JP4633208B2 - Receiving apparatus and receiving method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus and a receiving method suitable for use in, for example, digital cave broadcasting that retransmits a digital CS broadcast signal or the like.
[0002]
[Prior art]
In the current cable broadcasting, original materials such as terrestrial broadcasting, BS (Broadcasting Satellite) broadcasting, and CS (Communication Satellite) broadcasting are retransmitted. In the analog cable broadcasting, any original material is retransmitted with the same modulation method, so there is no need to consider the modulation method in the demodulation process on the receiving device side.
[0003]
In recent years, digital CS broadcasting services have been started, and cable broadcasting has been digitized accordingly. In digital cable broadcasting for retransmitting digital CS broadcasting, the 64QAM (Quadrature Amplitude Modulation) method is adopted as a digital modulation method. For this reason, in digital cable broadcasting in which only digital CS broadcasting is retransmitted, it is only necessary to perform modulation corresponding to the 64QAM system on the receiving device side, and there is no need to perform demodulation processing in consideration of the modulation system.
[0004]
[Problems to be solved by the invention]
In digital CS broadcasting, it has been studied to increase the data transmission rate by reducing the Viterbi code rate as the CS transmission output increases. Corresponding to this, 64QAM is used as a modulation method when performing retransmission using a cable. It may be necessary to adopt something other than.
[0005]
In addition, when digital BS broadcasting, digital terrestrial broadcasting, etc. are started and these broadcast signals are retransmitted in digital cable broadcasting, a plurality of types are applied in digital cable broadcasting in accordance with the modulation method in each broadcasting signal. Therefore, it is necessary to perform demodulation processing in consideration of a plurality of types of modulation schemes on the receiving device side.
[0006]
Accordingly, an object of the present invention is to provide a receiving apparatus and a receiving method capable of accurately performing reception processing such as demodulation on a plurality of types of digital broadcast signals having different transmission specifications such as modulation schemes and frequencies. There is.
[0007]
[Means for Solving the Problems]
The invention of claim 1 includes a receiving means for receiving a digital broadcast signal to be subjected fed,
Input means for inputting reception parameters usable for receiving a digital broadcast signal as initial setting values ;
When the reception parameter is changed, the change is notified to the user, and a new initial setting value corresponding to the change is input by the input means.
Obtain information related to the reception parameter included in the digital broadcast signal received by the operation of the receiving means under the initial setting value, and set the reception parameter associated with the channel switching process according to the acquired information related to the reception parameter. automatically have rows,
The information related to the reception parameter is a reception device that is an NIT .
[0009]
The invention of claim 5 includes the steps of inputting a reception parameter that can be used to receive a digital broadcast signal to be subjected fed as an initial setting value,
Informing the user of the change when the reception parameter is changed, and inputting a new initial setting value corresponding to the change;
A receiving step for receiving a digital broadcast signal under an initial set value;
Obtaining information related to reception parameters included in the digital broadcast signal received by the reception step,
According to the acquired information according to the received parameters, it had automatically make settings of the receiver parameters involved in the process of switching channels,
The information related to the reception parameter is a reception method that is NIT .
[0011]
According to the invention as described above, in order to receive a digital broadcast signal such as a digital cable broadcast signal by a user input or the like or by a trial and error selection from a plurality of reception parameters stored in advance in a memory. Usable reception parameters are set, and reception parameters associated with channel switching processing according to information relating to reception parameters such as NIT acquired from the digital broadcast signal received under the reception parameters set in this way Is automatically set.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A digital CS broadcast service has already been started, and a digital cable broadcast for retransmitting the digital CS broadcast is being performed. Here, the transmission path of the digital cable broadcast and the configuration on the receiving device side will be briefly described. For example, a dedicated adapter called a set top box is used on the receiving device side. The set top box includes, for example, a tuner circuit, a QAM receiving circuit, an error correction circuit, a decoder corresponding to MPEG (Moving Picture Experts Group), an encoder according to the NTSC (National Television System Committee) system, an audio decoder, a D / A converter, It is composed of a host processor, a switch circuit and the like, and is used by being placed on a television receiver. As a transmission path to the set box, for example, a conventional cable broadcasting network that distributes television broadcasting using a coaxial cable is used as it is.
