CHLPRAN             Enter the desired azimuth and distance specifications.                                                                  The azimuths may be entered in any order. When you are      finished, exit by pressing function key <F10>. The radials  will be sorted in order of the azimuth values. After the    sort any duplicate azimuth values will be deleted.                                                                      To add an additional radial press <F2>. A new radial will beadded after the current cursor position.                                                                                To delete a radial, position the cursor on the radial to be deleted and press <F8>.                                                                                                 Note that you cannot delete ALL of the radials.  If you wantto change the method of specifying the data to be extracted you can exit from this radial selection window. Even if     radials are still shown in the window, these will be        replaced by either of the other methods (sequential azimuthsor target coordinates).                                                                                                
CHLPCOR             Enter the latitude and longitude of the desired target site.The azimuth and distance to each site will be computed.                                                                 The site coordinates may be entered in any order. When you  are finished, exit by pressing function key <F2> or the     <TAB> key. The radials will be sorted in order of the       azimuth values. After the sort any duplicate azimuth values will be deleted.                                                                                                        To add an additional radial press <F2>. A new radial will beadded after the current cursor position.                                                                                To delete a radial, position the cursor on the radial to be deleted and press <F8>.                                                                                                 Note that you cannot delete ALL of the radials.  If you wantto change the method of specifying the data to be extracted you can exit from this radial selection window. Even if     radials are still shown in the window, these will be        replaced by either of the other methods (sequential azimuthsor selected azimuths).                                                                                                  
CHELPN1             You have two choices for specifying and/or printing distanceand elevation values:                                                                                                     (B)ritish units: feet and miles                                                                                         (M)etric units:  meters and kilometers                                                                                                                                            
CHELPN2             This program  permits two  methods of specifying the path to be studied.                                                                                                            You may either:                                                                                                          * Enter the azimuth and distance from the primary site,                                                                   OR                                                                                                                    * Enter  the coordinates  of a target point at the end of     the path                                                                                                             
CHELPN2A            This program accepts radial azimuth(s) and start/stop/step  distances for extraction of terrain data.  You may specify  either:                                                                                                                   * Sequential radials (e.g., 0, 45, 90, etc.)                                                                              OR                                                                                                                    * Selected (random) radials (e.g., 35.7, 241.0, etc.)                                                                 
CHELPN2B            Select the range of sequential radial azimuths. You must    specify the starting and stopping azimuths, and the         increment (or step) value.                                                                                              The azimuths must be between 0 and 360, inclusive.  If you  want a sequence that starts below 360 degrees and continues through and past 360 you must retrieve the data in two      passes. For example, suppose you want only azimuths from 270to 90 degrees in 10 degree steps. You must first extract thedata from 0 to 90, and then from 270 to 350.                                                                            
CHELPN2C            For the radial azimuth(s) selected, enter the distances fromthe primary site to start and stop the elevation data, and  the distance increment between the data points.                                                                         The starting distance must be greater than zero. If you wantto start from the primary site, specify a value such as .1  miles or kilometers.                                              
CHELPN3             Select the data base to use for this session. Either the    30-second or the 3-second data base can be used.                                                                        
CHELPN4             This program provides three options for interpolating the   data from the data base:                                                                                                      * The prescribed FCC method using four points from thedata base, OR                                                                                                                 * A weighted method  using twelve data points from thedata base                                                                                                                     * A non-interpolation "maximum elevation" method.                                                                 The  FCC   method  is  satisfactory  for  computing  terrainAVERAGES, but  tends to  "flatten" the actual values:  peaksappear too low, valleys appear too high.                                                                                The  weighted   method   includes   consideration   of   thesurrounding slope  to improve the accuracy of the individualdata points  extracted from  the data  base,  but  increasesexecution time,  since twelve  data  base  points  are  usedinstead of four.                                                                                                        The maximum elevation method selects the highest of the four"corner" data base grid points around each target point. No interpolation is performed. This method approximates a      "worst case" terrain obstruction for the path(s) being      extracted.                                                                                                              
CHELPN5             If you  are writing  the elevation averages, the result willbe one line for  each radial.  A typical session of eight ornine radials  will  fit  conveniently    on  a  single  pageexhibit.  Seventy-two radials will require three pages.                                                                 You may also elect to write additional information regardingthe elevation  data pertaining to the radial(s) under study:                                                                 You may  write the  elevation  of  EACH  POINT  on  the     radial.   (You  may  also  later  elect  to  write  the     elevation of  each point in an ASCII file.  The present     selections involve only the output to be printed.)                                                                      If you  print the elevation of each point on the radial     you may  also write  the elevation  of each of the four     NGDC data  file points  which form the "corners around      the point  on the  radial which are used to interpolate     the radial point elevation.                                                                                        Each of  the options  will substantially increase the volumeof the  output of the program.  Eight radials may require 75pages if  every point  and the   corresponding  corners  areprinted.                                                                                                                    
CHELPN6             Enter the file name extent to be used to save the elevation data. If an existing file is used, new radial data will be  added to that file. If a new file extent is used, a new filewill be created.                                                                                                        Press <F9> to see a list of existing elevation files for    this JOB number.                                                                                                        Note that adding elevation data to an existing file can     significantly increase the program execution time if the newradial azimuth values are below the values already in the   file.  Radial data is stored sequentially for more efficientuse of the data files by other TAP programs. If lower       azimuth values are added, all existing data in the file mustbe rewritten to make room for the new data.  Try to write   radials in ascending order, or specify a new extent to      create a new file.                                                                                                      
CHELPDSKCHG         This program will look for the required elevation data base files according to the paths specified in the system        configuation screen. These paths (primary and alternate) arenormally specified as the hard disk or CD-ROM drive.                                                                    If the required file is not found in either of these paths, the program can prompt you to insert the required floppy    disk or CD-ROM disk.                                                                                                    However, you also have the option of suppressing this promptasking for another disk.  For example, if you want to       extract a large amount of data without interruption, answer "N" to this prompt. During the data extraction for each     radial, if a data file is not found, no prompt will will be issued for a disk.  Some of the required points on the      radial will not be included in the resulting file.                                                                      Note that the data file for the site location MUST be       available. If this file is not found and the change disk    prompt is suppressed, the program will abort.                                                                           
RADIAL INPUT        This program permits two methods of specifying the path to  be studied.                                                                                                             You may either:                                                                                                          þ Enter the azimuth and distance from the primary site, and   the coordinates of the end of the radial will be computed                                                               OR                                                                                                                    þ Enter  the coordinates  of a target point at the end of     the path and the azimuth and end ("stop") distance will     be computed.  You can save target coordinates to a file     that can be retrieved later, for example to use the same    coordinates to compute radial azimuths and distance from    a different site.                                                                                                    In either case you must enter a starting distance from the  site and a distance step value which will be used to        increment the distance for the points along the radial.                                                                 You can also specify a sequence of azimuths to generate     evenly spaced radials with the same start, stop, and step   distances.                                                                                                              
CHELPDATABASE       This program currently supports three point-elevation data  bases:                                                                                                                    þ 30-meter data                                             þ 3-second data                                             þ 30-second data                                                                                                      The files are searched for each data point in order of      decreasing resolution (as shown on the above list) for each data base you select (by answering "YES").                                                                              You can also specify the disk change option for each data   base independently.  For example, if all of your 30-meter   data files are on your hard disk in your data path, you can answer "NO" to the disk change option for that data base,   but "YES" for 3-second data, so if a data file is needed    that you do not have in 30-meter data, you will not be askedfor the 30-meter file.  The program will look for the file  in the 3-second data and prompt you for the needed CD-ROM ifthe file is not found.                                                                                                  
