Land Surveyor Forum

Replies

• GEO Ambassador

  Skip Farrow April 20, 2015 at 2:12pm

  here is also an article which may be of use to you..

  

   Distance PPM - The actual standard error used for the distance observation is made up of two parts, the constant and the proportional (distance times ppm). A value entered here represents the proportional distance measuring error of an EDM in parts per million. Say for example your EDM is rated as plus or minus 5 millimeters, and plus or minus 3 ppm, you would enter the value 0.005 meters (assuming your data is in meters) in the distance standard error field previously described, and the value 3 in the ppm field. Remember, if your project units are set to feet, you have to convert any millimeter rating to feet. In the example left, you would enter 0.016 feet for standard error, and the same 3 ppm.

   Angle Accuracy - The Angular Accuracy = 2 x (DIN 18723) / Square Root of the Number of Pointings. eg. 1 Sets (1fs+1bs) with a 1" second gun is:

  2 X (1") / square root 2=1.414"

  Another example: 3 sets (3fs+3bs) with a 5 second gun is:

  2 X (5") / square root 6= 4.082"

  Direction Accuracy - Is the DIN 18723 specification for Theodolite Accuracy applies to a repeated FACE 1 and FACE 2 pointings. (eg. A "1 second gun") 

  Horizontal and Vertical Centering - This is an estimate of the horizontal and vetical centering error, the inability to center over a mark. These values are used to inflate the standard errors of horizontal angles, directions, distances, and to some extent, observed zenith angles. As a rough guide, for instrument centering error we find values around 0.005 feet (0.0015 meters) commonly used for optical plumbs, and 0.010 feet (0.003 meters) or more for string plumbs. Target centering depends on the kind of target and care used in setting up. What values you use for centering error must be based on equipment, field conditions, your crew and experience.

  Learn more about the DIN 18723 specs from the link below:

  ftp://ftp.cefetes.br/cursos/Geomatica/Geraldo/Visual%20Basic/Din187...
  • Land Surveyor

    RAYMOND KINGSLY > Skip Farrow April 21, 2015 at 1:51pm

    Thank you for your valuable reply sir,

                           here i am submitted my details of fs distance,bs distance,instrument setting ,

    the included angle of bs and fs  ,sir i want to know how much standard error in angle and distance

    my station setting details

    at AT ST1, BS ST6 ,FS2

    INCLUDED ANGLE=110DEGREE 38 MINUTE 58 SECOND

    ST1 TO ST6 BACK SITE DISTANCE=308.720m

    ST1 TO ST2 FORE SITE DISTANCE=226.352m

    INSTRUMENT SETTINGS

    DISTANCE CONSTANT=0.001m

    DISTANCE PPM=1.5

    ANGLE=4

    DIRECTION=3

    AZIMUTH/BEARING=4

    CENTERING ERROR:

    HORIZONTAL INSTRUMENT=0.002m

    HORIZONTAL TARGET=0.002m

    Sir my question is what is the standard error in angle.

    STARNET CALCULATED ANGLE STANDARD ERROR OF 5.29

                                         BUT I WANT TO CONFORM IT BY MANUEL CALCULATION THANK U SIR.
• GEO Ambassador

  Skip Farrow April 20, 2015 at 2:11pm

  Attached is the Manual for STARNET v6 which may be of help to you..