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SN User's Guide - ESC Home - NASA

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Revision 10 C-4 450-<strong>SN</strong>UG<br />

Parameter Initiated or<br />

Scheduled<br />

by<br />

Doppler<br />

Compensation<br />

Predicted Local<br />

Oscillator (LO)<br />

Frequency (fo ) (in<br />

SHO or<br />

reconfiguration<br />

OPM [Class 3])<br />

Forward Service<br />

Frequency Sweep<br />

Expanded<br />

Frequency<br />

Uncertainty<br />

Table C-1. Customer MOC Controllable Parameters Which Impact Acquisition<br />

Customer<br />

MOC<br />

Customer<br />

MOC<br />

Customer<br />

MOC<br />

Customer<br />

MOC<br />

Customer Services<br />

Affected<br />

Impact on T acq<br />

Impact on<br />

Acquisition<br />

Sequence<br />

Comments<br />

All forward services Decreased T acq None Recommended. Not required if<br />

customer platform has<br />

capability to resolve Doppler by<br />

onboard processing.<br />

All forward services or<br />

noncoherent return<br />

services<br />

Acquisition cannot be<br />

achieved unless the<br />

uncertainty of the<br />

predicted frequency<br />

and the unresolved<br />

Doppler are within the<br />

acquisition bandwidth<br />

of the receiver<br />

Subsequent steps<br />

cannot be achieved<br />

All forward services Increased T acq Sweep is scheduled<br />

and implemented<br />

Return service noncoherent<br />

operation:<br />

DG1 mode 2<br />

DG2 (noncoherent)<br />

Crucial in establishing forward<br />

service and noncoherent return<br />

service<br />

OPM allows fo reconfiguration if<br />

SHO fo is outside of both the<br />

acquisition bandwidth of the<br />

receiver and the forward<br />

frequency sweep range<br />

(forward services) or the<br />

expanded frequency<br />

uncertainty range (noncoherent)<br />

return service.<br />

Employed when the customer<br />

MOC cannot define fo<br />

accurately<br />

Independent of Doppler<br />

compensation<br />

Increased T acq None Employed when the customer<br />

MOC cannot define f o<br />

accurately

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