JP3485734B2 - FM multiplex signal receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention receives information data transmitted by being divided into a plurality of display unit data (page data) and a predetermined number of display unit data. The present invention relates to a digital signal receiving apparatus having a function of simultaneously outputting information,
The present invention relates to an M multiplex signal receiving device. 2. Description of the Related Art In recent years, as one of broadcasts that provide new services, FM multiplex broadcasts have been developed and put into practical use in which digital signals are multiplexed and transmitted in a vacant spectral region of a base band signal of FM stereo broadcasts. Is being promoted. [0003] FM multiplex broadcasting is a new medium that newly multiplexes a digital signal in a frequency band higher than the audio signal of the current FM stereo broadcast and broadcasts traffic information, character / graphic information, and the like. FM multiplex broadcasting is characterized by the fact that frequencies can be effectively used, broadcasting facilities can be easily realized, and that data can be received by a mobile unit, so that traffic information and the like can be easily transmitted to a mobile unit such as an automobile. [0004] Therefore, FM multiplex broadcasting is used as means for transmitting real-time congestion information or the like to an automobile equipped with a receiver or the like, or information necessary for a user having a handy type receiver is always available. As a means for providing an inexpensive transmission line that can be accessed anywhere, some practical applications have been started. [0005] Before describing the configuration of a conventional FM multiplex broadcast receiving apparatus, an outline of a data structure in FM multiplex broadcast will be described first. [0006] In FM multiplex broadcasting, factors that deteriorate the reception state include multipath interference and fading interference. In particular, in the case of mobile reception, its transmission characteristics are generally very poor. Even in such a case, it is desirable to have a system that can completely receive the data as soon as possible. However, in practice, there is a case where data transmitted by one reception cannot be completely received. In this case, it is premised that data to be retransmitted is received and data that cannot be received are supplemented. In the service area of FM multiplex broadcasting, FM
Although it is desirable that the service area is equivalent to the service area of stereo broadcasting, there are places in this service area where the average bit error rate exceeds 10 ^-2 . Therefore,
An error correction method and a frame configuration of a transmitted data structure are determined in consideration of such poor transmission path characteristics. In particular, an error caused by an extreme voltage drop due to fading interference is fatal, and error correction may not be possible. Therefore, by adjusting the unit data length of the transmitted data to the average burst length of the error caused by fading, if an error that cannot be corrected occurs, the unit retransmitted for each unit data It can be complemented by replacing it with data. Further, since the error correction effect is high, a product code in which two block codes are arranged orthogonally is used as an error correction method. Therefore, the data has a two-dimensional frame structure including an error correction code in both the vertical and horizontal directions. The transmission data has a data structure having a hierarchical structure with the data in one frame as a basic unit. [0010] As a specific example of the above description, a document (Proc. Of Vehicle Navigation & Information Sy
The FM multiplex broadcasting system disclosed in the Stems Conference (1994), A4-2 PP.111 to 116) will be described. FIG. 6 shows the specification of the hierarchical structure of data. In layer 1, transmission path characteristics are specified. In addition to the L + R signal and the LR signal, which are ordinary FM stereo broadcast signals, a multiplex signal is superimposed on the higher frequency side than the LR signal. This superposition method considers that the interference from the multiplex signal to the audio signal becomes remarkable when the audio modulation degree is small, and controls the level of the multiplex signal based on the modulation degree of the LR signal. Shi
ft Keying) method is adopted. The layer 2 defines a data frame structure including an error correction method. Each frame is composed of 272 blocks in the column direction, and has a 16-bit BIC at the beginning.
(Block Identification Code) is added.
Frame synchronization and block synchronization are performed based on C. Of the 272 parts in the column direction, 190 blocks are packets for transmitting data, and 82 blocks are parity packets for transmitting parity in the column direction. Each packet is composed of a 176-bit information section in the row direction, a 14-bit CRC (Cyclic Redundancy Code) as an error correction code, and an 82-bit parity section. That is,
At this stage, error correction is first performed on the transmission data using this one frame as a basic unit. Layer 3 defines the structure of a data packet. The data packet is BI out of each row in the frame.
