JPH06303162A - Squelch signal generator and squelch controller - Google Patents

Abstract

PURPOSE:To provide a squelch signal generator and a squelch controller in which simple individual calling is attained with a few externally mounted components by effiectively utilizing an existing CPU function. CONSTITUTION:A frequency from a waveform generating circuit 13 is given to an input of a low pass filter 4 together with a signal from an audio amplifier circuit 3. The circuit 13 is connected to an output port P1 of a beep signal of a CPU 15 and is a filter circuit converting a rectangular or triangle wave form beep tone (e.g. 2928Hz) generated from the CPU 15 into a sine wave signal of the same frequency. The method is used because the transmission of undesired higher harmonics is prevented by shaping the deep tone into a sine wave. Through the constitution above, the CPU 15 controls the frequency port P1 in terms of softwave, then it is possible to send the sine wave of the same frequency as the deep signal while being superimposed on the voice signal from a microphone 1. Thus, the function of the existing CPU 15 is utilized effectively and the squelch signal generator capable of attaining simple individual calling is obtained with a few externally mounted components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squelch signal generator and a squelch control device which enable simple individual calling in a radiotelephone device.

[0002]

2. Description of the Related Art In recent years, wireless telephone devices using weak radio waves have been approved by the Ministry of Posts and Telecommunications. This is a so-called specified low power transceiver. This transceiver does not require a license and can be used by anyone, and many small, lightweight, and inexpensive products are on the market, and they are rapidly becoming popular, especially among young people.

However, since this transceiver has a small number of allocated channels, the line becomes congested due to the spread of the product, especially in a place with good visibility such as a ski resort, and interference has become conspicuous.

In order to prevent such interference, a device having a CTCSS (tone squelch) system has been commercially available. A transceiver on the transmission side equipped with this method always superimposes a tone signal of a specific frequency on a call voice signal from a microphone for transmission. On the other hand, the transceiver on the receiving side separates and detects the tone signal from the voice signal, releases squelch only when the tone signal matches a predetermined set frequency, and outputs the received voice to the speaker.
Therefore, if the frequency of the tone signal is previously set to be the same between transceivers equipped with this method, voice output is performed only when a radio signal from a specific partner is received, and the voice transmitted by a third party is bothered. Will disappear.

[0005]

However, the above-mentioned CT
In the CSS method, a circuit for generating a tone signal of a set frequency or a circuit for superimposing this on a call voice is required in the transmitting unit, and a circuit for separating and detecting the tone signal from the voice signal in the receiving unit or this circuit is required. It is necessary to have a circuit for comparing Although such a circuit is formed as an IC, it is likely to be a large package due to its complicated function and is expensive. Therefore, in particular, the specific low power transceiver, which is sold in terms of downsizing and price reduction, has been a big problem in terms of mounting space and cost.

The present invention has been made in view of the above problems, and a squelch signal that enables simple individual calling with a few external parts by effectively utilizing the functions of an existing microcomputer (CPU). It is an object to provide a generator and a squelch controller.

[0007]

In order to achieve the above object, the squelch signal generator of the present invention intermittently generates a Beep signal only during a predetermined time immediately after the start of transmission.
p signal generating means, waveform shaping means for shaping the beep signal into a sine wave signal, and transmitting means for transmitting the sine wave signal by superimposing on the voice signal from the microphone or by switching to the voice signal. And

Then, in the device for receiving this,
A tone decoder that detects a Beep signal in a received signal, a detection unit that detects that the detection output of the tone decoder is continuous two or more times at a predetermined pulse interval, and a squelch control that cancels squelch according to a command from the detection unit. And a squelch control device including means.

[0009]

In the squelch signal generator of the present invention having the above-described structure, the Beep signal generating function of the control CPU is controlled so that the beep is intermittent only during a predetermined time immediately after the start of transmission.
Generate a signal. The intermittent deep signal is generated at a predetermined pulse interval and duty ratio. CPU
The Beep signal generated by is generally rectangular wave-shaped or triangular wave-shaped and contains a lot of harmonic components, so this is removed to form a sine wave signal. This sine wave signal is superimposed on the audio signal from the microphone and transmitted as a squelch signal for canceling the squelch of the other receiver. In this case, the audio signal of the microphone and the squelch signal may be selectively switched and connected to the transmission circuit for transmission.

On the other hand, in the device for receiving this, the squelch is normally closed and the received voice is not output, but the tone decoder and the detection means cause the Beep signal in the received signal to be 2 at a predetermined pulse interval. If it is detected that the squelch control has been repeated more than once, the squelch control means releases (opens) the squelch and starts the output of the received voice.

Therefore, the intermittent Beep signal having the predetermined pulse interval and duty ratio acts as a key for opening the lock, and the squelch of the receiver opens (releases) only when the radio wave of the specific partner is received. ) It will be.

