Mostrar nube de etiquetas

Hitherto communication theory was based on two alternative methods of signal analysis. One is the description of the signal as a function of time; the other is Fourier analysis. Both are idealizations, as the first method operates with sharply defined instants of time, the second with infinite wave-trains of rigorously defined frequencies. But our everyday experiences -especially our auditory sensations- insist on a description in terms of both time and frequency. In the present paper this point of view is developed in quantitative language. Signals are represented in two dimensions, with time and frequency as co-ordinates. Such two-dimensional representations can be called "information diagrams", as areas in them are proportional to the number of independent data which they can convey. This is a consequence of the fact that the frequency of a signal which is not of infinite duration can be defined only with a certain inaccuracy, which is inversely proportional to the duration, and vice versa. This "uncertainty relation" suggests a new method of description, intermediate between the two extremes of time analysis and spectral analysis. There are certain "elementary signals" which occupy the smallest possible area in the information diagram. They are harmonic oscillations modulated by a "probability pulse". Each elementary signal can be considered as conveying exactly one datum, or one "quantum of information". Any signal can be expanded in terms of these by a process which includes time analysis and Fourier analysis as extreme cases.These new methods of analysis, which involve some of the mathematical apparatus of quantum theory, are illustrated by application to some problems of transmission theory, such as direct generation of single sidebands, signals transmitted in minimum time through limited frequency channels, frequency modulation and time-division multiplex telephony.

Notas/Comentarios de J.A.Delgado-Penín:
Primer artículo de una colección de tres partes del mismo autor sobre una teoría de la señal anterior al planteamiento de C.E. Shannon. Este autor es el mismo que inventó la holografía e hizo contribuciones también a las comunicaciones ópticas. En esta Pt. 1 se plantea por primera vez el concepto y modelo matemático de una descripción de una señal eléctrica en los dominios del tiempo y de la frecuencia contemporáneamente. Se propone una fórmula que asemeja a la del principio de indeterminación de Heisemberg de la mecánica ondulatoria; pero sin ninguna relación con la misma. D. Gabor creó lo que él llamó "information diagrams" para crear una teoría matemática de la señal y postuló el "logon" o unidad de información y que no tiene caracterización probabilista. Ver los artículos seminales de GABOR.

Especificaciones

  • Autor/es: Dennis Gabor.
  • Fecha: 1946-11
  • Publicado en: Journal of the Institution of Electrical Engineers (Volume 93, Issue 26, November 1946, p. 429-441).
  • Idioma: Inglés
  • Formato: PDF
  • Contribución: José Antonio Delgado-Penín.
  • Palabras clave: Proceso de señal
Foro

Foro Histórico

de las Telecomunicaciones

Contacto

logo COIT
C/ Almagro 2. 1º Izq. 28010. Madrid
Teléfono 91 391 10 66 coit@coit.es
logo AEIT Horizontal
C/ General Arrando, 38. 28010. Madrid
Teléfono 91 308 16 66 aeit@aeit.es

Copyright 2022 Foro Histórico de las Telecomunicaciones