It consists of 176 bits excluding C, CRC and parity. Further, this data packet is composed of a prefix and a data block. The prefix includes information for identifying the content of the data, and specifies, for example, which program content described below the data packet belongs to. Level 4 defines the structure of a data group. A data group is composed of one or a plurality of data blocks. That is, based on the information in the prefix in the data packet, the data packet numbers are arranged in the order of the data packet numbers from "0" to the data blocks with the information output flag in the prefix. This data group also includes a CRC, which is an error correction code, and the transmission data is also subjected to error correction in this layer. One data group corresponds to one display unit, that is, one page of data. The layer 5 defines the structure of a group of information data transmitted by FM multiplex broadcasting, that is, program data. FIG. 7 shows the structure of the program data. A program of character and graphic information is composed of a plurality of data groups, and the first data group is composed of encoded information relating to the entire program such as a program number and the total number of pages as program management data. Following the program management data, there are a plurality of page data, and the data for each page is encoded. The program data and the page data are composed of a data header section and a data unit group. The data unit group includes a plurality of data units divided for each encoding, such as a character data section and a photographic graphic data section. That is, in the above data structure, the program data forms a group of data indicating a group of information on the receiving side. For example, if it is traffic information, the program information indicates the congestion status at each junction of a specific route (such as an expressway)
If it is a weather forecast, it indicates weather forecast information in a specific area. FIG. 8 is a schematic block diagram showing the configuration of a conventional FM multiplex broadcast receiver 10. As shown in FIG. In FIG. 8, the FM multiplex broadcast signal received by the antenna 12 and the tuner 14 is detected by the detection circuit 16 and further applied to the LMSK demodulation circuit 20 via the band pass filter 18. The LMSK demodulation circuit 20 demodulates the data of the FM multiplex broadcast signal which has been subjected to the LMSK modulation, and extracts the FM multiplex signal. The demodulated data signal is supplied to the synchronous reproduction circuit 22 at the level B as described in the hierarchy 2 in FIG.
Frame synchronization and block synchronization are performed based on the IC. The synchronized data signal is error-corrected in the error correction circuit 24 based on the parity code and the CRC. Therefore, the FM multiplexed broadcast packet data (having the configuration shown in layer 3 in FIG. 6) that has been normally received or error corrected has been output from this error correction circuit 24. A central processing unit 40 (hereinafter referred to as a CPU) extracts data blocks, reconstructs data blocks, corrects errors at a data group stage, and converts program data into input packet data. After the reconstruction, the program data is output to the display device 42. The display device 42 outputs the input program data as graphics or characters. Here, a liquid crystal screen having a display area of one page, that is, 248 × 60 dots (corresponding to 15.5 characters × 2.5 lines in Japanese display) is used as the display device 42. FIG. 9 shows a configuration in which the tuner 14 to the synchronous reproduction circuit 22 of the FM multiplex broadcast receiving apparatus shown in FIG. 8 are constituted by an IC card 21 so that characters received by the notebook type personal computer 120 are displayed. It is a figure showing an example. In FIG. 9, the IC card 21 is detachable from the personal computer 120. In this example, the tuning of the reception frequency is performed by auto-tuning according to a command from the personal computer 120. [0021] As shown in FIG.
Since the receiving unit built in the C card 21 and the signal processing unit of the personal computer 120 are separated, the personal computer 120
Cannot know the receiving state of the receiving unit. In order for the personal computer 120 to know the reception status of the card 21, the personal computer 1
20 must issue a command and have the card return status information. However, in this method, the personal computer 120 cannot obtain the latest status information on the receiving side. Further, the receiving side needs to frequently notify the personal computer 120 of the status and the packet data of the FM multiplex broadcast. This is because the personal computer 120 needs to extract data blocks, reconstruct data groups, correct errors at the data group stage, and reconstruct program data from the given packet data.
