International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A simple, low cost radio frequency (RF) power and spectrally efficient integrated transceiver/modem architecture employing Feher’s patented Quadrature Phase Shift Keying (FQPSK) is described. The FQPSK signals presented in this paper are obtained by using additional post low-pass filters in the FQPSK architecture. This implementation significantly improves the spectral efficiency of the worldwide commercially standardized Gaussian Minimum Shift Keying (GMSK) systems. The Bit Error Rate (BER) performance of FQPSK in additive white Gaussian noise (AWGN) channel has been investigated by means of computer simulation and hardware prototype measurements. The results of the hardware and software simulations are compared to GMSK and QPSK/OQPSK performance. These results show that the filtered FQPSK modulated signal passing through a non-linear amplifier (NLA) can achieve a spectral efficiency improvement of about 60% over NLA filtered OQPSK and an integrated spectral efficiency improvement of 50% over GMSK and a better BER performance. In particular, 100 kb/s to 34 Mb/s hardware experimental results over 2.4 GHz NLA (saturated) 1 Watt system confirmed that FQPSK hardware systems attain a BER=f(Eb/N0) performance within 1 dB to 2 dB of predicted theoretical results.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Blind adaptive equalization with application for Non-Linearly Amplified (NLA) quadrature amplitude modulation (QAM) systems in multipath selective fading channels is presented. With an offset sampling strategy in the receiver, the proposed blind equalization using Constant Modulus Algorithm (CMA) exhibits a fast convergent speed for a family of quadrature modulated systems in NLA and multipath fading channels. Feher’s patented Quadrature Phase Shift Keying (FQPSK) and Feher’s Quadrature Amplitude Modulation (FQAM) which correspond respectively to 4-state and 16-state QAM are used due to their higher Radio Frequency (RF) power and spectral efficiency in NLA channel. It has been shown that blind adaptive equalization can significantly open the eye signals in multipath frequency selective fading channels.