JPS5989029A - Receiver with automatic channel selecting function - Google Patents

Abstract

PURPOSE:To receive only a station having a good receiving state by controlling a channel selecting operation in response to the noise component contained in a received signal. CONSTITUTION:A PLL circuit 7 performs a channel selecting operation and applies the local oscillation outputs successively to a tuner 2. When the signal received by the tuner 2 exceeds a certain field level, an instruction is given to a controller circuit 8 from a stop signal generator 10 to stop the sweep of frequency. An intermediate frequency signal is sent to an impulsive noise eliminating circuit 13. When the output signal sent from an HPF12 within the circuit 13 is large, it is decided that an audio signal contains a big distortion. In this case, the sweep stop of frequency is released and then the frequency sweep is started again.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiver with an automatic tuning function, and more particularly to a receiver with an automatic tuning function that is improved so as to receive and select only stations with good reception quality.

A conventional receiver with an automatic channel selection function has a configuration block diagram shown in FIG.

The configuration and operation of a conventional receiver will be explained with reference to FIG. A tuner 2 selects a predetermined reception frequency for the radio waves received by the antenna 1.

The tuner 2 generally includes a high-frequency amplification circuit, a frequency conversion circuit, and a local oscillation circuit, and the high-frequency amplification circuit and the local oscillation circuit are composed of tuning varicap diodes.

At this time, when the automatic channel selection switch 9 is pressed, the controller circuit 8 operates and sends a control signal including a reference signal to the PLL circuit 7. Accordingly, PLL times N7
is IIJ for the tuning varicap diode of tuner 2.
The control voltage operates to select a specific receiving frequency from among the received radio waves received by the antenna 1.

The reception frequency selected by the tuner 2 is detected and amplified in an intermediate frequency amplification circuit 3 having a built-in detection stage. Then, the stop signal generation circuit 1o connected to the intermediate frequency amplification circuit 3 generates a DC voltage according to the received electric field level of the received radio wave, and when this DC voltage exceeds a predetermined value, the stop signal generation circuit 10 is activated by the controller. Controller 8 controls circuit 8! Send Il stop signal. As a result, the controller circuit 8 stops the operation of the PLL circuit 7, and the tuner 2 selects and locks a specific receiving frequency.

In addition, the wave is detected by the intermediate frequency amplification circuit 3 with a built-in detection stage, and j
The l1-width signal is input to the next muting circuit. At this time, in response to the locking of the tuner from the controller circuit 8, the muting circuit 4 has a
Receives muting stop signal. Therefore, the signal is not muted in the muting circuit 'Is4, and the signal is transferred to the next low frequency amplification circuit. Then, the signal whose low frequency component is amplified by the low frequency amplifier circuit is outputted as an audio signal by the speaker 6.

By the way, such a conventional receiver with an automatic tuning function detects and amplifies only the electric field level of the received radio wave, in other words, the received signal selected by the tuner, and when the output is above a predetermined level. In all cases, the operation of the controller circuit 8 was stopped and automatic tuning was locked to the selected frequency. Therefore, for example, the received signal may be affected by multipath interference, intermodulation, or disturbances! 1. When a noise component such as interference is included, in other words, a received signal that looks like so-called distortion/ν noise is being received. There was a drawback that it could be stored away.

Therefore, an object of the present invention has been made to solve the above-mentioned drawbacks, and to provide an automatic 31I station function reception 1i11J that is adapted to receive a good reception signal lj with less noise components. That's true.

Another object of the present invention was to take note of the fact that many recent receivers are equipped with so-called impulsive noise elimination circuits that eliminate VJJ impulsive noise generated, for example, by the ignition system of automobiles. An object of the present invention is to provide a receiver with a self-fiO selection 8 function, which uses a bypass filter included in the impulsive noise removal circuit to automatically select a frequency at which a good received signal can be obtained. .

Simply put, this invention detects that the received signal contains a predetermined value or more of high-frequency noise components even if the received signal selected by the automatic tuning circuit is at a predetermined level or higher. This receiver has an automatic tuning function and is equipped with a circuit that prevents the received signal from tuning.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 2 is a circuit configuration block diagram of a preferred embodiment of the present invention. The configuration and operation of this embodiment will be explained below with reference to FIG.

First, in the configuration, the intermediate frequency amplifier circuit 3 with a built-in detection stage
An impulsive M sound removal circuit 13 is interposed between the muting circuit 4 and the muting circuit 4 . The output of this impulsive noise removal circuit 13 is sent to the controller circuit 8 via the amplification and rectification circuit 14. This is one of the features of this embodiment.

The impulsive noise removal circuit 13 includes a 117 impulsive noise removal circuit main body 11 and a bypass filter 12. The impulsive noise removal circuit 13 receives an audio signal input from the intermediate frequency amplification circuit 3 with a built-in detection stage, and extracts from the components of the signal,
Bypass filter 12 detects the presence or absence of high frequency components. piti detected by bypass filter 12
The 14 components are input to the impulsive noise removal circuit main body 11, and are also sent to the amplification and rectification circuit 14 connected to the next stage.
There, it is amplified, converted into a DC component, and sent to the controller circuit 8.

If the audio signal input from the intermediate frequency amplification circuit 3 with a built-in detection stage to the impulsive noise removal circuit 13 is affected by -2. ?
If there are at least seven types of interference, the signal will contain many high-frequency components, so the bypass filters 6 and 12 will detect the high-frequency components, and the amplification and rectification circuit 14 will output the DC signal. It will be output. Zoshimata,
With this DC signal output, the next circuit operation
As shown in FIG.

