JPH03148923A - Automatic follow-up method for radio receiver - Google Patents

Abstract

PURPOSE:To eliminate a sense of incompatibility and the deterioration of tone quality owing to muting in an automatic follow-up processing by deciding time intervals for checking the strength of the reception electric field of an AF station in accordance with the speed of a vehicle and checking the strength of the reception electric field of the AF station after the time interval concerned elapses. CONSTITUTION:The corresponding table of the speed of the vehicle S and the time interval T for checking the strength of the reception electric field of the AF station is previously stored in a memory 14a incorporated in a controller 14. Then, the time interval of the automatic follow-up processing is set to be longer as the speed of the vehicle becomes lower. The present travel speed S is identified by using the detection signal of a vehicle speed sensor 13, the time interval T of the automatic follow-up processing, which correspond to the travel speed S concerned, is obtained from the corresponding table. When the time interval T of AF search elaspes, an i-numbered AF station frequency is obtained from an AF list included in RDS data and the AF station searching processing of 10msec is executed as against an i-numbered AF station concerned.

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, a method for tuning to a same program broadcasting station with a large received field strength based on frequency data of the same program broadcasting station. Regarding automatic tracking method.

<Prior Art> It would be convenient if traffic information in each area could be easily obtained using a car radio. For this reason, the ARI broadcasting system has been adopted in countries such as West Germany, Austria, and Switzerland, which not only broadcasts traffic information at appropriate times but also includes identification data and traffic information indicating that the current receiving station is a traffic information broadcasting station in the FM broadcast signal. Identification data indicating that the broadcast is being broadcast is superimposed, and this data can be used to easily listen to traffic information.

By the way, when a car travels a long distance and leaves the service area of a receiving station, it becomes necessary to reselect the station each time. For this reason,
Recently, in addition to being able to easily obtain traffic information, there has been a demand for more sophisticated channel selection 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 RDS is F
It is a method that superimposes various digital data on the M radio broadcast signal, and the message is the FM radio currently being received.
Broadcast (i) Program (broadcast program) identification data (PI) CM
) Broadcasting station name (ps) (in) Broadcasting station frequency list (AF) that is broadcasting the same program
(iv) Program content identification data (PTY) (V) Transmission status identification data (DI) (vi) Music or conversation identification data (M/S data) and (vi) Traffic information broadcasting station identification data (TP data)(
vi) Identification data (TA data) during traffic information broadcasting, etc. Note that (i) to (vi) above are information related to the channel selection function, and (%Ql) to (vi) 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, 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 available AF station (referred to as automatic tracking).The time interval for checking the received field strength of the AF station is 2.5 seconds in the case of IR.

Problems to be Solved by the Invention> Now, in the automatic tracking process, the 1
Check the reception status of each AF station once every 2.5 seconds.
This is done by tuning the front end to the AF station frequency for about 0 m5ec and muting during that time. This allows the user to listen to the broadcast from the original receiving station without feeling uncomfortable.

However, even if you mute the device for a period of time that does not cause discomfort and check the reception status during that time, there is always a phenomenon in which the sound is interrupted intermittently, so there is an undeniable deterioration in the sound quality.
For this reason, it is desirable to make the time interval for checking the received field strength of the AF station as long as possible, but if it is too long, there is a problem that if the field strength of the receiving station becomes weak, the timing of automatic tracking will be delayed.

From the above, it is an object of the present invention to provide an automatic radio receiver that can achieve good reception without delaying the timing of automatic tracking by changing the time interval for checking the received field strength of the AF station according to the vehicle speed. The purpose is to provide a tracking method.

Means for Solving the Problems The present invention solves the above problems by using a vehicle speed detection sensor, a means for determining a time interval for checking the received field strength of an AF station according to the vehicle speed, and an automatic tracking process. This is accomplished by means of

<Operation> The vehicle speed is detected, a time interval for checking the received field strength of the AF station is determined according to the vehicle speed, and the received field strength of the AF station is checked after the time interval has elapsed. As a result, if the car is driving at low speed and the reception status changes slowly,
The time interval for checking the received field strength of station F can be lengthened, and the number of mutes can be reduced. Also, when the car is driving at high speed and the reception status changes rapidly, the time interval for checking the reception field strength of the AF station can be shortened, and even if the reception station's field strength becomes weak, the timing of automatic tracking can be adjusted. Never be late.

<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 (IF) is generated in tune with a predetermined broadcast station. 3 is an intermediate frequency amplifier, which amplifies the intermediate frequency signal converted by the front end 2 to a predetermined level. 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), and 7 is a speaker, which is driven by the amplifier 6 and outputs audio.

8 is a 5 KHz band pass filter (BPF)
and 57K amplitude modulated based on RDS data.
Hz subcarrier is passed. Reference numeral 9 denotes an RDS decoder, which demodulates the AF code, PI code, etc. from the bandpass filter output. 10 is an error correction circuit, RDS
Errors in RDS data such as AF code and PI code demodulated by the decoder 9 are detected while synchronizing each group, and the errors are corrected.

11 is a signal meter, which measures the signal strength (for example, electric field strength) of the intermediate frequency signal output from the intermediate frequency amplifier 3;
The level of the reception status of the receiving station is detected by monitoring. 12 is a stage J detector, which determines that a receiving station is present when the received signal is within the range of the frequency deviation Δf (bandwidth) and the signal strength is above a predetermined level. Manufactured integrated circuit TA91210
It is commercialized as Z. Therefore, when the station detect signal SD is at low level.

