الفهرس 
Spread Spectrum SystemsOnly 14 pages are availabe for public view
 |  | from | 187 |  |  |
| | | from | 187 | | |
Abstract
The aim of this thesis is to study the design
procedures of a broadband quadriphase shift keying
( QPSK ) digital modulator, using finline techniques so
as to be applied in spread spectrum systems. Two
biphase shift keying modulators, one 1T and the other
11/2 areconnected in cascade to achieve the requi red
modulation.
The obtained modulator has a bandwidth of
about O.5GHz centered at lOGHz with phase deviation
o
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 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
performance that it agrees quite well with the obtained
measured results .