JP2562820B2 - Radio data receiver - Google Patents

Description

TECHNICAL FIELD The present invention relates to a receiver of a radio data system (hereinafter referred to as an RDS receiver).

BACKGROUND ART Broadcasting-related information such as information related to the program content is transmitted as data at the time of broadcasting from a broadcasting station by multiplex modulation, and the desired program content can be selected on the receiving side based on the demodulated data. In this way, a radio data system (RD that enables the service to be provided to radio listeners
S) there.

In the Radio Data System, a 57KH _z is a third harmonic of a stereo pilot signal 19KH _Z in the frequency band of the FM-modulated wave as a subcarrier, filtered the subcarrier and is biphase (Biphase) encoding In addition, a radio data signal is amplitude-modulated by a data signal indicating information related to broadcasting such as program content, and the amplitude-modulated subcarrier is frequency-modulated as a main carrier frequency for broadcasting.

As is clear from FIG. 3 showing the baseband coding structure of the radio data signal, 104 bits correspond to 1 bit.
It is repeatedly multiplexed and transmitted as a group. One group consists of 4 blocks each having 26 bits, and each block consists of a 16-bit information word and a 10-bit check word. In FIG. 4, a block 1 is a program recognition (PI) code representing a network, a block 2 is a traffic program recognition (TP) code, and a block 3 is a station frequency of a network station broadcasting the same program ( AF) data, and in block 4, program service information (PS) data such as a broadcasting station name and a network name are arranged. Also, each group is classified into 16 types of types 0 to 15 in 4 bits according to the content, and two versions A and B are defined for each type (0 to 15), These recognition codes are located in block 2. The station frequency (hereinafter abbreviated as AF) data of the network station is transmitted only in the type OA group, and program service name information (hereinafter abbreviated as PS).
The data is to be transmitted in type OA and OB groups.

However, since such radio data is transmitted by a digital code, it is easily affected by noise when the reception state of the RDS broadcast wave is not good. Therefore, when multiple RDS broadcast waves of the same network can be received, the reception state is It is desirable to be able to easily select the best broadcasting station.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a radio data receiver capable of easily selecting a radio data broadcasting station having the best reception state for each network of the same program.

The radio data receiver of the present invention has a control function based on radio data superimposed on broadcast waves, and sweeps the reception frequency band in accordance with a command to receive frequency data of broadcast waves that can be received by a plurality of preset channels. It is a radio data receiver that can be stored in the memory corresponding to each and preset frequency can be selected using the frequency data stored in the memory.Each time the broadcast wave is received during the sweep, the frequency data of the received broadcast wave is received. The same as the received data reading means for reading the received signal level and the program recognition information as the received data, and the judgment means for judging whether or not a plurality of received data having the same program recognition information has been read by the received data reading means. When a plurality of received data having the program recognition information is read, the received signal levels of the plurality of received data are compared with each other. In comparison with the above, the reception data indicating the maximum reception signal level is determined, and only the frequency data included in the determined reception data is written in the memory as the frequency data of one preset channel. .

Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In the RDS receiver to which the control method of the present invention shown in FIG. 1 is applied, the FM multiplex broadcast wave received by the antenna 1 is converted to an intermediate frequency (IF) by selecting a desired station in the front end 2. FM detector 4 via IF amplifier 3
Is supplied to. The front end 2 converts the local oscillation signal to the mixer 2b into a P signal using a PLL circuit 2a including a programmable frequency divider.
It is obtained by the LL synthesizer method, and the tuning operation is controlled by the controller 14 which delays the frequency division of the programmable frequency divider.
The detection output of the FM detector 4 is supplied to the MPX (multiplex) demodulation circuit 5, and in the case of stereo broadcasting, L (left), R
It is separated into (right) channel audio signals.

