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Text File | 1987-08-30 | 30KB | 598 lines

O R B S Orbital Prediction Program for Earth Orbiting Satellites Version 2.1 USER REFERENCE 8/30/87 Ron Dunbar, W0PN ========= O R B S ========= INTRODUCTION: ORBS is a menu-driven system which produces printed listings showing an earth-orbiting satellite's azimuth, elevation, range as well as other approprate data at specified intervals of time as seen from an observer's location. Perhaps the easiest way to give you an idea of ORB's features is to start with the opening menu: = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = O R B S = = = = ORBITAL PREDICTION PROGRAM WITH TIME WINDOWS = = 8/22/1987 = = Ron Dunbar W0PN = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 1. Generate orbital predictions. 2. Update Elements. 3. Modify beacon frequency file. 4. Modify station call/location file. 5. Exit to operating system. Your choice.. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Let's investigate the menu items one at a time... 1. GENERATE ORBITAL PREDICTIONS: If you choose this function, the next screen you'll see will look something like this: = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = This program prints tracking data for earth-orbiting satellites SATELLITE SELECTION MENU 1. oscar-9 ID = 12888 Set 1066 8/17/87 2. oscar-10 ID = 14129 Set 305 8/7/87 3. oscar-11 ID = 14781 Set 245 8/6/87 4. oscar-12 ID = 16909 Set 55 7/28/87 5. rs-5 ID = 12999 Set 426 8/13/87 6. rs-7 ID = 13001 Set 337 8/17/87 7. rs-10/11 ID = 18129 Set 60 8/17/87 8. meteor 2-14 ID = 16735 Set 126 5/31/87 9. meteor 2-15 ID = 17290 Set 87 8/16/87 10. meteor 3-1 ID = 16191 Set 689 8/16/87 11. noaa-9 ID = 15427 Set 186 8/7/87 12. noaa-10 ID = 16969 Set 70 8/14/87 13. mir ID = 16609 Set 782 8/17/87 14. salyut-7 ID = 13138 Set 732 8/17/87 15. ajisai ID = 16908 Set 50 8/8/87 16. Cosmos 1870 ID = 18225 Set 38 8/11/87 SELECT SATELLITE? = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Now choose the satellite you're interested in, answer a few questions, and the printed listing is produced in record speed, thanks to Turbo BASIC's nimble compiled code and Tom Clark's QUICKSTEP algorithm trickery (that's the infamous W3IWI, you know) which speeds up the calculations when the satellite is below the horizon. As you answer the questions mentioned above, you'll note that another unique feature has been added; TIME WINDOWS. You have the option of ignoring all satellite passes outside a selected timeframe.. after all, there's little value in spending time calculating and producing a listing covering times when you can't be there to see/hear/work that satellite, is there? TIME WINDOWS will allow you to span 2400 UTC with your window time; you can specify a window such as 2200 to 0400, and it will be handled properly. The TIME WINDOW feature is particularly useful for listing the 'good' visual passes of MIR and COSMOS 1870, for instance, because you can only see them during the period between local civil twilight and the time when they are enveloped in the earth's shadow. Now let's see what a typical listing looks like. We'll use Oscar-9: = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = *** O R B S *** OSCAR-9 Orbital Predictions Page # 1 for W0PN at Lat: 46.871 Lon: 92.103 Element set 1066 is 7.5 days old Listing covers the period 237.0000 to 237.5000 or 12.00 hrs. This listing run at 00:40:06 on 08-25-1987. PARAMETER REFERENCE STARTING --------- --------- -------- Catalog number 12888 Epoch 87229.50723967 87237.00000000 Inclination 97.6439 [ No change ] R. A. A. N. 248.5757 256.2849 Eccentricity 0.00029260 [ No change ] Arg. Perigee 33.8666 7.4516 Mean Anomaly 326.2793 195.4792 Mean Motion 15.29943109 15.29988380 Drag Correction 3.021E-005 [ No change ] Orbit number 32611 32726 S.M.A.,(km) 6854.0761 6853.9409 Perigee Ht, km 473.9106 473.7754 Apogee Ht, km 477.9216 477.7863 Freq (MHz) 145.825 (F1) 435.025 (F2) ************************************************************* Printing only the window between 0130:00 and 0500:00 UTC. ************************************************************* U T C AZ EL 145.825 435.025 RANGE HEIGHT LAT LONG PHASE F2 TRACK hhmm:ss deg deg DPLR Hz DPLR Hz km km deg deg <256> 435.025 - - - Orbit # 32728 - - - Day # 87237 - - - Tuesday, 8/25/87 - - - 0226:00 263 1 +1320 +3938 2417 474 40.6 119.5 24 435.021 0228:00 285 2 +206 +613 2366 474 48.1 122.0 29 435.024 0230:00 306 -1 -972 -2901 2606 474 55.6 125.2 35 435.028 End of OSCAR-9 listing. