FR2643204A1 - Device for decoding an audio transmission system into several coded languages and a system for audio coding into several languages - Google Patents

Abstract

The invention relates to a device making it possible to use a single audio transmission channel for all languages with a single receiving device. It consists of a coder comprising a multiplexing circuit 1, controlled by a counting control circuit 4, and a staircase-generating system 3. The signals from the circuits 1 and 3 are then added together by means of the mixing circuit 2 in order to yield the coded audio signal. The decoder then receiving these coded information items via a single channel will reshape the signal with the aid of an input circuit 5 and send it to a circuit for monitoring the sampler 6, and to a sampler 7. The signal thus sampled is followed by an amplifying filter 8 so as to accord the signal an amplitude sufficient to allow it to be listened to. The device according to the invention is intended for tourists, enabling them to listen to a talk in their own language during visits to cultural sites.

Description

DEVICE FOR DECODING AN AUDIO TRANSMISSION SYSTEM INTO
MULTIPLE ENCODED LANGUAGES AND AN AUDIO ENCODING SYSTEM IN
MANY LANGUAGES.

 The present invention relates to the field of so-called coded sound, and more specifically relates to a device for decoding an audio transmission system in several coded languages and thus to an audio coding system in several languages.

 The transmission of each language is traditionally carried out separately and received by a separate device for each language.

 The object of the invention, yes is the subject of the present application, is to allow the use of a single transmission channel for all languages, thus giving each person the possibility of choosing their own language with a device. single reception. To do this, we will have an encoder comprising a staircase generator, ascending or descending, -whose we will assign, for each step, a separate language and to which we will add a fraction of the signal of each language corresponding to it.

 The information, thus coded, will be transmitted to the decoder by a single channel. The decoding of the information thus coded will be done by sampling the coded signal. A window comparator will have voltage values corresponding to the chosen language on its reference inputs, and will also receive the coded signal. When the step corresponding to the chosen language is between the reference values of the comparator, the comparator will command a sampler which will store the voltage value of the level.

 This voltage value will then be filtered by a series of "Low Pass" filters, then amplified so as to be audible to the user.

The invention relates for this purpose in a coded sound transmission system, con successively take
- A coding device (I) characterized by a counting circuit (5) delivering a binary BCD code to a multiplexing circuit (2), as well as to a staircase generator system (6) .

 The signal from the multiplexing circuit (L) is then added to the signal from the staircase generator system (6) using the mixing circuit (7) to give the final coded audio signal.

 - A transmission channel (2) of the information thus coded.

 - A decoding device (3) characterized by an input circuit (8) giving the correct values to the coded signal, for cue the sampler control circuit (9) activates the sampler (I0) when the value of coded signal ccrrescond to the chosen language.

 The signal thus sampled is then filtered and amplified by the amplifier filter (II) to give the audio signal in the chosen language.

 A) Device characterized in that the multiplexing circuit (2) itself comprises eight pre-emphasis amplifiers (I2) to (19) connected to an analog multiplexer (20), the latter being controlled by a translator (21) to give an audio signal multiplexed from the eight languages to be coded, and a modulation control circuit (22) making it possible to display the presence of these modulations of each language.

 B) Device characterized in that the counting control circuit (5) comprises a clock (23) delivering a precise signal in frequency to a divider counter (24), this giving the clock signal to the binary counter (25) so that 'it delivers the signals B, C, D necessary for coding.

 C) Device characterized in that the staircase generator system (6) consists of a current generator (26) controlling the amplitude of the steps of the general staircase (27), the signal of which is running staircase is buffered by the buffer amplifier (2).

 D) Device characterized in that the mixing circuit (7) includes a buffer amplifier 2 (29) separating the multiplied signal from the additions of the addition circuit (30) which also receives the signal in staircase steps. The signal thus coded is transmitted to the pre-emphasis circuit (3I).

 E) Device characterized in that the input circuit (9) is composed of a fixed voltage generator (32) controlling the offset of the input amplifier (33).

