JPS6228616B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a PLL synthesizer type radio receiver equipped with a channel switch (hereinafter simply referred to as CH switch) using a touch key to call up a pre-stored frequency. It is an object of the present invention to provide a radio receiver that can give a user recognition of the operation by emitting a sound when operating the CH switch.

Generally, in a PLL synthesizer type radio receiver, in order to generate sound when the CH switch is operated, as shown in Figure 1, the frequency signal from oscillator 1, which also serves as the reference oscillator for the PLL, is sent to frequency divider 2. The gate 3 is opened to apply the audio frequency signal to the low frequency amplifier 5 only when the CH switch 4 is operated, and the audio frequency signal is generated from the speaker 6. However, in the above case, there was a problem in that the use of the frequency divider 2 and the gate 3 increased the cost.

The present invention eliminates such conventional drawbacks, and the present invention will be described below with reference to drawings of embodiments.

FIG. 2 shows an embodiment of the present invention. In the figure, 11 is a plurality of CH switch groups, and 12 is a group of CH switches.
A code generator outputs a predetermined channel code by operating the CH switch 11; 13 is a synthesizer circuit that is swept by the channel code from the code generator 12; 14 is a lock detector terminal L constituting the synthesizer circuit 13. A waveform conversion circuit connected to _D , 15 a muting circuit operated by the output of the waveform conversion circuit 14, 16 a low frequency amplifier circuit muted by the muting circuit 15, 1
7 is a speaker driven by the low frequency amplifier circuit 15, and 18 is a buffer amplifier for amplifying the audible frequency reference signal taken out from the lock detector terminal L _D of the synthesizer circuit 13 via the capacitor _C1 . , the output of this buffer amplifier 18 is attenuated by resistors R ₁ and R ₂ and connected to the low frequency amplifier circuit 16 via a coupling capacitor C ₂ .
It is now being added to

Here, the synthesizer circuit 13 is usually a PLL.
It is an IC version of circuits such as a phase comparator and a programmable divisor, and a PLL is connected to the lock detector terminal L _D as shown in Figure 3A.
Outputs a signal to determine whether it is in LOCK (steady) state or UNLOCK (transient response) state. That is, in FIG. 3A, sections A and C are in a steady state, and section B is in a transient response state, in which a reference signal (phase comparison frequency) of an audible frequency is output. Further, the low frequency amplifying circuit 16 is normally applied with a detection signal from a radio receiving circuit (not shown), and a muting circuit 15 provided at this stage is used.
is designed to prevent abnormal noise from being output to the speaker 17 during a transient response. The reference signal taken out from the buffer amplifier 18 is applied to the low frequency amplifier circuit 16 at the rear end of the muting stage.

In a radio receiver having such a configuration, when one of the plurality of CH switches 11 is operated, a channel code corresponding to the operated CH switch 11 is applied from the code generator 12 to the synthesizer circuit 13, The synthesizer circuit 13 starts sweeping. At this time, the synthesizer circuit 13 is in a transient response state, and an audible frequency reference signal as shown in the section B of FIG. 3A is output to its lock detector terminal L _D. Then, only the alternating current component of this reference signal is taken out by the capacitor C ₁ to the buffer amplifier 18, and the level is lowered by the resistors R ₁ and R ₂ , and then sent to the low frequency amplifier circuit 16 via the coupling capacitor C ₂ .
added to. Therefore, the speaker 17 reports the sound corresponding to the operation of the CH switch 11, thereby making it possible for the user to recognize the operation of the CH switch 11. After such an operation, when the synthesizer circuit 13 is set to the pre-stored frequency, the reference signal is no longer output to the lock detector terminal L _D , and the sound generation corresponding to the reference signal from the speaker 17 is stopped. , signals corresponding to the receiving frequency will be reported. On the other hand, the discrimination signal outputted to the lock detector terminal L _D when the CH switch is operated is converted by the waveform conversion circuit 14 into a signal as shown in FIG. 3B, and the muting circuit 15 is operated. At this time, the mutating circuit 15 operates only in the output section of the reference signal and mutates the area before the input stage of the reference signal of the low frequency amplifier circuit 16.
Abnormal noise during transient response can be effectively removed and does not affect the reference signal. Since the reference signal is attenuated by the resistors R ₁ and R ₂ , it is applied to the low frequency amplifier circuit 16 at a small level, and although it is originally not suitable for listening to a loud sound, it can withstand practical use. The intensity does not need to be very strong in order to actively use the reference signal.

Note that the reference frequency is usually the FM band.
Different depending on AM band (25kHz for FM, 25kHz for AM)
1kHz), but this frequency difference is also effective for distinguishing between FM and AM operations, and is also useful for digital tuning synthesizers that set the reception frequency using pulses generated by rotating the tuning knob. When applied to a receiver, the user can be made aware of the operation by sounding based on the reference frequency at the instant the pulse is generated.

As described above, according to the present invention, there is no need for a special circuit to utilize an audible frequency reference signal, the operation recognition of a CH switch can be provided with a simple circuit configuration, and This has the advantage of reducing the need for mutating measures to prevent abnormal noise.

[Brief explanation of the drawing]

FIG. 1 is a circuit connection diagram of a conventional radio receiver, FIG. 2 is a circuit connection diagram showing an embodiment of the radio receiver of the present invention, and FIG. 3 is a waveform diagram of its essential parts. 11... CH switch, 12... Code generator, 13... Synthesizer circuit, 14... Waveform conversion circuit, 15... Muting circuit, 16...
Low frequency amplifier circuit, 17... speaker, 18... buffer amplifier.

Claims (1)

[Claims] 1. Extract the audible frequency reference signal of the PLL circuit that is generated during the tuning operation, and add this reference signal to the low frequency amplification circuit after the muting circuit to prevent abnormal noise during the transient response of the above PLL circuit to recognize the operation. A radio receiver characterized in that it is configured to report the pronunciation to be given.