[0013]
In the digital cable broadcasting station, a video database in which digitized video information is stored is provided, and the video information in the video database is supplied to one input terminal of the mixer via a 64-value QAM modulator. . In addition, an analog television broadcast signal is supplied from the existing analog cable broadcasting station to the other input terminal of the mixer. In the mixer, the digital QAM modulation output and the analog television broadcast signal are mixed, and the output of the mixer is supplied to the optical transmitter. In the optical transmitter, the output of the mixer is modulated by a predetermined modulation method and supplied to the optical receiver via the optical fiber. The received output is demodulated in the optical receiver, and the demodulated output is distributed to each contracted home via a plurality of amplifiers as repeaters and a coaxial cable connecting them.
[0014]
Each video device is connected to a coaxial cable drawn into the home. For example, as one connection form, a coaxial cable is connected to a VTR (Video Tape Recorder), and a television receiver is connected to the VTR. As another connection mode, a coaxial cable is connected to the set top box, and a television receiver is connected to the set top box. In the case of the connection form using this set-top box, it is possible to selectively view conventional analog cable broadcasting and digital cable broadcasting.
[0015]
In digital CS broadcasting, a QPSK (4-phase phase modulation) system is adopted as a digital modulation system. For example, in the case of “SkyPerfecTV!” Which is one of digital CS broadcasts, the data is transmitted in a 27 MHz band, and the total data transmission rate including an error correction code called a Viterbi code is 42.192 Mbps. The rate excluding this is defined as 31.644 Mbps. In such a digital cable broadcast that retransmits the digital CS broadcast, the transmission band is 6 MHz, and the C / N of the cable is considerably better than the C / N of the CS broadcast, and thus no Viterbi code is included. 64-value QAM is used as a modulation method.
[0016]
QAM is one of digital modulation methods called quadrature amplitude modulation, and is a method in which each of two orthogonal carriers (I and Q) is subjected to digital amplitude modulation in multiple values, and I and Q are added and transmitted. . The 64-value QAM is called in this way because I and Q are digital amplitude modulated to 8 values and 64 data are developed on the IQ plane. By modulating 31.644 Mbps data using this 64-value QAM modulation system, it is possible to transmit at a transmission band of 6 MHz of the cable.
[0017]
By the way, in digital CS broadcasting, it has been studied to increase the data transmission rate by reducing the Viterbi code rate in accordance with the increase in CS transmission output. There is a problem like this. That is, in this case, if 64QAM is used, the band of 6 MHz is exceeded, and therefore, it is necessary to perform modulation using multivalued 128QAM or 256QAM. FIGS. 1A, 1B, and 1C show data arrangements on the QI plane of digital signals modulated by 64 QAM, 128 QAM, and 256 QAM, respectively.
[0018]
In addition, when digital services other than digital CS broadcasting such as digital BS broadcasting and terrestrial digital broadcasting are started, it may be necessary to use a modulation method other than 64QAM in digital cable broadcasting for retransmitting those digital services. There is also.
[0019]
In view of this, the present invention enables a plurality of types of digital broadcast signals having different modulation methods, frequencies, and the like to be accurately received by a single digital receiver. FIG. 2 shows an example of the overall configuration of a digital cable broadcast receiving apparatus according to an embodiment of the present invention. A digital cable broadcast signal is input to the front end unit 2 through an input terminal 1 to which a coaxial cable of a digital cable broadcast network is connected. The front end unit 2 selects a predetermined carrier wave from the received signals based on control information from the host processor 5.
[0020]
Further, the front end unit 2 performs a demodulation process corresponding to the modulation process performed on the transmission side, and performs an error correction process corresponding to the encoding process performed on the transmission side. A transport stream obtained by such processing is supplied to the transport unit 3. The transport unit 3 includes a descrambler 31, a demultiplexer 32, and the like. Based on the control information from the host processor 5, the descrambler 31 performs the descrambling process when the separated signal component has been scrambled on the transmission side. By this descrambling process, an MPEG compression encoded signal obtained by applying MPEG compression encoding to video data and / or audio data to be viewed is restored.
[0021]
The output of the descrambler 31 is supplied to the demultiplexer 32. The demultiplexer 32 performs separation / extraction processing of necessary packets such as video data and / or audio from the output of the descrambler 31 based on control information from the host processor 5. By such processing, individual packets in a format called PES (Packetized Elementary Stream) related to a desired channel are separated from each channel multiplexed in the transport stream.
