Process for transferring digital data via interference-affected

Details Process for transferring digital data via interference-affected Process for transferring digital data via interference-affected

1998-03-06

2000-10-10

Le, Amanda T.

Pulse or digital communications

Systems using alternating or pulsating current

Plural channels for transmission of a single pulse train

375299, 375340, 375347, 370343, 370345, 370485, 370498, H04L 108

Patent

active

06130915&

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is based on a method for transmitting digital data and a device for receiving digital data, especially audio and/or video data, including at least one radio program via noise-encumbered radio channels, wherein the data of the at least one radio program are modulated on at least one carrier wave and the data of one time segment of the at least one radio program are transmitted in one transmission frame. A method for transmitting digital data of an radio program via noise-encumbered radio channels is already known from an article by Georg Plenge, "DAB--ein neues Horrundfunksystem: Stand der Entwicklung und Wege zu seiner Einfuhrung" [DAB--A New Audio Radio System: State of Development and Ways of Introducing It], Rundfunktechnische Mitteilungen, Vol. 35, 1991, No. 2, pp. 45-66. In the transmission method described there, COFDM (coded orthogonal frequency division multiplexing) is employed. In it, a cluster of six radio programs, for instance, is transmitted at an assigned frequency block with a bandwidth of 1.5 MHz. However, whichever time segment of a radio program is transmitted is transmitted only a single time.
A radio system for transmission of information entities which is subject to noise during transmission is described in WO-A-9 506 368, in which the information entities to be transmitted are modulated on the same carrier frequency in the form of two parallel, but temporally shifted, transmitted data flows. During reception of both parallel transmitted data flows by means of a suitable detector, whether or not and if necessary which of both data flows are subjected to interference during their transmission is detected. On the receiver end then the information entities interfered with during the course of the transmission are replaced by the time displaced and thus usually undisturbed information entities in the time displaced transmitted data flow.


SUMMARY OF THE INVENTION

According to the invention, the method of transmitting digital data including at least one radio program via noise-encumbered radio channels comprises modulating data of the at least one radio program in complex form on at least one carrier wave; transmitting data of a time segment of the at least one radio program in a transmission frame; repeating at least once transmission of the data of the time segment of the at least one radio program and adding together complex values obtained in a demodulator of the at least one carrier wave for individual transmissions generated in the transmitting and repeating to obtain reliable decision variables regarding a modulation state of the at least one carrier wave.
The method of the invention has the advantage over the prior art that for certain radio programs, a repeat transmission of the same time segment of the radio program is contemplated. This is followed by a common evaluation of the data transmitted first and the data transmitted in the repetition for one time segment of the radio program. The repeat transmission of the same time segment of a radio program adds redundancy to the data stream. The receiver of the radio program can utilize this redundancy at little additional effort or expense. The method offers advantages particular for mobile reception in a moving car. For instance, if the car is moving at the limits of the broadcast range, there will be increased interference, which can lead to incorrect evaluations of the transmitted data.
Increased interference can be due to multi-path transmission. Repeating the transmission of the same data using a time division multiplexing process now markedly increases the immunity to interference. In all probability, in fact it will no longer be the same data as in the previous transmission that have interference. This fact can be exploited in the receiver, and in the demodulation a sort of mean value of the single transmissions can be formed that then has greater immunity to interference.
Naturally the data transmission capacity of the radio channel is reduced by the repeat transmission of the sam

REFERENCES:
patent: 4881241 (1989-11-01), Pommier et al.
patent: 5784418 (1998-07-01), Sykes et al.
patent: 5949796 (1999-09-01), Kumar
"A Double Nyquist Digital Product Detector for Quadrature Sampling", by Leopold E. Pellon, IEEE Transactions on Signal Processing, vol. 40, No. 7, Jul. 1992, pp. 1670-1681.
"Principles of Modulating and Channel Coding for Digital Broadcasting for Mobile Receivers", by A. Alard and R. Lassalle EBU Review, Technical No. 224, Aug. 1987, pp. 168-190.
"DAB-Ein Neues Hoerrundkunksystem Stand Der Entwicklung Und Wege Zu Seiner Einfuehrung", by Georg Plenge, Rundfunktechnische Mitteilungen, Heft 2, Jahrgang 35, 1991, pp. 45-46.

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