CZ20011291A3 - Transmission of digital information signal with M bit PCM samples - Google Patents

Abstract

A transmitter is disclosed for transmitting a digital information signal having M bit PCM samples via a transmission medium. The M bit PCM signal is split (8) into a P bit PCM signal, whereby P < M and a difference signal. The P bit PCM signal is a lower quality representation of the M bit PCM digital information signal and the difference signal is obtained by subtracting the P bit PCM signal from the M bit PCM signal. The difference signal is data compressed (16) so as to obtain a data compressed difference signal. The P bit PCM signal and the data compressed difference signal are combined (24) so as to obtain a transmission signal. The transmission signal is transmitted via the transmission medium (TRM).

Description

Technical field

The present invention relates to a transmitter for transmitting a digital information signal with M bit PCM samples, a receiver for receiving a broadcast signal carrying a digital information signal from a transmission medium, and for generating a Q bit PCM signal that represents said digital information signal, from said broadcast signal, a record carrier, which is formed by the transmitter when it is in the form of an apparatus for recording information on the record carrier, and a method of transmission.

BACKGROUND OF THE INVENTION

Transmitters and receivers as defined above are known, for example, from USP 5,479,168. Said document discloses a method of signal coding, transmission and decoding in order to achieve improved reproduction of a digital information signal with M bit samples, said method of decoding, compatible with an industrial receiver which, while maintaining normalized signal receivers not containing the decoding properties of the present invention . The transmitter analyzes and encodes the digital information signal to obtain a modified version of the digital information signal and control codes for transmission by transmission.

information operations and operations that are performed to encode the digital information signal. The control codes are used to control the operation of decoding and reconstructing the properties of the digital information signal.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a transmitter and receiver having another and less complicated method of transmitting and receiving a digital information signal with M bit PCM samples, while maintaining the compatibility of the transmitted signal with industry standardized signal playback devices in which the reception method is not built. according to the present invention, said digital information signal has a higher quality than the signal that is reproduced by said industrially standardized playback devices.

Detailed description

The transmitter of the present invention comprises

input means for receiving an M bit PCM signal

- means for dividing the M bit PCM signal into a representation of the digital information signal by the P bit PCM samples and the difference signal which is the difference between the M bit PCM signal and the P bit PCM signal, where Μ> P

- first means for combining the P bit PCM signal and the difference signal in order to obtain a transmission signal for * * ♦ β · ··· · · · φ <· φ · φφφ · · φ φ · Φ · ΦΦΦΦ φ · φ * ΦΦΦΦ ♦ · Φ φ · φ φ φ φ φ φ přenos φ přenos přenosφ přenos

The receiver according to the invention comprises

means for obtaining a broadcast signal from the broadcast medium

- demultiplexing means for deriving a P bit PCM representation of the digital information signal and the difference signal from the broadcast signal

means for coupling the signal, for coupling the P bit PCM signal and the difference signal to obtain a Q bit PCM signal, wherein Q > P.

The present invention is based on the following disclosure. The transmitter of the present invention divides the digital information signal with M bit PCM samples into a digital information signal representation that is composed of P bit PCM samples and a difference signal. Representations of the digital information signal and the difference signal are combined to obtain a broadcast signal to be transmitted. The transmission signal is transmitted by the transmission medium.

In a preferred embodiment of the transmitter, the first signal coupling means is adapted to obtain a transmission signal comprising an N bit PCM signal that is a version of the P bit PCM signal, where N> P. An advantage of said embodiment is that the broadcast signal thus obtained can be received and processed by receivers of prior design, which can receive and process and transmit an N bit PCM signal.

The data capacity required for transmitting a differential signal is generally very small. Even data compression can be performed on the difference signal to further reduce the necessary data capacity. The transmitter is therefore equipped with data compression means in order to reduce the required data. F 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0 0 0 000 000 _Mt data capacity for transmitting a differential signal. Preferably, the data compression means comprise a psychoacoustic encoder that removes irrelevancy and redundancy in the differential signal.

Dividing may be performed by dividing the M bit PCM samples of the digital information signal into P most significant bits to obtain a P bit PCM signal and an M-P least significant bits to obtain a difference signal. In this case, P < N, P-N of least significant bits can be used to store at least a portion of the difference signal that can be data compressed.

