World of Ham Radio 1997

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Text File | 1997-02-01 | 18KB | 309 lines

STSORBIT PLUS Revision History ------------------------------ Each released version of STSPLUS uses a four digit revision code such as 9650. The first two digits indicate the year and the second two digits indicate the week of the year. In some cases, an additional letter suffix is added to distinguish changes occurring within the same week or to identify special versions. A partial week at the beginning or end of the year is counted as a full week. Using this method, a year will typically have 53 weeks although it is possible to have 54 weeks in a leap year (1972 is an example). The current year-week revision code is shown on the Julian Date display, Display Mode 7, in my program ASTROCLK. This file records the revision history of program STSPLUS through all of the minor twists and turns that usually accompany the evolution of such a complex program. It illustrates the tortuous process of maintaining and refining a program as ideas and problems are reported from every quarter. These notes may also be helpful to users who are upgrading from one version to another to find out what has changed. David H. Ransom, Jr. e-mail: rans7500@spacelink.msfc.nasa.gov Version 9650 -- December 1996 ----------------------------- -This is a FEATURES UPGRADE adding "Night Vision" red screen capability, Location Map mode at user-specified coordinates, as well as correcting several minor bugs. -With the increased availability of color laptop computers, many users are taking STSPLUS outside at night so that they can both watch satellites and continue to track using STSPLUS. Unfortunately, the bright, multi-color screen tends to reduce night vision adaptation. I have therefore added the ALR-R command (for "RED") in the Main Menu and when the map is displayed. When "Night Vision" is enabled with ALT-R, all colors are changed to either RED or LIGHT RED. Press ALT-R again to return to standard colors. ALT-R is only effective at the Main Menu and while the map is displayed. The "Night Vision" mode is NOT saved and must be re-enabled each time STSPLUS is executed. Users may find that temporarily disabling some screen features, such as rivers or location labels, may make the red screen less "cluttered" and easier to read. -Set User Definable Colors (F10+F9 from the Main Menu) always uses normal colors even if Night Vision mode is enabled. -At the request of several geography teachers, I have added the capability to specify the coordinates of the center of the orthographic map in the Location Map mode. To enable this feature, select the orthographic projection ("O" with the map displayed), then select Location Map mode ("L"), then press the slash ("/") key. STSPLUS will request the desired map center coordinates. Enter the latitude and longitude in degrees (and optional decimal fraction) as prompted. A RED CROSSHAIR marks the map center. (For example, enter -17.5 and -150 to center the map near Papeete, Tahiti.) All of the normal zoom features (PgUp, PgDn, Home, and End) are operational and, in addition, the arrow keys (UP, DOWN, LEFT and RIGHT) will shift the map center by the current GRID spacing in the direction selected. Press "L" to return to the normal Location Map centered on the users primary or secondary location. -Added additional code for proper operation past 1999. Prior versions did not handle Rev Codes in century 2000 (0001, 0101, etc.) correctly and failed. -Corrected a minor bug which caused the screen to scroll when in TARGET mode on the world map with statute miles selected as the units. Problem was an extra SPACE after "mph" near the bottom of the screen when the primary and target spacecraft were relatively close to each other. (Careless error, my apologies ...) -Corrected a minor bug with the South Atlantic Anomaly ("SAA") color when the "/M" command line option is used. The SAA was still in color. -Trapped low memory error (BASIC ERROR = 7) when attempting to execute the SHELL command (F9 from the Main Menu). STSPLUS now displays an appropriate error message and returns to the Main Menu. -The Night Vision feature was available as Beta Test Version 9644 which was given limited distribution via my BBS. Version 9643 -- October 1996 ---------------------------- -This is a MAINTENANCE UPDATE adding a feature for amateur radio tracking and correcting a minor bug introduced in Version 9642. -A complementary (inverted) Azimuth/Elevation tracking feature has been implemented to accommodate a hardware limitation in most two-axis antenna drives. The most popular amateur antenna rotors provide a full 360 degrees of azimuth coverage but have a "stop" point that does not allow "through" tracking; this "stop" is usually at North or South. If the stop is encountered in the middle of a satellite pass, tracking must cease while the antenna is rotated through 360 degrees, a process that can take up to one minute and is a significant portion of a typical 8 to 10 minute Mir or Space Shuttle pass. The "stop" limitation can also be at least an inconvenience for other, longer passes. -Complementary Azimuth and Elevation are calculated as follows: CAz = (Az + 180) MOD 360 CEl = El - 180 -Complementary Azimuth/Elevation tracking may be enabled by using F10 from the Main Menu and toggling F4 until the SECOND E/A appears OR by pressing F10 while the map is displayed until "CEl" and "CAz" are displayed as the satellite coordinate labels. These special labels appear in YELLOW rather than the usual cyan in order to alert the user. -A minor bug related to the change in coprocessor detection was discovered in Version 9642 by Mike Goen at White Sands, NM. When a