JP2008177960A - Fm transmitter and electronic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an FM transmitter capable of easily performing channel selection and frequency tuning, and electronic equipment using the same. <P>SOLUTION: A data generator 12 sets a prescribed value to a data item on which a reception side bases channel selection, and generates data in RDS/RBDS format. A frequency modulator 24 frequency-modulates the data in RDS/RBDS format generated by the generator 12 and outputs the frequency-modulated data. A data item may be a program type. The program type is set irrelevantly to the kind of data transmitted from an FM transmitter 100. A receiver selects a channel in a state wherein the value of the program type is set to the prescribed value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an FM transmitter that supports RDS (Radio Data System) or RBDS (Radio Broadcast Data System).

  In recent years, European FM radio stations and US radio broadcast stations have transmitted additional information such as text as European RDS (Radio Data System) or US RBDS (Radio Broadcast Data System) information. . By using RDS / RBDS, various information such as the name of a broadcast station currently received and the genre of music can be used in a car radio receiver (Patent Documents 1 and 2).

  On the other hand, FM transmitters that convert an audio signal into a stereo composite signal, perform frequency modulation using a frequency modulator, and output the same are known (Patent Documents 3 to 5). If an FM transmitter is used, an audio signal can be transmitted without going through a wiring such as an RCA cable. Therefore, the FM transmitter can be used for transmission of a signal between a car audio CD changer and a head unit. In recent years, hard disk audio devices, memory audio devices, and mobile phone terminals with music playback functions have been remarkably widespread. Music data stored in such small electronic devices can be played from speakers such as stationary audio components. FM transmitters are also used for such applications.

JP-A-8-256135 JP-A-8-191232 Japanese Patent Laid-Open No. 9-069729 JP-A-10-013370 JP-A-9-312588 NATIONAL RADIO SYSTEMS COMMITTEE, “UNITED STATES RBDS STANDARD”, USA, April 9, 1998

  Here, conventionally, the user manually matches the transmission frequency of the FM transmitter and the reception frequency of the radio tuner (receiver). In this case, it takes time for the user to recognize the frequency on the FM transmitter side and set the frequency on the radio tuner side. Further, when the transmission frequency of the FM transmitter overlaps with other broadcasting stations, it is necessary to reset the transmission frequency of the FM transmitter and the reception frequency of the radio tuner.

  The present invention has been made in view of these problems, and a comprehensive object thereof is to provide an FM transmitter that can easily perform tuning and frequency tuning.

  One embodiment of the present invention relates to an FM transmitter capable of transmitting a signal conforming to an RDS (Radio Data System) or RBDS (Radio Broadcast Data System) format. This FM transmitter sets a predetermined value in a data item that can be a channel selection reference on the receiving side, generates a data in RDS / RBDS format, and an RDS generated by the data generator A frequency modulator that frequency-modulates and outputs data in the / RBDS format.

“Data item that can be used as a channel selection criterion” refers to data used for tuning search. As a technical premise, when a receiver sets a value in a data item, it has that value as a data item. The frequency can be automatically extracted.
According to this aspect, when tuning the frequency of the receiver with the transmission frequency, instead of inputting the frequency, if a predetermined value is input to the data item, the receiver automatically sets a channel having the predetermined value to the data item. Automatic tuning can be selected.

  The data item may be a program type. For example, when a predetermined value “news” is set as the program type, the FM transmitter can be automatically selected if the program type is set to “news” in the receiver.

  The program type may be set regardless of the type of data transmitted from the FM transmitter. That is, even when the predetermined value “news” is set, the content of the audio signal transmitted from the FM transmitter does not need to be news and may be arbitrary. This is different from broadcasting from a broadcasting station.

  The data item may be a music / voice (music / speech) code. The music / voice code may be set regardless of the type of data transmitted from the FM transmitter.

  The data generation unit may set a predetermined value in accordance with user designation. It is more convenient if the user can change the value of the data item on the receiver side and the value of the data item on the FM transmitter side.

  The FM transmitter may be integrated on a single semiconductor substrate. “Integrated integration” includes the case where all of the circuit components are formed on a semiconductor substrate and the case where the main components of the circuit are integrated. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate. By integrating these circuits as one LSI, the circuit area can be reduced.

