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Browse Prior Art Database

Duplex Radio Modem with Single Oscillator

IP.com Disclosure Number: IPCOM000117911D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Camp Jr, WO: AUTHOR

Abstract

All full duplex radio links with simple FM modulation of the transmit oscillator, require a second oscillator for the receiver local oscillator. For very high frequencies, this extra oscillator is at the high frequency, and consequently is costly. This invention eliminates the need for the second high frequency oscillator.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 82% of the total text.

Duplex Radio Modem with Single Oscillator

      All full duplex radio links with simple FM modulation of the
transmit oscillator, require a second oscillator for the receiver
local oscillator.  For very high frequencies, this extra oscillator
is at the high frequency, and consequently is costly.  This invention
eliminates the need for the second high frequency oscillator.

      The solution to achieving a duplex radio architecture that uses
a single high frequency oscillator exploits the fact that there are
two ends of a radio link, and thus, two high frequency oscillators
available in the total system.  It makes use of image reject mixers
and one low frequency oscillator for each side of the system link.

      The duplex radio set consists of Transmit/Receive (T/R) unit A
and T/R unit B.  In A, the single oscillator is at frequency X, and
in B the single oscillator is at frequency X+DELTA.  In A, one uses a
cheap 1MHz oscillator, and imposes the FM modulation on it.  This
1MHz FM modulated signal is now the IF signal for an image reject
mixer which suppresses the low side image and carrier at X and
results in an FM modulated signal at X+1MHz.  In B, one uses a cheap
1MHz oscillator, and imposes the FM modulation on it.  This 1MHz FM
modulated signal is now the IF signal for an image reject mixer which
suppresses the high side image and carrier at X+DELTA and results in
an FM modulated signal at X+DELTA-1.  In the receiver in unit A, the
FM modulated...