JPH088467B2 - Radio receiver automatic tuning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an automatic channel selection method for a radio receiver, and in particular to RD.
Reception of data-multiplexed radio broadcasting such as S receiver and LOCAL / DX
The present invention relates to an automatic channel selection method for a radio receiver capable of switching the input sensitivity.

<Prior Art> In Europe, RDS (Radio Data System) has been put into practical use for the purpose of facilitating the acquisition of traffic information by car radio and enhancing the tuning function. This RDS
Is for superimposing various digital data on FM radio broadcasting, and the currently received FM is used as a message.
Broadcast (i) Program identification code (PI code) (ii) Broadcast station name (PS) (iii) Broadcasting station frequency list (AF) during the same program (iv) Program content identification code (PTY) (v) Transmission Status identification code (DI) (vi) Music or conversation identification code (M / S), (vii) Traffic information broadcasting station identification code (TP) (viii) Traffic information broadcasting identification code (TA), etc. There is.

As described above, in RDS, various kinds of messages relating to the FM broadcast being received are multiplexed, so that it is possible to perform a special automatic tuning operation that has never been done by using the message.

As an example, in addition to the normal seek, RDS receiver seeks are skipped by stations that are not RDS stations and tuned only to RDS stations.
RDS seek is prepared.

FIG. 6 is a flow chart of such conventional RDS seek control. When the RDS seek command is issued by pressing the RDS seek key, the tuning frequency is increased by a predetermined frequency step Δf after muting the audio output (steps 101, 10).
2) Referring to the station detector output, it is checked whether or not there is a receiving station (step 103). If there is no receiving station, the tuning frequency is further changed by Δf and the above processing is repeated. If there is a receiving station, it is judged whether the receiving station is an RDS station by referring to the RDS decoder output (step 104), and RD
If it is the S station, the mute is turned off to end the seek (step 105). If it is not the RDS station, the process returns to step 102 to change the tuning frequency by .DELTA.f again and the subsequent processing is repeated.

<Problems to be solved by the invention> By the way, since there are many RDS stations in Europe,
When trying to search for a desired station by RDS seek in the entire reception band, it may be necessary to repeat pressing the RDS seek key dozens of times.

Therefore, it is possible to switch the input sensitivity of LOCAL / DY
In the case of an S receiver, you can press the RDS seek key with the input sensitivity set to LOCAL mode in advance so that you can perform RDS seek by narrowing down to only the station with a good reception condition from the many receivable RDS stations. is there.

At this time, the threshold for the presence of a receiving station in the station detector is relatively increased by the amount of decrease in the input sensitivity, and the detectable FM stations are limited to stations with a received electric field strength above a certain level. Even if the seek is repeated over the entire band, a large number of stations are not detected.

However, since the RDS decoder demodulates digital data, correct demodulation operation cannot be performed unless the input level of the station detector is much higher than the input level that can be detected by the station.

Therefore, in the LOCAL mode, data is not output from the RDS decoder unless the received electric field strength is quite strong.
Therefore, there was a problem that the station was not considered as an RDS station even though it was detected by the station detector, and the RDS station that should be caught should be missed. This is the same when performing other automatic tuning such as auto memory and scanning for RDS stations under LOCAL mode.

From the above, it is an object of the present invention to provide an automatic tuning method for a radio receiver that does not miss a data-multiplexed radio broadcasting station that should originally be caught even if the automatic tuning is performed in the LOCAL mode.

<Means for Solving the Problems> In the present invention, the above-mentioned problems are according to the automatic channel selection command,
In the LOCAL mode, the reception frequency varying means for varying the reception frequency until the receiving station is detected, and the input sensitivity switching means for temporarily switching to the DX mode when the receiving station is detected,
This is achieved by the RDS station discriminating means for discriminating whether or not the receiving station is the RDS station after switching to the DX mode, and the means for performing a predetermined operation according to the type of the automatic channel selection command based on the discrimination result.

<Operation> In accordance with the automatic tuning command, the receiving station is detected while varying the receiving frequency in LOCAL mode, and when the receiving station is detected, it is temporarily switched to DX mode and it is determined whether it is a data multiplex radio broadcasting station. Then, based on the determination result, a predetermined operation according to the type of the automatic channel selection command is performed.

