Hi David, G0MRF If you read the old issues of OSCAR-News from AMSAT-UK you will realize that a serious traking program like PLAN-10 written by James Miller G3RUH take into calculation all perturbations due to inclination and velocity of the satellite due to Earths rotational speed added / subtracted at either end of the pass and so doppler.
73" de i8CVS Domenico ----- Original Message ----- From: <[email protected]> To: <[email protected]> Sent: Sunday, June 10, 2012 1:20 AM Subject: [amsat-bb] Asymetric doppler curves? > Hi all. > > I'm doing a small demonstration for a physics class using Doppler > measurements on the HO-68 beacon. > > Hopefully we'll be able to calculate spacecraft velocity and from that > result, go on to calculate orbit altitude. However, in thinking about > this I realised that there is a potential source of error. We are not > stationary !! - OK, it's obvious really, but I've never seen this > mentioned in topics like Doppler correction programs and I've not seen > it visually in displayed Doppler curves. > > The issue is that while a spacecraft with zero eccentricity will have a > constant velocity, the speed relative to an observer on Earth at AOS > and LOS will be different for each half of the pass depending on the > observers latitude and the inclination of the satellite. > > The worse case would be something travelling East to West or West to > East as the velocity of the satellite would have the Earths rotational > speed added / subtracted at either end of the pass. > > Has anyone seen this effect? Perhaps on the ISS? I think it could be > as much as 7% which may be measurable. - But not on HO-68 which is > polar orbiting.... > > Just want to make the most of my 45 minutes. > > Thanks > > David G0MRF > > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