  Another embodiment of the present invention is an electronic device. The electronic device includes an FM transmitter according to any one of the above-described aspects, a host processor connected to the FM transmitter via a predetermined bus, obtaining a predetermined value instructed by a user, and transmitting the predetermined value to the FM transmitter. . The FM transmitter sets a predetermined value designated by the user in the data item.

  Still another embodiment of the present invention relates to an automatic channel selection method using RDS (Radio Data System) / RBDS (Radio Broadcast Data System). This method includes a step of setting a predetermined value in an RDS / RBDS data item that can be set as a channel selection reference in the FM transmitter, and an RDS / RBDS format in which the predetermined value is set as the data item. A step of generating data and a step of frequency-modulating and outputting data in the RDS / RBDS format are executed. In the FM receiver, a step of receiving radio waves, decoding data in the RDS / RBDS format, extracting a channel having a predetermined value as a data item that can be used as a channel selection reference, and performing tuning is executed.

  According to this aspect, automatic tuning can be performed by matching data items set in the transmitter and the receiver with predetermined values.

  It should be noted that any combination of the above-described constituent elements, and those obtained by replacing constituent elements and expressions of the present invention with each other among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  According to the present invention, automatic channel selection is possible.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

In this specification, “the state in which the member A and the member B are connected” means that the member A and the member B are physically directly connected, or the member A and the member B are in an electrically connected state. Including the case of being indirectly connected through other members that do not affect the above.
Similarly, “the state in which the member C is provided between the member A and the member B” refers to the case where the member A and the member C or the member B and the member C are directly connected, as well as an electrical connection. The case where it is indirectly connected through another member that does not affect the state is also included.

  FIG. 1 is a block diagram showing an overall configuration of an electronic device 200 equipped with an FM transmitter 100 according to an embodiment of the present invention. The electronic device 200 is, for example, a mobile phone terminal, a radio receiver, or a silicon audio player, and has an audio playback function. The reproduced audio signal can be output from an electroacoustic conversion element itself such as a speaker or an earphone included in the electronic device 200 itself. In addition to this, the electronic device 200 can modulate the frequency of an audio signal and transmit it as a radio wave to the outside in order to enable audio reproduction with higher sound quality. The user can receive the transmitted signal by an external audio player and reproduce it with higher sound quality.

  The FM transmitter 100 according to the present embodiment can transmit character data in addition to audio data. For this purpose, the FM transmitter 100 and the host processor 120 generate a signal compliant with RDS / RBDS. Note that when RDS / RBDS is written, it means either one or both.

  The electronic device 200 includes a sound source 110, a host processor 120, an FM transmitter 100, and an antenna 112. The sound source 110 and the host processor 120 may be the same IC.

  The sound source 110 outputs an audio signal S1. For example, the audio signal S1 may be a signal obtained as a result of receiving and demodulating a broadcast wave, or may be a signal obtained by reproducing data stored in a memory, and its generation method is not limited. The sound source 110 and the FM transmitter 100 are connected by a bus 114 having a predetermined format. For example, the bus 114 is an I2S bus. In this case, the audio signal S1 is transmitted as serial data between the sound source 110 and the FM transmitter 100.

  The FM transmitter 100 receives the audio signal S1 from the sound source 110. The FM transmitter 100 includes an interface unit 20, a stereo modulator 22, a frequency modulator 24, a power amplifier 26, a memory 10, and a data generation unit 12, and is integrated as a function IC (Integrated Circuit) on a single semiconductor substrate. Has been. FIG. 1 shows only main circuit blocks extracted, and other blocks are omitted as appropriate.

  The interface unit 20 receives the audio signal S <b> 1 from the sound source 110 via the input terminal 102. The interface unit 20 receives the audio signal S 1 and outputs it to the stereo modulator 22. The stereo modulator 22 performs stereo modulation on the audio signal S1 to generate a stereo composite signal S2.

