DE3405493A1 - Multiplex method for digital transmission of stereo sound signals via devices of the standardised PCM hierarchy - Google Patents

Abstract

In order to be able to transmit up to two digital multiplex signals DS1 and DS1' in each case at a bit rate of 992 kbit/s, in each case containing a high-quality digitised and error-protected stereo sound signal with associated additional information and their own frame alignment words, via a DSV2 (formerly PCM30), the odd-numbered time channels 1, 3, ..., 31 are occupied according to the invention with the first multiplex signal DS1 and the even-numbered time channels 2, 4, ..., 30 are occupied with the second multiplex signal DS1', the first multiplex signal DS1 occupying only 6 bits in the time channels 1 and 31 and the second multiplex signal DS1' also occupying the respective remaining 2 bits in these time channels 1 and 31. Instead of the second multiplex signal DS1', 14 telephony channels can be transmitted in the even-numbered channels 2, 4, ..., 14, 18, 20, ..., 30 and the signalling channel which is then required can be transmitted in time channel 16. A freely available bit within the service words of the DSV2 carries, as the clock alignment bit, the clock alignment type of the positive-zero-negative clock alignment method used here (Fig. 2). <IMAGE>

Description

The invention relates to a method for transferring

at least one digital multiplex signal with a bit rate of 992 kbit / s, which is a high-quality, digitized and error-proof stereo sound signal with associated additional information as well as its own code words, in particular between individual broadcasters and broadcasting stations, such as. B. satellite earth stations, as well as between broadcasters among each other (also internationally).

It is known that high-quality stereo audio signals are used in the transmission network German Bundespost analogue or already digitally transmitted. This here The digital system used with analog inputs and outputs is in the paperback of the Telecommunications practice described in 1979. The clock for digital signal processing is derived exclusively from the clocks of the digital transmission links. the end For this reason and also because of the analog interfaces, there are no synchronization problems whatsoever in the national and international program exchange.

If the transmission is to be purely digital in the future, it cannot it is expected that a synchronous network will soon exist worldwide, of from which all studios can be synchronized with regard to their clock. The introduction a synchronous nultiplex transmission technology therefore appears risky. Much more timing adjustment procedures should be provided that can be used later without replacing the Device technology also enable synchronous operation.

Assuming a future synchronous digital telephone network the first PCM hierarchy level, so-called 2 Mbit / s digital signal connections (DSV2, earlier Po30), then you can learn about the necessary clock rates omitted because the clock signals for the analog / digital conversion of the audio signals are immediate of the Clock of the DSV2 (2048 kHz) derived within this network will.

For the transitional period in which only a plesiochronous digital telephone network from z. B. several not mutually synchronized 1) SV2 exists and for an international program exchange are through the German OS 29 47 226 and 29 47 227 two clock adjustment methods are known, which are achieved by bit or word-by-word clock adjustment enable plesiochronous operation. The disadvantage of this method is that only 11 bits are available for coding the sample values of the audio signals, no additional information associated with the audio signals can be transmitted and that the code words of the audio signals are firmly integrated into the pulse frame of the DSV2, see above that the digitized audio signals cannot be used as independent digital signals without additional and elaborate. Synchronization e.g. B. forwarded within the broadcaster and can be decoded.

The German OS 29 48 435 describes a likewise from the applicant Proposed method in which the samples as 14-bit code words over a DSV2 are transmitted. The disadvantages with this method are that only one error protection bit each four code words is assigned that no additional information is transmitted and that the code words are also firmly integrated into the Pula frame of the DSV2 are.

The invention is based on the object of providing at least one digital Slultiplex signal DS1 with a bit rate of 992 kbit that is a high quality digitized one and error-protected stereo audio signal with a bit rate of 960 kbit / s, a dem Additional information of 20 kbit / s associated with the stereo audio signal and a frame identifier with a bit rate of 12 kbit / s contains a DSV2 to transmit that also plesiochronous operation is possible and that either two alternatively via a DSV2 such digital multiplex signals DS1 and DS1 'or in addition to the transmission only one such N-tilti- plexsignals DS1 14 time channels unrestricted can be occupied with telephone channels.

The object is achieved by the invention characterized in the main claim solved.

The subclaims relate to advantageous developments of the invention.

