Telecommunications – Transmitter and receiver at same station
Reexamination Certificate
1999-03-03
2002-04-16
To, Doris H. (Department: 2682)
Telecommunications
Transmitter and receiver at same station
C455S084000, C455S307000
Reexamination Certificate
active
06374086
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radio transmitter/receiver, and more particularly to operating channel selection.
2. Description of the Related Art
A reduction in cost and an improvement in reliability are amongst the benefits that may be obtained when it is possible to achieve a reduction in the number of separate components of a radio transmitter/receiver. Improvements in the performance of the radio may also be obtained by means of the integration of components previously required to be provided separately. Also a minimum bandwidth for the IF filter, consistent with adequate reception of the wanted signal will enhance receiver performance considerably.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a improved means for frequency and channel selection for both receiver and transmitter in a radio transmitter/receiver while reducing the number of separate components required.
According to the present invention there is provided a radio transmitter/receiver, the receiver having a first, fixed frequency local oscillator the output from the fixed frequency local oscillator being multiplied in frequency by a frequency multiplier to provide an input to a first mixer for down-conversion of input RF signals to IF, the IF frequencies being selected by a voltage controlled band-pass filter for down-conversion to base-band signals in a second mixer by mixing with an output from a second, variable frequency local oscillator.
The above and other objects, features, and advantages of the present invention will become apparent from the following description with references to the accompanying drawings which illustrate examples of the present invention.
REFERENCES:
patent: 4513447 (1985-04-01), Carson
patent: 4965852 (1990-10-01), Sasaki
patent: 5335364 (1994-08-01), Heinonen
patent: 5550520 (1996-08-01), Kobayashi
patent: 5748046 (1998-05-01), Badger
patent: 5812612 (1998-09-01), Saito
patent: 5930686 (1999-07-01), Devllin et al.
patent: 5999824 (1999-12-01), Na
patent: 6169447 (2001-01-01), Tolson
NEC Corporation
Sughrue & Mion, PLLC
To Doris H.
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