CA2084791A1

CA2084791A1 - Process for transmitting a time-variable control parameter

Info

Publication number: CA2084791A1
Application number: CA 2084791
Authority: CA
Inventors: Juergen Mielke; Georg Plenge
Original assignee: Individual
Current assignee: Deutsche Thomson OHG
Priority date: 1990-06-30
Filing date: 1991-06-26
Publication date: 1991-12-31
Also published as: CZ369792A3; HU9203809D0; DE4020932A1; WO1992000637A1; AU8005991A; CZ279940B6; JPH05508758A; EP0538289A1; DE4020932C2; HUT63018A; AU655588B2

Abstract

Abstract For individual tuning of the dynamics of a radio programme signal (variable dynamics), a control parameter is derived from the associated radio programme signal and emitted together with the programme signal. At the receiver, the control signal is used to select reproduction dynamics differing from the transmitted programme-signal dynamics. For transmission purposes. the control parameter is inserted as a digital auxiliary signal in a data stream which is transmitted asynchronously to the programme signal in a programme-signal-free region Or the transmission band. The digital auxiliary signal is inserted at intervals as a data packet with varying advance with respect to the programme-signal section concerned. The variable time differences between the points in time at which the data packets are inserted and the occurence of the programme signal sections are transmitted as sepa-rated lime information in the data packets and used at the receiver to synchronize the advanced control signal with the pro-gramme signal.

Description

2as~7~l Process for Transmitting a Time-variable Control Parameter D E S C R I P T I O N

The invention relates to a process (method) according to the preamble of patent claim 1. Such a process is known from the "EBU Review-Technical", No. 218 (August 1986), pages 2 through 12.

Radio broadcast audio signals are fed to the transmitters with a dynamic (difference between the loudest and quietest signals) which is adapted to the signal-to-noise ratio of the subse~uent transmission path. However, the dynamics resulting from this in many cases does not correspond to the individual wishes of the radio listen~r~
Therefore, for example, when listening in a vehicle while it is moving, the transmitted dynamic is m~ch too large owing to ~he noise level in the vehicle, whereas, for example, when listening via headphones, the transmitted dynamics, normally lower then the original dynamics of the recorded acoustic sîgnal, is too low.

In order to markedly improve the reproduction of the audio signal, it is desirable to be able to adapt the dynamics individually at the place of reproduction to the wishes of the listener. For this, it is known ("EBU Review-Technical", No. 218, August 1986) to derive a control parameter (manipulated variable) from the program signal REPI ACEMENT SHEET

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2as~7~l WO 92/00637 ~ 2 - PCT/EP91/01202 which then represents the restriction of the original dynamics to a so-called ~target dynamic". ~Target dynamic"
is understood to be the restriction to a certain value, for example, 30 dB, which is less than the transmitted dynamics.
This control signal is transmitted sychronized with the associated program signal and evaluated in the receiver for the variable dynamics selection. The free choice of dynamic is rendered possible in that the "target dynamic" is realized with the aid of the transmitted control parameter or is further constricted (vehicle) or the original dynamics is recreated through inverse utilization of the control signal.

For transmitting the "variable dynamics" control signal it is known (DE-PS 33 11 646 and DE-PS 33 11 647) to insert, inaudibly, a fixed and a variable audio frequency with low level at the lower frequency end of the S signal of an M/S-coded stereophonic audio signal, whereby the frequency separation of said frequencies represents the current control parameter. However, the narrow-band filters necessary for the demodulation of the frequency separation do not allow rapid alterations to the control parameter;
further, the frequency range in the S signal provided for the transmission of the control parameter is not sufficiently interference-free in order to guarantee a reliable transmission with the small signal levels used for the audio frequencies. In particular, interference in the frequency range concerned occurs through multipath reception in the case of mobile reception.

Owing to these serious defects, a digital transmission of the "variable dynamics" control signal is desirable in a region of the transmission band of the broadcast signal which is free from program signals. For the case of a television sound signal, for e~ample, the blanking region of the picture signal, already irl use for other digital REPLACEMENT SHEET

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- 3 - PCT/EP91/0120 auxiliary signals [videotext), could be considered as the region free from program signals. An auxiliary carrier in the multiplex channel offers itself ~or an FM signal;
howaver, there is the dif~iculty here that already the identification signals for traffic program broadcasts as well as the data stream for Radio Data System (RDS) are transmitted at 57 kHz, and other auxiliary carriers are not acceptable to the radio broadcast subscriber owing to the expanditure relating to the decoder on the receiver side.
However, inserting the "variable dynamics" control signal into the RDS data stream or the videotext data stream respectively is is not possible because these data streams are not broadcast sychroni~ed with the FM audio or television sound signals respectively, something which runs counter to the requirement for a synchronized transmission of the "variable dynamicsl' control signal.

