Engineering science / 2. Prospects of
information systems
Kulyk A.J., Krivogubtchenko S.G., Kulyk J.A.
Vinnitsa national technical university, Ukraine
Increase of
effective speed of transfer of the information
The rough development of
means of an exchange of the data in information systems of various
functionality requires increase of effective speed of transfer lost-free
information. Theoretically speed of transfer can not exceed Nickvist border,
which is defined by transfer of pulses 
[1].
But, in practice, the transfer of such pulses can
result in the too large amplitude of signals on the one hand, and with another – to the large intersymbolical distortions, and as a consequence – to loss of synchronization. By transfer of the information rectangular
pulses greatest possible will be half of Nickvist speed. In the literature the
principles of increase of speed of transfer of the information are considered
at the expense of use of pulses of the different form: rectangular and sine wave.
But thus on identification of the data the form of the received pulses essentially
influences. As it is necessary precisely to maintain the form of a rectangular
pulse, that, theoretically, it demands an infinite strip of frequencies of the
channel of communication. Practically this strip should be wide enough for the
passing of quantity of harmonics initial form, necessary for restoration, of a
pulse.
More effective represent
transfer of the information by pulses of the identical form (sine wave), but
moved in time, as it is submitted on the temporary diagrams (fig. 1). As more
often information transfers in a computer format (bytes), the informative code
combination totals eight binary digits. Irrespective of a mode of transfer
(synchronous or asynchronous), the first pulse should be individual, that it
was possible to begin from it readout of time intervals of identification. Thus
the signal acting in the communication line, is described by the formula
. (1)
Using a known ratio
,
(2)
вираз (1) можна подати у
вигляді:
|
Fig. 1 – The temporary diagrams of transfer of the
information by sine wave pulses with shift |
(3)
Proceeding from the received
ratio (3) it is possible to choose optimum meaning of a delay between pulses τ, so that a strip of
frequencies, which is borrowed by a signal, answered conditions of use of the
channel. The analysis shows, that the shift of pulses on a quarter of the
period 
leaves
in expression (3) only one component 
, that is the channel of communication will
transfer only one harmonic.
Fig. 2 – The block diagram for realization
of algorithm of increase of speed
of
transfer of the information
As during reception of the information
there is no necessity for complete restoration of the form of pulses, and the
task is reduced only to definition of amplitude of the signal which has come
from the channel of communication, in the fixed intervals of time, it will not
influence quality of transfer of the information absolutely. The speed of
transfer of the information thus grows in 1,5 times, and the capacity of a
signal in the channel of communication is not increased. The reduction of
parameter τ results on the one hand in increase of speed of transfer and approach to
Nickvist border, and with another – in the channel of
communication there are even harmonics and the capacity of a signal grows. At τ = 0 the
Nickvist border is reached, but the identification of signals becomes
impossible, and the capacity of a signal is increased in nine times. Thus, from
the point of view of a ratio capacity of
the channel / volume of a signal
optimum is shift of pulses 
.
Only Haar functions from all
class of wavelet-functions have a rectangular kind. Quasisine wave character
have Gauss wavelets of the even orders,
Daubechies wavelets and others [2]. Thanking orthogonal property it
allows to use them for construction of information systems, and the form – is essential to raise speed of transfer of the information.
Taking into account, that
the basic requirement during transfer is the concentration of energy in the
narrowest strip of frequencies [3],
such algorithm is most effective. The points of identification of a signal in
time are set by the timer, and the identification of a signal is defined by
comparison of its amplitude with threshold meaning at the precisely fixed
moments of time [4].
References.
1. Хармут
Х.Ф. Передача информации ортогональными функциями. – М.: Связь, 1975. – 272 с.
2. Дьяконов
В.П. Вейвлеты. От теории к практике. – М.: СОЛОН-Р, 2002. – 448 с.
3. Квєтний Р.Н.,
Компанець М.М., Кривогубченко С.Г., Кулик А.Я. Основи техніки передавання інформації.
– Вінниця: УНІВЕРСУМ-Вінниця, 2002 – 358 с.
4. Пат. 61383 України,
МПК7 Н03М 13/00. Спосіб передавання інформації та пристрій для його
здійснення / Кулик А.Я. (Україна); ВДТУ. – № 2003010392; заявл. 16.01.2003;
опубл. 17.11.2003; Бюл. № 11. – 7 с.