Hacker Chronicles 2

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C O N G R A T U L A T I O N S You now have the easiest to use, least expensive, satellite tracking package available in shareware. The capabilities provided by PC-TRACK were previously limited to programs which were hard to use, expensive, and designed for mini-computers or more expensive 80286 and 80386 based personal computers. Now you can graphically track your favorite terrestrial satellites with ease, accuracy, and money left in your pocket. ABOUT THIS MANUAL PC-TRACK was written to be simple enough to use without any documentation. PC-TRACK incorporates context sensitive on-line help to assist with any area of question. In an effort to make PC-TRACK as useful as possible, this manual is also provided for your assistance. It will provide you with detailed explanations of the way PC-TRACK works and its features. It will also will provide you with helpful tips and information which will help you get the most from PC-TRACK. COPYRIGHT STUFF PC-TRACK is marketed as SHAREWARE. IT IS NOT PUBLIC DOMAIN SOFTWARE! This means that anyone can make copies of PC-TRACK to distribute to others for the purpose of evaluating the package for usefulness. But if you decide that PC-TRACK will be useful to you and decide to use it regularly, you must register your copy. This means paying for the use of the software. See the file called README on the disk or the messages in PC-TRACK for details on how to register. All rights to PC-TRACK are held by Thomas C. Johnson. PC-TRACK is Copyright (C) 1989 by Thomas C. Johnson. PART I INTRODUCTION AND INSTALLATION GENERAL DESCRIPTION PC-TRACK is a general purpose satellite tracking package designed to take the complexity and confusion out of finding where an earth orbiting satellite is in space and providing the antenna pointing data necessary to transmit signals to or receive signals from them. HISTORY PC-TRACK has its origin in a satellite tracking program I wrote to track the OSCAR (Orbiting Satellite Carrying Amateur Radio) series of amateur radio satellites back in 1980. That program was called OSCAR PATHFINDER and was the front cover feature article in the March 1982 edition of "73 Magazine For Radio Amateurs." That program was written for the Apple II plus computer in Applesoft BASIC. It was a revolutionary program at that time in that it was the only program that tracked satellites in real time (the Apple had no clock) and displayed the satellite path on a map on the graphics screen. It was capable of only tracking circular orbiting satellites, but that was not a problem at that time because all of the amateur radio satellites were in circular orbits. OSCAR PATHFINDER was so enthusiastically received that I made the decision to make some improvements to the program and offer it commercially. This led to a venture called Computer Applications and I sold quite a number of copies of Pathfinder II. I then developed a version of the program for the TRS-80 Model III computer called Pathfinder III. After a year or so of selling these packages, myself and my partner decided (for various reasons) to pull the plug on this and go on to other things. Later, with the launch of several elliptical orbit amateur satellites, I tinkered with the program some more to include the math necessary to track such satellites. This resulted in Pathfinder X, which was never published, but I used it quite a bit at home for my own tracking needs. I had also started rewriting the program in UCSD Pascal because that offered a much more readable and manageable structure for the program. When I got my IBM PC/XT clone in 1985, I had a desire to port Pathfinder X over to my new "supercomputer" since it had an 8Mhz clock and would be able to do faster computations and have better graphics capabilities. Well, after many years of many distractions (other business ventures, kids being born, moving, etc.) I have finally put together my idea of a nifty package for tracking satellites, called PC-TRACK. FEATURES PC-TRACK provides the capability of managing two data bases. One for the objects to be tracked, and another for the observation points. PC-TRACK has the capacity for handling 100 objects and 100 observation points. These can be easily entered and updated using built in modules. PC-TRACK can track an object in real time or make predictions of satellite position both forward and backward in time. Tracking can be paused at any time for display analysis. PC-TRACK can send the computed data to your printer at any time, either printing all points computed or only those within range of the selected observation point. PC-TRACK prints a header containing the object tracked, observation point name and data, and column headers at the top of each page to provide a neat, identifiable document. PC-TRACK uses the standard EGA screen so you can use any of the many screen dump or screen capture programs available to print or save displays. PC-TRACK also has a configuration module which enables you to configure the colors of the text screen to your liking and to setup the printer control commands to be used by your printer for printouts. It also enables you to define the disk and