gurubob

Leica is the best... Have you ever heard of a little navigation company out of Sunny Vale California? Trimble is in my opinion the finest GPS survey equipment maker to walk the face of the earth. In short... a minimum of 5 satellite vehicles(SAVS) transmit a series of coded frequencies L1, L2 & P (most common in private and military applications). A receiver like the car radio reads these signals and establishes its position. Static Surveys can require observations up to 2 hours. Faststatic does the same thing in about 7 minutes. since selective availibility was turned off even hand held consumer models can determine position to very accurate levels. RTK lets this assumed point act as a transit for radial collection and staking. A rover(second receiver) reads the SAVS signals and a radio link between the two receivers allows them to "talk" to each other establishing a relative position. The rest is math.

I know geocaching is an exciting sport/hobbie. It is world wide and has many fans. Would I say geocachers are the general public... NO. Although, very curious and assuming, the response I've recieved from this posting have been very mixed. In general the response has been negative. These benchmarks are not toys and I don't begin to assume that geocachers are out searching them down to destroy them. However, activity around benchmarks leads to curious minds wandering on top of them. People without the first hand knowledege of the importance of these points see only an old disc thing that would be cool in a private collection. I would also like to point out that the subject of preserving benchmarks and/or destroying them for personal gain had not been addressed in forum. Sorry but, I want it to be known that willful destruction of these valuble survey markers happens. The more everyone is aware of this fact the more everyone can help to prevent destruction. ICBM... I think some of you may understand why publishing(Internet)coordinates to these points could possibly be a threat to National Security.

Back when... the DOE created a GPS network here in the fine county of Ellis. This survey established control for the Superconducting Super Collider SSC. It includes approximatly 300 first order vertical and horizontal monuments. I have been to the majority of these monuments. They are the cool new ones. Extruded aluminum canisters with hinged lids over 8' 1" steel rods driven to the point of refusal. The rods are incased in a hydrolic fluid stasus. Built to last. To bad the SSC wasn't built to last. Same local datum and projection used by published NGS monuments (NAD 83 NORTH CENTRAL TEXAS 4202). This is a very sweet network. I would like to know, have you ever found DOE monumentation and are the monuments typical?

A Nationaly distributed publication... written by writers... reviewed by editors. I don't think POB intended to insult anyone when the published it. I din't mean to insult anyone. I found a good answer to a hard question to answer.

Metal Detector

I posted this POB article to answer a friends question. I thought the little picture of the printed paper with a thumb tack would make that clear. This is a description of a survey control network that would be suitable to establish NGS monumentation.

once new and existing monument locations are finalized, existing NGS HARN stations and bench marks are selected as project control. Control is selected in a configuration optimized for both horizontal and vertical support of the GPS network(s) and in accordance with the FGCC guidlines with sufficient redundancy to allow for quality control evaluation and blunder detection. at least one GPS session baseline should be directly observed between each station azimuth pair. this results in uniform coordinate quality on all survey stations, an overall stronger GPS network and fewer total GPS observations. when existing NGS bench marks can not be directly occupied, a temporary eccentric point should be set at a nearby inhabitable location. conventional differential leveling techniques can be used to transfer an elevation from the bench mark to the eccentric point.

I hope people will respect the fact that these elevated and tri points are working tools important to survey and engineering projects. I am a surveyor and there is nothing I hate more than searching for a bench only to find some idiot has destroyed it because it would look cool on his mantle. Hundreds upon hundreds of men spent hours, days, weeks, months and years establishing these reference points. I understand that these points have been published as a matter of public record but, I don't thik it was intended for this use. When you need flood plain certification or the new store in your town needs to prove its pad above flood elevations I use these very important tools to prove it. If I have to spend hours searching for a refference point so you can get flood insurance you will have to pay for it. If I have to use a different point to establish coordinate geomertry to locate your house for your title you will have to pay for it. Please keep this in mind. Protect our benches.