JP2603750Y2 - 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 that performs automatic tuning using an AF list in a radio data system (hereinafter, referred to as RDS).

[0002]

2. Description of the Related Art RDS is a system described in the European Broadcasting Union Technical Specification (EBU document 3244), and in the function of this system, another program which broadcasts the same program as the program currently being received. A function is included to notify a radio receiver capable of receiving RDS data that a frequency is assigned to a broadcast station. Therefore, by using this function, if a stronger signal can be obtained in the radio wave of another broadcasting station broadcasting the same program, the reception of the radio receiver can be switched to that reception. . Therefore, the radio receiver receives and stores the code of the alternative frequency (referred to as an AF code) transmitted for the above function, and searches for a list of stored AF codes, that is, an alternative frequency list (referred to as an AF list) ( AF search) is performed.

[0003]

In an AF search in a conventional radio receiver, only the electric field strength of an alternative station is compared, and switching is made to broadcast reception of a broadcast station having a large electric field strength. However, there is a problem that even if the electric field strength is large, the adjacent interference is large, and it is not always the case that the best reception can be achieved by selecting the broadcast reception of the broadcasting station having the large electric field strength.

An object of the present invention is to provide a radio receiver capable of automatically selecting one receivable station having the best reception (low noise and low distortion) at a frequency in an AF list.

[0005]

Radio receiver school draft Means for Solving the Problems] selectively a broadband intermediate frequency filter is switched and narrow band region intermediate frequency filter as an intermediate-frequency filter,
In a radio receiver having a search function of searching for an alternative frequency station in an alternative frequency list included in data of a radio data multiplex broadcasting system, an electric field intensity and noise level detecting means, and a broadband intermediate frequency filter in a receiving station search First selecting means for selecting a broadcast station having the maximum electric field strength among the detected electric field strengths as a receiving station when the detected noise level is equal to or lower than a first predetermined value in the selected state; When the level is not equal to or less than the first predetermined value, a broadcast station having a detection noise level equal to or lower than the second predetermined value and a detection electric field intensity equal to or higher than the predetermined value and having the next highest electric field intensity is selected. A second selecting means as a receiving station, when the detected electric field strength is less than a predetermined value, or when the detected noise level exceeds a second predetermined value. Rutoki changes the intermediate frequency filter in a narrow band intermediate frequency filter, characterized in that a third selecting means for a receiving station by selecting the field strength up to broadcasters.

[0006]

According to the radio receiver of the present invention, when the detected noise level is lower than the first predetermined value, the broadcasting station having the maximum electric field strength in the detected electric field strength is selected as the receiving station.
When the detected noise level is not equal to or lower than the first predetermined value, the broadcast station having the detected noise level equal to or lower than the second predetermined value and the detected electric field intensity equal to or higher than the predetermined value and the electric field intensity next to the maximum electric field intensity Is selected as the receiving station. In this case, the electric field intensity is not the maximum, but is not less than the predetermined value, and the noise perception does not deteriorate, and the noise level is small, so that the Hi-Fi characteristics can be maintained. When the detected electric field strength is less than the predetermined value or when the detected noise level exceeds the second predetermined value, the intermediate frequency filter is changed to a narrow band, and the broadcasting station having the highest electric field strength is selected as a receiving station. In this case, it is determined that adjacent interference has occurred, and the broadcast station having the maximum electric field strength is selected with the intermediate frequency band switched to a narrow band and the adjacent interference removed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG.
FIG. 2 is a block diagram showing a configuration of an embodiment of the present invention.Book
Invented the radio as a data multiplex broadcasting system for radio
A data system (hereinafter referred to as RDS) is described as an example.
You.

A front end 2 for receiving and amplifying a reception frequency by receiving an output signal from the antenna 1, and selecting a reception frequency in the output signal from the antenna 1 in cooperation with the front end 2, and as a local oscillator A frequency synthesizer 3 having a PLL configuration that operates to convert a reception frequency to an intermediate frequency, an intermediate frequency amplification circuit 4 having a wideband intermediate frequency filter 41 and a narrowband intermediate frequency filter 42 selectively inserted into the circuit, and an intermediate frequency amplification circuit An FM demodulation circuit 5 that demodulates the output of the circuit 4 and a stereo demodulation circuit 6 that receives the FM demodulation output and separates the signal into left and right audio signals are provided. Perform the receiving action to play.

