JP2571270B2 - Radio data receiver - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radio data system receiver (hereinafter referred to as RD).
S receiver).

BACKGROUND ART When a broadcast station broadcasts, broadcast-related information such as information related to the program content is transmitted as data by multiplex modulation, and a desired program content can be selected on the receiving side based on the demodulated data. Radio data system (RD
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 this case, a radio data signal is obtained by vibration-modulating a data signal indicating information related to broadcasting, such as the contents of a program, and the sub-carrier subjected to sub-modulation is frequency-modulated to a main carrier for broadcasting.

As is clear from FIG. 4 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 is composed of four blocks each having a 26-bit configuration, and each block is composed of a 16-bit information word and a 10-bit check word. In FIG. 5, block 1 broadcasts a program recognition (P1) code representing a network, block 2 broadcasts a traffic program identification (TP) code or traffic announcement identification (TA) code, and block 3 broadcasts the same program. Station frequency (AF) data of the network station in question, and program service name information (PS) data such as a broadcast station name and a network name are arranged in the block 4, respectively. In addition, each group is of type 0 to 15 with 4 bits according to its contents.
And two versions of A and B are defined for each type (0 to 15), respectively, and these codes are arranged in block 2. The station frequency (hereinafter abbreviated as AF) data of the network station is transmitted only in the type OA group, and the program service name information (hereinafter abbreviated as PS) data is transmitted in the type OA and OB groups. Has become.

The TP code is arranged in the block 2 of each group, and is a 1-bit code indicating whether or not the broadcast wave transmits traffic information. That is, when the TP code is logic “0”, the broadcast wave does not transmit traffic information.
If the code is logic "1", it is a broadcast wave for transmitting traffic information. The TA code is also a one-bit code, and when transmission of traffic information is actually started, a logical "1" is set.
When the transmission of the traffic information ends, the logic becomes "0".
Therefore, if the RDS broadcast wave having the logic "1" is simply received and the audio output is not performed as a standby state by interrupting the TA code to make the audio audible, for example, during the listening of music by the tape player, It is possible to automatically switch to the traffic information listening state.

By the way, in the case of an in-vehicle receiver, the reception state of a broadcast wave being received may be deteriorated due to multipath interference or a received electric field strength as the vehicle travels. It is considered that the state shifts from the interrupt standby state to the interrupt state, and during the interrupt processing after the shift, the reception state deteriorates, so that it becomes impossible to accurately demodulate the data from the received broadcast wave at the current reception frequency. If accurate demodulation of data becomes impossible as described above, the interrupt processing will malfunction.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a radio data receiver which prevents a malfunction of an interruption process when a reception state of a received broadcast is deteriorated in an interruption state.

A radio data receiver according to the present invention includes: a demodulation unit that performs radio data demodulation of a radio data broadcast wave that includes, as radio data, interrupt data indicating broadcast or stop of a specific program content; Interrupt start detection for detecting that the obtained interrupt data indicates the broadcast of the specific program content when the interrupt data is obtained from the demodulation means in the interrupt standby mode in which the output is cut off and waiting for the start of the specific program content Means and an interrupt mode for changing the audio output of the radio data broadcast wave being received from the interrupted state to the audible state when the interrupt data indicates the broadcast of a specific program content by the interrupt start detecting means. And interrupt data obtained when interrupt data is obtained from the demodulation means in the interrupt mode. An interrupt end detecting means for detecting that the broadcast of the specific program content is stopped, and an interrupt standby mode is executed when the interrupt end detecting means detects that the interrupt data indicates the end of the broadcast of the specific program content. A radio data receiver comprising: a mode setting unit; and performing an interrupt standby mode when a state in which radio data cannot be demodulated in the interrupt mode continues for a predetermined time or more.

