JPH04246907A - Search method for alternate frequency for on-vehicle radio receiver - Google Patents

Abstract

PURPOSE:To realize the search method of the alternate frequency of an on- vehicle radio receiver, by which the number of times of the search is reduced, and the alternate frequency in a satisfactory received state can be speedily obtained. CONSTITUTION:When a receiving sensitivity detecting means 8 detects that the radio wave of a receiving station is less than a fixed level, an alternate frequency retrieving means 11 changes the frequency division ration of a PLL circuit 3 based on AF data in an RAM 12, and successively operates the search operation of a broadcasting station. At the time of the search, the alternate frequency retrieving means 11 first searches the frequency received before the search operation.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to Radio Dat.
a System data can be received, and
The present invention relates to a method of searching for an alternative frequency for a vehicle-mounted radio receiver, which makes it possible to search for an alternative frequency for the frequency that is being received.

0002

[Prior Art] Conventional Radio Data System
An in-vehicle radio receiver that is capable of receiving TEM (hereinafter referred to as RDS) data searches for a station with good reception when the radio waves of the broadcasting station it is receiving falls below a predetermined level, and selects that broadcasting station. It is designed to receive radio waves.

[0003] Now, the above-mentioned alternative frequency search is performed using RD.
This is done based on the AF data (similar program broadcasting frequency list) of S data, but in areas where the service area switches from station A to station B, the radio waves of station A may be strong or the radio waves of station B may be strong as the vehicle moves. It often happens that the radio waves are strong.

[0004] In such a situation, even if an alternative frequency is searched, stations A and B are often repeatedly received.
In particular, when there is a large amount of AF data, it takes time to find a station with good reception, and during the search, to remove noise, there is a mute state (no sound output) for a short time. Because of the similar structure, there was also the drawback that the sound would break out at regular intervals, making it harsh on the ears.

[0005]

[Problem to be solved by the invention] This invention was made in view of the above points, and its purpose is to reduce the number of searches and quickly find an alternative frequency with good reception. An object of the present invention is to provide a method of searching for an alternative frequency for a vehicle-mounted radio receiver.

[0006]

[Means for Solving the Problems] A search method for an alternative frequency for a car radio receiver according to the present invention is based on Radio D
In an in-vehicle radio receiver that can receive data from the ATA System and search for an alternative frequency to the frequency currently being received, at the time of the search, at first,
This is to search the frequency that was being received before starting the search operation.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method of searching for an alternative frequency for a vehicle-mounted radio receiver according to the present invention will be described with reference to FIGS. 1 and 2.

In the figure, 1 is Radio Data S
2 is a front end having a high frequency amplification section that amplifies the radio waves received by antenna 1 and a mixer section that converts them to a predetermined intermediate frequency; 3 is a front 4 is an intermediate frequency amplification circuit including a detection circuit; 5 is a volume volume adjuster for adjusting the level of the detection output of the intermediate frequency amplification circuit 4; 6 is an audio amplifier; 7 is a volume volume 5 is a muting circuit provided between the intermediate frequency amplifying circuit 4 and the audio amplifier section 6; RDS data demodulation means demodulates RDS data from the output; 10 is a microcomputer that controls this in-vehicle radio receiver; 11 is a microcomputer 10;
Reference numeral 12 is a RAM for storing alternative frequency data (AF data) and necessary data for the broadcasting station being received.

In the in-vehicle radio receiver configured as described above, when the receiving sensitivity detecting means 8 detects that the radio waves of the station being received have fallen below a certain level, the alternative frequency searching means 11 searches for the radio waves in the RAM 12. PL based on AF data
By changing the frequency division ratio (hereinafter referred to as N value) of L circuit 3,
A search operation for broadcasting stations is performed sequentially, and during the search, a mute circuit 7 is operated to prevent noise from being generated in the audio amplifier section 6.

FIG. 2 is a diagram showing the memory structure of the in-vehicle radio receiver of the present invention.

[0011] At addresses A1 to A7 of the RAM 12, N values (N1 to N7) corresponding to the received AF data are stored.
) are stored respectively, and the P address (pointer) stores the address where the N value of the frequency received before entering the search operation is stored.

Next, the operation of the present invention will be explained based on the flowchart of FIG.

When the reception sensitivity detection means 8 detects that the radio waves of the broadcasting station being received have fallen below a predetermined level (step S1), the N value being received is saved (step S2).
, then PL the N value (N3 in Figure 2) indicated by the pointer.
The signal is sent to the L circuit 3 (step S3).

[0014] When a broadcasting station of the alternative frequency of the above N value is received and the radio waves of this broadcasting station are above a predetermined level (step S4), the saved N value is returned to the AF data (step S5), and this AF The address of the data is stored in the pointer (step S6).

Now, if the reception level is below the predetermined level in step S4, the pointer is advanced (in FIG. 2, the content of address P is set to A4) (steps S7, S8), and the N value indicated by the pointer (in FIG. 2, N4) is sent to the PLL circuit 3 (step S9). Then, the reception state in this state is checked.

[0016] In this way, steps S4, S7, S8, S
9 is repeated in order to search based on the AF data, and eventually, when it is detected that the received station's radio waves are at a predetermined level or higher (step S4), step S2
Return the N value saved in step S5 to the AF data,
The address of this AF data is stored in the pointer (step S6).

[0017] In the present invention, if a broadcasting station with good reception condition cannot be found even after searching all the AF data, the search operation is terminated.

[0018]

[Effects of the Invention] According to the method of searching for an alternative frequency for a car radio receiver according to the present invention, which is configured as described above, in areas where the service area is switched from station A to station B, it is difficult for vehicles to move. As a result, reception from stations A and B is repeated.

[0019] Therefore, since a search operation based on AF data is not immediately performed, it is possible to quickly receive a station with a good reception condition, and discomfort such as audio cut-out caused by the search operation is also reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an in-vehicle radio receiver according to the present invention.

FIG. 2 is a diagram showing a memory structure of a RAM.

FIG. 3 is a flowchart of main parts.

[Explanation of symbols]

11 Alternative frequency search means

Claims (1)

[Claims] [Claim 1] Radio Data System
In a car radio receiver that is capable of receiving em data and searching for an alternative frequency to the frequency currently being received, when searching, the frequency that was being received before entering the search operation is initially searched. A method of searching for an alternative frequency for an in-vehicle radio receiver.