Abstract: A one-way and two-way multichannel radio frequency transmission system and method employing a sectorized broadcasting technique is described. The system and method reduces the effective bandwidth of the broadcast signal by multiplexing available channels of signals into a set of formatted independent digital bitstreams—where each of the bitstreams includes all or a portion of the available channels provided by the system program provider. The independent bitstreams are transmitted to transmitting towers using point-to-point transmission methods. The transmitting towers phase modulate and amplify the bitstreams to generate a set of independent modulated signals. Each transmitter tower includes an antenna for broadcasting the modulated signals to a sectorized service area each sector in the service area receiving a different one of the set of independent modulated signals. The antenna includes a set of individual antenna panels each panel for broadcasting one of the set of modulated signals.

Abstract: An integrated OMT/filter assembly is small, low cost and not easily susceptible to mechanical or environmental damage. The integrated OMT/filter assembly has a body formed at least in part of conductive material, the body including a first port for receiving a transmit signal, a second port for feeding the transmit signal to an antenna and for receiving a receive signal, and a third port for receiving the receive signal. A first waveguide segment joins the first and second ports, and a second waveguide segment joins second and third ports, the first and second waveguide segments having a portion in common. A filter element is disposed within at least one of the first and second waveguide segments.

Abstract: A method and system of frequency multiplying a signal having amplitude modulation using a frequency multiplier operated at a bias voltage that is less than its saturation mode voltage is described. Prior to amplification, the amplitude modulated signal is pre-distorted to compensate for distortion caused by the frequency multiplier. A first pre-distortion phase converts the amplitude modulated signal into a corresponding square root signal to compensate for a first distortion type. A second pre-distortion phase pre-distorts the square root signal to compensate for the distortion caused by biasing the frequency multiplier at a voltage less than the saturation voltage of the multiplier. As a result, a signal that is amplitude modulated can be multiplied by a frequency multiplier.

Abstract: A one-way and two-way multichannel radio frequency transmission system and method employing a sectorized broadcasting technique is described. The system and method reduces the effective bandwidth of the broadcast signal by multiplexing available channels of signals into a set of formatted independent digital bitstreams--where each of the bitstreams includes all or a portion of the available channels provided by the system program provider. The independent bitstreams are transmitted to transmitting towers using point-to-point transmission methods. The transmitting towers phase modulate and amplify the bitstreams to generate a set of independent modulated signals. Each transmitter tower includes an antenna for broadcasting the modulated signals to a sectorized service area--each sector in the service area receiving a different one of the set of independent modulated signals. The antenna includes a set of individual antenna panels--each panel for broadcasting one of the set of modulated signals.

Abstract: A thermoelectric cooler control circuit for a laser diode that has its terature regulated by a thermoelectric cooler and its temperature sensed by a laser diode temperature sensor. The purpose of the control circuit is to regulate the thermoelectric cooler to maintain the laser diode at a constant temperature. The output of the laser diode temperature sensor is amplified and compared to a reference voltage in an integrator. The output of the integrator controls a pulse width modulator that controls a switching transistor that varies the pulse duration of power applied to a filter network. The power output of the filter network is applied to a mode controller that is controlled by the output of the integrator so that the mode controller switches the direction that power is applied to the thermoelectric cooler to maintain the temperature of the laser diode at a constant level.

Abstract: An adaptive gain integrator circuit is provided having a first integrator for producing an output which is proportional to the ambient light noise level and the amplitude of the laser illumination signals applied thereto. A second feedback circuit having a noise-only integrator is provided to maintain the noise level applied to the first integrator substantially constant despite wide variations in the amplitudes of ambient light detected by the system, thereby to reduce the false alarm rate and increase the sensitivity of the system.

Abstract: A laser diode power supply that uses a proportional controller that drives series pass transistor to regulate laser diode current and the intensity of the laser diode output. The purpose of the controller is to maintain constant laser output power when its unregulated output power would otherwise gradually decrease with age. The laser diode includes a detector that samples light emitted from the laser diode. The output of the detector is amplified and compared to a reference voltage in an integrator. The output of the integrator controls a series pass transistor that varies to power to the laser diode to provide a constant laser diode power output. The controller also includes power limiting and transient voltage protection circuits.