subdirectory where PC-TRACK will find the data files it needs. Finally, PC-TRACK has an on-line help system called PC-TRACK ASSISTANT built in which is context sensitive. It provides help for whatever piece of information you are entering or feature you are accessing. Once in the help system, you may also browse through the rest of the help screens to get information on whatever topic you desire. SYSTEM REQUIREMENTS SYSTEM: IBM PC/XT/AT or compatible. DISPLAY: EGA (640X350 16 Color) MEMORY: 512K DISKS: 1 Floppy Disk (hard disk is better) PRINTER: Any capable of printing at 5, 10, and 12 CPI, and 12 LPI (any other will work but printouts could run off page) INSTALLATION PC-TRACK is distributed on one 360K floppy. PC-TRACK includes all the files and data needed to run. (Data should be updated as soon as possible to insure predictions are accurate. Satellite data gets old after a couple weeks. Besides that, PC-TRACK will most likely not have the location data for your observation point.) It is wise for you to immediately make a backup copy of everything on the distribution disk to another disk. I recommend doing this by using the DISKCOPY command. Put the original away as a master. If you are using a hard disk. Make a subdirectory on it and copy all the operational files to it. (Don't forget to change directories to the one you just created before you begin copying.) You will not want to take up room on your hard disk with the documentation and support files. If you are using floppy drives, format a floppy disk with the operating system on it and copy all the operational files to the new disk. You may then put an AUTOEXEC.BAT file on it to have it automatically begin running when you boot up. (Somewhere in the AUTOEXEC file have a line with "PCT" on it.) ------- F I L E S P R O V I D E D ------- FILENAME DESCRIPTION ---------------------------------------------------------------- OPERATIONAL FILES PCT.EXE PC-TRACK Satellite Tracking Program WORLD.MAP Binary data for the world map used in the tracking screen in PC-TRACK. PCT.HLP Text file containing the PC-TRACK help messages for the on line help. PCTCOLOR.DEF Contains the system colors used for the text screens in PC-TRACK. PCTSYS.DEF Contains the system configuration parameters and the printer control codes. OBJECTS.DAT Data file containing satellite orbital elements for each satellite in the data base. OBSERVER.DAT Data file containing the location data for each observation point in the data base. DOCUMENTATION AND SUPPORT FILES PCT.DOC This Users Manual README Gives introductory information concerning PC- TRACK. -------------------------------------------------------------- PART II O P E R A T I O N GETTING STARTED PC-TRACK is started from the DOS prompt by entering PCT <RETURN>. PC-TRACK begins by presenting you with a pretty colored hello screen. There will be a brief pause at this point while PC-TRACK loads in the help screens and the world map. This takes a few seconds (depending on the computer used). You will see a message at the bottom of the hello screen which says "INITIALIZING... PLEASE WAIT." Once initializing is completed, you are presented with the main menu screen. This is a small shadowed window on the left side of the screen with the 4 main module options listed. The four module options are SETUP, TRACK, CONFIGURE, and QUIT. Selecting one of these options is done simply by moving the cursor (shown by selected name being in a different color than the rest of the options listed) so that it highlights the module desired and pressing the RETURN key. USING THE ON-LINE HELP The on-line help system is available from anywhere in the program and can be accessed simply by pressing the F1 key. The information presented on the help screen will be dependant on where you are in the program. For example, if you are in the SETUP OBJECTS option with the cursor on the NAME field and you press the F1 key, the help screen will pop up and give you specific information on entering the NAME field data. Once you are in the help system, you may browse through the information provided by pressing the Page Up, Page Down, Up Arrow, or Down Arrow. Page Up does the same thing as the Up Arrow key and Page Down does the same thing as the Down Arrow key. You may get back to the original screen by pressing the HOME key. When going "down" in the system, you will be able to step through every screen in the help system. When going "up", you will skip up to the top screen of the previous major topic in the system. This allows you to move quickly through the screens to the one you wish to see. >>> S E T U P <<< The SETUP module is the built-in data manager for the satellites and observation points to be used in PC-TRACK. With it you can enter and edit, and delete all information necessary to do satellite tracking with PC-TRACK quite easily. To select the SETUP module, move the cursor using the arrow keys to SETUP. Then press the RETURN key. A second menu window will appear with the options OBSERVERS and OBJECTS. The OBSERVERS option handles data for the observation points and OBJECTS handles the data for the satellites. Select the desired option by again moving the cursor to highlight the one you want. There