IF and associated interface requirements applicable to Satellite Communications SATCOM Earth Terminals ET operating over military X-band and Ka-band Super High Frequency SHF channels. Military unique requirements for ET that may operate over commercial C-band, Ku-band, and Ka-band are included. Equipment developers may exceed the requirements herein to satisfy specific program requirements, provided that interoperability is maintained. Thus, incorporating additional standard and nonstandard capabilities and interfaces is not precluded. Existing SHF SATCOM terminals need not conform to this MIL-STD unless they undergo a modernization program.

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MIL-STD-188-164B

= pointing loss on the downlink at the given frequency dB = highest operational uplink frequency

= frequency of the downlink beacon

Should the uplink and downlink beams be significantly mis- aligned, or should they originate from different apertures, the above equation does not apply. In such a case, the individual beams will need to be compared to determine the uplink loss corresponding to a downlink loss due to mispointing. This shall be accomplished by converting the downlink pointing loss from

4.3.12 into a pointing error based on the receive (downlink) beam pattern. Assuming the transmit (uplink) and receive (downlink) beam pointing is coupled, this receive pointing error is then applied to the transmit (uplink) beam to determine the transmit pointing loss to be used in 4.2.4. For terminals with asymmetric beam shapes, these calculations shall be done at the worst case operational orientation of the beams.

For example, on WGS, the downlink Ka-band beacon is at 20.7 GHz while the uplink frequencies range between 30 and 31 GHz. Using these numbers along with a hypothetical circular center-fed terminal having a measured downlink loss of 1.0 dB gives an uplink loss of between 2.1 dB and 2.24 dB. In this case, the worst case uplink frequency loss of 2.24 dB would be utilized as the P2 loss component for calculating total EIRP stability (see

4.2.4).

Also, It can be seen from the equation that the closer the downlink frequency is to the uplink frequency, the closer the uplink and downlink losses will be. Therefore, simultaneous multiband terminals must always use the highest operational beacon signal for tracking purposes.

6.10 Changes from previous issue. Marginal notations are not used in this revision to identify changes with respect to the previous issue due to the extent of the changes.