As described above, according to the present invention, after detecting the receiving station in the LOCAL mode, switching to the DX mode and determining whether the detected receiving station is the data multiplex radio broadcasting station is performed. An input level sufficient for demodulation can be obtained, and the data-multiplexed radio broadcasting station which should be caught should not be missed.

<Embodiment> FIG. 1 is an RDS for realizing an automatic channel selection method according to the present invention.
It is a principal part block diagram of a radio receiver.

Reference numeral 1 is an antenna, and 2 is a LOCAL / DX switching circuit, which switches the input sensitivity between the LOCAL mode (attenuator on) and the DX mode (attenuator off) based on a switching signal SC input from a controller 12 described later. Reference numeral 3 denotes a front end, which tunes to a predetermined broadcasting station on the basis of a voltage signal input from a PLL circuit 14 described later to generate an intermediate frequency signal. An intermediate frequency amplification / FM detection circuit (IF / DET) 4 amplifies the intermediate frequency signal converted by the front end 3 and also performs FM detection. A stereo demodulation circuit (MPX) 5 demodulates to an FM detection signal stereo signal input from the intermediate frequency amplification / FM detection circuit 4. 6 is a mute circuit, 7 is an amplifier (AMP), and 8 is a speaker, which is driven by the amplifier 7 and outputs sound.

9 is an RDS decoder, which is an intermediate frequency amplification / FM detection circuit 4
The digital data superimposed on the FM detection signal output from is demodulated. A signal meter 10 detects the reception level (reception field strength) of the reception station by monitoring the signal strength of the intermediate frequency signal output from the intermediate frequency amplification / FM detection circuit 4. Reference numeral 11 is a station detector, which determines that a receiving station exists (there is an FM station) when the received signal is within the frequency deviation Δf (bandwidth) of the received signal and the signal strength is equal to or more than a set threshold value. is there.

12 is a controller of a microcomputer configuration that performs automatic tracking processing and RDS automatic channel selection processing based on RDS data, received electric field strength signal SM, station detect signal SD, etc., 13 is an operation unit, 14 is a reception frequency input from the controller 12. It is a PLL circuit that inputs a voltage signal corresponding to the data FDT to the front end 3 and tunes it to a predetermined broadcasting station.

In addition, 13a is an input sensitivity switching key, 13b is an RDS seek key for executing an RDS seek, 13c is an RDS auto memory key for executing an RDS auto memory, 13d is an RDS scan key for executing an RDS scan, and 13e is an RDS scan. The stop key 13f is a preset channel key for channels 1 to 9.

The controller 12 also performs input sensitivity switching processing and preset reception processing.

The RD of FIG. 1 will be described below according to the flowcharts of FIGS. 2 to 5.
The RDS automatic channel selection processing of the S radio receiver will be described.

First, the sensitivity switching process and the RDS seek process will be described with reference to FIGS. 2 and 3.

It is assumed that the LOCAL / DX switching circuit 2 is set to the DX mode (A = 0) by the input sensitivity switching key 13a in advance.
Incidentally, A indicates a sensitivity state (DX / LOCAL) selected by the input sensitivity switching key 13a.

When the input sensitivity switching key 13a is pressed to perform RDS seek only for RDS stations with good reception, the controller 12 outputs the switching signal SC to the LOCAL / DX switching circuit 2.
The LOCAL mode (A = 1) is set (steps 201 to 203).

Subsequently, when the RDS seek key 13b is pressed and the RDS seek command is issued, the controller 12 controls the mute circuit 6 to mute on to mute the audio output (step 301) and the reception frequency changed by one step. The data FDT is input to the PLL circuit 14 to increase the tuning frequency by Δf (step 302).

The controller 12 then moves to the station detector 11
It is checked whether or not there is an FM receiving station by referring to the output of (step 303).

If there is no receiving station, the above process is repeated while increasing the tuning frequency in increments of Δf. When there is a receiving station, since the input sensitivity switching key 13a is in LOCAL mode in this case, the controller 12 sends the switching signal SC to LOCAL / DX. Output to the switching circuit 2 and temporarily set to DX mode (steps 304 and 305), RD
The input level of the S decoder 9 is increased to a level sufficient for data demodulation.

Next, the controller 12 determines whether or not the detected receiving station is the RDS station, depending on whether or not the data is input from the RDS decoder 9 (step 306).