are various keys that will assist you in the entry and editing of observer or object data while in the SETUP module. They are as follows: F2 - ADD OBSERVER/OBJECT This key allows you to create a new entry in the observer/object file where information about a new observer/object can be put. When this key is pressed, all the screen fields are cleared so you can begin entering new information. F3 - REMOVE OBSERVER/OBJECT/OBJECT This key does just the opposite of the F2 key. It PERMANENTLY removes the currently visible observer/object from the file. Since this action is PERMANENT and IRREVOCABLE, a warning window pops up to alert you to the fact that this will occur if you continue. If you press RETURN in response to the warning window prompt, you will remove that observer/object from the file. If you press ESC or any other key, you will not remove the observer/object and you will go back to where you were when you pressed the F3 key. PAGE UP - PREVIOUS OBSERVER/OBJECT/OBJECT This key will display the previous observer/object in the file. Observer/objects are stored in the file in the order they are entered. Once the observer/object you desire is visible on the screen, you may edit any of the fields. If you step past the first observer/object in the file, the last will be displayed. PAGE DOWN - NEXT OBSERVER/OBJECT/OBJECT This key will display the next observer/object in the file. If you go past the last observer/object in the file, the first will be displayed. SETUP OBSERVERS The OBSERVERS option opens up the data entry window on the right hand side of the screen. This window shows the six fields (pieces of information) held for each observation point you have in the file. The six pieces of information necessary to describe an observation point are as follows: DESCRIPTION: This field is your way of easily identifying each of the observation points you have in your file. This is a text field with room for up to 30 characters (anything you want). For example, you can put the names of the nearest associated city with the state, such as Dayton, Ohio. Or if you have a lot of observation points entered, you might devise some numbering system to systematic identify each location. This could be something like OH-39N-84W, which would be a location in the state of Ohio, near 39 north latitude and 84 west longitude. I'm sure you can devise some more sensible system because as you see below the latitude and longitude are already included with the description. LATITUDE: This along with longitude defines the location on earth of the observation point. Latitude is entered as degrees and decimal fractions of degrees. Latitude will be entered as a positive number if it is in the northern hemisphere and negative (-) for those in the southern hemisphere. For example a position with a northern hemisphere latitude of 34 degrees, 30 minutes, and 15 seconds would be entered as 34.5694444. That same latitude in the southern hemisphere would be entered as -34.5694444. This may be entered as a number between -90.0 to 90.0. LONGITUDE: This along with latitude defines the location on earth of the observation point. Longitude is entered like latitude as degrees and decimal fractions of degrees. Longitude is entered as positive values for the western hemisphere (North and South America, Greenland, etc.) and negative for the eastern hemisphere (Europe, Asia, Russia, etc). This may be entered as a number between -180.0 and 180.0. MINIMUM ELEVATION: This figure describes the lowest elevation a satellite may be visible from the observation point. An observation point with a perfectly clear horizon around it would have a minimum elevation of 0.0 degrees. If there are mountains or buildings around it the minimum elevation would be higher. This may be entered as a number between 0.0 and 90.0. This number is used as a filter for displaying and printing azimuth/elevation data. Only satellite view angles with elevations above the minimum will be displayed or printed. TIME ZONE: This describes the number of hours from UTC time (Coordinated Universal Time) (used to be called GMT or Greenwich Mean Time) your local time zone is. Time zones in the western hemisphere are positive while eastern hemisphere zones are entered as negative. For example, Eastern Standard Time would be entered as 5 hours from UTC time. Pacific Standard Time would be 8 hours. If you wish your displays and printouts to be in UTC time, enter 0 and make sure the DOS clock is set to UTC time. Time Zone may be entered as whole numbers between -12 and 12. HEIGHT: This describes the height in feet your observation point is above Mean Sea Level (MSL). If you are not sure what the height is for the observation point, enter 0.0. Height may be entered as any value between -400.00 and 30,000 feet. SETUP OBJECTS The OBJECTS option also opens up the data entry window on the right hand side of the screen. This window shows the twelve fields (pieces of information) held for each object you have in the file. This information is available from a number of sources. See appendix A for the cheapest and most reliable source for this information. The twelve pieces of information necessary to describe an object are as follows: NAME: This is a 20 character field which you can use to name the object for easy identification. CATALOG (OBJECT) NUMBER: This is a 5 digit number assigned to each object. It is used as the reference number in the NASA source identified in Appendix A. EPOCH YEAR: This is the year of the specific time the rest of the data about the object is effective. When entering Epoch year, make sure you include all 4 digits of the year, ie. 1989. Some data sets such as those from Nasa include only the last 2 digits of the year. PC-Track requires all 4. EPOCH DAY: This is the day and fraction of day for the specific time the data is effective. This number defines both the julian day (the whole number part of the value) and the time of day (fractional part of the value) of the data set. The julian day figure is simply the count of the number of days that particular date is from the beginning of the year. (January 1 would have a julian day of 1. Feb 28 would be 59.) This number may range from 1.0 to 366.999999999 (taking into account leap years). DECAY RATE: This is the rate of decay of the orbital period (time it takes to complete one revolution) due to atmospheric friction and other factors. It is a real number measured in terms of Revolutions per Day per Day (REV/DAY/DAY). INCLINATION: This number describes the angle of the plane of the orbit in relationship to the earths equator. Inclination is 0 degrees for a object orbiting directly over the earths equator and orbiting in the same direction as the earth's rotation. It is 180 degrees for an object revolving directly over the equator counter to earth's rotation. An object orbiting directly over the poles would have an inclination of 90 degrees. Inclination is given as a real number of degrees between 0.0 and 180.0 degrees. RIGHT ASCENSION OF ASCENDING NODE: This value describes the point the satellites crosses the equator from the southern hemisphere to the northern hemisphere (ascending node). This measured eastward along the equator from the vernal equinox (right ascension). It is given and entered as a real number of degrees from 0.0 to 360.0 degrees. ECCENTRICITY: This is a unitless number which describes the shape of the orbit in terms of how close to a perfect circle it is. This number is given in the range of 0.0 to less than 1.0. An perfectly circular orbit would have an eccentricity of 0.0. A number greater than 0.0 would represent an elliptical orbit with an increasingly flattened shape as the value approaches 1.0. ARGUMENT OF PERIGEE: This value is the number of degrees from the ascending node the perigee point occurs. The perigee point is the point where the satellite is the closest to the earth (assuming an orbit which is elliptical to some degree). This number may be entered as a real value between 0.0 and 360.0. MEAN ANOMALY This number represents the angular distance from the perigee point (closest point) to the satellite's mean position. This is measured in degrees along the orbital plane in the direction of motion. This number is entered like the argument of perigee, as a value between 0.0 and 360.0. MEAN MOTION: This is the number of complete revolutions the satellite makes in one day. This number may be entered as a value greater than 0.0 and less than 20.0. When all of the pieces of information have been input for an object and you have no other objects to enter, press ESC to get back to the main menu. REVOLUTION NUMBER This represents the number of revolutions the satellite has completed at the epoch time and date. This number is entered as an integer value between 1 and 99999. >>> TRACK <<< The TRACK module is the heart of PC-TRACK. It is where the graphical presentation of the satellite position is done. Moving the cursor to this option brings up a selection screen before going on to the track screen. SELECT This screen allows you to easily select an object and an observer from those you have entered into the files using the SETUP option. Your selections are made by simply using either the Up or Down Key. Once the object or observation point is visible press RETURN. After selecting which object to track and the observation point, you will be asked to define what data is to be printed (if enabled) during track. You have a choice of either printing every point computed or only those which have satellite elevations from the observation point greater than the minimum elevation entered for that point. Once the desired answer is provided by using the Up or Down keys and pressing RETURN, tracking begins. TRACK SCREEN During the tracking process information is provided within a number of separate boxes on the screen. The general locations of these boxes on the track screen and the information presented are described below. ┌────────────────────────────────────────────────────────────┐ │ T I T L E B O X │ └────────────────────────────────────────────────────────────┘ ┌─────────────┐┌────────────────────────────┐┌───────────────┐ │ STATUS BOX ││ DATE/TIME BOX ││ TIME INTERVAL │ └─────────────┘└────────────────────────────┘└───────────────┘ ┌───────────────────────────────────────┐┌───────────────────┐ │ ││ │ │ ││ │ │ O B J E C T B O X ││ S T A T I O N │ │ ││ │ │ ││ B O X │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ │ ││ │ └───────────────────────────────────────┘│ │ ┌───────────────────────────────────────┐│ │ │ H E L P B O X ││ │ └───────────────────────────────────────┘└───────────────────┘ TITLE BOX This shows the title of the program and the name of its author. This is presented across the top of the screen. STATUS BOX This box shows the status of the various modes available for selection during the selection process. The messages which will show up in this box are as follows... Real Time Track - Indicates PC-TRACK is tracking the satellite in real time. Fast Track - Indicates PC-TRACK is computing and displaying satellite positions as fast as possible ignoring the internal clock. Pausing - Indicates PC-TRACK has temporarily halted the tracking process and is waiting for the F3 key to be pressed again to resume tracking. Printing - Indicates PC-TRACK is enabled to send tracking data to the printer. The amount of data sent to the printer is determined by the type of data selected during the SELECT process just before tracking began. DATE TIME BOX PC-TRACK is a time based tracking package, which means that it first generates a time and date and then figures out where the satellite is at that time and date. Therefore, the central display is the time and date of the current satellite position. This box is just below the title box in the upper center of the screen. TIME INTERVAL BOX The time interval box displays the current time interval used in picking each time used to compute the satellites position. The interval is added to the current track time (shown in the DATE TIME BOX) to generate the next time to compute the satellite position. This interval is initially set to 1 second. It may be modified by various function key combinations as described below when in the Fast Track Mode. Interval is fixed at 1 second in Real Time Mode. For example if the current time shown in the DATE TIME BOX is 09:03:32, and the interval is 00:00:05 (5 seconds) then the next time that will be used to compute the satellite position is 09:03:37. The time Interval remains wher you set as long as PC-Track is running. OBJECT BOX The object box shows all the information relating to the current satellite position. Object Name and Revolution At the top of the box the name of the satellite is shown along with the current revolution number. Map The center of the box contains the mercator projection world map which is where the satellite position is shown graphically. Each computed satellite position is shown on the map as a yellow dot. As more and more points are plotted, a ground track will eventually be evident on the map. Latitude and longitude lines are shown on the map for reference purposes. Help Screen When the F1 help key is pressed the world map area is used by the PC-TRACK ASSISTANT to display the various help screens. This is the very same help system used in other parts of the program. When you are done with the help system, press ESC and the world map will be restored as it was when help was requested. Position and Altitude Finally the bottom of the screen shows numerically the current satellite position in latitude and longitude. Also shown is the current altitude of the satellite in miles. STATION BOX Next to the object box is the STATION BOX. This box displays information which is related to the observation point, including the current relationship between the observation point and the current satellite position. Observation Point Info At the top of the box is the information describing the observation point, specifically the Description, Latitude, Longitude, Height, Time Zone, and Minimum Elevation for that point. Azimuth/Elevation Chart Below the observation point info is a chart which graphically shows the current relationship between the observation point and the object. This chart is read as follows: A point will be placed on the chart based on the current azimuth (bearing) and elevation needed to point an antenna at the object from the observation point. The distance from the center of the chart represents the current elevation. The farther the point is from the center, the lower the elevation. This is indicated by the numbers shown along the horizontal line on the chart. The center represents 90 degrees elevation or directly overhead. The angular position from the vertical line represents the azimuth from the observation point to the satellite. The azimuths are numbered clockwise around the outside of the outermost circle drawn on the chart. Zero degrees azimuth is true north. Azimuth, Elevation, and Slant Range Below the Azimuth/Elevation chart is a box which numerically show the observation point/object relationship. In this box the Azimuth, Elevation and Slant Range are shown. The slant range is the straight line distance from the observation point to the satellite at its current position. This figure is shown in miles. HELP BOX The HELP BOX is a handy reminder of the various key commands available for use during the tracking process. This is a summary of the commands, for details press the F1 key. FUNCTION KEYS There are several function keys set up to control various features of PC- TRACK which affect the