JPH01160221A - Method for selecting receiving frequency in rds receiver - Google Patents

Abstract

PURPOSE:To maintain an always stable receiving condition by comparing the program recognition (PI) data of respective broadcasting waves with the PI data of a former receiving station in the order of the degree of a receiving signal level, and making the same network station frequency, which the PI data coincide first, into a new receiving frequency. CONSTITUTION:By the processor of a controller 14, the fetching of each receiving signal level of the same network station frequency is successively repeated until it is completed to all network station frequencies. Station group frequency (AF) data with a highest level of respective receiving signal levels stored in a memory 15 are read, and a tuning action based on the AF data is executed. Next, PI data to express the network of such a receiving station are fetched. Whether or not the PI data coincide with the held PI data is decided. At the time of a coincidence, the same network station frequency in the middle of receiving at present is made into the new receiving frequency, and a made is shifted to an ordinary receiving mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a radio data system receiver (hereinafter referred to as RD).
The present invention relates to a reception frequency selection method in a receiver (referred to as an S receiver).

Background Art When a broadcast station broadcasts, broadcast-related information such as information related to the program content is transmitted as data through multiplex modulation, and the receiving side can select the desired program content based on the demodulated data. The Radio Data System (RD), which was able to provide its services to radio listeners,
There is S).

In this radio data system, 3 of the 19KHz stereo pilot signal is outside the frequency band of the FM modulated wave.
The next harmonic, 57 KHz, is used as a subcarrier, and this subcarrier is filtered and biphase (Blpha).
se) The radio data signal is amplitude-modulated using a data signal indicating broadcast-related information such as coded program content, and the amplitude-modulated subcarrier is frequency-modulated to the main carrier and then broadcast. There is.

As is clear from Figure 3, which shows the baseband coding structure of the radio data signal, 104 bits are divided into 1
Multiplex transmission is repeated as a group. A group consists of four blocks of 26 bits each, and each block consists of a 16 bit information word and a 10 bit check word. In Figure 4, block 1 contains program recognition (PI) data representing the network, block 2 contains traffic program recognition (TP) data and traffic announcement recognition (TA) data, and block 3 contains broadcasts of the same program. The frequency of the network station group (AF
) data, and block 4 contains program service name information (PS) data such as broadcasting station names and network names. Furthermore, each group is classified into 16 types, 0 to 15, using 4 bits according to its content, and two versions, A and H, are defined for each type (0 to 15), and these The recognition code is placed in block 2. In addition, A of the network station
F data is transmitted only in type OA groups.

By the way, in the case of a vehicle-mounted receiver, the reception condition of the broadcast wave being received may deteriorate as the vehicle travels.

However, in the case of RDS broadcasting, as mentioned above, when one RDS broadcast wave is received, it is possible to obtain AP data of a group of network stations broadcasting the same program, so this AF data can be used to improve the received signal level. It is possible to select another same network station with a higher (received electric field strength).

SUMMARY OF THE INVENTION Therefore, the present invention provides an RDS receiver that can maintain stable reception at all times by selecting the frequency of the same network station with the best reception when selecting stations within the same network. The purpose of this invention is to provide a receiving frequency selection method.

The reception frequency selection method according to the present invention is based on an RDS that can receive RDS broadcast waves including AF data and PI data of the same network station group and has the function of following the same program.
In the receiver, the PI data obtained by demodulating the broadcast wave of the current receiving frequency is held, and the receiving frequency is sequentially switched to the frequency of other same network stations given by the AF data, and each received signal level is captured. PI obtained from each broadcast wave by switching the reception frequency again to another same network station frequency in order of the highest received signal level
It is characterized in that the data is compared with the retained PI data, and the same network station frequency with which the PI data first matches is set as the new receiving frequency.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 1 showing an example of the configuration of an RDS receiver to which the reception frequency selection method according to the present invention is applied, the front end 2 selects a desired station of the FM multiplex broadcast wave received by the antenna 1, and the intermediate frequency ( IF), then I
The signal is supplied to a 1M detector 4 via an F amplifier 3. The front end 2 includes, for example, a programmable frequency divider P
Controller 1 adopts one type of PLL synthesizer using a LL circuit, and the division ratio of the programmable frequency divider is described later.
4, the channel selection operation is performed. The detection output of the 1M detector 4 is supplied to an MPX (multiplex) demodulation circuit 5, where it is separated into L (left) and R (right) channel audio signals in the case of stereo broadcasting.

Furthermore, when the detection output of the 1M detector 4 passes through the filter 6, a 57 KHz subcarrier amplitude-modulated by the pie-phase coded data signal, that is, a radio data signal is extracted and demodulated by the PLL circuit 7. . This demodulated output is supplied to a digital (D) PLL circuit 8 and a decoder 9. In the D-PLL circuit 8, the PLL
A clock for data demodulation is generated based on the demodulated output of the 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 this to the gate circuit 10, and controls the circuit 10 to be in an open (oven) state. The lock detection signal is also supplied to the AND circuit 17 as a synchronization detection signal indicating that synchronized demodulated data is obtained. In decoder 9, P
A biphase coded data signal, which is the demodulated output of the LL circuit 7, is decoded in synchronization with the clock generated by the D-PLL circuit 8.

As shown in FIG. 3, the output data of the decoder 9 is in groups of 104 bits each consisting of 4 blocks each having a 26-bit configuration, and the data is sequentially grouped.

The signal is supplied to the block synchronization & error detection circuit 12.

