JPH08321814A - Receiver - Google Patents

Abstract

PURPOSE: To automatically select a teletext broadcasting station in an FM teletext broadcasting receiver. CONSTITUTION: The reception circuits 11-14 of a synthesizer system, which receive teletext broadcasting, a display element 50 displaying a character in accordance with character data received by the reception circuits 11-14 and a scan key 62A are provided. When the scan key 62A is operated, a reception band is scanned at prescribed frequency steps. At the time of scanning, whether teletext broadcasting can be received or not is judged in respective frequencies. When teletext broadcasting can be received, scanning is stopped at the frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for receiving teletext broadcasting.

[0002]

2. Description of the Related Art In FM broadcasting, called "FM character multiplex broadcasting", it has been realized that data such as character information is multiplexed and transmitted together with a program of an original audio broadcasting. Then, the FM character multiplex broadcast is received, and L
FM receivers capable of displaying character information on a display element such as a CD (liquid crystal display element) have been commercially available.

This FM character multiplex broadcasting is capable of mobile reception and is called the DARC system. The standard for multiplexing digital data such as character information is that the subcarrier frequency is 76 kHz, the transmission rate is 16 kbit / sec, and the modulation is performed. The method is LMSK, and the error correction method is a product code based on the (272,190) shortened difference set cyclic code.

There are distinction between levels 1, 2, and 3 as a program service such as character information. All of these are for presenting (displaying) character information etc. by dot display, but Level 1 is a service for receivers that can display 15.5 characters × 2.5 lines including the header part,
Information is text. Level 2 is a service for a receiver capable of displaying 15.5 characters x 8.5 lines including a header part, and the information is characters and figures. Level 3 is a traffic information service for a receiver that can display a detailed map on a CD-ROM, that is, a navigation system.

As the level 1 program service, news, weather forecast, traffic information, entertainment and main complementary programs are considered. In this case, entertainment includes fortune telling, listener message boards,
It provides information such as quizzes and town information.

[0006] Further, the main supplementary program is, for example, when the original audio broadcasting program is a music program, the supplementary information of the program such as the music title, performer name, telephone number / FAX number at the time of request, and the like. It is provided. In the following, main complementary programs are referred to as “program information” or “program-linked”.

Further, as a program service other than the above,
"Urgent information" provided at any time when there is an urgent need
Is also considered.

FIG. 4 shows a frame structure of an LMSK signal multiplexed in the above FM character multiplex broadcasting. One frame of this LMSK signal is composed of 272 blocks,
Each block has 288 bits.

Further, one frame is divided into blocks of 190 data packets and blocks of 82 vertical parity packets, and the blocks of vertical parity packets are distributed and transmitted.

A 16-bit BIC (block identification code) is added to the beginning of each block. However,
Four types of BIC are used, which distinguish each parity packet and identify the beginning of the frame.

The block of the data packet is BI
It has a 176-bit data packet following C, followed by a 14-bit CRC code, followed by 82
It has a horizontal parity check code of bits.

In this case, the CRC code is added to detect the residual error after the error correction by the product code. The block of vertical parity packets is assumed to have a vertical parity packet of 272 bits following the BIC.

Further, each data packet is, as shown in FIG. 5, a 32-bit prefix followed by 144 bits.
And a data block of bits.

As shown in FIG. 6, this prefix is composed of a service identification code, a decoding identification flag, an information end flag, an update flag, a program number, a page number, a data link code, and a data packet number.

The service identification code is 4 bits,
The program content is identified. And level 1
Regarding, "1" is general information for sequential reception processing,
“2” is general information for recording and reception processing, and “4” is traffic information.

In this case, the sequential reception process is a mode in which the decoding process of the presentation is started as soon as the first data packet of the program data or page data arrives at the receiver, and the recording reception process is the program data or Receives and records all page data and CRs for each data group
In this mode, the presented decoding process is started only after the error correction process using the C code is performed.

Then, in the case of a program for which it is necessary to set the timing of presentation on the receiving side on the transmitting side, or for a program which cannot be presented in time if the decoding process is started after the final packet of the data group is obtained, It is a reception process.

The decoding identification flag is 1 bit and is set to "1" when the error correction circuit of the receiver outputs the data by decoding only in the horizontal direction, and the data is decoded after the horizontal and vertical directions are combined. When outputting, it is set to "0".

