Monster Media 1994 #1

home *** CD-ROM | disk | FTP | other *** search

/ Monster Media 1994 #1 / monster.zip / monster / HAM / SOP9414A.ZIP / STSPLUS.NEW < prev next >

Wrap

Text File | 1994-03-28 | 35KB | 608 lines

STSORBIT PLUS Revision History ------------------------------ Each released version of STSPLUS uses a four digit revision code such as 9414. 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. Version 9414 -- March 1994 -------------------------- -This is a MAJOR UPGRADE, adding new features for satellite communications and amateur radio, user-definable map colors for certain map features, improving RA/DEC coordinates, and incorporating several bug fixes. -See also the notes below for Version 9406 (not released publicly). ENHANCEMENTS FOR SATELLITE COMMUNICATIONS AND AMATEUR RADIO: ------------------------------------------------------------ -By popular request and with the assistance of Ken Ernandes, N2WWD, I have added Doppler shift calculations for uplink and downlink frequencies. The calculated uplink (XMIT) and downlink (RECV) frequencies have been tested in full duplex with RS-10 and yield excellent results. The Doppler shift calculations are available in orthographic projections ONLY for this release. See the text for complete discussion. -The satellite NORAD Number, UPLINK and DOWNLINK frequencies (referenced to the satellite), and the transponder mode are specified in file STSPLUS.FRQ in that order, separated by commas and without any leading or trailing spaces. A sample file might include: 00000,100,100,1 (Default values if sat # not found) 18129,145.8900,29.3900,1 (Parameters for NORAD #18129) --+-- ----+--- ---+--- + | | | | | | | +-- Transponder Mode: 1 = NORMAL | | | -1 = INVERTED | | | | | +------- DownLink Center Frequency (MHz) | | | +--------------- UpLink Center Frequency (MHz) | +----------------------- Satellite NORAD Number The first sample line shows the "00000" entry which determines the default parameters if the satellite is NOT included in file STSPLUS.FRQ. This should be the FIRST LINE in file STSPLUS.FRQ. The second line gives real parameters for a specific satellite; the frequencies shown select the Mode A voice passband for Radio Sputnik 10 (RS-10, piggybacked on COSMOS 1861, NORAD #18129). The uplink and downlink frequencies should not exceed 99000.0000 MHz to avoid an overflow condition on the display. -File STSPLUS.FRQ may be created or edited with any ASCII editor; word processor users, use the "non-document" mode. Note that only minimum error checking is performed and the user must observe the required format exactly for each line in the file. -The Doppler shift calculations replace the TDRS and Sun AOS/LOS data in the data block to the right of the orthographic map. To enable display of these frequencies, press F8 while the map is displayed; to return to the AOS/LOS calculations, press F8 again while the map is displayed. F8 is NOT active when in PAUSE mode. The following example illustrates the display as a satellite approaches the ground station (using 1000 MHZ for both frequencies to show the relative transmit and receive ratios): UpLink: 1000.0000 Uplink frequency received by satellite XMIT: 999.9761 TRANSMIT frequency at ground station DnLink: 1000.0000 Downlink frequency xmitted by satellite RECV: 1000.0239 RECEIVE frequency at ground station The XMIT and RECV frequencies will be shown in color on EGA/VGA color monitors: RED Satellite is below receiver's horizon YELLOW Satellite is 5 degrees or less above receiver's horizon GREEN Satellite is 5 degrees or more above receiver's horizon Transmissions will not normally be possible when RED is shown. Transmissions MAY be possible when YELLOW is shown. Transmissions should be practical when GREEN is shown provided the ground station has a clear horizon in the direction of the satellite. -STSPLUS includes a "fine tuning" feature for the uplink and downlink frequencies. While in the Doppler shift calculation mode, the following keys have a different function from the normal map modes: UP Arrow Increase RECV frequency by 100 Hz DOWN Arrow Decrease RECV frequency by 100 Hz PgUp Increase RECV frequency by 1 KHz PgDn Decrease RECV frequency by 1 KHz Home Restore Uplink and DnLink frequencies to those read in from file STSPLUS.FRQ End (not used) If the satellite transponder is NORMAL, the XMIT frequency will be increased or decreased by the same amount as the RECV frequency. If the satellite