DE19531367A1 - RDS receiver - Google Patents

Description

The invention relates to a radio data system (RDS) receiver ger.

Description of the related art

An RDS transmission method is known in which an RDS data signal with data such as information regarding program content ten of a shipment, identification (ID) information of a traffic information sending station, frequency information of a broadcasting world le, which is generated by a transmitter station, which to a Belongs to the broadcasting network, which broadcasts the same program content det, and the like into an FM broadcast signal as a main formation signal is frequency multiplexed, the resulting Signal is transmitted, the RDS data signal on the reception side is demodulated and numerous functions other than the reproduction of the main information signal on the basis of the received information are provided.

The RDS data signal is a DPSK (differentially coded PSK-) signal with two phases, in which a bit rate is the same Is 1187.5 bps and a subcarrier of 57 kHz as one third harmonic of a stereo pilot signal of a frequency of 19 kHz amplitude modulated after carrier suppression is so that the modulated signal is out of band half of a frequency band of a frequency-modulated audio Wave is frequency multiplexed.  

A data structure of a baseband of the RDS data signal, as shown in Fig. 1, consists of four blocks in which 104 bits are set into a group, and each block consists of 26 bits, which is composed of an information word of 16 bits and a check word and an offset word of 10 bits are constructed. The contents of each information word are specified by a group type code.

An information word from block 1 in the information word of each block is always a program identification code (hereinafter referred to as a PI code) with 16 bits, and includes information such as nation, district and network. An information word from block 2 includes information such as group type code of five bits, traffic program identification (TP) code of one bit and program type (PTY) code of five bits. Information words from blocks 3 and 4 are specified by a group type, which is determined by the group type code of block 2 . Further, in the case of group type OA, frequency data of a network station which transmits the same program as the station currently being received is specified in block 3 as AF (alternative frequency) data of eight bits, or transmit station name data to a station name of received station on a display are specified in block 4 as PS (program service name) data of 16 bits.

One of the application methods of such an RDS data signal nals is a network follow-up function. According to this function who the PI code and the AF data in the RDS data signal are multiplexed to the received transmission wave, demodulated and read, and the AF data is preparatively as one AF list in a predetermined area in a memory saved for each PI code, namely the transmission network. If For example, a received state of the received Transmitting wave from the transmitting station during the movement a car deteriorates in which an RDS receiver is turned on  is built to receive the RDS signal, each of the AF data corresponding to the same PI code as the PI code (set PI code) of the transmission wave that was received is, successively read from the AF list, and another Broadcasting station belonging to the same broadcasting network and can preferably be received, is automatically switched off selects, allowing the same broadcast program can always be heard with a clear sound.

The past few years has been disclosed in the Japanese Patent Application Kokai No. 5-199076 discloses a technique been in the order of time to complete the Selection of an alternative station, which is preferred can be received from the AF list to shorten the Receive station frequency data which is actually received were saved as reception history data for each network and in the memory AF search mode, the stations frequencies in the reception history data, which already have been saved can be selected one after the other.

Not all stations in the AF list are identified by one searched such memory AF search mode, but only regarding the transmitting station which has already received once a subsequent station selection will be the same Program sending station, namely a storage network operation (hereinafter simply referred to as a memory NF operation) executed, so that the station selection operation in NF operation can be executed in a short period of time.

When a car is viewed, it is possible to drive three realm types to take into account, namely a daily driving area over a relatively short distance in which the Car drives frequently every day, a half-day driving area over a relatively long distance in which the car for example, drives about once a month and one does not  daily driving area, in which the car for the first time moves.

For example, if the car is in the daily driving area is taken into account that a more effective NF-Be drive can be obtained by the memory NF operation regarding a relatively limited number of AF stations is performed.

Summary of the invention

The present invention is made in consideration of the above Points, and it is an object of the invention to achieve one To create RDS receivers, in which in the case where Driving ranges of a car are classified as effective Storage NF operation in every driving range can be.