  Details of RDS / RBDS are described in detail in Non-Patent Document 1 and the like, so please refer to them. The host processor 120 outputs data D1 to be transmitted as RDS / RBDS. The data D1 itself to be transmitted is not text data in the RDS / RBDS format but only text data. The host processor 120 and the FM transmitter 100 are connected by a bus 116 having a predetermined format. For example, the bus 116 is an I2C bus. The interface unit 20 receives the data D1 through the bus 116 and the input terminal 104. Data D1 is additional data to be transmitted from the antenna 112 together with the audio signal S1. Further, it is desirable that data transmission from the host processor 120 to the FM transmitter 100 is performed only at a timing at which RDS / RBDS data to be transmitted from the antenna 112 is changed. In this case, the contents of the memory 10 are updated only when the data is changed.

  The memory 10 is composed of a register or the like and stores data D1 received by the interface unit 20. In the RDS / RBDS format, the same data is repeatedly transmitted. The host processor 120 collectively outputs data as a repetition unit to the FM transmitter 100.

For example, the data D1 is
1) Broadcaster name 2) Text information (Radio Text)
3) Music / Voice 4) Program type 5) PI (Program identification)
Including at least one code or a combination thereof. 1) includes “broadcasting station name” as text data. “Music / voice” in 3) indicates whether the data being broadcast is music or voice. The “program type” in 4) indicates the genre of data being broadcast. For example, “0 no definition”, “1 news”, “3 sports”, “14 jazz”, “15 classic”, and the like are set. The PI of 5) is a code that enables the receiver to identify the country.

  The data generation unit 12 appropriately rearranges the data D1 stored in the memory 10, and generates group data G1 that conforms to the RDS / RBDS format. The group data G1 is generated every predetermined timing, for example, every 87.6 ms. Accordingly, the group data G1 is repeatedly output to the adder 28 every 87.6 ms. The adder 28 adds the stereo composite signal S2 from the stereo modulator 22 and the group data G1. The frequency modulator 24 frequency-modulates the carrier wave using the group data G1 as a modulation signal. The modulated signal output from the frequency modulator 24 is amplified by the power amplifier 26 and output to the antenna 112 via the output terminal 106 and a matching circuit (not shown). The antenna 112 transmits frequency-modulated data.

FIG. 2 shows the format of the RDS group data G1. The group data 40 (G1) is composed of 104 bits. The group data G1 is generated every 87.6 ms and output from the data generation unit 12. Group data G1 includes four blocks 41-44. Each block is composed of 26 bits and includes a 16-bit information word 50 and a 10-bit check word 52. The information word of the first block 41 includes a PI code.
The information word includes a 4-bit (A3 to A0) group type code 54, a 1-bit (B0) version code 60, a 1-bit (TP) traffic program identification code 62, and a 5-bit (PT4 to PT0) program type code. 64.
A group type code 54 for designating the use of the group is assigned to the head of the second block 42 of each group. The program type code 64 and the traffic program identification code 62 are assigned to predetermined positions in the second block 42 of each group.

  The check word includes 10 bits, and is a bit for detecting and correcting an error caused by transmission on the transmission side and the reception side. The offset is data indicating the number of the block that includes the offset. The check word is generated according to a predetermined rule defined by the standard.

  The remaining data to be transmitted is assigned to the remaining bits. Two characters of data can be transmitted per block. The data generation unit 12 in FIG. 1 refers to the memory 10 every predetermined timing, that is, every 87.6 ms, and generates group data G1 conforming to the format in FIG.

The FM transmitter 100 configured as described above has the following effects.
First, it is not necessary for the host processor 120 to generate data in the RDS / RBDS format. Therefore, a conventional host processor can be used, and data to be transmitted may be transmitted to the FM transmitter 100 using a conventional bus (for example, I2C).

  Further, as described above, data transmitted by RDS / RBDS includes data that is repeatedly transmitted for each block or group. Therefore, if RDS / RBDS data is generated in the host processor 120, all bits of the group data G1 that are repeatedly transmitted are generated, and 104 bits of data are generated every 87.6 ms (f = 1.19 kHz). It is necessary to transmit from the host processor 120 to the FM transmitter 100 every time via the 116. Whatever the format of the bus 116, power transmission occurs for data transmission therethrough. Therefore, in this method, the same data is retransmitted each time for the bits to be transmitted in duplicate, so that useless power is generated. On the other hand, according to the FM transmitter 100 according to the present embodiment, data to be transmitted is transmitted from the host processor 120 to the FM transmitter 100 in a lump and is held in the memory 10. As a result, data transmission after the next time is not required, and redundant data transfer is reduced, so that power consumption is reduced.