tracking process. They are described as follows... F1 - Help This is the key which brings up the PC-TRACK ASSISTANT as described earlier. It functions exactly as it does anywhere else in the program except the help screens show in the area of the world map. Once you exit the help system, the world map is restored to its original condition before help began. F2 - Real Time / Fast Track This key controls the tracking mode of PC-TRACK. When tracking first begins, it is in the REAL TIME TRACK mode. This means the position displayed represents the actual satellite position according to the time set in the computer (DOS time). The displays will be updated at the time interval shown in the TIME INTERVAL BOX (fixed to 1 second). Pressing the F2 key changes this to the FAST TRACK mode. This mode ignores the clock in the computer and simply computes and displays the satellite positions as fast as it can. The time between each point computed is determined by the time interval shown in the TIME INTERVAL box. This time interval is changeable according to the procedures shown below. The F2 key acts as a "toggle". This means that if you press it once, the mode changes to FAST TRACK. When you press it again, the mode changes back to REAL TIME TRACK. Pressing it again changes the mode again to FAST TRACK, etc. F3 - Pause Tracking This key may be pressed at any time during tracking to "freeze" the display. This stops all computations and simply waits for the F3 key to be pressed again. Once it is pressed again, normal tracking resumes. While in the pause mode, you may make changes to the time increment (described below), turn the printer on or off, and select Real Time or Fast Track mode. F4 - Enable Printer This key enables output to be sent to the printer during the tracking process. The amount of data sent to the printer is determined by your response to the prompt during the SELECT process just before tracking began, either all data or just points with elevations above the minimum elevation. The F4 key operates as a toggle just as the F2 and F3 keys. If printing is enabled, just press F4 again to turn it off. F5 - Redraw Screen The F5 key simply redraws the World Map and the Azimuth/Elevation chart to remove clutter from extended tracking. CTRL F1-F5 - Decrease Time Interval By pressing and holding the control key (CTRL) and at the same time pressing either F1, F2, F3, F4, or F5 the time interval may be decreased. The following chart shows how each key affects the time interval. HR MN SEC TIME INCREMENT 00:00:00 ■ ■■ ■■ │ ││ ││ CTRL F1 ■─┘ ││ ││ CTRL F2 ■───┘│ ││ CTRL F3 ■────┘ ││ CTRL F4 ■──────┘│ CTRL F5 ■───────┘ Please notice that the time interval can be made to go negative. This is a feature of PC-TRACK which allows you to track backwards in time to enable you to get to a specific point in time for analysis. ALT F1-F5 - Increase Time Interval By pressing and holding the alt key (ALT) and at the same time pressing either F1, F2, F3, F4, or F5 the time interval may be increased. The following chart shows how each key affects the time interval. HR MN SEC TIME INCREMENT 00:00:00 ■ ■■ ■■ │ ││ ││ ALT F1 ■─┘ ││ ││ ALT F2 ■───┘│ ││ ALT F3 ■────┘ ││ ALT F4 ■──────┘│ ALT F5 ■───────┘ >>> CONFIGURATION <<< This module allows you to modify certain things about the program which affect the way the program operates. The things you can change are text screen colors, printer control codes, and the data file subdirectory. CONFIGURE SCREEN This option allows you to easily change the colors you see on the text screen displays. This way you can get the screen displays to look the way you want. This also makes it easy to adjust displays on monochrome monitors. You are able to see the effects of changes on the screen while you make them. You can make changes to both the background and text colors with simple key strokes. Here's how to do it... Information is displayed on the screen using 7 different categories for the text and background colors... - NORMAL - HIGHLIGHTED - DATA ENTRY - TITLE - SCREEN COLOR - SHADOW COLOR (Background only) Only the combinations used in PC-TRACK are shown. The colors for both the background and text colors can be selected for each of these categories. Selecting Text Color Category Using the Left and Right arrow keys selects the category for text color changes. The currently selected category is shown by a down arrow pointing to it along the top of the matrix. Select Background Category Use the Up and Down arrow keys to select the category for background color changes. The currently selected category is shown by a right arrow pointing to it along the left side of the matrix. Change Text Color (F5) Pressing this key changes the color of the currently selected text category. There are 16 colors to choose from. Change Background Color (F6) Pressing this key changes the color of the currently selected background category. There are 2 sets of 8 identical colors. One set causes the text to be non-blinking while the other causes blinking text. CONFIGURE SYSTEM This option allows you to change the control codes sent to your printer to make it print the PC-TRACK reports correctly. It also allows you to define where PC-TRACK looks on your disk