In the successive reception process, when the decoding identification flag is "0", the receiver receives the first BIC of each data packet and receives the first BIC of the data packet 302 packets after. At this point, it is specified to perform a decoding process for presentation of each data packet.

The information end flag is 1 bit and is set to "1" when the data group to be transmitted with a certain data group number ends, and "0" otherwise.
It is said. Furthermore, the update flag is 2 bits and is incremented by 1 each time the data group is updated. The program number is 8 bits and the page number is 6 bits, and a data group number is formed by both.

Further, since the data link code is 2 bits and the data which should belong to one data group is a large amount of data such that the number of packets exceeds the maximum value of the data packet number, the maximum is possible. It is a code for linking in the order of 0 → 1 → 2 → 3 between the data groups when divided into four data groups and transmitted by the same data group number with different data link codes.

The data packet number excluding the data link code is 8 bits and is assigned in order from "0".

Further, the program numbers are set from 0 to 255, the "total table of contents" is assigned to "0", and "254" is assigned to the main complementary program (program information or program interlocking) as emergency information. “255” is assigned to each.

The page numbers are from 1 to 62,
That is, one program has a maximum of 62 pages. One page corresponds to one data group, and one data group is composed of one or a plurality of data blocks.

At level 1, one page is generally in the display format of 15.5 characters × 2.5 lines,
The display format can be 5.5 characters x 8.5 lines. Also,
In this case, the character data specifies the character to be displayed by the JIS code.

As described above and as shown in FIG. 7, the receiver corresponding to the level 1 is, for example, the LCD 1 having the display screen 1a capable of displaying 15.5 characters × 2.5 lines. . However, the lower left 15 characters x 2 lines portion 1b of the display screen 1a is set as the body text display area, and the upper 0.5 lines and the right half character portion 1c with hatching are set as the header sentence display area. It

The receiver receives the LMSK signal together with the stereo composite signal, decodes the character data from the LMSK signal, and writes the decoded character data in the buffer memory.

Further, the receiver or the remote control transmitter for remotely controlling the receiver is provided with a "general table of contents" key, and by operating this key, the receiver displays as shown in FIG. 8 (A). A general table of contents (main menu) is presented on the screen 1a. However, in FIG. 8A, the total table of contents is displayed over a plurality of pages or in a display format of 8.5 lines, and the first one page or the first 2.5 lines of them is displayed.

Further, the receiver or remote control transmitter is
Further, a "page (screen) advance" key is provided. By operating this key, as shown in FIG. 8B, the display screen 1a displays the next page, or a page with a display format of 8.5 lines. The next two lines of are displayed.

Then, when the user selects and decides the number of the item to be viewed from the total contents, the contents of the selected and decided item are further presented. For example, when the user selects “3. Weather forecast” from the total table of contents, the table of contents such as “1. Today's weather” and “2. Tomorrow's weather” is presented as shown in FIG. .

Further, when the user selects and determines the number of the item to be viewed from the table of contents, the first page of the selected and determined item is presented. For example, when the user selects “1. Today's weather” from the above table of contents, as shown in FIG. 10, specific character information on “Today's weather” is presented.

[0032]

By the way, when moving by an automobile or the like, the frequency of the FM station at the destination may not be known. In addition, even if the frequency is known, not all FM stations are performing character multiplex broadcasting. Furthermore, even an FM station that is performing character multiplex broadcasting may suspend character multiplex broadcasting depending on the time of day.

Therefore, when receiving a character broadcast (when viewing a character broadcast), (1) the FM station is selected. (2) Wait for a while watching whether the characters are displayed. (3) If no characters are displayed, return to item (1). It must be repeated.

However, the operations like the items (1) to (3) are troublesome. Furthermore, if you want to know traffic information while driving a car, you may not be able to perform the operations described in (1) to (3).

The present invention is intended to solve such a problem.

[0036]

Therefore, in the present invention, a synthesizer type receiving circuit for receiving a character multiplex broadcast, a display element for displaying characters according to the character data received by the receiving circuit, When the scan key is operated and the scan key is operated, the reception band is scanned in predetermined frequency steps, and it is determined whether the character multiplex broadcast can be received at each frequency at the time of this scan. When the character multiplex broadcasting can be received, the receiver is designed to stop the scanning at the frequency.