[0012]

Embodiments of the squelch signal generator and the squelch controller according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a radio telephone device incorporating a squelch signal generator and a squelch controller according to the present invention. As shown in the figure, this device amplifies / modulates the call voice from the microphone 1 and transmits it from the antenna 8 (reference numerals 1 to 7), and amplifies the radio wave received from the antenna 8.
It is configured by a receiving unit (reference numerals 9 to 12) that demodulates and outputs sound from the speaker 12.

First, the transmitting section will be described. The voice of the microphone 1 passes through the transmission detecting circuit 2, is amplified by the voice amplifying circuit 3, and an unnecessary band is suppressed by the low pass filter 4. It is input to VCO 6 via 5. Then, the high frequency oscillation output modulated by the VCO 6 is amplified by the transmission amplifier circuit 7 and then transmitted from the antenna 8.

Here, the output from the waveform shaping circuit 13 is connected to the input side of the low-pass filter 4 together with the audio amplifier circuit 3. This waveform shaping circuit 13 is the CPU 1
5 is connected to the output port P1 for the Beep signal and has a rectangular wave shape or a triangular wave shape generated by the CPU 15.
The ep sound (2928 Hz in this embodiment) is converted into a sine wave signal of the same frequency, and specifically, it is a filter circuit. This is to prevent the transmission of unnecessary harmonics by shaping it into a sine waveform. With the above configuration, in the present embodiment, the CPU 15 controls the output port P1 by software so that the sine wave having the same frequency as the Beep signal can be superimposed on the audio signal from the microphone 1 and transmitted.

Next, the receiving section will be described. A radio wave received from the antenna 8 is amplified by the high frequency amplifier circuit 9 and demodulated into a voice signal by the demodulation circuit 10. Then, the sound is amplified by the audio amplifier circuit 11 at a low frequency and then output from the speaker 12.

The output of the demodulation circuit 10 is input to the voice amplifier 11 and the tone decoder 14 as well. The tone decoder 14 is a circuit for detecting the presence / absence of a specific frequency component in the audio signal.
It is composed by. Then, a specific frequency (in this embodiment, set to 2928 Hz which is the frequency of the deep signal)
The H-level signal is output only when the signal is detected. This output is the input port P2 of the CPU 15.
It is connected to the. Therefore, the CPU 15 uses the input port P2
Of the Beep included in the received signal by monitoring
The presence or absence of a signal can be recognized.

Explaining the squelch control means, the output port P3 of the CPU 15 is connected to the audio amplifier circuit 11. When the CPU 15 outputs the H level, the audio amplifier circuit 11 operates to output the audio. In other cases, the sound from the speaker 12 is not output. Therefore, if the output port P3 is controlled by software, the squelch operation (close) and release (open) can be operated. As for the signal from the demodulation circuit 11 to the input port P4, the S / N level of the received signal is calculated by the CPU.
It is used for a voice squelch function (which prevents white noise from being output by closing the squelch when there is no received voice), as will be described later. Further, 16 is a PTT switch used for switching between the receiving and transmitting modes as a transceiver, and 17 is a switching switch for switching the pulse interval and duty ratio of the Beep signal for squelch control.

Next, the operation of this embodiment will be described.

First, the operation of the squelch signal generator of this embodiment will be described. FIG. 2 is a flowchart showing the operation in the transmission mode. When the PTT switch 16 is pressed, the flow shown in the figure is executed. In the figure, Steps S2 to S8 are the Beep signal generating means, and the Be signal is intermittently applied for about 1.5 seconds immediately after the start of transmission.
It generates an ep signal. Then, normal call transmission is performed during steps S9 to S12.

First, in step S1, the apparatus is switched to the transmission mode. In step S2, the counter i is reset. Steps S3 to S8 form a loop, which is repeated n times while incrementing the counter i. That is, in step S3, the output port P1 is controlled to generate a beep sound, which is waited for 50 ms in the waiting time of step S4.
ec continue. Next, the beep sound is stopped in step S3, and this is continued for 100 mSec in step S5. This is repeated n times in steps S7 and S8. Therefore, the beep sound is 50 mSec on and 10
Repeatedly turning off 0 mSec. Then, the value of n is set so that the total time of repetition is about 1.5 seconds. As described above, the Beep signal generating means for generating the intermittent Beep signal in about 1.5 seconds immediately after the start of transmission is configured.

Next, in step S9, the timer built in the CPU 15 is set to 30 seconds. This is for forcibly stopping the transmission when one call transmission time exceeds 30 seconds, and is a function required for a specific low power transceiver for legal reasons. That is, the termination of the call due to the PTT switch 16 being turned off is monitored in step S10, while the time-out of the timer is monitored in step S11. If the time is over, an alarm is sounded to the user in step S12 to switch to the reception mode ( Step S1
3).

The above operation is shown in a timing chart of FIG. According to the figure, the intermittent Beep signal is generated immediately after the start of transmission, and the PTT switch 16
It is shown that the alarm is sounded and the transmission is stopped when the time is over regardless of whether or not is pressed.

