JPH11308133A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use a battery in a receiver for an FM teletext broadcasting. SOLUTION: A tuner 11 receives FM taletext broadcasting. Telext broadcasting data is extracted and is supplied to a decoder 14. Data is decoded in the decoder 14 and an error is detected by a CRC(cyclic redundancy check) code for every packet. Valid packets are counted based on an error detection flag. When more than prescribed packets are obtained in the counting period of two seconds, a switching element 21 is turned on based on the control of CPU 15 for next five seconds. Power 30 is supplied to the decoder 14. When the number of packets obtained in two seconds of counting does not reach the prescribed one, the switching element 21 is turned off for next five seconds and the supply of the power of the decoder 14 is stopped. Thus, sequence for seven seconds is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus for receiving an FM teletext multiplex broadcast by superimposing a text broadcast on an FM broadcast and transmitting it.

[0002]

2. Description of the Related Art In recent years, FM text multiplex broadcasting, in which text broadcasting using character data is multiplexed with FM broadcasting and broadcasted, has become widespread. In FM text multiplex broadcasting, digitally modulated data is multiplexed to a higher frequency than a sub-channel signal of FM broadcasting and broadcast. The data broadcast by the FM teletext broadcasting includes a wide variety of data such as character data, display attribute information of the character data, and graphic data.

[0003] At present, in Japan, DARC (Data Radio Channel) is applied as a standard for FM teletext broadcasting. According to this DARC, the data is (272, 19
0) Error correction coding is performed using a product code using a shortened difference set cyclic code, and further packetized in predetermined units. LMSK (Level controlled Minimum Shift Keyin
g) Digitally modulated by the method and superimposed on FM broadcast at a subcarrier frequency of 76 KHz and broadcast.

[0004] As a receiving device for receiving the FM teletext, a small portable device, a stationary device,
Alternatively, there is a vehicle-mounted one. The receiving device includes a tuner for receiving a normal FM broadcast, a decoder corresponding to the FM teletext broadcasting, and a display device. As a display device, for a portable receiving device, for example, an LCD (Liquid Crystal Display) is used. In a stationary receiver, a CRT or the like can be used.

[0005] In the receiving apparatus, the FM text multiplex broadcast received by the tuner is reproduced by a sound processing unit and data is decoded by a decoder. The decrypted data is displayed on a display device. By temporarily storing the decrypted data in the memory, information can be displayed even if the reception is temporarily interrupted.

[0006]

By the way, in FM teletext broadcasting, since text information can be easily obtained,
As a receiving device, a small portable device has been widely used.
Such a portable receiving device is supplied with power from a battery such as a dry battery or a rechargeable battery. for that reason,
The circuit of the receiving device is required to consume as little power as possible.

In a conventional receiving apparatus, power is always supplied to each part of the apparatus regardless of the quality of the receiving state. Therefore, in the reception of FM teletext,
Regardless of whether valid data is received, there is a problem that the battery life is the same.

That is, even when the reception state is poor and the display by the FM text multiplex broadcasting is delayed, the same power is consumed as in the case where the reception is normally performed and the display is performed, and the battery is consumed needlessly. There was a problem.

Accordingly, an object of the present invention is to provide an FM teletext receiving apparatus capable of effectively utilizing a battery.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a receiving apparatus for receiving a text broadcast superimposed on an FM broadcast. A receiver comprising: decoding means for decoding data; determining means for determining an output from the decoding means at a predetermined cycle; and power supply controlling means for controlling a power supply of the decoding means based on a result of the determination by the determining means. It is.

As described above, according to the present invention, the output from the decoding means for decoding the text broadcast data superimposed on the received FM broadcast is judged at a predetermined cycle, and the power of the decoding means is turned on based on the judgment result. Since the control is performed, supply of power to the decoding means can be cut off while valid data is not received.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, in order to facilitate understanding, a data structure of FM teletext broadcasting based on the DARC system will be described with reference to FIGS. This data structure conforms to ITU-R Recommendation 807 “Reference Model for Data Broadcasting”, and includes a physical layer (layer 1), a link layer (layer 2), a network layer (layer 3), and a transport layer (layer 4). , A session layer (layer 5), a presentation layer (layer 6), and an application layer (layer 7).

The application layer is data of services provided by FM text multiplex broadcasting, such as various characters, graphic information, and traffic information. In the presentation layer, a coding system for transmitting data of the application layer by FM teletext broadcasting is defined. An 8-unit coding system and a transparent system using image data or the like are used.

FIG. 1A shows the session layer. The data of the presentation layer is grouped as a data unit group composed of a plurality of data units divided for each encoding, and a data header and an information separation code RS are added. The header indicates a program number, a type of data included in the program, and the like. A data group is composed of the data unit group, the data header, and the information separation code RS.

