JPH02192333A - Voice signal transmission system - Google Patents

Abstract

PURPOSE:To recover a voice signal of wide dynamic range and to secure interchangeability with reception equipment for main transmission path by transmitting an original voice signal via a main transmission path after applying bit compression, and transmitting a remaining high frequency component via a subtransmission path. CONSTITUTION:A transmission signal for main transmission path is converted to a signal (a) in which the original voice signal is bit-compressed by a bit compression circuit 1, and is sent via a signal delay circuit 2. Also, the transmission signal to be sent to the subtransmission path on an encoder side can be obtained as a demodulation signal (b) demodulated from the output signal (a) bit-compressed at the bit compression circuit 1 via a demodulator 3. The differential signal (d) of the signal (b) and a signal (c) from a signal delay circuit 4 is sent via a differentiator 5. Namely, by transmitting the voice signal with high quality of wide dynamic range on the main transmission path after applying the bit compression, and transmitting a signal component not being transmitted after applying the bit compression at the subtransmission path, and attaching it at a reception side, the voice signal of wide dynamic range can be recovered, and also, the interchangeability with the reception equipment for main transmission equipment can be secured.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is a method for receiving audio signals for the main transmission line, which has a larger amount of information (wide dynamic range) than can be transmitted by the transmission capacity of the main transmission line. The present invention relates to an audio signal transmission method that is compatible with a device and transmits it via a main transmission path and a sub-transmission path, and its transmitting and receiving device.

(Summary of the Invention) This invention relates to a system for transmitting audio signals via two transmission paths, in which the audio signal given on the main transmission path is bit-compressed and transmitted, and the sub-transmission path is used to transmit the audio signal on the main transmission path. In addition to transmitting the signal deleted by bit compression, the receiving side demodulates and adds the signals transmitted on both transmission paths in compatibility with the main transmission path receiving device.

By doing this, it is possible to restore the original audio signal with an improved dynamic range compared to when only the main transmission path is used, and even a receiving device for the main transmission path that does not have reception equipment for the sub transmission path can receive the service of this audio signal. Can be done.

(Prior Art) Conventionally, there was a technology in which an audio signal is divided and transmitted via multiple transmission paths, and the received signals are added together to reproduce the original audio signal, but the method of the present invention There was no system for dividing transmission that is compatible with the main transmission path receiving device, which alone can provide sufficient sound quality.

(Problem to be Solved by the Invention) The conventional divisional transmission method was designed to transmit a high-quality audio signal with a large amount of information by combining several transmission paths with low transmission capacity. Since the system was also simple, if a transmission failure occurred in one of the multiple transmission lines used, information could not be transmitted correctly.

Therefore, the present invention solves the above-mentioned problems and can transmit information with almost sufficient sound quality using only the main transmission path, but additionally transmits high-quality information that cannot be transmitted on the main transmission path via the sub-transmission path. Therefore, it is an object of the present invention to provide an audio signal transmission system and its transmitting/receiving apparatus that can reproduce the original audio signal with a wider dynamic range than can be obtained using only the main transmission path on the receiving side.

(Means for Solving the Problem) In order to achieve this objective, the audio signal transmission system of the present invention:
- The original audio signal having a larger amount of information than can be transmitted by the transmission capacity of the main transmission path is transmitted via the main transmission path and the sub-transmission path, and on the receiving side, the original audio signal is transmitted through the main transmission path. In order to restore an audio signal having a larger amount of information from a signal that is compatible with the receiver and transmitted over both transmission lines, the transmitter side must convert the original audio signal to a bit compression circuit. On the other hand, the difference between the original audio signal and the signal demodulated from the output signal via the bit compression circuit is sent to the sub-transmission path, and on the receiving side, the signal is sent to the main transmission path The audio signal is restored by adding the difference signal transmitted through the sub-transmission path to the audio signal demodulated from the signal transmitted through the main transmission path, producing a reproduced audio signal with a wider dynamic range than when using only the main transmission path. It is characterized by the fact that it can be obtained.

Further, the audio signal transmitting device of the present invention is a transmitting device used in the above transmission method, and the device includes a bit compression circuit, a first demodulator that demodulates the output of the bit compression circuit, and a first demodulator that demodulates the output of the bit compression circuit. A signal delay circuit for adjusting the phase of the first output signal and the original audio signal, and a subtraction circuit that takes the difference between the second output signal of the signal delay circuit and the first output signal. This is a characteristic feature.

Further, the audio signal receiving device of the present invention is a receiving device used in the transmission method, and the device also includes a second demodulator for demodulating the audio signal from the signal transmitted on the main transmission path. , and an adder that adds the difference signal transmitted through the sub-transmission path to the output signal of the second demodulator.

(Function) According to the transmission method of the present invention, the amount of information that cannot be transmitted by the transmission capacity of the main transmission path, specifically, the original audio signal having a wider dynamic range, is bit-compressed and transmitted through the main transmission path. , and the remaining high-frequency components are transmitted via the sub-transmission line, so it is compatible with the main transmission line receiver, and even if a transmission failure occurs on the sub-transmission line, the sound quality will be maintained to some extent. It is possible to reproduce the recorded audio signal.

(Example) The invention will now be explained by way of examples with reference to the accompanying drawings.