Further, since the detection output of the FM detector 4 is passed through the filter 6, demodulated by a biphase-coded data signal subcarrier amplitude-modulated 57KH _z, i.e. in the PLL circuit 7 is extracted radio data signal It This demodulated output is the digital (D) PLL circuit 8 and the decoder 9.
Is supplied to. The D-PLL circuit 8 generates a data demodulation clock based on the demodulation output of the PLL circuit 7. The generated clock is supplied to the gate circuit 10. The lock detection circuit 11 detects that the D-PLL circuit 8 is locked, generates a lock detection signal, supplies the lock detection signal to the gate circuit 10, and controls the circuit 10 to be in an open state. In the decoder 9, the bi-phase coded data signal which is the demodulated output of the PLL circuit 7 is decoded in synchronization with the clock generated in the D-PLL circuit 8.

As shown in FIG. 3, the output data of the decoder 9 is in units of 104 bits consisting of four blocks each having a 26-bit configuration, and is sequentially supplied to the group and block synchronization & error detection circuit 12. In the group / block synchronization & error detection circuit 12, the group and block are synchronized based on the 10-bit offset word assigned to the 10-bit checkword of each block, and the 16-bit information is based on the checkword. Word error detection is performed. Then, the error-detected data is supplied to the controller 14 after the error is corrected by the error correction circuit 13 at the next stage.

The controller 14 is composed of a microcomputer, and code information of each block in the radio data that is sequentially input in units of groups, that is, radio data information related to the program content of the broadcasting station currently being received (the PI code and AF data described above). , PS data, etc.) and capture it in the memory 15. Further, the sweep mode is set based on the sweep command from the sweep mode button 23 of the operation unit 16, and the frequency division ratio of the programmable frequency divider (not shown) of the PLL circuit 2a forming a part of the front end 2 is determined. Control frequency data values. This reception frequency data value is, for example, the count value of the counter.

On the other hand, the station detection circuit 20 outputs an IF signal of a predetermined level or higher as a station detection signal in the IF amplifier 3, and the station detection signal is supplied to the controller 14.

The memory 15 is composed of a nonvolatile RAM in which data such as reception frequency data, PI code, AF data, etc. is written, and a ROM in which programs and data are written in advance.
In addition to the sweep mode button 23 described above, the operation unit 16 also has preset channel buttons 25 (“1” to “6”, etc.) for selecting a channel by selectively reading a plurality of preset reception frequency data. ) Operation buttons are provided.

Next, a controller 14 showing the procedure of the control method of the present invention.
The operation of the processor will be described with reference to the flowchart shown in FIG.

When the processor enters the sweep mode by operating the sweep mode button 23 of the operation unit 16, it changes the reception frequency data value supplied from the controller 14 to the PLL circuit 2a of the front end 2 to the minimum value (step 51), and the station detection signal is transmitted. It is determined whether it has occurred (step 52). If the broadcast wave cannot be received at the reception frequency, the station detection signal is not generated. Therefore, it is determined whether or not a predetermined time has elapsed after changing the reception frequency data value (step 53). For example, the received frequency data value is increased by a predetermined value (step 54), it is determined whether the received frequency data value exceeds the maximum value (step 55), and if the received frequency data value is less than the maximum value, the process proceeds to step 52. Transition. Thus, increases to a maximum frequency from the frequency divider of the frequency division of the reception band minimum frequency is the receiving frequency varies at a predetermined step of the PLL circuit 2a for example, every predetermined time 100KH _Z units depending on the received frequency data value . The predetermined time is slightly longer than the time from when the received frequency data value is increased to when the broadcast wave can be received until the station detection signal by the broadcast wave is obtained.
On the other hand, when a new broadcast wave is received, the IF signal level rises above a predetermined level and the station detection circuit 20 generates a station detection signal. When this station detection signal is generated, the data supplied from the error correction circuit 13 is input (step 56), and it is determined whether or not the input data is obtained (step 57).
If no input data is obtained, the received broadcast wave is not the RDS broadcast wave, and therefore the process proceeds to step 54 for further sweeping.

If input data is obtained, PI is calculated from the input data.
Read the code and set it as PI _IN (step 58), read the reception frequency data at that time and set it as f _IN (step 59), read the station detection signal level and set it to S
_Set to _IN (step 60). Then, it is determined whether or not the variable _n is equal to 0 (step 61). If n = 0, it means that the sweep operation has just started, so 1 is added to the variable n (step
62), the read PI code, the reception frequency data and the station detection signal level as one reception data D _n , that is, PI
_{IN is set} to PI _n , f _{IN is set} to f _n , and S _{IN is set} to S _n , and written in the memory 15 (step 63), and the process proceeds to step 54 for further sweeping. The variable n is initialized to 0 when the sweep mode is entered. In the memory 15, the received data D ₁ ...... D _n
The writing position is written in advance.

