Abstract: A diversity code transmission system and method are disclosed. The method including demodulating a first transmission signal using a first continuous phase demodulator resulting in a first output and passing the first output to a first de-interleaver resulting in a second output. The method further including demodulating a second transmission signal using a second continuous phase demodulator resulting in a third output and summing the second output and the third output resulting in a fourth output. The method also includes passing the fourth output to a second de-interleaver resulting in a fifth output and decoding the fifth output to provide a symbol output. The method also includes passing a decoded fifth output to a first interleaver and providing a first interleaver output to the second continuous phase demodulator. Last the method is repeated in an iterative process.

Abstract: A quadrature modulator compensation system for compensating the transmission of a source signal includes a transmitter which uses a transmitter input signal to generate a transmitter output. Calibration circuitry generates at least one of a phase error estimate of the transmitter, a gain error estimate of the transmitter, and a dc offset estimate. Predistortion circuitry receives the estimates and the source signal as inputs and provides the transmitter input signal as a function of the estimates.

Abstract: A diversity code transmission system is disclosed. The diversity code transmission system comprises an encoder encoding a set of bits. The system also comprises an interleaver receiving the encoded bits and providing an output. A coder or modulator for providing a first transmission signal is also used. The interleaver iteratively receives its own output to provide an iterated output to a coder or modulator to provide a diversity transmission signal. The receiving system supports iterative decoding and joint iterative demodulation and decoding.

Abstract: A squelch circuit for a radio receiver that detects the presence of speech by utilizing a filter bank for filtering an intermediate frequency or baseband signal from the radio receiver into band-pass signals, detecting the magnitude of the band-pass signals, and separating the signal magnitudes into a speech and noise detector. The speech detector determines if speech is present by determining if syllabic variations are present in the speech detector signals and selects a voice band average signal with a maximum difference in syllabic variations, and generates a speech detector decision when speech is present. The noise detector makes a noise detector decision when speech is present by obtaining a minimum noise detector signal and comparing the minimum noise detector signal to a threshold scaled voice band average signal associated with the maximum difference in syllabic variations.

Abstract: A tunable bandpass sigma-delta modulator analog-to-digital converter (A/D converter or ADC) utilized in conjunction with a digital signal processor (DSP) to eliminate the analog frequency synthesizer in a radio design is disclosed. The sigma-delta ADC greatly reduces the analog circuitry requirements and ensures that the circuitry is suitable for very large scale integration (VLSI). The all-digital DSP ensures the highest level of VLSI and provides for high performance frequency synthesis and translation completely in the digital domain.

Abstract: A communication system and a method for using an approximating frequency synthesizer with frequency correction by digital signal processing (DSP) means to provide a radio transmitter or receiver with rapid high resolution tuning capabilities. A user selects a frequency upon which he wishes to transmit or receive information. An approximating synthesizer is used to provide an RF injection frequency. A radio controller interprets the user selected frequency and determines the closet available approximating synthesizer frequency. The controller commands the approximating synthesizer to the determined available frequency and calculates the difference in the determined available frequency and the user selected frequency. The calculated difference or error is passed on to the DSP for correction during frequency mixing in a single or multiple step process.