place around 12,500 miles above the earth, GPS receivers could lock onto at least four signals and now determine coordinates in three dimensions. They circled the earth every twelve hours on six orbital planes.
About this time the Soviets, not wanting to fall behind, developed new technology of their own. This new system was and still is known as GLONASS. It also has twenty four satellites but travels on only three orbital planes.
Today, you can receive signals from satellites belonging to both of these systems as well as those from China, India, Japan, and the European Union. If you wish to see where in our sky these are download an app for your phone for that purpose. I use an APP called GPS Test.
In 1996 President Clinton decided that the US should open the GPS system to the public and it happened on May 1st 2000. Literally, a switch was flipped which turned off the Selective Availability and portable GPS units became accurate within five to ten meters.
About this time an electronics and software engineer named Dave Ulmer from Portland, Oregon stayed up late the night that blue switch was turned off to see if the accuracy of his personal GPS receiver would improve. It dawned on him that this was something that could have other uses now and he came up with the idea of a treasure hunt. After practising with his GPS receiver he placed a five gallon bucket with a logbook and some small treasures near a wooded road about a mile from his home.
He posted a message on a Usenet newsgroup about “The Great American GPS Stash hunt” on May 3, 2000, about his idea and on May 5, he posted the coordinates and encouraged others to do the same. In less than five days there were stashes from California to Illinois and all the way to Australia.
Soon after there was discussion about the name “stash” as it was close to terminology used in the drug trade. Geocaching was born. A mail list was formed on eGroups (which is now Yahoo) to share ideas and locales. By September this was replaced by a website with the address of www.geocaching.com which is still the primary site to use for caching.
Originally a GPS receiver was needed for the sport but now anyone with a cell phone can go hunting as well. A GPS unit can get you within two meters as can a better smartphone. Most phones are good for as close as three meters though. A GPS on the L5 band can actually get you within twelve inches of ground zero, but remember that if it was placed by someone with a regular cell phone it is still possible for it to be out by three meters no matter how good your unit is.
Whatever type of receiver you use I hope to bump into you searching for a cache somewhere out on the trails.
Gary Brown is the President of the Manitoba Geocaching Association (MBGA) and can be reached at
[email protected].
