Digital broadcast receiver

Details Digital broadcast receiver Digital broadcast receiver

1998-10-27

2002-06-25

Ton, David (Department: 2132)

Cryptography

Communication system using cryptography

Time segment interchange

Reexamination Certificate

active

06411712

ABSTRACT:

The transmission frame pursuant to the DVB standard utilizes the MPEG
2
Transport Stream. This transport stream is arranged with a consideration for transmitting a plurality of program signals by one stream, so as that the transport stream can utilize a plurality of reference times. The transport stream comprises a 188 byte fixed length packet (transport packet) including one byte synchronizing signal (hereinafter referred to as SYNC). In the DVB standard, MPEG
2
SYNC is used directly as a synchronizing byte of the transmission frame.
In the DVB standard, the transport stream is applied with the encryption, such as a scramble. In this case, the encryption is applied in a unit of a 188 byte length transport packet-basis.
In a receiver pursuant to the DVB standard, an IC card may be used for the decryption, such as a descrambling. It becomes possible to make a plurality of broadcast signal receivers commonly usable when the decryption is carried out using an IC card.
As an interface standard in the DVB standard, there is the Common Interface Standard (EN50221) which defines the interface format between receivers and IC cards. This standard defines the signal communication between the receiver main unit and an IC card in viewing a subscription TV channel wherein an encrypted broadcast signal, such as a scrambled broadcast signal is received by the receiver main unit and the decryption (decoding) is carried out by an IC card.
FIG. 1
is a block diagram showing a conventional digital broadcast receiver using such IC cards. Herein, a receiver main unit A
101
makes possible for users to view broadcast program by demodulating signals such as a satellite broadcast signal, a CATV broadcast signal, etc., supplied to an input terminal A
104
and then supplying the demodulated signal to a TV receiver.
Generally, there are two type of programs in a broadcast system, i.e., free program broadcasts and subscription program broadcast. In case of the subscription TV channel, the broadcast signal is encrypted by being encrypted in the broadcast station side and transmitted to the receiving apparatus side. When the receiving apparatus belonged to a subscription user receives the broadcast signal transmitted by being encrypted, it decrypted the broadcast signal by decrypting within the IC card loaded to the receiver main unit, so that it decodes the signal and supplies to the television receiver. Accordingly, the user is possible to view the broadcast program which is processed the encryption.
Concretely, to a turner/demodulator A
105
, shown in
FIG. 1
, the digital broadcast signal, which is frequency, multiplexed and time division multiplexed is supplied via the terminal A
104
. The tuner/demodulator A
105
selects the signal with a carrier frequency corresponding to the program signal selected by viewers, at the same time it demodulates it and supplies to an error corrector A
106
. Generally, on the transmission of the digital broadcast the error correcting code is added to the program signal. Accordingly, the error corrector A
106
corrects the error of the broadcast signal on its transmission channel. Generally, the signal stream supplied from the error corrector A
106
has a format conformable with the MPEG-SYSTEM (ISO/IEC13818-1) standard, time-division-multiplexing thereon a plurality of program signals. The signal stream is supplied to the signal processor
116
(decryptor) defined in an IC card A
102
, which is connected to the receiver main unit A
101
. The decryptor A
116
decrypts the signal stream, and then supplies the decrypted signal stream back to the receiver main unit A
101
.
The decryption of the stream signal in the IC card A
102
is carried out over a necessary portion on the stream signal where the encryption is needed, however, it is not carried out over the necessary portion. That is, the IC card A
102
decrypts only program signals assigned by viewers among the stream signal wherein a plurality of program signals are multiplexed. However, it supplies the other to the receiver main unit without decryption.
Here, in the digital broadcast receiver, it is possible to connect the several IC card according to the several subscription TV systems. The input and output signals between these IC cards are coupled with each other in so-called a daisy-chain fashion. That is, the output signal from the error corrector A
106
is decrypted as needed by the decryptor A
116
of the IC card A
102
, and supplied to a selector A
107
in the receiver main unit A
101
, then it is supplied to the IC card A
103
via the selector A
107
and supplied to a selector A
108
in the receiver main unit A
101
by being encrypted as needed by the decryptor A
117
of the IC card A
103
.
In
FIG. 1
, the decryptor is shown as the function of the IC cards A
102
and A
103
. However, at least two IC cards may be connected in the daisy-chain fashion, further, the application of the IC card may be the teletext receiving function or the external output interface.
Each of the IC cards A
102
and A
103
communicates between a controller A
113
inside the receiver main unit A
101
via each of controllers A
118
and A
119
in order to control each of the descrablers A
116
and A
117
.
When the broadcast signal which is carried out the signal processing (decryption) by each the IC cards A
102
and A
103
is supplied to the receiver main unit A
101
, a demultiplexer A
109
(demultiplexer) selects the required signal among the time division multiplexed broadcast signal and supplies it to an audio/video decoder A
110
. The audio/video decoder A
110
denotes the digital compression encoded audio/video signal and supplies it to an audio/video output processor A
111
. The audio/video output processor A
111
carries out a D/A conversion and a system conversion and supplies the broadcast signal to the television receiver via a terminal A
112
. Accordingly, viewers can view his/her favorite broadcast program.
The IC cards A
102
and A
103
are removable to the receiver main unit A
101
, so that viewers use the apparatus by removably coupling several kinds of IC cards according to the purpose. The loading/unloading of the IC cards A
102
, A
103
is detected by each of IC card detectors A
114
and A
115
in the receiver main unit A
101
. The controller A
113
in the receiver main unit A
101
then controls the selectors A
107
and A
108
in response to the detection outputs from the IC card detectors A
114
, A
115
.
Concretely, when the unloaded status of both the IC cards A
102
and A
103
are detected by the IC card detectors A
114
and A
115
(in the case of that the IC card is not put on the receiver main unit A
101
), the controller A
113
controls the selector A
107
in order to select the broadcast signal, at the same time, it controls the selector A
108
in order to select the broadcast signal via the selector A
107
. Accordingly, since the broadcast signal is supplied to the television receiver without encryption, viewers may not view his/her favorite broadcast channel.
Further, when the unloaded status of the IC card A
102
is detected only in the IC card detector A
114
(in case of that only the IC card A
103
is put on the receiver main unit A
101
), the controller A
113
controls the selector A
107
in order to select the broadcast signal supplied from the error corrector A
106
, at the same time, it controls the selector A
108
in order to supply the broadcast signal via the selector A
107
to the IC card A
103
. Then, it controls the selector A
108
in order to select the broadcast signal which is encrypted by the IC card A
103
. Accordingly, the broadcast signal which is decrypted according to the IC card A
103
is supplied to the television receiver, so that viewers can view his/her favorite broadcast program.
Further, when the unloaded status of the IC card is detected in only the IC card detector
115
(in case of that only the IC card A
102
is put on the receiver main unit A
101
), the controller A
113
controls the selector A
107
in order to supply the broadcast signal supplied from the error correct

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