http://javad.com/jgnss/javad/news/pr20151113.html
The advantages (or lack thereof) is what I felt a lot of one of the latest threads regarding the use of GNSS was about. Kent was advocating conventional ties. I was adding that short baselines (and multiple baselines) also had worthwhile advantages.
I am left wondering:
What is a Quick Fix? (1 second, 2 seconds, 5 seconds, 10 seconds, 20 seconds ...)
What is a short effective baseline (1/2 mile, mile, 2 miles, 4 miles, 6 miles, 10 miles ...)
Picture 4: (Short baseline with base under canopy vs. longer baseline with base in open) is not an obvious answer for me. Off the top of my head I would personally prefer a 2-mile baseline with my base in a wide open location than a 1/4 mile baseline to a base under canopy.
Most of the jobs that I am involved with are going to require 3 mile baselines if you put the base in the center. 3 miles is better than 30 miles, but is it good enough?
A Baseline consists of at least two control points. One base and one rover is not and never will be a Baseline.
As to Javad's comments on short GPS vectors is all true. That is why on short lines L1 is as good as and sometimes better than L1/L2.
Paul in PA
Paul in PA, post: 350105, member: 236 wrote: A Baseline consists of at least two control points. One base and one rover is not and never will be a Baseline.
According to Paul's dictionary, not mine.
"Baseline" is a well defined pairing of well controlled points. It has been an important element of surveying for quite a few years.
Somewhere along the line people started calling a GPS vector a "baseline" possibly in an attempt to imply what they do as more important. A GPS vector from a base is a one directional figure in three dimensions emanating from a single control point. I have seen many instances of using baseline in GPS explanations but to date have not seen an explanation of how it is a baseline. It is in fact not defined. It is equivalent to an observation of distance, plus horizontal and vertical angles from a total station. No matter how many observations to the same point are made that point is not perfected. I believe that Smoots are better defined than baseline.
A GPS vector is a line from a Base to a Rover, so why not call it a Roverline. Baseline is too important a word to be let to degenerate to also mean a much lesser figure or feature.
Does everyone who has accepted baseline to be understood because they felt uninclined to question others using the word without explaining it also believe that the Emperor is wearing clothes?
Paul in PA
Paul in PA, post: 350145, member: 236 wrote: "Baseline" is a well defined pairing of well controlled points.
John Nolton will likely jump in here soon to note that NGS uses the term "base line" (two words) to describe a monumented reference line. In any case, I use the words "baseline" and "vector" interchangeably. You're free to define one differently from the other, but I don't make that distinction.
Paul in PA, post: 350105, member: 236 wrote: A Baseline consists of at least two control points. One base and one rover is not and never will be a Baseline.
As to Javad's comments on short GPS vectors is all true. That is why on short lines L1 is as good as and sometimes better than L1/L2.
Paul in PA
Point taken. I was actually talking about what you would call a baseline in the earlier thread. Often the terms get a little mixed, and what people commonly refer to as a baseline in RTK work is their distance to the base unit or CORS.
Base Lines, Vectors , etc.
First I would like to say that Kent's post should of had the title of "Back to Basics". It has been known since the very first use of GPS that (1984 by Geo/Hydro) supplementing GPS vectors with EDMI measurements, angles etc. are very beneficial in the adjustment of your data. (ref. GPS Satellite Surveying, 3rdedition , by Prof. Alfred Leick , 2004, page 302, 8.1 GPS Vector Networks).
Second we have the spelling of base line: (I do like the way Mr. Jim Frame put it "You're free to define one differently from the other") Very diplomatically put. I sure don't want to perturb anyone, like anybody from Nebraska so just remember you can spell base line anyway you like...but its wrong if not spelled like base line or base-line, period.
To help the surveyor with base line spelling I have some references you can look up .
1. Manual of Surveying Instructions for the Survey of the Public Lands of the United States and Private Land Claims., January 1, 1902; look at the index
on page 193 and it says Base line. my comment; if this is the way the Manual that governs how to survey our land spells it, then it should be spelled that way.
2. Manual of Instruction for The Survey of the Public Lands of the United States, 1947, page 587 under index "Base line, method of survey,accuracy required".
3. Manual of Instructions for the Survey of the Public Lands of the United States, 1973, page 62, 3-10, BASE LINE
4. A Treatise On Surveying by William M. Gillespie, 1909 page 300, base line.
5. Webster's New Twentieth Century Dictionary of the English Language Unabridged, 2nd edition, 1975, page 154, "base line" is the entry word.
6. Boundary Control and Legal Principles, 2nd edition, by Curtis M. Brown, page 346 under Glossary of Deed Terms; BASE LINE is the entry word.
7. Geodetic Glossary, NGS, page 21, entry word; base line
8. Black's Law Dictionary, 5th Edition 1979 page 138, entry word "Base line"
So it is a GPS Vector and base line or base-line
You can spell it or call it anyway you want.
JOHN NOLTON
