UHF Satcom Adjacent Channel Emissions and Modem Implemention Loss: Predictions/Measurements for the Linear Phase SBPSK Modulation Waveform Family

Abstract

Transmission over US-owned UHF SATCOM channels necessitates the use of bandwidth efficient modulation techniques that require the selection of data rates and modulation formats to optimize the transmitted energy contained in the allocated channel and minimize the energy spillage to the adjacent channels. The constant envelope shaped binary phase shift keying (SBPSK) with 50% shaping has been specifically called out in ML-STD-188-181A to be the recommended waveform of choice for both the 5 kHz and 25 kHz channels. The relative amount of power spilled out in the adjacent channels for 50% shaping is quantified into allowable adjacent channel emissions (ACE) and is tabulated in the MIL-STD. Extensive analytical results for ACE prediction for the upper and lower five adjacent channels as a function of shape factor is presented in this paper. The shape factor is varied from 50 to 100 % in 5 % increments. ACE experimental measurements using a 100 Watt UHF SATCOM transmitter is also presented. Performance in terms of BER implementation loss as a function of shape factor is also presented in this paper. Computer simulation results show good agreements with measured experimental results