JPH0879018A - Rds receiver - Google Patents

Abstract

PURPOSE: To attain efficient new broadcast station followup (NF) processing by applying the NF processing only to stations whose reception time is new in a reception history list. CONSTITUTION: A system controller 10 provides a command to a PLL circuit 2b so as to allow the circuit 2b to receive a station frequency signal fj depending on frequency data in an i-th (i:1 is set at first) address in a memory area for reception history corresponding to a network in a memory 11 corresponding to the channel selection by an operation section 12. When it is discriminated that a reception electric field strength obtained from a level detector 7 exceeds a setting level in the reception state of the station frequency fj, because it means successful reception, the reception of the received frequency signal in this case is continued. Then the memory content is shifted one by one address to store a newest reception frequency fj and a time series reception history list is formed for each network. When the received electric field strength is less than the setting level, a current variable (i) is incremented by one and then the processing is repeated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to RDS receivers.

[0002]

2. Description of the Related Art Data such as information on broadcast program contents, traffic information broadcast station identification information, and frequency information of broadcast waves transmitted from broadcast stations belonging to a broadcast network broadcasting the same program as the broadcast. Frequency-multiplexed RDS data signal containing FM is transmitted to the FM broadcast signal which is the main information signal, and the receiving side demodulates the RDS data signal to reproduce various main information based on each of these information. There is known an RDS broadcasting system which has a function.

The RDS data signal has a bit rate of 118.
7.5bps 2-phase DPSK (Differentially Encoded PS)
The K) signal, which is a 57 KHz subcarrier that is the third harmonic of the stereo pilot signal having a frequency of 19 KHz, is frequency-multiplexed outside the frequency band of the audio FM modulated wave by performing carrier suppression type amplitude modulation. As shown in FIG. 1, the data structure of the baseband of the RDS data signal is composed of 4 blocks with 104 bits as one group, and each block has 16 bits of information word and 10 bits.
26 with bit checkword and offset word
It consists of bits. The content of each information word is defined by the group type code.

Block 1 of the information words of each block
The information word is always a 16-bit program identification code (hereinafter referred to as PI code), and includes information such as country, region, and network. The information word of block 2 includes a 5-bit group type code and a 1-bit traffic information station (TP).
n) Code, 5-bit program type (PTY: Programm
e Type) code and other information is included. Block 3
And the information word of block 4 is defined by the group type determined by the group type code of block 2. If the group type is 0A, block 3
In addition, the frequency data of the network station broadcasting the same program as the current receiving station is 8-bit AF (Alternative Freq
uencies) data, the broadcast station name data for displaying the station name of the receiving station on the display in block 4 is 16-bit PS (Programme Service name) data,
Each is specified.

One of the methods of using such an RDS data signal is the network follow function. This feature
In advance, the PI code and AF data in the RDS data signal multiplexed in the received broadcast wave are demodulated and fetched, and the AF data is stored as an AF list in a predetermined area in the memory for each PI network, that is, for each broadcast network. I'll do it. Then, for example, R receiving this RDS signal
When the reception status of the broadcast wave from the receiving broadcast station deteriorates while moving in a car equipped with a DS receiver, the PI code (set PI code) of the broadcast wave received up to now from the AF list AF corresponding to the same PI code as
Each of the data is sequentially read, and another broadcasting station belonging to the same broadcasting network and capable of being well received is automatically selected so that the same broadcasting program can always be heard with a clear sound.

On the other hand, in recent years, the frequency data of the actually received receiving station are stored as reception history data for each network in an attempt to shorten the time until the completion of the selection of the alternative station in the AF list which enables good reception. Memory AF
Japanese Unexamined Patent Publication (Kokai) No. 5-199076 discloses a technique of sequentially selecting station frequencies in already stored reception history data in the search mode.

AF is performed by the memory AF search operation.
Since all stations in the list are not searched, only the broadcasting station that has once received is subjected to the following channel selection of the same program broadcasting station, that is, the memory network follow operation (hereinafter referred to as memory NF operation). , N
The tuning operation in the F operation can be executed in a short time.

