Abstract: An optical transmitter architecture has a return-to-zero (RZ) laser modulator coupled in cascade with a non-return-to-zero (NRZ) laser modulator. Modulator bias and electronic phase delay bias are controlled using dither-based feedback, so as to align the phase of the RZ clock signal with that of the NRZ data. A first method uses an RZ quadrature AM dither or an RZ “hillclimber” bias dither, to apply a relatively low frequency dither signal to a variable RF delay for the RZ clock signal applied to the RZ modulator or NRZ data signal applied to the NRZ modulator. A second method is an RZ quadrature AM dither or “hillclimber” bias dither scheme that applies equal amplitude and opposite phase dither signals to perform complementary modulation of both the RZ and NRZ MZ modulators simultaneously.

Abstract: An optical transmitter architecture has a return-to-zero (RZ) laser modulator coupled in cascade with a non-return-to-zero (NRZ) laser modulator. Modulator bias and electronic phase delay bias are controlled using dither-based feedback, so as to align the phase of the RZ clock signal with that of the NRZ data. A first method uses an RZ quadrature AM dither or an RZ “hillclimber” bias dither, to apply a relatively low frequency dither signal to a variable RF delay for the RZ clock signal applied to the RZ modulator or NRZ data signal applied to the NRZ modulator. A second method is an RZ quadrature AM dither or “hillclimber” bias dither scheme that applies equal amplitude and opposite phase dither signals to perform complementary modulation of both the RZ and NRZ MZ modulators simultaneously.

Abstract: An optical transmitter architecture has a return-to-zero (RZ) laser modulator coupled in cascade with a non-return-to-zero (NRZ) laser modulator. DC bias and modulation signal drive levels of the two modulators are controlled using dither-based feedback, so as to align the phase of the RZ signal with that of the NRZ data. A first method uses an RZ quadrature phase dither or an RZ hillclimber phase dither, to apply a relatively low frequency dither signal to a variable RF delay for the RZ clock signal applied to the RZ modulator. A second method is an RZ quadrature phase dither scheme that applies equal amplitude and opposite phase dither signals to perform complementary amplitude modulation of both the RZ and NRZ MZ modulators simultaneously.

Abstract: A system and method is disclosed for a radar receiver, such as a wideband crystal video early warning receiver, to automatically detect the noise level of the radar receiver with immunity to high pulse repetition frequencies and high duty cycle signals. The noise riding threshold circuit utilizes high frequency components of the noise and, to the attenuated extent present, high frequency components of the video signal to produce the noise riding threshold voltage. An amplifier gain control permits adjusting the noise-riding threshold to a fixed relative level. In a preferred embodiment, the noise riding threshold control of the present invention utilizes current feedback amplifiers for wide bandwidth, high gain video amplifiers.

Abstract: A multi-function radio frequency (RF) signal warning system detects different types of RF signals, such as radar signals, provided in various RF bands and provides an indication of the type of radar signal and the RF band. The system detects pulsed radar signals having different pulse repetition frequency (PRF) ranges as well as high duty cycle radar signals and continuous wave radar signals. The system includes a receiver processor that detects the radar signals, video amplifies the radar signals with baseline correction, and processes the radar signals to determine the type of radar signal, e.g., the RF band and PRF range. The receiver processor generates audio and visual control signals and transmits the control signals to one or more remote units. The remote units receive the audio control signals and generate an audible alarm.