 F) Device characterized in that the control circuit of the sampler (9) comprises a current generator (34) allowing the language selector (35) to supply two reference voltages to the window comparator (36). Said window comparator (36) then provides a service pulse, when the coded signal, corresponding to the chosen language, is between the two references, which is sent simultaneously to the circuit for formatting the control signal ( 37) and to the negative voltage generator (38).

 The two signals are then added using the summator (39) to give the sampler control signal.

 G) Device characterized in that the sampler (I0) comprises a sampler (40) with memory.

 H) Device characterized in that the amplifier filter (II) comprises a "Low Pass" filter (41), and a "Low Pass" filter (42) for eliminating the high frequencies of the sampled signal, as well as an amplifier audio frequency (4-3) giving the audio signal sufficient amplitude to allow listening.

The features and advantages of the invention will now appear in a more precise manner in the description which follows and in the attached drawings in the drawings.
- Figure I is a very schematic view of the complete transmission system. This therefore includes a system of
Coding (I) transmitting the coded information to the Decoder (3) through the Channel (2).

 - Figures 2 and 3 show the different blocks making up the Encoder (I) and the Decoder (3).

 - Fiourses Z and 5 show, in detail, the constituent elements of the Encoder (I).

 - Figure 6 shows, in detail, the constituent elements of the Decoder (3).

With reference to these drawings
- The Encoder (I) includes
A) A multiplexing circuit (4) includes eight @ accentuating amplifiers numbered from (12) to (19), which have the function of bringing the input signal of each language to a level of + 10 dB relative to the level of reference
O c.-, with a pre-emphasis constant T ^ U equal to 300 S.

These are then directed to the modulation control circuit (22), making it possible to verify that there is an audio signal on each channel, and to a multiplexer (20), controlled by a tramslator (21). even controlled by the counting control circuit delivering the operating sequence using this three-bit B, C, D. The audio signals of each channel, thus multiplied, are recovered on output A.

B) A counting control circuit (5), the role of which is to give the order and the rate of counting, comprises:
a) A clock (23) giving a stable frequency to the coding system.

 b) A divider counter (24) which divides the clock frequency by ten.

c) A binary counter (25) receiving, on its clock input, the regional from the divider counter (24) and delivering on its outputs the three control bits
B, C, D necessary for the generation of coding.

C) A staircase generator system (6) comprising a current generator (26) which delivers a constant current to control the amplitude of the generator steps
This staircase steps (27), this cui will align each language of the multiplexed audio signal, on a precise voltage value. The staircase generator receives, in addition, the information B, C, D of the counting circuit allowing it to generate the signal in the form of staircase steps.

 The signal is then buffered by the buffer circuit (28) yes G short role of avoiding that the staircase generator is not disturbed in its operation by an excessive load of the following circuits.

 D) A mixing circuit (7) comprises an addition circuit (30) summing the multiplied signal of the runs of the buffer (29), with the signal in the form of a staircase step of the buffer (26) to give the definitive coded signal necessary for the transmission of the eight lanaues.

 The signal signal is then transmitted to a precontrolling amplifier (3I) bringing the amplitude of the coded signal to + 7.5 dB relative to the reference level of O dB, and giving it a pre-quantification value TAU ecala 40, uS, so that the transmission line is properly attacked.

- The decoder (3) includes:
A) An input circuit (8) made from an amplifier (33) and a fixed voltage generator (32) making it possible respectively to bring the amplitude of the coded signal to a value of + 5.65 dE compared to the reference level of O dB and to align this same signal on a precise voltage value corresponding to the proper functioning of the decoder.

 The signal, thus formatted, is then directed to a sampler and a control circuit of the sampler.