If n ≠ 0, set the variable x equal to 1 (step 6
4), PI _X is read from the memory 15, and it is determined whether the read PI _IN is equal to the PI _X (step 65). PI _IN
= If PI _X, because it is the same network, the memory 15
Read S _X from the read S _IN from the read S _IN
It is determined whether _X is large (step 66), S _X ≧ T _IN
If so, the received signal level is smaller than the RDS broadcast wave of the same network that has already been received, and therefore the process proceeds to step 54 for further sweeping. However, if S _X <S _IN, then
The received signal level of the RDS broadcast wave received this time is higher than that of the RDS broadcast wave of the same network that has already been received.
_{IN is set} to PI _X , f _{IN is set} to f _X , S _{IN is set} to S _X , and the received data is updated in the memory 15 (step 67), and the process proceeds to step 54 for further sweeping.

If P _IN ≠ PI _X , it is judged whether the variable n is equal to the variable x because the networks are different (step 68). The variable n represents the number of networks already stored in the sweep process, so if the number of RDS broadcast wave networks is 1, n =
It is 1. If n> x, 1 is added to the variable x in order to check whether it matches another network that has already been received (stored) (step 69), and the process proceeds to step 65. n =
If it is x, it is the broadcast wave of the network received for the first time in the sweep operation, and therefore the process proceeds to step 62 for registration.

On the other hand, when the reception frequency data value exceeds the maximum value, the sweep operation within the reception band ends. At this time, memory 15
The received data for n different networks having the maximum received signal level are stored therein. Therefore, the received frequency data obtained is stored in the memory 15
The variable x is set equal to 1 to write it to the preset storage position (step 70), the reception frequency data f _X is read and written to the preset storage position corresponding to the preset channel x (step 71). Then, it is determined whether or not the variable n is equal to the variable x (step 72), and if n> x, 1 is added to the variable x (step 71), and the process proceeds to step 71. If n = x, it is assumed that all the reception frequency data have been preset, and the sweep mode ends.

When the variable n, that is, the number of RDS broadcast networks obtained by the sweep operation is larger than the preset channel number (6 channels in this case), the excess is ignored.

As described above, in the radio data receiver of the present invention, the reception frequency data of only the broadcast wave having the maximum reception signal level of the radio data broadcast wave received by the sweep operation is preset in the memory for each network. By preset tuning, it becomes possible to easily select the radio data broadcasting station having the best reception condition.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an RDS receiver to which the present invention is applied, FIG. 2 is a flow chart showing an operation of a processor in a controller in the receiver of FIG. 1, FIG. 3 is a diagram showing a baseband coding structure of a radio data signal, and FIG.
The figure shows the format of the type OA group. Description of symbols of main parts 1 ... Antenna, 2 ... Front end, 4 ... FM detector, 5 ... Multiplex demodulation circuit, 8 ... Digital
PLL circuit, 9 ... Decoder, 14 ... Controller, 20 ...
... Station detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-89123 (JP, A) Nikkei Electronics, August 24, 1987, pages 202-217.

Claims (1)

(57) [Claims] 1. A control function of radio data superimposed on a broadcast wave, wherein frequency data of a receivable broadcast wave is made to correspond to each of a plurality of preset channels by sweeping within a reception frequency band in accordance with a command. Stored in memory,
A radio data receiver capable of preset tuning using frequency data stored in the memory, wherein frequency data of a received broadcast wave, received signal level and program recognition information are received every time a broadcast wave is received during the sweep. Reception data reading means for reading as reception data; discrimination means for discriminating whether or not a plurality of reception data having the same program recognition information are read by the reception data reading means; and reception data having the same program recognition information. When a plurality of received data are read, the received signal levels of the plurality of received data are compared with each other, the received data indicating the maximum received signal level is determined, and the frequency data included in the determined received data is set as one preset. A means for writing to the memory as frequency data of a channel, Over data receiver.