JPS6148238A - Squelch device - Google Patents

Abstract

PURPOSE:To attain output of voice even within a prescribed range of a reception input during digital squelch operation by providing a comparator circuit among a squelch voltage varied by a potentiometer, a noise voltage and a digital squelch operating voltage. CONSTITUTION:A radio signal having a digitized voice is extracted by a receiver 2, demodulated by a demodulation circuit 3 to transmit a digital signal (a) and a synchronizing signal (b). The signals a, b are inputted to a decoding circuit 4 and a digital squelch circuit 10, which gives a l level output when the signal is coincident with a prescribed digital signal system and gives a 0 level output when dissident. A noiselevel of the signal (a) subject to detection 8 through an HPF7 is inputted to a comparator 11 of a noise controller 9. The controller 11 uses resistors 15, 16 12 and a squelch variable resistor 13 to set a voltage corresponding to a criterion input voltage of the circuit 10 and a voltage Vse within the noise squelch range, and they are fed respectively to comparators 14, 11. In setting them as Vse>V0, the controller 9 connects/disconnects the amplifier 5 depending on the discrimination of the circuit 10 and the comparator 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a squelch device used in a digital modulation mobile radio receiver or the like.

2. Conventional configuration and its problems Traditionally, digital modulation mobile radio receivers have a noise squelch circuit that detects the noise component of the demodulated signal and connects or disconnects audio output, and a noise squelch circuit that connects or disconnects the audio output by detecting the noise component of the demodulated signal. It has a built-in digital squelch circuit that detects whether the signal format is selected and connects or disconnects the audio output. and,
This digital squelch circuit prevented decoding of interference waves.

However, in this conventional example, as shown in Figure 1, the reception input voltage level of the radio that enables the dental squelch is higher than the reception input voltage level of the radio that enables the noise squelch. Human power QdB
If the μV suddenly drops to -4 dBμV during a call, the digital squelch circuit will operate and the audio output will be cut off, even though it is actually within the audible range.

OBJECTS OF THE INVENTION The present invention eliminates the problems of the prior art as described in (-).Even if the receiving input is operated by a digital squelch circuit, when the noise is within the squelch range, the sound volume is reduced to 3. The purpose is to present an excellent noise control device that can be connected.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention connects or disconnects an amplifier based only on the judgment of the noise squelch circuit when the squelch volume setting is below the judgment limit of the digital squelch. When the squelch judgment limit is exceeded, the amplifier is connected or disconnected based on both the noise squelch circuit judgment and the digital squelch circuit judgment, and even if the receiving input is the one where the digital squelch circuit operates , it has the advantage that the audio output is connected when it is within the noise squelch range.

DESCRIPTION OF EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a digital radio receiving device including a noise control device according to an embodiment of the present invention.

In FIG. 2, 1 is an antenna, 2 is a receiver that extracts a desired radio frequency, and 3 is a demodulation circuit that outputs a digital demodulation signal a and a synchronization signal l].

4 is a decoding circuit that inputs the digital demodulated signal a and the synchronization signal S and outputs an analog decoded signal C; 5 is a decoded signal C
An amplifier inputs and amplifies the signal, and 6 is an output terminal. This amplifier 5 connects the output to the output terminal 6 by the control signal d,
It is something that can be cut off. 7 is a high-pass filter that inputs the demodulated signal a and extracts only high-frequency components; 8 is a detection circuit that detects the output of the high-pass filter 7; 9 is a noise control device of this embodiment;
Reference numeral 10 denotes a digital squelch circuit which inputs the demodulated signal a and the synchronizing signal S and determines whether the signal format is a predetermined one. This digital squelch circuit 10 starts determining whether or not a predetermined signal format is used when the receiving input of the antenna 1 is 13 dBμ or more as shown in FIG. 1, depending on the amount of noise components contained in the demodulated signal. 11 is a comparison circuit which inputs the signal of the detection circuit 8 and compares it with the voltage of VsQ; 12.
Reference numeral 13 denotes a resistor connected in series between the power source and the ground, and the resistance value of the resistor 13 is variable. A comparator 14 compares the voltage of V8Q with the voltage of vo, which is created by the voltage divided by the five-vane resistor 15 and resistor 16. 17 is an active low OR circuit that inputs the signals of the comparator 14 and the digital squelch circuit 10; 18 is an active low AND circuit that inputs the signal of the OR circuit 17 and the signal of the comparator 11; 18 is the output terminal 6 of the amplifier 5.
It controls connection and disconnection to

Next, the operation of the above embodiment will be explained. In FIG. 2, when a radio signal containing digitized audio arrives at antenna 1, receiver 2 extracts only the desired radio frequency.
The demodulation circuit 3 demodulates the signal. The demodulation circuit 3 sends out a digital demodulation signal a and a synchronization signal S created using predetermined logic.