The object of the invention consists of creating a process for transmitting the "variable dynamics" control signal which, despite non-synchronized data stream transmission, guarantees the necessary synchronization between the control variabl~ and the program signal on the receiver side.

This task is solved according to the invention by the charactexizing features of patent claim 1.

Embodiments and further developments of the process according to the invention ensue from the subclaims.

~ he process according to the invention is based on the consideration that ~he ~variable dynamics~ control signal is not isochronous with the program signal but, on the contrary, leaves the broadcasting studio with a constant advance of, for example, 1000 ms. This advance permits the following method of functioning, explained by means of an RDS data stream.

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- 4 - PCT/EP91/01202 The ~DS coder at the transmitter receives the control signal and stores it. AS soon as the RDS coder has a free group (sequence of data bits) available, the digitalized control signal is transmitted as a data packet in this group. The 37 net bits available in one group could be used as follows:

32 bits ~or the transmission of the "variable dynamics~' control parametex

5 bits for the identification of the time of transmission.

The latter 5 bits specify by how many milliseconds the transmission has been delayed in the ~DS coder or, respectively, how much of the advance time has been "consumed". This information allows the receiver to:

- temporally deaccentuate the data packet again and convert it into individual discrete control signals with constant temporal separation so that a constant control data stream rasults at the end, and - further delay ~hese data in a simple shift register in such a way that the entire advance time is compensated, and the constant control data stream is again available, synchronized with the program signal.

The invention will be explained in more detail by means of embodiment examples illustrated in the drawings. They show in:

Fig. 1 a block circuit diagram of an installation on the transmitter side for executing the process according to the invention;

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' ' ,' '' ' ' ' ' 2~7~1 wo 92/00637 - 5 - Pc~/Ep9l/ol2o2 Fig. 2 a block circuit diagram of an in~allation on the receiver side for executing the process according to th~ invention;

Fig. 3 a block circuit diagram of an installation, modified compared to Fig~ 2, for executing a variation of the process according to the invention, and igs. 4a through 4g diagrams for illustrating individual steps of the process according to the invention.

The installation for executing the process according to the invention on the transmitter side, illustrated schematically by means of Fig. 1, shows a radio broadcast studio 10 in which a radio broadcast program signal 11 and a "Variable Dyna~ics" control signal 12 are generated. The control signal 12 is here derived from the program signal, as already explained above. The essential factor is that at, or respectively, prior to the output from the studio 10, a temporal delay of the program signal 11 with respect ~o the control signal 12 is carried out, indicated in Fig. 1 by a time function e]ement 13 with a constant delay time. This delay leads to the con~rol signal 12 being in advance of the associated program sec~ion of the program signal llo In Fig. 4a, three program sections n, n+1 and n+2, each having the same te~poral length, are plotted for an assumed time sequence of a radio broadcast program signal. The ~Variable Dynamics" contrcl signal is d~rived, for example, in the form of discr~te scanning values, ~rom each program section n or n+1 respectively. The scanning values for each program signal segment are, as Fig. 4c shows/ combined in a digital form into a data packet, whereby, at the time of the final scanning value, the associated data packet begins in the example presented.

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- 6 - PCTtEP91/01202 As also follows from Fig. 1, the program signal 11 and the control signal 12 are transmitted to th~ transmitter location 16 via separate lines 14 and 15 respectively. The transmitter location 16 comprises, in the example presented, an FM transmitter 17 as well as an RDS coder 18, whereby the program signal 11 is sent to the transmitter 17 and the advanced control signal 12 is sent to the RDS coder 18. The RDS coder 18 inserts the data packets of the control signal 12, dela~ed by a variable time ~(deltaJ T, into its RDS data stream, as is to be explained in more detail in the following by means of Figs. 4d and 4e or 4f and 4g respectively.