FIG. 1B shows the transport layer. The size of the data group is added as a header to the data of the data group in the session layer. SOH indicates the head of the data group, and ETX indicates the end of the data group. ETX includes a code for error detection of a data group together with an end code.

The data group corresponds to one display unit, that is, one page of data, and is composed of one or a plurality of data blocks as shown in FIG. One data block is 18 bytes (144 bits) in length
It is said. In the network layer shown in FIG. 3, a 32-bit prefix is added to each data block to form one data packet.

The prefix includes a data packet number, a data group number, service identification information, an information end flag indicating the end of the data group, an update flag that is incremented when the data group is updated, and the like. In the data packet, the data blocks having the same service identification information, the same data group number, and the same update flag are added in the data packet number order in the data packet number

By arranging from [0] to the data block with the information end flag set, one data group is formed.

FIG. 4 shows the link layer. As described above, in FM teletext broadcasting by the DARC method,
Error correction coding is performed using a product code using a (272, 190) shortened difference set cyclic code. This error correction coding is performed in the link layer.

The information section corresponds to a data packet. A 14-bit CRC (Cyclic Redundancy Check) code for performing error detection is attached to the data packet. The CRC code is for confirming whether or not error correction by the product code has been completely performed at the time of decoding. As shown in FIG. 4, 190 sets of data packets and CRC codes are arranged in a matrix, and a 82-bit row parity is generated in a row direction by a shortened difference set cyclic code, and further, a column direction is generated. , A column parity of 82 bits is generated and product-coded. At the head of each row, a 16-bit block identification code for identifying each row is attached.

As described above, one frame, which is a unit of transmission, is formed by product-coding 190 packets.
As is well known, in FM broadcasting, main and sub channel signals forming left and right stereo signals are arranged on both sides of a pilot signal having a sub carrier frequency of 19 KHz. In order not to affect these signals, a subcarrier frequency of 76 KH higher than the subcarrier frequency of the subchannel signal is used.
z is modulated by the data of the FM teletext. As a modulation method, an LMSK method in which a level after modulation is changed according to a signal level is used. The bit rate is 16 kbits / s, and 288 bits ×
It takes about 5 to transmit one frame consisting of 272 bits.
Seconds spent. FIG. 5 shows each signal by the physical layer.

The main carrier frequency of FM teletext broadcasting is shown in FIG.
Are modulated and transmitted. The transmitted radio wave is received by the corresponding receiving device, and the main carrier frequency is demodulated. The main channel signal and the sub channel signal are processed by the audio processing circuit and output as an audio signal.

On the other hand, the data of the teletext is decoded with an error correction code and stored in a memory, for example. Then, the data is arranged in a correct order based on the prefix of the data packet, subjected to predetermined processing to be display data, and displayed on a display device such as an LCD.

FIG. 6 shows an example of the configuration of an FM teletext receiver 1 according to this embodiment. The radio wave of the FM teletext received by the antenna 10 is the tuner 1
In step 1, FM detection is performed, and a signal is extracted. The audio signal is
The audio is processed by an audio processing circuit 12 including an amplifier and the like, and reproduced by a speaker 13. The speaker 13 may be an earphone, for example.

The detection output from the tuner 11 is passed through, for example, a band-pass filter (not shown) to extract character multiplexed data centered on a subcarrier frequency of 76 KHz, and is supplied to a decoder 14. Decoder 14
Then, the supplied signal is decoded and output as the data of the hierarchy 3 level shown in FIG.

That is, in the decoder 14, for example, the supplied signal is arranged so as to form one frame based on the block identification code, and is temporarily stored in the memory. When one frame is accumulated, decoding of the error correction code is performed. After being decoded, error detection is performed using a CRC code. The detection result is represented by a 1-bit error detection flag of "1" for each packet, for example, if there is an error, and "0" if there is no error. The data and the error detection flag thus decoded and made only the information portion are, for example, bit serial data, and supplied to the CPU 15 for each packet. The error detection flag is added, for example, to the head of the packet.

The data supplied to the CPU 15 is stored in a RAM
17 is stored. Further, the CPU 15
Information to be displayed is read from M17. Based on the read data, corresponding display data is created from data stored in the ROM 16 in advance. The created display data is displayed on the LCD 18.

The input unit 19 includes various keys and dials, and gives an instruction from the user to the CPU 15. The indicator 20, which will be described in detail later, is displayed when FM teletext broadcasting is being properly received. The indicator 20 is not limited to this example.
It may be integrated with D18.

