TeamRJJO

Our "signature" items are rare recordings of live shows by various artists. I have apretty large collection of live recordings from Rush, Genesis, U2, Pink Floyd, The Who, Grateful Dead, etc, etc. This seemed the perfect way to spread the music and marry two hobbies. For those in Northern VA, I just placed a copy of U2 in Seattle on 4/24/05 in the "Spider-Man's Newington Adventure" cache. It's waiting for someone to give it a good home..... I also second the recommendation to visit archive.org. I have literally d/l'ed hundreds of Grateful Dead shows from that site. Peace, TeamRJJO

USAF 1990-95 (Active duty) 2 SOPS, Schriever AFB, CO Payload analyst in the squadron that operates the GPS constellation.

We are relatively new at geocaching and live in the DC/Northern Virginia area. Are there any local Geocaching organizations or clubs? Are there any gatherings or events planned in this area? Thanks

Here's a link that explains it much better than I can: http://www.geo.ucalgary.ca/~wu/TUDelft/Rot...r%20wander' Peace, TeamRJJO

The range measurements used to generate orbit models of the sattelites are taken in Earth-centered-Earth-fixed coordinates. When the navigation message is constructed, a coordinate transformation to a Keplerian element set is performed. In order to be able to accurately transform the Keplerian elements back into a form usable by your GPSr, the elements must be adjusted for polar wander. This gets done in the navigation message so that the user doesn't need to bother with it. Peace, TeamRJJO

The parameters in the navigation message broadcast by the satellites compensate for polar wander. Polar wander estimates are updated in the GPS Master Control Station once a week. This is completely independent of receiver firmware, by design. Peace, TeamRJJO

Dunno about this. This was an episode of "Mythbusters" a few months ago, and they had to REALLY try hard to generate a spark that would ignite gas fumes. They weren't able to generate a spark with a cell phone, either. At one point, they interviewed a guy from whatever government agency mandates those signs at the gas pumps, and he basically said the whole thing was an urban myth. Peace, TeamRJJO

It really depends on where you live. At higher latitudes -- for example, most parts of the USA and northwards, you will rarely see 14 satellites. If you live close to the equator, a 14-channel receiver may actually be useful. Peace, TeamRJJO

Hey all, I used to be a GPS payload analyst in the 2 SOPS, the Air Force unit that operates the GPS constellation. In a nutshell, the navigation data uploaded to the satellites daily does indeed account for variance in Earth rotation. This variance is irregular, and impossible to predict with complete accuracy, as it does arise from sources such as wind, atmospheric friction, etc. But NGA provides observation of UT-UT1 to the 2 SOPS each week. These observations are used to generate predictions of rotational variance and polar wander. These predictions are in turn used in the coordinate transformation that takes place each time a navigation upload is generated. The tsunami did indeed have an effect on Earth rotation, but the effect was minute, and would already be absorbed into GPS predictions. If the error WAS ever big enough for us to see, it would have occurred in the time between when the tsunami occured and the satellites were uploaded with a fresh navigation message. In all likelihood, only someone heavily post-processing GPS data would notice any perturbation. Peace, TeamRJJO

We are relatively new to geocaching and are using the Garmin 12CX and are having trouble with spotty reception in some places (probably normal due to tree cover and satellite position). We are wondering if we buy an additional, less expensive unit if it would help our hunting. If so, is there an inexpensive unit you would recommend? Right now, we are using mapping software on our computer and do not necessarily have a need for that on our unit.