Further, an electric field intensity detecting circuit 7 for receiving an output from a middle stage of the intermediate frequency amplifying circuit 4 and detecting an electric field intensity.
A noise level detection circuit 8 for detecting a noise level from the FM demodulation output, an RDS demodulation circuit 9 for demodulating RDS information from the FM demodulation output and outputting RDS data in synchronization with a bit rate of the RDS information, and a RAM 10. And receives and processes the electric field intensity signal detected by the electric field intensity detection circuit 7, the noise level signal detected by the noise level detection circuit 8, and the RDS data output from the RDS demodulation circuit 10, and a part of the frequency synthesizer 3. Control the frequency division ratio of the frequency divider that constitutes
And a microcomputer 11 for controlling the switching between the broadband intermediate frequency filter 41 and the narrowband intermediate frequency filter 42 in FIG.

Here, the microcomputer 11 is connected to the RA
Functionally, in cooperation with M10, in the receiving station search, the broadband intermediate frequency filter 41 is selected, and when the detected noise level is equal to or less than the predetermined value a, the broadcasting station having the maximum electric field strength among the detected electric field strengths is selected. Selecting means 12 to be a receiving station
When the detected noise level is not less than the predetermined value a, the detected noise level is not more than the predetermined value b (a ≧ b), and the detected electric field strength is not less than the predetermined value α. Second selecting means 13 for selecting a broadcasting station having the next largest electric field strength after the maximum electric field strength to be a receiving station
When the detected electric field strength is less than the predetermined value α, or when the detected noise level exceeds the predetermined value b, the intermediate frequency filter is changed to the narrow band intermediate frequency filter 42 and the broadcast station having the maximum electric field strength is selected. And a third selecting means 14 serving as a receiving station.

The operation of the embodiment constructed as described above will be described with reference to the flowchart of FIG.

When the AF search is started, one AF code is read from the AF list stored in the RAM 10, and a part of the frequency synthesizer 3 is divided into a frequency division ratio corresponding to the read AF code. The frequency division ratio of the frequency divider to be configured is set (step S1). Subsequent to step S1, it is checked whether or not the radio wave is from the broadcast station by the station determination. If it is determined that the radio wave is not from the broadcast station, step S1 is repeated until it is determined that the radio wave is from the broadcast station. (Step S2).

If it is determined in step S2 that the signal is a radio wave from a broadcasting station, the wide-band intermediate frequency filter 41 is selected and inserted and connected to the intermediate frequency amplifier circuit 4 (step S3). The data is read and stored in the RAM 10 corresponding to the AF code (step S4).
Steps S1 to S3 are executed until all the AF codes in the AF list are reached (step S5). Therefore,
When the processing is performed over all the AF codes in the AF list, the RAM 10 stores the electric field intensity signal and the noise level signal of the broadcasting station corresponding to all the AF codes corresponding to each broadcasting station.

When it is determined in step S5 that the execution has been performed for all AF codes, the process proceeds to step S3.
In step S, the electric field intensity signal stored in the RAM 10 is compared to select the broadcast station having the maximum electric field intensity (step S).
6) It is checked from the noise level signal at the time of broadcast reception of the selected broadcast station whether the noise level is equal to or less than a predetermined value a (step S7). When it is determined in step S7 that the noise level is equal to or lower than the predetermined value a, the AF search ends, and the broadcasting station corresponding to the AF code selected in step S6 is selected as a receiving station.

If it is determined in step S7 that the noise level is not lower than the predetermined value a, a station having the next highest electric field strength is selected following step S7 (step S7).
8) It is checked whether the electric field strength of the radio wave from the broadcasting station selected in step S8 is equal to or more than a predetermined value α (step S9).

If it is determined in step S9 that the electric field strength is equal to or higher than α, it is checked whether the noise level is equal to or lower than a predetermined value b (step S9).
10). If it is determined in the check in step S10 that the noise level is equal to or lower than the predetermined value b (a ≧ b), the AF search is terminated, the noise level is equal to or lower than the predetermined value b, and the electric field strength is lower than the predetermined value α. The broadcasting station having the above-described electric field strength next to the maximum electric field strength is selected as the receiving station.

