JP2965725B2 - Control method of RDS receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a radio data system receiver (hereinafter referred to as an RDS receiver).

[0002]

2. Description of the Related Art When a broadcast station broadcasts, broadcast-related information such as information related to the contents of the program is transmitted as data by multiplex modulation, and the data is demodulated on the receiving side based on the demodulated data. There is a radio data system (RDS) in which the contents of a program can be selected and the service can be provided to a radio listener.

In this radio data system, F
Outside the frequency band of the M-modulated wave, 57 KHz, which is the third harmonic of the stereo pilot signal of 19 KHz, is used as a subcarrier, and this subcarrier is filtered and biphasic.
(Biphase) The radio data is amplitude-modulated by a data signal indicating information related to the broadcast such as the program contents coded.
The sub-carrier whose amplitude has been modulated is frequency-modulated to the main carrier and broadcast.

[0004] The radio data signal, as is apparent from FIG.
The bits are repeatedly multiplexed and transmitted as one group. 1
Each group is composed of four blocks each having a 26-bit structure, and each block is composed of a 16-bit information word and a 10-bit check word. In FIG. 6, block 1 includes a program recognition (P) representing a network.
I) code, block 2 is a traffic program recognition (TP) code or traffic announcement recognition (TA) code, and block 3 is the frequency of a network station group broadcasting the same program. (AF) data, and program service name information (PS) data such as a broadcast station name and a network name are arranged in the block 4, respectively. Each group is classified into 16 types of types 0 to 15 with 4 bits according to the contents, and two versions of A and B are defined for each type (0 to 15). These recognition codes are arranged in block 2. The AF data of the network station is transmitted only through the type 0A group,
Data is transmitted in type 0A and 0B groups.

In the case of an in-vehicle receiver, the reception state of a broadcast wave being received may deteriorate as the vehicle travels. Therefore, when one RDS broadcast is received, the broadcast of the same program is performed as described above. Since it is possible to obtain AF data of a group of network stations performing the above, it has been desired that a broadcast program of the same network can be listened to in a good reception state by utilizing the AF data. Therefore, AF data of a group of network stations broadcasting the same program is stored in a memory in advance, and the electric field strength of the received RDS broadcast wave falls below a set level for a predetermined time or more. Then, one AF data of the same network station group broadcasting the same program is selectively read out from the memory and actually received at the frequency indicated by the AF data, and the set level is set. The same program follow-up operation that immediately shifts to the reception of the RDS broadcast wave when the RDS broadcast wave having the above-mentioned electric field strength can be received is disclosed in JP-A-64-55916 and is already known.

[0006] For example, in a tunnel, a specific R among a group of network stations broadcasting the same program is designated.
In some cases, only broadcast waves from DS broadcast stations can be received,
Therefore, when the vehicle enters the tunnel during actual traveling, the radio wave from the RDS broadcasting station which has been received until then becomes almost unreceivable, and in such a case, the same program following operation is started. However, if the received signal level of the RDS broadcast wave that can be received in the tunnel is lower than the set level, the same program follow-up operation is always performed. Is interrupted and it is very hard to hear. In order to cope with this, at the frequency received by the AF data of the same network station group stored in the memory, if any of the RDS broadcast waves has a received signal level lower than the set level, the same program following operation is performed. Is stopped for a predetermined time. However, when the same program following operation is stopped for a predetermined time,
Even if another RDS broadcast wave that broadcasts the same program through the tunnel can be received at a sufficient signal level, the same program following operation is not immediately started, so that the bad reception state is continued. This can be considered not only when traveling in a tunnel but also when traveling in mountainous areas.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an RD which can quickly shift to the reception of RDS broadcast waves which can obtain a good reception condition even when traveling in a tunnel or mountainous area.
An object of the present invention is to provide a control method of the S receiver.

[0008]

According to the present invention, there is provided a method for controlling an RDS receiver, comprising: a first step of detecting an average level of a received signal level of a currently received broadcast wave within a predetermined time for each predetermined timing; When the average level exceeds the predetermined value and falls below a second predetermined value that is smaller than the first predetermined value,
Alternatively, a second step of generating a frequency check signal when the previous average level is lower than the second predetermined value and the current average level is higher than the first predetermined value, and a broadcast station of the currently received broadcast wave according to the frequency check signal Selectively reads out from the memory one frequency data of the group of network stations to which
And a third step of switching the reception frequency to the frequency indicated by the read one frequency data.