By the way, when attention is paid to one automobile, a relatively short-distance daily traveling area in which the automobile frequently travels and a relatively long-distance quasi-daily traveling in which the automobile travels, for example, about once a month. It is possible to consider three types of driving areas: an area and an extraordinary driving area where the vehicle runs for the first time. Then, for example, when the automobile is in the daily driving area, it is considered that more efficient NF operation can be obtained by executing the memory NF operation for a relatively limited number of AF stations.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to classify the traveling areas of a single automobile into different traveling areas. An object of the present invention is to provide an RDS receiver capable of performing efficient memory NF operation.

[0010]

SUMMARY OF THE INVENTION An RDS receiver according to the present invention multiplexes a main information signal and an RDS data signal containing a station frequency list of alternative stations belonging to the same network as the main information signal. RDS receiver capable of receiving the RDS broadcast wave, the reception frequency storing means storing the first predetermined number of station frequencies of the actually received broadcast station for each network and in the order of the reception time. Of the station frequencies stored in the history storage means, a designation means for designating only a second predetermined number of station frequencies smaller than the first predetermined number from the later reception time for each network, and the designation means R based on the list of the selected station frequencies, and a tuning means for performing a follow-up tuning operation in the same network.
It is a DS receiver.

[0011]

According to the RDS receiver of the present invention, the NF operation based on the received frequency history data or the NF operation only on the limited frequency data in order from the newest one in the received frequency history data is performed. Accordingly, the NF operation will be performed only for the station frequencies that are highly likely to be selected.

[0012]

The present invention will be described in detail below with reference to the drawings. FIG. 2 is a schematic block diagram showing the basic configuration of the RDS receiver according to the embodiment of the present invention. In the figure,
The FM broadcast wave in which the RDS data signal received by the antenna 1 is multiplexed is converted to an intermediate frequency (IF) with a frequency of 10.7 MHz by selecting a radio wave of a desired broadcast station in the front end 2, and the IF amplifier 3 Is amplified by. The front end 2 includes the mixer 2a and the PLL circuit 2
b with a programmable frequency divider (not shown)
A local oscillator signal to the mixer 2a is obtained by the PLL synthesizer method using the LL path 2b, and the tuning operation of the programmable frequency divider is controlled by the controller 10 which will be described later to perform a channel selection operation. ing.

An FM signal of 10.7 MHz amplified by the IF amplifier 3 and sufficiently suppressed in amplitude is demodulated into an audio signal by an FM detector 4, and an L (left) channel in the case of stereo broadcasting by a stereo demodulation circuit 5. And R (right) channel audio signals are separated and output as reproduced audio signals through the muting circuit 6. Also,
A level detector 7 that detects a received signal level (electric field strength) based on the IF signal level in the IF amplifier 3, and the received signal level is equal to or higher than a predetermined level and FM.
There is provided a station detector 8 which outputs a station detection signal indicating that a receiving station is detected when the detection output of the S-shaped curve characteristic in the detector 4 is within a predetermined level range.

Further, from the detection output of the FM detector 4, RDS
An RDS signal detector 9 for detecting a data signal is provided, and R output from the RDS signal detector 9 is provided.
The DS data, the received signal level output from the level detector 7, and the station detection signal output from the station detector 8 are all supplied to the system controller 10 having a microcomputer configuration.

The controller 10 includes an information word of each block in the RDS data signal input in group units,
That is, the PI code, AF data, PS data, etc. are fetched and stored in the memory 11. The memory 11 serves as a storage unit that stores, for each network, alternative frequency data (AF data) representing a frequency of a broadcast signal belonging to the network as an AF list. In addition, based on a tuning command accompanied by a reception frequency from the operation unit 12 or based on AF data read from the AF list at the time of network follow-up, the frequency division ratio of the programmable frequency divider constituting the front end is set. By controlling, a desired broadcast station or another broadcast station of the same network as the broadcast station being received is selected. Also, it outputs a switching signal for turning on the muting circuit 6 at the time of tuning. Operation unit 12
The display unit 13 and the display unit 13 are provided on the front panel of the RDS receiver. The display unit 13 displays the network corresponding to the designated channel as a result of the automatic channel selection processing such as network follow (that is, the network to be selected).
The system controller 10 is responsible for notifying that the network identification data for identifying the network, that is, the PI code, is not received and that the broadcast of the network corresponding to the designated channel cannot be received.
The display is made in accordance with the display control signal from.