If it is an RDS station, the controller 12 sends the switching signal SC to LOCAL / D
Output to the X switching circuit 2 and return to the LOCAL mode selected by the input sensitivity switching key 13a (steps 307, 30).
8) Then, mute off control is performed on the mute circuit 6 to turn off the mute and finish the seek (step 30).
9).

If it is not an RDS station, in other words, if RDS data cannot be demodulated, after returning to the LOCAL mode selected by the input sensitivity switching key 13a (steps 310 and 311), step 302
Then, the tuning frequency is increased by Δf and the seek operation is continued.

After that, if it is an RDS station when the receiving station is detected, the seek is ended.

If the RDS seek key 13b is pressed while the input sensitivity switching key 13a is in DX mode, switching to DX mode or LOC
No return processing to AL mode is performed (steps 304, 30
7, 310 NO judgment).

Next, the RDS auto memory process will be described with reference to FIG.

For example, when the RDS auto memory key 13c is pressed and the RDS auto memory command is generated in the state where the DX mode is set in advance by the input sensitivity switching key 13a (A = 0), the controller 12 mutes the audio output. Hanging (step 40
1), i corresponding to the preset channel number is set to 1 (step 402), and at first, only the RDS station with a good reception state is targeted and auto memory is switched to the LOCAL mode (steps 403 and 404).

Next, the reception frequency data changed by one step
The FDT is input to the PLL circuit 14 to increase the tuning frequency by Δf (step 405), and the output of the station detector 11 is referred to check whether or not there is an FM receiving station (step 406).

If there is no receiving station, the above process is repeated while increasing the tuning frequency in units of Δf, and when there is a receiving station, the controller 12 outputs the switching signal SC to the LOCAL / DX switching circuit 2 to temporarily set the DX mode. (Step 407), an input level sufficient for demodulating data is set.

Next, the controller 12 determines whether the detected receiving station is an RDS station (step 408).

In the case of an RDS station, the received electric field strength signal SM output from the signal meter 10 is input (step 409), and i> 9 is not satisfied (NO in step 410). Therefore, the frequency data F and SM of the receiving station are input to one channel. The frequency data F ₁ and the received electric field strength data SM ₁ are stored in the channel memory (steps 410 and 411).

Then i is incremented to 2 (step 41
2) Judge whether the reception frequency band has passed once (step 4
13) If it has not completed one cycle, return to step 404 to return to the LOCAL mode, increase the tuning frequency by Δf, and repeat the same processing.

If it is determined in step 408 that the station is not the RDS station, the process returns to step 404.

Repeat the same process while scanning the frequency, and after a total of 9 RDS stations have been stored in memory (F _{1 to} F ₉ and SM ₁ to SM ₉
If a new RDS station is caught before the reception frequency band is cycled, the controller 12 determines YES in step 410 and determines the minimum value SM _L among SM ₁ to SM ₉
And SM are compared (step 414) and when SM is larger F
_L = F, rewritten as SM _L = SM (step 415), always to ensure large reception field strength remains.

RD for 9 channels if the reception frequency band is complete
It is judged whether the S station is caught (step 416), and if it is caught, the frequency data in the channel memory memory
Rearrange F _{1 to} F ₉ in descending order of received field strength (step
417), since it is the DX mode in advance, the mute is turned off and the RDS auto memory is ended (steps 418, 420).

RDS for 9 channels when the reception frequency goes round
If the station catch is not complete, the controller 12 now increases the tuning frequency by Δf under DX mode (step
421), referring to the output of station detector 11 FM
It is checked whether there is a receiving station of (step 422).

If there is no receiving station, the above processing is repeated while increasing the tuning frequency in units of Δf, and when there is a receiving station, the controller 12 determines whether the receiving station detected under DX mode is the RDS station (step 423).

In the case of an RDS station, the received electric field strength signal SM output from the signal meter 10 is input (step 424), and i> 9 is not satisfied (NO in step 410). Therefore, the frequency data F and SM of the receiving station are input to the i channel. The frequency data F _i and the received electric field strength data SM _i are stored in the channel memory (steps 425 and 426).

Next, i is incremented (step 427) and it is judged whether or not the reception frequency band has completed one cycle (step 428). If it has not completed one cycle, the process returns to step 421 to set the tuning frequency to Δ.
f is increased and the same processing is repeated.