According to the present invention there is an RDS receiver seen who can receive an RDS transmission wave through Multiplexing a main information signal and an RDS Data signal is obtained, the station frequency list alternative stations belonging to the same network, like a network to which the main information signal belongs, includes, wherein the RDS receiver includes receive stratified storage means, for each network and according to the Order from the previous reception time, only a first one predetermined number of station frequencies from one broadcast station that was actually received, Label means to add from the previous reception time each network only a second predetermined number of stations frequencies less than the first predetermined Number of station frequencies that are in the receive range layer storage means are stored, to designate, and Station selection means to a subsequent station selection operation  in the same network based on a list of station fre Execute sequences by the label are designated.

According to the RDS receiver of the invention, the NF operation through the reception frequency history data or the NF-Be only the new data is received frequency history data executed so that the NF operation with regard to only the station frequency with a high possibility station selection according to a driving range of driving witness is running.

Brief description of the drawings

The invention is exemplified below with reference to Described drawing, in which shows:

Fig. 1 is a diagram showing the organization of the RDS data to a baseband,

Fig. 2 is a block diagram showing a fundamental construction of an RDS receiver according to the OF INVENTION dung,

Fig. 3 is a block diagram showing a specific construction of an RDS Signaldetektierabschnitts of the RDS receiver of Fig. 2,

Fig. 4 is a table that shows an ordinary AF list,

Fig. 5 is a flow chart showing functions of the NF-processing, which of the RDS receiver according to the invention,

FIG. 6 is a flowchart showing a subroutine to form a time series reception history list in the flowchart of FIG. 5;

FIG. 7 is a table showing a time series reception history list formed by the subroutine of FIG. 6, and

FIG. 8 is a flowchart showing a subroutine to clear station frequencies in which the number of times that reception fails is deleted from the time series reception history list of FIG. 6.

Detailed description of the preferred embodiment

The invention will now be described in detail below with reference to FIG the drawing described.

Fig. 2 is a schematic block diagram showing a basic structure of an RDS receiver of an embodiment according to the invention.

In the diagram, among FM transmission waves received by an antenna 1 and multiplexed by an RDS data signal, a radio wave of a desired transmission station in a front end 2 is selected and converted to an intermediate frequency (IF) of 10.7 MHz and in one IF amplifier 3 amplified. The front end 2 has a mixer 2 a and a PLL circuit 2 b and receives a local oscillation signal to the mixer 2 a through the PLL synthesizer system, which uses the PLL circuit 2 b, which includes a programmable frequency divider (not shown) . The station selection operation is carried out by controlling a frequency division ratio of the programmable frequency divider by a controller 10 , which will be explained below.

The FM signal of 10.7 MHz, which was amplified in the IF amplifier 3 , and the amplitude of which was sufficiently suppressed, is demodulated into an audio signal by an FM detector 4 . In the case of stereo broadcasting, the audio signal is separated into audio signals of the L (left) and R (right) channels in a stereo demodulation circuit 5 . The audio signals of the L and R channels are output as reproduced audio signals via a mute circuit 6 .

The RDS receiver also includes a level detector 7 to detect a received signal level (field intensity) based on an IF signal level in the IF amplifier 3 , and a station detector 8 to output a station detection signal which indicates the detection of a received station when the received signal level is equal to or higher than a predetermined level and a detection output with S-shaped curve characteristics in the FM detector 4 is in a predetermined level range.

An RDS signal detection section 9 is also provided to detect an RDS data signal from a detection output of the FM detector 4 . RDS data generated by the RDS signal detection section 9 , a reception signal level generated by the level detector 7 , and a station detection signal generated by the station detector 8 are supplied to the system controller 10 with a microcomputer structure.

