[amsat-bb] Theoretical Question

[Dave Marthouse]

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
dmarthouse at gmail.com