transponder is INVERTED, the amount of change in the XMIT frequency will be the same magnitude but in the opposite direction as the change to the RECV frequency. OTHER SOFTWARE ENHANCEMENTS AND CHANGES IN THIS RELEASE: -------------------------------------------------------- -In response to numerous user requests, the colors for certain map features are now user-definable. The assignable features are: Local Station circle of visibility Isocontour circles in Location and Tracking Station modes Tracking Station circles of visibility From the Main Menu, use F10+F9 to set these colors. The new colors will be saved in file STSPLUS.INI for future use. To those users who want to change EVERYTHING, my response is: a) that's a non-trivial programming exercise, and b) I've spent considerable time designing the program to have a certain "look and feel" which I wish to retain. - The Program Features and Options menu has been changed. Function Key F9 is now used for User-Definable Colors (above) and not for setting the UTC Offset and Daylight Flag. Use F8+F10 from the Main Menu to set the UTC Offset and Daylight Flag. -Users are reminded that STSPLUS expects ground station coordinates (latitude and longitude) in the geodetic coordinate system, as commonly used on maps (WGS-72 System). Ground station altitude (elevation above Mean Sea Level) is expected in METERS; if a ground station is significantly above Mean Sea Level, accuracy will be substantially improved if an accurate altitude is used. Many cities in file STSPLUS.CTY have ZERO given as the altitude if no altitude was available in the source(s) used for preparation of the file. The same comments apply to Tracking Stations in file STSPLUS.TRK. -The coordinates for Right Ascension and Declination were incorrect in prior versions. The ground station's GEODETIC latitude instead of the GEOCENTRIC latitude was used in the calculations. The error was greatest (especially the Declination) for ground stations in mid-latitudes as a satellite approached local zenith. Thanks to Alan Nutley of Australia for putting me on the track of this one! -Local horizon coordinates were also affected by the latitude error. The typical error near maximum was one or two degrees in altitude (elevation). -The keyboard response time has been improved; except when the map is actually being drawn, response is immediate instead of waiting for the next second. In the Doppler Shift Mode, the arrow keys and PgUp and PgDn may be held down to repeat. During rapid key repeats, map and data updates may be deferred; waiting for a second will allow the map and data to be updated. -The primary satellite's circle of visibility did not display on the World Map when the Motion Map (Dual-Page EGA Mode) was enabled. This has been corrected. Thanks to Todd Sherman for reporting the bug. -Corrected a problem which caused BASIC ERROR 6 on restart when the SHELL TO DOS (F9 from the Main Menu) was used and the program was in orthographic projection. -Various minor bug fixes and cosmetic changes. -Versions 9412 and 9413 were BETA VERSIONS released on a limited basis. -Special thanks to Ken Ernandes, N2WWD, for his assistance and testing of the satellite communications and amateur radio features! Version 9406 -- February 1994 ----------------------------- -This version was for Beta Test only and was not released publicly. -Several users have reported that file STSPLUS.INI sometimes became corrupt and I have (finally) found and corrected the problem. An array index was overrunning the bounds of the array and overwriting other data in SHARED COMMON. This usually only affected the data in secondary satellites but was potentially more dangerous. The problem also caused some dot colors on the ground track to be incorrect. -When no STSPLUS.INI file is present (or when the UTCOffset is set to -99), the user is automatically asked to set filenames and paths. -In response to quite a number of user requests, I have added the "/SS" command line option to force STSPLUS into a "screen saver" mode. In this mode the program displays the full orthographic globe, ground track and all selected map features but NO DATA at the right. Use ENTER or ESC to return to DOS. -New command line options have been added to control certain display features (especially from batch files). The new feature status is saved in file STSPLUS.INI. +L Include Location and Feature Labels -L Exculde Location and Feature Labels +R Include Rivers and