a potential noise stability of radio engineering systems of an information transfer
The question on a potential noise stability of RTS of an information transfer is one of central in the signalling theory. The knowledge of a potential noise stability of RTS characterised by its extremely possible indicators, allows researchers and engineers to operate purposefully, taking into account existing reserves of increase of a noise stability and to avoid statement of incorrect problems. Not to know a potential noise stability of RTS or to ignore it is means to operate in this area blindly.
Exists two treatments of a potential noise stability of RTS of an information transfer: on Kotelnikovu and on Shennonu.
Criterion of a potential noise stability on Kotelnikovu is the minimum error in reception of a symbol of a binary combination or the minimum relation с/ш in a strip of the filter co-ordinated with a symbol. The potential noise stability is reached at coherent reception of a radio signal, i.e. at reception of a signal with a known initial phase.
As Criterion of a potential noise stability on Shennonu the relation с/ш, equal serves In a strip of the filter co-ordinated with a symbol of a binary combination at which achievement of as much as small probability of an error in reception of the signal equivalent in the information plan n – a digit binary combination is possible. The potential noise stability is reached at unlimited expansion of a strip of the frequencies, taken away to a signal.
The Potential noise stability on Shennonu can be realised at application of a signal with multiitem coding in which as a code sign frequency of fluctuations is accepted, and duration of a signal beyond all bounds increases with unlimited expansion a communication channel.
For an estimation of a potential noise stability on Kotelnikovu or on Shennonu it is supposed that the fact of a parcel of a signal is known a priori, and the reception equipment of system is served by the person. Therefore here false reception of a signal is not taken into consideration.
In the majority of RTS of transfer of discrete messages the criterion of optimum detection of Neumann-Pirsona as in them the fact of a parcel of a signal is unknown a priori is applied. With reference to such systems the new treatment of a potential noise stability as which criterion the greatest possible size of factor of the noise stability, received is offered at the set probability of false reception and duration of a multidigit signal is necessary.
The Potential noise stability on the given treatment is reached at performance of following conditions:
– coherent reception of a radio signal or reception on the co-ordinated strip filter with додетекторным signal decoding;
– application of the optimum signals possessing minimum пикфактором 1,0;
– absence in the scheme of reception and processing of a signal of nonlinear devices, except the terminator;
– unlimited expansion of a strip of the frequencies, taken away to a signal;
– signal processing as a whole.
In work analytical expressions for the greatest possible size of factor of a noise stability are received at processing binary ФТ a signal in whole and it поэлементной to processing. Transition to поэлементной to processing is accompanied by reduction of the maximum value of factor of a noise stability in time.
Unlike treatment of Kotelnikova, according to new treatment of a potential noise stability, its level received at work with ФТ by signals, can be reached also at work with ЧТ signals.