JPH11284529A - Radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform high speed operation of a scan function as restraining the malfunctions of a squelch by switching detecting speed of a noise squelch corresponding to a receiving state. SOLUTION: No scan signal is inputted in a controller 4 in a normal receiving state, and the controller 4 is controlled so that the capacitance of a variable capacitance capacitor VC is made large. In such a case, the malfunctions of opening and closing the squelch are reduced through the followup ability of output of a noise amplifier 2 in a noise squelch circuit 1 is deteriorated, and since the capacitance of the capacitor is large, the time constant becomes large as well. When the scan signal is inputted in the controller 4 at a special receiving state like scanning. etc., the controller 4 is controlled so that the capacitance of the variable capacitance capacitor VC is made to be small. At this time, high speed operation is enabled since the capacitance of the capacitor is made to be small, the time constant is also made to be small, and the rise of the output of the noise amplifier 2 in the noise squelch circuit 1 is speeded up, so that accelerated operation becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radio, and more particularly, to a radio having a detection circuit including a noise squelch circuit.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional example. In the figure, detection circuit 1
The noise squelch circuit 1 extracts only the noise component by a noise filter (not shown) based on the demodulated audio band signal, amplifies the extracted noise component by the noise amplifier 2, and the comparator 3 has a large or small amount of noise. Then, the input level of the received signal is determined, and the squelch opening and closing is controlled. As shown in FIG. 3B, the output itself of the noise amplifier always linearly follows the noise.
Depending on the level of the noise level, the squelch opening often occurs, causing a problem such as a break in conversation during use. Therefore, usually, a resistor, a capacitor, and the like are provided on the output side of the noise amplifier 2, and a time constant of the resistor and the capacitor is increased to average the noise level.
Squelch opening and closing is less likely to occur.

[0003]

If the time constants of the resistor and the capacitor are increased, noise levels can be averaged, so that malfunctions in squelch opening and closing can be prevented. However, since the time constant is large, noise is reduced. Follow-up performance is reduced. For this reason, there is a problem that the signal rising and falling speed of the noise squelch circuit becomes slow, and as a result, the scanning operation also becomes slow.

[0004]

According to the present invention, in order to solve the above-mentioned problems, the present invention is adapted to use conditions during normal reception and during special reception such as two-wave simultaneous reception, memory scan and scan state. And control means for switching and controlling the time constants of the resistor and the capacitor. As a result, in the normal reception state, the squelch operation is stable in the same manner as described above. Therefore, the time constant is increased, and the responsiveness to noise is slowed, so that the squelch malfunction hardly occurs. On the other hand, in special reception conditions such as scanning, the time constant is reduced,
High-speed operation is possible by increasing the follow-up to noise.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In a normal reception state, no scan signal is input to the controller 4, and the controller 4 controls the variable capacitor VC so that the capacitance thereof is large. At this time, as shown in FIG. 1A, since the capacitance of the capacitor is large, the time constant also becomes large, and the output of the noise amplifier 2 in the noise squelch circuit 1 has poor followability as shown in FIG. However, malfunction of squelch opening and closing is reduced.

On the other hand, in a special reception state such as scanning, a scanning signal is inputted to the controller 4. When the scan signal is input, the controller 4 controls the capacity of the variable capacitor VC to be small. At this time, since the capacitance of the capacitor is reduced as shown in FIG. 1B, the time constant is also reduced, and the output of the noise amplifier 2 in the noise squelch circuit 1 rises faster as shown in FIG. 3B. , High-speed operation becomes possible.

[0007]

According to the present invention, by switching the noise squelch detection speed according to the reception state, it is possible to suppress the malfunction of the squelch and to perform the high-speed operation of the scanning function.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration example of a conventional squelch circuit.

FIG. 3 is a diagram showing output characteristics of a noise amplifier.

[Explanation of symbols]

1, 11: detection circuit, 2: noise amplifier, 3: comparator, 4: control circuit.

Claims (1)

[Claims] In a wireless device having a detection circuit including a noise squelch circuit, a malfunction is less likely to occur during use by stabilizing a squelch operation by delaying a rise of a squelch detection voltage in a normal state, and a squelch detection voltage is reduced in a scan. A wireless device comprising a control means for performing switching control so that a high-speed scan can be performed by increasing a rising speed.