Even if the signal strength detected by the signal meter 11 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.

13 is a vehicle speed sensor that detects the speed of the car, 14 is RD
A microcomputer-configured controller that performs automatic tracking processing (described later) based on S data, signal meter output, station detector output, vehicle speed, etc., as well as digital tuning processing; 15 is an operation unit; 16 is reception frequency data input from the controller; This is a PLL circuit that inputs a voltage signal according to the FDT to the front end 2 and tunes it to a predetermined broadcast station.

The automatic follow-up process shown in FIG. 1 will be explained below according to the flowchart shown in FIG. Incidentally, a correspondence table of vehicle speed S and time interval T for checking the received electric field strength of the AF station is stored in advance in the memory 14a built in the controller 14, and the third
As shown in the figure, the time interval of automatic tracking processing is made longer as the vehicle speed becomes lower. For example, at 80km/h T
= 2° = 5 seconds, if there is no noticeable deterioration in sound quality due to muting and there is no delay in the timing of automatic tracking, T should be determined in inverse proportion to the speed, such as 5.0 seconds at 40 km.

In a state in which a broadcast program from a predetermined broadcasting station is being received, the current traveling speed S is identified using the detection signal of the vehicle speed sensor 13 (Step 101), and the time interval of automatic tracking processing according to the traveling speed S is determined. (AF distance) T is determined from the correspondence table (step 102).

Next, the RDS data sent superimposed on the FM broadcast of the current receiving station is passed through a bandpass filter 8, an RDS decoder 9. It is received via the error correction circuit 10 (step 103).

After that, check whether the AF search time interval T determined above has elapsed (step 104), and if it has elapsed, the RDS
The i-th (initial value of i is 1) AF station frequency is determined from the AF list included in the data, and a 10+msec AF station search process is executed for the i-th AF station.

That is, a 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 105). , in the tuned state, the output signal SD of the station detector 12
Check whether the level is high (step 106). If the level is high, there is a receiving station, so the signal meter 1
1, and the received field strengths of the AF stations that have been imported so far are sorted in ascending order (steps 107 and 108), or after step 106, when the signal SD is at a low level. teeth,
Check whether the AF search has been completed for all AF stations in the AF list (step 109); if not, check i
Step 110) increments i by +1→i, cancels muting and returns the receiving station to the original receiving station before step 114, and ends the search for the i-th AF station (
Step 111).

Thereafter, the process jumps to step 104, and the processes from step 105 onwards are repeated at a period of time interval T. When the AF search process is completed for all AF stations, the received field strength level La of the current receiving station and the maximum reception of the AF station are determined. Electric field strength level L
(Comparing step 112), if La≧Lm, there is no need to change the receiving station, so the process returns to step 101 and repeats the subsequent processing.

However, if La (Lm), the controller 14
The L circuit 16 is instructed to receive the AF station exhibiting the maximum received field strength, and the front end 2 is tuned to the broadcast frequency of the AF station (step 113).

Next, extract the PI code included in the RDS data sent superimposed on the FM signal, and check whether the PI code matches the PI code indicating the name of the broadcast program that was being broadcast at the original receiving station. 114), if they match,
Returning to step 101, the subsequent processing is repeated.

If they do not match, the receiving frequency is returned to the original broadcasting frequency of the receiving station (step 115) - then the AF station with the highest received field strength is deleted from the AF list (step 116), and the AF station with the highest received field strength is selected as the AF station with the highest received field strength. Step 11
7), repeating the processing from step 112 onwards.

<Effects of the Invention> According to the present invention, the vehicle speed is detected, and the A
Since the time interval for checking the received field strength of the F station is determined, and the received field strength of the AF station is checked after the time interval has elapsed, it is possible to avoid changes in the receiving state when the car is driving at low speed. In this case, the time interval for checking the received electric field strength of the AF station can be lengthened, so the number of times of muting can be reduced, and the discomfort and sound quality deterioration caused by muting in automatic tracking processing can be eliminated. or.

When the car is driving at high speed and the reception status changes rapidly, the interval between automatic tracking processing can be shortened, so even if the electric field strength of the receiving station becomes weak, the timing of automatic tracking will not be delayed. If this happens, the engine noise will become louder, so even if you mute it many times, it will be muted and you will feel uncomfortable.

[Brief explanation of the drawing]

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 automatic tracking processing according to the present invention, and Fig. 3 checks the vehicle speed S and the received electric field strength of the AF station. FIG. 2...FM front end 13...Vehicle speed sensor 14...Controller 16...PLL circuit Patent applicant Alvine Co., Ltd. Agent Patent attorney Chiki Saito Figure 2 (a) (start) l (so check?) -* λ−−1
11 Sort by electric field strength "lIYεS Figure 2 (b) 1!
：”-ko lY
ES conversion 0<Lm) 11
< Same-PI? )Ko! 1 1 Original receiving station [
Return 11 Figure 3 11 ■ S vehicle speed (Km) -

Claims (1)

[Claims] Radio reception in which frequency data of the same program broadcasting station sent superimposed on an FM broadcast signal is demodulated and, based on the frequency data, it is tuned to the frequency of the same program broadcasting station with a large received field strength. In the automatic tracking method, the vehicle speed is detected, a time interval for checking the received field strength of the same program broadcasting station is determined according to the vehicle speed, and the received field strength of the same program broadcasting station is checked after the time interval has elapsed. An automatic tracking method for a radio receiver characterized by performing a check.