JPH0511810B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Technical Field] The present invention relates to a radio receiver that receives broadcast waves on which data signals are superimposed.

[Background of the invention] Conventionally, in West Germany and other countries, a system (Autofahrer Rundfunk
Information (abbreviated as ARI) has been devised.

This ARI is the pilot tone of FM broadcasting.
A subcarrier was added to 57KHz, which is the third harmonic of 19KHz, as an identification signal, and this was frequency-converted to the main carrier for broadcasting. This identification signal
It was called an SK signal, and by demodulating this SK signal, the demodulating side made it easier to receive broadcasting stations supplying traffic information.

However, the ARI system only provides identification for traffic information stations and does not provide any further services.

Therefore, we use FSK (Frequency Shift Keying) to transmit biphase coded data signals on the same 57KHz subcarrier with a phase that is 90° different from the ARI phase.
A system that modulates and transmits (Radio Data
System (abbreviated as RDS system) was proposed.

As seen in the baseband coding shown in FIG. 1, the data supplied in the RDS system consists of four blocks each consisting of 26 bits forming one group.

Each block contains 16-bit information words and 10
It consists of a bit check word and an offset word, and the receiving side can receive various services by demodulating the information word.

Basic information will be explained based on the data format shown in FIG.

The first block is given 16 bits of program identification information (PI code). This PI code consists of a total of 16 bits: a country code (4 bits), a broadcast range code (4 bits), and a program reference number code (8 bits), and it is used to determine which country the broadcast is from and whether the same broadcast is available in other countries. Information such as whether the program is being played, whether it is a local program or a major program, etc., is sent as data based on predetermined rules.

The second block is given a group type identification code consisting of a group type code (4 bits) and a version code (1 bit), a total of 5 bits. This group type identification code is used to identify what data is being sent after that, and theoretically it is possible to identify 2 ⁵ = 32 group types, but currently Two versions, versions A and B, are defined for the four groups 0 to 3, and an undefined group is added to these to make a total of nine groups identifiable. Although the types of data that are subsequently sent differ depending on the group, their explanation will be omitted here.

Following the group type identification code: Transportation program code (TP code, 1 bit) Program type code (PTY code, 5
(bit) Traffic announcement code (TA code, 1 bit) Music/speech switch code (M/S code, 1 bit) Decoder control bit (DI bit,
Address bits (1 bit) and address bits (2 bits) are given.

In the above data, the TP code and TA code indicate whether the broadcasting station is a traffic information station or whether it is currently broadcasting by a combination of the respective codes.

There are 32 types of PTY codes from 0 to 31 (music programs, news programs, sports programs, etc.)
It is given based on predetermined rules, and a list is shown in Table 1.

No. PTY code Program type 1 00000 No program 2 00001 News 3 00010 Current events 4 00011 Manga 5 00100 Sports 6 00101 Education 7 00110 Children's programs 8 00111 Youth programs 9 01000 Religious programs 10 01001 Drama 11 01010 Rockmiyujitsuk 12 01011 Light music 13 01100 Serious music 14 01101 Jazz 15 01110 Folk music 16 01111 Variety 17-30 Undefined 31 11111 Emergency broadcast If the M/S code is “0”, it is speech, “1”
If so, it indicates that music is being broadcast.

The DI bit provides decoding information to demodulate the incoming broadcast waves.One bit is given, but by repeating this 4 times and receiving it, 4 bits of information (16 types of decoding information) can be obtained. ).

The function of the address bit differs depending on the group type described above, but in this embodiment, it indicates the address of the PS code, which will be described later, and will be explained in detail in the explanation of the PS code.

The third block contains other station frequency information (AF code)
We are given two 8-bits, and for convenience we divide them into the first
This will be referred to as the AF area and the second AF area.

This AF code transmits frequency information of other stations that are broadcasting the same program as the station that is currently broadcasting. This frequency information corresponds to 8-bit data every 100KHz.

Number AF code Carrier frequency 0 00000000 87.5MHz 1 00000001 87.6MHz ・ ・ ・ ・ ・ ・ 204 11001100 107.9MHz 205 11001101 Temporary code The 8-bit code corresponding to a number above this has a different meaning, for example: It sends information such as how many AF stations there are.

224 11100000 There is no AF 225 11100001 There is one AF station ・ ・ ・ ・ ・ ・ 249 11111001 There are 25 AF stations AF control codes with numbers 224 to 249 like this are always the first AF of the two AF codes For example, if four AF stations are being sent, an 8-bit code indicating the number 228 is sent to the first AF area, and then an 8-bit code indicating the carrier frequency is sent to the second AF area. It will be done.

When data is next received, 8-bit codes representing the second and third frequency information are sent to the first and second AF areas, respectively, and finally an 8-bit code representing the fourth frequency information is sent to the first AF area. AF
A temporary code (number 205) is given to the second AF area, and the transmission of the AF code is completed.

Therefore, if the AF control code is demodulated and then demodulated repeatedly, a list of frequency information of other stations broadcasting the same program as the currently broadcasting station can be obtained.

The fourth block is given a program service code (PS code) in which the name of the broadcasting station is sent in ASCII code. Since the ASCII code requires 8 bits of binary code for each character, only two characters can be transmitted in the fourth block. In RDS, the broadcasting station name is 8
Since it is given in characters, ASCII data for 8 characters is obtained only after receiving data four times.

