Abstract: A fiberoptic probe for in situ sensing of liquid level, concentration and/or phase change contains the optical and electrical components as well as a reference fluid so that the components are at the temperature of the fluid to be monitored. A reference fiber is located in the reference fluid which is sealed in the probe so that volatile reference fluids can be used.

Abstract: A frequency-agile synchronous demodulator for demodulating a carrier signal. The carrier signal is decomposed into in-phase and quadrature-phase components. Using the in-phase and quadrature-phase components, a first error signal is produced representing the phase difference between the carrier signal and a local oscillator signal. A reference signal, related to the frequency of the carrier signal by a factor N, is also input to the frequency-agile synchronous demodulator. The local oscillator signal is scaled by the factor N, and compared to the reference frequency signal in a phase detector. The phase detector produces a second error signal representing the phase difference between the reference signal and the local oscillator signal. The first error signal is integrated and summed with the second error signal. The resultant sum signal is integrated and input to the local oscillator for controlling the frequency and phase thereof.

Abstract: A PSK demodulator demodulate a PSK signal into a digital data, which PSK signal is an encoded signal comprising a carrier phase shifted by a digital signal data.

Abstract: An FM signal demodulation circuit comprises a plurality of inverters and a capacitor. Each of the inverters is constituted by an integrated injection logic (I.sup.2 L) including a transistor and an injector current source.