[0037]

When the key is operated once, the scanning of the reception band is started, the scanning is stopped at the station for carrying out the character multiplex broadcasting, and thereafter the channel is selected for that station.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a signal system when the present invention is applied to an on-vehicle FM receiver. That is, the FM signal received by the antenna 11 is supplied to the tuner circuit 12 of the synthesizer system to select a broadcasting station having a target frequency, and the FM signal is converted into an intermediate frequency signal. Signal is intermediate frequency amplifier 13
Is supplied to the FM demodulation circuit 14 through.

In this way, from the demodulation circuit 14, the summed signal (L + R) of the stereo left and right channel audio signals L and R, the DSB signal balanced-modulated by the difference signal (LR), and the pilot signal. And the above-mentioned F
A frequency-multiplexed signal with the LMSK signal in M-character multiplex broadcasting is taken out.

Then, this frequency-multiplexed signal is supplied to the stereo demodulation circuit 15, and the added signal (L + R) and D are added.
Audio signals L and R are demodulated from the SB signal, and these signals L and R are supplied to left and right channel speakers 17L and 17R through amplifiers 16L and 16R.

Further, the FM receiver is provided with a microcomputer 20 for selecting a channel in the tuner circuit 12 and displaying characters by FM character multiplex broadcasting.

That is, this microcomputer 20
Is a CPU 21 for executing the program, and a ROM
22, a RAM 23 for a work area, and a RAM 24 for a reception buffer of data of FM character multiplex broadcasting. In this case, various routines and data for displaying a predetermined character string (sentence) are written in the ROM 22, and a tuning routine 100 shown in FIG. 3, for example, is provided as a part of the routine. .

The memories 22 to 24 are connected to the CPU 21 through the system bus 29, and
The bus 29 has interface circuits (ports) 25 to
28 is connected.

Then, the interface circuit 25 supplies the tuner circuit 12 with data for channel selection, and the channel selection is executed. In addition, the demodulated signal from the demodulation circuit 14
The data in the FM character multiplex broadcast is decoded and taken out from the LMSK signal supplied to the decoder circuit 41, and this data is read through the interface circuit 26 to R
Written in the AM 24, the data in the RAM 24 is constantly updated with the latest data.

The interface circuit 27 is also connected to various operation keys 42 composed of non-lock type push switches, and the key output thereof is taken into the microcomputer 20. Thus, the key 42
If you press any of the keys, the pressed key will
The determination is made by U21, and the process corresponding to the pressed key is executed.

However, when the FM receiver is mounted on a vehicle,
Since the operation panel is narrow and a large number of operation keys cannot be arranged, in this example, the keys 42 are only the keys with high operation frequency and the important keys, and the other operations are remote control (remote operation). ).

Therefore, the receiving circuit 43 of the remote controller is also connected to the interface circuit 27. In this example, the remote controller is of the infrared type, and the receiving circuit 43 includes a light receiving element for receiving infrared rays from the transmitter 60 of the remote controller and a decoder circuit for decoding the remote control signal from this light receiving element. Have and.

Further, the remote controller transmitter 60 is also provided with various operation keys 62 (62A to 62N) constituted by non-lock type push switches. Although a part of the key 62 has the same function as the key 42, when any key of the keys 62 is pressed, data corresponding to the pressed key is formed, and the data is converted into infrared rays to be converted into the FM receiver. Sent to.

In the FM receiver, the transmitter 6
When the infrared ray transmitted from 0 is received by the receiving circuit 43, the original data is taken out and this data is supplied to the interface circuit 27. Thus, the key 42
When the key 62 is pressed, the processing corresponding to the pressed key is performed by the microcomputer 20 as in the case of pressing.
Is executed by In the following, the transmitter 60
The operation of each part will be described depending on the case where the key 62 of is used.

A muting control signal is supplied from the interface circuit 28 to the amplifiers 16L and 16R.

Further, the bus 29 is connected with a font ROM (character generator) 31 having font data for converting the character code sent by the FM character multiplex broadcasting into display data, and a display memory. 32 and a display controller 33 are connected, and an LCD 50, for example, is connected to the controller 33 as a display element.

In this case, the LCD 50 is constructed in this example in the same manner as the LCD 1 described above, and is 15.5 characters × 2.
It has a display capacity of 5 lines. The memory 32 is of a bitmap type corresponding to the dot display type of the LCD 50 and has a capacity of one screen.

