Abstract: An optical signal generator is configured with an associated control system and driver configured to reduce speckle. Speckle reduction occurs by pulsing the drive signal between a first current level and a second current level. These pulses force the optical signal generator to introduce oscillations into the optical signal. The coherence of the emitted light is reduced during the period of oscillations in the optical signal, which reduces speckle. In one embodiment, the pulsing of the drive signal brings the drive signal down to a level near or below threshold, which in turn intermittently turns off the optical signal output. Returning the optical signal to a desired optical output intensity introduces the speckle reducing oscillation. The pulse frequency, and duty cycle is controlled by a duty cycle control signal to modulate overall optical power and adjust amount of despeckle.

Abstract: An optical signal generator is configured with an associated control system and driver configured to reduce speckle. Speckle reduction occurs by pulsing the drive signal between a first current level and a second current level. These pulses force the optical signal generator to introduce oscillations into the optical signal. The coherence of the emitted light is reduced during the period of oscillations in the optical signal, which reduces speckle. In one embodiment, the pulsing of the drive signal brings the drive signal down to a level near or below threshold, which in turn intermittently turns off the optical signal output. Returning the optical signal to a desired optical output intensity introduces the speckle reducing oscillation. The pulse frequency, and duty cycle is controlled by a duty cycle control signal to modulate overall optical power and adjust amount of despeckle.

Abstract: A visual indicator notifies an occupant of an unsafe wiring condition in an electrical outlet or switch. The visual indicator and the electrical conductors inside the outlet being thermally connected, but electrically separated. When a threshold temperature is reached which is outside the normal operating temperature of an electrical outlet, the visual indicator will change state to notify occupants of a wiring problem.

Abstract: A motion detector combines an FCC approved homodyne pulsed range-gated radar (“RGR”) detector (10) and a PIR detector (158). Narrow microwave pulses are transmitted at a predetermined pulse repetition frequency (“PRF”) and the pulses are reflected by a target. The RGR detector senses the presence of moving human sized objects within predetermined ranges. Moving objects beyond the ranges are not sensed. The RGR detector employs a pulsed microwave oscillator (12) that is triggered by a system clock (14) and immediately retriggered after a 3 to 100 nanosecond delay (20). The duration of each pulse is 3 to 20 nanoseconds with a half-sine envelope shape. The RGR employs a homodyne detector (36) and shares an antenna (38) with the transmitter. The receiver range is determined by the delay imposed between the transmitted pulses, the first being a transmitted pulse and the second being a local oscillator pulse. Each received 5.8 GHz pulse is mixed down to a baseband by the homodyne detector.

Abstract: A magnetically actuated switch system (10) has reduced sensitivity to false alarms and reduced power consumption and resistance to physical and magnetic tampering. The system includes a signal processing circuit controlled by a microprocessor (16) that selectively enables magnetic sensors (12, 38), and compares the corresponding sensor outputs (76) to automatically calibrated level and predetermined timing characteristics.

Abstract: An input signal is sampled by alternately coupling the input signal and a reference level to a sample storage element, whereby the magnitude of the signal stored by the storage element immediately following application of the input signal to the storage element is a function of the input signal magnitude and the magnitude of the signal stored by the storage element immediately preceding coupling of the input signal to the storage element is a function of the reference level.

Abstract: An input signal is sampled by alternately coupling the input signal and a reference level to a sample storage element, whereby the magnitude of the signal stored by the storage element immediately following application of the input signal to the storage element is a function of the input signal magnitude and the magnitude of the signal stored by the storage element immediately preceding coupling of the input signal to the storage element is a function of the reference level.

Abstract: An avalanche photodiode non-linearity correction circuit cancels a portion of a non-linear recovery error response by the APD to an input signal by using the fact that the non-linear recovery error is only mildly dependent upon the APD gain. The gain of the APD is varied from data acquisition cycle to data acquisition cycle, with the acquired data being stored. The stored data from consecutive data acquisition cycles are combined in a summation circuit to effectively cancel a significant portion of the non-linear recovery error response.

Abstract: An automatic trigger mask for an optical time domain reflectometer inhibits high optical level pulses in a received optical signal from saturating an optical detector in a receiver. A portion of the received optical signal is compared with a threshold signal derived from the output of the receiver. If the portion of the received optical signal exceeds the threshold signal, then a control signal is generated to open an optical switch in the optical path to the receiver so that the high optical level pulses are inhibited from reaching the optical detector.