At this time, the second step mentioned above is to determine which character out of eight characters corresponds to the currently sent PS code.
This is the address bit of the block and indicates the following correspondence.

Address bit character arrangement 0 0 1st and 2nd characters 0 1 3rd and 4th characters 1 0 5th and 6th characters 1 1 7th and 8th characters In this way, the information of the PS code currently being sent by the address bits is the station name. This designates the number of characters corresponding to the 8-character broadcasting station name, and by repeating the demodulation four times on the receiving/demodulating side, it becomes possible to demodulate the eight-character broadcasting station name.

[Prior art] Using the above-mentioned RDS system, if the electric field strength of the station you want to listen to is low, the AF
Using the code, you can switch to another station that is currently broadcasting the same program and enjoy listening to the radio.

[Problem to be solved by the invention] However, when trying to search for another station using the AF code, it is natural that the reception condition of the desired broadcasting station is deteriorated, and the AF code must be sufficiently demodulated. Can not do it. Therefore, a contradiction has arisen in that the AF code is useless in situations where it should be used.

[Means for Solving the Problems] This invention aims to eliminate the drawbacks of the above-mentioned prior art, and it is possible to store frequency information when the electric field strength of a desired station is below a predetermined level. When the frequency information corresponding to the AF code and the stored frequency information match, the AF code of the receiving station is stored in the device and then demodulated by sequentially sweeping within the receiving band. This is to output audio as the receiving state.

[Embodiment] The operation of the present invention will be described below with reference to FIG.

The configurations 1 to 6 indicate a receiver with a so-called superheterodyne configuration, where 1 is an antenna, 2 is a front end, 3 is a detection circuit, 4 is an amplifier circuit, 5 is a speaker, 6 is a PLL, and PLL 6 is a system controller 9. Receives PLL data from the station and tunes to the desired receiving station. Reference numeral 7 denotes an electric field strength detection circuit that detects electric field strength from the output of the detection circuit 3, and its output is led to the system controller 9.
8 is an RDS decoder that demodulates the RDS code among the signal components branched from the output of the detection circuit 3. Here, the AF code of the third block is demodulated to convert the carrier frequency corresponding to the 8-bit AF code into the system. to the controller 9.

Reference numeral 11 denotes a memory for storing reception frequency information, which is written/written by the system controller 9.
Reading is controlled. Reference numeral 10 denotes an operation section which, in the case of a preset tuner, gives preset channel calls and sweep commands.

Next, the operation of the present invention achieved by the above configuration will be explained.

First, as is well known, a preset channel is called up using the operating section 10 and tuned to the desired reception station. When the electric field strength is below a predetermined value, the system controller 9 stores the frequency information of the desired reception station at that time in the memory 11. after that
A sweep command is given to PLL6, and PLL6 sequentially sweeps within the reception band. When a broadcasting station with an electric field strength above a certain level is received, the system controller 9 stops the sweep of the PLL 6 and displays the RDS at that time.
AF obtained by demodulating the code with RDS demodulation circuit 8
The station information and the frequency information stored in the memory 11 are sequentially compared.

As a result of the comparison, if the frequency information of the desired receiving station in the memory 11 matches the AF station of the received broadcasting station, it is obvious that the broadcasting station is broadcasting the same program as the desired receiving station. , the broadcast of that broadcast station is output from the speaker 5.

If the AF station does not match the frequency information in the memory 11, it is obvious that the station is broadcasting a different program than the desired receiving station, and the system controller 9 sends the PLL data to the PLL 6 to continue sweeping. give.

[Other Embodiments of the Invention] During the sweep operation of the PLL 6 or when comparing the AF code with the frequency information of the desired receiving station stored in the memory 11, as shown in FIG. A transistor Q with a grounded emitter is provided in the
A muting signal may be applied to the base of the speaker to mute the audio output.

Furthermore, in the embodiment shown in FIG. 3, the system controller 9 does not constantly monitor the output of the field strength detection circuit 7, but the field strength is determined by the comparator 12 that compares the output of the field strength detection circuit 7 with a reference voltage. An output signal may be given to the system controller 9 when the voltage is lower than the voltage.

[Effects of the Invention] As described above, according to the present invention, even if the reception condition of a desired broadcasting station is poor, it is possible to automatically switch to a broadcasting station that is broadcasting the same content as that broadcasting station. A practically extremely effective receiving system can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the data format of the RDS system, FIG. 2 is a block diagram showing the configuration of a receiver according to the invention, and FIG. 3 is a block diagram showing another embodiment of the invention. 2...Front end, 3...Detection circuit, 4...Amplifier, 6...PLL, 7...Field strength detection circuit, 8...
RDS decoder, 9...System controller, 1
0...Operation unit, 11...Memory.

Claims (1)

[Claims] 1 A receiver that receives a broadcasting system that superimposes frequency information of other broadcasting stations that are broadcasting the same program as the own station's broadcast content on frequency components other than the main signal component of FM broadcast waves as data, and that the receiver wishes to receive. a receiving circuit that stores frequency information of a station in a storage means when the field strength of the station is below a predetermined value, and then sequentially sweeps within the reception band; A radio characterized in that the frequency information of other stations obtained by demodulating data is compared with the frequency information stored in the storage means, and when they match, the sweep state is stopped, and when they do not match, the sweep is further continued. Data system receiver.