Adaptive Equalization for SQPSK and SQPR Over Frequency Selective Microwave LOS Channels
This paper compares the effectiveness of linear and decision feedback equalizers in counteracting the effect of frequency-selective distortion in microwave relay links. A quadratic frequency-selective model of the channel is employed and particular attention is given to channels with a null in the passband. Both staggered QPSK and QPR modems are studied. Performance is studied for error probability and mean squared error. The general conclusion is reached that a decision feedback equalizer is required for robust performance.
We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and the propagation ::: dynamics of an ultrashort laser pulse in a Ti:Sapphire laser oscillator. This study confirms the dispersion ::: managed model of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating mode-locked ::: spectra with a smooth and well-behaved spectral phase. A very good agreement with experimental measurements ::: of pulse energy, spectrum, and temporal width of extracavity compressed pulses is found.