The digital squelch circuit 10 determines whether the demodulated signal a and the synchronization signal are a predetermined digital signal system, and outputs "1" if they match, and "0" if they do not match. On the other hand, a high-frequency component of the demodulated signal a is extracted by a high-pass filter 7 and detected by a detection circuit 8. The output voltage of the detection circuit 8 increases as the number of high-frequency components increases, that is, as the input voltage of the weaker electric field increases.

The noise control device 9 is set to V. is set to the voltage of the detection circuit 9 corresponding to the judgment limit input voltage (-3 dBμV) of the digital squelch circuit 10. Also, the voltage value of ■8Q is determined by the resistance value of the variable resistor (squelch volume) 13, and the noise squelch range in Figure 1 is -1QdBμ■
~]QdBμV is set so that the voltage change of the detection circuit 9 corresponds to up to QdBμV.

(1) When Vo > V6Q, that is, the squelch volume 13 is smaller than the judgment limit of the digital squelch circuit 100 (]QdBμV~-3d
BμV), the output of the comparator 14 is always “
0", and the output of the OR circuit 17 is also always "0".

That is, the OR circuit 17 becomes unrelated to the output of the digital squelch circuit 10.

Here, when the received input voltage is higher than VsQ and therefore the output voltage of the detection circuit 8 is higher than VSO, the comparator 11
The output of the amplifier 5 becomes "1", and the output of the A, ND circuit 18 is also "1" and the output voltage of the amplifier 5 is cut off.

7'\-7 Also, when the received input voltage is smaller than vlIQ and therefore the output voltage of the detection circuit 8 is smaller than VBQ, the output of the comparator 11 becomes "0", and the output of the A, N D circuit 18 becomes "0", making the output voltage of the amplifier 5 a contact.

In this way, if the squelch volume voltage (vSQ) is made smaller than the digital squelch setting voltage, it will be unrelated to the judgment of the digital squelch circuit, and if only the noise squelch is judged, the output of the amplifier 5 will be connected. Cut off.

(2) When Vo > VSQ, that is, the squelch volume 13 is thicker than the judgment limit of the digital squelch circuit ('(-3dBμV~QdBμ
V) If set, the output of comparator 14 will always be Ill
The output of the OR circuit 17 is the output of the digital squelch circuit 1.
It depends on the output of 0. If the specified digital signal system is used, the digital squelch circuit 10 is "1", so
The output of the OR circuit 17 also becomes "1", and if the predetermined digital signal system is not used, the digital squelch circuit 10 will
Since it is OJ, the output of the OR circuit 17 is also "0".

Here, when the received input voltage is larger than vSQ and therefore the output voltage of the detection circuit 8 is larger than VsQ, the comparator 1
The output of 1 becomes "]", and the output of the AND circuit 8, which is related to the output of the OR circuit 17, becomes "1", and the output voltage of the amplifier 5 is turned off.

When the receiving input voltage is still smaller than v, Q, and therefore the output voltage of the detection circuit 8 is smaller than ■, Q, the comparator 11
The output of becomes [0-1. A, 11 of ND circuit 18
-1 is influenced by the output of the OR1 circuit 17. When the output of the digital squelch circuit 10 is "0", the output voltage of the amplifier 5 is connected, and the output of the digital squelch circuit 10 is "0".
1, the output voltage of the amplifier 5 is cut off.

In this way, if the squelch volume voltage (V, Q) is set higher than the digital squelch setting voltage, the output of the amplifier 5 will be connected when both the digital squelch circuit judgment and the noise squelch judgment are good. becomes.

Effects of the Invention 9 ・, -7 As is clear from the above embodiments, the present invention has the following advantages: (1) When the setting of the luciphon IJ, - is below the digital squelch noise judgment limit, only the noise squelch circuit can be used for judgment. Connect/disconnect the amplifier and squelchivo IJ.

- When the system setting exceeds the digital squelch judgment limit, the amplifier is connected or disconnected based on both the noise squelch circuit judgment and the digital squelch circuit judgment, so the digital squelch circuit operates. This has the effect that even if the reception input is within the noise squelch range, the audio output is connected.

[Brief explanation of the drawing]

Demodulation circuit, 5... Amplifier, 7... High-pass filter, 8
...Detection circuit, 9.Noise control device, 10.Digital squelch circuit, 11.Comparator, 12, 15.16.Resistor, 13.Squelch volume, 14.Comparator,
17-OR circuit, 18-AAND circuit.

Claims (1)

[Claims] a first comparator that compares the magnitude of a squelch voltage whose voltage is varied by a squelch volume and a noise voltage whose output voltage changes depending on the amount of noise; and the squelch voltage whose voltage is varied by the squelch volume and a predetermined voltage. an OR circuit that inputs the output of the second comparator and the output of a digital squelch circuit that determines whether the demodulated signal is in a predetermined digital signal format; A squelch device comprising an AND circuit inputting the output of the OR circuit and the output of the first comparator, the output of the AND circuit connecting or disconnecting the output of the amplifier.