JPH03162012A - Transmission equipment - Google Patents

Abstract

PURPOSE:To eliminate mutual modulation wave to prevent voice lock by providing a high pass filter to the post stage of a clipper circuit. CONSTITUTION:A high pass filter 14 is provided to the post stage of a clipper circuit 13. When a voice signal with large level is inputted from a microphone 11 and its intermodulation wave is generated at a tone frequency band, a high pass filter 14 cuts off an undesired tone frequency band. Thus, when the voice signal from the high pass filter 14 and the tone signal from a tone circuit 15 are synthesized, the undesired component of the band of a squelch tone signal is eliminated and the resulting signal is sent. Thus, the voice lock is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transmitter that performs squelch using a tone signal.

Conventional technology FIG. 2 shows the configuration of a conventional transmitting device.

In Fig. 2, the low frequency components of the audio signal from the microphone (MIC) 1 are passed through the high pass filter (HPF) 2.
The audio signal whose low frequency components have been cut is synthesized with the squelch tone signal from the tone circuit (TONE) 4, and the maximum amplitude of the synthesized signal is limited by the clipper circuit (CLIP) 5.

The high frequency band of the output signal of the clipper circuit 5 is cut by a low pass filter (LPF), and the output signal is sent to the transmitter (T
The signal is modulated by X)7 and transmitted wirelessly.

Problems to be Solved by the Invention However, in the conventional transmitting device described above, when a high-level voice band signal is manually input, an intermodulation wave thereof is generated in the tone frequency band in the clipper circuit 5, so that the tone is beat or suppressed. , there is a problem that voice lock occurs.

The present invention solves the above conventional problems, and aims to provide a transmitting device that can prevent voice lock.

Means for Solving the Problems In order to achieve the above object, the present invention provides a high-pass filter at the subsequent stage of the clipper circuit.

According to the above structure, when a high-level voice band signal is input and its intermodulation wave is generated in the tone frequency band in the clipper circuit, the present invention is removed by the /X pass filter, thus preventing voice lock. be able to.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing an example of a transmitting device according to the present invention.

In FIG. 1, 11 is a microphone (MIC) that converts audio into an electrical signal, 12 is a pre-emphasis circuit (PRE EN) that emphasizes the high frequency band of the signal from the microphone 11, and 13 is a pre-emphasis circuit (PRE EN) that enhances the high frequency band of the signal from the microphone 11. A clipper circuit (CLIP) limits the maximum amplitude of the audio signal from the circuit 12, and 14 is a high-pass filter (HPF) that cuts the low frequency component of the audio signal whose maximum amplitude is limited by the clipper circuit 13. .

IS is a tone circuit (TONE) that generates a squelch tone signal; 16 is a low-pass filter (TONE) that cuts high frequency components of a composite signal of the audio signal from the high-pass filter 14 and the tone signal from the tone circuit 15; LPF
), 17 is a transmitter (TX) that modulates the output signal of the low-pass filter 16 and transmits it wirelessly.

Next, the operation of the above embodiment will be explained.

In FIG. 1, when a high-level audio signal is input from the microphone 11 and its intermodulation wave is generated in the tone frequency band in the clipper circuit 13, the high-pass filter 14 cuts off the unnecessary tone frequency band.

Therefore, when the voice signal from the high-pass filter 14 and the tone signal from the tone circuit 15 are combined, unnecessary components in the band of the squelch tone signal are removed and transmitted, thereby preventing voice lock.

Effects of the Invention As explained above, in the present invention, a high-pass filter is provided after the clipper circuit, so that when a high-level audio band signal is input and the intermodulation wave is generated in the tone frequency band in the clipper circuit, , are removed by a high-pass filter, thus preventing voice lock.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a transmitting device according to the present invention, and FIG. 2 is a block diagram showing a conventional transmitting device. 11... Microphone (MIC), 13... Clipper time 1 (CLIP), 14... High pass filter (H
PF), l5...Tone circuit (TONE), 16...
・Low pass filter (LPF), 17...Transmitter (T
X).

Claims (1)

[Claims] A clipper circuit that limits the maximum amplitude of an audio signal, a high-pass filter that cuts low frequency components of the output signal of the clipper circuit, and a composite signal of the output signal of the high-pass filter and a squelch tone signal. A transmitter comprising: a low-pass filter that cuts high-frequency components of the low-pass filter; and a transmitter that wirelessly transmits an output signal of the low-pass filter.