[0009]

According to the control method of the RDS receiver of the present invention, for example, when a vehicle enters or exits a tunnel, the reception signal level of the current reception broadcast wave decreases, and the previous reception signal level is reduced. If the current average level falls below the second predetermined value even if the average level of the current broadcast wave exceeds the first predetermined value, the frequency data of one of the network stations to which the broadcasting station of the currently received broadcast wave belongs is assigned. Data is selectively read from the memory, and switching of the reception frequency to the frequency indicated by the read one frequency data is started. Therefore, at the frequency received by the frequency data of the same network station group stored in the memory, any RDS
If the broadcast wave is also at a received signal level lower than the set level, the reception of the current received broadcast wave is continued, and the A stored in the memory unless the received signal level of the current received broadcast wave changes significantly.
The same program tracking operation of actually receiving another broadcast wave and detecting the received signal level by the F data is not repeated. Further, when the vehicle passes through the tunnel, the received signal level of the currently received broadcast wave increases, so that even if the previous average level of the received signal level is lower than the second predetermined value, the current average level becomes the first predetermined level. If the value exceeds the value, one frequency data of the network station group to which the broadcasting station of the currently received broadcast wave belongs is selectively read from the memory, and the frequency indicated by the read one frequency data is read. The switching of the receiving frequency is started. Therefore, it is possible to quickly shift to the reception of the RDS broadcast wave of the frequency at which a better reception state can be obtained.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the RDS receiver to which the control method of the present invention shown in FIG.
After a desired station is selected by the front end 2 and converted into an intermediate frequency (IF), the M multiplex broadcast wave is converted into an IF amplifier 3
Is supplied to the FM detector 4 via the. Front end 2
Is obtained by a PLL synthesizer system using a PLL circuit 2a including a programmable frequency divider, and a frequency division ratio of the programmable frequency divider is controlled by a controller 14 described later. Thus, a channel selection operation is performed. The detection output of the FM detector 4 is supplied to an MPX (multiplex) demodulation circuit 5, where it is separated into audio signals of L (left) and R (right) channels in the case of stereo broadcasting.

When the detection output of the FM detector 4 passes through the filter 6, a 57 KHz subcarrier amplitude-modulated by the bi-phase coded data signal, that is, a radio data signal is extracted. PLL circuit 7
Is demodulated. As the PLL circuit 7, for example,
The circuit disclosed in Japanese Patent Publication No. 3-87052 is used.
The demodulated output from the PLL circuit 7 is a digital (D) P
It is supplied to the LL circuit 8 and the decoder 9. In the D-PLL circuit 8, a clock for data demodulation is generated based on the demodulated output of the PLL circuit 7. The generated clock is supplied to the gate circuit 10. The lock detecting circuit 11 is disclosed in, for example, JP-A-63-87039 and JP-A-63-8763.
040, which detects that the D-PLL circuit 8 is locked, generates a high-level lock detection signal, detects the unlock state of the D-PLL circuit 8, and outputs a low-level lock detection signal. Generates unlock detection signal. The output signal of the lock detection circuit 11 is supplied to the gate circuit 10 to
Control to open the gate circuit 10 when the PLL circuit 8 is unlocked. The output signal of the lock detection circuit 11 is supplied as a lock range switching signal for switching and controlling the lock range of the PLL circuit 7 and the D-PLL circuit 8, and the lock detection circuit 10 outputs the signal to the D-PLL.
When the lock state of the circuit 8 is detected, the lock range of the PLL circuit 7 and the D-PLL circuit 8 is narrowed so that the clock for data demodulation is always supplied as a stable clock without being affected by the outside. I have to. In the decoder 9, a bi-phase coded data signal which is a 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. 5, the output data of the decoder 9 is a 104-bit group consisting of four blocks each having a 26-bit structure. It is supplied to the detection circuit 12. In the group / block synchronization & error detection circuit 12, one of each block
1 assigned to each 0-bit check word
The group and the block are synchronized based on a 0-bit offset word, and an error detection of a 16-bit information word is performed based on a check word. The detected data is error-corrected by an error correction circuit 13 at the next stage, and then supplied to a controller 14.

The controller 14 is constituted by a microcomputer, and is related to the code information of each block in the radio data which is sequentially inputted in units of groups, that is, the program information of the broadcast station currently being received. Radio data information (such as the PI code, AF data, and PS data described above) is fetched and stored in the memory 15. By this operation, an AF data list (AF data f (1), f (2)... F (n)) of the same network station as the currently received broadcast station is formed.
Also, based on a channel selection command from the operation unit 16, a reception frequency data which determines a frequency division ratio of a programmable frequency divider (not shown) of the PLL circuit 2a constituting a part of the front end 2 is described.
The tuning operation is performed by controlling the data value. The reception frequency data value is, for example, a count value of a counter.

