JPH01177721A - Reception frequency selection method in rds receiver - Google Patents

Abstract

PURPOSE:To always obtain an accurate demodulation data and to ensure the interruption processing by an interruption data by selecting a frequency of same network excellent in a reception data. CONSTITUTION:In the standby state of TA interruption, when an unlock detection signal is consecutive for a prescribed time, a PI data and a reception frequency obtained from the existing reception broadcast wave are stored while taking it that the reception state disabling the demodulation of the data from the reception broadcast wave takes place. When a reception signal level obtained from a level detection circuit 17 is a set level or over, the signal level of the reception frequency is fetched and stored in a memory 15 corresponding to each AF data. When the PI data representing the network station of the reception station is coincident with the PI data stored in the memory 15, the station frequency of the same network during reception at present is switched to a new reception frequency.

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 (Biphasic).
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 broadcasting of the same program. Frequency (AF) of network station group
In block 4, program service name information (PS) data such as broadcasting station name and network name is arranged. Furthermore, each group is classified into 16 types, 0 to 15, using 4 bits according to its content, and two versions, A and B, are defined for each type (0 to 15), and these The recognition code is placed in block 2. Note that the AP data of the network station is transmitted only by type OA group.

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, the AF data of a group of network stations broadcasting the same program can be obtained, so this AF data can be used to check the reception status. It is possible to switch the receiving frequency to another better same network station frequency.

Furthermore, for example, in a standby state for a TA interrupt due to TA data, the TA interrupt becomes possible by demodulating the received broadcast wave and capturing the TA data, but the data from the received broadcast wave at the current reception frequency is If demodulation becomes impossible, TA data cannot be taken in, so interrupt processing using the data cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points.The present invention has been made in view of the above-mentioned points.The present invention has been made in view of the above-mentioned points. The purpose is to provide a frequency selection method.

In the receiving frequency selection method according to the present invention, in an RDS receiver capable of receiving RDS broadcast waves including AF data, PI data, and interrupt data of the same network station group, in a standby state for an interrupt due to interrupt data, the current receiving frequency is broadcast. The PI data obtained by demodulating the wave is held and RDS
When it becomes impossible to demodulate data from broadcast waves, switch the reception frequency from the current reception frequency to another same network station frequency given by AF data, and if the reception signal level exceeds the set level, the PI data matches. It is characterized in that when the same network station frequency exists, the same network station frequency is used as the new reception 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 the FM detector 4 via the 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.
The channel selection operation is performed under the control of 4. The detection output of the FM detector 4 is supplied to an MPX (multiplex) demodulation circuit 5, and in the case of stereo broadcasting, it is separated into L (left) and R (right) channel audio signals, which are then passed through a function switching circuit 19 to playback audio. This becomes the output. The function switching circuit 19 selectively outputs an audio signal from the MPX demodulation circuit 5 or, for example, the tape player 20, and the switching control is performed by the controller 14.

Further, when the detection output of the FM detector 4 passes through the filter 6, a 57 KHz subcarrier, that is, a radio data signal, amplitude modulated by the biphase coded 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. In addition, the lock detection circuit 11
An unlock detection signal is generated when an unlock occurs due to the inability to demodulate data from a received broadcast wave, and this lock error detection signal is supplied to the controller 14. In the decoder 9, the biphase coded data signal which is the demodulated output of the PLL 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.

It 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). Furthermore, the controller 14 includes a lock detection circuit 1.
When the controller 14 is supplied with this unlock detection signal, the reception condition of the broadcasting station currently being received deteriorates and data demodulation becomes impossible. In addition, based on the AF data of the same network station group stored in the memory 15 in advance, it also performs a control operation to select other same network stations.

Also, in IF amplifier 3! The level detection circuit 17 detects the received signal level (field strength) based on the F signal level, and the IF signal level in the 1F amplifier 3 is at a predetermined level or higher and the detection output of the so-called S curve characteristic in the FM detector 4 is at a predetermined level. A station detection circuit 18 that detects a receiving station when it is within the range and outputs a station detection signal is provided. The signal is provided to 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 fl+f2...fn of the same network stations as the broadcasting station currently being received. shall be taken as a thing.

The processor first determines whether the flag FA indicating that the TA interrupt standby process has ended is "11" (step Sl), and if it is FA'FI, the TA in the operation unit 16 is
Determine whether the interrupt button is on (step S2)
. If the TA interrupt button is on, for example, a TA interrupt standby process is performed to control the function switching circuit 19 to select an audio signal from the tape player 20 (step S3), and then the previous flag FA is set to "1". Thereafter, it is determined whether an unlock detection signal is generated from the lock detection circuit 11 (step S5). On the other hand, in step S1, FA
-i, it is determined whether the TA data is "1m" (step S6); if TA-1, this TA
The process shifts to data interrupt mode, and if TA'FI, the process moves to step S5.

