JPH05199076A - Automatic tracking method for rds radio receiver - Google Patents

Abstract

PURPOSE:To obtain excellent tracking without tracking mistake even in an area in which tracking mistake takes place by the automatic tracking according to an AF list. CONSTITUTION:The reception memory mode is set for a prescribed block from a start point till an object point in an area in which tracking mistake takes place by the automatic tracking according to an AF list. In the memory mode, a controller 13 stores history data FC1 with a frequency received by the automatic racking according to the AF list to a memory 13a. After the storage of the reception frequency history data FC1, when the memory AF search is commanded, the controller decides the tuning frequency according to the reception frequency history data every time the reception state is deteriorated to make tracking a broadcast station whose reception state is excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RDS radio receiver automatic tracking method, and more particularly to an RDS automatic tracking method effective in an area where it is difficult to receive the same P1 station.

[0002]

2. Description of the Related Art In a car radio, when a car moves out of the service area of a receiving broadcast station, re-selection is required each time. For this reason, recently, in addition to being able to easily obtain traffic information, there is a demand for more sophisticated tuning functions. In particular, FM broadcasting, which has a relatively small service area, is the main body of radio broadcasting services, and there is a strong demand for this in Europe where the ratio of car radio reception is high. Therefore, in order to meet such demands,
DS (Radio Data System) has been proposed and is being put to practical use. This RDS is a method of superimposing various digital data on an FM radio broadcast signal. As a message, (1) program (broadcast program) identification data of the currently received FM broadcast (P1) (2) broadcasting station name (PS) (3) Broadcasting station frequency list during same program broadcasting (AF) (4) Program content identification data (PTY) (5) Transmission status identification data (DI) (6) Music or conversation identification data (M / S data) and (7) Traffic information broadcasting station identification data (TP data) (8) Traffic information broadcasting identification data (TA data). The above (1) to (6) are information related to the channel selection function, and (7) and (8) are traffic information.

Thus, the FM received by the RDS is
Since messages about broadcasting are broadcast in multiplex,
By using this message, an exceptional tuning operation that has never been possible becomes possible. For example, the frequency data (AF list) of the same program broadcasting station is demodulated, and the received electric field strength is checked by sequentially tuning to each AF station on the AF list. AF that can
You can always listen to a good broadcast by tuning to the frequency of the station. (Called automatic tracking)

[0004]

When the RDS automatic tracking operation is performed, in a region where broadcasting stations of different networks are adjacent to each other, the broadcasting station of a network different from the broadcasting network which has been received up to now may be followed. .. For example, if the frequency in the AF list of the RDS data transmitted from the broadcasting station currently being received is the same as the frequency of the broadcasting station of the adjacent network and the reception electric field strength of the broadcasting station of the adjacent network is the maximum, Moved to a broadcast station on a different network and received it for a few seconds. For this reason, this is a serious problem for those who are in a daily movement area (for example, a commuting road) where the tracking error occurs. FIG. 5 is an explanatory diagram of the above-mentioned problem. The circles are the same program broadcasting stations consisting of stations A, B, and C of a certain network NW1, and the black circle D is a broadcasting station of a different network NW2. 90.1MHz, B station 90.2
MHz, C station, and D station are broadcast at the same frequency of 90.3 MHz. For those who move between adjacent broadcasting stations, as shown by the curve CV in the figure,
The RC section will always have the above-mentioned problems. For example, if the vehicle that is initially receiving station A enters the RC section and the reception status deteriorates, the same program broadcasting station with a good reception status is searched according to the AF list. During this search, the D station is received while trying to receive the C station.
Even if the D station is received, since the PI data is different from the one currently being received, the broadcasting station of the original network will be received after a few seconds.

In view of the above, the object of the present invention is to provide a broadcasting station that finally performs automatic follow-up according to the AF list once in a region where a follow-up error occurs when the normal automatic follow-up operation according to the AF list is performed. It is an object of the present invention to provide an automatic tracking method for an RDS radio receiver that can maintain a good reception state by leaving a history of reception frequencies as data and then receiving based on the data.

[0006]

SUMMARY OF THE INVENTION In the present invention, the above-mentioned problem is solved by: means for automatically following the AF list; means for recording a frequency received in a certain section as received frequency history data; and moving for that section. In this case, it is achieved by means for performing an automatic follow-up operation based on the above data.

[0007]

[Operation] Performs automatic tracking based on the AF list in a certain section,
The frequency received in the section is left as received frequency history data, and when moving in the same section, an automatic tracking operation is performed based on the data. In this way, even in an area where adjacent networks are mixed, good reception can be performed without following the broadcasting stations of different networks.