Each part of the receiving apparatus 1 has (B +)
A power supply 30 is supplied. The (B +) power supply 30 is supplied from a battery such as a mercury battery or a lithium ion battery, or a dry battery or a rechargeable battery. ON / OFF for the decoder 14 based on a control signal from the CPU 15
(B +) power supply 30 via switching element 21
Is supplied. Although the switching element 21 is shown as a transistor in this example, another element can be used as long as it is turned on / off by a predetermined control signal.

In the present invention, the CPU 15 determines whether the data of the third level supplied from the decoder 14, that is, the packet data, is valid data. Based on this determination, a control signal is output to the switching element 21 to control the supply of the (B +) power supplied to the decoder 14.

FIG. 7 schematically shows an example of the timing of this determination. The determination is made based on how many valid packets are supplied from the decoder 14 to the CPU 15 within a predetermined time. This determination is made based on an error detection flag supplied for each packet.

In this example, as shown in FIG.
The determination is made for 2 seconds, and no determination is made for the next 5 seconds.
This sequence is repeated. As described above, one frame of data is transmitted over about 5 seconds. One frame has 272 blocks and corresponds to 272 packets. Therefore, in 110 seconds, about 110 packets should be obtained.

Therefore, in this example, if more than 10 valid packets are supplied to the CPU 15 during two seconds during which the determination is being made, the data is determined to be valid data. Then, in the next 5 seconds, a control signal is issued from the CPU 15 to the switching element 21 so as to supply power to the decoder 14.

On the other hand, if the number of valid packets is less than or equal to 10 during the two seconds, it is determined that the data is not valid data. Then, in the next 5 seconds, the CPU is set so as not to supply power to the decoder 14.
15 outputs a control signal to the switching element 21.

As described above, according to the present invention, the decoder 14
Is an intermittent operation when the reception state is poor and valid data cannot be obtained more than a predetermined number. That is, of the seven-second cycle, the operation is performed only for two seconds for determining a valid packet, and the power supply is cut off and the operation is stopped for the remaining five seconds. If it is determined that a predetermined number or more of valid packets have been obtained in two seconds for the determination, power is supplied to the decoder 14 for the next five seconds, and decoding is continued.

Therefore, according to this embodiment,
In a situation where the reception state is poor, the decoder 14
/ 7 power is supplied, and the power supply (battery) of the receiver 1 can be saved.

In this embodiment, the lighting of the indicator 20 is controlled according to the result of this determination. As an example, the indicator 20 is turned on when, for example, 50 or more valid packets are obtained. The indicator 20 allows the user to know whether the reception state of the FM teletext is good.

By the way, when FM text multiplex broadcasting is not performed, no valid data can be obtained, and the decoder 14 operates intermittently. If the interval of the intermittent operation of the decoder 14 is too long, for example, it becomes impossible to acquire program-linked information transmitted by text multiplex broadcasting performed at a predetermined timing of FM broadcasting to supplement the program. . Therefore, in this embodiment,
The interval was 5 seconds. Of course, this is an example, and other time intervals may be used.

[0038]

As described above, according to the present invention, the number of valid packets in a received FM teletext broadcast is intermittently counted, and based on the counting result, the number of valid packets is supplied to a decoder of the FM teletext broadcast. ON / OFF of the power supply. Therefore, when receiving FM text multiplex broadcasting, moving to a place with bad radio wave conditions (for example, in a train or a building), or receiving FM broadcasting from a station where FM text multiplex broadcasting is not output For example, useless power supply can be stopped, and the duration of the battery can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a data structure of FM teletext broadcasting based on a DARC system.

FIG. 2 is a schematic diagram illustrating a data structure of FM teletext broadcasting based on the DARC system.

FIG. 3 is a schematic diagram illustrating a data structure of FM teletext broadcasting based on the DARC method.

FIG. 4 is a schematic diagram illustrating a data structure of FM teletext broadcasting based on the DARC method.

FIG. 5 is a schematic diagram for explaining a data structure of FM teletext broadcasting based on the DARC method.

FIG. 6 is a block diagram illustrating an example of a configuration of an FM teletext broadcast receiving apparatus according to an embodiment.

FIG. 7 is a schematic diagram illustrating an example of a timing of determining whether received data is valid data.

[Explanation of symbols]

11 ... tuner, 14 ... decoder, 15 ...
CPU, 16 ROM, 17 RAM, 18.
..LCD, 20 ... indicator, 21 ... switching element, 30 ... (B +) power supply

Claims (2)

[Claims] 1. A receiving apparatus for receiving a text broadcast superimposed on an FM broadcast, comprising: decoding means for decoding text broadcast data superimposed on the received FM broadcast; And a power control means for controlling the power of the decoding means based on a result of the determination by the determining means. 2. The receiving apparatus according to claim 1, wherein the display is turned on / off based on a result of the determination by the determining means.
A receiving device further comprising an indicator for performing F.