to find the files it needs to operate with. Printer Codes Printer codes are sequences of special control characters sent to your printer. PC-TRACK displays and accepts them from you as the decimal equivalents of each control character separated by a slash (/). For example, the ESC character has a decimal value of 27 so it is shown on the screen that way. Notice each print command has a code sequence to turn it on and one to turn it off. Some codes do not need to be turned off, so those portions are left blank. Some printers may not be capable of printing certain features shown on the screen, in that case, leave the CODE TO TURN ON blank for that feature. You have up to 20 characters to define the turn-on or turn-off codes, including the slashes. You may move the cursor around on the screen to the desired code sequence by using the arrow keys or just pressing RETURN. Data Path This line tells PC-TRACK what disk drive and what directories and subdirectory on that disk to use as the storage area for the data files it uses. This line of text will be in the form of an MS-DOS path name. If you just want to tell PC-TRACK to use the B drive, just enter "B:" here. If you have PC-TRACK on your hard disk and it is the C drive and you have a special subdirectory called "\PCT\DATA", then you would enter "C:\PCT\DATA\" on this line. (Please make sure to add the final backslash "\" to the path entered.) APPENDIX A OBTAINING SATELLITE INFORMATION The information required by PC-TRACK can be obtained by requesting the "NASA PREDICTION BULLETIN" or the "TWO LINE ORBITAL ELEMENTS" for each of the objects desired, referenced by CATALOG NUMBER from: PROJECT OPERATIONS BRANCH (CODE 513) NASA/GODDARD SPACE FLIGHT CENTER GREENBELT, MD. 20771 You may also request a package of prediction bulletins for certain categories of objects such as weather or amateur radio satellites rather than by individual CATALOG NUMBERS. If you do not know the CATALOG NUMBER of the satellites you wish to order data for, you can request the current "SATELLITE SITUATION REPORT". There is no charge for this document and it can also be obtained from the above address. The Satellite Situation Report lists almost every object currently in orbit. Each object is cataloged by the International Designation and by Catalog number. It also lists the name, launch date, orbital period in minutes, inclination, apogee, perigee, and transmitting frequency. By using this document you can determine the catalog numbers of the objects you wish to track with PC-TRACK. APPENDIX B HOW TO USE THE ORBITAL DATA FROM NASA The data required by PC-TRACK is contained in the Two Line Orbital Elements. As described above, these elements are a part of the Nasa Prediction Bulletin described in Appendix A. The following is an example of the format of the elements received from Nasa. The Two Line Orbital Elements look like this when you get them from Nasa... 1 13923U 83153.41230725 0.00000215 11423-3 0 376 2 13923 98.7483 183.1938 0017844 74.4610 285.8536 14.22303248 9340 Here are the pieces that PC-TRACK requires, broken out for you... LINE 1 EPOCH YEAR PERIOD DECAY ■■ RATE │ ■■ ■─────┴──■ 1 13923U 83153.41230725 0.00000215 11423-3 0 376 ■ ■ ■ ■ ■ │ └─────┬────┘ └──────┬──────┘ │ ■ │ │ EPOCH DAY.FRACTION ■ │ NOT USED └───■ CATALOG NUMBER (ignore letter) LINE 2 CATALOG NUMBER ■ │ INCLINATION ECCENTRICITY MEAN ANOMALY │ ■ ■ ■ │ │ RIGHT ASC. │ ARGUMENT │ MEAN MOTION ┌───┤ ┌────┴┐ OF NODE │ OF PERIGEE │ ■ ■ ■ ■ ■ ■────┴─■ ■─────┘ ■────┴■ ■─────┴■ ■────┴────■ 2 13923 98.7483 183.1938 0017844 74.4610 285.8536 14.22603248 9340 ■┬─■ │ REVOLUTION NUMBER■──┘ AT EPOCH NOTICE THAT THERE IS NO DECIMAL POINT PRINTED FOR ECCENTRICITY. THE DECIMAL POINT GOES IN FRONT OF THE NUMBER. FOR EXAMPLE, THE NUMBER SHOWN ABOVE FOR ECCENTRICITY WOULD BE ENTERED AS .0017844. APPENDIX F G L O S S A R Y The following are some terms used in the satellite tracking business and are described in layman's terms. APOGEE The point in a satellite's orbit farthest from the Earth's center. ARGUMENT OF PERIGEE The angular distance measured in the orbit plane, in the direction of motion of the satellite, from the point of intersection of the orbit and equatorial planes, to the perigee point. The perigee point is the point in the orbit where the satellite is closest to the earth's surface. ASCENDING NODE Point at which the satellite crosses the equatorial plane from the southern hemisphere to the northern hemisphere. (See also RIGHT ASCENSION OF THE ASCENDING NODE.) AZIMUTH The angle measured in the plane of the horizon from true North clockwise to the vertical plane through the satellite. CATALOG NUMBER A 5 digit number assigned to a cataloged orbiting object. This number may be found in the Nasa Satellite Situation Report and on the Nasa Prediction Bulletins. COORDINATED UNIVERSAL TIME (UTC) Also known as Greenwich Mean Time (GMT). Local time at zero degrees longitude at the Greenwich Observatory, England. Uses 24 hour clock, ie. 2:00 pm is 1400 hrs. CULMINATION The point at which a satellite reaches its highest position or elevation in the sky relative to an observer. (Also known as the Closest Point of Approach) DECLINATION The angular distance from the equator