Regenerative RF bi-directional amplifier system
First Claim
1. In an RF communication system using a plurality of cascaded amplifier stages for amplifying signals being transmitted and received along a plurality of lengths of transmission line, the improvement wherein successive signal amplification is realized with reduced intermodulation distortion, the improvement comprising the steps of:
- down-converting the transmitted RF signals to an intermediate frequency (IF) level by using a pilot signal in combination with a local oscillator signal,applying said down-converted IF signals, in combination with said pilot signal, to said transmission line lengths,at each of said amplifier stages, up-converting said IF signals to regenerate the original RF signals using said pilot signal,amplifying said IF signals to a desired level,amplifying said regenerated RF signals to a desired level and applying the signals to the lengths of transmission line at the output end of said amplifier stages, andapplying said amplified IF signals and said pilot signals to said output transmission line for regenerating said RF signals at the succeeding amplifier stage.
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Accused Products
Abstract
A regenerative RF bi-directional communications system is provided for establishing RF coverage within a RF block tunnel area. The system uses a plurality of cascaded amplifier stages for periodically regenerating signals which are transmitted and received along a series of radiating cable length which link base station transceivers to hand-held or like mobile communication units. An intermediate frequency distribution system is used so that the required level of amplification is achieved through the several cascaded amplifier stages at the level of low-power IF signals generated from the original RF signals in conjunction with the appropriate oscillator and pilot signals. The IF distribution system restricts the cascading effect occurring due to the plurality of cascaded amplifier stages on the relatively low-power IF signals, thereby producing a negligible amount of intermodulation.
207 Citations
14 Claims
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1. In an RF communication system using a plurality of cascaded amplifier stages for amplifying signals being transmitted and received along a plurality of lengths of transmission line, the improvement wherein successive signal amplification is realized with reduced intermodulation distortion, the improvement comprising the steps of:
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down-converting the transmitted RF signals to an intermediate frequency (IF) level by using a pilot signal in combination with a local oscillator signal, applying said down-converted IF signals, in combination with said pilot signal, to said transmission line lengths, at each of said amplifier stages, up-converting said IF signals to regenerate the original RF signals using said pilot signal, amplifying said IF signals to a desired level, amplifying said regenerated RF signals to a desired level and applying the signals to the lengths of transmission line at the output end of said amplifier stages, and applying said amplified IF signals and said pilot signals to said output transmission line for regenerating said RF signals at the succeeding amplifier stage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A two-way communication system for establishing RF signal coverage within a RF-blocked area such as a tunnel, subway or the like comprising:
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at least one base station for transmitting and receiving RF signals inside or outside said RF blocked area; at least one radio unit disposed within said RF blocked area; a plurality of lengths of radiating cable disposed within said RF blocked area and arranged to radiate signals from said base station (the "transmit" signals) being propagated therethrough so as to be received by a radio unit located about said cable, and to receive RF signals from such a radio unit (the "receive signals") and relay the signals to said base station; and a plurality of amplifier stages linking and radiating cable lengths, said amplifier stages adapted to amplify both said transmit and receive signals; said base station comprising means for down-converting the transmit RF signals to a band of intermediate frequency (IF) signals by using a pilot signal in conjunction with a local oscillator signal; means for applying said down-converted IF signals, in combination with said pilot signal, to said radiating cable lengths; each of said amplifier stages comprising means for up-converting said IF signals to regenerate the original RF signals using said pilot signal; means for amplifying said IF signals and said regenerated RF signals to the radiating cable length at the output end of the amplifier stage; and means for applying said amplified IF signals and said pilot signal to said radiating cable length, in order that said RF signals may be regenerated at each succeeding amplifier stage to provide IF signals and amplified regenerated RF signals, wherein successive signal amplification at each of said plurality of amplifier stages is realized with reduced intermodulation distortion. - View Dependent Claims (9, 10, 11, 12)
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13. In a distributed amplification system using a plurality of cascaded amplifier stages for amplifying RF signals transmitted therethrough, a method of reducing intermodulation distortion in the amplified RF signals while achieving the desired level of amplification, the method comprising the steps of:
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down-converting the transmitted RF signals to an intermediate frequency (IF) level by using a pilot signal in combination with a local oscillator signal to provide IF signals, amplifying said IF signals to a desired level, and up-converting said amplified signals, using said pilot signal, to regenerate the original RF signals at each amplifier stage where said RF signals are required, wherein the overall intermodulation generated by said distributed amplification system is substantially independent of the number of said plurality of cascaded amplifier stages. - View Dependent Claims (14)
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Specification