Intermodulation Considerations for the GAPFILLER Satellite.
NAVAL RESEARCH LAB WASHINGTON D C
Pagination or Media Count:
The Navy intends to lease the UHF portion of the MARISAT Satellite system. This portion of the MARISAT, referred to by the Navy as GAPFILLER, consists of a wideband 500 kHz and two narrowband 25 kHz translating, hardlimiting, repeating channels. The current intent of the Navy is to utilize the wideband channel as 19 adjacent 25 kHz accesses. Because of nonlinear elements in the transmit chain of the satellites, multiple signal use creates intermodulation products in the transmitted spectrum. Some of these signals, although attenuated by filtering and antennae isolation, fall into the receive channel band. Because of the low power level of the desired signals to be received, these intermodulation products can cause serious degradation to satellite performance if not adequately suppressed. In addition to careful engineering and spacecraft design, frequency choice plays a significant role in determining the potential impact of intermodulation products on satellite operation. Since the frequency plan and operating access frequencies for GAPFILLER have been determined, it is the intent of this report to determine the order in which accesses should be eliminated from the satellite to decrease degradation of operation due to intermodulation product effects.
- Unmanned Spacecraft
- Radio Communications