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Re: 10GHz LNBs etc.



>to lock the DRO with a PLL, but obviously in the consumer DSS product, the
>free running stability is enough.

Indeed it is. That's because the DSS links are high speed QPSK at
about 20 megasymbols/sec. The carrier tracking loops in the receiver
can easily be made wide enough to track out the phase noise in the LNB
along with any residual doppler shift from an imperfect geostationary
orbit.

Digital links on poorer (lower C/No) channels have to run at lower
data rates where LO phase noise can become significant. That's been an
design issue for several of Qualcomm's products, where selection of an
LO with sufficiently low phase noise was necessary to take care of it.

Phil

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