B) A sampler control circuit (9) generates the control signal when the value of the level of the coded channel corresponds to the chosen language. I1 therefore includes for this purpose:
e) A language selector (35), receiving from a current generator (34) a constant current, allows it to manufacture two precise and different reference voltages, according to the language chosen by the user of the system.

 b) A window comparator (36) receives the two reference voltages from the screen selector (35) and the coded signal from the amplifier (33). When the value of the level of the coded signal is between the two reference values of the window comparator, the latter delivers a service pulse which will then be used to control the sampler.

 c) A circuit for shaping the control signal (37) gives the service pulse of the window comparator an amplitude and a fixed width for the proper functioning of the sampler.

 d) A negative voltage generator (38) uses the service pulse to produce a negative voltage necessary for blocking the sampler.

 e) A summing circuit (39) adds up the service pulse reshaped by 7 circuits (37) with the negative voltage produced by the circuit (3S) to give the final triggering signal of the sampler.

 C) A sampler with memory (40) takes the value of the coded signal at the moment when the service pulse, produced using the sampler control circuit, is activated. This value is then stored in memory and filtered using two "Low Pass" filters (41) and (42), having respectively a slope of I2 dB / Oct2ve and a cutoff frequency of KHz for the filter (41 ), and 6 dB / Octave and a cutoff frequency of 8 KHZ for the filter (42). The signal, thus filtered, is transmitted to the amplifier (43), which brings the said signal to a voltage value sufficient to control an earphone or the desired audio message can be heard, and in the language chosen from the eight available .

 Of course, the present invention is not limited to the embodiment described above and shown, with ducuel mortar variants of the Encoder, or the Decoder can be proposed without departing from the scope of the invention.

Claims (6)

1- A coded sound transmission system successively comprising:  - A Coding device (I) characterized by a counting control circuit (5) delivering a binary code B, C, D to a multiplexing circuit (4), as well as to a staircase generator system (6).  The signal from the multiolexing circuit (4) is then added to the signal from the staircase generator system (6) using the mixing circuit (7) to give the final coded audio signal.  - A transmission channel (2) of the information thus coded.  - A Decoding device (3) characterized by an input circuit (8) giving the correct values to the coded signal, for cue the sampler control circuit (9) activates the sampler (IO) when the value of coded signal corresponds to the language chosen.  The signal thus sampled is then filtered and amplified by the amplifier filter (II) to give the audio signal in the chosen language.  Device according to Claim I, characterized in that the multiplexing circuit (4) itself comprises eight pre-accentuating amplifiers (I2) to (19) connected to a multiple analog xer (20), the latter being controlled by a translator (21 ), to give a multiplexed audio signal of the eight E coding languages, and a modulation control circuit (22) make it possible to visualize the presence of modulations of each language. 3- Device according to claim I characterized in that the counting control circuit (5) comprises a clock (23) delivering a precise frequency signal to a divider counter (24), the latter giving the clock signal to the binary counter (25) for where it delivers the necessary B, C, D signals = u Coding. 2- Device according to claim I characterized in that -! Ue the staircase generator system (6) consists of a current generator (26) controlling the amplitude of the steps of the staircase generator (27), whose staircase signal is buffered by the buffer amplifier (28). 5- Device according to claim I characterized in that the mixing circuit (7) comprises a buffer amplifier 2 (29) separating the signal multiplied from the languages of the addition circuit (30) which also harms the signal in steps staircase. The signal thus coded is transmitted to the pre-emphasis circuit (31). 6- Device according to claim I characterized in that the input circuit (b) is composed of a fixed voltage generator (32) controlling the offset of the input amplifier (33). 7- Device according to claim I characterized in that mua the control circuit ae the sampler (g) comprises a current generator (34) allowing the langa oe selector (35) to provide two reference voltages to the window comparator ( 36). Said window comparator (36) then provides a service pulse, when the coded signal, corresponding to the chosen language, is between the two references, which is sent simultaneously to the circuit for shaping the control signal (37) and the negative voltage generator (38).  The two signals are then added using the summator (3a) to give the sampler control signal.  - Device according to claim I characterized in that the sampler (10) comprises a sampler (40) with memory.  c, Device according to claim I characterized in that the amplifier filter (II) comprises a "Low Pass" filter (41) and a "Low Pass" filter (42) for eliminating the high frequencies of the sampled signal, as well as an audio frequency amplifier (43) giving the audio signal a sufficient amplitude to allow it to be listened to.