The specific structure of the RDS signal detector 9 is shown in FIG. In FIG. 3, the detection output of the FM detector 4 passes through the filter 14 and is amplitude-modulated by the biphase-coded data signal.
Hz subcarrier, that is, RDS signal component is extracted and P
It is demodulated by the LL circuit 15. This demodulated output is supplied to the digital (D) PLL circuit 16 and the decoder 17. The D-PLL circuit 16 generates a data demodulating clock based on the demodulated output of the PLL circuit 15. The generated clock is supplied to the gate circuit 18. The lock detection circuit 19 detects that the D-PLL circuit 16 is locked, generates a lock detection signal, supplies the lock detection signal to the gate circuit 18, and controls the circuit 18 to be in an open state. In the decoder 17, the PLL circuit 15
The bi-phase coded data signal, which is the demodulation output of, is decoded in synchronization with the clock generated by the D-PLL circuit 16.

The output data of the decoder 17 is composed of four blocks of 26 bits 104 as shown in FIG.
It is a group unit series of bits and is sequentially supplied to the block group synchronization & error detection circuit 20. In the block group synchronization & error detection circuit 20, 1 of each block
1 assigned to each 0-bit checkword
Block group synchronization is performed based on the 0-bit offset word, and error detection of the 16-bit information word is performed based on the check word. Then, the data in which the error is detected is error-corrected by the error correction circuit 21 in the next stage and then supplied to the controller 10.

However, control signals are supplied to the circuits 20 and 21 from the system controller 10, respectively.
The output data of the decoder 17 is kept as it is under the control of the system controller 10 as will be described later, and therefore the RDS in which each synchronization and error detection / correction are not performed.
It may be output as received data. In the RDS receiver having such a configuration, the system controller 10 receives the reception frequency data value that determines the frequency division ratio of the programmable frequency divider of the PLL circuit 2b in response to the user's tuning operation (or channel recall) of the operation unit 12. A channel selection operation is performed by controlling.

If a broadcast wave from one broadcast station A belonging to a network is selected and the broadcast wave is received, a signal indicating the signal level of the received radio wave is obtained from the level detector 7. Also, station detection signals are obtained from the station detector 8, and these signals are supplied to the system controller 10. P from the RDS data signal
Data such as I code, AF data, PS data is RDS
It is taken in by the system controller 10 via the signal detection unit 9 and written in the memory 11. In addition, a predetermined storage area of the memory 11 belongs to a network to which the broadcasting station A transmitting the currently received broadcast wave belongs.
The history station frequencies f1, f2, ..., Fn of the respective broadcast waves transmitted by the individual broadcast stations are stored as a normal AF list. This situation is shown in the table of FIG. In the table, PI ₁ , P
I ₂ ... Is PI data representing each network,
The addresses ADD ₁ , ADD ₂ , ... Are addresses for accommodating the frequencies of each station.

Further, according to the present invention, the operation unit 12 is provided with a key (not shown) for inputting a mode command for determining a mode of the NF processing described below. Each mode of daily running, semi-daily running and non-daily running can be specified prior to running the vehicle. The designated traveling mode is stored in a predetermined storage area (address) of the memory 11.

Next, an example of the NF processing subroutine executed by the system controller 10 in this RDS receiver will be described with reference to the flowchart of FIG. The NF processing subroutine SR1 shown in FIG. 5 is executed by interrupting the main routine in the system controller 10 formed by a so-called microcomputer. First, in step S1, operation is performed via the operation unit 12. It is determined whether or not the mode command already given by the person and stored in the memory 11 is the non-daily running mode. When it is determined in step S1 that the current designated traveling mode is the non-daily traveling mode, the normal NF processing subroutine SR2 is executed according to the AF list given by the RDS data signal (step S2).