[0022]
MPEG-compressed video data and / or audio data of the separated channel obtained as a result of the above-described processing by the transport unit 3 is supplied to the MPEG decoding unit 4. Based on the control information from the host processor 5, the MPEG decoding unit 4 performs a decoding process or the like according to a process performed on the transmission side to form an analog video output and also an audio output. The MPEG decoding unit 4 includes a video decoder 41, an audio decoder 42, an NTSC encoder 43, a D / A converter 44, and the like. The individual packets in the PES format separated by the demultiplexer 32 are supplied to the video decoder 41 and / or the audio data decoder 42.
[0023]
The video decoder 41 decodes the MPEG-compressed signal, and this decoded output is passed through the NTSC encoder 43 to form a reproduced video signal. This reproduced video signal is taken out via the output terminal 9. On the other hand, in the audio decoder 42, a digital audio signal is formed, and this digital audio signal is passed through the D / A converter 20 to be a reproduction audio signal of analog left and right channels. This reproduced audio signal is taken out via the output terminal 10.
[0024]
Note that the reproduced video signal and the reproduced audio signal extracted via the output terminals 9 and 10 are supplied to, for example, an RF modulator (not shown), and the reproduced video signal and the reproduced audio signal are output from the RF modulator. The reproduction television signal is formed by RF modulation, and this reproduction television signal is supplied to the antenna terminal of the television receiver.
[0025]
Further, as described above, the host processor 5, the front end unit 2, the transport stream unit 3, and the MPEG decoding unit 4 that control each unit are connected by a bus, and can exchange data bidirectionally. It is possible. The host processor 5 is connected to an operation input unit 7 having various setting switches, a numeric keypad, and the like, and setting information from the operation input unit 7 is supplied. Therefore, the host processor 5 stores the setting information corresponding to the operation state of the operation input unit 7 in the nonvolatile memory 6 and reads the data stored in the nonvolatile memory 6 as needed to obtain the control information. Each unit is centrally managed by forming and supplying this control information to each unit.
[0026]
Next, the front end unit 2 will be described in more detail. The front end unit 2 includes a tuner 21, a QAM demodulation circuit 22, an error correction circuit 23, and the like. The tuner 21 receives a digital cable broadcast signal supplied via the input terminal 1, selects a desired carrier wave from the received signal, and converts the selected carrier wave into an intermediate frequency signal. An intermediate frequency signal that is an output of the tuner 21 is supplied to the QAM demodulation circuit 22. The QAM demodulating circuit 22 performs QAM demodulation processing corresponding to the modulation processing performed on the transmission side on the supplied intermediate frequency signal, thereby forming baseband digital data. Baseband digital data that is the output of the QAM demodulating circuit 22 is supplied to the error correcting circuit 23. The error correction circuit 23 performs error correction processing on the supplied digital data according to the encoding processing performed on the transmission side. As an output of the error correction circuit 23, a transport stream output is formed.
[0027]
Specifically, the transport stream output from the front end unit 2 is a bit string defined in the MPEG system, and is composed of a set of 188-byte fixed-length packets. Each packet consists of a header, an adaptation field for entering additional information in a specific individual packet, and a payload representing the packet contents (video / audio, etc.). The header consists of 4 bytes, and is always synchronized at the beginning. Bytes are arranged, and control information such as PID (Packet ID) which is identification information of the packet, presence / absence of scramble, subsequent adaptation field and presence / absence of payload is stored.
[0028]
Based on these control information, the descrambler 31 performs descrambling for each packet. Then, the demultiplexer separates and extracts necessary packets such as video / audio / data. Each packet separated and extracted by the demultiplexer 32 is supplied to the MPEG decoding unit 4. Note that the output of the descrambler 31 is taken out through the terminal 8 as a high-speed data output.
[0029]
A channel selection process according to an embodiment of the present invention will be described below. In general channel selection processing in digital CS broadcasting or the like, an information table called NIT (Network Information Table), particularly information necessary for channel selection called PSI (Program Specific Information) in a transport stream is provided. To be acquired. The PSI is composed of four types of tables, and each table is represented in a format called a section format that conforms to the MPEG system. In one NIT of these four tables, the same content is multiplexed on all carriers, transmission parameters for each carrier (polarization plane, carrier frequency, convolution rate, etc.), and all digital transmissions multiplexed there A list of channels is described.