[0008]

1 is a block diagram of the essential parts of a radio receiver for realizing an automatic tracking operation according to the present invention. Reference numeral 1 is an antenna, and 2 is a front end, which tunes to a predetermined broadcasting station based on a voltage signal output from a PLL circuit described later to generate an intermediate frequency signal. An intermediate frequency amplifier 3 amplifies the intermediate frequency signal converted by the front end 2. 4 is a stereo demodulation circuit (MPX),
The intermediate frequency signal input from the intermediate frequency amplifier 3 is demodulated into a stereo signal. Reference numeral 5 is a mute circuit, 6 is an amplifier (AMP), and 7 is a speaker, which is driven by the amplifier 6 and outputs sound.

8 is a 57 KHz bandpass filter (B
PF), which passes a 57 KHz subcarrier whose amplitude is modulated based on RDS data. Reference numeral 9 denotes an RDS decoder / clock reproduction circuit, which demodulates RDS data from the output of the bandpass filter and reproduces the clock. Reference numeral 10 denotes a group synchronization / error detection / error correction circuit, which detects an error in the RDS data demodulated by the RDS decoder / clock recovery circuit 9 while synchronizing each group and corrects the error.

A signal meter 11 detects the reception level (reception electric field strength) of the reception station by monitoring the signal strength of the intermediate frequency signal output from the intermediate frequency amplifier 3. Reference numeral 12 denotes a station detector, which determines that a receiving station exists (there is a station) when the received signal is within the frequency deviation f (bandwidth) of the received signal and the signal strength is equal to or higher than a set level. ..

Reference numeral 13 denotes RDS data, received electric field strength Lb,
It is a controller of a microcomputer configuration that performs automatic follow-up processing and the like based on the station detect signal SD and the like. still,
13a is an internal memory of the controller 13
In the automatic tracking operation based on the list, the frequency (frequency history data) of the broadcast station that is properly received is recorded in association with the PI code. Broadcasting station name code (PS code)
By recording in correspondence with the PI code, the broadcasting station name can be displayed even when the automatic tracking operation is performed based on the reception frequency history data.

Reference numeral 14 is an operating unit, and 15 is a voltage signal corresponding to the reception frequency data FDT input from the controller. The voltage signal is input to the front end 2 to tune to a predetermined broadcasting station.
It is an LL circuit. In addition, 14a is a memory mode key for turning on / off a mode (reception frequency memory mode) for recording the frequency of a broadcast station that has been legally received during automatic tracking operation, and 14b is an automatic tracking operation based on the reception frequency history data described above. Memory AF to specify whether to perform
It is a search key.

The automatic tracking operation processing of the RDS radio receiver of FIG. 1 will be described below with reference to the flowcharts of FIGS. 2, 3 and 4. (A) Normal automatic follow-up operation When the reception frequency memory key 14a is OFF and the memory AF search key 14b is also OFF, both steps 201 and 202 are NO, and the normal AF list automatic operation is performed according to the flow chart of FIG. Follow-up operation is performed (step 203). The normal AF search operation will be described below with reference to the flowchart of FIG.

The received and demodulated audio signal is input to the speaker 7 via the mute circuit 5 and the amplifier 6 and output as audio. In such a state, the controller 13
Receives the RDS data superposed on the FM broadcast of the current receiving station and sent via the bandpass filter 9, the RDS decoder / clock recovery circuit 9, and the group synchronization / error detection / error correction circuit 10 (step 301).
Further, the controller 13 monitors whether the received electric field strength is below a set level based on the output of the signal meter 11 (step 302).

When the reception condition deteriorates and the controller 13 falls below the set level, the controller 13 includes A in the RDS data.
The frequency of the i-th AF station (the initial value of i is 1) is calculated from the F list, and an A of 10 msec is applied to the i-th AF station.
Execute F station search processing. That is, the mute command M
The UT is output to the mute circuit 5 to mute the sound, the PLL circuit 15 is instructed to receive the i-th AF station, and the front end 2 is tuned to the frequency of the AF station (step 303).

In the state where the i-th AF station is tuned, it is checked whether the output signal SD of the station detector 12 is at a high level (step 304). If it is at a high level, there is a receiving station. The received electric field strength output is taken in, and the received electric field strengths of the AF stations taken so far are sorted in descending order (steps 305 and 306). After that, or when the signal SD is at the low level in step 304, it is checked whether the AF search is completed for all the AF stations in the AF list (step 307). If not, i + 1 →
i is incremented by i (step 308), the mute is released, the receiving station is returned to the original receiving station, and the i-th A
The search for station F is completed (step 309).

After that, the search cycle of the AF station (for example, 2.
It is checked whether or not 5 seconds have passed (step 310), and if it has passed, the processing from step 303 onward is repeated. Then, when the AF search processing is completed for all the AF stations, the reception electric field strength level La of the current reception station is compared with the maximum reception electric field strength level Lm of the AF station (step 311), and La ≧
If it is Lm, it is not necessary to change the receiving station, so step 3
The processing returns to 01 and the subsequent processing is repeated.

