JP3929764B2 - Radio receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio receiver having a broadcast station automatic search function for automatically searching for and receiving a broadcast station having a good reception state.
[0002]
[Prior art]
Conventionally, there has been known an electronic tuning radio receiver with a broadcast station automatic search function that automatically searches for a broadcasting station having a good reception state and receives a broadcasting station having a good reception state. As shown in the flowchart of FIG. 3, the broadcast station automatic search operation of the machine determines whether or not the start of the broadcast station automatic search is requested during reception of the frequency f (step 31) (step 32). If the start of the station automatic search is not requested, reception of the frequency f is continued.
[0003]
When the start of the broadcast station automatic search is requested, the output audio signal is muted (step 33), and the frequency change unit at the time of the automatic broadcast station search set in advance to the frequency f being received is 1 step. And the added frequency is newly set as f (step 34).
[0004]
Next, the frequency f is tuned to the added frequency f (step 35), the electric field strength V of the tuning frequency is confirmed, and the minimum required to determine a good reception state at the time of automatic broadcast station search in which the electric field strength V is preset. It is determined whether or not the electric field intensity Va is equal to or higher than that (step 36). If the electric field intensity V is smaller than Va, the process returns to step 34, and the frequency is added and the process is repeated.
[0005]
If the electric field strength V is equal to or greater than Va, the presence / absence of an IF (Intermediate Frequency) signal having a tuning frequency f is confirmed (step 37). If there is no IF signal, the process returns to step 34 to further add the frequency. repeat.
[0006]
If there is an IF signal, the mute of the audio signal is canceled and the received audio of frequency f is output (step 38). In this way, a broadcast station having a frequency at which the electric field intensity V of the tuning frequency is equal to or higher than the minimum electric field intensity Va is searched for as a broadcast station having a good reception state.
[0007]
[Problems to be solved by the invention]
However, in such a conventional electronically tuned radio receiver with automatic broadcast station search function, especially in areas where there is a strong electric field, such as an area where the broadcast station is nearby, frequencies other than the strong electric wave Due to the reception characteristics that the apparent electric field strength is reduced by being suppressed by strong radio waves, even a broadcasting station with a good reception condition is judged to be a broadcasting station with a low electric field strength and a poor reception condition. There are things that cannot be done.
[0008]
In such a case, there is a problem that a broadcast station in a good reception state cannot be searched by automatic search until it is not subjected to strong radio wave suppression.
[0009]
The present invention has been made to solve such problems, and provides a radio receiver capable of searching for a broadcasting station in a good reception state without being affected by a radio wave environment.
[0010]
[Means for Solving the Problems]
A radio receiver according to the present invention receives and detects a radio wave having a tuned reception frequency, detects a field strength of the detected received signal, and a signal having a frequency with a field strength stronger than a preset field strength. A detection circuit that detects the presence of a signal, and a control that sequentially changes the reception frequency to search for a signal having a frequency of electric field strength equal to or higher than a preset minimum electric field strength, and receives a radio wave of a broadcast station of the searched frequency The broadcast station search means is configured to change the minimum electric field intensity when the detection circuit detects that there is a signal having a frequency equal to or higher than a preset reference electric field intensity. Have. With this configuration, when the detection circuit detects that there is a signal having a strong electric field strength frequency, the minimum electric field strength is changed.
[0011]
Here, it is preferable that the detection circuit is an AGC circuit that attenuates a received signal when the electric field intensity exceeds a preset electric field intensity.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
1 and 2 are diagrams showing a configuration and processing procedure of a radio receiver according to an embodiment of the present invention.
[0014]
As shown in FIG. 1, the radio receiver according to the present embodiment is controlled by a control microcomputer 11 that controls the operation of the radio receiver including broadcast station search means and the like. An electronically tuned radio receiver circuit (receiver circuit) 12 that tunes to the frequency and notifies the control microcomputer 11 of the presence / absence of the IF signal and the electric field strength, detects a radio wave of the received broadcast station, and outputs an audio signal, and a control microcomputer 11, a mute circuit 13 for muting the audio signal from the electronic tuning radio reception circuit 12, an amplifier 14 for amplifying the audio signal from the electronic tuning radio reception circuit 12, and the audio signal amplified by the amplifier 14 are converted into sound. A speaker 15 is provided. The electronic tuning radio reception circuit 12 detects the electric field strength of a part of a frequency within a preset band (for example, a frequency band in which the electronic tuning radio reception circuit 12 can be tuned), and a preset reference electric field strength. AGC (Auto Gain Control) circuit (detection circuit) 12a for attenuating the received signal when the signal exceeds the limit.
