JPH03188716A - Automatic tracking method for radio receiver - Google Patents

Abstract

PURPOSE:To seek an FM broadcast of the same language as a language of the FM broadcast having been received so far and to select the channel by seeking an RDS station whose reception electric field strength is a setting level or over, and receiving the station consecutively when the country identification code included in an RDS data is coincident with the counter identification code of a reception station received so far. CONSTITUTION:When the received electric field strength La of a current reception station is a setting level Ls or below, a controller 14 changes a tuning frequency at the interval of a prescribed frequency to seek stations whose reception electric field strength is the setting level Ls or over. When a station whose strength is the setting level Ls or over is found out, the controller 14 references a signal SDT to check whether or not a seek station is the RDS station, a PI code is extracted from the FM broadcast signal of the seek station, and whether or not a 'counter identification code' included in the PI code is coincident with the counter identification code of the PI code of the original reception station stored in a built-in memory 14a, the seeking is finished when they are coincident to receive the FM broadcast from the said seek station.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an automatic tracking method for a radio receiver, and in particular to an R method for preventing switching to a broadcasting station in a different language near a border.
This invention relates to an automatic tracking method using DS data.

<Prior Art> In addition to being able to easily obtain traffic information, car radios are required to have sophisticated tuning functions. In particular, this demand is strong in Europe, where FM broadcasting with a relatively narrow service area is the main radio broadcasting service, and where a high proportion of car radios receive broadcasts. system) has been proposed and is being put into practical use. This RD
S is a method that superimposes various digital data on the FM radio broadcast signal, and the message is (i) program identification code (PI code) (n) broadcasting station name (ps) of the currently received FM broadcast ( iii) Broadcasting station frequency list (AF
) (iv) Program content identification code (PTY) (v) Transmission status identification code (DI) (vi) Music or conversation identification code (M/S code) and (F) Traffic information broadcasting station identification code ( vii) There is an identification code etc. during traffic information broadcast. still,
The PI code is composed of 16 bits including a program code and a country identification code, and is transmitted at a frequency of 11 times/second. Further, (i) to (vi) above are information related to the channel selection function, and (vii) to (width) are traffic information.

In this way, with RDS, messages related to the FM broadcasts being received are transmitted multiplexed, so that unprecedented channel selection operations can be performed using these messages.

For example, the frequency data (AF list) of the same program broadcasting station is demodulated at predetermined intervals, and the received field strength is checked by sequentially tuning to each AF station on the AF list. It is possible to tune to the frequency of the station (automatic tracking). In such automatic tracking processing, the received field strength of each AF station is checked by tuning the 10 m5ec front end to the AF station frequency and muting it during the time, Since the mute time is short, you can listen to the broadcast from the original receiving station without feeling uncomfortable.

<Problems to be Solved by the Invention> In the automatic tracking system using such RDS data, when a car enters a mountainous area and is affected by the topography, the received electric field strength of any of the same program broadcasting stations may be lower than that of the current receiving station. When the field strength is below the set level or below the set level, and the received field strength of the current receiving station is below the set level, it seeks an RDS station whose received field strength is above the set level, and receives the FM broadcast signal from the sought station. I try to do that.

However, in the conventional method, which simply switches to the RDS station (seek station) whose received electrolytic strength is higher than the set level, the conventional FM
There may be cases where the broadcast language and the seek station's broadcast language are different,
Gives a sense of discomfort to the user. For example, if a car is driving near the border between Germany and France and is receiving a German broadcast, there is a problem in that the seek operation switches to the French broadcast.

An object of the present invention is to provide an automatic tracking method for a radio receiver that can seek and switch to an FM broadcast in the same language as the FM broadcast it has been receiving in an automatic tracking method using RDS data. That's true.

Means for Solving the Problems> The above problems can be solved in the present invention by an automatic tracking means using an AF list included in RDS data, a means for seeking an RDS station whose received field strength is equal to or higher than a set level, and a country identification method. This is achieved by code identity determining means.

