Binary and Quadrature Feher's Modulation (F-Modulation, or FMOD) Transmitter-Receiver
systems and circuits exhibit reduced envelope fluctuation and peak radiation, and
increased efficiency. A subclass of these systems has a constant envelope. They
advantageously provide lower power operation with improved performance including
robust BER performance, and compatibility with both linearly and nonlinearly amplified
narrow spectrum, and without disadvantages of conventional BPSK, DBPSK QPSK and
pi/4-QPSK. Feher's BPSK (FBPSK) is an improved efficiency transmitter which is
compatible with conventional BPSK receivers. FBPSK modems are based on using quadrature
structure where Q-channel data is inserted in quadrature with I-channel data for
certain applications. The Q-channel data may be "offset" from the I-channel data
by an amount selectable between zero and a specified time. Further improvement
in the spectrum is attained using correlation between I and Q channels. FBPSK modem
is shown to meet the IEEE 802.11 specified spectral direct sequence spread spectrum
mask (-;30 dB point) for wireless LAN, and leads to an output power gain of 6.5
dB over conventional BPSK modems. The cross-coupled quadrature FMOD structure is
also suitable for continuous mode and for burst operated TDMA, FDMA, CDMA, WCDMA
and CSMA Frequency Modulation Quadrature AM (QAM), QPSK and offset QPSK, as well
as pi/4-shifted QPSK modems/processors. Reduced modulation index Gaussian FSK (GFSK),
multilevel FM and cross-coupled Quadrature Amplitude Modulated (QAM) transmitters
and combinations of these modulations and corresponding coherent demodulators are
disclosed. Controlled rise and fall time descriptions of burst operated systems
are included.