The normal NF processing subroutine SR2 is well known and will not be described in detail here. Step S
When it is determined in 1 that the current designated traveling mode is not the non-daily traveling mode, the variable i is set to 1 (step S2), and it is determined whether the currently designated traveling mode is the semi-daily traveling (step S31). .

When it is determined in step S3 that the currently designated traveling mode is the quasi-daily traveling mode, the frequency data fj is added to the add _i- th address in the reception history memory area corresponding to a certain PI in the memory 11. (J:
As soon as any one of 1 ... n exists, it is determined (step S4). When it is determined in step S4 that the frequency data fj exists, a command is given to the PLL circuit 2b so as to receive the station frequency fj determined by the frequency data fj at the i-th address (step S5).

Then, information on the received electric field strength obtained from the level detector 7 in the receiving state of the station frequency fj is obtained, and it is judged as soon as the present received electric field strength exceeds the set level (step S6). In step S6,
When it is determined that the received electric field strength exceeds the set level, the reception is successful, so the contents of the miss counter corresponding to the add _i address are reset to zero (step S
7) The reception of the reception frequency at this time is continued (step S8).

After that, a time series history list creation subroutine SR3 described later is executed. On the other hand, when it is determined in step S6 that the received electric field strength is less than or equal to the set level, the data value in the miss counter area corresponding to the add _i address is incremented by one (step S9), and then the variable i is added. The current value of is incremented by 1 and step S11 is entered (step 10). Step S11
If it is determined that the variable i is equal to or smaller than the first predetermined maximum value imax1, the process returns to step S4.
When> imax1 is determined, it is determined that the NF processing in the semi-daily running mode has not succeeded, and the NF processing subroutine by the AF list shown in FIG. 4, that is, the normal NF processing subroutine SR2 is executed.

If it is determined in step S4 that the frequency data fj does not exist at the add _i address, the process jumps to step S10. On the other hand, when it is determined in step S3 that the current traveling mode designated via the operation unit 12 is not the quasi-daily traveling mode, it can be said that the designated traveling mode is the daily traveling mode. accessing the add _i-th address in the history list, which frequency data fj is determined there as soon as (step S12). If it is determined that the frequency data fj exists at the add _i address,
The PLL circuit 2b is instructed to receive the signal of the frequency fj of the address d _i (step S13). Then, it is determined whether or not the received electric field strength at this time is higher than the set level (step S16).

If it is determined in step S16 that the received electric field strength is higher than the set level, add
_The miss counter memory value corresponding to the _i- th address is reset to zero (step S17), and the reception is continued as it is (step S18). On the other hand, when it is determined in step S16 that the received electric field strength is equal to or lower than the set level, the miss count memory value corresponding to the addi address is incremented by 1 (step S1
9) and then replace the variable i with i + 1 (step S2
0), the obtained value of i is the second predetermined maximum value imax2 (i
As soon as max2> imax1) is exceeded, it is determined (step S21). In step S21, i ≦ i
When it is determined that the value is max2, step S12
When it is determined that i> imax2, the normal NF processing subroutine SR2 based on the AF list in FIG. 4 is executed.

Next, the time-series reception history list creation subroutine SR3 will be described with reference to FIG. In this subroutine SR2, n is first set to 1 (step S20), and the same frequency as the latest reception frequency fj is stored in the address add _{n of the} same PI in the time series reception history list area in the memory 11. Whether or not it is determined is determined (step S21). In step S21,
If it is determined that such a frequency exists, add
The memory contents of _n are deleted (step S22), and the addresses smaller than add _n , that is, the memory contents of add ₁ to add _n-1 are shifted one by one to the old number (step S23). And
The latest reception frequency fj is stored in add ₁ (step S2)
4).