If it is determined in step S9 that the electric field strength is not higher than α, and if it is determined in step S10 that the noise level is not lower than the predetermined value α, the wideband intermediate frequency filter 41 Switching to the band intermediate frequency filter 42 (step S11), the broadcasting station with the highest electric field strength selected in step S6 is selected as the receiving station (step S12), and the AF search ends.

As described above, when (a) the noise level is equal to or lower than the predetermined value a, the broadcasting station having the maximum electric field intensity is selected, and (b) even when the electric field intensity is maximum, the noise level is equal to the predetermined value a.
If not, a broadcasting station having a noise level equal to or lower than a predetermined value b, an electric field intensity equal to or higher than a predetermined value α, and an electric field intensity next to the maximum electric field intensity is selected. When the value is less than the value α or when the noise level exceeds the predetermined value b, the intermediate frequency band is changed to a narrow band, and the station having the highest electric field strength is selected as the receiving station.

Here, when the noise level is equal to or lower than the predetermined value a, the station having the maximum electric field strength is selected. This case corresponds to the above (a). Next, the electric field intensity is not the maximum, but if the electric field intensity is equal to or higher than the predetermined value α, the noise perception does not deteriorate. A broadcast station having a field strength equal to or larger than the predetermined value α and next to the maximum field strength is selected. By doing so, the Hi-Fi property can be maintained. This case corresponds to the above (b). Also,
When the electric field strength is less than the predetermined value α, or when the noise level exceeds the predetermined value b, the radio wave of the broadcasting station is regarded as receiving adjacent interference, and the intermediate frequency band is switched to a narrow band to remove the adjacent interference. To select the broadcast station with the highest electric field strength. This case corresponds to the above (c).

[0020]

As described above, according to the present invention, when the noise level is equal to or less than the first predetermined value in the receiving station search, the station having the maximum electric field strength is selected and the noise level is set to the first level.
If the noise level is not less than the second predetermined value, a broadcast station having a detected field strength equal to or more than the predetermined value and the next largest electric field strength after the maximum electric field strength is selected. When is less than a predetermined value, or when the detected noise level exceeds a second predetermined value, the intermediate frequency band is changed to a narrow band, and the broadcast station having the highest electric field strength is selected to be a receiving station. Thus, there is an effect that one station that can ensure the best reception quality is selected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment of the present invention;

[Explanation of symbols]

 2 Front End 3 Frequency Synthesizer 4 Intermediate Frequency Circuit 7 Electric Field Strength Detection Circuit 8 Noise Level Detection Circuit 9 RDS Demodulation Circuit 10 RAM 11 Microcomputer 12 First Selection Means 13 Second Selection Means 14 Third Selection Means 41 Broadband Intermediate Frequency Filter 42 Narrowband intermediate frequency filter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H03J 7/18 H03J 5/00-5/02 H04B 1/16

Claims (1)

(57) [Scope of request for utility model registration] And a 1. A intermediate frequency wideband intermediate frequency filter and narrow band region intermediate frequency filter selectively be switched as a filter, a station of an alternative frequency in the alternative frequency list contained in the data of the radio data multiplex broadcasting system In a radio receiver having a search function for performing a search, an electric field strength and noise level detecting means, and a detecting station, when a detected noise level is equal to or lower than a first predetermined value in a wide band intermediate frequency filter selected state, the detected electric field strength and noise level are detected. First selecting means for selecting a broadcasting station having the maximum electric field strength as a receiving station, and when the detected noise level is not equal to or less than the first predetermined value when the broadband intermediate frequency filter is selected, the detected noise level is equal to or less than the second predetermined value And the detected electric field strength is equal to or higher than a predetermined value and the broadcast station having the next highest electric field strength is selected. A second selecting means for selectively selecting a receiving station; and changing the intermediate frequency filter to a narrow band intermediate frequency filter when the detected electric field strength is less than a predetermined value or when the detected noise level exceeds a second predetermined value. And a third selecting means for selecting the broadcast station having the maximum electric field strength as a receiving station.