JP2561379B2 - RDS radio receiver seek method - Google Patents

Description

The present invention relates to a seek method for an RDS radio receiver, and more particularly to a seek method capable of shortening seek time.

<Prior Art> In addition to being able to easily obtain traffic information, car radios are required to have sophisticated tuning functions. Especially in Europe, where FM broadcasting, which has a relatively small service area, is the main body of radio broadcasting services and the ratio of car radio reception is high, this requirement is strong. Therefore, RDS (Radio Data System) has been proposed and put into practical use by the European Broadcasting Union, which should meet this requirement. This RDS is a method of superimposing various digital data on an FM radio broadcast signal, and as a message, (i) program identification code (PI code) of the currently received FM broadcast (ii) broadcast station name (PS) (Iii) Broadcasting station frequency list (AF) during the same program broadcasting (iv) Program content identification code (PTY) (v) Transmission status identification code (DI) (vi) Music or conversation identification code (M / S code) And (vii) identification code of traffic information broadcasting station (viii) identification code during traffic information broadcasting.

In this way, since the message related to the FM broadcast being received is transmitted in multiple layers in the RDS, it is possible to use the message to perform an exceptionally unprecedented tuning operation. Therefore, the seek of the RDS radio receiver includes, in addition to the usual automatic seek, an RDS seek in which a non-RDS station is skipped and only the RDS station is tuned.

FIG. 3 is a flow chart of such conventional RDS seek control. When the RDS seek key is pressed, the tuning frequency is increased or decreased by a predetermined frequency Δf (step 101), and it is checked whether or not there is a station by referring to the output of the station detector (step 102). If there is no station, Δf is changed and the above process is repeated. If there is a station, wait for a preset time T to elapse (step 103), and if time T elapses, depending on whether RDS data is received, It is determined whether the receiving station is an RDS station (step 104). If it is an RDS station, the seek is ended. If it is not an RDS station, the process returns to step 101 and the tuning frequency is increased or decreased by a predetermined frequency Δf, and the subsequent processing is performed. repeat.

<Problems to be Solved by the Invention> The RDS data demodulated by the RDS decoder becomes a message that can be processed only after the group synchronization is established. However, if the received electric field strength is small, the time required for group synchronization becomes long, and there are cases where synchronization cannot be achieved within the set time T. If the synchronization is not achieved within the set time T in this way, it is not considered as an RDS station even though the receiving station is the RDS station, which is inconvenient.

For this reason, conventionally, the set time T is set to a time long enough to be synchronized even if the received electric field strength is small, for example, 800 mse.
It is set to c.

However, when the received electric field strength is high, synchronization can be achieved within a short time, for example, within about 400 msec. Therefore, when the received electric field strength is large, the conventional set time T
= 800msec was too long, and there was a problem that it took a long time to totally seek the RDS.

From the above, the object of the present invention is to achieve synchronization even when the received electric field strength is low, and to shorten the time required for seek.
It is to provide a seek method in an RDS radio receiver.

<Means for Solving the Problem> In the present invention, the above problem is a seek means, a means for detecting the received electric field strength, and a time for judging whether the receiving station is an RDS station based on the magnitude of the received electric field strength. Is achieved by means of determining the RDS station, determining whether the receiving station is an RDS station, and seeking end / continuation instructing means.

<Operation> During seek, the received electric field strength when tuning to a predetermined broadcasting station is detected, and if the received electric field strength is higher than the set level, the time to judge whether the receiving station is the RDS station is shortened and the set level is set. If it is smaller, the judgment time is lengthened, and after the judgment time has elapsed, it is judged whether the receiving station is an RDS station. If it is an RDS station, seek is ended. If it is not RDS, seek operation is continued.

As described above, according to the present invention, the time for determining whether the receiving station is the RDS station is variable according to the received electric field strength. Therefore, even if the received electric field strength is low, synchronization can be achieved and seek is required. The total time can be shortened.

