Orbit visualization & antenna performance
Hello all,
In order to evaluate antenna effectiveness in the 70cm downlink band, I'm trying to visualize the orbits of the following satellites:
AO-27 SO-50 RS-44
I can find the perigee/apogee and output power on these, and, so far, I have:
AO-27 788x801 km 1W/0.5W/0.1W SO-50 603x713 km 0.25W RS-44 1175x1511 km 5W
On the FM birds: My observed data shows that SO-50 is difficult to hear while AO-27 is booming, so I hypothesize that AO-27 is transmitting with 0.5W or 1W.
RS-44's beacon seems to be fairly weak, while CW/SSB signals on the transponder are quite strong.
Does anyone know where I might find more details on RS-44's construction such as antennas and power output for the beacon?
Thanks,
--- Zach N0ZGO EM12jw
Not a direct answer to your question...but for 'orbit visualization'....
System's Tool Kit (STK) from AGI: https://www.agi.com/products/stk There is a free license for non commercial use (e.g. Ham Radio.....). With this you can quickly pull in TLEs for the spacecraft of interest and get very nice 3D and 2D displays to visualize orbits. You can also do things like run pass predictions ('accesses' in STK speak), get high time resolution az, el, range, and range rate (for Doppler and link analysis math) reports (in CSV format), and they have lots of tutorials for getting up and running. What you *can't* do with the free version is incorporate things like the Comm toolbox for direct antenna pattern visualization and link analysis within STK. From experience during my Master's work, the combination of 'free STK', 4NEC2 (and outputting theta/phi/Gain matrix), and Python can be a pretty powerful combo.....but lacks the 'visualize' part unless you want to code that up too....
The General Mission Analysis Tool (GMAT) is the free an open source competitor to STK from NASA: https://software.nasa.gov/software/GSC-17177-1. I have less experience (...i mean no experience...) with this package, so not sure how easy it is to use and whether or not is has antenna modelling features, but I know a lot of folks use it (including folks on this list) for orbit modelling.
Finally, speaking of Python, the skyfield package (https://rhodesmill.org/skyfield/) is a great way to 'get rid of STK' for your own projects. Skyfield provides a baked in SGP4 propagator to handle TLEs. That, plus modules such as pandas, matplotlib, openGL modules (for good graphics / 3D visualization), could make for a pretty nice package that gives you full control (and is free).....but this is a double edged sword as it would all need to be coded up, which can eat precious 'project time.' (I mention it because its somewhere way down on my project list...and there might already be something out there on this).
Hope this helps!
-Other Zach, KJ4QLP (the Zach with the Hat).
I wrote some code a while back in a google code project, that took TLEs and plotted the orbits in KML for visualization in Google Earth. It's all in Python, so really easy to work with from a developer standpoint and it also gives you access to some really nice geospatial libraries. I believe some others took the code and created githubs or other projects off of it, so it's still out there! I never created a homesite for it, because it literally took me one evening. I had plotted the entirety of the ARISSat-1 orbit, using the various TLEs published back then (and received legal permission to re-publish the TLEs). You could use the code to do what you want... Royalty free and 100% OSS:
https://www.gearthblog.com/blog/archives/2013/04/the_google_earth_satellite_...
And another hams github clone of the project...
https://github.com/u0m3/ge-satellite-tracker
If you'd like to build off of it at all or need any help, reach out to me anytime. If you PM me, I can send you my cell so you can coordinate directly, otherwise the code is reasonably straightforward.
Joseph Armbruster KJ4JIO
On Thu, Jul 23, 2020 at 5:45 PM Leffke, Zachary via AMSAT-BB amsat-bb@amsat.org wrote:
Not a direct answer to your question...but for 'orbit visualization'....
System's Tool Kit (STK) from AGI: https://www.agi.com/products/stk There is a free license for non commercial use (e.g. Ham Radio.....). With this you can quickly pull in TLEs for the spacecraft of interest and get very nice 3D and 2D displays to visualize orbits. You can also do things like run pass predictions ('accesses' in STK speak), get high time resolution az, el, range, and range rate (for Doppler and link analysis math) reports (in CSV format), and they have lots of tutorials for getting up and running. What you *can't* do with the free version is incorporate things like the Comm toolbox for direct antenna pattern visualization and link analysis within STK. From experience during my Master's work, the combination of 'free STK', 4NEC2 (and outputting theta/phi/Gain matrix), and Python can be a pretty powerful combo.....but lacks the 'visualize' part unless you want to code that up too....
The General Mission Analysis Tool (GMAT) is the free an open source competitor to STK from NASA: https://software.nasa.gov/software/GSC-17177-1. I have less experience (...i mean no experience...) with this package, so not sure how easy it is to use and whether or not is has antenna modelling features, but I know a lot of folks use it (including folks on this list) for orbit modelling.
Finally, speaking of Python, the skyfield package (https://rhodesmill.org/skyfield/) is a great way to 'get rid of STK' for your own projects. Skyfield provides a baked in SGP4 propagator to handle TLEs. That, plus modules such as pandas, matplotlib, openGL modules (for good graphics / 3D visualization), could make for a pretty nice package that gives you full control (and is free).....but this is a double edged sword as it would all need to be coded up, which can eat precious 'project time.' (I mention it because its somewhere way down on my project list...and there might already be something out there on this).
Hope this helps!
-Other Zach, KJ4QLP (the Zach with the Hat).
-- Research Associate Aerospace & Ocean Systems Lab Ted & Karyn Hume Center for National Security & Technology Virginia Polytechnic Institute & State University Work Phone: 540-231-4174 Cell Phone: 540-808-6305
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Zach Metzinger via AMSAT-BB Sent: Thursday, July 23, 2020 12:16 PM To: AMSAT BB amsat-bb@amsat.org Subject: [amsat-bb] Orbit visualization & antenna performance
Hello all,
In order to evaluate antenna effectiveness in the 70cm downlink band, I'm trying to visualize the orbits of the following satellites:
AO-27 SO-50 RS-44
I can find the perigee/apogee and output power on these, and, so far, I have:
AO-27 788x801 km 1W/0.5W/0.1W SO-50 603x713 km 0.25W RS-44 1175x1511 km 5W
On the FM birds: My observed data shows that SO-50 is difficult to hear while AO-27 is booming, so I hypothesize that AO-27 is transmitting with 0.5W or 1W.
RS-44's beacon seems to be fairly weak, while CW/SSB signals on the transponder are quite strong.
Does anyone know where I might find more details on RS-44's construction such as antennas and power output for the beacon?
Thanks,
--- Zach N0ZGO EM12jw
Sent via AMSAT-BB@amsat.org. 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: https://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. 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: https://www.amsat.org/mailman/listinfo/amsat-bb
participants (3)
-
Joseph Armbruster -
Leffke, Zachary -
Zach Metzinger