RU2513116C2 - Method of generating digital broadcast signal - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to a method of transmitting signals, primarily broadcast signals. Disclosed is a method of generating a digital broadcast signal, which involves sampling/generating analogue signal readings, level quantisation of the readings and converting the level quantisation results to a digital signal, wherein the number of readings is increased during level quantisation, and sampling frequency is halved when generating analogue signal readings, while maintaining the bit rate.

EFFECT: high quality of the reconstructed signal while maintaining the number of digital sound broadcasting channels in a common digital stream.

Description

The present invention relates to a method for transmitting mainly broadcast signals.

Known methods for transmitting broadcast signals at which a temporary sampling of an audio signal is carried out with a frequency corresponding to a frequency determined by Kotelnikov’s theorem, and then quantizing the samples by level and generating a digital signal whose bit depth is determined by the number of quantization levels (See I. Aldoshin, “Electroacoustics and sound broadcasting. ”M.: Telecom, 2007, p. 480-485) (1). It is known that, according to Kotelnikov’s theorem, for complete signal recovery, the temporal sampling frequency should be twice as high as the highest signal frequency. However, the transfer is not directly subject to time readings, but their expression in digital form, i.e. digital signal is transmitted.

To obtain a digital signal, quantization is carried out at a level at which errors in the amount of half the quantization step are inevitable, and therefore, at reception, the signal is restored in a distorted form. To reduce errors, a decrease in the quantization step is required, however, to transmit the results, it is necessary to increase the bit depth of the digital signal, which in turn will lead to an increase in the speed of the digital stream.

Digital bit rate is defined as

$$V=n\times F_d\text{(one)}\text{,}$$

where V is the transmission speed, n is the bit depth of the signal and F _d is the sampling frequency.

An increase in the transmission rate of the digital signal, which leads to a decrease in the number of digital audio channels in the overall digital stream.

The technical result of the invention is to improve the quality of the reconstructed signal while maintaining the number of digital audio channels in the total digital stream.

To achieve the indicated technical result, a method for generating a digital broadcast signal is proposed, which consists in sampling — generating samples of analog signals, quantizing samples by level and converting the results of quantization of samples by level into a digital signal, characterized in that they increase the number of samples when quantizing samples by level, and the formation of samples of analog signals is carried out with a frequency half that of the frequency determined by the Kotelnikov theorem and the number of bits Frova dual signal.

When transmitting audio broadcasting signals, the ability to listen to natural noise is of great importance for signal perception. The absence of natural noise in the channel (for example, in the phone) leads to the fact that the subscriber perceives this as a disconnection with all the ensuing consequences. When broadcasting concerts from concert halls, the absence of natural noise leads the listener to the impression that the broadcast is from a recording studio. This is due to the large quantization step in terms of the level at which natural noise is perceived as the absence of a signal.

When doubling the number of bits of a digital signal, it becomes possible to reduce the quantization step by orders of magnitude, which makes it possible to increase the accuracy of signal reconstruction. At the same time, reducing the sampling rate allows you to save the transmission speed

Of course, this is the well-known Archimedean rule of “leverage” - we lose in something, we win in something, but tests have shown that the signal generated according to the present method has objectively better quality when reproducing audio broadcasting signals.

Claims (1)

A method of generating a digital broadcast signal, which consists in sampling-generating samples of analog signals, quantizing samples by level and converting the results of quantization of samples by level into a digital signal, characterized in that it is possible to listen to natural noise to perceive the transmission of sound broadcasting by increasing the number of samples during quantization samples by level and number of digits of a digital signal, and when forming samples of analog signals, the frequency is halved sampling, maintaining the speed of the digital stream V = nF _d , where n is the bit depth of the digital signal, and F _d is the sampling frequency.