A major advantage of the invention is over a 2 Mbit / s digital signal connection (DSV2, formerly PCM30) up to two digital multiplex signals DS1, independent of the bit sequence, DS1 'with a bit rate of 992 kbit / s each to be able to transmit, each of which is a high quality digitized stereo audio signal, error-protected in every sample, with the associated Contain additional information and frame identifier words. Thus stand as transmission systems all systems of the PCM hierarchy are available.

Bit sequence-independent means that the multiplex signals through their own Frame identifier words are not linked to the pulse frame of the DSV2.

The operation of a pesiochronous network is made possible by the timing adjustment method made possible according to the invention. When transitioning from a plesiochronous network to a synchronous network, no changes in the device technology are required. Advantageous is furthermore that runtime differences and runtime crawls in a synchronous Network can be compensated by this clock adjustment process and thus on the use of special delay equalizers can be dispensed with. Another advantage of the invention consists in that with the help of a digital signal insertion device any not fully occupied DSV2 for the transmission of a high quality digitized stereo audio signal with additional information can be used as DS1, if at least 16 free remote talk channels available.

The invention is explained in more detail with reference to FIGS.

Fig. 1 shows the known pulse frame structure of a DSV2, Fig. 2 shows the assignment of a Pula frame when transmitting two digital multiplex signals DS1 and DS1 'Fig. 3 shows the occupancy of a Pula frame during the transmission of a Multiplex signals DS1 and 14 telephone channels and Fig. 4 shows a table for Coding of the timing adjustment information.

In Fig. 1, two successive pulse frames PR are known Structure of a DSV2 shown below each other. Each pulse frame FR consists of 32 time channels O to 31 of 8 bit length each and begins alternating from pulse frame to pulse frame either with a sync word S or a message word M. 15 telephone channels follow Fl to F15, a license plate channel K and a further 15 telephone channels F16 to F30.

A total of 16 pulse frames PR form a superframe of the DSV2.

In Fig. 2, a pulse frame is shown with a first digital Multiplex signal DS1 (shown hatched) and a second digital multiplex signal DS1 '(these are the unlabeled fields of the even-numbered time channels in FIG. 2 and the 2-bit remainder of the time channels 1 and 31) according to the invention is. In this case, too, the pulse frames begin alternately with a sync word S or a message word M in time channel 0.

The first multiplex signal DS1 occupies the odd-numbered time channels 1, 3, ... 31, whereby it only occupies 6 bits in time channel 1 and in time channel 31. The second multiplex signal DS1 'occupies the even-numbered time channels 2, 4, ... 30 and additionally the remaining 2 bits of time channel 1 and time channel 31.

Fig. 3 shows the structure of a pulse frame of the DSV2 in the mixed Allocation with a digital multiplex signal DS1 and 14 telephone channels F2, F4, .. F14, F17, F19, ... F29 and the switching technology code in the code channel K of time channel 16.

Here, too, the multiplex signal DS1 is shown hatched. the in each of the time channels 1 and 31, the 2 bits that remain free and those that become free for each superframe 8 x 8 bits from the license plate channel (every second word in the license plate channel is free) result in a transmission capacity of the bit rate of 64 kbit / s, which is necessary for the transmission any information can be used.

In order to achieve the necessary clock adjustment of the multiplex signals in the case of piesiochronous To carry out the operation of the transmission systems, two superframes of the DSV2 become summarized in a clock adjustment superframe and each one for free assignment available bit in the message words M is used as clock adjustment bit T.

As a result of this measure, there are 32 pulse frames per clock adaptation superframe PR with a total of 16 message words M, i.e. also 16 clock adjustment bits T are available, to transmit the clock adjustment information for both multiplex signals DS1 and DS1 '.

After subtracting four clock adjustment bits T for the synchronization of the Clock adjustment superframes remain when the DSV2 is assigned the two multiplex signals DS1 and DS1 'each have 6 clock adjustment bits T for signaling the type of clock adjustment. The positive-zero-negative clock adjustment method is preferably used. The four possible types of clock adjustment are, as the table in FIG. 4 shows, with two clock adjustment bits T are transmitted in coded form. A high level of security against errors is achieved in that the same clock adjustment information is provided for each act adjustment superframe each transferred three times and by majority decision evaluated will.