A nested channel method may also be used to create a nested data channel in a P bit PCM signal for transmitting at least a portion of the difference signal. Using the nested data method, the perceived signal-to-noise ratio of the transmitted N-bit PCM signal is approximately equal to the signal-to-noise ratio of the P-bit PCM signal.

The receivers of the present invention can restore both transmitted signal components to re-create M bit PCM digital information signal replicas.

Overview of the drawings

These and other objects of the present invention will be apparent and explained in more detail below with reference to embodiments described in the following description of the figures, wherein FIG. 1 shows a first embodiment of a transmitter; FIG. 2 shows a first embodiment of a receiver; ···. "♦ • · · · · · · · · ·· • * ·" ··· "· 9 •••••« • ···· ··· I »· ·· * Figures _βββ Fig. 3 shows an earlier receiver for receiving the transmitted signal generated by the transmitter of Fig. 1; Fig. 4 shows a first embodiment of the splitting means in the transmitter; Fig. 5 shows a third embodiment of the signal coupling unit in the transmitter of Fig. 1. Fig. 2 shows a fourth embodiment of a demultiplexer unit in the receiver of Fig. 2; Fig. 7 shows a fourth embodiment of a signal coupler unit in the transmitter of Fig. 1; and FIG. 2 FIG. 9 shows a transmitter in the form of a recording apparatus Fig. 10 shows the receiver in the form of reproducing apparatus Fig. 11 shows another embodiment of the transmitter in the form of a recording apparatus Fig. 12 shows another embodiment of a receiver in the form of reproductive apparatus

DETAILED DESCRIPTION OF THE INVENTION

Giant. 1 shows one embodiment of a transmitter. The transmitter has an input terminal 1 for receiving a digital information signal, such as a digital audio signal, which includes M bit PCM samples. This digital information signal can be obtained by applying an analogue form of digital information signal to the input of the 2 A / D converter • · ··· * ·· «• · · Φ ·· ·

4 · 44 44 • 44 φ φ 44 44 β 44 _,,,,,,,

4. The A / D converter 4 samples the signal that is applied to its input 2 and supplies digitized M bit patterns at the input terminal 1 of the transmitter. The input terminal 1 is connected to the input 6 of the subdivision unit JB. The splitting unit 8 is adapted to divide the M bit PCM signal that is input to its P bit PCM signal, which is a representation of a digital information signal with M bit PCM samples, where Μ> P, and the difference signal that was obtained by subtracting The P bit PCM signal from the M bit PCM signal that was applied to its input 6. The P bit PCM signal and the difference signal are applied to the first output 10, respectively. on the second output 12 of the division unit 8.

As an example, M can be selected equal to 24 and P equal to 16 so that the representation can be stored in the form of an industrially standardized signal, eg on a standard CD.

The output 12 of the splitting unit 8 is connected to the first input 14 of the data compression unit 16. The data compression unit is optional and is not critical to the present invention. The data compression unit compresses the difference signal that is received by its first input to obtain a data compressed difference signal that is output to its output

18.

The output 10 of the splitting unit 8 22 of the data compression signal coupling unit 16 is coupled to and coupled to the first input

24. Output 18 of the unit by second input 26 of signal splicing unit 24. The signal splicing unit 24 couples the signals applied to its inputs 22 and 26 into at least one serial data stream suitable for transmission by the transmission medium TRM. The signal coupling step in the signal coupling unit 24 may further comprise an encoding step 1

· • «| |« | | | «« «| | | |« «« | « a channel that is well known.

The data compression unit 16 may include a standard arithmetic encoder, such as a Huffman encoder, which is well known. The splitting unit 8 performs a quantization step to obtain a P bit PCM signal. The quantization noise in the P bit PCM signal causes the noise of the difference signal. That is why the difference signal spectrum is very similar to white noise. To improve data compression, the unit 16 may include a psychoacoustic model that is well known. The data compression unit 16 therefore comprises a second input 20 which is connected to the input terminal 1 to receive an M bit digital information signal. The enhancement can be used to increase the data capacity that can be used to transmit a differential signal or to increase the perceived signal-to-noise ratio that can be obtained by a receiver having the features of the present invention.

