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: The present invention discloses a system and method of estimating phase error in a waveform sent from an analog transmitter. In a first technique, the ratio of the minimum to maximum envelope may be fit into a curve to determine the phase error of the waveform. In a second technique utilizing the maximum abscissa, the phase error estimate may be obtained utilizing an arctangent of an angle formed by a line from an origin through a point on the waveform at the index where the angle is equal to the phase error. A third technique for estimating phase error may involve determining an angle subtended by a line from an origin to an intersection and the closest axis, where the phase error estimate is twice the angle formed.

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 digital demodulator for demodulating baseband signals in a radio receiver. The demodulator includes a digital signal processing module for forming a mathematical series adapted for generating demodulation functions. The selection of coefficients for this series is controlled to provide specific demodulation functions as required for the demodulation of different kinds of signals such as amplitude modulated or angle modulated signals using one computational block or element. When demodulating amplitude modulated signals, the coefficients used in the mathematical series provide an approximation to the square root function. When demodulating phase or frequency modulated signals, the coefficients used provide an approximation to the arctangent function.

Abstract: FM signals are demodulated with lower distortion and expenditure of less computing time by digitizing the signals using an A/D converter of predetermined sample frequency and down-converting the signals to their base band quadrature components. The quadrature components are delayed by one sample period, and the complex cross-product of current quadrature components and the delayed quadrature components from the immediately preceding A/D sample period is taken. The arctangent of the resulting cross-product is taken by calculating the ratio of the imaginary and real components thereof to produce a value which is representative of the original modulating signal.

Abstract: The following specification describes a circuit breaker trip crossbar having diverging radial surfaces receiving a tapered rail therebetween. The rail extends from the bottom edge of the conventional breaker barrier wall recess and forms a small area pivot adjacent the crossbar axis to reduce the torque required to pivot the bar and to render the torque reproducible for calibration purposes.The radial surfaces are economically formed by flat mold surfaces in opposite mold halves to avoid mold flash in the pivot area while enabling one of the mold halves to conventionally form the latch plate securing hole in the crossbar.