Repeater

• US 5,852,629 A
• Filed: 06/22/1994
• Issued: 12/22/1998
• Est. Priority Date: 12/10/1993
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Iwamatsu, Takanori
• Primary Examiner(s): VO, DON NGUYEN
• Application Number:
  US08/263,686
• Time in Patent Office: 1,644 Days
• Field of Search: 375/211, 375/344, 455/22, 455/24, 455/20, 455/21, 455/23, 455/7, 455/11.1
• US Class Current: 375/211
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

A repeater wherein quadrature detection is performed using signal form a local oscillator nonsynchronized to a received carrier, and a baseband signal is reproduced, with the frequency and phase difference between the received carrier and the local oscillator being compensated for by means of a feedback loop consisting of a phase rotator, a controller, a loop filer, and a digital VCO. The reproduced baseband signal is quadratue-modulated with the signal from the local oscillator. The local oscillator necessary for the operation of the repeater is shared between the demodulator and the modulator; reductions in the size and cost of the repeater can be achieved.

Claims

1. A repeater in which a quadrature-modulated received signal is demodulated for the reproduction of a baseband signal, and the reproduced baseband signal is then quadrature-modulated for retransmission, comprising:

a local oscillator for outputting a local oscillation signal of a fixed frequency roughly equal to a carrier frequency of a received signal that is modulated with a baseband signal;

a quadrature detector for performing quadrature detection by applying the local oscillation signal to the received signal to reproduce said baseband signal;

an error-component eliminator for eliminating error components which are related to the difference between the carrier frequency and the local oscillation signal frequency and which are contained in an output of the quadrature detector, prior to the reproduction of the baseband signal; and

a quadrature modulator for quadrature-modulating the reproduced baseband signal for retransmission by applying the local oscillation signal to the reproduced baseband signal, wherein

the received signal includes a primary-polarization received signal carried on a primary polarized wave and a cross-polarization received signal carried on a cross-polarized wave normal to the primary polarized wave,

the quadrature detector includes a first quadrature detection circuit for performing quadrature detection by applying the local oscillation signal to the primary-polarization received signal, and a second quadrature detection circuit for performing quadrature detection by applying the local oscillation signal to the cross-polarization received signal;

the error-component eliminator includes a first error-component elimination circuit for reproducing the primary-polarization baseband signal by eliminating the error components contained in the output of the first quadrature detection circuit, and a second error-component elimination circuit for reproducing the cross-polarization baseband signal by eliminating the error components contained in the output of the second quadrature detection circuit, and

the quadrature modulator includes a first quadrature modulation circuit for quadrature-modulating the reproduced primary-polarization baseband signal by applying the local oscillation signal to the reproduced primary-polarization baseband signal, and a second quadrature modulation circuit for quadrature-modulating the reproduced cross-polarization baseband signal by applying the local oscillation signal to the reproduced cross-polarization baseband signal.

2. A repeater in which a quadrature-modulated received signal is demodulated for the reproduction of a baseband signal, and the reproduced baseband signal is then quadrature-modulated for retransmission, comprising:

a local oscillator for outputting a local oscillation signal of a fixed frequency roughly equal to a carrier frequency of a received signal that is modulated with a baseband signal;

a quadrature detector for performing quadrature detection by applying the local oscillation signal to the received signal to reproduce said baseband signal;

an error-component eliminator for eliminating error components which are related to the difference between the carrier frequency and the local oscillation signal frequency and which are contained in an output of the quadrature detector, prior to the reproduction of the baseband signal; and

a quadrature modulator for quadrature-modulating the reproduced baseband signal for retransmission by applying the local oscillation signal to the reproduced baseband signal,

a PLL circuit for outputting a locally generated synchronized signal that is synchronized to the local oscillation signal, wherein

the received signal includes a primary-polarization received signal carried on a primary polarized wave and a cross-polarization received signal carried on a cross-polarized wave normal to the primary polarized wave,

the quadrature detector includes a first quadrature detection circuit for performing quadrature detection by applying the local oscillation signal to the primary-polarization received signal, and a second quadrature detection circuit for performing quadrature detection by applying the locally generated synchronized signal to the cross-polarization received signal;

the error-component eliminator includes a first error-component elimination circuit for reproducing the primary-polarization baseband signal by eliminating the error components contained in the output of the first quadrature detection circuit, and a second error-component elimination circuit for reproducing the cross-polarization baseband signal by eliminating the error components contained in the output of the second quadrature detection circuit, and

the quadrature modulator includes a first quadrature modulation circuit for quadrature-modulating the reproduced primary-polarization baseband signal by applying the local oscillation signal to the reproduced primary-polarization baseband signal, and a second quadrature modulation circuit for quadrature-modulating the reproduced cross-polarization baseband signal by applying the locally generated synchronized signal to the reproduced cross-polarization baseband signal.