Effect> In the automatic tracking method using RDS data, the received electric field strength of any of the same program broadcasting stations is less than the received electric field strength of the current receiving station, or less than the set level, and the received electric field strength of the current receiving station is less than the set level. If the received field strength is below the set level, seek the RDS station whose received field strength is above the set level, and
It is checked whether the country identification code included in the RDS data of the DS station matches the country identification code of the previous receiving station, and if they match, the FM broadcast from the sought RDS station is continuously received.

<Embodiment> FIG. 1 is a block diagram of the main parts of a radio receiver that implements the automatic tracking method according to the present invention.

1 is an antenna, 2 is a front end, and P
Based on the voltage signal output from the LL circuit, an intermediate frequency signal is generated in tune with a predetermined broadcasting station. 3 is an intermediate frequency amplifier, which amplifies the intermediate frequency signal converted by the front end 2.

A stereo demodulation circuit (MPX) 4 demodulates the intermediate frequency signal input from the intermediate frequency amplifier 3 into a stereo signal. 5 is a mute circuit, 6 is an amplifier (AMP), 7
is a speaker, which is driven by the amplifier 6 and outputs audio.

8 is a 57 KHz bandpass filter (BPF), which is a 57KH bandpass filter (BPF) that is amplitude modulated based on RDS data.
Pass the subcarrier of z. Reference numeral 9 denotes an RDS decoder, which demodulates the AF list, PI code, etc. from the output of the bandpass filter. Reference numeral 10 denotes an error correction circuit, which detects errors in RDS data such as the AF list and PI code demodulated by the RDS decoder 9 while synchronizing each group, and corrects the errors.

11 is based on the output signal of the bandpass filter 8 (5
This is an RDS station detection circuit that outputs a signal SDT indicating whether the current receiving station is an RDS station (based on the presence or absence of a 7KHz component). If it is an RDS station, the signal SDT is set to high level, and if it is not an RDS station, it is set to low level. Make it.

Reference numeral 12 denotes a signal meter, which detects the reception level (reception electric field strength) of the receiving station by monitoring the signal strength of the intermediate frequency signal output from the intermediate frequency amplifier 3. 1
3 is a station detector, which determines that a receiving station exists when it is within the range of the frequency deviation Δf (bandwidth) of the received signal and the signal strength is equal to or higher than the set level Ls; for example, a station detector made by Toshiba Integrated circuit TA91210Z
It has been commercialized as. Therefore, when the station detect signal SD is low level, the signal meter 1
Even if the signal strength detected by No. 2 is large, it is determined that the broadcasting station at the tuning point does not actually exist and that the detected signal strength is influenced by an adjacent station.

14 is a microcomputer-configured controller that performs automatic tracking processing (to be described later) and digital tuning processing based on RDS data, received electric field strength, station detect signal SD, RDS station detection signal SDT, etc.; 15 is an operation unit; and 16 is a microcomputer configured controller that performs digital tuning processing. This is a PLL circuit that inputs a voltage signal corresponding to reception frequency data FDT input from the controller to the front end 2 and tunes it to a predetermined broadcast station.

The automatic tracking process of the radio receiver shown in FIG. 1 will be explained below according to the flowchart shown in FIG.

The controller 14 receives a predetermined RDS from the radio receiver.
While the broadcast program from the station is being received, the following automatic tracking process is performed at predetermined time intervals.

RD that is being sent superimposed on the FM broadcast of the current receiving station
S data (AF list, P echo, etc.) is received via the band pass filter 8, RDS decoder 9, and error correction circuit 10, and is stored in the built-in memory 14a (step 101).

After that, the i-th AF list included in the RDS data is selected.
Find the AF station frequency of the i-th (initial value of i is 1),
A lomsec AF station search process is executed for the th AF station. That is, the mute command MUT is output to mute the audio, and the PLL circuit 16 is commanded to receive the i-th AF station, and the front end 2 is tuned to the frequency of the AF station (step 102).

