JPH04273725A - Radio receiver - Google Patents

Abstract

PURPOSE:To make the interruption o a reproduced tone inconspicuous and to moderate difficulty to listen by performing the detecting operation of specific broadcast when the level of a demodulation signal in a broadcast wave being received is low. CONSTITUTION:A level detection circuit 8 which detects the level of the detection output of a detection circuit 4 i.e., that of an audio signal, and a comparator 9 which compares the output signal of the level detection circuit 8 with a prescribed level and outputs a comparison result to a microcomputer 7 are provided. When it is judged that the level of the audio signal goes less than the prescribed value by the comparator 9, the microcomputer 7 performs the detecting operation of the specific broadcast. In other words, the detecting operation is performed when the level of the audio signal of the broadcast wave being received goes down.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a radio receiver.
In particular, the present invention relates to a radio receiver that monitors specific broadcasts such as traffic information broadcasts and receives the specific broadcasts when the specific broadcasts are detected.

0002

[Prior Art] Conventionally, traffic information broadcasting, 1620 and 1629 KHz broadcasting broadcast on expressways in Japan, traffic information broadcasting in which traffic information identification signals are added to broadcast waves broadcasted in Europe, and BACKGROUND ART Broadcasting is carried out in which data indicating the content being broadcast is added to broadcast waves called a radio data system, and is often used while driving a car. In consideration of operability while driving a car, there is a radio receiver that automatically switches to traffic information broadcasting when traffic information is detected. The following will explain traffic information broadcasting at 1620 and 1629 KHz, which is broadcast on expressways in Japan, as an example.

FIG. 3 is a block diagram showing a conventional radio receiver. The radio receiver includes an antenna 1, a high frequency amplification circuit, and a front end (F/E) 2 consisting of a mixing circuit that mixes a local oscillation signal from a local oscillation circuit with the output of the high frequency amplification circuit.
, an intermediate frequency amplification circuit (IF) 3 that amplifies the intermediate frequency signal frequency-converted by the mixing circuit, and a dual-purpose detection circuit (DET) 4 that converts the output signal from the intermediate frequency amplification circuit 3 into an audio signal. , an amplifier 5 that amplifies the audio signal from the detection circuit 4 and outputs it from the speaker 6.

[0004] The microcomputer 7 performs various controls of the receiver and controls the receiving frequency. The reception frequency is controlled by outputting a signal instructing the reception frequency to the front end 2. This controls the oscillation frequency of the local oscillation circuit of the front end 2, and the PLL that makes up the local oscillation circuit
This is done by outputting the frequency division ratio to the variable frequency divider circuit in the circuit.

[0005] Broadcast waves are detected using an output signal of the front end 2 called a signal level signal, that is, a signal indicating the level of the output signal of the intermediate frequency amplification circuit. This signal level signal is obtained by detecting the output signal of the front end 2.

In the radio receiver shown in FIG.
In order to monitor traffic information broadcasting, it is necessary to detect broadcast waves at predetermined time intervals by setting the reception frequency to 1620 (1629) KHz. For this reason, this radio receiver has a problem in that the sound of the radio broadcast being received is interrupted during the detection operation of the traffic information broadcast, making it difficult to hear.

FIG. 4 shows a solution to the problem of the radio receiver shown in FIG.
, an intermediate frequency amplification circuit 13, and another set of detection circuits 14 are provided, and these detect the presence or absence of traffic information broadcasting. When traffic information broadcasting is detected, the selector switch 15 is switched to the detection circuit 14 side, and the traffic information broadcasting is transmitted to the speaker. It is to be played from 6 onwards.

[0008]

[Problems to be Solved by the Invention] However, although the radio receiver shown in FIG. 4 eliminates interruptions in the audio of the radio broadcast being received, it requires at least two sets of front ends, intermediate frequency amplification circuits, and detection circuits. However, there is a problem of high cost.

[0009]

[Means for Solving the Problems] The present invention solves such problems, and when a predetermined broadcast wave is detected, a radio receiver that receives the broadcast wave detects the broadcast wave being received. The method further comprises a level detecting means for detecting the level of the demodulated signal, and a control means for performing the predetermined broadcast wave detection operation when the level of the demodulated signal detected by the level detecting means is below a predetermined value. Features.

