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and an ephemeris uncertainty as defined in Table 6-9. This value applies at the
carrier tracking threshold. The carrier tracking threshold for DG1 signals is a
minimum Prec of -201.4 dBW or the minimum Prec for BER, whichever is greater.
The carrier tracking threshold for DG2 signals is a minimum Prec of -195.3 dBW
or the minimum Prec for BER, whichever is greater.
6.3.3.4 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 with an ephemeris uncertainty as defined in Table 6-9, 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 SSA 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
SSA 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.
6.3.3.5 Additional Service Restrictions
a. Sun Interference. The TDRSS SSA return service performance will not be
guaranteed when the center of the sun is within 4 degrees of the TDRS SSA
receiving antenna boresight; however, this sun interference checking is a
customer MOC responsibility. Additionally, the TDRSS SSA 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 SSA return service can support the
customer platform with assigned frequencies anywhere within the 2200 to 2300
MHz band with either RHC or LHC polarization. The following restrictions
apply:
1. The BER relationships of Table 6-9 are satisfied for center frequencies
from 2205 to 2295 MHz (refer to Appendix D for power level restrictions
into the 2290-2300 MHz band and NASA/GSFC Recommended Filtering).
For customer center frequencies below 2205 MHz or center frequencies
above 2295 MHz, acceptable data service may be achieved when the
customer’s spectrum does not spill over the edges of the 2200 to 2300
MHz band.
2. The customer platform spectrum should be constrained so that the first
null of the spectrum falls within the 2200 to 2300 MHz band.
3. In addition, the customer platform should consider employing selectable
polarization capability.
Revision 10 6-35 450-SNUG