Lakes -R Exclude Rivers and Lakes +T Include Tracking Stations -T Exculde Tracking Stations +V Include Local Circle of Visibility -V Exclude Local Circle of Visibility -Because of problems reported with word processors which add the 8th bit to some characters (and have been used to edit TLE files), I have added code to strip off the 8th bit in Line 0 of TLEs. However, this is not foolproof, and users are cautioned to use ONLY editors which do NOT add the 8th bit and which maintain the "standard" CR/LF at the end of each text line. Version 9405 -- January 1994 ---------------------------- -Version 9405 is a MAINTENANCE UPDATE, correcting a number of relatively minor bugs and updating the documentation to reflect changes in Versions 9403 and 9405. -Rewrote MET calculations to (hopefully) avoid truncation and rounding errors which sometimes caused MET to be one second off. The problem was dependent upon both launch and epoch times. -Added default filenames and paths if UTCFlag is set to -99. (Setting UTCFlag to -99 may be used to distribute STSPLUS.INI files when the ultimate user's time zone is unknown. This procedure forces the user to set the UTC and DAYLIGHT values, and is NOT recommended for the novice!) Filenames and paths should ALWAYS be checked and set if necessary using F7 from the Main Menu whenever upgrading to a new version. -Improved calculation algorithm for "Calculating Orbital Data" phase of program initialization for satellites with mean motion less than 15 and greater than 2. The improvement may only be apparent on slower processors or systems without a math coprocessor. -Corrected a cosmetic bug which caused the time portion of negative MET to appear at the left on the next line in rectangular projection modes. (Missing semicolon!) The following pages have been excerpted from the documentation for Version 9414 and describe the changes related to Satellite Communications and Amateur Radio. Program STSORBIT PLUS Satellite Orbit Simulation Page 56 Satellite Communications and Amateur Radio ------------------------------------------ By now, everyone is familiar with communications satellites. They provide almost instant communications, particularly television, around the globe from their assigned geostationary "parking slots" some 22,300 miles above the surface of the Earth. The concept of the geostationary communications satellite was originated by the science fiction writer Arthur C, Clarke some thirty-odd years ago. Novel and revolutionary at the time, they have become an accepted part of global communications, all but taken for granted by the millions of people who see the images they transmit over vast distances. Glossing over some of the "minor technological details" that make these miracles possible, the communications satellite is relatively easy to use. Because of its geostationary orbit (which matches its orbital velocity with the Earth's rate of rotation), it appears to remain at the same point in the sky. Once properly located, ground terminals may be more or less permanently aimed and that's that. Reliable communications are routine except during the semi-annual Sun blockage periods when the Sun, satellite, and ground terminal are in a direct line with each other and the Sun's powerful radiation overwhelms the signals from the satellite. However, geostationary communications satellites are but one example of the uses for satellite communications. Except for a relatively few passive satellites, each satellite has on board radio transmitters and receivers so that its ground control centers may send commands and receive data; these commands and data provide for the operational control and orbital position and stability of the satellite. Unlike the geostationary communications satellites, these satellites are in orbits which cause them to appear to move rapidly across the sky when viewed from the ground. The typical effective ground speed of the space shuttle, for example, is some 17,500 miles per hour; other satellites in higher orbits move more slowly. Viewed from afar, both the ground station and the satellite are moving rapidly, sometimes toward each other and sometimes away, as a result of the rotation of the Earth and orbital direction/velocity respectively. Since the typical satellite's receiver(s) and transmitter(s) are usually set for fixed frequencies, these high relative velocities cause a problem on the ground known as Doppler Shift. Almost everyone has heard