[0030]
FIG. 3 is a flowchart showing an example of a tuning process procedure according to the embodiment of the present invention. The processing shown in FIG. 3 is performed by the host processor 5, for example. A reception parameter capable of receiving a channel confirmed to be transmitted in digital cable broadcasting is input as a default value by the user via the operation input unit 7 or the like (step S1). Channel selection is performed according to the channel reception parameters input in step S1 (step S2). The NIT is separated and extracted from the transport stream related to the channel selected in step S2, and the NIT is stored in the nonvolatile memory 6, thereby completing the acquisition of the NIT (step S3). Then, an image sound display relating to the selected channel is made (step S4).
[0031]
Thereafter, when the operation input unit 7 is operated by the user and a channel change instruction is given, the reception parameters of the new channel related to the channel change are confirmed with reference to the NIT stored in the nonvolatile memory 6. (Step S6). Then, it is determined whether or not the reception parameter needs to be changed (step S7). If it is determined that the reception parameter needs to be changed, the process proceeds to step S8. Otherwise, the process proceeds to step S9. In step S8, for example, a register setting in the host processor 5 related to the control of the front end unit 2 is changed, and the process proceeds to step S9. In step S9, a channel selection operation is performed based on the control information of the register whose setting has been changed or held according to the determination result of step S7, and then the process proceeds to step S3.
[0032]
Through the processing as described above, reception parameters are set for the front end unit 2 along with the channel change. This makes it possible to accurately receive digital cable broadcast signals in response to channel changes. For this reason, the user can seamlessly change the channel without being aware of the change of the reception parameter. Unless the reception parameters such as the frequency are changed on the transmission side, accurate reception as described above is always possible by repeatedly referring to the NIT held in the nonvolatile memory 6. Therefore, as long as reception parameters such as frequency are not changed on the transmission side, all the channels can be accurately received by inputting the default value in step S1 only once. That is, steps S1 and S2 surrounded by a dotted line in FIG. 3 need only be performed once unless the reception parameters such as the frequency are changed on the transmission side.
[0033]
Note that the image data display state data of the predetermined channel in step S4 is stored in the nonvolatile memory 6 together with the NIT held in step S3 when the power is turned off, and the stored data in the nonvolatile memory 6 is read when the power is turned on again. To return to the previous power-off state, and the processing from step S4 is started.
[0034]
In addition, when the reception parameter such as frequency is changed for some reason on the transmission side, the change is notified to the user, and a new default value corresponding to the change is input, that is, the step is executed under the new default value. By performing S1 and step S2, it is avoided that reception becomes impossible.
[0035]
Further, since the unused channels differ depending on the cable broadcasting company, it is assumed that the transmitted channel is not uniform depending on the company. In such a case, the processing described above with reference to FIG. When doing, it can respond to any provider.
[0036]
Further, FIG. 3 illustrates the case where the process proceeds to step S3 after performing step S9 to acquire the NIT again, but the process may proceed to step S4 after step S9. In this case, similarly to steps S1 and S2, step S3 need only be performed once unless the reception parameters such as frequency are changed on the transmission side. Accordingly, the processing procedure is simplified. However, when the reception parameters related to some channels are changed during viewing, a new NIT cannot be acquired, and as a result, the default value input in step S1 is performed. There is also a problem that the number of times of performing the operation may increase.
[0037]
Next, another embodiment of the present invention will be described. The overall configuration of another embodiment of the present invention is the same as that of the above-described embodiment of the present invention. FIG. 4 shows an example of the tuning process procedure operation in one embodiment of the present invention. Steps that perform the same processing as each step in FIG. 3 are given the same reference numerals. In step S11, step S12, step S13, and step S14, channel selection for acquiring NIT is performed in the same manner as the procedure shown in FIG. These steps surrounded by a dotted line need only be performed once as long as reception parameters such as frequency are not changed on the transmission side, as in the case of FIG.
[0038]
That is, in step S11, reception parameters such as frequency are initialized. In step S12, channel selection is performed. Furthermore, the process proceeds to step S13, where it is determined whether or not channel selection has been performed accurately. If channel selection has been performed accurately, the process proceeds to step S3. In other cases, the process proceeds to step S14 to change the parameters.
[0039]
That is, for example, reception parameters stored in a predetermined memory such as the nonvolatile memory 6 at the time of shipment are sequentially set in step S14. Then, the process proceeds to step S12, and channel selection is performed under the reception parameters set in step S14. Here, in the predetermined memory such as the nonvolatile memory 6, the reception parameters as combinations of all frequencies and modulation schemes that are expected to be used in digital cable broadcasting are set in the predetermined memory such as the nonvolatile memory 6. Pre-stored in memory. By such processing, a search for an appropriate reception parameter is automatically performed until it is determined that channel selection has been performed accurately.