The transmitter described above operates as follows. The digital information signal is applied to the input terminal

1. The splitting unit splits the digital information signal with M bit PCM samples into a P bit PCM signal, which is a representation of a low quality digital information signal, and a difference signal. The difference signal includes signal information from the M bit PCM signal required on the receiver side to reproduce a high quality representation of the digital information signal in the form of an M bit PCM signal by combining the P bit PCM signal and the difference signal. The P bit PCM signal and the difference signal, if such data is compressed, are combined to obtain a transmission signal for transmission by the transmission medium TRM. The transmission signal carries a P bit PCM signal such that the 4 bit signal is such that a receiver in which the features of the present invention are not incorporated may reproduce said signal.

A TRM transmission medium such as a recording medium. The transmission signal is to the receiver.

In Fig. 2, a broadcast channel or magnetic or optical carrier may be transmitted on a TRM transmission medium of a receiver for receiving a broadcast signal from which it reconstitutes and reproduces the original digital information signal.

The transmission signal is received by the input 60 of the demultiplexing unit 62. The demultiplexing unit 62 can recover the P bit

A PCM signal from the broadcast signal and conducts said signal to the first input 68 of the signal coupling unit 70.

The other input 66 of the demultiplexing unit 62 is coupled to the input 72 of the data expansion unit 74. The demultiplexing unit 62 is able to recover the difference signal from the broadcast signal and output the recovered signal to output 66, which is coupled to the second input 76 of the splicing unit 70. signal splicing 70 couples the signals received by its first and second inputs to obtain a Q bit PCM replica of the original digital information signal. The output 78 of the signal splicing unit 70 is coupled to the receiver output 80 when required via the D / A converter 82. The receiver may additionally include a second D / A converter, not shown, whose input is coupled to the output 64 of the demultiplexer 62 and the output. it is connected to another output terminal (not shown).

The function of the receiver of Fig. 2 is as follows. The demultiplexer 62 restores a P bit PCM signal that is φ · · · · ·

φ * ♦ φ φφφφ φφφ φ φ · ·· ae, information signal representing digital φ transmitted

φ · φφφ of low quality and conducts said signal to output 64.

The demultiplexing unit 62 can also, if so compressed data, recover the difference signal, and output said signal to output 66. If necessary, the data expansion unit 74 restores the data compressed difference signal at the input 72, expanding the signal to obtain a differential the difference signal relates to digital information signal signals below a certain level that are not present in the P bit PCM signal that represents the M bit PCM digital information signal and the quantization noise that it is introduced by the division unit in the transmitter. The data expansion unit 84 may include a psychoacoustic decoder that is a lossy decoder or an entropy decoder that is a lossless decoder, such as a Huffman decoder. These decoders are well known. The signal splicing unit 70 couples the P bit PCM signal and the difference signal to obtain a Q bit PCM signal that is a replica of the original digital information signal and outputs the Q bit PCM signal to its output 78. The Q value depends on the data expansion unit 84. is used. Depending on the complexity of the data expansion unit 84, the data expansion unit may reconstruct a higher quality signal. Value Q Q bitwise

The PCM signal that is generated by the signal splicing unit is coupled to the quality of the reconstructed difference signal that is received at input 76. To produce a reproduction signal of higher quality than the P bit PCM signal, it is deaf to at least increase the Q value. The D / A converter 82, which can be used, converts a replica of the digital information signal to an analog signal.

FIG. 4 shows an embodiment of the transmitter splitter unit of FIG. 1. The splitter unit input 6 receives a digital information signal with M bit PCM samples. Quantizer 4.2 performs quantization of the M bit PCM signal to obtain a P bit PCM signal that represents the digital information signal, and outputs the P bit PCM signal to the output 10 of the division unit 8. The quantization step performed may be performed by rounding or trimming only. the quantization method may also be appropriate, including noise shaping or ditering. The splitting unit further comprises a subtraction unit 4.4 which subtracts the P bit PCM signal from the M bit PCM signal to obtain a difference signal. The difference signal is output to the splitter unit 8. The splitter unit may also be adapted to perform the trimming function by supplying the P most significant bits from the M bit PCM samples to output 10 and supplying the MP of the least significant bits to output 12.