The controller 10 takes information words from each block in the RDS data signal input on a group unit basis, namely a PI code, AF data, PS data and the like, and stores them in a memory 11 . The memory 11 serves as a storage means to store alternative frequency data (AF data) indicating a frequency of a transmission wave belonging to a network as an AF list for each network. By controlling the frequency division ratio of the above programmable frequency divider that forms the front end 2 , based on a station selection command accompanied by a reception frequency from an operation section 12 , or on the basis of the AF data that is from the AF list at the time the network sequence are read out, a desired transmission station or another transmission station of the same network is selected as the transmission station which is received. A switching signal is generated in order to switch on the mute circuit 6 when selecting the station. The operating section 12 and a display section 13 are provided on a front panel of the RDS receiver. In the case where network identification data (PI code) to identify a network (namely, the network to be selected) corresponding to a designated channel is not detected as a result of the automatic station selection process, such as a network sequence, the display section 13 acts as a reporting means to report that the broadcast of the network cannot be received according to the designated channel. The display section 13 displays a message according to a display control signal from the system controller 10 .

Fig. 3 shows a specific structure of the RDS signal detection animal section 9 .

Since the detection output of the FM detector 4 runs through a filter 14 , an amplitude-modulated subcarrier with 57 kHz, according to a bi-phase coded data signal, namely an RDS signal component in a PLL circuit 15, is extracted and demodulated according to FIG . A demodulated output is fed to a digital (D) PLL circuit 16 and a decoder 17 . The D-PLL circuit 16 generates a clock for data demodulation based on the demodulated output of the PLL circuit 15 . The generated clock is fed to a gate circuit 18 . A latching detection circuit 19 detects that the D-PLL circuit 16 is latched, and generates a latching detection signal and leads it to the gate circuit 18 , thereby controlling that the gate circuit 18 opens. In the decoder 17 , the bi-phase coded data signal, such as a demodulated output of the PLL circuit 15 , is decoded synchronously with the clock generated by the D-PLL circuit 16 .

As shown in Fig. 1, the output data of the decoder 17 consists of a group unit row of 104 bits with four blocks each consisting of 26 bits. They are successively fed to a block group sync & error detection circuit 20 . The block group sync & error detection circuit 20 executes block group synchronization based on an offset word of 10 bits assigned to each of a check word of 10 bits in each block, and also detects an error of an information word of 16 bits based on the test word. The error-detected data are error-corrected in an error correction circuit 21 in the next stage and then supplied to the controller 10 .

Control signals are supplied by the system controller 10 to the circuits 20 and 21, respectively. There is a case in which the output data of the decoder 17 is generated as it is, corresponding to RDS reception data, which are not subjected to synchronization or error detection / correction as necessary, by a control operation of the system controller 10 , such as is explained below.

In the RDS receiver with such a structure as mentioned above, the system controller 10 controls a receive frequency data to control the frequency division ratio of the programmable frequency divider of the PLL circuit 2 b according to the station selection operation (or the channel recall) of the operation section 12 by the user determine where to run through the station selection operation.

Now, assuming that a particular station is selected with respect to a broadcast wave from a broadcast station A belonging to a certain network, and such a broadcast wave is received, a signal indicating a signal level of the received radio wave is obtained from which Level detector 7 obtained, and a station detection signal is obtained from the station detector 8 . These signals are supplied to the system controller 10 . In the RDS data signal, data such as PI code, AF data, PS data, etc. are read by the system controller 10 via the RDS signal detection section 9 and written into the memory 11 . Historical station frequencies f1, f2,. . . , fn of the transmission waves transmitted by transmission stations belonging to the network to which the transmission station A belongs, which transmits the transmission wave currently being received, are stored as an ordinary AF list in a predetermined storage area in the Memory 11 saved. Such a state is shown in a table in FIG. 4. In the diagram, PI₁, PI₂,. . . PI data showing each network. Addresses ADD₁, ADD₂,. . . display addresses to adjust each station frequency.

According to the invention, a key (not shown) is provided for the operating section 12 to enter a mode command and thus determine a mode of NF processing, which will be explained below. Each of the modes of the daily trip, the half-day trip and the non-daily trip can be designated by the mode command key before the trip of the vehicle. The designated driving mode is stored in a predetermined memory area (address) in the memory 11 .

An example of the NF processing subroutine executed by the system controller 10 in the RDS receiver will now be described with reference to a flow chart of FIG. 5.