In the circuit block of J3 and F1' receiver shown in FIG. 2, the same or corresponding parts as in the FT example of FIG.

Next, the actual Dl in Figure 2! Let's explain the operation of the example.

When the automatic tuning switch 9 is turned on, the controller circuit 8 operates and sends the ff and II M signals to the PLI circuit 7, and the PLL circuit accordingly switches between the varicap diodes for tuning of channels 1 and 2. A control OII voltage is applied to the tuner 2 to cause the tuner 2 to select a specific reception frequency. A reception frequency of a specific electric field level selected by the tuner 2 is detected and amplified by an intermediate frequency Jn width circuit 3 having a built-in detection stage.

When the output of this circuit 183 is equal to or higher than a predetermined level, a stop signal is sent from the stop signal generating circuit 10 to the controller circuit 8.

On the other hand, the output of the intermediate frequency amplification circuit 3 with a built-in detection stage is sent to the one-shot noise removal circuit 13. Then, in the bypass filter 12 of this noise removal circuit 13, the output signal of the intermediate frequency amplification circuit 3 contains a high frequency component, that is, the intermediate frequency amplification circuit l.
It is detected whether or not the output audio r71 signal of '&3 is distorted and contains a high frequency component. If a high frequency component is included, it is detected by the bypass filter 12 and output to the amplification and rectification circuit 14. In the amplification and rectification circuit 14, a DC component is created from the high 3N component signal detected by the bypass filter 12. If this DC component is equal to or greater than a predetermined value W1, an output is given to the controller circuit 8 that invalidates the stop signal output of the stop signal generating circuit 10. In other words, even if a stop signal is output from the stop signal generation circuit 10 to the controller circuit 8, if there is an output from the amplification and rectification circuit 14 to the controller circuit 8; in this case, this stop signal stops the control of the controller circuit-8. It is not possible to do so.

When two signals are input to the controller circuit 8, giving the output signal of the amplification and rectification circuit 14 to the controller circuit 8 preferentially over the stop signal from the stop signal generation circuit 10 can be specifically performed, for example. You can do it like this: That is, by using an AND gate, the stop signal from the stop signal generation circuit 10 (the i bow is input directly to one input terminal of the AND gate, and the output signal of the amplifying circuit 14 is input to the other input terminal of the AND gate via an inverter). The controller circuit 8 may be operated by the output signal of the AND gate.Alternatively,
More generally, this can also be accomplished by a predetermined program used to control the controller I/roller circuit 8.

As described above, the control of the controller 1-roller circuit 8 is not stopped by the stop signal from the stop signal generation circuit 10,
Furthermore, control of the PLL circuit 7 is continued.

The tuner 2 linked to the PLL circuit 7 operates to sequentially tune to the next received frequency. and the tuned reception frequency is above a predetermined electric field level,
When no high-frequency components are included, the control of the controller circuit 8 is stopped and the tuner 2 is fixed at the receiving frequency.

The impulsive noise removal circuit 13 used in this embodiment is generally included in most recent receivers in order to remove impulsive noise generated by, for example, an automobile's ignition system. This embodiment utilizes the high frequency component output extracted from the bypass filter 12 provided in the impulsive noise removal circuit. Thereby, the receiver circuit 4fl 7ifl' can be achieved at lower cost and in a smaller space.

4. In the above case, instead of using the bypass filter 12 of the impulsive noise removal circuit 13, the output of the intermediate frequency amplification circuit 3 with a built-in detection stage is sent to the amplification and rectification circuit 14 via another bypass filter. Of course, you can also do tMIfc.

As described above, according to the present invention, the received signal tuned to C by the automatic tuning circuit is at a predetermined level or higher (
The system is also equipped with a circuit that detects when a received signal contains high-frequency noise components exceeding a predetermined value and prevents the received signal from being tuned, making it possible to tune in to a received signal with good sound quality. It is possible to provide an optical system with an automatic channel selection function (i-device).

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional receiver with an automatic channel selection function. FIG. 2 is a block diagram C of an embodiment of the present invention. In the figure, 2 is a duplex, 3 is an intermediate frequency amplifier circuit with a built-in detection stage, 7 is a PLL circuit, 8 is a controller circuit, 1
0 is a stop signal generation circuit, 11 is an impulsive noise removal circuit main body, 12 is a bypass filter, 13 is an impulsive noise removal circuit, and 14 is an amplification and rectification circuit.

Claims (4)

[Claims] (1) A receiver capable of automatically tuning broadcast radio waves, which is provided in connection with a tuner, and includes an automatic tuning circuit for automatic tuning, and detecting a received signal tuned by the automatic tuning circuit. a circuit for amplifying, a circuit for generating a stop signal to the automatic tuning circuit when the output of the detection amplification circuit is equal to or higher than a predetermined level, and a circuit for extracting a high frequency component from the output of the detection amplification circuit; A receiver equipped with automatic channel selection 11, including a circuit that controls the stop signal from the stop signal generation circuit according to the component output. (2) The receiver with an automatic tuning function according to claim m'r, wherein the control circuit includes a bypass filter that detects at least high-frequency components and a rectifier that rectifies the output thereof. (3) The receiver further includes an impulsive noise removal circuit connected to the output of the detection amplification circuit, and the impulsive noise removal circuit is provided with a bypass filter that receives the output of the detection amplification circuit, and the bypass filter 3. The receiver with an automatic channel selection function according to claim 2, wherein the filter also serves as a bypass filter for detecting the high frequency component. (4) The control circuit is configured to invalidate the output of the stop signal generation circuit when the high-frequency component output is equal to or higher than a predetermined value based on its output. Receiver with automatic channel selection function as described in section.