Abstract: LED junction temperature is determined in real time using the LED itself as the temperature sensor for directly measuring the LED junction temperature. In addition, temperature measurements from a silicon diode placed in proximity to the LED are also used to complement the temperature measurements from the LED itself. Arbitration is performed among temperature measurements from the LED and temperature measurements from the silicon diode to determine a temperature of the LED junction. The determined LED junction temperature may be used to make adjustments to the LED drive current. Temperature measurements from the LED are made in real time during actual operation by applying snooping currents to the LED during off-times of the PWM cycles of the LED, without interrupting normal operation of the LED.

Abstract: Voice activity is detected by comparing a signal with two thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adjusted based upon statistical information. In accordance with another aspect of the invention, the data can be weighted to provide an indication of the quasi-RMS energy of an input signal.

Abstract: Sub-band filtering, adaptive echo cancellation, and residual echo suppression are selectively and separately applied in hierarchical order under the control of a circuit that monitors four separate signals to determine n machine states. The number of machine states is further divided among m levels of noise in determining which, and how much of, sub-band filtering, adaptive echo cancellation, and residual echo suppression to use at any given time. A voice activity detector (VAD) is used to monitor each signal and provides statistical information in addition to whether or not a voice signal is detected. Sub-band filter, echo cancelling, and non-linear processing are not permitted to provide maximum reduction simultaneously. Even so, the invention provides at least 15 dB more echo suppression than systems without a sub-band filter bank series coupled with a non-linear processor in each channel.

Abstract: Voice activity is detected by comparing an analog signal with two voltage thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adjusted based upon statistical information. In accordance with another aspect of the invention, the data can be weighted to provide an indication of the quasi-RMS energy of an input signal. The input signal itself is not converted into digital form yet the data derived from the input signal has high resolution.

Abstract: Voice activity is detected by comparing a signal with two thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adjusted based upon statistical information. In accordance with another aspect of the invention, the data can be weighted to provide an indication of the quasi-RMS energy of an input signal. In accordance with another aspect of the invention, voice activity detectors, individually weighted, are provided at each input and each output of a telephone for reliably controlling echo cancelling circuitry within the telephone.

Abstract: Sub-band filtering, adaptive echo cancellation, and residual echo suppression are selectively and separately applied in hierarchical order under the control of a circuit that monitors four separate signals to determine n machine states. The number of machine states is further divided among m levels of noise in determining which, and how much of, sub-band filtering, adaptive echo cancellation, and residual echo suppression to use at any given time. A voice activity detector (VAD) is used to monitor each signal and provides statistical information in addition to whether or not a voice signal is detected. Sub-band filter, echo cancelling, and non-linear processing are not permitted to provide maximum reduction simultaneously. Even so, the invention provides at least 15 dB more echo suppression than systems without a sub-band filter bank series coupled with a non-linear processor in each channel.

Abstract: Voice activity is detected by comparing an analog signal with two voltage thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adjusted based upon statistical information. In accordance with another aspect of the invention, the data can be weighted to provide an indication of the quasi-RMS energy of an input signal. The input signal itself is not converted into digital form yet the data derived from the input signal has high resolution.

Abstract: Voice activity is detected by comparing a signal with two thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adjusted based upon statistical information. In accordance with another aspect of the invention, the data can be weighted to provide an indication of the quasi-RMS energy of an input signal.

Abstract: Voice activity is detected by comparing a signal with two thresholds and producing data representing the energy of the signal. The data, in binary form, is compared with thresholds to determine voice activity. In accordance with another aspect of the invention, the thresholds are adjusted based upon statistical information. In accordance with another aspect of the invention, the data can be weighted to provide an indication of the quasi-RMS energy of an input signal. In accordance with another aspect of the invention, voice activity detectors, individually weighted, are provided at each input and each output of a telephone for reliably controlling echo cancelling circuitry within the telephone.

Abstract: An imaging system (10) and method compensate for different amplitudes of pixel signals generated by photoactive devices in an optical sensor (32) whose responses to projected light are not uniform. The sensor is divided into regions (52) such that the response of the photoactive devices within a region are substantially equal. A processing circuit (34) compensates for different responses among different regions with a programmable gain amplifier (72) whose gain is dynamically adjusted when pixel signals generated in different regions are received.

Abstract: A short period of background noise is recorded during a call and then played back during non-speech intervals, thereby matching as nearly as possible the spectrum and amplitude of actual background noise during the call. Segments of the recording are played back in random order to mask repetition. Recording can take place more than once during a single call or take place in more than one session. In accordance with another aspect of the invention, a small amount of white noise is added to the recorded noise to improve the randomness of the sound.

Abstract: A circuit and method color balance pixel signals (VPIXEL) on-the-fly in an image capturing system (10). The pixel signals are amplified in a programmable gain amplifier (204) whose gain is set by the ratio of a programmable capacitor (320, 330) to a fixed capacitor (310, 311). Control data (CONTROL) sets the capacitance of the programmable capacitor by enabling switches (323-324, 333-334) that enable binary weighted capacitors (321-322, 331-332). The control data adjusts the gain of the programmable amplifier as each pixel signal is applied, so that the pixel signals of all primary colors are amplified in the same programmable gain amplifier.

Abstract: A circuit for detecting when a fault condition has occurred includes an input stage responsive to a logic signal supplied to an input of the circuit for providing an output logic signal at an output thereof. An output stage, including a pulldown circuit, responsive to the output logic signal of the input stage, for providing an output logic signal at an output of the circuit. A fault detection circuit coupled to the output of the input stage and to the output stage for forcing the output of the circuit to a predetermined logic state when the pulldown circuit of the output stage is defective.

Abstract: An integrated circuit chip which contains conventional clocked logic circuitry also contains a tester module for determining the minimum pulsewidth at which the clocked logic circuitry will operate. This tester module occupies a very small portion of the chip, yet it is able to generate several different variable width clock pulse sequences in which the pulsewidths range from being large enough for the clocked logic circuitry to properly operate to being too small for proper operation. By passing these sequences through the clocked logic circuitry, the minimum pulsewidth at which that circuitry will operate can be easily determined.