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = As you can see by the information between the lines of asterisks, we specified a 'time window' of 0130 to 0500 UTC, which is late enough for most of us here in the Midwest, and prior to that time, we're probably eating supper. You can further see (in the 5th printed line) that we specified a 12 hour period, and only one pass was visible (and print- ed) which occurred in that 12 hour period AND was within our specified time window. You will also note from the ELevation column that it was a marginal pass, just barely peeking up over the horizon to the west of this QTH. Note that two 'beacon' frequencies were present for Oscar-9 in the FREQS.ORB file.. 145.825 and 435.025 MHz. The doppler associated with each frequency is listed in the 4th and 5th columns of the printout... the column heading shows the frequency the doppler is computed for. The RANGE, HEIGHT, LAT and LONG all refer to the satellite. The LAT and LONG are the point on the earth over which the satellite is currently positioned (the Sub-Satellite Point, or SSP). The RANGE is the distance from the observer in meters, and the HEIGHT is the satellite's altitude above the earth in meters. LAT and LONG are in degrees, of course. Note the rightmost column labeled "F2 TRACK". The numbers in this column represent the frequency you must transmit on to 'hit' the F2 TRACK frequency (435.025) as seen at the spacecraft.. this listed frequency takes the doppler into consideration and is a handy feature when you need to uplink at a specific frequency. One of the last questions you are asked before the program goes off to compute all this stuff is whether you would like to manually enter an alternate frequency for F2. This lets you temporarily override the frequencies contained in the FREQS.ORB default file. (More on that later). Ok, now you've run your listing, and you've just downloaded the AMSAT Orbital Data Bulletin and captured this week's latest Kepler elements into your STUFF.LOG file. Use your favorite word processor in the NON- DOCUMENT MODE (please) to edit STUFF.LOG and get rid of everything except the elements. You can leave in all the carefully constructed headers, asterisks, etc., but clean out all the stuff not relating to the Bulletins. Be sure to check the bulletin for typos.. sometimes the ':' following the keywords gets lost, or 'e' (as in "1.687e-04") turns up missing. The program will catch the first error, but not the second one. It can show up as subsurface apogee and perigee heights in the parameter listing on the first page.. that's why that listing is there! If you come up with anything that looks weird, check and correct the ELEMENTS file, then redo the update operation. All bulletins should be combined into one file which MUST be named ELEMENTS (no .EXTension, please). Now move that file into the same directory that ORBS resides in (I call it \ORBS, for want of a better name.. I have trouble remembering obscure names, birthdays, etc.). If you spell ELEMENTS wrong or forget to move it into the \ORBS direc- tory, you'll get a RUNTIME ERROR 53: which says you spelled ELEMENTS wrong or forgot to move it to the \ORBS directory.. don't DO that! 2. UPDATE ELEMENTS: Now, we're ready to choose item (2) on the ORBS menu. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ORBITAL ELEMENT UPDATE PROGRAM = = = = 8/23/1987 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Scanning input file... please wait. Total number of satellites read from the ELEMENTS file = 16 Total number of satellites written to the KEPLER.ORB file = 16 The frequency data in FREQS.ORB will be inserted into the records contained in KEPLER.ORB. FREQS.ORB contains 5 records for input. 5 insertions completed. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Now, wasn't that a lot easier than typing in 14 numbers for 16 dif- ferent satellites? You didn't have to do anything but sit there and wonder what the computer was doing (especially when it was messing around with your hard disk). You've just updated all the Keplerian elements for all the satellites contained in the bulletin in about one minute or less! What actually happened was that (1) the program ORBUPDAT.TBC was called by the menu program. (2) The file ELEMENTS was read in, (3) the beacon frequency data from the file FREQS.ORB was merged with the ELEMENTS data, and (4) the combined data was written to the KEPLER.ORB file which is used by the tracking program ORBP.TBC. KEPLER.ORB is the source of the data that is displayed as the list of satellites from which you choose when you do menu item (1), "Generate orbital predictions". Let's suppose that a new satellite has been placed in orbit, and it contains a beacon or two which you want to monitor. You're ready for the next menu choice... 