The transmitter is preferably compatible with industrially standardized devices even on eg CD players. Therefore, the modified N bit should preferably be for generation

PCM signal.

N equals 16.

P bit PCM signal, where P <N.

a signal, such as splicing a signal 24 of a signal that is with a CD standard, the division 8 reproduction 'is a transmission unit

For compatibility

Therefore, it creates a unit

The former receiver shown in Fig. 3 includes a demultiplexer unit 62 that is capable of recovering an N-bit PCM signal that is a representation of a P-bit representation of a N-bit digital information signal. 9 4 · 14 4 14 14 4 944 44 4 4

4444 4 · 4 9 · · · 4 · «« * ₉ samples, from a transmission signal that is transmitted by the TRM transmission medium. The receiver includes a D / A converter 82. to bring the analog version of the digital information signal representation to output 84. In an earlier receiver, a D / A converter with a smaller dynamic range is sufficient, there is N <M.

A first embodiment of the signal splicing unit 24 may be used if Ρ <N. The signal splicing unit receives a P bit PCM signal at the first input 22. The P bit PCM signal samples are used to generate the P most significant sample bits from the N bit PCM signal in the transmission. signal. The NPs of the least significant bits in the N bit PCM signal are used to transmit at least a portion of the difference signal, if so compressed, received at the second input 26 of the signal splicing unit 24. The previous receiver reproduces the N bit PCM signal which contains the P bit PCM signal. is a replica of lower quality digital information signal.

The N-P of the least significant bits in the N bit PCM signal will be reproduced as little signal noise that is added to the P bit PCM signal. When the N bit PCM signal has a small amplitude, said low signal noise may be audible.

The first embodiment of the demultiplexing unit 62 in the receiver of Fig. 2 is adapted to receive a broadcast signal with an N bit PCM signal. The demultiplexer selects the P most significant bits from the N bit PCM signal to obtain the P bit PCM signal at the output 64. Further, the demultiplexer selects the NP of the least significant bits from the N bit PCM signal to obtain the difference signal when the data is compressed so exit 66.

In the following embodiments, the signal coupler units in the transmitter of FIG. 1 and the demultiplexer unit 62 in the receiver of FIG. receiving, a transmission signal that is an N bit PCM signal, where N is equal to P.

A second embodiment of the signal splicing unit 24 in the transmitter of Fig. 1 employs the nested data method, which is well known, to associate a P bit PCM signal with a difference signal when the data is thus compressed to obtain a broadcast signal. The signal coupling unit forms a nested data channel in the P bit PCM signal. Said channel of the nested data channel is used for transmitting the difference signal. In an earlier receiver, the broadcast signal reproduces a replica of a digital signal that includes a nested data channel, but the data in the nested data channel is now not perceptible.

The second embodiment of the demultiplexer unit 62 in the receiver of Fig. 2 is adapted to derive a P bit PCM signal with a nested data channel and to derive a difference signal, if compressed so, from the nested data channel in said P bit PCM signal.

FIG. 5 shows a third embodiment of the signal splicing unit 24 in the transmitter of FIG. 1. The channel modulation unit 5-2 receives a P bit PCM signal through the first input 22 of the signal splicing unit 24 and processes the composite signal to obtain a sequence of m bit channel words. The channel modulation unit preferably comprises an n-m channel modulator. The generator unit 5.4 receives the difference signal received by the second input 26 of the unit and generates p pooling bits in the remaining portion. The unit 5.6 receives the splicing of the signal 24 in response to said sequence of m bit channel words and p bit bits and places the p bit bits between adjacent m bit channel words. to obtain a broadcast signal and output the signal to the output 28 of the signal coupling unit 24 for transmission by the TRM 3 transmission medium. 2. The ping bits are typically used to avoid a condition violation (d, k) between adjacent channel words and other DC control tasks. . After the previous one, there is still room to select one or more of these association bits in response to the information content of the difference signal. The generator unit uses this space to generate pool bits.