On the other hand, the level detection circuit 19
The received signal level (electric field strength) is detected based on the IF signal level at. In addition, the station detection circuit 20 determines that the IF signal level in the IF
When the detection output of the so-called S curve characteristic in the detector 4 is within a predetermined level range, a station detection signal is output. Each output signal of the level detection circuit 19 and the station detection circuit 20 is supplied to the controller 14.

The memory 15 stores reception frequency data, P
It consists of a nonvolatile RAM in which data such as I-code and AF data is written, and a ROM in which programs and data are written in advance. Next, the operation of the processor of the controller 14 showing the procedure of the control method of the present invention will be described with reference to FIG.
4 will be described with reference to the flowchart shown in FIG.

When the processor detects that the same program follow button (not shown) of the operation unit 16 has been operated, the processor enters the same program follow mode, and the AF checker shown in FIGS. -Run the chin. In the AF check routine, the processor first resets the measured value T of the timer to an initial value (for example, 0) (step S1), and resets both the AF check trigger flag FTR and the PI search request flag FRQ to 0. (Step S
2). The timer is formed by executing steps S1, S4, S6 and the like. After the execution of step S2, the variable m is made equal to 1 (step S3), the measured value T of the timer is increased by the unit time T1 (step S4), and the received signal level Vs output from the level detection circuit 19 is fetched. It is stored in the memory 15 as Vs (m) (step S5), and it is determined whether or not the measured value T of the timer overflows (step S6). That is, it is determined whether or not the measured value T of the timer has reached the set time TMAX. If T <TMAX, 1 is added to the variable m (Step S7), and the routine goes to Step S4. Although not shown, if T <TMAX, step S4 is executed after determining the elapse of the unit time T1.

If T ≧ TMAX in step S6,
The average level VAV of the received signal levels Vs (1), Vs (2),..., Vs (m) is calculated (step S8). That is, the received signal levels Vs (1), Vs (2),..., Vs (m) are read from the memory 15 and added to obtain a total value, which is divided by the value of the variable m at that time. After calculating the average level VAV, the previous average level VAV is read as VAV-1 (step S
9) It is determined whether or not the average level VAV is smaller than a predetermined value VL (second predetermined value) (step S10). VAV <
If it is VL, it is determined whether or not the previous average level VAV-1 is larger than a predetermined value VH (first predetermined value) (step S).
11). The predetermined value VH is larger than the predetermined value VL. VAV-1
If> VH, the PI search request flag FRQ is set to 1 (step S12), and the AF check trigger flag FTR is set.
Is set to 1 (step S13), and the current average level VAV is stored in the memory 15 (step S1).
4). Even if VAV <VL, in step S11, VAV-1 ≦
If it is determined to be VH, the process proceeds to step S14. In addition,
The setting of 1 to the flag FTR generates a frequency check signal.

If VAV≥VL in step S10, it is determined whether or not the average level VAV is greater than a predetermined value VH (step S15). If VAV> VH, it is determined whether or not the previous average level VAV-1 is smaller than a predetermined value VL (step S16). If VAV-1 <VL, the process proceeds to step S13, where the AF check trigger flag FTR
Is set to 1. Step S1 even if VAV ≧ VL
If it is determined in step 5 that VAV ≦ VH, the process proceeds to step S14. Further, even if VL≤VAV≤VH, step S16 is executed.
Also, when it is determined that VAV-1 ≧ VL, the process proceeds to step S14.

After execution of step S14, it is determined whether or not the AF check trigger flag FTR is equal to 1 (step S17). If FTR = 1, the variable u is made equal to 1 (step S19), and A is written in the memory 15.
Each AF data f (1), f (2)... F in the F data list
One AF data f (u) is read from (n) and set in the frequency divider of the PLL circuit 2a (step S20). As a result, the reception frequency changes to the broadcast frequency of another broadcast station of the same network as the current reception broadcast station (the broadcast station that was received immediately before entering the same program tracking mode). Next, AF data
The received signal level Vs at a new reception frequency based on the AF data f (m) of one of the list is fetched (step S).
21) It is determined whether or not the received signal level Vs is higher than the set level V1 (step S22). In addition,
Although not shown, after the time from when the AF data is set by execution of step S20 until the reception frequency is stabilized, step S21 is executed. Vs ≤ V1
If so, it is determined whether or not the variable u has reached the number n of AF data in the AF data list (step S23). If u <n, 1 is added to the variable u (step S24), and the process proceeds to step S20. By repeating this operation, each AF data f (1), f (2)... F in the AF data list
AF data from which a received signal level of Vs> V1 is obtained from (n). That is, if Vs> V1 in step S22, the received frequency data in the memory 15 is updated with the AF data f (u) in order to maintain the receiving state (step S25), and this routine is executed. finish. Therefore, the broadcast wave is received at the frequency based on the AF data f (u). That is, a broadcast wave that broadcasts the same program as the currently received broadcast wave received immediately before the same program follow-up mode and has a received signal level higher than the set level V1 is received, and a broadcast station of that frequency is newly added. Current broadcasting station,
The same program tracking mode ends. If u = n, the reception signal level has been checked in step S22 for all AF data f (1), f (2)... f (n), and the process proceeds to step S26 to be described later. .