a train whistle as it speeds past; the whistle's pitch is high when first heard, then drops steadily as the train passes. The "true" pitch of the whistle is heard when the train is opposite the listener. While the train is approaching the pitch is shifted to a higher frequency, and as the train recedes the pitch is shifted to a lower frequency. For satellite communications, this effect is increased by the much higher relative velocities involved and it is usually necessary to adjust the transmit and receive frequencies on the ground to compensate for the shift. Stated simply, the ground station must adjust its transmitting frequency such that the shifted frequency as received by the satellite is the exact frequency for which the satellite receiver is set. Similarly, the ground station must adjust its receiver frequency to the shifted frequency at which the satellite's signal will be received. Like the train whistle, the ground station's transmit and receive frequencies are constantly changing as the satellite approaches and then departs from the ground station. As a general rule, no two satellite passes over a ground station have exactly the same geometry and therefore these frequency shift adjustments must be calculated dynamically for each pass. In the special Program STSORBIT PLUS Satellite Orbit Simulation Page 57 case of Frequency Modulation (FM) transmissions using a receiver with Automatic Frequency Control (AFC) and a sufficiently wide receiver AFC bandwidth, no adjustments may be necessary. Given a satellite's orbital paramaters and the appropriate computer software, these data can be calculated in advance of an upcoming pass as well as in real time. Most of the required data are already calculated in satellite tracking software such as STSPLUS. Ken Ernandes, N2WWD, offered his expertise and amateur radio equipment to assist in the implementation and test of Doppler Shift calculations in STSPLUS. The necessary changes and additions to the software were implemented in mid-March 1994 and Ken made a preliminary test using Radio Sputnik 10 (RS-10, a piggybacked transponder on the Russian COSMOS 1861 satellite, NORAD #18129). To our considerable surprise and delight, the very first test was a complete success; although the satellite only reached a maximum of 7 degrees above the ground station's horizon, the transponder signal was heard (rather weak and noisy) on the predicted frequency. Although we both were confident in our mathematical solution to the Doppler shift problem, it is seldom that such calculations turn out to be correct on the first try! Testing and validation continue. STSPLUS' Doppler shift mode of operation may be used for real time communications with any satellite, not just amateur radio transponders, for which orbital data ("2-line elements" or "TLE") are available. For each satellite, the user prepares a preset frequency list in file STSPLUS.FRQ which includes the satellite's NORAD Number, the transmit (XMIT) and receive (RECV) center frequencies, and a special code which is used to select NORMAL or INVERTED satellite transmitter transponders (see below). For satellites with fixed transmit and receive frequencies, that is all that is required; for satellites which receive and transmit over a band of frequencies, such as the passbands of the typical amateur radio repeater transponder, the receive and transmit frequencies may be quickly "tuned" in tandem by fine increments of 100 Hz or coarse increments of 1 KHz over the entire passband. For those who may be interested, the solution of the Doppler shift computations required that the ground station position vector and the satellite position and velocity vectors be calculated using standard transformation algorithms (and the SGP4 Orbital Model for determining the satellite data), then converted to Earth-Fixed Greenwich ("EFG") coordinates, a geocentric intertial coordinate system using the WGS-72 Geodetic Model. From these data the relative velocity and frequency shift ratios are next calculated. These ratios are then applied to the preset transmit and receive center frequencies to yield the shifted frequencies, all of which are then displayed to the user. Provided the computer is equipped with a math coprocessor chip, all data are updated each second. The following is an example of the frequency data displayed as a satellite (RS-10 in the example) approaches the ground station: UpLink: 145.8900 Uplink frequency received