On the other hand, when it is determined that the station frequency equal to the latest reception frequency fj does not exist in add _n , n
Is replaced with n + 1 (step S25) to obtain n
Is determined to be greater than nmax (step S
26). When n <nmax is determined in step S26, the process returns to step S21, and when n ≧ nmax is determined, the memory contents of add ₁ to add _n are moved to the old address (that is, the rear address) by one address (step S27). ), And then executes step S24.

By executing the above-mentioned subroutine SR3, the time-series reception history list as shown in FIG. 7 is formed for each PI, that is, for each network. Next, a sub-routine SR4 for deleting the station frequency with many reception failures from the time-series reception history list and shortening the processing time of the NF processing based on the time-series reception history list will be described with reference to FIG.

In this subroutine, first, the variable i is set to 1 (step S30), and the miscount value of the address add _i is compared with the predetermined value Cmax (step S30).
31). When it is determined in step S31 that the miscount value of add _i exceeds Cmax, the memory content of add _i is deleted (step S32). Then i> im
As soon as ax is determined (step S33), i ≦
If it is imax, i is replaced by i + 1 (step S34) and the process returns to step S31. When it is determined in step S33 that i> imax, the subroutine SR4 is ended and the process returns to the main routine.

When it is determined in step S31 that the miscount value does not exceed Cmax, step S32 is skipped and the process jumps to step S33. In the above-described embodiment, if the operator does not specifically specify the traveling mode, the system controller 10
However, the daily running mode may be prioritized.

[0033]

As is apparent from the above description, in the RDS receiver according to the present invention, the reception history of the actually received RDS broadcasting stations is stored for a predetermined number of stations to create the reception history list. Since the NF process is performed only for the station with the newest reception time in the list, if the vehicle travels within the range of short-distance daily movement, all stations in the reception history list Since NF processing is not performed on frequencies but only on station frequencies with a high probability of successful reception, efficient NF processing corresponding to the running mode of the vehicle can be performed.

[Brief description of drawings]

FIG. 1 is a baseband RDS data configuration diagram.

FIG. 2 is a block diagram showing a basic configuration of an RDS receiver according to the present invention.

3 is a block diagram showing a specific configuration of an RDS signal detector of the RDS receiver shown in FIG.

FIG. 4 is a table showing a normal AF list.

FIG. 5 is a flowchart showing the NF processing function of the RDS receiver according to the present invention.

FIG. 6 is a flowchart showing a time-series reception history list creation subroutine in the flowchart of FIG.

7 is a table showing a time-series reception history list formed by the subroutine of FIG.

8 is a flowchart showing a subroutine for deleting a station frequency with a large number of reception failures from the time-series reception history list of FIG.

[Explanation of symbols]

 1 antenna 2 front end 2a mixer 2b PLL circuit 3 IF amplifier 4 FM detector 5 stereo demodulation circuit 6 muting circuit 7 level detector 8 station detector 9 RDS signal detector 10 system controller 11 memory 12 operation unit 13 display unit 14 Filter 15 PLL 16 D-PLL 17 Decoder 18 Gate 19 Lock Detector 20 Block Group Synchronization and Error Detection Circuit 21 Error Correction Circuit

Claims (3)

[Claims] 1. An R multiplexed with a main information signal and an RDS data signal including a station frequency list of alternative stations belonging to the same network as the network to which the main information signal belongs.
An RDS receiver capable of receiving a DS broadcast wave, the reception history storage unit storing a first predetermined number of station frequencies of actually received broadcast stations for each network and in order of the reception time, and the reception history. Of the station frequencies stored in the storage means, a designation means for designating only a second predetermined number of station frequencies smaller than the first predetermined number from the later reception time for each network, and the designation means An RDS receiver comprising: a tuning unit that performs a tracking tuning operation in the same network based on a list of station frequencies. 2. The RDS receiver according to claim 1, wherein the designation means is deactivated according to a command. 3. The RD according to claim 2, wherein the command is a semi-daily running or non-daily running mode command.
S receiver.