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5.3.3.4 Reacquisition
While in the PN/carrier tracking state, a loss of lock condition induced by a cycle slip will
be automatically detected and a reacquisition will be automatically initiated. For a
customer platform that continues to transmit the minimum Prec for acquisition and
maintains an ephemeris uncertainty as defined in Table 5-8, the normal total channel
reacquisition time for either powered or non-powered flight dynamics will be less than or
equal to that for the initial total channel acquisition for non-powered flight dynamics, with
a probability of at least 0.99. If lock is not achieved within 10 seconds of loss of lock, an
acquisition failure notification will be sent to the MOC and the SN ground terminal will
reinitiate the initial service acquisition process. TDRSS MA return service does not
support acquisition of customers with powered flight dynamics. Upon receipt of the
loss-of-lock indications in the UPD, the customer MOC may request a TDRSS MA
return service reacquisition GCMR (refer to Section 10). It is recommended that the
customer MOC delay initiation of the GCMR for at least 35 seconds after initial receipt
of the loss-of-lock indications in the UPD.
5.3.3.5 Additional Service Restrictions
a. Sun Interference. The TDRSS MA return service performance will not be
guaranteed when the center of the sun is within 3 degrees (MAR) or 4 degrees
(SMAR) of the TDRS MA receiving antenna boresight; however, this sun
interference checking is a customer MOC responsibility. Additionally, the
TDRSS MA return service performance will not be guaranteed when the center
of the sun is within 1 degree of the boresight of the SN ground terminal
receiving antenna supporting the TDRS.
b. Frequency and Polarization. The TDRSS MA return service requires a
customer platform to transmit at 2287.5 MHz with LHC polarization (refer to
Appendix D for power level restrictions into the 2290-2300 MHz band and
NASA/GSFC Recommended Filtering).
5.3.4 Real-Time Configuration Changes
Changes to the operating conditions or configuration of a TDRSS MA return service
during a scheduled service support period are initiated by a GCMR from the customer
MOC. The requested changes will be implemented within 35 seconds of receipt of the
GCMR at the SN ground terminal. The MOC will be notified upon initiation of the
requested changes via GCM. Additional information concerning the SN ground terminal
response times for GCMRs is provided in Section 10. Table 5-10 lists the MA return
service real-time configuration changes and their effects on the return service.
Revision 10 5-31 450-SNUG