الفهرس 
Spread Spectrum SystemsOnly 14 pages are availabe for public view
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Abstract
The aim of this thesis is to study the
procedures of a broadband quadriphase shift
( QPSK ) digital modulator, using finline techniques so
as to be applied in spread spectrum systems. Two
b i phase shift keying modulators, one ’TT and the other
’11/2 are connected in cascade to achi eve the requ ired
modulation. The obtained modulator has a bandwidth of
about O.5GHz centered at lOGHz with phase deviation
. .
less than.±. 7 and a reflection loss variation not more
than O.8db.
The thesis discusses the different spread spectrum
modulating
techniques, their
advantages
and
disadvantages.
A survey is also given about the two
main classes of high speed codes used in spread
spectrum systems.
This survey studies the properties
and capabilities of these codes as well as the
coders/decoders used for their generation/regeneration.
An introduction is
then presented to the design of
broadband QPSK reflection type modulators used in
spread spectrum systems. A modulator is realized with
·circulators,
switching PIN diodes and impedance
design
keying matching networks having filter structures. Finally,the
practical realization of the QPSK modulator using
finline techniques is given.
The measurements and
results of the modulator circuit using a network
analyzer are obtained. It is noticed from the design
performanGe that it agrees quite well with the obtained
measured results.