posted on 2013-04-10, 12:54authored byJohn D. Harvey
The thesis describes various detection processes which are suitable
for use in a synchronous serial data-transmission system operating at a
transmission rate of up to 20,000 bits per second over a slowly time-varying
channel, The methods of operation of different detection processes are
first described, with reference to binary and quaternary baseband
signals, which includes the case when V,S,B,signals are transmitted over
·telephone circuits or H,F,radio links. The results of computer simulation
tests are presented, comparing the tolerances of the detection processes
to additive white Gaussian noise with the tolerances of conventional
linear and non-linear equalisers. Several different time invariant
channels are used in the tests. It is shown that two relatively simple
detection processes can achieve a considerable improvement in tolerance
to noise over both linear and non-linear equalisers of optimum design,
Several of the most promising detection processes and a few new
detection processes are then modified to use 4-point, 16-point and
32-point Q,A,M,signals. The methods of operation of the different
detection processes are then described for the signal format being
considered. The results of computer simulation tests are presented
comparing their tolerances to additive white Gaussian noise with those ·
of the linear and non-linear equalisers of optimum design.
It is shown that these detection processes operate most efficiently,
in terms of tolerance to noise and in the number of sequential operations,
if the transmitted signal contains the smallest number of possible
signal levels.
Finally, several simple methods of estimating the sampled impulse
response of the channel are presented. One of these channel estimation
techniques gives a very low error in the estimated response, while giving
a good rate of adaptation to a time-varying channel.
History
School
Mechanical, Electrical and Manufacturing Engineering