0010

[Operation] Since the predetermined broadcast wave detection operation is performed when the level of the demodulated signal of the broadcast wave being received is low, interruptions in the reproduced sound are less noticeable and the difficulty of hearing is alleviated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention, and the following description will be made with reference to this figure. Note that the same parts as in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

In the radio receiver of this embodiment, the detection circuit 4
A level detection circuit 8 that detects the detection output of the audio signal, that is, the level of the audio signal, and a comparison circuit 9 that compares the output signal of the level detection circuit 8 with a predetermined level and outputs the comparison result to the microcomputer 7 are provided. Note that the level detection circuit 8 includes, for example, a rectification circuit and a smoothing circuit that rectify and smooth the detected output of the detection circuit 4. Further, the comparison level of the comparator circuit 9 is given by a divided voltage obtained by dividing the power supply voltage by a fixed resistor R1 and a variable resistor VR1, and is adjusted by a variable resistor VR1. When the comparison circuit 9 determines that the level of the audio signal is below a predetermined value, the microcomputer 7 performs a traffic information broadcast detection operation.

Next, the operation of the microcomputer 7 will be explained as shown in FIG.
The operation will be explained according to a flowchart showing the operation.

[0014] When the power of the receiver is turned on, normal receiving operation, setting of the receiving frequency, changing of the receiving frequency according to the operation of the operation switch, changing of the receiving band, etc. are performed (step S1). In step S2, it is determined whether the mode is the traffic information receiving mode, and if it is the traffic information receiving mode, the process moves to step S3. This traffic information reception mode is set by the operator by operating a switch, and it can be determined whether the vehicle is in the traffic information reception mode or not based on the state of the switch.

In step S3, it is determined whether the level of the audio signal is below a predetermined value, and if it is below the predetermined value, the process moves to step S4, and if it is not below the predetermined value, the process moves to step S1. This determination can be made based on the output of the comparison circuit 9.

[0016] In step S4, a mute operation is performed. This is to prevent the generation of noise due to the reception frequency changing operation, and is performed by cutting off the signal path between the detection circuit 4 and the speaker 6, and is configured by a switching circuit using a transistor, for example.

[0017] In step S5, the reception frequency is set to 1620.
Set to KHz, that is, the traffic information broadcast frequency. Then, in step S6, it is determined whether traffic information is broadcast. This determination is made using the signal level signal described above. and,
If the traffic information broadcast is detected, the process moves to step S9, muting is canceled, and the traffic information broadcast is reproduced from the speaker 6.

[0018] Steps S10 and S11 are processes for detecting the cancellation operation of traffic information broadcasting, that is, the operation of traffic information by the operator, or the disappearance of traffic information broadcasting, and these states are detected. The operation of receiving traffic information is performed until the end. In addition, operations for canceling traffic information broadcasting include changing the receiving frequency, changing the receiving band (FM, A
M) changing operations, starting operations of other audio equipment such as a tape player, etc. Furthermore, detection of traffic information broadcasting is performed using the aforementioned signal level signal.

If it is detected that the traffic information broadcast is cancelled, or that the traffic information broadcast is no longer available, the process proceeds to step S1.
2, mute processing is performed and the process moves to step S7.

[0020] In step S7, the receiving frequency is changed to the receiving frequency before receiving the traffic information. Note that the reception frequency before traffic information reception may be stored in a memory before the traffic information detection operation (before step S5), and read from this memory in step S7. And step S8
to cancel the mute and return to step S1.

As described above, in this embodiment, the traffic information broadcast detection operation is performed when the audio signal level of the broadcast wave being received drops, so that the interruptions in the reproduced sound are less noticeable and the difficulty of hearing is reduced. suppressed. Note that the audio signal level decrease tends to continue for a certain period of time, such as between songs or conversations, so
It is very effective to perform the traffic information broadcast detection operation when the audio signal level of the broadcast wave being received drops as in this embodiment.

[0022] In this embodiment, 1620KHz
Although we have taken traffic information broadcasting as an example, it is possible to apply it to other traffic information broadcasts as well, and it can also be applied not only to traffic information broadcasts, but also to broadcasts of content specified from broadcast content data in radio data systems. ,It is valid.

[0023]

As described above in detail, according to the present invention, the detection operation of a predetermined broadcast wave is performed when the level of the demodulated signal of the broadcast wave being received is low, so that there is no interruption in the reproduced sound. It is unobtrusive and makes listening less difficult.

[Brief explanation of the drawing]

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

FIG. 2 is a flowchart showing the operation of the microcomputer 7.

FIG. 3 is a configuration diagram showing a conventional radio receiver.

FIG. 4 is a configuration diagram showing a conventional radio receiver.

[Explanation of symbols]

7. Microcomputer 8 Level detection circuit 9 Comparison circuit

Claims (1)

[Claims] 1. Level detection means for detecting the level of a demodulated signal of the broadcast wave being received in a radio receiver that receives the broadcast wave when a predetermined broadcast wave is detected; A radio receiver comprising: control means for detecting the predetermined broadcast wave when the level of the demodulated signal is below a predetermined value.