Pulse or digital communications – Transceivers – Loopback mode
Reexamination Certificate
2008-01-15
2008-01-15
Tse, Young T. (Department: 2611)
Pulse or digital communications
Transceivers
Loopback mode
C375S281000, C375S308000, C455S024000, C455S069000, C455S083000
Reexamination Certificate
active
07319716
ABSTRACT:
In a transceiver comprising a time-division-duplex (TDD) of transmit and receive functions, the characteristics of unwanted image signal energy being transmitted from the transceiver are determined, and thereafter feedback is provided to the transmitter to reduce this unwanted image signal energy. The image signal energy is measured by the receiver component of the transceiver and fed back to the transmitter component of the transceiver. The transmitter component uses the fed back information to adjust the gain and or phase relationship between the quadrature signals that are subsequently quadrature-phase modulated and transmitted. A variety of techniques can be employed to allow the image signal energy to be measured directly by the receiver component. The phase modulation signals at the transmitter can be interchanged, so that the unwanted image signal energy is transmitted in the sideband of the intended signal. Alternatively, the phase modulation signals at the receiver can be interchanged, so that the receiver's operating frequency is shifted from the frequency of the transmitter's intended signal sideband to the frequency of the transmitter's unwanted image signal sideband.
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Patent Abstract of Japan, Publication No. 10242765A, Date of Publication Nov. 9, 1998.
NXP B.V.
Tse Young T.
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