If it is determined in step S5 that an unlock detection signal is being generated, it is determined whether or not it continues for a predetermined time (step S7), and if it continues, demodulation of data from the received broadcast wave is performed. PI data obtained from the currently received broadcast wave and its reception frequency are taken in and held in an accumulator or the like (step S8). Next, according to the AF data list, 1 AF data in the list is read from the memory 15 (step S9), and this AF data is output to a PLL circuit (not shown) in the front end 2 to perform a tuning operation (step S9). 510). Then, it is determined whether the received signal level VS obtained from the level detection circuit 17 is equal to or higher than the set level VH (step 511), and if Vs≧VH, the signal level of the received frequency is taken in and used as each AF data. The data are stored in the memory 15 in correspondence (step 512). The acquisition of received signal levels equal to or higher than the set level VH is sequentially repeated according to the AP data list until it is determined that the received signal levels of all network station frequencies have been checked (step 313). On the other hand, if VS<VH in step S11, it is determined whether or not the received signal levels of all network station frequencies have been checked (step 514); if not, the process returns to step S9 and the above-described operation is performed. repeat. If it has been completed, it is determined whether there is a reception frequency with a reception signal level equal to or higher than the set level vH (step 515), and if there is, the process moves to the next step.

After checking the received signal levels for all network station frequencies, step 516) reads out the AF data with the highest level from among the received signal levels stored in advance in the memory 15, and performs tuning based on this AF data. (Step 517), then fetches PI data representing the network station of the receiving station (Step 518), and determines whether this PI data matches the PI data held in the memory 15 ( step 519). If the PI data match, it is further determined whether the TP data is "1" or not (step 520); if the TP data is TP-1, the same network station frequency that is currently being received is set as the new receiving frequency as normal. Shift to reception mode.

If it is determined in step S19 that the PI data do not match, it is determined whether or not the PI data has been checked for all network station frequencies whose reception signal levels are stored in the memory 15 (step 521);
If not, the AF data with the next highest received signal level is read out (step 522), and the process returns to step S17 to perform a tuning operation based on the AF data.

If the check of PI data for all network station frequencies has been completed, this means that there is no reception frequency in the same network station group with a reception signal level equal to or higher than the set level Vs, so the PI data is held in step S8. AF
Recall the data and return to the original receiving frequency (step 8)
23).

If it is determined in step S20 that the received signal level is TP'lF1, it is determined whether or not the check of TP data for all network station frequencies whose reception signal levels are stored in the memory 15 is completed (step 524).
If not completed, the next AF data with the highest received signal level is read out (step 525), and the process returns to step S17 to perform a tuning operation based on the AF data.

If the TP data checks for all network station frequencies have been completed, the received signal level will reach the set level V.
Even if there is a same network station frequency equal to or higher than s, that broadcast station is not a traffic information broadcast station, so the AF data held in step S8 is called and the original reception frequency is returned (step 526).

In this way, when it becomes impossible to demodulate data from received broadcast waves in the TA interrupt standby state, by switching the reception frequency to the same network station frequency with good reception conditions, it is possible to receive data in stable reception conditions. Since accurate demodulated data can always be obtained by performing demodulation, interrupt processing using TA data can be performed reliably, and traffic information can be reliably heard. In particular, by selecting the same network station frequency with the highest received signal level, interrupt processing can be performed more reliably.

In the above embodiment, the occurrence of a reception state in which data demodulation is not possible is detected by detecting lock loss in the lock detection circuit 11. However, as another detection method, synchronization in the group and block synchronization circuit 12 may be used. It is also possible to detect the occurrence of a reception state in which data cannot be demodulated by detecting errors or data error rates.

Furthermore, in the above embodiment, the case of a TA interrupt caused by TA data, which is interrupt data, has been explained, but the present invention is not limited to this, and PTY (program ty
pe) data and M/S (susic/speech)
It is also applicable to the case of an interrupt caused by interrupt data such as switch) data. In this case, step S2
0, the processing of steps S24 to S26 is unnecessary.

As described in detail, according to the receiving frequency selection method of the present invention, when it becomes impossible to demodulate data from a received broadcast wave in an interrupt standby state, the receiving frequency is changed from the current receiving frequency to the AF data. Switch to another same network station frequency given, and if the received signal level is equal to or higher than the set level and P! When there is a same network station frequency with which data matches, by using that same network station frequency as the new reception frequency, data can be demodulated under stable reception conditions, making it possible to always obtain accurate demodulated data. Therefore, it is possible to reliably perform interrupt processing using interrupt data.

[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 detection M
5...Multiplex demodulation circuit 8...Digital PLL circuit 9...Decoder 14...Controller applicant Pioneer Corporation

Claims (2)

[Claims] (1) A reception frequency selection method in an RDS receiver capable of receiving RDS broadcast waves including frequency data, program identification data, and interruption data of the same network station group,
In the interrupt standby state due to the interrupt data, the program identification data obtained by demodulating the broadcast wave of the current reception frequency is held, and when demodulating the data from the RDS broadcast wave becomes impossible, the reception frequency is changed. Switch from the current receiving frequency to another same network station frequency given by the frequency data, and the same network whose received signal level is equal to or higher than the set level and whose program identification data obtained from that broadcast wave matches the held program identification data. A reception frequency selection method in an RDS receiver, characterized in that when a station frequency exists, the same network station frequency is set as a new reception frequency. (2) Sequentially switching the receiving frequency from the current receiving frequency to the other same network station frequency to capture the received signal level equal to or higher than the set level, and setting the same network station frequency with the maximum received signal level as the new receiving frequency. A reception frequency selection method in an RDS receiver according to claim 1, characterized in that: