Abstract: A receiver apparatus adapted to be synchronized with a link transmitter to identify and isolate a transmitted, modulated carrier signal from other RF transmissions by obtaining A/D samples at each integer ? zero crossing of a transmitted signal and at the half Hertz cycles (?/2 and 3 ?/2) of the modulated carrier signal. The integer ? A/D samples are at the carrier signal zero crossings and thus contain only the other RF and noise in the receiving antenna. The half Hertz cycle A/D samples contain both the carrier signal and the other RF being received at that instant.

Abstract: A carrier state modulator system is described in which a stream of digital data bits is encoded by modulating the amplitude or phase of a carrier wave. A transmitter modulates the amplitude of a selected number cycles of the carrier in accordance with the state of each digital data bit. A receiver decodes the carrier state modulated signal by determining a phase score for the specified number of cycles of the modulated signal, the phase score based on a number of samples of the amplitude on a positive side of each cycle of the modulated signal that is above a selected amplitude and a second number of samples of an amplitude on a negative side of each cycle of the modulated signal that is below the selected amplitude. The value of the encoded digital data bit of the modulated signal is determined from the phase score.

Abstract: A transmitter includes an oscillator that generates a clock signal and a mapping unit that maps received data-bits to symbols and designates each of the symbols as three or more signal coding levels, where each of the signal coding levels are represented by a plurality of digital codes. The three or more signal coding levels representing each symbol are DC balanced and include a plurality of peak amplitudes. The transmitter further includes a digital to analog convertor that converts the plurality of digital codes to a corresponding plurality of analog amplitude levels at a rate determined by the clock signal, whereby the analog amplitude levels generate a signal coding level. A filter then smoothes the plurality of analog amplitude levels and generates a modulated carrier wave that is coded by the symbols.

Abstract: A carrier state modulator system is described in which a stream of digital data bits is encoded by modulating the amplitude or phase of a carrier wave. A transmitter modulates the amplitude of a selected number cycles of the carrier in accordance with the state of each digital data bit. A receiver decodes the carrier state modulated signal by determining a phase score for the specified number of cycles of the modulated signal, the phase score based on a number of samples of the amplitude on a positive side of each cycle of the modulated signal that is above a selected amplitude and a second number of samples of an amplitude on a negative side of each cycle of the modulated signal that is below the selected amplitude. The value of the encoded digital data bit of the modulated signal is determined from the phase score.