However, since the status and the FM multiplexed packet data have different data structures, the personal computer 120 needs a means for distinguishing these data and a means for processing the data. Therefore, a main object of the present invention is to provide an FM multiplex signal receiving apparatus in which a receiving section and a signal processing section are separated so that the signal processing section can always receive a signal indicating the reception state of the receiving section. To provide an FM multiplex signal receiving apparatus. According to the present invention, in an FM multiplex communication system in which each of a plurality of information data to be transmitted is divided into a plurality of display unit data and transmitted, each of the display unit data corresponds to An FM multiplex signal receiving apparatus for receiving transmission data including number data indicating a position in information data to be transmitted, a demodulation means for receiving a carrier transmitting the data of the display unit by FM multiplex transmission and performing FM demodulation; Packet data generating means for receiving the output of the demodulating means, extracting an FM multiplex signal and generating the data as packet data, and detecting means for detecting whether or not packet data to be transferred has been generated by the packet data generating means. If the detecting means detects that there is packet data to be transferred, the packet data to be transferred is stored, while the packet data to be transferred is stored. Storage means for storing fill data in place of data to be transferred when it is detected that there is no packet data; flag means for displaying the presence or absence of packet data in the detection means; Signal processing means for reading out the packet data and reconstructing the display data, wherein the signal processing means is configured to be separable from the demodulation means, the packet data generation means, the detection means, the storage means, and the flag means. And the signal processing means reads packet data from the storage means according to the display of the flag means. FIG. 1 is a schematic block diagram showing a configuration of an FM multiplex broadcast receiving apparatus according to an embodiment of the present invention. In FIG. 1, an FM multiplex broadcast receiving apparatus 100 includes:
An antenna 12 for receiving an FM radio wave, an FM tuner unit 14 for receiving the output of the antenna 12 for FM demodulation, receiving an output of the FM tuner unit 14, extracting an FM multiplexed signal, correcting an error, and outputting a corresponding digital signal And a personal computer 120 that receives the digital signal to form display unit data (page data) and displays corresponding characters and the like. The difference from the configuration of the conventional FM multiplex broadcast receiving apparatus 10 shown in FIG. 8 is that the FM multiplex decoding section 15 extracts the FM multiplex signal from the signal FM-modulated by the FM tuner section 14 and outputs the packet data. The digital signal output as
0 is received, the packet data is reconstructed into program data and displayed. That is, the FM multiplex broadcast signal received by the antenna 12 is
In the M demodulation circuit 2, the phase locked loop circuit 4
The signal is synchronously detected by a local oscillation wave output from a PLL circuit (hereinafter, referred to as a PLL circuit), and output to the FM multiplex decoding unit 15 via the buffer 6. The FM multiplex decoder 15 receives the signal demodulated by the FM through the buffer circuit 8, extracts a signal component in a predetermined frequency region by the band-pass filter 18, performs LMSK demodulation in the demodulation LSI 20, and extracts the FM multiplex signal. I do. The CPU 26 receives the output of the demodulation LSI 20, performs block synchronization and error correction of the received data, and outputs the packet data as packet data. At this time, if there is uncorrectable packet data, the data is deleted by the CPU 26, and only data necessary for display is selected and output. The RAM 28 operates as a buffer for receiving data from the CPU 26 and outputting data to the interface 30. When the address decoder 32 detects that the CPU 26 has accessed the personal computer 120, it outputs data from the interface 30. The controller 34 normally has the interface 30
Receiving the output data from the personal computer 1
20 is output. However, when the apparatus is started up, initial settings between the interfaces are performed based on data stored in the ROM 36. The personal computer 120 receives the packet data output from the FM multiplex decoder section 15 via the interface 38. The CPU 40 receives the output data from the interface 38, that is, the packet data, extracts a data block from the data packet in accordance with the hierarchical structure shown in FIG. 8, reconstructs a data group from the data block, and performs error correction on the data block. Perform Further, the CPU 40 extracts a data header and a data unit group corresponding to the base data from the data group data in the data group, and reconstructs the program data. Further, the personal computer 120
An auto scan command is given to the M multiplex decoding unit 15. When an auto scan instruction is given from the personal computer 120, the CPU 26 of the FM multiplex decoding unit 15 controls the FM tuner unit 14 to perform an auto scan operation. The personal computer 1
Reference numeral 20 includes a display unit 42. The display unit 42 uses a liquid crystal flat panel display or the like, and its display area has a resolution of 640 × 400 dots or more. FIG. 2 is a block diagram of the controller shown in FIG. 2, the controller 34 includes a data / status register 35, a command register 37, and a flag register 39. The data / status register 35 is composed of a FIFO memory, and stores data and status given from the card 21 to the personal computer 120. The command register 37 stores a command given from the personal computer 120. Flag register 39
