[time-nuts] Crude Survey Technique

[Dale J. Robertson]

An interesting technique for improving the accuracy of single band gps is 
embodied in an open source program/project called rtklib.
Essentially it uses one GPS receiver in a fixed location that has been very 
carefully surveyed (gps reported location averaged over a long period) as a 
phase reference.
The roving receiver then uses the raw phase data from the base to subtract 
errors in the location of the rover.
10 cm accuracy is achievable in real time using consumer grade GPS 
receivers, though only a relative few provide the raw phase data required by 
the system. It is also possible to use one of the public internet feeds of 
gps phase data. The accuracy when using this approach depends on how close 
the reporting station is.
Of course in order to use this system in real time you need to establish 
connectivity between the base and rover. Simple WiFi should suffice for a 
couple hundred feet. 1200 baud packet would work for longer distances. A 
pair of u-blox lea-4t based gps receivers could be procured for under a 
hundred bucks.
I realize that this is gross overkill for the task at hand as there are 
tried and true (some might even pre-date christianity!) methods
available that would fit your needs.
Building this system is one of my 'time available' projects for the 
surveying of my property which covers 15 acres and has 16 corners.
Dale
NV8U

-----Original Message----- 
From: johncroos at aol.com
Sent: Thursday, November 21, 2013 1:52 PM
To: time-nuts at febo.com
Subject: [time-nuts] Crude Survey Technique

I wish to establish a north south line on my property to an accuracy of +/- 
2 degrees.
Could this be done by loading a T-bolt, Antenna, Power source, and laptop 
into my
little red wagon? The idea being to find two positions several hundred ft 
apart where either LH or T-bolt Mon report the same latitude? Will either of 
these programs report to sufficient accuracy? The base line would be 300 ft, 
though more is possible.I realizes that the T-bolt is not a survey device, 
but I can spend several hours fixing each position if required.

All comments appreciated.?? -73 john k6iql




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