With the variation according to Fig. 4d, the data stream stored in the ~DS coder 18 contains a cyclic sequence of groups in which groups VD for inserting the "Variable Dynamics~ control signal are already provided. The cycle illustrated in Fig. 4d comprises the groups OA, VD, 2A, OA, VD, 6A, OA, VD, 6~, 2A, OA, VD, 6A and 6A~ The insertion of the data packets of the control signal allocated to the program segments n, n+1 and n+2 is shown in Fig. 4e. In this case some of the groups VD in the transmitted RDS data stream reserved for the insertion of the control signal are omitted if no data packets are present to be inserted for these groups. This means, in the case o~ the example according to Fig. 4d, that the groups VD with the current group numbers 2 and 5 are not transmitted so that at the time of the appearance of the data packet under consideration for the current number n~ the data packets 1, 3, 4 and 6 have already been broadcast or, respectively, (data packet No. 6) are just being broadcast. The next free qroup VD is, therefore, group No. 8 so that the insertion of data packet n must wait until group No. 7 has been broadcast completely. This waiting time is designated ~tn in Fig. 4e.
The same considerations apply to the data packets with the current numbers n~l and n~2, whereby in this case the REPLACEMENT SE~EET

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wO 92~00637 - 7 - PCT/EP91/01202 waiting times ares designated ~tn+1 and ~tn+2 respectively.
As one can see by means of the waiting times plotted, the waiting times are different owing to the structure of the stored RDS data stream and can have, as a maxLmum, the separation between two successive groups VD. As a result of the respective waiting time ~t, the advance of the control signal 12 is reduced, with respect to the associated program signal segment, to the value ~ftau) -~t. As the program signal and the control signal need to be synchronized in the receiver, the waiting times ~t are recorded in the RDS coder 18 and transmitted in coded form in the data packet concerned.

The transmitted RDS data s~ream is fed from the RDS
coder 18 to the transmitter 17 where it is transmitted on an auxiliary carrier in the multiplex region of the program signal according to the standard.

As an alternative to providing groups VD in the stored sequence of RDS groups, it is also possible, according to Fig. 4f, to do without such a provision, as is quire clear from comparing Figs. 4d and 4f. One advantage of this is that the sequence of groups (cycle) stored in the RDS coder 18 is considerably shorter than is the case in Fiq. 4d. If a data packet is to be insert~d into the stored sequence of RDS groups according ~o Fig. 4f, then this insertion is performed at the end of the group just sent, whereby the next group in the cycle is displaced by the duration of one yroup. As Fig. 4g shows, the insertion of the data packet n is carried out at the end of the group with the current number 4 in the cycle 1, data packet n~l at the end of the group with the current number 7 in the cycle 2 and data packet n+2 at the end of the group with the current number 9 in the cycle 2. Likewise, from this there result waiting times of ~tn, Atn+l and ~tn+2 respectively which, however, are considerably shor~er when compared to the waiting times REPLACEMEN~ SEIEET

2~847~1 W0 92/00637 ~ 8 - PCT/~P91/01202 according to Fig. 4e. This represents another advantage of the alternative according to Figs. 4f and 4g.

Using the installation on the receiver side illustrated schematically by means of Fig. 2, the broadcast RDS data stream is separated from the radio broadcast program signal in the RDS-compatible receiver and fed to an RDS decoder 21 which demodulates and decodes the carried RDS data stream.
The decoded RDS data stream is passed on to the stage 22 (which may also form part of the decoder 21) where the separation and evaluation of the ~Variable Dynamics" control signal is carried out. When doing this, the information on the waiting time ~t contained in each data packet is also retrieved and this serves for controlling a subsequent buffer memory 23 for the ~Variable Dynamics~ control signal.
The control signal appearing at the output of the buffer memory 23 is once again synchronized with the associated signal segment of the program signal which is fed from the receiver 20 to a controlled amplifier 24. The control signal occuring simultaneously at the control input of the regulated amplifier 24 changes the amplification of the program signal according to a manual input 25 for the amplifier 24 so that the program signal reproduced via loudspeaker 26 or non-illustrated headphones respectively exhibits a dynamic corresponding to the individual wishes of the listener or the manual specification at input 25 respectively. Hence, the execution of the procedure steps according to Figs. 4a through 4g are carried out on the receiver side in the reverse order to that of the transmitter side.