Fig. 6 shows a third embodiment of the demultiplexer unit 62 of Fig. 2. The unit 6.2 receives the transmission signal applied to the input 60 of the demultiplexer 62. The transmission signal comprises a sequence of m bit channel words with p bit bits between each adjacent m bit channel words. The unit 6.2 divides said broadcast signal into a sequence of m bit channel words and said p pooling bits. The sequence of the m bit channel words is passed to a channel demodulator unit 6.4 preferably adapted for m-n channel modulation to obtain a representation of the information signal. Representative signal, in the form of a standard digital stereo digital signal that is in P bit

The PCM samples are routed to the output terminal 64. The pooling bits p are routed to the processing unit 6.6. The processing unit 6.6 is adapted to process the p-bit bits to obtain a difference signal when the data is compressed, which is applied to the output terminal 66.

FIG. 7 shows a fourth embodiment of signal splice unit 24 in the transmitter of FIG. 1. Processing unit 7.2 receives a P bit PCM signal received by input 22 of signal splice unit 24 and processes the P bit PCM signal to obtain a sequence of byte blocks q. The processing unit may comprise a cross-interleaving Reed-Solomon encoder. Q is 32 for the standard format

CD. The encoder of sub-code 7.4 receives the difference signal when the data is thus compressed, applied to its input and generates a byte subcode in response to said difference signal. The standard CD subcode is essentially an auxiliary bitrate. At least one bit of said r byte subcode, e.g., U-subcode, is obtained in response to the difference signal. The unit 7-6 receives the Q byte block sequences and said r byte subcode and inserts the r byte subcode between adjacent m bit channel words to obtain a signal to be written on the record carrier 32. Before transmitting said signal to the carrier medium in the form of a carrier of the recording, the signal is preferably encoded, e.g., by an EFM encoder.

FIG. 8 shows a fourth embodiment of the demultiplexing unit 62 in the receiver of FIG. 2. The unit 8.2 receives a transmission signal that is input to the input 60 of the demultiplexing unit 62. FIG. The transmission signal comprises a sequence of q byte blocks with r byte subcodes between each time contiguous q byte blocks. The unit 8.2 divides said transmission signal into a sequence of byte blocks q and said r byte subcodes. The distribution is based on the physical position q of byte blocks and subcodes in the transmission signal. The byte-block sequence q is routed to a processing unit 8.4 which is arranged to process the byte-block sequence q to obtain a P bit PCM signal. Unit

The 8.4 processing can perform Reed-Solomon decoding and compression operations. The transmission signal, which may be in the form of a standard digital stereo signal, is applied to the output terminal 64. The transmission signal is provided by a digital signal. r byte subcodes are routed per processing unit 8.6. The processing unit 8.6 is arranged to process the r byte subcodes to obtain a difference signal, if so compressed, from at least one bit of the byte subcodes. The difference signal is applied to the output terminal 66 of the demultiplex unit 62.

FIG. 9 shows a transmitter in the form of an apparatus for recording a digital information signal on a record carrier. The circuit block designated 9.2 in FIG. 9 replaces the circuit diagram of FIG. 1. The input terminal 1 of the recording apparatus of FIG. 9 is thus equivalent to the input terminal 1 of FIG. 1 and the terminal 28 of FIG. 1. The recording apparatus further comprises recording means 9-4 for recording the output signal located at the terminal 28 on the record carrier 9.8. The record carrier 9.8 may be magnetic. In this case, the recording means 9.4 comprise one or more magnetic heads 9.6 for writing information in a track on the record carrier 9.8. In another embodiment, the record carrier 9 ♦ 8 is an optical record carrier. The recording means 9.4 then comprises an optical recording head for recording information onto a track on the optical record carrier. Generally, the signal to be recorded is channel-coded before recording, depending on the embodiment of the circuit block 9.2, the recording means 9.4 comprise a channel coding unit.

· To to to to to to to to to to to to to to

Fig. 10 shows a receiver in the form of an apparatus for reproducing a digital information signal from a record carrier. The circuit block, which is indicated in FIG. 10 by reference 10.4, replaces the circuit diagram of FIG. 2. Thus, the terminal 60 of the reproducing apparatus of FIG. 10 is equivalent to the input 60 of the demultiplexer 62 in FIG. The reproducing apparatus further comprises sensing means 10.2 for sensing the signal that is recorded on the record carrier 9.8 and for supplying the sensed signal to the input 60. FIG. The record carrier 9.8 may be magnetic. In this case, the sensing means 10.2 comprise one or more magnetic heads 10.6 for sensing the track information on the record carrier. In another embodiment, the record carrier 9.8 is an optical record carrier. The sensing means in this case comprises an optical head for reading information from the track on the record carrier. Generally, the signal removed from the record carrier is channel decoded before further processing. Depending on the receiver embodiment, the sensing means 10.2 comprise a channel decoding unit of the signal removed from the record carrier.