shuttle was tracked prior to launch with launch time and date enabled, secondary satellites did not display the square symbol but only the single position pixel. The problem has been corrected. Thanks, Mike! Version 9642 -- October 1996 ---------------------------- -This is a MAINTENANCE RELEASE correcting an annoying bug with Windows NT and updating the state vector output data formats to regain compatibility with Ken Ernandes' VEC2TLE along with several other relatively minor changes. -WinNT/Win95 threaten to converge and take over the PC world. After some months, I finally located the clock problem for Windows NT and removed the call to system hardware (to check on processor type and the presence of a math coprocessor). This call was causing the STSPLUS local clock (either UTC or local time depending upon the setup) to always start at 00:00:00 in Windows NT. Other operating systems were not affected. Instead, I now use a simple BIOS equipment call (INT 11H) to determine the presence or absence of the math coprocessor, a call which occasionally yielded incorrect information on older computers. Unfortunately, the BIOS call does NOT identify the processor type, so that information is lost to STSPLUS for good. Special thanks to Paul Gabriel for providing the crucial clue to solving this annoying problem for WinNT users! -By popular request, pressing the "R" key while the map is displayed will now command an immediate redraw of the map. This avoids returning to the Main Menu just to update the map. -In order to use units more easily understood by non-technical users, I changed the units of relative velocity for the TARGET satellite when statute miles ("sm") are selected from statute miles per second or feet per second to statute miles per hour ("mph"). Press F9 while the map is displayed to select desired units of measure. -In order to regain compatibility with Ken Ernandes' VEC2TLE which seems to have been lost some versions back, apparently, I have modified the Data Output format for Data Modes 4, 14, 24, 7, 17, and 27 (labeled data, equivalent to VEC2TLE's .VIF format) to add an initial data line to each state vector labeled "Vector format" as shown in the following example: STSORBIT PLUS Data Output to STSPLUS.LOG, Data = 7 Vector format = 7 <=== New Data Line Satellite Name: MIR Space Station Catalog Number: 16609 86017A Epoch Date/Time: 96284.68473379630 10 OCT 1996 16:26:01.000 UTC <=== Changed Format ECI X: 289.76005663123 km Y: -6582.91140457084 km Z: 1521.48769778595 km Xdot: 4.82433247335 km/sec Ydot: 1.54561448538 km/sec Zdot: 5.77061241671 km/sec Ndot/2 (Drag): 0.00001710000 Nndot/6: 0.00000000000 B-Star: 0.00002510100 ElSet #: 705.00000000000 Rev @ Epoch: 60805.04617255837 Note that the "plain language" date has been changed from "mm/dd/yyyy" to "dd MMM yyyy" for clarity. The two changes are marked with "<===" in the example. Each state vector is followed by a blank line for clarity. The example above is for Data Mode 7; the same changes have been made for Data Modes 4, 14, 24, 17 and 27. -When evaluating TARGET relative range and velocity, users should note that during rendezvous operations the orbits of the two satellites may NOT be closely synchronized and the approaching satellite's orbit will often have a significant eccentricity. This can make the range and relative velocity increase and decrease over a large range of values! Velocity in particular can have both positive and negative values as the range increases and decreases during the course of an orbit. -Corrected a minor bug which prevented Target Relative Velocity from being displayed when using the Motion Map. Version 9637 -- September 1996 ------------------------------ -This is a MAINTENANCE UPDATE to correct a problem with certain COUNTRY CODES outside the United States. -Version 9635 locked up when drawing the orthographic map because of a problem interpreting the NORAD-style date ("yyddd.dddddd") when the COUNTRY CODE substituted a comma (",") for the US-style period (".") for the decimal point. The problem has been corrected and the appropriate decimal point will now be displayed in the NORAD-style date at the upper right of the data portion of the orthographic display. -No other changes were made in either program code or documentation. Version 9635 -- August 1996 --------------------------- -This is a MAINTENANCE UPDATE, incorporating several minor improvements. -STSPLUS passed its 5th birthday in August, 1996! For those who have asked, I will continue to support and enhance STSPLUS as a DOS-based program at least through the balance of 1996. A Win95/WinNT version, if that ever happens, likely will not appear prior to 1997; the conversion to Windows requires a complete rewrite of the program and documentation, currently some 2MB of code and text. Even if a Windows version does appear, I will continue to support the DOS version for some years. -Changed the code which reads TLEs to automatically skip blank lines. The code was updated both for primary satellite input (filename plus satellite name) and for TLE updates (filename plus "&"). Several users reported problems with TLE files obtained from the Internet which were double spaced; this modification allows the direct use of files with multiple interspersed blank lines throughout the TLE file. -Improved detection of non-DOS TLE files for automatic conversion to DOS line termination format. STSPLUS now detects CR-CR and LF-LF and forces conversion in those cases, as well as using a more robust algorithm to detect standard UNIX and MAC formats. -Added code so that F3 (Pass Predictions) from the Main Menu may be used without first displaying the satellite on the map. -Corrected the "NORAD-style" date display ("yyddd.dddddd") for correct operation at year 2000 and beyond. The format for years beyond 1999 is "00001.123456" (for 01 January 2000) where the year portion is the last two digits of the 4-digit year. The new format will be valid through the year 2049. Years 50 through 99 assume century 19 and years 00 through 49 assume century 20. (Since I would be 114 years old in 2050, someone else can worry about 2050 and beyond!) -Added statute miles ("sm") to Perigee and Apogee calculated values displayed with ALT-F1 from the Main Menu. As displayed, Perigee and Apogee are GEOCENTRIC values. All orbital data are calculated at the Epoch of the TLEs. -Repaired islands in Northern Canada (again) for proper color in orthographic projection. Hopefully I got it right this time ... -Added "SAA" label to South Atlantic Anomaly. -Updated internal NASA/DOD Tracking Station list per Dave Simonson, DOD C- Band Radar Network. The external Tracking Station file, STSPLUS.TRK, has also been updated. -Corrected ascent profile to start at typical Pad 39 elevation. Prior versions showed actual pad elevation prior to launch then reverted briefly to zero at launch. -Automatic map redraw interval prior to shuttle launch has been increased from 15 minutes to 30 minutes. Version 9615 -- April 1996 -------------------------- -This is a MAINTENANCE UPDATE, incorporating several significant enhancements and repairing several minor bugs. -In response to several inquiries, processing times for STSPLUS have increased for current versions due to improved accuracy and complexity, as well as added features. These improvements have been implemented, in part, because of the much greater processing power and speed of current systems. Delays will be more apparent on older systems with 386 and slower 486 processors. ** IMPORTANT NOTE ** Users are reminded that for most DOS and Windows 3.1 systems, a "vanilla" system (configured without a memory manager) will execute MUCH faster; computation times for Visible Pass Predictions, for example, are FOUR TIMES faster with the "vanilla" configuration on a typical Pentium system. The standard "MS-DOS Prompt" configuration for Windows 95 does not include a memory manager and will execute at high speed. -With widespread availability of TLEs on the Internet, many users are now receiving TLEs via these sources. Unfortunately, many Internet systems use UNIX servers and the TLE files are often reformatted with LF-only line termination which causes most DOS programs to fail. STSPLUS has now been modified to test TLE files and, if UNIX or MAC format is detected, to automatically convert the file to DOS format. During file processing (F2 from the Main Menu), the following message is displayed while this conversion is being performed: UNIX.TLE is in UNIX/MAC format and is being converted! Please wait ... The original UNIX/MAC file ("UNIX.TLE" in the example above) is replaced by the new DOS file and the original file is deleted. Normal operation of STSPLUS then resumes. -The Visible Pass Prediction code has been optimized for speed. Calculation times have been improved by 20% to 30% and time resolution has been slightly decreased. Minor differences in data may be observed when compared to prior versions. -Prompted by the re-entry of the Chinese spy satellite (#22870) in early March of 1996, I have changed the code used to detect possible orbital decay. STSPLUS now calculates the perigee at Epoch and displays a warning message if the perigee is less than 75 nautical miles. The user may press ENTER to return to the Main Menu or may press ESC to proceed with orbital calculations. Once a satellite's orbital altitude decays to below about 70 nautical miles (130 kilometers), re-entry may have occurred or will occur very soon thereafter. NOTE: The calculations may fail with a BASIC Error if the satellite has already decayed. -Added data for Perigee and Apogee to that shown using ALT-F1 from the Main Menu. Data are calculated using the orbital data as of Epoch. Also repaired a BASIC Error when using this feature when a launch date and time had not been specified for the satellite. -Corrected a bug with the Duration of Line-of-Sight passes when the Minimum Horizon angle was set to zero degrees. STSPLUS generated inaccurate times, sometimes by tens of hours. Thanks to Josh Willims for spotting the bug! -In order to display a "reasonable" South Atlantic Anomaly when the Space Shuttle is on the launch pad and during ascent phase, the SAA is forced to use a minimum altitude of 75 nautical miles. -Yet another COUNTRY CODE bug has surfaced, this time in file STSPLUS.OBS which is written by STSPLUS for use by Kelso's program TRAKSTAR. In this case, the decimal point in local latitude and longitude were automatically replaced by commas (in spite of a FORMAT statement that explicitly used the period!), causing TRAKSTAR to fail. The code has been rewritten. Thanks to Arve Fager in Sweden for reporting the problem! -Modified automatic map redrawing in rectangular projections so that the map will not be redrawn when AUTO REDRAW is enabled ("A" displayed at upper right, press TAB key with map displayed to enable/disable AUTO MAP REDRAW) until the current map has been displayed for at least 90 seconds. Thanks to Les Putnam for the reminders on this annoying bug! -Added local station latitude (degrees), longitude (degrees), and elevation (meters) to Pass Prediction data output header section. -Some lakes and rivers still slipped through in the orthographic projection when RIVERS were disabled. Thanks to Ed Toomey for spotting them! -Various minor cosmetic changes. -A pre-release of this update, Version 9614, included most changes EXCEPT the automatic conversion of TLE files to DOS format.