Then, the character code held in the RAM 24 is read by the CPU 21, the read character code is converted into display data using the font data of the ROM 31, and this display data is stored in the memory 3.
Written to 2. At this time, the controller 33
Thus, the display data in the memory 32 is repeatedly read, converted into a display signal, and supplied to the LCD 50. Therefore, in the LCD 50, the CPU 21
The characters of the character code read from M24 are displayed.

FIG. 2 shows an example of the tuner circuit 12.
The tuner circuit 12 is of a synthesizer type, and the received signal from the antenna 11 is supplied to an electronic tuning type antenna tuning circuit 121 to extract a broadcast wave signal SRX of a target frequency fRX. Signal S
RX is supplied to the mixer circuit 123 through the high frequency amplifier 122.

Further, the frequency fLO is, for example, fLO = fRX-fIF [kHz] (4) fIF is an intermediate frequency from the VCO 81, and the oscillation signal SLO of fIF = 10.7 MHz is taken out. Is supplied as a local oscillation signal to the mixer circuit 123, and the signal SRX is frequency-converted into an intermediate frequency signal SIF (intermediate frequency fIF). Then, the intermediate frequency signal SIF is supplied to the intermediate frequency amplifier 13 as described above.

At this time, the VCO 81 has the circuit 82
˜85 together form a PLL 124. That is, the signal SLO from the VCO 81 is supplied to the variable frequency dividing circuit 82 and divided into a frequency of 1 / N. This frequency divided signal is supplied to the phase comparison circuit 83 and the oscillation circuit 84.
An oscillation signal having a reference frequency, for example, a frequency of 100 kHz, is extracted from the VCO 81, and the oscillation signal is supplied to the comparison circuit 83.
Is supplied as its control voltage. In addition, the filter 85
Output voltage is supplied to the tuning circuit 121 as a tuning voltage.

Therefore, in the steady state, the frequency-divided signal from the frequency-dividing circuit 82 and the oscillating signal of the oscillating circuit 84 have the same frequency. Therefore, the frequency fLO of the oscillating signal SLO at this time is fLO = N × 0.1 [MHz] (5), and from the expressions (4) and (5), fRX = fLO + fIF = N × 0.1 + 10.7 [MHz].

Therefore, if the division ratio N is changed by "1" between 653 and 793, the local oscillation frequency fLO
However, the frequency fRX varies between 65.3 MHz and 79.3 MHz in 100 kHz frequency steps.
That is, the frequency band of 76 MHz to 90 MHz is changed in 100 kHz frequency steps and in accordance with the frequency division ratio N.

In such a structure, when the scan key 62A of the keys 62 (or 42) is pressed, the routine 100 is executed, and the FM station which is performing the character multiplex broadcasting is automatically selected.

That is, when the scan key 62A is pressed,
The processing of the CPU 21 starts from step 101 of the routine 100, then in step 102, the current frequency division ratio N in the frequency divider circuit 82 is saved in the RAM 23, and then in step 103, the amplifier 16L, through the interface circuit 28, Muting of 16R is turned on, and then in step 104,
The frequency division ratio N is set to the minimum value 653.

Next, at step 111, the division ratio N
(N = 653 in this case) is the interface circuit 25
Is set in the frequency dividing circuit 83 through the tuner circuit 12
Is selected to a frequency fRX corresponding to the frequency division ratio N (in this case, the lowest frequency is 76 MHz).

Subsequently, the process proceeds to step 112, in which the timer for setting the determination period of whether the received FM station is performing the character multiplex broadcasting is set, and then in step 113, the present time is set. It is determined whether or not the character multiplex broadcasting is being performed at the selected frequency fRX. This determination is made, for example, based on whether or not the horizontal error correction in the frame and the CRC in the data packet can receive a packet recognized as normal.

If it is determined that the character multiplex broadcasting is not being performed, the process proceeds from step 113 to step 114. In this step 114, the timer set in step 112 has a predetermined time, for example, 10 seconds.
It is checked whether or not the second has been exceeded. If not, the process returns from step 114 to step 113.

Therefore, by the steps 113 and 114, for example, the frequency fRX currently selected for 10 seconds is selected.
Then, it is determined whether or not the character multiplex broadcasting is being performed.

When it is determined that the character multiplex broadcasting is not performed even after 10 seconds, the timer set in step 112 expires. Then, the process proceeds from step 114 to step 115. In this step 115, it is checked whether the current division ratio N is the maximum value, that is, whether the current reception frequency fRX is the highest frequency of the reception band.