In step S26, it is determined whether or not the PI search request flag FRQ is equal to one. If FRQ = 0, the AF data broadcasting the same program as the current receiving broadcasting station
There is no other broadcast station that can obtain a received signal level of Vs> V1 and there is no need for a PI search. Therefore, the current received broadcast wave that was received immediately before the same program tracking mode was entered. In order to return to the reception, the reception frequency data in the memory 15 is read out and set in the frequency divider of the PLL circuit 2a (step S27). The receiving state of the currently received broadcast wave received just before the same program tracking mode is set, and this routine ends to shift from the same program tracking mode to the normal reception mode. If FRQ = 1, the PI search operation is started. That is, the reception frequency data of the current reception broadcasting station in the memory 15 is read out as search frequency data (step S29), and the value of the search frequency data is set to a predetermined number (for example, 100 KHz as the reception frequency). Minute) (step S30). The search frequency data
When the value of the data exceeds the value corresponding to the upper limit frequency in the reception band, it becomes equal to the value corresponding to the lower limit frequency. Then, it is determined whether or not the search frequency data is equal to the reception frequency data of the current reception broadcasting station (step S3).
1). If the search frequency data is not equal to the reception frequency data of the current receiving broadcasting station, the search frequency data is PLL-locked.
It is set in the frequency divider of the circuit 2a (step S32), and it is determined whether or not a station detection signal is generated from the station detection circuit 20 (step S33). Although not shown, after the time from when the AF data is set by execution of step S32 until the reception frequency is stabilized, step S33 is executed. If the station detection signal has been generated, the received signal level Vs is fetched (step S34),
It is determined whether the received signal level Vs is higher than the set level V1 (step S35). If Vs> V1, it is determined whether or not the search-received broadcast wave is an RDS broadcast wave (step S36). Whether it is an RDS broadcast wave or not can be determined by whether or not various data can be obtained from the error correction circuit 12. If it is an RDS broadcast wave, the PI code of the search received broadcast wave is fetched (step S).
37), read the PI code of the currently received broadcast station from the memory 15 (step S38), and check whether the PI code of the search received broadcast wave matches the PI code of the current received broadcast station. Is determined (step S39). If the PI codes match, the reception frequency data in the memory 15 is updated with the search frequency data in order to maintain the reception state (step S40), and the routine ends. . Therefore, the service
A broadcast wave is received at a frequency based on the single frequency data.
That is, a broadcast wave that broadcasts the same program as the currently received broadcast wave received immediately before the same program follow-up mode and has a received signal level higher than the set level V1 is received, and a broadcast station of that frequency is newly added. The current receiving broadcasting station becomes the current receiving broadcasting station, and the same program following mode ends with the search operation.

If it is determined in step S33 that the station detection signal has not been generated, V is determined in step S35.
If s ≦ V1, if it is determined in step S36 that it is not an RDS broadcast wave, or if P
If it is determined that the I codes do not match, step S
Then, the process goes to 30 to increase the value of the search frequency data by a predetermined number and repeat the above operation. Step S
If it is determined in step 31 that the search frequency data has become equal to the reception frequency data of the current reception broadcasting station, the search is performed.
Vs
Since the RDS broadcast wave whose PI code coincides with the PI code of the current receiving broadcast station could not be received at the reception signal level of> V1, the process proceeds to step S27 and immediately before the same program tracking mode is set. In order to return to the reception of the currently received broadcast wave, the reception frequency data in the memory 15 is read out and the PLL is read out.
It is set in the frequency divider of the circuit 2a.

