JP2860244B2 - Radio receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiver, and more particularly to a radio receiver capable of performing a high-speed AF search when exiting a tunnel.

[0002]

2. Description of the Related Art An RDS (Radio Data System) for digitally multiplexing channel selection data and program identification data to an FM radio broadcast signal to provide various services to a vehicle driver.
tem) has been widely put into practical use in Europe and is expected to spread worldwide. Typical RDS
The services include a PI (program identification) service for identifying a country, a reception area, and a program name of a broadcast station, a PS (reception station name display) service for displaying a received broadcast station name on a tuner display, and the same content. There are an AF (similar program broadcast frequency list) service for displaying the frequency of another broadcast station broadcasting a program, a TP service for identifying a broadcast station of traffic information, and the like.

[0003] The AF service is provided with a search function for receiving another broadcasting station radio wave of the same program broadcast when the received electric field strength of the RDS radio wave transmitted from the broadcasting station by the in-vehicle tuner falls below a certain level. ing. This search is performed on the basis of the AF list transmitted from the broadcast station stored in the memory in advance and based on the stored AF list.

[0004] For example, when the radio wave intensity from a certain broadcasting station becomes weak while driving in an automobile, the AF received in the reception area concerned becomes weak.
Other stations transmitting the same broadcast content are automatically received based on the list. At that time, the AF list stored in the vehicle-mounted memory is updated to the AF list received in the area.

[0005]

As described above, the AF service processing of the conventional RDS radio receiver is executed.
By the way, normally, it is not possible to receive radio waves from a broadcasting station in a good state in a tunnel. Therefore, when the user enters the tunnel from a state where radio waves from a specific RDS station have been well received, the electric field strength of the received radio waves is significantly reduced, so that an AF search based on the AF list is started. At this time, since the radio wave from the broadcasting station cannot be received with a sufficient electric field strength, the AF search operation is not completed, and a PI search process for searching for a PI code is performed. This PI
The search is to search for a station that matches the PI code of the station that has been received so far, and the process of sequentially searching from the lower limit to the upper limit of the scheduled broadcast station frequency is continued.

[0006] During the above PI search process in the tunnel, if the user escapes from the tunnel and the radio wave reception condition becomes good, the user wants to set the frequency received before entering the tunnel again. , It takes a long time to search for a desired broadcasting station by the search, and it is impossible to perform a high-speed AF search when exiting a tunnel.

An object of the present invention is to provide a radio receiver capable of quickly searching for a receiving station when exiting a tunnel.

[0008]

In order to solve the above-mentioned problem, a radio receiver according to the present invention receives RDS data, stores an AF list included in the RDS data in a memory, and stores the AF list in the memory. In an RDS receiver having an AF search function for automatically switching to a station with a good reception state based on the AF list, it is determined that the user has entered the tunnel. The apparatus is configured to perform the AF search process including the frequency received before entering, and receive a station in a good reception state.

[0009]

According to the present invention, the RDS receiver has an AF search function, and performs AF search processing after entering the tunnel and exiting the tunnel, including the frequency received before entering the tunnel. This enables a quick search for a receiving station when exiting a tunnel.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing an operation processing procedure of an embodiment of a radio receiver according to the present invention.
FIG. 2 is a configuration block diagram of a radio receiver for realizing the present embodiment.

First, the configuration of the radio receiver according to the present embodiment will be described with reference to FIG. 2. A reception signal received by an antenna 1 is converted into an IF signal by a front end 2. The front end 2 incorporates a voltage controlled oscillator (VCO) and a mixer, and sets a reception frequency based on a control signal from the microcomputer 9 in cooperation with the PLL circuit 3. The converted IF signal is detected by an IF detection circuit (IF / DET) 4 and then a volume circuit 5
Is used to adjust the volume.

The output of the IF detection circuit 4 is detected by a reception sensitivity detection circuit 7 as the reception sensitivity, for example, as an electric field intensity, and sent to a microcomputer 9. The RDS data demodulation circuit 8 demodulates the detection signal from the IF detection circuit 4 and sends out the obtained RDS data to the microcomputer 9.

The microcomputer 9 receives the sensitivity signal from the reception sensitivity detection circuit 7 and the RDS data from the RDS data demodulation circuit 8 and performs the above-mentioned RDS service.
The RAM 10 is a memory for storing an AF list included in the received RDS data.
To read and update.

The mute circuit 6 performs a mute process on the audio signal from the volume circuit 5 under the control of the microcomputer 9. The audio signal that has passed through the mute circuit 6 is output from the speaker 12 after being amplified by the output amplifier 11.

In the present embodiment, the microcomputer 9 performs the AF search processing of the RDS receiver at the time of exiting the tunnel. The processing procedure will be described below with reference to FIG.

First, it is determined whether or not the FM reception sensitivity is less than 5 dB (step S1). If it is less than 5 dB, it is determined whether or not the previous state was outside the tunnel (step S1).
2). Here, 5 dB is an example and can be set arbitrarily. If the previous state was outside the tunnel, you can recognize that you were inside the tunnel and 20 seconds (can be set arbitrarily)
It is determined whether or not the state does not change (step S3). If the state does not change, the fact that the state is within the tunnel is stored (step S4). After that, the process ends. In steps S2 and S3, the previous state is not outside the tunnel,
If the state change has not continued for 20 seconds, the process is terminated.

In step S1, the FM reception sensitivity is 5
If it is determined that it is equal to or more than dB, it is determined whether or not the previous state is within the tunnel (step S5). Is determined (step S
6). Here, if the FM reception sensitivity is 15 dB or more,
The state outside the tunnel is stored (step S7), the start of all AF search is requested (step S8), and the process ends. The full AF search referred to here is an AF search performed including the frequency before entering the tunnel. In steps S5 and S6, if the previous state is not inside the tunnel and the FM reception sensitivity is less than 15 dB, the processing is terminated as it is. The above processing is usually performed once per second.

In this embodiment, the conventional receiver performs the PI search even when exiting the tunnel, but determines that the user has entered the tunnel, and then determines that the user exits the tunnel. Since the AF search is performed including the frequency before entering, the receiving station can be quickly acquired even when exiting the tunnel.

[0019]

As described above, according to the radio receiver of the present invention, a broadcasting station which has been received before entering the tunnel or a broadcasting station having the same contents is quickly searched when leaving the tunnel. be able to.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation processing procedure of an embodiment of a radio receiver according to the present invention.

FIG. 2 is a configuration block diagram of a radio receiver for realizing the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 Front end 3 PLL circuit 4 IF detection circuit 5 Volume circuit 6 Mute circuit 7 Reception sensitivity detection circuit 8 RDS data demodulation circuit 9 Microcomputer 10 RAM 11 Output amplifier 12 Speaker

Claims (1)

(57) [Claims] An AF search for receiving RDS data, storing an AF list included in the RDS data in a memory, and automatically switching to a station having a good reception state based on the AF list stored in the memory. In the RDS receiver having the function, when it is determined that the vehicle has entered the tunnel, and when it is determined that the vehicle has escaped from the tunnel, the AF search process including the frequency received before entering the tunnel is performed, and the reception state is determined. Radio receiver characterized by receiving good stations.