Next, the operation of the squelch control device of this embodiment will be described. FIG. 4 is a flowchart showing the operation in the reception mode. The flow in the figure is step S in FIG.
It is executed after switching to the reception mode at 13. In the figure, steps S14 to S17 are detection means, which detect that the detection output of the tone decoder 14 is continuous two or more times at a predetermined pulse interval.
In this way, when it is determined that the transmission is from a specific partner, the squelch is released and the voice is output in step S18. When the end of the call is detected (step S19)
Up to S21) The squelch is closed again to shift to the silent state.

First, in step S14, the input port P2
Is monitored to detect the Beep signal in the received signal. B
When the eep signal is detected, the time from the previous detection to the current detection is checked in step S15 to determine whether the pulse interval is 120 to 192 mSec. In this embodiment, the beep sound on the transmitting side is 50 mSec.
Is turned on and off for 100 mSec repeatedly, so 15
If the pulse interval is 0 mSec, it can be determined that the transmission is by a specific partner, but this is set in consideration of a slight margin. Next, in steps S16 and S17, the second Beep sound pulse is detected. After passing through the above steps S14 to S17, the squelch is released and the voice output is started (step S18). In other words, if the above-mentioned squelch release condition is used, Be of 2928 Hz
Since the ep sound is detected twice or more continuously at a predetermined pulse interval, its reliability is extremely high, and squelch release due to malfunction is virtually impossible.

Next, steps S19 to S21 are the operations while receiving the transmission from the specific partner. In other words, when sending a response from here, PTT switch 1
The transmission mode can be entered by pressing 6 (step S19). When the input port P4 is monitored (step S20) and the S / N drop of the received signal is detected (step S21), it is determined that the other party has completed the transmission and the squelch is closed (step S22). Then, the Beep signal is monitored again until the next transmission start is detected.

The above operation is shown in a timing chart of FIG. According to the figure, immediately after the Beep signal with a predetermined pulse interval is repeated twice in the reception mode (that is, 3).
It is shown that the squelch is released (turned off) at the time of the rising of the second pulse).

It should be noted that, in the above explanation, Be and Be
The ep sound has been described as the repetition of turning on 50 mSec and turning off 100 mSec, but this is the operation when the switch 17 is set to “A”, and when the switch 17 is set to “B”, 50 mSec is turned on and 200 mSec is turned on. It turns off and on. With this, it is possible to select two types of squelch signals, so that the possibility of interference can be further reduced. Similarly, various squelch signals can be prepared by changing the pulse interval and the duty ratio of the Beep signal. It should be noted that these squelch signals can be switched immediately during a call, and the operability is extremely good.

[0028]

As described above, according to the squelch signal generator of the present invention, the intermittent B signal is generated only immediately after the start of transmission.
Since the eep signal is generated to cancel the squelch, an encoder for constantly superimposing a tone signal on a voice signal unlike the conventional CTCSS system is not required. Since the squelch signal is generated by effectively utilizing the function of the CPU, the product can be miniaturized at an extremely low cost. Further, according to the squelch control device of the present invention, unlike the conventional CTCSS system, a complicated decoder for separately detecting a tone signal that is always superimposed on a voice signal is not required, and the configuration is simple. However, it is possible to provide a squelch control device having high reliability and less malfunction. Further, since the squelch control is performed by effectively utilizing the function of the CPU, the cost is low,
The product can be miniaturized because it can be realized only by adding a small tone decoder circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of a wireless telephone device incorporating a squelch signal generator and a squelch controller according to the present invention.

FIG. 2 is a flowchart showing an operation of the wireless telephone device in a transmission mode.

FIG. 3 is a timing chart showing an operation of the wireless telephone device in a transmission mode.

FIG. 4 is a flowchart showing an operation of the wireless telephone device in a reception mode.

FIG. 5 is a timing chart showing an operation of the wireless telephone device in a reception mode.

[Explanation of symbols]

 1 Microphone 2 Transmission detection circuit 3 Voice amplification circuit 4 Low pass filter 5 Variable resistance 6 VCO 7 Transmission amplification circuit 8 Antenna 9 High frequency amplification circuit 10 Demodulation circuit 11 Voice amplification circuit 12 Speaker 13 Waveform shaping circuit 14 Tone decoder 15 CPU 16 PTT switch 17 Changeover switch

Claims (2)

[Claims] 1. A beep signal generating means for intermittently generating a beep signal only during a predetermined time immediately after the start of transmission, a waveform shaping means for shaping the beep signal into a sine wave signal, and the sine wave signal from a microphone. Of the squelch signal generating device, which is configured to be superimposed on the voice signal or switched to the voice signal for transmission. 2. A tone decoder for detecting a Beep signal in a received signal, a detection means for detecting that the detection output of the tone decoder has been consecutive twice or more at a predetermined pulse interval, and a squelch by a command from the detection means. A squelch control device including a squelch control means for canceling.