If only one nultiplex signal DS1 is transmitted, the free clock adjustment bits T either with dummy information or with any information proven.

It is useful as an agreed place to insert an empty bit with positive clock adjustment or to hide a LOW or HIGH bit with negative Clock adjustment the first bit Each multiplex signal DS1, DS1 'in the clock adjustment superframe, so the first bit of the time channel 3 for the first multiplex signal DS1 and the first bit of time channel 2 for the second multiplex signal DS1 'in the zeroth pulse frame of the clock adjustment superframe to be provided.

This type of clock adjustment makes it possible to avoid clock deviations compensate up to a magnitude of 10 4.

In the event of a positive clock adjustment, an agreed point within of the clock adjustment superframe, an empty bit is inserted into the multiplex signal DS1 or DS1 ' and removed again after the transfer via the DSV2.

For negative clock adjustment, we adjust to this agreed setting bit removed from the multiplex signal DS1 or DS1 ', transmitted encoded in the message word reinserted into the multiplex signal after transmission.

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Claims (9)

Multiplex process for the digital transmission of stereophonic sound signals on devices of the standardized PCM hierarchy (9) patent claims 0 method for Transmission of at least one digital multiplex signal (DS1) with a bit rate of 992 kbit / s, which is a high-quality digitized and error-proof stereo audio signal with associated additional information as well as its own frame code words contains about a 2 Mbit / s digital signal connection (DSV2, formerly PCM30), whose pulse frame (PR) is made up of 32 time channels (0 to 31) of 8 bits each and with 30 telephone channels (F1 to F30), a code channel (E) and alternately per pulse frame (PR) in the zeroth time channel (0) either with a sync word (S) or with a message word (M) is occupied and in each case 16 pulse frames (PR) form a superframe, i a d u r c h g e k e n n z e i c h n e t - that a first multiplex signal (1) si) the 16 odd-numbered time channels (1, 3, .... 31) occupied, whereby it is in two time channels (1 and 31) only occupy 6 bits each, - that a second multiplex signal (DS1 ') the 15 Odd-numbered time channels (2, 4, ... 30) fully occupied and in those of the first multiplex signal (dz1) two time channels (1 and 31) only partially occupied the remaining ones 2 bits occupied and - that the type of clock adjustment is transmitted in the zeroth time channel (0) wirQ (Fig. 2). 2 transmission method according to claim 1, characterized in that that instead of the second multiplex signal (DS1 ') 14 intercom channels (F2, F4, ... F14, F17, F19, ... F29) and the associated license plate channel (x) in the even-numbered Time channels (2, 4, ... 30) are transmitted (Fig. 3). 3 transmission method according to claim 2, characterized in that that in every second pulse frame (PR) unoccupied identifier channels (K) and those released in every first and thirty-first time channel (1 and 31) 2 bit can be assigned any information. 4 transmission method according to claim 1 or 2, characterized in that that in each message word (M) a bit provided for free assignment as a clock adjustment bit (2) is used. 5 transmission method according to claim 4, characterized in that two superframes each with a total of 16 message words (M) and a total of 16 clock adjustment bits (T) are combined to form a clock adjustment superframe. 6 transmission method according to claim 5, characterized in that four clock adjustment bits (b) per clock adjustment superframe of the synchronization of the act adaptation superframes serve. 7 transmission method according to claim 5, characterized in that Two further clock adjustment bits (T) each one of the four possible clock adjustment information: a) no clock adjustment, b) positive clock adjustment - one empty bit of the agreed Place inserted -, c) negative clock matching - a LOW bit at the agreed point removed - and d) negative clock adjustment - a HIGH bit at the agreed point signal removed (Fig. 4). 8 transmission method according to claim 7, characterized in that three times the same clock adjustment information for each multiplex signal (dz1, DS1 ') is transmitted within a clock adjustment superframe. 9 transmission method according to claim 7, characterized in that that as an agreed place to insert an empty bit or to hide a LOW or HIGH bits The first bit of the third time channel (3) for the first Multiplex signal (DS1) and the first bit of the second time channel (2) for the second Multiplex signal (DS1 ') in the zeroth pulse frame Each clock adjustment superframe applies.