Missouri Code of State Regulations
Title 2 - DEPARTMENT OF AGRICULTURE
Division 90 - Weights, Measures and Consumer Protection
Chapter 62 - First and Second Order Horizontal and Vertical Control
Section 2 CSR 90-62.050 - GPS Survey Guidelines

(1) Direct connections must be made to any adjacent observable National Spatial Reference System (NSRS) and/or Missouri Geographic Reference System (MO GRS) station located five kilometers (5 km) or less from any new station.

(2) At least three (3) existing higher or equal order control points must be included in any proposed Global Positioning System (GPS) survey. Whenever possible these should be three (3) three- (3-) dimensional control stations. Otherwise two (2) sets of three (3) stations, (three (3) two- (2-) dimensional horizontal stations and three (3) vertical control stations) must be used. These control stations should be chosen to be roughly equidistant on the periphery of the proposed project so that they enclose as much of the project as possible.

(3) Each new station to be established by the proposed GPS survey must be occupied at least two (2) separate times to enable proper checking of blunders (for example, incorrect point, setup errors, incorrect antenna heights). A separate occupation is one in which the antenna and its supporting device (tripod) have been taken down and set up again and the receiver restarted.

(4) Each station must be connected by simultaneous occupations (baselines) to at least three (3) other stations in the network after outlier baselines have been rejected from the adjustment. Because it is generally easier to resolve the integer phase ambiguities over shorter base line, adjacent stations should be connected wherever possible.

(5) At least two (2) receivers must be used for relative positioning, although three (3) or more may be used for more efficient opera- tion and increased station reoccupation and base line repeatability.

(6) A preanalysis should be performed to determine the minimum occupation time required to achieve the required standard of accuracy. In addition, the most appropriate satellites to observe at each site should also be selected for receivers unable to track all of the "visible" satellites. The preanalysis should be specific for carrier phase relative positioning.

(7) In order to meet second order accuracies, the carrier beat phase must be observedogether with a time tag for each observation. Pseudorange observations are not precise enough for control sur veys and cannot be used.

(8) A detailed field log must be kept during observation taken at each station. At the very least the following information must be recorded:

(9) The raw data files for all station occupations must be submitted. Each file will consist of one (1) set of raw observations for each station occupation session. For example, four (4) receivers operating during each of five (5) sessions will produce twenty (20) raw data files.

(10) The unadjusted baseline vector solution files for all observed baselines, non-trivial and trivial, will be submitted.

(11) If station description information is not provided by MDA, it must be submitted for each station occupied. Station descriptions must include station name, county, township, range, section, United States Geological Survey (USGS) 7.5-minute quadrangle name, date monumented, date of observations, complete descriptions of the station, azimuth and all reference monuments, a current "to reach" description, and any special information such as property owner name, address, and phone number. A sketch depicting the station and reference marks with dimensions and directions shown should accompany all narrative data. Examples of complete station description information may be obtained from MDA.

(12) If the GPS survey project includes any surveys using conventional or terrestrial hor- izontal surveying techniques, copies of all field notes and associated data must be sub- mitted. This would include eccentric point establishment and reduction. Polaris, solar, or direct observational data to establish azimuth marks shall also be submitted.

(13) When the GPS survey project includes surveys performed using conventional differ- ential leveling techniques, copies of all field notes and associated data must be submitted. An example of this would be a vertical tie from a nonoccupied bench mark to a GPS station.

(14) A tabulation of the results of the repeat base line comparisons will be included in the project report.

(15) A minimally constrained (free) least squares, three- (3-) dimensional adjustment will be submitted in the form of the input and output files.