If it is determined in step 423 that the station is not the RDS station, the process returns to step 421.

When a new RDS station is caught before the second round of the reception frequency band is completed after a total of nine RDS stations have been stored in memory by repeating the same process while searching for frequencies, the received electric field strength is If it is larger than the minimum value of the received electric field strength of the stored station, the frequency data is rewritten (steps 429, 430).

After that, once the reception frequency band has been circulated, the frequency data in the memory is rearranged in the descending order of the received electric field strength (step 417). Since it is in DX mode in advance, mute is turned off and RDS is turned on.
The auto memory is terminated (steps 418 and 420).

In the RDS auto memory, the RDS station is searched for in the LOCAL mode at first regardless of whether LOCAL / DX is set in advance. However, when the LOCAL mode is set in advance, RDS
Before ending the auto memory, the mode is returned to the LOCAL mode (steps 418 and 419).

Next, the RDS scan process will be described with reference to FIG.

For example, when the RDS scan key 13d is pressed to generate an RDS scan command in a state where the input sensitivity switching key 13a is set to the LOCAL mode (A = 1) in advance, the controller 12 mutes the audio output ( Step 50
1).

Then, the tuning frequency is increased by Δf (step 50
2) Referring to the output of the station detector 11, it is checked whether or not there is an FM receiving station (step 503).

If there is no receiving station, the above process is repeated while increasing the tuning frequency in units of Δf, and when there is a receiving station, the controller 12 temporarily sets the DX mode (steps 504 and 505).

Then, it is determined whether the receiving station is an RDS station (step 506).

If it is not an RDS station, return to LOCAL mode (steps 507, 5
08), returning to step 502, the tuning frequency is further increased by Δf.

If it is an RDS station, unmute it once (step 50
9) Wait until the stop key 13e is pressed within a fixed time (steps 510 and 511).

When the stop key 13e is pressed before the elapse of a certain time, the controller 12 determines YES in step 510, and the LOCA
Return to L mode and end RDS scan (step 51).
2, 513).

When the stop key 13e is not pressed for a certain period of time, the controller 12 determines YES in step 511, and the LOCA
Returning to the L mode (steps 507 and 508), returning to step 502, the tuning frequency is further increased by Δf, and the same processing is repeated.

If the RDS scan key 13e is pressed in the DX mode, neither switching to the DX mode nor returning to the LOCAL mode is performed (NO in steps 504, 507 and 512).

<Advantages of the Invention> As described above, according to the present invention, the receiving station is detected while varying the receiving frequency in the LOCAL mode according to the automatic tuning command, and when the receiving station is detected, the DX mode is temporarily switched to the data multiplexing. Since it is configured to determine whether it is a radio broadcasting station and perform a predetermined operation according to the type of automatic tuning command based on the determination result, demodulation of digital data even if automatic tuning is performed in LOCAL mode A sufficient input level can be obtained for the data multiplex radio broadcasting station which should be caught.

[Brief description of drawings]

FIG. 1 is a block diagram of an RDS radio receiver that executes automatic channel selection processing according to the present invention, FIG. 2 is a flow chart of the input sensitivity switching processing of FIG. 1, and FIG. 3 is the RDS seek processing of FIG. A flow chart, FIG. 4 is a flow chart of the RDS auto memory processing of FIG. 1, FIG. 5 is a flow chart of the RDS scan processing of FIG. 1, and FIG. 6 is a flow chart of the conventional RDS seek processing. 2 …… LOCAL / DX switching circuit 9 …… RDS decoder 10 …… Signal meter 11 …… Station detector 12 …… Controller 13a …… Input sensitivity switching key 13b …… RDS seek key 13c …… RDS Auto memory key 13d …… RDS Scan key

Claims (1)

[Claims] 1. A radio receiver capable of receiving a data-multiplexed radio broadcast and switching input sensitivity is set to LOCAL mode, and a receiving station is detected and detected while varying the receiving frequency according to an automatic tuning command. It is determined whether or not the receiving station is a data-multiplexed radio broadcasting station, and based on the result of the determination, a predetermined operation is performed according to the type of automatic tuning command. The detection of the receiving station while changing the is performed in the LOCAL mode.When the receiving station is detected, the mode is temporarily switched to DX mode to determine whether the detected receiving station is a data multiplex radio broadcasting station. What to do is an automatic tuning method for radio receivers.