Pulse or digital communications – Receivers
Reexamination Certificate
1999-05-11
2003-09-02
Chin, Stephen (Department: 2634)
Pulse or digital communications
Receivers
C375S345000
Reexamination Certificate
active
06614855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an apparatus for receiving broadcasting signals, and more particularly, is directed to an improvement in a broadcasting signal receiving apparatus which is operative to receive a broadcasting signal carrying synchronous data, control information data and plural groups of program information data and to reproduce desirous program information based on a group of data selected from the plural groups of program information data carried by the broadcasting signal received thereby.
2. Description of the Prior Art
Although an analog audio broadcasting system which includes an amplitude-modulated (AM) audio broadcasting system in which audio signals are transmitted in the form of an AM audio information signal and a frequency-modulated (FM) audio broadcasting system in which audio signals are transmitted in the form of a FM audio information signal, has been put to practical use for a long time in the field of audio broadcasting, there has been recently proposed to introduce a digital audio broadcasting system in which audio signals are transmitted in the form of a digital audio information signal for the purpose of improving quality of audio information transmitted or received in the system. Especially, in the region of Europe, the digital audio broadcasting system called “DAB” has been already put to practical use in some countries.
The digital audio information signal transmitted from a broadcasting station under the digital audio broadcasting system is called a digital audio broadcasting signal. The digital audio broadcasting signal carries not only audio information data forming a digital audio signal but also service information data representing service information, such as weather forecast, traffic information and so on, and further carries control information data which are necessitated for reproducing the digital audio signal based on the audio information data and the service information based on the service information data on the receiving side. Then, the digital audio broadcasting signal is a modulated wave signal obtained by modulating a carrier wave signal with digital data, such as audio information data, service information data, control information data and so on, in accordance with the Orthogonal Frequency Division Multiplexing (OFDM) system and the digital data transmitted by the digital audio broadcasting signal is composed of a series of frame units, each of which is called a transmission frame.
The transmission frame has a time duration of, for example, 24 ms and contains 77 segmental periods each named Symbol and identified with Symbol
0
to Symbol
76
, respectively, as shown in
FIGS. 1A
to
1
C. The Symbol
0
is a null Symbol where the modulated wave signal does not exist in actual fact. The Symbol
1
is a reference Symbol for synchronization. The Symbol
0
which is the null Symbol corresponds to about 324 &mgr;s and each of the Symbol
1
to the Symbol
76
corresponds to about 312 &mgr;s.
A channel named Synchronous Channel is allocated to the Symbol
0
and the Symbol
1
, a channel named Fast Information Channel (FIC) is allocated to the Symbol
2
to the Symbol
4
following the Symbol
1
, and a channel named Main Service Channel (MSC) is allocated to the Symbol
5
to the Symbol
76
following the Symbol
4
, as shown in
FIGS. 1A and 1B
. In the Synchronous Channel, synchronous information data DRS are transmitted by the Symbol
1
. The MSC is composed of a series of frames each named Common Interleaved Frame (CIF) for transmitting composite data DXD constituted by the audio information data and the service information data. The FIC is composed of a series of blocks each named First Information Block (FIB). The FIB contains a couple of portions of an FIB data field and an error checking word, and the FIB data field is composed of a series of groups each named Fast Information Groups (FIG). The FIC thus formed transmits control information data DCD representing multiplex configuration information (MCI) and other information.
Each of the audio information data and the service information data constituting the composite data DXD transmitted by the MSC contains various groups of program information data, such as program information data
1
to program information data N+M+2, as shown in
FIGS. 1B and 1C
.
Such a digital audio broadcasting signal as described above is received by use of a digital audio broadcasting signal receiver. In the digital audio broadcasting signal receiver, each of the digital audio broadcasting signals transmitted respectively from a plurality of broadcasting stations is received selectively through a tuning operation by a tuner and the received digital audio broadcasting signal is subjected to radio frequency (RF) amplification, frequency conversion, intermediate frequency (IF) amplification, digital demodulation, decoding processing and so on so that audio information data, service information data and control information data are obtained. Then, the audio information data or the service information data are further subjected to program selection, decoding processing and so on so that digital audio signals or service data are reproduced as desirous program information.
When the aforementioned reception of the digital audio broadcasting signal by the digital audio broadcasting signal receiver is practically carried out, usually one of plural groups of program information data contained in the audio information data or the service information data is selected and desirous program information is reproduced based on the selected program information data which are intermittently obtained. Accordingly, the digital audio broadcasting signal receiver is preferably required to be put in normal operation only in intermittent periods in each of which the desirous program information is reproduced based on the selected program information data.
However, in practice, a digital audio broadcasting signal receiver proposed previously is usually put in normal operation in not only the intermittent periods in each of which the desirous program information is reproduced based on the selected program information data but also other periods in each of which program information other than the selected program information is reproduced. This means that the digital audio broadcasting signal receiver proposed previously brings about power consumption in the periods in each of which program information other than the selected program information is reproduced and therefore the digital audio broadcasting signal receiver is not preferably required to be put in normal operation, in the same manner as in the intermittent periods in each of which the desired program information is reproduced based on the selected program information data. Since power consumption per unit time duration in the digital audio broadcasting signal is relatively large, the power consumption brought in the digital audio broadcasting signal receiver in such a manner as mentioned above excludes substantially the digital audio broadcasting signal receiver proposed previously from practical battery operation. That is, it is very difficult for the digital audio broadcasting signal receiver proposed previously to be formed in a portable type which is able to operate for a relatively long time with power supply from a battery.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus for receiving broadcasting signals, by which a broadcasting signal carrying synchronous data, control information data and plural groups of program information data is received and desired program information is reproduced based on a group of data selected from the plural groups of program information data carried by the received broadcasting signal, and which avoids the aforementioned disadvantages encountered with the prior art.
Another object of the present invention is to provide an apparatus for receiving broadcasting signals, by which a
Chin Stephen
Fan Chieh M.
Maioli Jay H.
Sony Corporation
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