A superconductive resonant cavity is energized with radio-frequency energy. The cavity includes a tuning stub having a piece of semiconductor material mounted on the end thereof. An incoming communication signal modulates a light source optically coupled to the semiconductor by a fiber optic bundle. This varies the dielectric constant of the semiconductor which, in turn, varies the resonant frequency of the cavity. An angle modulation demodulator senses the frequency of the radio-frequency oscillations in the cavity and produces a replica of the communication signal with improved signal-to-noise ratio.
A distortion free fiber optic system having a single-mode optical fiber utilized in combination with a semiconductor material mounted in optical alignment therewith. Although it is preferable for the semiconductor material to be adjacent the input end of the fiber, it may, in the alternative, be placed adjacent the output end of the fiber. For appropriate distortion free propagation of a beam of electromagnetic radiation through the optical fiber, the semiconductor material must be receptive to the wavelength of the electromagnetic beam. This can be accomplished by either matching the semiconductor material to the wavelength of the beam or tuning the source of the electromagnetic beam to the excitonic-polariton resonance of the semiconductor crystal.
A local oscillator for use in an optoelectronic distance measurement system for generating a narrow-band HF signal for direct signal mixing with a reception signal generated by an avalanche photodiode (2) from a light signal impinging on the latter, with the depletion layer capacitance (C.sub.APD) of the avalanche photodiode (2), which varies due to different influences and specimen scatter, is incorporated, as an element which (co-)determines the oscillator frequency, in a controllable HF resonant circuit whose HF resonant frequency is determined, for example, by the adjustable divider ratio of a PLL-circuit (1) which is acted upon by a phase-locked reference oscillator (6) and which controls the capacitance (C) of a capacitance diode (3) connected in parallel with the depletion layer capacitance.
The present invention relates to a novel use of cryoelectronic equipment to implement an extremely sensitive and stable receiver front end for UHF, microwave, and millimeter wave applications. The invention is particularly applicable to base station receivers in mobile radio systems, where the range and capacity of the systems are typically limited by the base station receiver sensitivity.
The present invention relates to a novel use of cryoelectronic equipment to implement an extremely sensitive and stable receiver front end for UHF, microwave, and millimeter wave applications. The invention is particularly applicable to base station receivers in mobile radio systems, where the range and capacity of the systems are typically limited by the base station receiver sensitivity.
The present invention relates to a novel use of cryoelectronic equipment to implement an extremely sensitive and stable receiver front end for UHF, microwave, and millimeter wave applications. The invention is particularly applicable to base station receivers in mobile radio systems, where the range and capacity of the systems are typically limited by the base station receiver sensitivity.