3. MODIFY BEACON FREQUENCY FILE: When you make this choice from the menu, you'll see this.... = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Modify FREQS.ORB Entries = = = = 8/23/1987 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Existing entries will be presented for possible modification, followed by blank entry(s) to allow you to add to the list of satellite beacon frequencies; the frequency specified can be any you wish to track; it doesn't have to be strictly a beacon. Make certain you enter the satellite's CATALOG number accurately.. the record is keyed on it. Satellite name: Oscar-9 Catalog number: 12888 Frequency 1: 145.825 Frequency 2: 435.025 Accept, Delete, Modify this entry (A/d/m): = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note the prompt line.. the 'A' is in UPPER CASE. This is the convention I use to indicate the DEFAULT you will get if you just hit the ENTER key. You may also type an 'a' if you wish to follow directions. If you Accept this entry, the next satellite contained in the FREQS.ORB file will be presented in order, and so on until the entries are exhausted. If you choose to DELETE the entry, it goes away.. simple. If you choose to MODIFY it, BE VERY CAREFUL that you get the "Catalog number" right! You can misspell the name, but the catalog number is the key to matching this data up with it's counterpart contained in the ELEMENTS file. If you choose MODIFY, the cursor moves to the field following "Satellite name:" and waits for your action. If you merely hit ENTER, the data in that field remains unchanged and the cursor moves on to the next field. If you modify a field, any data remaining in the field beyond the cursor is erased before the cursor advances to the next field. When you ENTER following the last field (enter '0' if you don't want one of the beacon frequencies anymore), you are asked "Is data correct (Y/n):". If you made an error, you can redo it by answering 'n', otherwise, a 'y' or an ENTER will accept the modifications. When you have responded to the last entry and hit the ENTER key to accept the data, the following appears: = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Modify FREQS.ORB Entries = = = = 8/23/1987 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Existing entries will be presented for possible modification, followed by blank entry(s) to allow you to add to the list of satellite beacon frequencies; the frequency specified can be any you wish to track. It does not have to be strictly a beacon. Make certain you enter the satellite's CATALOG number accurately.. the record is keyed on it. Satellite name: Catalog number: Frequency 1: Frequency 2: Make an entry (y/N): = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = You have noticed, of course, that all the fields are empty, and the prompt is asking whether you wish to make a new entry. Remember to get that "Catalog number" right! I suppose that you'd like to get your call letters and location stuck in here somewhere.. that brings us to the next main menu function..(4): = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Modify ORB.CFG Entries = = = = 8/24/1987 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = The ORBS.CFG file contains 'station specific' data used by the prediction program. The existing entry will be displayed for possible modification. Latitude is entered as decimal degrees (nn.nnn); South latitudes are preceeded by a '-' (-nn.nnn). Longitude is entered as decimal degrees West longitude. Station Altitude is entered in meters, not feet. Minimum elevation is that elevation (in degrees) above which you wish the printout to commence (usually 0 or -1). Station call: W0PN Station latitude: 46.871 Station W. longitude: 92.103 Station altitude: 435 Min sat elevation (deg): -1 Accept or Modify this entry (A/m): Most of the fields are pretty self-explanatory. The Station latitude and longitude must be in decimal degrees, not degrees, minutes, etc. The longitude is specified as WEST longitude.. none of that '-179.999' stuff allowed. The altitude is in METERS, not feet or furlongs. If you don't want to forever run listings with my call and coordinates on them, I suggest you choose to MODIFY this entry. When you have completed your task (operates the same as the previous function), you will receive this screen: = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Modify ORB.CFG Entries = = = = 8/24/1987 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = The ORBS.CFG file contains 'station specific' data used by the prediction program. The existing entry will be displayed for possible modification. Latitude is entered as decimal degrees (nn.nnn); South latitudes are preceeded by a '-' (-nn.nnn). Longitude is entered as decimal degrees West longitude. Station Altitude is entered in meters, not feet. Minimum elevation is that elevation (in degrees) above which you wish the printout to commence (usually 0 or -1). Station call: W3IWII Station latitude: 66.871 Station W. longitude: 74.103 Station altitude: 250 Min sat elevation (deg): -1 Is data correct (Y/n): = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Again, you have a chance to correct any typos. The only remaining main menu function is (5) Exit to operating system. That one ALWAYS works exactly as it's supposed to, even after extensive and rigorous testing conditions (read: exiting to fix another bug!). AFTERTHOUGHTS: The only feature remaining to be incorporated into ORBS is the 'mutual view' function. This allows you to have up to 5 stations as observers per listing.. (multiple observers). One of the stations (probably YOU) is the MASTER, and whenever the satellite is in view of any of the other stations at the same time it is in your view, those stations call letters will be printed along with azimuth and elevation data pertaining to them. Version 3.1 (if I ever find time to do it) will include that feature. Please forward your comments, suggestions and abuse to me via AMSAT Telemail (RDUNBAR), or you can try to reach me where I now live (but I don't expect to be here long.. hi!): Ron Dunbar, W0PN (Res) 218-728-6544 920 W. Tischer Road (Bus) 218-720-2093 Duluth, MN 55803 ..and I thank you for your support! Supplemental: The ARChived file of which this document file is a part, contains the following files: ELEMENTS ORBP .TBC FREQS .ORB ORBS .CFG KEPLER .ORB ORBS .DOC MODCFG .TBC ORBS .EXE MODFREQ .TBC ORBUPDAT.TBC ELEMENTS: Contains a recent version of the AMSAT Orbital Data Bulletin which is prepared weekly for AMSAT NA by Vern Riportella, WA2LQQ or Ralph Wallio, W0RPK. This file is normally captured directly from a bul- letin board system (BBS). ORBS allows you to input this unedited data file directly, thereby avoiding the formidable task of entering the data manually. You can also download current Bulletins by calling W0RPK's BBS at 515-961-3325. This service is also being provided by others; just ask around, or leave a query on Ralph's BBS when you call in. A sample of the first few lines of a typical Orbital Data Bulletin: ******************************************************************* * A M S A T O R B I T A L D A T A B U L L E T I N * * ORBS227O 15AUG87 * * Prepared for AMSAT-NA by W0RPK * ******************************************************************* Orbital Elements for OSCARs SAT. UO-9 AO-10 UO-11 FO-12 RS-5 RS-7 RS-10/11 SET# 62 305 245 55 425 335 52 NEW? Y Y Y N N Y Y Satellite: oscar-9 Catalog number: 12888 Epoch time: 87218.25756376 Element set: 1062 Inclination: 97.6454 deg RA of node: 237.0035 deg Eccentricity: 0.0003676 Arg of perigee: 58.3920 deg Mean anomaly: 301.7665 deg Mean motion: 15.29888737 rev/day Decay rate: 2.007e-05 rev/day^2 Epoch rev: 32439 Satellite: oscar-10 Catalog number: 14129 .....etc.................FREQS.ORB: Contains user defined beacon frequencies for selected satellites. When you choose "Update Elements." from the ORBS menu, the ORBUPDAT routine merges the data from the FREQS.ORB file with the data from the ELEMENTS file to produce the file KEPLER.ORB, which is used directly by the ORBS tracking program, ORBP.TBC. As supplied, FREQS.ORB contains the following data: "Oscar-9", 12888,145.825,435.025 "Oscar-10",14129,145.810,145.987 "Oscar-11",14781,145.826,435.026 "Oscar-12",16909,435.795,145.850 "rs-10/11",12999,145.857,145.907 Each line (or record) is terminated in a <CR/LF> to indicate the end of the record. You need not worry about constructing this file yourself, because ORBS provides you with a menu selection which does the hard work for you. ORBS.CFG: Contains station specific data. As supplied, ORB.CFG contains the following: "W0PN",46.871,92.103,435,-1 This entry is followed by a <CR/LF> to indicate the end of the record. LATE NOTES: ---------- Julian search time: When you're running a listing, you will notice a highlighted 6 digit number spinning in the upper right corner of your screen.. the 6 digit number is followed by a single '0' or '1' which appears to change randomly. The label to the left of the number says "Julian search time:". This is the instantaneous day of the year and fractional part of the day that is being used in the determination of the satellite's position. The 0/1 following indicates whether the satellite is below or above the observer's horizon. It's just a 'warm blanket' to let you know the computer is actually doing something between printouts. Sidereal Time table: I neglected to mention that the sidereal time tables have been eliminated because that figure is now calculated internally by the program included in DATESUBS.INC, a portion of ORBP.