MEMORANDUM FOR: All Users, Program PCVOBS FROM: Janice M. Bengston Vertical Network Branch National Geodetic Survey SUBJECT: PCVOBS Revision, Version 2.00 Several requests for specific enhancements to PCVOBS have been made by State Geodetic Advisors Dennis Wegenast, Washington, and Lyle Riggers, Oregon. As a result, PCVOBS has been altered to facilitate keyboard entry of data for multiple parts of a leveling project. GPS surveys often require many small leveling ties with only a few bench marks on each line. Each of these ties is a complete leveling line, and as such, is assigned a separate part number for the same project number, and has beginning and ending job code records on the input file. In previous versions of PCVOBS, the user had to exit the program each time an ending job code record was written to a leveling line. For each additional part number, the user was required to start a new execution of PCVOBS and reenter data, much of which was common to all parts. PCVOBS, Version 2.00, permits the user to input multiple parts of one project into a single file. Although there is no limit to the number of parts which may be entered, the file, in its final form, must end with the completion of a line/part, i.e., an ending job code record. (The user has the option of completing a line, or part of a line, at another session, but the last record of the final file must be an ending job code record.) An observation (HGZ) file with multiple parts must have a single description file (HA), containing new or recovery descriptions for every bench mark. If both leveling and GPS surveys are performed for a project, only one description file is required. Each mark should be assigned only one SPSN within the project, and each SPSN must be unique throughout the project. Thirty- Records (*30*) must be input for each part, in line order. The SPSN's of the observation (HGZ) file must correspond exactly with the SPSN's of the description (HA) file. When PCVOBS, Version 2.00, is executed, the information for the job code , *10* and *11* records, and rod and instrument data for the *40* records are stored. Subsequent parts print the appropriate information when needed and the user may optionally change certain data specific to the part being entered. A *12* (subtitle or line title) record must be entered for each part. After all *40*, *41*, *42*, and *43* records have been entered, the user responds "n" (no) to the program request for another *40* record. Then, the program will ask if this is the end of the line/project? If the response is "n", the program will exit and an ending job code will be not be written to the file. The user must complete the file by executing PCVOBS at a later time. If the response is "y" (yes), an ending job code will be written and the user is asked if another line/part is desired. If another part is to be done, PCVOBS prints the information from the beginning records of the previous part, prompts for optional changes, writes a beginning job code record, and continues the prompts for the rest of the new part. These new enhancements to PCVOBS will remedy the problem of repeatedly entering data common to many line parts. If you have any questions, suggestions, or you find any errors, please contact: Janice Bengston Vertical Network Branch N/CG133, Rockwall Bldg., Room 405 National Geodetic Survey, NOAA Rockville, MD 20852 Telephone: (301) 443-8440 Basic Definitions Chapters - Page Numbers (In Parentheses) Refer to: "Input Formats and Specifications of the National Geodetic Survey Data Base" "Volume II. Vertical Control Data" Job: Basic unit or grouping of data to be submitted. It may consist of a single project or a number of projects. Identified by a two-letter job code on *AA* record. (5-2). Project: One unit of field work consisting of one or more leveling lines. (5-2) Leveling line: A unit of field work consisting of a number of survey points (bms and tbms) connected by chains of differential leveling (runnings). Each leveling line is assigned an HGZ identification which begins with "L" (or "GPS" for GPS) followed by up to 5 digits. If the leveling line is one of several parts of a project, a part number is indicated. (5-2 to 5-3) Section: A segment of a leveling line consisting of two neighboring survey points connected by a running (*41* record). SPSN: (Survey Point Serial Number) Each survey point that is leveled to in a vertical control job must be assigned a unique four-digit serial number in the range 0001 through 9999. The SPSN assigned for a mark listed in the *30* record must be used to refer to the same mark on the *41* records and also, on the HA (bench mark description) records. (5-4) Records Each record is 80 characters long. The type of information a record will contain is specified by the code. *AA* Required - Job code record (Enter "AA" if not known) (User is prompted for the code only, not "*") *10* Required - HGZ identifier ("L" - leveling, "G" - GPS), Tolerance *11* Required - Project/Line Title *12* Required if no *11* record - Continuation Line Title *13*...*15* Optional comment records *20*,*21* Not included in PCVOBS - Rod, instrument information; only needed the first time a rod or instrument is used. Not needed for third order or lower lines; first or second order lines need calibration. Information can be sent to NGS. *30* Field abstract - Bench mark designation SPSN (unique for project) Running totals - (optional, but desirable) distance, cumulative height difference All *30* records are entered in line order, as a group before observation data. Additional *30* records cannot be entered after any observation data (*40*, *41*) has been entered. *40* Required - One *40* record for each leveling day; Rod, instrument information, collimation error If instrument or rods are changed during the day, a new *40* record must be entered. *41*,*42* Required - One *41* (or *42*, river crossing) record for each (*43* leveling observation performed on the day recorded in the generated) preceding *40* record. Running data - (minimum requirements) from SPSN to SPSN section distance height difference *AA* - generated at the end of the project Note: All data for a particular project/line does not have to be entered in a single PCVOBS session. However, additional *30* records for a single line/part cannot be entered after a *40* record has been entered. Multiple line parts of a project may be entered on one file. A single line/part may not be continued after the ending job code has been recorded. If this situation occurs, start a new file for the remainder of the line and combine the two files later, or notify NGS to concatenate the two files. PCVOBS Preliminary Considerations 1. If you anticipate sending data to NGS before the survey work is started, call Emery Balazs, Chief of Geodetic Leveling Section (phone 301-443-8567). He will assign a job code, line (HGZ) number, and a title, which will be recorded by NGS. 2. Identify the complete line, i.e. all marks to be leveled. Determine the connectivity of the marks. (It is very difficult to go back after the line is completed.) Before Running PCVOBS 1. Assign arbitrary unique four-digit numbers to each mark leveled (SPSN). Usually, number sequentially beginning with 0001. 2. If the project includes several interconnecting lines, assign only one value to each mark. Thus, SPSN 0001 will refer to the same mark in each leveling line of the job. 3. Make a list of marks and their SPSN's in the order of the designated leveling route.