When the frequency division ratio N has not reached the maximum value, the process proceeds from step 115 to step 116, where the frequency division ratio N is "1".
Is incremented only, and then the process proceeds to step 11
Return to 1.

Therefore, thereafter, steps 111 to 11 are executed.
6 is repeated, and the tuning frequency fRX of the tuner circuit 12
Becomes higher by 100 kHz corresponding to the frequency division ratio N.
That is, the reception band is scanned from the lowest frequency.

Then, when a character multiplex broadcast is received at a certain reception frequency fRX, this is detected in step 113, and the process proceeds from step 113 to step 121.
In step 121, the amplifier 16L,
The muting of 16R is turned off, and then the routine 100 is ended in step 122.

Therefore, thereafter, the tuning state of the FM station which is determined to be the character multiplex broadcasting in step 113 continues, so that the LCD 50 displays the program of the character multiplex broadcasting by the FM station.

When the character multiplex broadcasting cannot be received even if the scanning proceeds to the highest frequency of the reception band,
At this time, the frequency division ratio N becomes the maximum value 793, and this is detected in step 115.

Then, the process proceeds from step 115 to step 131, and in this step 131, the ROM
The character code of the character string prepared in 22 is the ROM 31
Is converted into display data by the font data of, and this display data is supplied to the memory 32.
In 0, for example, a character string "There is no teletext" is displayed.

Subsequently, at step 132, when the frequency dividing ratio N saved in the RAM 23 at step 102 is set in the frequency dividing circuit 82 and the routine 100 starts, that is, when the scan key 62A is pressed.
The FM station that was RX was selected, and then step 133
At step 134, the muting of the amplifiers 16L and 16R is turned off, and then the routine 100 is ended at step 134.

In this way, according to this FM receiver, when the scan key 62A is pressed, the FM station which is performing the character multiplex broadcasting is automatically searched and selected. Therefore, when moving by car, even if you do not know the frequency of the FM station at the destination, or at all FM stations,
Even if the character multiplex broadcasting is not performed, or even if the character multiplex broadcasting is suspended depending on the time period, if the character multiplex broadcasting is performed, the broadcast can be viewed. Moreover, for that reason, troublesome operation is unnecessary.

[0074]

According to the present invention, when a predetermined key is operated, an FM station which is performing character multiplex broadcasting is automatically searched and selected. Therefore, when moving by car, even if the frequency of the FM station at the moving destination is unknown, if the character multiplex broadcasting is performed, the character broadcasting can be viewed. Moreover, for that reason, troublesome operation is unnecessary.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of the present invention.

FIG. 2 is a system diagram showing an example of a part of the present invention.

FIG. 3 is a flowchart showing an example of the present invention.

FIG. 4 is a diagram for explaining a signal format.

FIG. 5 is a diagram for explaining a signal format.

FIG. 6 is a diagram for explaining a signal format.

FIG. 7 is a diagram for explaining a display screen.

FIG. 8 is a diagram for explaining a display screen.

FIG. 9 is a diagram for explaining a display screen.

FIG. 10 is a diagram for explaining a display screen.

[Explanation of symbols]

 12 tuner circuit 13 intermediate frequency amplifier 14 FM demodulation circuit 15 stereo demodulation circuit 20 microcomputer 21 CPU 22 ROM 23 RAM (for work area) 24 RAM (for reception buffer) 31 font ROM (character generator) 32 memory (for display) 33 Display controller 41 Decoder circuit 42 Operation key 43 Reception circuit (for remote control) 44 Forming circuit (for beep sound signal) 50 Display element 60 Transmitter (for remote control) 62 Operation key 100 Tuning routine

Claims (3)

[Claims] 1. A synthesizer type receiving circuit for receiving a character multiplex broadcast, a display element for displaying characters according to character data received by the receiving circuit, and a scan key. The scan key is operated. In this case, the reception band is scanned at a predetermined frequency step, and it is determined whether or not the character multiplex broadcast can be received at each frequency at the time of this scanning. A receiver designed to stop the above scanning at a frequency. 2. The receiver according to claim 1, wherein the determination is executed for each frequency for a predetermined period, and when it is determined that the character multiplex broadcasting is performed within this period, the scan of the scan is performed. A receiver designed to stop. 3. The receiver according to claim 1, wherein the determination is made by a data error correction function in the character multiplex broadcasting.