by satellite XMIT: 145.8880 TRANSMIT frequency at ground station DnLink: 29.3900 Downlink frequency xmitted by satellite RECV: 29.3904 RECEIVE frequency at ground station The shifted transmit frequency (XMIT) and receive frequency (RECV) are also color coded to indicate the signal status: RED The satellite is below the receiver horizon; communications Program STSORBIT PLUS Satellite Orbit Simulation Page 58 are normally not possible. YELLOW The satellite is from zero to five degrees above the receiver horizon; transmissons MAY be possible. GREEN The satellite is five degrees or more above the receiver horizon; transmissions should be practical if the receiver horizon is clear in the direction of the satellite. The altitude (or elevation) of the satellite above the receiver horizon is usually a good indicator of communications capability. However, transmitter power, receiver sensitivity, antenna structure and orientation, and atmospheric conditions all play a role in making reliable full duplex communications practical. For example, the large antennas used by the DOD C-Band Radar Network, used to track the orbiter and other satellites during ascent and critical maneuvers, typically acquire signal lock when the satellite is between 3 and 4 degrees above the local horizon. A low power amateur radio rig may require that the satellite be from 5 to 8 degrees above the local horizon for reliable communications. To illustrate the role atmospheric conditions may play, the space-based geostationary TDRS (Tracking and Data Relay Satellite) typically acquires signal lock with a target satellite at or near Earth limb (what passes for the "horizon" at the satellite). In addition to the frequency data, the ground station ("STN") times for Acquisition of Signal ("AOS") and Loss of Signal ("LOS"), calculated for the true ground station horizon, are displayed so that the user may quickly determine how soon a pass will begin or how much time remains in a current pass. For ground station to satellite communications, operation is straightforward. The user simply adjusts his transmit ("XMIT") and receive ("RECV") frequencies to those shown by STSPLUS as the satellite passes his location. Since the frequencies required at the satellite are known and do not change, there are no "fine tuning" adjustments required. Compared to a satellite with fixed receive and transmit frequencies, the typical amateur radio satellite transponder (also referred to as a "crossband repeater") presents a slightly more complex situation. The transponder receives signals across a passband of frequencies (20 to 80 KHz are typical bandwidths), then retransmits the received signals across a passband of the same width but centered at a different frequency. The center frequency of the receive and transmit passbands are known in advance but may change from time to time depending upon the transponder mode (CW, voice, digital packet, etc.). The transmit side of the transponder may also operate in either NORMAL or INVERTED mode. That is, for NORMAL mode the transmitted signal is the same frequency above or below the center frequency as is the received signal; for INVERTED mode, the transmitted signal is the same frequency above (below) the transmit center frequency as the received signal is below (above) the receive center frequency. STSPLUS addresses this situation in two ways. First, once the user has received a signal of interest, he uses the PgUp, PgDn, UP, and DOWN keys to "fine tune" the downlink frequency shown by STSPLUS ("RECV") until it matches the actual received frequency. PgUp and PgDn perform "coarse tuning" in increments of 1 KHz, and UP and DOWN perform "fine tuning" in increments of 100 Hz. The response is quite rapid and the fine tuning may usually be performed in no more than several seconds. STSPLUS then makes the necessary calculations to show the required uplink frequency ("XMIT") to permit full duplex communications. The second part of the problem is the Program STSORBIT PLUS Satellite Orbit Simulation Page 59 transponder mode; STSPLUS selects NORMAL or INVERTED transponder mode based upon the mode parameter supplied by the user in file STSPLUS.FRQ: 1 = NORMAL, -1 = INVERTED. Once full duplex communications have been established, remaining "in lock" throughout a pass requires that both parties continually adjust their transmit and receive frequencies to the values displayed by STSPLUS to the extent practical and consistent