Further, from the host processor 120,
1) Broadcaster name 2) Text information 3) Music / voice 4) Program type 5) PI (program identification)
The data that can be generated in the FM transmitter 100 such as a check word is not transmitted from the host processor 120 to the FM transmitter 100, so that the FM transmitter 100 and the host processor 120 can further transmit data. The amount of data transmitted can be reduced.

  The host processor 120 performs overall processing of the entire electronic device 200. Therefore, when RDS / RBDS data is generated every 87.6 ms and transmitted to the FM transmitter 100, the processing capability of the host processor 120 is occupied, which is not desirable. In this embodiment, the load on the host processor 120 can be reduced.

  Further, data transmission through the bus 116 may generate noise, adversely affect stereo modulation and frequency modulation, and deteriorate the characteristics of the FM transmitter 100. Since the number of data transmissions and the amount of data can be reduced, the characteristics of the FM transmitter can also be improved.

If the host processor 120 can generate data in the RDS / RBDS format, the FM transmitter 100 may be implemented with a general-purpose mode described below.
The host processor 120 generates RDS / RBDS format data therein, and outputs the data to the FM transmitter 100 via the bus 116. The data in the RDS / RBDS format at this time does not include a check word. The data generation unit 12 adds a check word to the RDS / RBDS format data received from the host processor 120 and outputs the data to the adder 28.
If the general-purpose mode is implemented, various data other than the data described above can be transmitted. Further, although data transmission through the bus 116 occurs every 87.6 ms of transmission timing, check data is not transmitted, so that power consumption can be reduced.

  Next, an automatic channel selection technique for tuning the FM transmitter 100 and the receiver using RDS / RBDS data will be described. The automatic channel selection technique according to the present embodiment may use the above-described FM transmitter 100 or may use another technique. Below, it demonstrates on the assumption of the FM transmitter 100 shown in FIG.

  A technical feature of RDS / RBDS is that the receiver can perform a tuned search using predetermined data items (hereinafter also simply referred to as codes). That is, in a receiver such as a radio tuner, when a user sets a predetermined value “news” in a certain code “for example, program type”, the broadcast wave is scanned over the entire band, and RDS / RBDS data of the channel being broadcasted Get and decode. As a result of decoding, a channel including a predetermined value “news” in the program type is automatically selected. When there are a plurality of channels, the user can select one.

The automatic channel selection technique according to the present embodiment will be described in detail.
The data generation unit 12 in FIG. 1 sets a predetermined value in a data item (tuning search keyword) that can be used as a channel selection reference on the receiving side, and generates data in RDS / RBDS format. The frequency modulator 24 frequency-modulates the RDS / RBDS format group data G1 generated by the data generator 12 together with the stereo composite signal S2 from the stereo modulator 22 and outputs the result.

For example, the data item is preferably “program type”. The value of the program type can be set in 32 ways from “0 no program type” to “31 alarm”. It is desirable that the user of the electronic device 200 can specify which value is set. In this case, the host processor 120 acquires the value of the program type designated by the user via a user interface (not shown). The host processor 120 outputs a value designated by the user as the program type as data D1. This program type code is written in the memory 10, and the data generation unit 12 can generate data based on a user-specified value.
As another embodiment, the program type may be preset in the FM transmitter 100.

  The program type may be set regardless of the type of data transmitted from the FM transmitter 100. That is, when the transmitted audio signal is “lock”, there is no problem that the value of the program type set by the user is “news”.

  Further, a “music / voice” code may be used instead of the program type. In this case, either “music” or “voice” is set as the value. In this case, the music / voice code may be set regardless of the type of data transmitted from the FM transmitter 100.

  In a normal usage mode, the user of the electronic device 200 is the same as the user of the radio tuner (receiver). Therefore, since the user knows the value set as the program type in the FM transmitter 100, the value can be set as the program type of the receiver.

That is, in the automatic channel selection method according to the present embodiment, the following processing is executed.
First, in the FM transmitter 100,
(1) A predetermined value is set in an RDS / RBDS data item (program type, music / voice) that can be set as a channel selection reference in the receiver. The processing main body is the host processor 120 and the data generation unit 12.
(2) Generate data in RDS / RBDS format in which a predetermined value is set as a data item. The processing subject is the data generation unit 12.
(3) The RDS / RBDS format data is frequency-modulated and output. The processing subject is the frequency modulator 24.
In the receiver,
(A) A radio wave is received, data in RDS / RBDS format is decoded, and a channel whose data item has a predetermined value is extracted and tuned.

