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| Figure 1. NGS Home Page |
|
|
The Internet address for the NGS is
www.ngs.noaa.gov.
Once the home page loads, click on Products and Services, a link in a list of links along
the left side of the page under the header Site Contents. Scroll down the Products and
Services page and click on the link for Geodetic PC Software Programs under a bold
Software header. This will take you to a page with another Geodetic PC Software Programs
link; click on it as well. Scroll down the next page and click on the SPCS83 (Version 2.0)
link.
This will bring you to a page headlined Current directory is
/pub/pcsoft/spcs83. Scroll down through the warnings until you find these three files:
spcs83.doc, spcs83.exe and spcs83.for. Download these files by clicking on them.
|
Station
Name |
Latitude
(North) |
Longitude
(West) |
|
| Bromilow |
32 16 52.33969 |
106 45 15.77636 |
| Reilly |
32 16 55.93458 |
106 45 15.16429 |
| Wakeman |
32 17 00.10142 |
106 45 29.49809 |
 |
| Figure 2. Sketch of Sample Problem |
|
|
Figure 2 is a sketch of the sample problem. There are three
stations, all established using GPS. NAD 83 geodetic coordinates for each station are
given in the figure. We will use SPCS83 to calculate the state plane coordinates for each
station.
With SPCS83 ready on your computer, do the following:
SPCS83 is a DOS program; the executable file is SPCS83.EXE. Type spcs83
and hit the enter button.
You will see the following:
*** PROGRAM SPCS83 *****
VERSION NUMBER 2
LAST UPDATE 06/27/88
DO YOU WANT TO COMPUTE:
GEODETIC POSITIONS TO STATE PLANE COORDINATES STATE PLANE COORDINATES TO GEODETIC
POSITIONS PRINT THE OUTPUT FILE ON THE PRINTER TYPE NUMBER
Type 1, hit the enter button.
The following line will appear:
DO YOU WANT TO RUN INTERACTIVELY (Y/N)?
Type Y, hit the enter button.
The following line will appear:
DO YOU WANT THE OUTPUT SAVED IN A FILE (Y/N)?
Type Y, hit the enter button.
Give a name to the output file. It should be no more than eight
characters. Then hit the enter button.
Follow the instructions on the screen for entering latitude and
longitude. When asked for direction of longitude, enter W, for west longitude.
The last question asked is
ENTER ZONE CODES, AS MANY AS THREE
STATION
NAME |
LATITUDE
(NORTH) |
LONGITUDE
(WEST) |
NORTHING
(Y) METER |
EASTING
(X) METER |
ZONE |
CONVERGENCE |
SCALE
FACTOR |
ELEV
(M) |
GEOID
HT (M) |
| D |
M |
S |
| Bromilow |
32 16 52.33969 |
106 45 15.77636 |
142158.262 |
452489.852 |
NM C |
-0 |
16 |
9.78 |
0.99992783 |
1 |
1 |
| Reilly |
32 16 55.93458 |
106 45 15.16429 |
142268.912 |
452506.387 |
NM C |
-0 |
16 |
9.48 |
0.99992781 |
1 |
1 |
| Wakeman |
32 17 0.10142 |
106 45 29.49809 |
142399.023 |
452131.948 |
NM C |
-0 |
16 |
17.17 |
0.99992825 |
1 |
1 |
 |
| Figure 3. State Plane Zones |
|
|
Figure 3 shows zone codes for each zone of every state. In our example,
the zone is New Mexico Central, zone 3002. (We only have one zone in our sample problem.)
Repeat this procedure for every station. At the end, print the output
file. For our sample problem, the output file is shown in Figure 4.
We are now ready to traverse on the state plane grid. Looking at Figure 4,
we input the latitude and longitude, on the 1983 datum, for stations Bromilow, Reilly and
Wakeman. The output for each station are the northing, easting, convergence and scale
factor. (We haven’t discussed convergence, that will be in the next, and last column,
of this series.) This is what we are looking for: Inversing between each pair of
coordinates gives the grid distances. Taking the coordinate differences leads to the grid
azimuth. From the differences in grid azimuths we get horizontal angles. We will do all
these calculations, and more, in the next column.