[0040]
Each step after step S3 is the same as each step S in the embodiment of the present invention shown in FIG. In other words, the processing after it is determined that the channel selection has been performed accurately is the same as in the embodiment of the present invention. The NIT is acquired, and the operation for channel change or the like based on the acquired NIT is performed. Processing to automatically follow is performed.
[0041]
The other embodiment of the present invention has an advantage that the user does not have to input the default value (step S1) as compared with the above-described embodiment of the present invention. As a result, it is necessary to assume changes in reception parameters in a wide range in advance, and as a result, a predetermined memory such as the nonvolatile memory 6 having a large memory capacity is required, which may hinder cost reduction. There are problems such as.
[0042]
In the above-described embodiment of the present invention and the other embodiments of the present invention, a case has been described in which signals modulated by 64-value QAM, 128-value QAM, and 256-value QAM are supplied as different modulation schemes. The present invention can also be applied to other modulation schemes.
[0043]
In the above-described embodiment of the present invention, a digital signal using an error correction code of a digital CS broadcast signal configured as a concatenated code using a Reed-Solomon code as an outer code and a convolutional code as an inner code is received. However, the present invention can also be applied to receiving a digital signal using an error correction code other than this. That is, the present invention can also be applied to a case where a plurality of types of digital signals having different error correction coding methods are handled.
[0044]
In addition, one receiver is configured to have a function of performing both the operation according to the embodiment of the present invention and the operation according to the other embodiment of the present invention, and one of these two types of operations is performed. The channel selection mode may be selected.
[0045]
【The invention's effect】
According to the present invention, reception that can be used for receiving a digital broadcast signal such as a digital cable broadcast signal by input by a user or by selection by trial and error from a plurality of reception parameters stored in advance in a memory. The parameter is set, and the reception parameter setting associated with the channel switching process is automatically performed according to the information related to the reception parameter such as NIT acquired from the digital broadcast signal received under the reception parameter set in this way. Done.
[0046]
Therefore, for example, even when reception parameters such as frequency and modulation method are different for each channel, a single digital receiver can accurately perform reception processing corresponding to all channels.
[0047]
Also, a change in reception parameters associated with the channel switching process is automatically performed according to the acquired MNIT or the like, and a seamless channel change is realized.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a modulation method in digital cable broadcasting.
FIG. 2 is a block diagram showing an example of the overall configuration of an embodiment of the present invention.
FIG. 3 is a flowchart for illustrating a channel selection process according to an embodiment of the present invention.
FIG. 4 is a flowchart for illustrating a channel selection process in another embodiment of the present invention.
[Explanation of symbols]
2 ... Front end part, 3 ... Transport part, 5 ... Host processor, 6 ... Non-volatile memory, 7 ... Operation input part

Claims (5)

Receiving means for receiving a digital broadcast signal to be subjected fed,
Input means for inputting a reception parameter usable for receiving the digital broadcast signal as an initial setting value ;
When the reception parameter is changed, the user is notified of the change, and a new initial setting value corresponding to the change is input by the input means.
Obtaining information related to the reception parameter included in the digital broadcast signal received by the operation of the receiving means under the initial setting value, and receiving accompanying the channel switching process according to the obtained information relating to the reception parameter automatically have line the setting of the parameters,
The information related to the reception parameter is a reception device that is a NIT . In claim 1,
The digital broadcast signal is
A receiver which is a digital cable broadcast signal in a digital cable broadcast for retransmitting a digital CS broadcast signal. In claim 1,
Storing the acquired information related to the reception parameter in a predetermined storage means;
A receiving apparatus that reads information related to the reception parameter from the storage means during the channel switching process. In claim 1,
Storing information related to the reception parameter in a predetermined storage means;
Each time the channel switching process is performed, the receiving apparatus acquires information related to the reception parameter from the digital broadcast signal. Inputting a reception parameter that can be used to receive a digital broadcast signal to be subjected fed as an initial setting value,
Informing the user of the change when the reception parameter is changed, and inputting a new initial setting value corresponding to the change;
A receiving step for receiving the digital broadcast signal under the initial setting value;
Obtaining information related to reception parameters included in the digital broadcast signal received by the reception step,
Accordance with the acquired information according to the received parameter, have automatically make settings of the receiver parameters involved in the process of switching channels,
The reception method in which the information related to the reception parameter is NIT .

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