FIGS. 1 and 2 respectively show schematic configuration diagrams of a transmitting side encoder and a receiving side decoder according to the transmission system of the present invention.

It is assumed that the original audio signal input to the encoder shown in FIG. 1 is a high-quality audio signal having a wide dynamic range. The transmission signal for the main transmission line is an original audio signal which is converted into a bit-compressed signal a by a bit compression circuit 1 and sent out via a signal delay circuit 2.

Here, the bit compression circuit 1 may be a known instantaneous or quasi-instantaneous compression encoding means or instantaneous or quasi-instantaneous compression differential encoding means for the purpose of compressing a so-called dynamic range. Among these, quasi-instantaneous compression differential encoding means are disclosed in Japanese Patent Application Laid-open No. 63-16718, "Quasi-instantaneous compression differential encoding method" and Japanese Patent Application Laid-Open No. 63-292722, "Correction type quasi-instantaneous compression differential encoding method." ” is there. Regardless of the compression encoding method or the compression differential encoding method, range bits are added to the compressed digital signal to compress the dynamic range, so even if only this signal transmitted through the main transmission path is used, Audio signals whose quality is guaranteed to some extent can be reproduced. However, in order to reproduce on the receiving side the original high-dynamism range signal that is quasi-discarded using this bit compression circuit, additional information is required. It is transmitted by road.

The signal delay circuit 2 described above is originally a delay circuit for synchronizing the timing of sending signals to the main transmission path and the sub-transmission path on the encoder side, but the second decoder shown in the figure When adding the signals from adder 6,
If the timing adjustment is adjusted in advance using the signal delay circuit 2, there is no need to provide a signal delay circuit on the decoder side again, making it convenient for mass production of decoders.In this embodiment, the timing adjustment can be adjusted in advance. shall be included.

Next, the transmission signal sent to the sub-transmission path on the encoder side is
First, a demodulated signal b (first output signal) is obtained by demodulating the output signal a bit-compressed by the bit compression circuit 1 through the demodulator 3 (first demodulator). In order to adjust the timing, a difference signal d is obtained between the signal C (second output signal) passed through the signal delay circuit 4 and the difference signal d via the subtractor 5, and this difference signal d is sent out.

In the receiving side decoder shown in the second diagram, the signal transmitted via the main transmission path is demodulated by the demodulator 7 (second demodulator) and becomes a signal. Further, the difference signal d transmitted through the sub-transmission path and the demodulated signal S described above are added together by an adder 6 to produce a high-quality original audio signal. In the case of only the output signal from the demodulator 7, it is used for the main transmission path receiving device.

(Effects of the Invention) As explained above in detail, in the audio signal transmission method of the present invention, bit compression is performed on a high quality audio signal with a wide dynamic range on the main transmission path, and only the dynamic range is compressed and transmitted. Therefore, almost satisfactory sound quality can be ensured with information from only this main transmission path, and the signal components that could not be transmitted due to bit compression are transmitted on the sub transmission path, and the signal transmitted on the main transmission path is transmitted on the receiving side. Since it is added to the signal, it is possible to restore wide dynamic audio signals. Furthermore, even if a transmission failure occurs on the sub-transmission path, a reasonable level of sound quality can be ensured on the receiving side. Furthermore, compatibility with the main transmission path receiving device can also be ensured.

[Brief explanation of the drawing]

FIGS. 1 and 2 respectively show schematic configuration diagrams of embodiments of a transmitting side encoder and a receiving side decoder according to the transmission system of the present invention. 1...Bit compression circuit 3.7...Demodulator 6...Adder 2.4...Signal delay circuit 5...Subtractor Patent applicant

Claims (1)

[Claims] 1. An original audio signal having a larger amount of information than can be transmitted by the transmission capacity of the main transmission path is transmitted via the main transmission path and the sub-transmission path, and is sent to the receiving side. In order to restore an audio signal having a larger amount of information from a signal that is compatible with the main transmission path receiving device and transmitted on both transmission paths, the transmitting side must The audio signal is sent to the main transmission path via the bit compression circuit, and the difference between the original audio signal and the demodulated signal outputted from the bit compression circuit is sent to the sub-transmission path, and the difference is sent to the receiving side. If so, the audio signal is demodulated from the signal transmitted through the main transmission path, and the difference signal transmitted through the sub-transmission path is added to restore the audio signal. An audio signal transmission method characterized by obtaining a reproduced audio signal with a dynamic range. 2. The audio signal transmission system according to claim 1, wherein the bit compression circuit is instantaneous or quasi-instantaneous compression encoding means. 3. The audio signal transmission system according to claim 1, wherein the bit compression circuit is instantaneous or quasi-instantaneous compression differential encoding means. 4. A transmitting device used in the transmission system according to any one of claims 1 to 3, the device comprising a bit compression circuit, a first demodulator that demodulates the output thereof, and the first demodulator. a signal delay circuit for phase matching the first output signal of the device and the original audio signal, and a subtraction circuit for calculating the difference between the second output signal of the signal delay circuit and the first output signal. An audio signal transmitting device characterized by: 5. A receiving device used in the transmission method according to any one of claims 1 to 3, wherein the device demodulates an audio signal from a signal transmitted on the main transmission path. and an adder that adds the difference signal transmitted through the sub-transmission path to the output signal of the second demodulator.