Steve, your setting of "minimum elevation" will be the reason of your observation. The default setting of "minimum elevation" in WinAOS is 0 degrees. You should leave that setting or specify only a few degrees if there are obstacles around. As you wrote your setting is 15 degrees. With that setting the program does not only skip passes with a lower max. elevation but shows only the part of a pass the sat is above 15 degrees. That makes a difference of 4-5 minutes less transponder time at the beginning AND at the end of a pass because the elevation of a satellite changes much slowlier at low elevations than at higher ones. Many audible passes will not be displayed at all.
The purpose of WinAOS is to give you a quick overview over the audible passes of the selected satellites and for this purpose it completely sufficient and very useful (for me since more than 25 years). WinAOS uses a simpler orbit model than SatPC32 does (also SatPC32ISS, Wisat32 and WinListen) which uses the very exact SGP4/SDP4 model. Since WinAOS calculates in intervals of 1 minute the max. elevation may be wrong (too low, never too high) by some degrees - with high elevation the angle can change by 15 or more degrees within 1 minute. But that is not important The rising and setting times are exact within one minute.
For exact predictions you can use WinListen.
73s, Erich, DK1TB
Am 24.11.2014 05:21, schrieb Steve May:
I appreciate the suggestions. After a long day at work I have sat down this evening to look at the system, but I am still stumped.
I am using a Windows 8.1 system, and the clock appears to be synchronized correctly. I am letting Windows set it automatically, and when I look at my cell phone the two display the same time and the minutes change simultaneously.
The Keps seem to be updated correctly, and it shows that they are looking at the file that was updated earlier today. I looked in the directory and the updated nasa.all file is there.
The time seems to be incorrect for all of the satellites I am trying to predict. Since I am only concerned with AO-7, FO-29, AO-73, and SO-50 they are the only ones I a running a prediction for, and since I am pretty new a this I am trying to use a 15-degree minimum elevation.
I am generating a WinAos list, and it seems to be pretty much across the board hat the predictions in the WinAos software are about 5-6 minutes later than the predictions from the AMSAT website. Some of the predictions show a 1-degree difference in max elevation as well, although it isn't on every pass. These inconsistencies are probably based on rounding.
It is showing this difference in time on every satellite in the predictions as well.
I have checked and double-checked the Observer location on both predictions and I am using the correct location, EM78re. I have tried it on both predictions to enter the 6-digit grid square location as well as putting in the GPS coordinates manually and it doesn't seem to change anything.
I am stumped by this. I assume it has to be something in my SatPC32 setup, and I will try it at work tomorrow on a different machine to see if the errors are the same.
Any other suggestions?
Steve, W5IEM
On Sun Nov 23 2014 at 12:45:34 PM Erich Eichmann [email protected] wrote:
Steve, I compared the results of the pass prediction from the AMSAT website for the next 10 passes of FO-29 with the results of WinListen (that comes with SatPC32) for my location (8.9 degrees east, 51.94 north). The results are exactly the same (WinListen rounds the AOS/LOS times to the closest full minute, however). It requires to enter and save your QTH locator or longitude/latitude. I used the latest file nasa.all as Keps file.
in most cases of different results between the AMSAT pass precition and SatPC32 wrong longitude/latitude values in menu "Setup", "Observer" or "Setup" of WinListen or different Keplerian data were the reason.
What is your 6-digit QTH locator (or longitude west and latitude north)? What is the entry in SatPC32, menu "Observer" and in WinListen, menu "Setup"? What Keps file do you use? Download the Keps file you use from SatPC32 menu "Satellites", "Update Keps". When the download is successful click "Quit" and then "OK". The path to the Keps files folder can be seen in the foot line of menu "Satellites", the file date in the bottom line of the SatPC32 main window and in the left list of the menu you can choose the file. WinListen will use the same same path (foot line in menu "Listen").
73, Erich, DK1TB
Am 23.11.2014 17:04, schrieb Steve May:
I have noticed that when I update the Keplerian Data for my location on SatPC32 and generate a list of passes they all seem to be about 5 minutes different than the predictions from the AMSAT website. This is for the earliest pass, and I am using the exact GPS coordinates for my location.
So which do I rely on? Which predictions should I consider the "gold standard" for passes?
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Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb