Application of the threshold-extension technique in a DBS environment is described. For DBS signals comprising analog-video and OQPSK modulated data, computer simulations are used to determine optimum deviations of the RF carrier by video and OQPSK signals. With these deviations, parameters of a second-order phase-locked loop (PLL) threshold extension demodulator are optimized to yield a static-th...Show More
The use of encryption technology in the delivery of premium television is described. Signal security concepts such as scrambling, encryption, key-management etc. as applied in the ORION and SIGMA systems are discussed. In order to asess the effects of transmission link and system induced impairments, an analytical procedure is developed for the encryption method used in ORION/SIGMA. System perform...Show More
A more accurate calculation of the signal-to-noise ratio (SNR) at the output of an ideal FM detector (calculated by [2]) is proposed. The derivation takes into account the nonstationarity of the output noise power and shows that the actual SNR is much lower than that found in [2], for high index modulation.Show More
Suboptimum SSB-PM envelope and phase detectors are considered and their performances above threshold are evaluated and compared. The results show a slight superiority of the phase SSB-PM over the envelope SSB-PM demodulator. Both detectors show poor performance for high index modulation. A lower bound on the MMSE of an optimum SSB-PM demodulator is computed and it is shown to be slightly higher th...Show More