FIG. 11 shows another embodiment of a transmitter in the form of an apparatus for recording a digital information signal on an optical record carrier. The transmitter of Fig. 11 shows a great similarity to that of Fig. 1. The optical record carrier replaces the transmission medium. The signal coupling unit 24 of FIG. 11 comprises a first recording unit 11.2 and a second recording unit 11.4. The first recording unit 11.2 is adapted to receive the P bit PCM signal supplied by the splitting unit 8 to its input and to record the P bit PCM signal into the first channel of the record carrier.

· ♦ ···· ··>

· · · · · * * * * * * * * * * * * * * *

The record carrier thus obtained is thus preferably compatible with a standard audio CD, since the P bit PCM signal can be reproduced by a conventional CD player. In this case, the value of P should be 16. The first channel in this case is formed by optically detectable markers in the track, where the optically detectable markers are in the form of so-called pit. The second recording unit 11.4 is adapted to receive the difference signal supplied from the division unit 14, optionally also via the data compression unit 16, and also to record the difference signal, if such data is compressed, to a second channel on the CD record carrier. The second channel may be written in the form of changes in optically detectable markers across the track direction, eg, by varying the width of the markers. US Patent 5,724,327 discloses some embodiments of the second channel. The document describes changes in track position on the record carrier, changes in the width or depth of the track in the track, or changes in the frequency of the recovered data clock.

The advantage of this embodiment is that it creates record carriers, for example compact discs (CDs), which can be used in current standard CD players that reproduce a P bit PCM signal that is a representation of a lower quality M bit digital information signal. Even the CD recorders now available are only capable of scanning the first channel. The copies made by said CD recorders will contain only the data in the first channel and thus only a representation of the low quality M bit PCM digital information signal. The transmitter design creates a record carrier that includes copy protection of M bit PCM signal with high bandwidth and high bandwidth. · · ··· · ············ • · · rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš rozliš.

The first recording means 11.2 may optionally be adapted to insert the first part of the difference signal when the data is thus compressed into the P bit PCM signal to be recorded on the first channel on the record carrier. This insertion can be done by nested data method. In this case, the second recording unit is adapted to record the remaining portion of the difference signal into the second channel on the record carrier. This option increases the data capacity on the record carrier for transmitting the differential signal.

Fig. 12 shows another embodiment of a receiver in the form of an apparatus for reproducing an M bit PCM signal that is recorded by record carriers. The receiver of Fig. 12 shows a great similarity to that of Fig. 2. The demultiplexing unit 62 comprises a first sensing unit

12.2 and the second sensor unit 12.4. First scanning unit

12.2 scans the data recorded in the first channel on the record carrier to obtain a P bit PCM signal that is recorded in the first channel and leads said P bit PCM signal to the first input 68 of the signal splicing unit 70. Preferably said first channel is in the form of a channel carrying a N bit PCM signal on a standard CD where N = 16. The second read unit 12.4 reads the data recorded to the second channel on the record carrier to obtain a difference signal if the data is thus compressed to supply it to the second input 76 of the splice unit 70. If the second channel comprises a data compressed difference signal, said compressed signal is expanded before being applied to the second input 76 of the signal coupling unit 70. Embodiments of said second channel have already been described.

· 9 · «9 ·....................... · · ··· · · · · · · · · ·

The first read unit may optionally be adapted to read the first portion of the difference signal, if so compressed, from the signal removed from the first channel of the CD recorder, e.g., using the nested data method. In this case, the second sensor unit 12.4 is adapted to sense the remaining portion of the difference signal from the second channel on the record carrier. The second sensor unit is further adapted to couple the first portion and the remaining portion to obtain a difference signal when the data is thus compressed.