However, if La <Lm, the controller 13 indicates to the PLL circuit 15 the maximum received electric field strength A.
The reception of the F station is commanded, and the front end 2 is tuned to the broadcasting frequency of the AF station (step 312). Next, the PI code included in the RDS data sent superimposed on the FM signal is extracted, and it is checked whether the PI code matches the PI code indicating the broadcast program name broadcast by the original receiving station ( (Step 313) If they match, the AF station having the maximum received electric field strength is set as the receiving station, and the process returns to step 301 to repeat the subsequent processing. In the reception frequency memory mode, the frequencies of this AF station are stored in sequence,
It becomes the reception frequency history data.

If the PI codes do not match, the received frequency is returned to the original broadcast frequency of the receiving station (step 314),
Then, delete it from the AF list (step 315),
Next, the AF station having the largest received electric field strength is set as the AF station having the maximum received electric field strength (step 316), and the processing from step 311 is repeated. (B) Memory AF search In a region where automatic follow-up operation by a normal AF list is difficult, such as when a network of the current receiving station is adjacent to a broadcasting station of another network, the history of the receiving frequency is stored, and Follow good broadcast stations according to history.

Storage of Received Frequency History Data First, the memory mode key 14a is pressed to turn on the received frequency memory mode. As a result, "YES" is determined in the step 201, and a normal AF search routine (Fig. 3) is executed until the memory mode is released (step 204). The AF search routine is executed when the received electric field strength becomes equal to or lower than the set level, and when the same PI is determined in step 313, the maximum broadcasting frequency of the AF station is stored (step 205). Thereafter, similar processing is performed, and history data of the reception frequency of the section in the reception frequency memory mode is sequentially created in the memory 13a. Note that FIG. 1 shows the reception frequency history data FC1 in the section, and the frequencies are held in the order of reception in correspondence with the PI / PS data.

Memory AF search operation When the following operation according to the stored reception frequency history data is performed, the memory mode key 14a is turned off and the memory AF search key 14b is turned on at the starting point of the section.
N From this, since "NO" in step 201 and "YES" in step 202, the controller 13 checks whether the reception frequency history data exists (step 206), and if not, executes a normal AF search routine. (Step 203). However, if the reception frequency history data exists, the automatic tracking operation according to the memory AF search routine (FIG. 4) is executed (step 2).
07). In the memory AF search routine, it is monitored by the output signal of the signal meter 11 whether or not the received electric field strength is below the set level (step 401), and when it falls below, the controller 13 determines the jth position from the internal received frequency history data. The frequency data of (the initial value of j is 1) is obtained (step 402), the PLL circuit 15 is instructed to receive, and the front end 2 is tuned to the station of the frequency (step 403). Next, j is incremented by j + 1 → j (step 404) and the process returns to step 401.

In the above, the frequency history data is stored in only one section, but it is also possible to store the frequency history data in two or more sections.

[0023]

As described above, according to the present invention, AF is performed in a certain section.
Performs automatic tracking according to the list, leaves the frequency received in that section as received frequency history data, and when moving in the same section, the automatic tracking operation is executed based on the data, so broadcasting on different networks Even in an area where stations are adjacent to each other, good reception can be performed without following a broadcasting station on a different network.
Also, while performing the reception that relies on this automatic tracking operation,
It is possible to eliminate the feeling of sound interruption and noise due to mute during AF search, which is seen in the conventional automatic tracking operation.

[Brief description of drawings]

FIG. 1 is a block diagram of an RDS radio receiver according to the present invention.

FIG. 2 is a flowchart of automatic tracking processing according to the present invention.

FIG. 3 is a flowchart of a normal automatic tracking process using an AF list.

FIG. 4 is a flow chart of automatic tracking processing by AF memory search according to the present invention.

FIG. 5 is a diagram illustrating a problem of a conventional automatic tracking operation.

[Explanation of symbols]

 13 ... Controller 13a ... Internal memory 14 ... Operation part 14a ... Memory mode key 14b ... Memory AF search key

Claims (1)

[Claims] 1. An RDS radio receiver that automatically tunes to a frequency of the same program broadcasting station having a good reception state and performs automatic tracking based on a frequency list of the same program broadcasting station transmitted superimposed on an FM broadcast signal. In the automatic tracking method, automatic tracking is performed based on a certain section and frequency list, the frequency received in that section is recorded as received frequency history data, and when moving in the same section, it is based on the received frequency history data. An automatic tracking method for an RDS radio receiver, which is characterized by performing an automatic tracking operation.