An NF processing subroutine SR1 shown in FIG. 5 is executed while the main routine is being interrupted by the system controller 10 , which consists of a microcomputer. First, in step S1, a check is made to see whether or not the mode command already issued by the operator through the operation section 12 and stored in the memory 11 indicates the non-daily driving mode. In step S1, when it is judged that the currently designated driving mode is the non-daily driving mode, an ordinary NF processing subroutine SR2 is executed according to the AF list which is output by the RDS data signal (step S2).

Since the ordinary NF processing subroutine SR2 is well-known is known, it is not described in detail here.

In step S1, if it is discriminated that the current designated driving mode is the non-daily driving mode, a variable (i) is set to 1 (step S2) and a test is performed to see if the current signed driving mode is the half-day driving mode or not (step S3).  

In step S3, when it is judged that the currently designated driving mode is the half-day driving mode, a check is made to see if frequency data f _j (j: one of 1 to n) in an address add _{i of} the memory area for one Reception history exist or not, corresponding to a certain PI in the memory 11 (step S4).

In step S4, if it is judged that the frequency data f _j are present, b issuing a command to the PLL circuit 2 to receive the station frequency f _j, which is the frequency data _j f in the address add _i determined (Step S5).

Subsequently, information of a reception field intensity output from the level detector 7 in the reception state of the station frequency f _{j is} obtained, and a check is made to see whether or not the current reception field intensity exceeds a predetermined level (step S6). In step S6, if it is different that the current reception field intensity exceeds the predetermined level, since this means that reception is successful, the contents of an error counter corresponding to the address add _{i are} reset to 0 (step S7). In this case, reception of the current reception frequency is continued (step S8).

Thereafter, a time series reception history list forming subroutine SR3 is executed, which will be explained below. In contrast, when it is judged in step S6 that the reception field intensity is equal to or lower than the predetermined level, a data value of a miss counter area corresponding to the address add _{i is increased} only by "1" (step S9). The current value of the variable (i) is increased only by "1" and step S11 follows (step S10). In step S11, when it is judged that the variable (i) is equal to or less than a first predetermined maximum value i _max1 , the processing _routine is returned to step S4. However, when i <i _{max1 is} judged, it is considered that the LF processing fails in the half-day driving mode, so that the LF processing subroutine through the AF list shown in FIG. 4, namely the ordinary LF processing subroutine SR2 is performed.

In step S4, if it is judged that the frequency data f _j does not exist in the address add _i , the processing routine jumps to step S10.

In step S3, if it is judged that the current driving mode designated by the operation section 12 is not the half-day driving mode, it means that the designated driving mode is the daily driving mode. The controller therefore accesses address add _i in the time series reception history list and checks to see if the frequency data f _j is present there or not (step S12).

If it is judged that the frequency data f _{j is present} in the address add _i , the PLL circuit 2 b is instructed to receive the frequency f _j in the address add _i (step S13). A check is made to see whether or not the reception field intensity is greater than the predetermined level at this time (step S16).

In step S16, when it is judged that the reception field intensity is larger than the predetermined level, the value of the miss count memory corresponding to the address add _{i is} reset to 0 (step S17). Reception continues as it is (step S18).

On the other hand, in step S16, when it is judged that the reception field intensity is equal to or lower than the predetermined level, the value of the miss count memory corresponding to the address add _{i is} only increased by "1" (step S19). Subsequently, the variable (i) is replaced by (i + 1) (step S20). A check is made to see whether or not the resulting value of (i) exceeds a second predetermined maximum value i _max2 (i _max2 <i _max1 ) (step S21). In step S21, if it is judged that ii is _max2 , the processing _routine is returned to step S12. When it is judged that i <i _max2 , the ordinary NF processing _subroutine SR2 is executed based on the AF list in FIG. 4.

The time series reception history list forming subroutine SR3 will now be described with reference to FIG. 6.