While the present invention is described with reference to preferred embodiments thereof, it is to be understood that these are not limiting cases. Various modifications may be apparent to those skilled in the art, but do not depart from the scope of the invention as defined in the claims. By way of example, the difference signal, when compressed in this way, may be divided into a first part and a remaining part, the first part may be stored in a nested data channel, while the remaining part may be stored eg in association bits or user bits. Copy protection can be implemented easily in the present invention. The difference signal can be scrambled with a specific key. The scrambled signal may be inserted into the nested data signal and stored in the first channel on the record carrier, while the scrambling key is stored in the second channel on the record carrier. With such an embodiment, the scrambled signal can be read and copied by current recording apparatuses, but the key cannot be read and therefore not copied. The copied record carriers carry a scrambled signal but do not carry a scrambling key. Since this scrambling key is missing, the reproducing apparatus of the present invention will not be able to 9. Decode a scrambled signal carrying a difference signal and thus will not be able to reproduce a high quality replica of the M bit PCM digital information signal and only sense the P bit PCM signal.

In addition, the difference signal may be in the form of a weightable signal. This has the advantage that the digital information signal can be recovered from the broadcast signal to a receiver of varying complexity. The complexity of the means to recover the difference signal determines the quality of the reproduced digital information signal. E.g. if it is transmitted, the differential reproduced quality will not be used than the digital information signal.

some less signal.

digital is the quality of the data-compressed difference signal of a portion of said digital signal by a complex decoder to produce this. The information signal will result in the signal having a lower original M bit

The word does not exclude the presence of elements or steps other than those set forth in the claim. No reference mark restricts the scope of the claims. The present invention can be implemented by both hardware and software. Several resources can be represented by the same hardware element. The present invention resides in any novel feature or combination thereof.

Claims (29)