Thereafter, it is checked whether the station detect signal SD is at a high level (step 103).

If the level is high, there is a station, so next, the received electric field strength Lb is taken in from the signal meter 12.

The received field strength Lb is compared with the received field strength level La of the previous receiving station (current receiving station) (step 104).
.

If La<Lb, the controller 14 uses the PLL circuit 1
6 to receive the i-th AF station, and the front end 2 is tuned to the broadcast frequency of the AF station (step 1).
05), the process returns to step 101 and repeats the same process.

On the other hand, if the station detector signal SD is at a low level in step 103, or the received electric field strength Lb of the AF station is the received electric field strength La of the previous receiving station.
If it is smaller, muting is canceled and tuning is returned to the original receiving station (step 106).

Thereafter, it is checked whether the AF search has been completed for all AF stations in the AF list (step 107), and if it has not been completed, i is incremented by i+1→i and the processing from step 102 onward is repeated (step 108).

However, if AF chaining has been completed for all AF stations on the AF list, in other words, the received electric field strength of any of the same program broadcasting stations on the AF list will be less than or equal to the received electric field strength La of the previous receiving station. Alternatively, if it is below the set level Ls, check whether the received field strength La is below the set level Ls (step 108); if La2Ls, return to step 101 while tuning to the previous receiving station and perform the subsequent processing. repeat.

If the received field strength La of the current receiving station is less than the set level Ls, the controller 14 changes the tuning frequency in predetermined frequency increments and seeks a station whose received field strength is equal to or higher than the set level Ls (step 109).

If a station having a level equal to or higher than the set level Ls (seek station) is found by the seek, the controller 14 refers to the signal SDT to check whether the seek station is an RDS station or not (step 110).
), if it is not an RDS station, the seek in step 109 is continued.

If the seek station is an RDS station, the PI code is extracted from the FM broadcast signal of the seek station, and the "
Check whether the "country identification code" matches the country identification code of the PI code of the original receiving station stored in the built-in memory 14a (step 111); if it does not match, continue the seek in step 109 and find a match. If so, the seek is finished, the FM broadcast from the seek station is received, and thereafter the process returns to step 101 and the same process is performed.

<Effects of the Invention> According to the present invention, the received electric field strength of any of the same program broadcasting stations in the AF list is equal to or lower than the received electric field strength of the current receiving station, or lower than the set level, and the received electric field strength of the current receiving station is is below the set level, the RDS station whose received field strength is above the set level is sought, and the sought R
When the "country identification code" included in the RDS data of the DS station matches the "country identification code" of the previous receiving station, the FM broadcast signal from the sought RDS station is received, and if it does not match, it is not received. With this configuration, there is no possibility of switching to a station with a different language in the RDS automatic tracking system.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a radio receiver that executes automatic tracking processing according to the present invention. FIG. 2 is a flowchart of the automatic tracking process of the present invention. 2..FM front end 9..RDS decoder 11..RDS station detection circuit 12..Signal meter 13..Station detector 14..Controller 16..PLL circuit

Claims (1)

[Claims] The RDS data sent superimposed on the FM broadcast signal is demodulated, the received field strength of the same program broadcasting station is determined based on the AF list included in the RDS data, and the received field strength is calculated based on the AF list included in the RDS data. In the automatic tracking method of a radio receiver that selects a large same program broadcasting station, the received field strength of any same program broadcasting station is less than the received field strength of the current receiving station, or is less than the set level, and the current receiving station's reception is If the electric field strength is below the set level,
Seek the RDS station whose received field strength is higher than the set level,
It is checked whether the country identification code included in the RDS data of the sought RDS station matches the country identification code of the current receiving station, and if they match, the F from the sought RDS station is
An automatic tracking method for a radio receiver, characterized in that it receives an M broadcast signal.