In the subroutine SR2, (n) is first set to 1 (step S22). In the time series reception history list area in the memory 11 , a check is made to see whether or not the same frequency as the latest reception frequency f _{j has} been stored in an address add _{n of} the same PI (step S23). In step S23, if it is judged that the same frequency is present, the memory contents in the address add _{n-1 are} cleared (step S24). The memory contents in addresses smaller than the address add _n , namely add₁ to add _n-1 are shifted to larger addresses, namely an address by one (step S25). The latest reception frequency f _j is stored in the address add₁ (step S26).

On the other hand, if a distinction is made that a station frequency equal to the latest reception frequency f _{j is} not present in the address add _n , (n) is replaced by (n + 1) (step S27). A check is made to see whether the resultant (n) is larger than n _max or not (step S28). If it is judged in step S28 that n <n _max , the processing routine is returned to step S23. If it is judged that nn is _max , the contents of the memory are shifted into the addresses add 1 to add _n to larger (namely, following) addresses, namely an address by one (step S29). Then step S26 is carried out.

By executing the previous subroutine SR3, the time series reception history list as shown in Fig. 7 is formed at every PI, namely every network.

Now, a subroutine SR4 will be described with reference to Fig. 8 to clear station frequencies in which the number of times that reception fails is large from the time series reception history list and a processing period for the NF processing shrink based on the time series receiving history list.

In the subroutine, the variable (i) is first set to 1 (step S30). An erroneous count in an address add _i is compared with a predetermined value C _max (step S31). In step S31, when it is judged that the miss count value in the address add _i C _max exceeds, the memory contents in add _{i are} cleared (step S32). Subsequently, a check is made to see whether i <i _max or not (step S33). If ii is _max , (i) is replaced by (i + 1) (step S34). The processing routine is returned to step S31. In step S33, when it is judged that i <i _max , the subroutine SR4 is ended, and the processing routine is returned to the main routine.

If it is judged in step S31 that the miss count does not exceed C _max , the processing routine jumps to step S33 without executing step S32.

In the above embodiment, unless the operator specifically designates the driving mode, the system controller 10 may preferably set the daily driving mode.

In the RDS receiver of the invention, the reception stories the RDS broadcasting stations that were actually received, only fed by a predetermined number of stations saves, the reception history list is formed, and the LF processing is only the latest in terms of station Receiving time executed in such a list. In the case, in which the vehicle is traveling in the short range, in which the vehicle drives every day is therefore the NF-Verar processing carried out with regard to the station frequencies, at which the probability of successful reception is high, rather than NF processing in terms of all To run station frequencies in the reception history list Ren. The effective NF processing according to the Fahrzu the vehicle can therefore be carried out.

RDS receiver, in which only a first predetermined number of station frequencies of RDS transmission waves, which actually received for each network, and according to the order of an earlier reception time and among the station frequencies that are saved according to a command only a second predetermined number of stations frequencies less than the first predetermined Number of times each network received earlier are, and based on a list of designated Sta tion frequencies, a subsequent station selection operation in the same Network is running. The next station selection operation can consequently be carried out in terms of station frequencies  in which a way that the station is selected is high according to a driving range of a vehicle, so that a period of time required for a subsequent station selection processing is required, can be downsized.

Claims (3)

1. RDS receiver capable of receiving an RDS transmission wave by multiplexing a main information signal and an RDS data signal including a station frequency list of alternative stations belonging to the same network as a network to which the main information signal belongs, is obtained, which includes
Reception history storage means for storing, for each network and according to the order of an earlier reception time, only a first predetermined number of station frequencies of RDS transmission waves which have actually been received;
Designation means for designating, from the previous reception time from each network, only a second predetermined number of station frequencies which is smaller than the first predetermined number of the station frequencies stored in the reception history storage means; and
Station selection means for executing a subsequent station selection operation in the same network on the basis of a list of the station frequencies which are designated by the designation means. 2. RDS receiver according to claim 1, wherein the designation medium is not activated according to a command. 3. RDS receiver according to claim 2, wherein the command half-day driving mode command or a non-daily- Driving mode command is.