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

In FIG. 1 showing an example of the configuration of an RDS receiver according to the present invention, an FM multiplex broadcast wave received by an antenna 1 is selected by a front end 2 and converted into an intermediate frequency (IF). The signal is supplied to the FM detector 4 via the IF amplifier 3. The front end 2 obtains a local signal to the mixer 2b by a PLL synthesizer method using a PLL circuit 2a including a programmable frequency divider, and the frequency division ratio of the programmable frequency divider is controlled by a controller 14 to be described later. By doing so, 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 L (left) and R (right) channel audio signals in the case of a stereo broadcast, and reproduced via a function switching circuit 19. Audio 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 its 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 _Z subcarrier whose amplitude is modulated by the biphase-coded data signal, that is, a radio data signal is extracted and demodulated by the PLL circuit 7. You. This demodulated output is supplied to a digital (D) PLL circuit 8 and a decoder 9.
Supplied to 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 detection circuit 11 detects that the D-PLL circuit 8 has locked, generates a lock detection signal, and supplies this to the gate circuit 10 to control the circuit 10 to open. Further, the lock detection circuit 11 generates an unlock detection signal when an unlock occurs due to the inability to demodulate data from the received broadcast wave, and the unlock detection signal is supplied to the controller 14. . The decoder 9 decodes the biphase-coded data signal, which is the demodulated output of the PLL circuit 7, 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 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.

The group / block synchronization & error detection circuit 12 synchronizes the group with the block based on the 10-bit offset word assigned to the 10-bit check word of each block, and 16-bit information based on the check word. Word error detection is performed. Then, the error-detected data is supplied to a controller 14 as data processing means after the error is corrected by an error correction circuit 13 at the next stage.

The controller 14 is constituted by a microcomputer, and the code information of each block in the radio data sequentially inputted in the group unit, that is, the radio data information (the PI data and the AF data described above) related to the program contents of the broadcasting station currently being received. , PS data, etc.) and store them in the memory 15, and determine the frequency division ratio of the programmable frequency divider of the PLL circuit 2 a constituting a part of the front end 2 based on a channel selection command from the operation unit 16. The tuning operation is performed by controlling the reception frequency data value. Further, an unlock detection signal is supplied to the controller 14 from the lock detection circuit 11 as a demodulation possibility determination unit,
When the unlock detection signal is supplied, the controller 14 determines that the reception state of the currently receiving broadcast station has deteriorated and the data cannot be demodulated.

Further, a level detection circuit 17 for detecting a reception signal level (electric field strength) based on the IF signal level in the IF amplifier 3.
And a station detection circuit for outputting a station detection signal assuming that a broadcast wave has been received when the IF signal level in the IF amplifier 3 is equal to or higher than a predetermined level and the detection output of so-called S-curve characteristics in the FM detector 4 is within a predetermined level range. The station detection signal output from the station detection circuit 18 and the received signal level detected by the level detection circuit 17 are supplied to the controller 14.

The memory 15 is a non-volatile RAM (not shown) in which data such as reception frequency data, PI code, and AF data is written, and an RO in which programs and data are written in advance.
M (not shown).

Next, the processing operation executed by the processor of the controller 14 will be described with reference to the flowchart shown in FIG.

The processor repeatedly executes the normal mode routine at a predetermined timing, and executes the interrupt mode routine when the interrupt mode is set. First, in normal mode, TA
Flag indicating that an interrupt waiting process is finished is F _A "1"
Is determined (step 51). If F _A ≠ 1, it is determined whether a TA interrupt button (not shown) on the operation unit 16 has been operated (step 52). When the TA interrupt button is operated, for example, a function switching circuit for selecting an audio signal from the tape player 20
Performs a TA interrupt wait process that controls step 19 (step 5
3), followed by "1" is set to the flag F _A (Step 5
4) Wait for TA interrupt. Thereafter, it is determined whether or not the content of the TP code in the data obtained from the currently received RDS broadcast wave is logic "1" (step 55).
If the TP code is logic "1", it means that an RDS broadcast wave for broadcasting traffic information has been received, and it is further determined whether or not the content of the TA code in the data is logic "1" (step 56). TA
If the code is logic "1", the broadcast of traffic information is started or is being broadcast, so that the mode immediately shifts to the interrupt mode. If the TP code is logic “0”, the broadcast wave for broadcasting the traffic information is not received. If the TA code is logic “0”, the broadcast of the traffic information is not started. In these cases, the processing of this routine is temporarily terminated.

On the other hand, if F _A = 1 in step 51, it is in the TA interrupt waiting state, so it is determined whether or not the TA interrupt waiting should be reset (step 57). For example, a flag F _A to release the reset TA interrupt wait state 0 if TA interrupt reset button in the operation unit 16 (not shown) has been operated (step 58). If it is not necessary to reset the TA interrupt wait, the process proceeds to step 55 to determine whether to enter the interrupt mode.