A further embodiment example on the receiver side, based on the idea that only a limited capacity is available in an RDS transmission channel for transmitting the ~Variable Dynamics" control signal, is illustrated in Fig. 3.
Nevertheless, in order to guarantee, in particular, a data-REPLACEMENT SEIEET

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, 2~7~1 wo 92/00637 - 9 - PCT/EP91/01202 protected transmission in the RDS channel, typical control signal progressions (forms) are permanently stored in a memory 27 on the receiver side which is provided instead of the buffer memory 23 according to Fig. 2. Merely the addresses of the respective desired control signal progressions are transmitted as the contents of the data packets of the "Variable Dynamics" control signal, thereby takiny up considerably less channel capacity than the transmission of the control signal progressions as such. In addition to the addresses of the permanently stored control signal progressions, the control signal values actually occuring on the boundaries of the program signal segments and used in the memory 27 for the plausibility check and/or correction and/or for initialization upon switching on the device, changing program ox when the control signal is unavailable can be transmitted. The saving in capacity achieved with the help of this alternative technique is so large that each data packet can be transmitted twice in the RDS data stream, meaning a considerable increase in the transmission relia~ility.

A table with examples of typical control signal progressions is plotted ~elow the circuit block 27 in Fig.
3; the following can be seen:
a straight line with a gradient of 0 (constant dynamic~

a straight line with a positive gradient (climbing dynamic) a straight line with a negative gradient lfalling dynamic) signal leaps with various amplitudes, various directions and occuring at various times (jump-type dynamic alterations according to size, direction and time).

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Claims

PATENT CLAIMS

1. Process for transmitting a time-variable control parameter which is derived from an associated radio broadcast program signal and is broadcast together with the program signal in order to be used, on the receiver side, for the selection of a reproduction dynamic deviating from the transmitted program signal dynamic, in which the control parameter, as a digital auxiliary signal, is inserted at intervals into a data stream as a data packet which is transmitted in a program signal-free region of the transmission band of the radio broadcast program signal and non-synchronized with such, c h a r a c t e r i z e d i n t h a t the insertion of the digital auxiliary signal is carried out with a varying advance with respect to the corresponding program signal segment of the program signal, and that the variable time differences between the times of the intervallic insertion of the data packets and the appearance of the program signal segments concerned is transmitted as seperate time information in the data packets and used, on the receiver side, for synchronizing the advance control signal with the program signal.

(c) the variable time differences between the times of the intervallic insertion of the data packets and the appearance of the program signal segments concerned transmitted as seperate time information in the data packets and used, on the receiver side, for synchronizing the advance control signal with the program signal.

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2. Process according to claim 1, c h a r a c t e r -i z e d i n t h a t a multiplicity of typical control signal progressions are permanently stored on the receiver side, and that merely the addresses of the permanently stored control signal progressions are transmitted as control signals.

3. Process according to claim 2, c h a r a c t e r -i z e d i n t h a t in addition, together with the addresses of the permanently stored control signal progressions, the control signal values actually occuring on the boundaries of the program signal segments are transmitted which are used on the receiver side for the plausibility check and/or correction and/or for initialization upon switching on the device, changing program or when the control signal is unavailable.

4. Process according to one of the claims 1 through 3, c h a r a c t e r i z e d i n t h a t the digital auxiliary signal is inserted into the data stream of a Radio Data Signal (RDS signal) which is transmitted on a auxiliary carrier in the multiplex channel of an FM
radio broadcast program signal.

5. Process according to claim 4, c h a r a c t e r -i z e d i n t h a t periodically repeated sequences of data bits (groups) are provided in the RDS data stream for the transmission of the control signal, and that a larger number of groups is provided in the RDS
data stream than is necessary, and that only such groups are broadcast as are occupied with a data packet of the digital auxiliary signal.

6. Process according to claim 4, c h a r a c t e r -i z e d i n t h a t sequences of data bits (groups) REPLACEMENT SHEET

are inserted into the RDS data stream between other groups each for receiving (holding) one data packet of the digital auxiliary signal as required.

7. Process according to one of the claims 1 through 6, c h a r a c t e r i z e d i n t h a t the digital auxiliary signal is separated from the data stream and evaluated on the receiver side.

8. Process according to claim 7, c h a r a c t e r -i z e d i n t h a t the information contained in each data packet concerning the waiting time .DELTA.t (Delta t) is retrieved upon evaluation and this serves for controlling a memory (23) for the "Variable Dynamics"
control signal.

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