It is to be noted that the same program follow-up mode is not shown during a period in which the reception frequency has changed to a frequency based on the frequency data of the AF data list or the search frequency data other than the frequency of the current reception broadcasting station. The mute circuit operates to cut off the output of the audio signal, and the mute state is released when the same program following mode ends. In the above-described embodiment of the present invention, one of the AF data lists AF
If the received signal level Vs is higher than the set level V1 by the data, the state immediately shifts to the receiving state of the one AF data, and the same program follow-up mode ends.
Received signal level V for all AF data
s, the AF data from which the highest received signal level Vs is obtained and which is higher than the set level V1 are extracted, the state shifts to the reception state by the extracted AF data, and the same program tracking mode is performed. May be ended.

Further, in the above embodiment of the present invention, the frequency data of the same network station group is stored in the memory by obtaining the AF data from the RDS broadcast wave being received. The frequency data of the same network station group for each receivable broadcasting station may be stored in a memory in advance.

[0024]

As described above, in the control method of the RDS receiver according to the present invention, the average level of the reception signal level of the current reception broadcast wave within a predetermined time is detected at every predetermined timing, and the previous average level is set to the first level. 1 When the average level is lower than a second predetermined value that is smaller than the first predetermined value and exceeds the first predetermined value, or when the previous average level is lower than the second predetermined value and the current average level is lower than the first predetermined value. When the frequency exceeds the frequency, one frequency data of the network station group to which the broadcast station of the current reception broadcast wave belongs is selectively read from the memory, and the reception frequency is switched to the frequency indicated by the read one frequency data. Is done. As a result, unless the received signal level of the currently received broadcast wave changes significantly, the same program tracking operation of actually receiving another broadcast wave based on the frequency data stored in the memory and detecting the received signal level is performed. No. That is, the same program following operation is not repeated even if the received signal level of the currently received broadcast wave is kept below the set level, so that the reception frequency does not change, so that the program becomes very difficult to listen to. Is prevented. Therefore, the same program follow-up operation is started at an appropriate time even when traveling in a tunnel or in a mountainous area, and it is possible to quickly shift to reception of an RDS broadcast wave capable of obtaining a good reception state.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an RDS receiver to which a control method according to the present invention is applied.

FIG. 2 is a flowchart showing an AF check routine.

FIG. 3 is a flowchart showing a continuation of the AF check routine shown in FIG. 2;

FIG. 4 is a flowchart showing a continuation of the AF check routine of FIG. 3;

FIG. 5 is a diagram showing a base band coding structure of a radio data signal.

FIG. 6 is a diagram showing a format of a type 0A group.

[Description of Signs of Main Parts]

 REFERENCE SIGNS LIST 1 antenna 2 front end 4 FM detector 5 multiplex demodulation circuit 8 digital PLL circuit 9 decoder 14 controller

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuhiro Kamiya 25-1 Nishimachi, Yamada-shi, Kawagoe-shi, Saitama Prefecture Pioneer Corporation Kawagoe Factory (56) References JP-A-1-55916 (JP, A) JP-A JP-A-1-55919 (JP, A) JP-A-1-55920 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H03J 7/18 H04B 1/16

Claims (3)

(57) [Claims] 1. A method for controlling an RDS receiver comprising a memory storing frequency data of the same network station group, comprising: determining an average level of a received signal level of a currently received broadcast wave within a predetermined time; A first stroke detected at each timing, when the previous average level exceeds the first predetermined value and the current average level falls below a second predetermined value smaller than the first predetermined value, or when the previous average level is A second step of generating a frequency check signal when the current average level is below the second predetermined value and the present average level is above the first predetermined value; and a broadcast station of the current reception broadcast wave belongs according to the frequency check signal. A third step of selectively reading one frequency data of the network station group from the memory, and switching a reception frequency to a frequency indicated by the read one frequency data. A method of controlling an RDS receiver. 2. In the third step, if the reception signal level at the switched reception frequency is higher than a set level, the reception state is continued, and if the reception signal level is lower than the set level, a new frequency data is obtained. Read the data,
If the received signal level is equal to or lower than the set level at the frequency indicated by all the frequency data of the same network station group, the state returns to the reception state of the current received broadcast wave in the first step. 2. The method for controlling an RDS receiver according to item 1. 3. In the second step, a previous average level exceeds a first predetermined value, and a current average level exceeds the first predetermined value.
In the case where the frequency check signal is generated when the frequency is lower than a second predetermined value smaller than a predetermined value, in the third step, the reception signal level is at the frequency indicated by all the frequency data of the same network station group. If the received signal level is equal to or lower than the set level, the received signal level is equal to or higher than the set level while the received frequency is swept, and the program identification code obtained from the received broadcast wave matches the program identification code of the current received broadcast wave. 2. The method of controlling an RDS receiver according to claim 1, wherein