Claims • 4 4 4 4 4 • · «·· * 4 · · · A transmitter for transmitting a digital information signal comprising M bit PCM samples, by a transmission medium, the transmitter comprising: input means for receiving an M bit PCM signal - means for dividing the M bit PCM signal to represent a digital information signal with P bit PCM samples and a difference signal that is the difference between the M bit PCM signal and the P bit PCM signal when kdy> P - first signal coupling means for coupling the P bit PCM signal and the difference signal in order to obtain a transmission signal for transmission by the transmission medium. 2. The transmitter of claim 1, further comprising a data compression unit for compressing the difference signal to obtain a data compressed difference signal. The first signal coupling means are adapted to couple the P bit PCM signal and the data compressed difference signal to obtain said transmission signal for transmission by a transmission medium. The transmitter of claim 1 or 2, wherein the first signal coupling means is adapted to obtain a broadcast signal comprising an N bit PCM signal that is a version of the P bit PCM signal when Ν> P. 4. A transmitter according to claim 1, 2 or 3, wherein the splitting means is adapted to divide the M bit PCM signal into the P most significant bits (MSBs) of the aforementioned bits. · · · · · · · • · • · • · ♦ · * * * * * * * * * * * A M bit PCM signal to obtain a P bit PCM signal and an MP of least significant bits (LSB) of said M bit PCM signal to obtain a difference signal. 5. The transmitter of claim 3 or 4, wherein N > P, wherein the signal coupling means is adapted to insert at least a portion of the difference signal (if the data is thus compressed) into the N-P of the least significant bits of the N bit PCM signal. 6. The transmitter of any one of the preceding claims, wherein the first signal coupling means is adapted to insert at least a portion of the difference signal (if the data is thus compressed) into a nested data channel in the P bit signal to obtain said broadcast signal for transmission. transmission medium. 7. The transmitter of any one of claims 2 to 6, wherein the data compression means comprises a psychoacoustic encoder, wherein the psychoacoustic encoder is adapted to compress the difference signal depending on the digital information signal to obtain a data compressed difference signal. 8. The transmitter of any one of claims 2 to 6, wherein the data compression means comprises entropy coding means. 9. The transmitter of claim 8 wherein said entropy coding means is in the form of a Huffnan encoder. • 4 • 44 4444 4 · 4 • 4 • 4 • 4 • 4 4 44 4 • • • 444 • 4 4 4 4 4 4 4 • S • 4 4 • 4 4 > 4 4 4 4 • 4 4 4 • 44 4 · 444 44 44 4 10. A transmitter according to any preceding claim, wherein the transmitter is in the form of an apparatus for recording a digital information signal on a record carrier. 11. The transmitter of any preceding claim, further comprising channel coding means for channel coding of the broadcast signal prior to transmission. 12. A record carrier formed by the transmitter according to items 10 or 11. 13. The record carrier of claim 12, wherein the record carrier is either optical or magnetic. A receiver for receiving a broadcast signal carrying a digital information signal from a broadcast medium and for generating a Q bit PCM signal from the broadcast signal, said Q bit PCM signal being a representation of said digital information signal, the receiver comprising: means for obtaining a broadcast signal from the broadcast medium - demultiplexing means for deriving a P bit PCM representation of the digital information signal and the difference signal from the broadcast signal - signal coupling means for coupling the P bit PCM signal and the difference signal so as to obtain a Q bit PCM signal where Q> P, output means for supplying a Q bit PCM signal. by being compressed for recovery, 15. The receiver of claim 14, characterized in that the demultiplexing means is provided with a difference signal that is data from the broadcast signal, the receiver further being equipped with data expansion means to obtain a difference signal that is data expanded. 16. The receiver of claim 14 or 15, wherein the demultiplexing means is adapted to extract the P bit PCM representation from the N bit representation of the digital information signal, where N> P. 17. The receiver of claim 16, wherein the N> P is characterized in that the demultiplexing means is adapted to extract the N-P of the least significant bits from the N bit PCM signal to obtain at least a portion of the difference signal (if the data is thus compressed). 18. The receiver of claim 15, 16 or 17, wherein the demultiplexing means is adapted to recover at least a portion of the difference signal (if so compressed) from the nested data channel in the P bit PCM signal. 19. The receiver of any one of claims 15 to 18, wherein the data expansion means comprises psychoacoustic decoding means. 20. A receiver according to any one of items 15 to 18, characterized in that the receiver according to any one of Claims 15 to 18 is characterized by: φ · φ φ φ · φ · · Φ φ se se se «« «« «tím tím« tím tím tím tím tím tím tím tím tím φ tím tím tím tím tím tím tím tím tím tím tím tím tím φ tím tím tím tím tím tím tím tím tím φ tím tím tím tím tím tím tím tím tím φ tím tím 21. The receiver of claim 20, wherein said entropy decoding means comprises a Huffman decoder. 22. The receiver of any one of claims 14 to 21 further comprising channel coding means located between the recovery means and the demultiplexing means. A method of transmitting a digital information signal with M bit PCM samples over a transmission medium, the transmission comprising the steps of: - receiving an M bit PCM signal - splitting the M bit PCM signal into a P bit PCM signal, which is a representation of the M bit PCM signal, and a difference signal that is the difference between the M bit PCM signal and the P bit PCM signal, where Μ> P combining the P bit PCM signal with the difference signal to obtain a transmission signal for transmission over the transmission medium. 24. The method of clause 23, further comprising the step of compressing the difference signal data to obtain a data compressed difference signal, and also wherein the combining step is adapted to combine the P bit PCM signal and the data compressed difference signal to obtaining said transmission signal for transmission by a transmission medium. · 9 9 9 9 9 · · · · · · · · · 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 ·· ·· ··· * · 25. The method of claim 23 or 24, wherein the coupling step provides a broadcast signal comprising an N bit PCM signal that is a version of the P bit PCM signal where N > P. 26. The method of claim 23, 24 or 25, wherein the step of splitting divides the M bit PCM signal into P most significant bits (MSBs) from said M bit PCM signal to obtain a P bit PCM signal and an MP least significant MP. bits (LSB) to obtain a difference signal. 27. The method of clause 25 or 26, wherein N > P, wherein at the splicing step, at least a portion of the difference signal (if the data is compressed) is inserted into the NP of least significant bits of the N bit PCM signal to obtain transmission by transmission medium. 28. A method according to any one of claims 23 to 27, wherein, in the joining step, at least a portion of the difference signal (if so compressed) is inserted into the nested data channel in the P bit PCM signal to obtain a broadcast signal. 29. The method of any one of items 24 to 28, wherein the data compression step comprises the step of psychoacoustic coding the difference signal depending on the digital information signal to obtain a data compressed difference signal.