with the bandwith capabilities of their receivers. Although this may seem a bit daunting at first, the actual rate of change of the frequencies is sufficiently slow that it can easily be managed by the relative novice with a little practice. ******************** * IMPORTANT NOTE * ******************** Experience with communications via amateur ratio satellites such as RS-10 has shown that careful test and calibration of the receiver and transmitter are essential to successful communications. For example, an error or bias of 2 or 3 KHz on the receiver frequency can make the difference between a successful call and a failure. If the receiver or transmitter has a consistent bias, it may be possible to temporarily adjust the values of the center frequencies to compensate for the problem but the best solution, of course, is to have the equipment calibrated and operating correctly. Equally important, the computer clock must be accurately set. Radio time signals such as those broadcast by the National Institute of Standards and Technology (NIST) on WWV are sufficiently accurate for this purpose. The program TIMESET by Peter Petrakis is highly recommended to automatically set the computer clock via the telephone time services of NIST or the U.S. Naval Observatory (USNO). Finally, the frequencies calculated by STSPLUS are no more accurate than the orbital data used. For the typical amateur radio satellite, the orbital data should be no more than a week old for reasonable results. If the satellite is performing orbital maneuvers (as MIR does from time to time), only the most current elements will yield satisfactory results. Sources such as Internet, Celestial BBS, NASA Spacelink BBS, NASA GSFC RBBS, and my own RPV Astronomy BBS offer up-to-date 2-line elements for all or most of the common amateur radio satellites. See the section "Computer Bulletin Board Systems" near the end of this document for current BBS telephone numbers and related information. Since the amateur radio transponders are often "piggybacked" on a primary satellite, the name of the satellite used by these sources may be different from the amateur radio designation. Use the example file STSPLUS.FRQ to check for the NORAD numbers of common amateur radio satellites and use the NORAD number rather than a satellite name or designation when searching for TLEs. Program STSORBIT PLUS Satellite Orbit Simulation Page 60 Preparing File STSPLUS.FRQ for Amateur Radio Use ------------------------------------------------ File STSPLUS.FRQ contains the parameters required for STSPLUS to operate in the Doppler Shift Mode. Each entry (line) in the file includes the satellite NORAD Number, UPLINK and DOWNLINK center freqencies, and the transponder mode, specified in in that order, separated by commas and without any leading or trailing spaces. The following format is used for each entry: 00000,100,100,1 (Default values if sat not included) 18129,145.8900,29.3900,1 (Parameters for NORAD #18129) --+-- ----+--- ---+--- + | | | | | | | +-- Transponder Mode: 1 = NORMAL | | | -1 = INVERTED | | | | | +------- DownLink Center Frequency (MHz) | | | +--------------- UpLink Center Frequency (MHz) | +----------------------- Satellite NORAD Number The first sample line shows the "00000" entry which determines the default values if the satellite is NOT included in file STSPLUS.FRQ. This should be the FIRST LINE in file STSPLUS.FRQ. The second line gives real parameters for a specific satellite; the frequencies shown select the Mode A voice passband for Radio Sputnik 10 (RS-10, piggybacked on COSMOS 1861, NORAD #18129). Preset frequencies may range from 1.0000 MHz to 99000.0000 MHz. Neither the uplink nor downlink frequency should exceed approximately 99000.0000 MHz to avoid an overflow condition on the display. Although the center frequencies are shown above in MHz, any desired units may be used since STSPLUS simply calculates a ratio and displays the results with four digits to the right of the decimal point. File STSPLUS.FRQ may be created or edited with any ASCII editor; word processor users, use the "non-document" mode. Note that only minimum error checking is performed and the user must observe the required format exactly for each line in the file. Up to ten entries may be included for a given satellite (using the same NORAD Number) in order of preference. If more than one entry is present for the current satellite, the user is presented with a list and asked