Activates the D bit when data or status is stored in the data / status register 35, and activates the C bit when a command is stored in the command register 37. FIG. 3 is a flowchart for explaining the processing operation on the card side, FIG. 4 is a flowchart for explaining the processing operation on the personal computer side, and FIG. 5 is a diagram showing an example of the data format. Next, the operation of the embodiment of the present invention will be described with reference to FIGS. C of personal computer 120
The PU 40 determines whether or not there is a command to be transmitted according to the card 21 according to the main routine of FIG. This command is stored in the command register 37 of the controller 34, and at the same time, the C bit of the flag register 39 is activated. The card 21 determines in the flowchart shown in FIG. 3 that the C bit has become active, and fetches the command stored in the command register 37 for processing. Then, the response value is updated. Further, the CPU 26 of the card 21 determines whether there is any data, response, or status to be transferred when the C bit is not active,
If so, it is determined whether or not there is transfer data. If there is no transfer data, the response and status are set in the data / status register 35 together with the fill data. If there is transfer data, the data, response and status are set in the data / status register 35 in the manner shown in FIG. 5, and the D bit of the flag register 39 is activated. The CPU 40 of the personal computer 120 determines that the D bit of the flag register 39 has become active, reads the data from the data / status register 35, sets the response flag in the CPU 40, and sets the response flag in FIG. Return to the main routine. In the main routine, it is determined that the response flag has become active, and the response flag is made inactive. As described above, in this embodiment, the CPU 26 of the card 21 transmits the response and the status to the personal computer 120 irrespective of the presence or absence of the data to be transferred, and furthermore, transmits the response and the status in the data format shown in FIG. Therefore, the latest status information can be obtained on the personal computer 120 side, and it is not necessary to provide a means for distinguishing between status and data, and the hardware configuration can be simplified and the processing can be simplified. As described above, according to the present invention, a signal indicating the reception state is output to the signal processing means side in the same format regardless of the presence or absence of data. In such a case, the latest information can always be obtained, and it is not necessary to provide a special means for distinguishing from data.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of an FM multiplex signal receiving apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a controller shown in FIG. 1; FIG. 3 is a flowchart showing a processing operation on the IC card side. FIG. 4 is a flowchart showing a processing operation on the personal computer 120 side. FIG. 5 is a diagram showing a data format used in the embodiment of the present invention. FIG. 6 is a diagram showing FM multiplex broadcasting specifications. FIG. 7 is a schematic diagram showing a configuration of program data. FIG. 8 is a schematic block diagram showing a configuration of a conventional FM multiplex broadcast receiving apparatus. 9 is a diagram showing an example in which the tuner section of the FM multiplex broadcast receiving apparatus shown in FIG. 8 is configured by an IC card and characters are displayed on a notebook personal computer. [Description of Signs] 2 FM demodulation circuit 4 PLL circuits 6 and 8 Buffer circuit 12 Antenna 18 Band pass filter 20 LMSK demodulation circuit 26, 40 CPU 28 RAM 30, 38 Interface 32 Address decoder 34 Controller 35 Data / status register 37 Command register 39 flag register 42 display unit 44 memory 100 FM multiplex broadcast receiving device

Continued on the front page (72) Inventor Morihiko Sumino 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hiroyuki Tachibana 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo (72) Inventor Takeharu Matsui 2-5-1, Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-8-191255 (JP, A) JP-A-7- 38488 (JP, A) JP-A-3-209947 (JP, A) JP-A-9-270798 (JP, A) JP-A-6-119262 (JP, A) JP-A-9-135224 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H04J 1/00 H04B 1/16

Claims (1)

(57) [Claim 1] In an FM multiplex communication system in which each of a plurality of information data to be transmitted is divided into a plurality of display unit data and transmitted, each display unit data corresponds to the corresponding information. An FM multiplex signal receiving apparatus for receiving transmission data including number data indicating a position in data, a demodulation means for receiving a carrier transmitting the data of the display unit by FM multiplex transmission and performing FM demodulation; extracting an FM multiplex signal in response to an output means, Pas
Packet data generating means for generating a packet data
The packet data to be transferred by the packet data generating means.
Detecting means for detecting whether data has been generated, and detecting the packet data to be transferred by the detecting means.
If issued, store the packet data to be transferred,
On the other hand, when it is detected that there is no packet data to be transferred,
In this case, fill data is stored instead of data to be transferred.
Storage means for storing the packet data in the detection means.
Reading and grayed unit, the packet data stored in said storage means
Te, a signal processing means for reconstructing the display data, said signal processing means, the demodulating means, the packet data
Data generating means, the detecting means, the storing means, and the flag means, and the signal processing means is configured to operate in accordance with the display of the flag means.
Reading packet data from the storage means.
An FM multiplex signal receiving device.