Electro optical microwave communications system
First Claim
1. An electro optic microwave communications system comprising a receiver for receiving a high frequency microwave transmitted signal said receiver comprising:
- an antenna to receive the transmitted signal and to provide a received signal;
a photomixer connected to the antenna to provide an injection signal to mix with the received signal to down convert the received signal to an intermediate frequency (IF) signal;
a fixed laser that illuminates the photomixer at a first frequency;
a tunable laser that illuminates the photomixer at a second frequency; and
at least one fiberoptic cable that connects the fixed laser and the tunable laser to the photomixer;
wherein said photomixer mixes the fixed laser and the tunable laser to provide the injection signal at frequency equal to the difference of the first frequency and the second frequency.
1 Assignment
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Accused Products
Abstract
A wideband communications system uses a photomixer, a radio frequency (RF) mixer, and an antenna. The photomixer is comprised of high speed phototransistors that are illuminated by two laser beams. The laser beams are generated by two lasers, one tunable, and conveyed to the photomixer via fiber optic cables. The two beams are mixed by the photomixer to generate a radio heterodyne signal that is mixed with antenna signals to generate an intermediate frequency (IF) signal based on the differences of the generated heterodyne frequency and the antenna signals. Conventional fiber optic means may be used to convey the IF signals, along with the fiber optic cables to the photomixer, to and from a remote RF head located at some distance from the rest of the communications system to overcome losses in transmission lines.
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Citations
19 Claims
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1. An electro optic microwave communications system comprising a receiver for receiving a high frequency microwave transmitted signal said receiver comprising:
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an antenna to receive the transmitted signal and to provide a received signal; a photomixer connected to the antenna to provide an injection signal to mix with the received signal to down convert the received signal to an intermediate frequency (IF) signal; a fixed laser that illuminates the photomixer at a first frequency; a tunable laser that illuminates the photomixer at a second frequency; and at least one fiberoptic cable that connects the fixed laser and the tunable laser to the photomixer; wherein said photomixer mixes the fixed laser and the tunable laser to provide the injection signal at frequency equal to the difference of the first frequency and the second frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electro optic microwave communications system receiver for receiving a high frequency microwave transmitted signal said receiver comprising:
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an antenna to receive the transmitted signal and to provide a received signal; a mixer connected to the antenna to mix the received signal with an injection signal to down convert the received signal to an intermediate frequency (IF) signal; a photomixer connected to the mixer to provide the injection signal to mix with the received signal to down convert the received signal to the IF signal; a fixed laser that provides a fixed laser beam at a first frequency; a tunable laser that provides a tunable laser beam at a second frequency; an optical combiner connected to the fixed laser and the tunable laser to combine the fixed laser beam and the tunable laser beam; and a fiberoptic cable connected to the optical combiner to connect the fixed laser beam and the tunable laser beam to the photomixer; wherein said photomixer mixes the fixed laser beam and the tunable laser beam to provide the injection signal at frequency equal to the difference of the first frequency and the second frequency. - View Dependent Claims (12, 13, 14)
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15. An electro optic microwave communications receiver for receiving a high frequency microwave transmitted signal said receiver comprising:
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an antenna to receive the transmitted signal and to provide a received signal; a photomixer connected to the antenna to provide an injection signal to mix with the received signal to down convert the received signal to an intermediate frequency (IF) signal; a fixed laser that illuminates the photomixer at a first frequency; a tunable laser that illuminates the photomixer at a second frequency; an optical combiner connected to the fixed laser and the tunable laser to combine the fixed laser beam and the tunable laser beam; and a fiberoptic cable connected to the optical combiner to connect the fixed laser beam and the tunable laser beam to the photomixer; wherein said photomixer mixes the fixed laser beam and the tunable laser beam to provide the injection signal at a frequency equal to the difference of the first frequency and the second frequency and mixes the injection signal with the received signal to down convert to the IF signal. - View Dependent Claims (16, 17, 18, 19)
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Specification