I found this paper: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CC4QFjAA&url=http%3A%2F%2Fmarine.rutgers.edu%2F~kerfoot%2Fpub%2Fslocum%2FRELEASE_6_32%2Fsrc%2Fdoco%2Fspecifications%2Firidium-phone%2FIR_Lband.doc.rtf&ei=U6NbUrCdCuakiQLXgoGwAw&usg=AFQjCNHpZ7_Jh9hNlGLTvRbkVi2o7ancYQ&sig2=bC2RkaZCSpODi-QVR7z2mA&bvm=bv.53899372,d.cGE
Which seems to state that the subscribers of Iridium communications (the handset) adjust for Doppler shift. Each satellite is spaced such that there is also a "guard band" so they don't interfere with each other. Bryce On Sun, Oct 13, 2013 at 6:55 PM, <[email protected]> wrote: > On 13 Oct 2013 at 18:30, Dave Marthouse wrote: > > > This isn't a question regarding amateur satellites but it is an > interesting > > theoretical one to pose here and the same laws of physics apply. I know > > that the higher the frequency that is transmitted from a satellite the > > larger the Doppler shift will be. The Iridium satellites transmit at > around > > 1.5gHZ. At that frequency I know the Doppler is large. How do they > manage > > to keep the portable handsets on the ground locked to the signal? Are > the > > handsets frequency agile to an extent? How do they achieve frequency > lock > > so that the digital signals are decoded? > > > > > > > > Dave Marthouse N2AAM > > [email protected] > > > Interesting question Dave > > I suspect as the XM/SIRIUS radio a data signal is sent back to the > receiver position to minimized the doppler effect and some sort of data > error correction also help to counteract the doppler effect. A similar > system is implemented into the wxtoimg NOAA weather satellite fax > decoding software. > > It is an educated guess who only need to be reeducated... Lets say my > Sirius receiver in a plain flat field suffer some signal breaks that > i can't explain. > > > > > Luc Leblanc VE2DWE > WAC BASIC CW PHONE SATELLITE > > > _______________________________________________ > 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