  According to the automatic channel selection technique according to the present embodiment, a channel having a predetermined value in which a program type is set is automatically selected in the receiver. From the FM transmitter 100, RDS / RBDS data whose program type has a predetermined value is respected. Therefore, the user can perform tuning without inputting the transmission frequency of the FM transmitter 100 to the receiver.

  When a plurality of channels are extracted, the user may select a channel of FM transmitter 100 from among them. At the same time, it is rare for programs by broadcast waves to have the same value as the program type, so the user can select at most a few channels and set the frequency himself. You can tune in more easily than in the case.

  In other transmitters than FM transmitter 100 according to the present embodiment, the program type will generally be set to “0 no program type”. Alternatively, the value of the program type may be data corresponding to the content of the signal transmitted from the FM transmitter 100. On the other hand, the present embodiment is characterized in that the value of the program type is positively set to a certain value and used for automatic channel selection.

  Although the present invention has been described based on the embodiments, the embodiments merely illustrate the principle and application of the present invention, and the embodiments are intended to include the idea of the present invention defined in the claims. Many modifications and changes in arrangement are possible within the range not leaving.

  Although the FM transmitter 100 according to the embodiment has been described on the assumption of the FM transmitter 100 of FIG. 1, the present invention related to automatic channel selection is not limited to this. That is, the host processor 120 itself may generate RDS / RBDS data and transmit it to the FM transmitter 100 every 87.6 ms. Even in this case, the antenna 112 transmits a modulated signal whose data item to be tuned search has a predetermined value, so that automatic channel selection is possible.

It is a block diagram which shows the whole structure of the electronic device carrying the FM transmitter which concerns on embodiment of this invention. It is a figure which shows the format of the group data of RDS.

Explanation of symbols

  10 memory, 12 data generation unit, 20 interface unit, 22 stereo modulator, 24 frequency modulator, 26 power amplifier, 28 adder, 100 FM transmitter, 102 input terminal, 104 input terminal, 106 output terminal, 114 bus, 116 buses, 110 sound sources, 112 antennas, 120 host processors, 200 electronic devices.

Claims (9)

An FM transmitter capable of transmitting a signal compliant with RDS (Radio Data System) or RBDS (Radio Broadcast Data System) format,
A data generation unit that sets a predetermined value in a data item that can be used as a channel selection reference on the receiving side, and generates data in an RDS / RBDS format;
A frequency modulator that frequency-modulates and outputs the data in the RDS / RBDS format generated by the data generation unit;
An FM transmitter comprising:   The FM transmitter according to claim 1, wherein the data item is a program type.   3. The FM transmitter according to claim 2, wherein the program type is set regardless of the type of data transmitted from the FM transmitter.   The FM transmitter according to claim 1, wherein the data item is a music / voice code.   5. The FM transmitter according to claim 4, wherein the music / voice code is set regardless of a type of data transmitted from the FM transmitter.   The FM transmitter according to claim 1, wherein the data generation unit sets the predetermined value in accordance with a user designation.   7. The FM transmitter according to claim 1, wherein the FM transmitter is integrated on a single semiconductor substrate. An FM transmitter according to any of claims 1 to 6;
A host processor connected to the FM transmitter via a predetermined bus, acquiring the predetermined value instructed by a user, and transmitting the predetermined value to the FM transmitter;
With
The said FM transmitter sets the said predetermined value instruct | indicated by the said user to the said data item, The electronic device characterized by the above-mentioned. In FM transmitter,
Setting a predetermined value in an RDS / RBDS data item that can be set as a channel selection reference in the receiver;
Generating RDS / RBDS format data in which the predetermined value is set as the data item;
Frequency-modulating and outputting the data in the RDS / RBDS format;
Run
In FM receiver,
Receiving radio waves, decoding data in RDS / RBDS format, and extracting and tuning a channel in which a data item that can be used as a reference for channel selection has the predetermined value is executed. Automatic channel selection method.

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