Abstract: A modulator includes input paths for audio information from an electronic audio channel; output paths for transmitting said audio information over a frequency-modulated radio frequency signal to a FM broadcast receiver; and one or more programs for measuring or estimating the spectrum environment of the frequency-modulated RF signal bearing the audio information through sampling and analysis to select an optimum radio signal level and signal transmission mode for transmission to the FM receiver in a near interference free manner.

Abstract: A spread spectrum communications system includes an encoder for differentially encoding a spread spectrum spreading code sequence in accordance with an input data signal. Each chip of the spreading code sequence is inverted, or not inverted, relative to the polarity of a corresponding chip of the spreading code sequence a fixed time delay previously, depending on whether the input data is a logic one or zero, respectively. At the receiver, the data is recovered in a differential data decoder wherein the presently received chip of the spread spectrum signal and a corresponding previously received chip of spread spectrum signal, received a fixed time delay previously, are compared one chip at a time. Since it is the spreading code sequence that is differentially encoded and differentially decoded, there is no need for a synchronized code sequence generator at the receiver, and data synchronization is achieved after one cycle time of the received spread spectrum spreading code sequence has elapsed.

Abstract: A multiple phase PSK demodulator for use in a spread spectrum communication system includes a plurality of baseband frequency converters coupled to a corresponding plurality of differential decoders in order to directly recover the encoded PSK data. The logic outputs of the plurality of differential data decoders are coupled to a majority vote logic circuit for determining the correct logic level output signal of the plurality of differential data decoders. In another embodiment, a three phase resistive network is used to convert the two phase quadrature output of two baseband frequency converters to plural phase outputs coupled to the inputs of a corresponding plurality of differential data decoders.