<Embodiment> FIG. 1 is a block diagram of a main part of a radio receiver for realizing a seek method according to the present invention.

1 is an antenna, 2 is a front end, which will be described later.
An intermediate frequency signal is generated by tuning to a predetermined broadcasting station based on the voltage signal output from the PLL circuit. An intermediate frequency amplifier 3 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. 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 (BPF),
Pass the 57KHz sub-carrier that is amplitude-modulated based on the 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 / 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. 13
Is a station detector, which determines that a receiving station exists (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.

13 is an automatic tracking process based on RDS data, received electric field strength Lb, station detect signal SD, etc.
A controller having a microcomputer configuration for performing seek processing, 14 is an operation unit, and 15 is a PLL circuit for inputting a voltage signal corresponding to the reception frequency data FDT input from the controller to the front end 2 to tune to a predetermined broadcasting station. 14a is RD
RDS seek key to execute S seek.

The RDS seek processing of the radio receiver of FIG. 1 will be described below with reference to the flowchart of FIG.

When the RDS seek key 14a is pressed to request the RDS seek, the controller 13 sets the tuning frequency to the lowest frequency (or highest frequency). That is, the predetermined reception frequency data FDT is input to the PLL circuit 15 and tuned to the lowest frequency (step 201).

Next, the controller refers to the output SD of the station detector 12 to check whether or not there is a station (step 202).

If there is no station, the tuning frequency is increased by Δf and the above process is repeated. If there is a station, it is checked whether the output voltage Lb of the signal meter 11 is equal to or higher than the set level Ls (for example, 3.5V) (step 203).

If Lb ≧ Ls (= 3.5V), the time to judge whether the receiving station is the RDS station is Ta (for example, 400msec), and if Lb <Ls, the time to judge whether the receiving station is the RDS station is Tb. (Example 8
00msec). After that, it waits for the time Ta or Tb determined based on the magnitude of the received electric field strength to elapse (steps 204 and 205), and when the time elapses, the controller 13
Determines whether the receiving station is an RDS station, depending on whether predetermined RDS data is received from the group synchronization / error detection / correction circuit 10 (step 206).

If it is an RDS station, the seek is ended, and if it is not an RDS station, in other words, if RDS data cannot be demodulated, the process returns to step 201, the tuning frequency is increased by a predetermined frequency Δf, and the seek operation is continued.

<Effects of the Invention> As described above, according to the present invention, the received electric field strength when tuned to a predetermined broadcasting station is detected at the time of seek, and when the received electric field strength is higher than a set level, it is determined whether the receiving station is an RDS station. The judgment time is shortened, and if it is smaller than the set level, the judgment time is lengthened, and after the judgment time elapses, it is judged whether the receiving station is an RDS station. For example, since the seek operation is configured to continue, the time to judge whether the receiving station is an RDS station can be changed according to the received electric field strength, and synchronization can be achieved even when the received electric field strength is low, and seek The total time required can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of an RDS radio receiver that executes RDS seek processing according to the present invention, FIG. 2 is a flow chart of RDS seek processing of the present invention, and FIG. 3 is a flow chart of conventional RDS seek processing. 9 …… RDS decoder / clock recovery circuit 10 …… Group synchronization / error detection / correction circuit 11 …… Signal meter 12 …… Station detector 13 …… Controller 14a …… RDS seek key

Claims (1)

(57) [Claims] 1. An RDS sent superimposed on an FM broadcast signal.
In a seek method of an RDS radio receiver that demodulates data and performs a predetermined operation, during seek, the received electric field strength when tuned to a predetermined broadcasting station is detected, and when the received electric field strength is higher than a set level, reception is performed. The time to judge whether a station is an RDS station is shortened, the judgment time is lengthened if the level is lower than the set level, and the receiving station is judged to be the RDS station after the judgment time has elapsed. A seek method for an RDS radio receiver, which is characterized by continuing the seek operation unless the station is an RDS station.