to the satellite measured positive north and negative south. DRAG The force exerted on a satellite by its passage through the atmosphere of the Earth, acting to slow the satellite down. ECCENTRICITY The degree of flattening of the orbit or its departure from a circle. The greater the eccentricity, the more elliptical the orbit is. ELEMENT SET See ORBITAL ELEMENTS. EPHEMERIS A tabulation of a series of points which define the position and motion of a satellite. EPOCH A specific time and date which is used as a point of reference; the time at which an element set for a satellite was last updated. EQUATORIAL PLANE An imaginary plane running through the center of the earth and the Earth's equator. INCLINATION The angle between the orbit plane and the Earth's equatorial plane, measured counter-clockwise. 0 (zero) degrees inclination would describe a satellite orbiting in the same direction as the Earth's rotation directly above the equator (orbit plane = equatorial plane). 90 degrees inclination would have the satellite orbiting directly over both poles of the earth (orbit plane displaced 90 degrees from the equatorial plane). An inclination of 180 degrees would have the satellite orbiting again directly over the equator, but in the opposite direction of the Earth's rotation. INTERNATIONAL DESIGNATOR An internationally agreed upon naming convention for satellites. Contains the last two digits of the launch year, the launch number of the year and the piece of the launch, ie. A-indicates payload, B-the rocket booster, or second payload, etc. LATITUDE Also called the geodetic latitude. the angle between the perpendicular to the Earth's surface (plane of the horizon) at a location and the equatorial plane of the earth. LONGITUDE The angular distance from the Greenwich (zero degree) meridian, along the equator. This can is measured either east or west to the 180th meridian (180 degrees) or 0 to 360 degrees west. For example, Ohio includes 85 degrees west longitude, while India includes 85 degrees east longitude. But 85 degrees east longitude could also be measured as 275 degrees west longitude. MEAN ANOMALY Angular distance measured in the orbit plane, in the direction of motion, from the perigee point to the satellite's mean position. MEAN MOTION The number of complete revolutions a satellite makes in a given unit of time, usually measured in revolutions per day. (see also DECAY) NASA PREDICTION BULLETINS Report published by Nasa Goddard Space Flight Center providing latest orbital information on a particular satellite. This report gives information in 3 parts: 1) two line orbital elements, 2) Longitude of the South to North equatorial crossings, and 3) longitude and heights of the satellite crossings for other latitudes (besides the 0 degree latitude shown in part two). ORBITAL ELEMENTS Also called Classical Elements, Satellite Elements, Element Set, etc. Includes the catalog Number; epoch year, day, and fraction of day; period decay rate; argument of perigee, inclination, eccentricity; right ascension of ascending node; mean anomaly; mean motion; revolution number at epoch; and element set number. This data is contained in the TWO LINE ORBITAL ELEMENTS provided by Nasa in the Nasa Prediction Bulletin. PERIOD DECAY RATE Also known as Decay. This is the tendency of a satellite to lose orbital velocity due to the influence of atmospheric drag and gravitational forces. A decaying object eventually impacts with the surface of the Earth or burns up in the atmosphere. This parameter directly affects the satellite's MEAN MOTION. This is measured in various ways but PC-TRACK, the Nasa Prediction Bulletins and the Two Line Orbital Elements use revolutions per day per day. PERIGEE - The point in the satellite's orbit where it is closest to the surface of the earth. POSIGRADE ORBIT Satellite motion which is in the same direction as the rotation of the Earth. RETROGRADE ORBIT Satellite motion which is opposite in direction to the rotation of the Earth. REVOLUTION NUMBER AT EPOCH The number of revolutions or ascending node passages that a satellite has completed at the time (epoch) of the element set since it was launched. The orbit number from launch to the first ascending node is designated zero, thereafter the number increases by one at each ascending node. RIGHT ASCENSION OF THE ASCENDING NODE The angular distance from the vernal equinox measured eastward in the equatorial plane to the point of intersection of the orbit plane where the satellite crosses the equatorial plane from south to north. SATELLITE SITUATION REPORT A report published by Nasa Goddard Space Flight Center listing all known man- made Earth orbiting objects. This report lists the Catalog Number, International Designator, Name, Country of origin, launch date, orbital period, inclination, beacon frequency, and status (orbiting or decayed). TWO LINE ORBITAL ELEMENTS See ORBITAL ELEMENTS. VERNAL EQUINOX Also known as the first point of Aries, being the point where the Sun crosses the Earth's equator going from south to north in the spring. This point in space is essentially fixed and represents the reference axis of a coordinate system used extensively in Astronomy and Astrodynamics.