[0015]
In this radio receiver, at the time of automatic broadcast station search, the control microcomputer 11 determines whether the AGC circuit 12a is operating by detecting the frequency of the strong electric field, and the AGC circuit is operating (being under a strong electric field). In this case, the minimum electric field strength necessary for determining a good reception state is changed.
[0016]
Specifically, as shown in the flowchart of FIG. 2, the control microcomputer 11 determines whether the start of the broadcast station automatic search is requested during reception of the frequency f (step 11) (step 12). If the start of the broadcast station automatic search is not requested, reception of the frequency f is continued.
[0017]
When the start of the broadcast station automatic search is requested, the audio signal to be output is muted (step 13), and the preset frequency change unit at the time of automatic broadcast station search is added to the frequency f being received. Then, the added frequency is newly set as f (step 14).
[0018]
Next, tuning is performed to the added frequency f (step 15), and the value Va1 in the normal state is set as the minimum electric field intensity Va necessary for determining a good reception state during the broadcast station automatic search (step 16).
[0019]
Next, the control microcomputer 11 inquires of the electronic tuning radio reception circuit 12 whether the tuning frequency is a strong electric field and the AGC circuit 12a operates to attenuate the input signal (step 17), and the AGC circuit 12a operates. Then, the minimum electric field strength Va is changed to a value (a value lower than Va1) Va2 corresponding to the strong electric field (step 18).
[0020]
Next, the electric field strength V at the tuning frequency is confirmed to determine whether the electric field strength V is equal to or higher than the minimum electric field strength Va (step 19). If the electric field strength V is smaller than Va, the process returns to step 14 and the frequency is added and processed. repeat.
[0021]
If the electric field strength V is equal to or greater than Va, the presence / absence of the IF signal having the tuning frequency f is confirmed (step 20). If there is no IF signal, the process returns to step 14 to add the frequency and repeat the process.
[0022]
If there is an IF signal, the mute of the audio signal is canceled and the received audio of frequency f is output (step 21).
[0023]
As described above, the radio receiver according to the present embodiment has a minimum electric field for determining a good reception state depending on whether or not the AGC circuit 12a is operating when the control microcomputer 11 performs the automatic broadcast station search. Since the value of the intensity Va is changed, it is possible to automatically search for a broadcasting station in a good reception state even under a strong electric field.
[0024]
In the present embodiment, the AGC circuit 12a detects whether the electric field is stronger than the reference electric field intensity. When the electric field is detected to be under the strong electric field, the minimum electric field intensity Va is changed. For example, the effect amount (attenuation amount) of the AGC circuit may be monitored, and the minimum electric field strength Va may be switched in a plurality of stages depending on the value of the effect amount (attenuation amount).
[0025]
【The invention's effect】
As described above, according to the present invention, a strong electric field is detected when performing a broadcast station automatic search operation, and the minimum electric field strength for determining that the reception state is good is low suitable for a strong electric field. By changing the value, it is possible to automatically search for a good broadcasting station without being affected even under a strong electric field .
[Brief description of the drawings]
FIG. 1 is a schematic block diagram illustrating a radio receiver according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating an automatic broadcast station search operation of the radio receiver according to an embodiment of the present invention. Flow chart showing automatic broadcast station search operation of electronically tuned radio receiver [Explanation of symbols]
11 Control microcomputer (Broadcasting station search means)
12 Electronically tuned radio receiver circuit (receiver circuit)
12a AGC circuit (detection circuit)
13 Mute circuit 14 Amplifier 15 Speaker

Claims (1)

A control microcomputer and a reception circuit that is controlled by the control microcomputer and receives and detects a radio wave of a tuned reception frequency, and detects a field intensity of the detected reception signal ;
The receiving circuit includes an AGC circuit that detects an electric field strength of the detected received signal and attenuates the received signal when a predetermined reference electric field strength is exceeded,
The control microcomputer sequentially changes the reception frequency to search for a signal having a frequency of electric field strength equal to or higher than a preset minimum electric field strength, receives a radio wave of a broadcast station having the searched frequency, and the AGC circuit When detecting the signal of the set reference electric field strength or more frequencies, radio receiver and changes the minimum electric field strength in the preset value lower than the lowest field strength.

Images