The group and block synchronization & error detection circuit 12 performs group and block synchronization based on the 10-bit offset word assigned to the 10-bit check word of each block, and also performs 16-bit information based on the check word. Word error detection is performed. Then, the error-detected data is error-corrected in the next-stage error correction circuit 13, and then the controller 1
4.

The controller 14 is constituted by a microcomputer, and includes code information of each block in radio data that is sequentially input in groups, that is, radio data information related to the program content of the broadcasting station currently being received (the above-mentioned PI
data, AF data, PS data, etc.) and stored in the memory 15, and based on the channel selection command from the operation unit 16, a programmable frequency divider (not shown) of the PLL circuit that constitutes a part of the front end 2. The channel selection operation is performed by controlling the reception frequency data value that determines the frequency division ratio of (1).

In addition, a level detection circuit 17 detects the received signal level (field strength) based on the IF signal level in the IF amplifier 3, and a so-called S curve characteristic in the FM detector 4 when the IF signal level in the 1F amplifier 3 is equal to or higher than a predetermined level. A station detection circuit 18 is provided which detects a receiving station and outputs a station detection signal when the detection output of the level detection circuit 17 is within a predetermined level range. A station detection signal output from the controller 14 is supplied to the controller 14.

Next, a second explanation will be given of the procedure of the receiving frequency selection method according to the present invention executed by the processor of the controller 14.
The explanation will be given according to the flowchart shown in the figure. Note that the memory 15 has already been loaded with AF data obtained by demodulating received broadcast waves, and has already created an AF data list f++f2...fn of the same network station as the broadcasting station currently being received. shall be taken as a thing.

The processor first determines whether the operating mode is the normal reception mode (step S1), and if it is not the normal reception mode, determines whether there is a switching request based on the AF data list (step S2). This switching request is made, for example, when the received signal level of the current received frequency falls below a set level. If there is a switching request, "capture the PI data obtained from the broadcast wave currently being received and its reception frequency and store it in an accumulator etc." step S3), and then read the 1 AF data in the list according to the AF data list. The AF data is read from the memory 15 (Step S4), and a tuning operation is performed by outputting this AF data to a PLL circuit (not shown) in the front end 2 (Step S5).
It is stored in the memory 15 in correspondence with the F data (step S6). This acquisition of each received signal level of the same network station frequency is sequentially repeated according to the AF data list until it is completed for all network station frequencies (step S7).

When the receiving signal levels for all network station frequencies have been captured, the AF data with some of the higher levels among the received signal levels stored in the memory 15 is read (step S8), and the tuning operation is performed based on this AF data. (step S9), then imports PI data representing the network of the receiving station (step 510), and determines whether or not this PI data matches the held PI data (step 511); if they match, In this case, the same network station frequency that is currently being received is set as a new reception frequency, and the mode shifts to normal reception mode.

If the PI data do not match, it is determined whether the comparison of the PI data for all network station frequencies has been completed (step 512). If not, the comparison of each received signal level stored in the memory 15 is performed. The AF data having the next highest level is read (step 513), and the operations from step 89 to Sll are repeated until it is determined in step S12 that the AF data has been completed for all network station frequencies. Then, the same network station frequency with which the PI data first match becomes the new reception frequency. P for all network station frequencies! If there is no match even after comparing the data, the AF data held is called in step S3 and the original reception frequency is returned.

In this way, the received frequency is sequentially switched to the same network station frequency based on the AF data list, the received signal level is checked, and the PI data of each received broadcast wave is changed to the PI data of the original received broadcast wave in order of the received signal level. By comparing the same network station with which the PI data first matches as a new receiving station, it is possible to select the same network station with the best reception condition.

In the above embodiment, the AF data obtained by demodulating the received broadcast waves is taken in and stored in the memory 15, but since the AF data is repeatedly sent, it is not necessarily necessary to store it in the memory 15. There is no need to keep it, AF
It is also possible to import the data when it is needed.

As described in detail, according to the reception frequency selection method according to the present invention, the reception frequency is sequentially switched to other same network station frequencies given by AF data, and the reception signal level of each reception signal is checked. The PI data of each broadcast wave is compared with the PI data of the original receiving station in descending order, and the same network station frequency with which the PI data first matches is set as the new receiving frequency.
Since you can select network stations, you can always maintain stable reception.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an RDS receiver to which the receiving frequency selection method according to the present invention is applied, and FIG. 2 is a procedure of the receiving frequency selection method according to the present invention executed by the processor in the controller shown in FIG. FIG. 3 is a diagram showing the baseband coding structure of a radio data signal, and FIG. 4 is a diagram showing the format of a type OA group. Explanation of symbols of main parts 2...Front end 4...FM detector 5...Multiplex demodulation circuit 8...Digital PLL circuit 9...Decoder 14... ...Controller applicant Pioneer Corporation

Claims (1)

[Claims] A reception frequency selection method in an RDS receiver capable of receiving RDS broadcast waves including frequency data and program identification data of the same network station group and having a function of following the same program, the method demodulating the broadcast waves of the current reception frequency. The program identification data obtained from the above program identification data is held, and the received frequency is sequentially switched to other same network station frequencies given by the frequency data to capture each received signal level, and the received frequencies are changed in descending order of the received received signal level. Switch again to the other same network station frequency, compare the program identification data obtained from each broadcast wave with the stored program identification data, and select the same network station frequency whose program identification data first matches as the new reception frequency. A reception frequency selection method in an RDS receiver, characterized in that: