JPH04103225A - Seek method for rds radio receiver - Google Patents

Abstract

PURPOSE:To reduce the total time required for seek by varying a time for discriminating whether or not a reception station is an RDS(radio data system) station in response to a reception electric field strength. CONSTITUTION:When an RDS seek key 14a is depressed and an RDS seek is requested, a controller 13 brings a tuning frequency into a minimum frequency. That is, a prescribed reception frequency data FDT is inputted to a PLL circuit 15 and tuned to the minimum frequency. Then the controller 13 references an output SD of a station detector 12 to check whether or not a station is in existence. Then the discrimination time is decided based on the magnitude of the reception electric field strength and after the lapse of the time, the reception station discriminates the RDS station and when the reception station is the RDS station, the seek is finished and when the reception station is not the RDS station, the seek is continued. Thus, the total time required for seek is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a seek method for an RDS radio receiver, and particularly to a seek method that can shorten seek time.

<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 put into practical use. This RDS
is a method that superimposes various digital data on FM radio broadcast signals, and the message is (i) Program identification code (PI code) (IT) Broadcasting station name (PS) (UI) of the currently received FM broadcast. ) Frequency list of broadcasting stations broadcasting the same program (AF)
0,) Program content identification code (PTY) (v) Transmission status identification code (DI) (vi) Music or conversation identification code (M/S code) and (vM) Traffic information broadcasting station identification code (vi ) There is an identification code etc. during traffic information broadcast.

In this way, with RDS, messages related to the FM broadcasts being received are transmitted multiplexed.

Using this message, unprecedented channel selection operations are possible. For this reason, in addition to the normal automatic seek, the RDS radio receiver has an RDS seek that skips non-RDS stations and tunes only to RDS stations.

FIG. 3 is a flowchart of such conventional RDS seek control. The RDS seek key is pressed, the tuning frequency is increased or decreased by a predetermined frequency Δf (Step 101), the station detector output is referred to to check whether there is a station (step 102), and if there is no station, Δf is changed. repeat the above process, and if there is a station, wait for a preset time T to elapse (step 103);
After time T has elapsed, it is determined whether the receiving station is an RDS station based on whether RDS data is being received (step 104).
, if the station is an RDS station, the seek ends, and if the station is not an RDS station, the process returns to step 101 and the tuning frequency is set to the predetermined frequency Δ.
Increase or decrease f and repeat the subsequent processing.

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

For this reason, conventionally, the set time T is set to a length long enough to maintain synchronization even if the received field strength is small, for example, 800 m.
It is set to 5ec.

However, if the received electric field strength is large, within a short time,
For example, synchronization can be achieved within about 400m5ec.

Therefore, when the received electric field strength is large, the conventional setting time T = 800 m5ec is too long, and the total R
There was a problem that DS seek required a long time.

From the above, it is an object of the present invention to achieve R
An object of the present invention is to provide a seek method in a DS radio receiver.

Means for Solving the Problems> The above problems are solved in the present invention by providing a seek means, a means for detecting the received electric field strength, and a time period for determining whether or not a receiving station is an RDS station based on the magnitude of the received electric field strength. This is accomplished by a means for determining, an RDS station determining means for determining whether the receiving station is an RDS station, and a seek end/continue instruction means.

Function> When seeking, the received electric field strength when tuned to a predetermined broadcasting station is detected, and the receiving station selects RD based on the magnitude of the received electric field strength.
A time is determined to determine whether the receiving station is an S station, and after the elapse of this time, it is determined whether the receiving station is an RDS station. If it is an RDS station, the seek operation is completed, and if it is not an RDS station, the seek operation is continued.

As described above, according to the present invention, since the time for determining whether a receiving station is an RDS station is varied according to the received electric field strength, synchronization can be achieved even when the received electric field strength is low, and the time required for seeking is Total time can be shortened.

<Embodiment> FIG. 1 is a block diagram of the main parts of a radio receiver that implements the seek 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),
Reference numeral 7 denotes a speaker, which is driven by the amplifier 6 and outputs audio.

8 is a 57KHz bandpass filter (BPF), which is a 57KH bandpass filter that is amplitude modulated based on RDS data.
Pass the subcarrier of z. 9 is an RDS decoder/clock recovery circuit, which outputs the RD from the bandpass filter output.
Demodulates the S data and regenerates the clock. A group synchronization/error detection/correction circuit 10 detects errors in the RDS data demodulated by the RDS decoder/clock recovery circuit 9 while synchronizing each group, and corrects the errors.

Reference numeral 11 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, and when it is within the range of the frequency shift Δf (band l1l) of the received signal and the signal strength is above the set level, a receiving station exists (station present).
It is determined that

13 is a microcomputer-configured controller that performs automatic tracking processing and RDS seek processing to be described later based on RDS data, received electric field strength Lb, station detect signal SD, etc., 14 is an operation unit, and 15 is received 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.

Note that 14a is an RDS seek key for executing RDS seek.

The RDS seek process of the radio receiver of FIG. 1 will be explained below according to the flowchart of FIG. 2.

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

Next, the controller refers to the output SD of the station detector 12 to check whether there is a station (step 202).

If there is no station, the tuning frequency is increased by Δf and the above process is repeated, and 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, 3.5 V) (step 203).

If Lb≧Ls (=3.5V), the time to determine whether the receiving station is an RDS station is Ta (for example, 400m5ec).
If Lb<Ls, the time for determining whether the receiving station is an RDS station is set to Tb (for example, 800+++5 ec).

Thereafter, the process waits for the time Ta or Tb determined based on the magnitude of the received electric field strength to elapse (step 204.
205), when the time has elapsed, the controller 13 determines whether the receiving station is an RDS station based on whether predetermined RDS data is received from the group synchronization/error detection/correction circuit 1o (step 206).

If the station is an RDS station, the seek ends; if the station is not an RDS station, in other words, if the 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> According to the present invention, when seeking, the received electric field strength when tuned to a predetermined broadcasting station is detected, and it is determined whether the receiving station is an RDS station based on the magnitude of the received electric field strength. After the time has elapsed, it is determined whether the receiving station is an RDS station, and the RD
If the station is an S station, the seek ends, but if the station is not an RDS station, the seek operation is continued. Therefore, the time taken to determine whether the receiving station is an RDS station can be varied depending on the received field strength, and the receiving Synchronization can be achieved even when the electric field strength is low, and the total time required for seeking can be shortened.

[Brief explanation of the drawing]

FIG. 1 shows R that executes RDS seek processing according to the present invention.
A block diagram of the DS radio receiver, FIG. 2 is the RD of the present invention.
Flow chart of S seek processing, FIG. 3 is a flow chart of conventional RDS seek processing. 9...RDS decoder/clock regeneration circuit 10...Group synchronization/error detection/correction circuit 11...Signal meter 12...Station detector 13...Controller 14a...RDS seek key Patent applicant Alvine Co., Ltd. Agent Patent attorney Saito Thousand trunks diagram 2

Claims (1)

[Claims] In a seek method for an RDS radio receiver that demodulates RDS data sent superimposed on an FM broadcast signal and performs a predetermined operation, the received electric field when the RDS radio receiver is tuned to a predetermined broadcast station at the time of seek. Determine the time to determine whether the receiving station is an RDS station based on the magnitude of the received electric field strength, determine whether the receiving station is an RDS station after the elapse of this time, and if it is an RDS station, seek. A seek method for an RDS radio receiver, characterized in that if the station is not an RDS station, the seek operation is continued.