In the interrupt mode, it is determined whether or not an unlock detection signal is generated from the lock detection circuit 11 as shown in FIG. 3 (step 61). If no unlock detection signal has been generated, it is determined whether or not the TA interrupt wait should be reset (step 62). If it is not necessary to reset the TA interrupt wait, the reception process is performed by the interrupt reception process for controlling the function switching circuit 19 to select the audio signal from the MPX demodulation circuit 5 even during tape reproduction (step 63). Then, it is determined whether or not the content of the TA code in the data is logic "1" (step 64).
If the TA code is logic "1", the flow returns to step 61 because the traffic information is being broadcast, and the above operation is repeated. If the TA code is logic "0", the traffic information has been broadcasted and the TA interrupt is awaited. Processing is performed (step 65), the interrupt mode is terminated, and the mode returns to the normal mode in the interrupt standby state.

If TA interrupt waiting to be reset condition to reset the flag F _A 0 releases the TA interrupt waiting state (Step 6
6) Exit the interrupt mode and return to the normal mode.

On the other hand, if it is determined in step 61 that the unlock detection signal has been generated, it is determined that it has been detected for a predetermined time t (for example,
10 seconds) or not (Step 6)
7). If the unlock detection signal has not been continuously generated for a predetermined time t or more, the process proceeds to step 63 to continue the interrupt processing. Assuming that a receiving state where demodulation of the data signal cannot be performed has occurred, the process proceeds to step 65 to end the interrupt mode and return to the normal mode in the interrupt standby state.

Thus, in the TA interrupt state, when it becomes impossible to demodulate the data from the received broadcast wave, it takes a predetermined time t.
If the above is continued, the process returns to the interrupt waiting state, and the malfunction of the interrupt process due to the data that has not been accurately demodulated is prevented.

In the above embodiment, the occurrence of a reception state where data cannot be demodulated is detected by detecting the loss of lock in the lock detection circuit 11. However, as another detection method, the synchronization in the group / block synchronization circuit 12 is performed. It is also possible to detect the occurrence of a reception state in which data cannot be demodulated by detecting a deviation or an error rate of data.

Further, in the above embodiment, TA is used as the interrupt data.
Although the description has been given of the case of the TA interrupt by data, the present invention is not limited to this, and is applicable to an interrupt by interrupt data such as PTY (Program type) data or M / S (music / speech switch) data. is there.

Effect of the Invention As described above, according to the radio data receiver of the present invention, the interruption state, that is, the interruption standby state when the demodulation of the received broadcast wave becomes impossible for a predetermined time or more in the interruption mode. That is, since the process returns to the interrupt standby mode, it is possible to prevent a malfunction of the interrupt process due to incorrect demodulated data. Further, even if data demodulation becomes impossible, the apparatus does not immediately return to the interrupt standby state, so that the so-called fluttering that reciprocates between the interrupt states and the interrupt standby state can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an RDS receiver according to the present invention, FIGS. 2 and 3 are flowcharts showing the procedure of a processing operation executed by a processor in a controller shown in FIG. 1, and FIG. FIG. 5 is a diagram showing a baseband coding structure of a data signal, and FIG. 5 is a diagram showing a format of a type OA group. Description of main parts 2... Front end, 4... FM detector 5... Multiplex demodulation circuit 8... Digital PLL circuit 9... Decoder, 14.

Claims (1)

(57) [Claims] 1. A demodulating means for demodulating radio data of a radio data broadcast wave including, as radio data, interrupt data indicating a broadcast or a stop of a broadcast of a specific program content; When the interrupt data is obtained from the demodulation means in an interrupt standby mode for waiting for the start of the specific program content, an interrupt start for detecting that the obtained interrupt data indicates the broadcast of the specific program content Detecting means, when the interrupt start detecting means detects that the interrupt data indicates the broadcast of the specific program content, changes the audio output of the radio data broadcast wave being received from the interrupted state to the audible state. Processing means for executing an interrupt mode, wherein the interrupt data is obtained from the demodulation means in the interrupt mode. Interrupt end detecting means for detecting that the obtained interrupt data indicates the broadcast stop of the specific program content; and that the interrupt data indicates the broadcast end of the specific program content by the interrupt end detecting means. And a mode setting means for executing the interrupt standby mode when is detected, the radio data receiver comprising: A radio data receiver for executing an interrupt standby mode.