to make a choice. Ken Ernandes, N2WWD, in conjunction with his tests of STSPLUS' Doppler Shift Mode, has prepared a preliminary STSPLUS.FRQ file with the current (as of March, 1994) center frequencies of fourteen amateur radio satellites. Note that several satellites have more than one entry, corresponding to different modes of operation: 00000,100,100,1 (Default values) 14129,435.1025,145.9025,-1 (AO-10) 16609,145.5500,145.5500,1 (MIR) 18129,145.8850,29.3800,1 (RS-10) 18129,21.1800,145.8800,1 18129,21.1800,29.3800,1 19216,435.4950,145.9000,-1 (AO-13) Program STSORBIT PLUS Satellite Orbit Simulation Page 61 19216,144.4500,435.9650,-1 19216,1269.4750,435.8600,-1 19216,435.6190,2400.7290,-1 20437,145.9750,435.0700,1 (UO-14) 20439,145.9000,437.02625,1 (PACSAT) 20441,1265.0000,437.0751,1 (WO-18) 20441,1265.0000,437.1258,1 20442,145.8400,437.15355,1 (LO-19) 20480,145.9550,435.8500,-1 (FO-20) 21087,435.0160,145.9870,1 (AO-21) 21087,435.0620,145.8920,-1 21087,435.0830,145.9060,-1 21089,21.2400,29.4400,1 (RS-12/13) 21089,21.2400,145.9400,1 21089,145.4400,29.4400,1 21575,145.9000,435.1200,1 (UO-22) 22077,145.9000,435.1670,1 (KO-23) 22077,145.9000,435.1200,1 22825,145.8500,436.8000,1 (AO-27) NOTE: The center frequencies listed above are preliminary, based upon available information. For example, the uplink frequencies for the first entry for RS-10 and the entry for FO-20 have been adjusted up by 5KHz to compensate for an apparent transponder bias. These data will be coordinated by Ken Ernandes, N2WWD. Ken may be contacted through my RPV Astronomy BBS at (310) 541-7299 or on CompuServe at 70511,3107. Users who have carefully calibrated their receivers and transmitters and who have updated information are encouraged to contact Ken. SAREX, the Shuttle Amateur Radio EXperiment, is due to fly next on the STS-59 Mission in early April, 1994. The following uplink and downlink frequencies have been assigned for that flight: UPLINK DOWNLINK NOTES ------------------------------------------- VOICE: 144.91 MHz 145.55 MHz EXCEPT EUROPE 144.93 144.95 144.97 144.99 144.70 MHz 144.55 MHz EUROPE ONLY 144.75 144.80 PACKET: 144.49 MHz 145.55 MHz WORLDWIDE NASA adds the following note with respect to the voice uplink: "The astronauts will not favor any one of the above frequencies. Therefore, the ability to talk with an astronaut depends on selecting one of the above frequencies chosen by the astronaut." (Information courtesy NASA Spacelink BBS as of March, 1994) Thus, for a station in North America, the user may add the following entries to file STSPLUS.FRQ: Program STSORBIT PLUS Satellite Orbit Simulation Page 62 00059,144.91,145.55,1 00059,144.93,145.55,1 00059,144.95,145.55,1 00059,144.97,145.55,1 00059,144.99,145.55,1 00059,144.49,145.55,1 where "00059" must be replaced by the actual NORAD number once that number is assigned. Temporary NORAD number "00059" will be used until the permanent NORAD number is assigned. Because different sources of 2-line elements (TLEs) may use different names for these satellites, always use the NORAD Number when searching a file for the TLEs. For AO-13, for example, press F2, select the desired TLE filename, then enter "#19216" (without the quotation marks but WITH the pound sign) as the satellite name. This method will ALWAYS find the data if they are present in the file. Once the data are found, STSPLUS displays them as usual. If there is only one entry in file STSPLUS.FRQ for the satellite, STSPLUS will immediately draw the map after ENTER is pressed to approve the satellite and its data. However, if more than one entry for the satellite is present, AND STSPLUS is currently in the Doppler Shift Mode, STSPLUS will display a list of the available preset frequencies and request the user to select one: Preset Frequency Selections for 19216 # UpLink DnLink Mode --------------------------------- 1 435.4950 145.9000 -1 2 144.4500 435.9650 -1 3 1269.4750 435.8600 -1 4 435.6190 2400.7290 -1 Enter Desired Preset Frequency Selection Number [1]: Enter the desired preset frequency selection number followed by ENTER. If you wish selection #1, you may simply press ENTER. Entering a number less than 1 or greater than the highest selection number will also pick selection #1. Note that when STSPLUS is NOT in the Doppler Shift Mode, no list of preset frequency selections is displayed and STSPLUS automatically picks selection #1 (to avoid bothering folks who are not interested in the Doppler Shift Mode).