JP2848063B2 - Digital radio equipment with noise suppression - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital radio apparatus for suppressing noise, and more particularly to a digital radio apparatus for radio communication for suppressing noise generated during an asynchronous period until a modem unit establishes synchronization.

[0002]

2. Description of the Related Art Conventionally, this kind of digital radio apparatus has
As shown in FIG. 2, it comprises a digital signal processing device 11 and a wireless transmission / reception device 12. Digital signal processor 1
Reference numeral 1 denotes a device which is interfaced with a voice input / output unit of the wireless transmission / reception unit 12 and enables digitized voice communication.
It comprises a signal converter 1 having a D converter and a D / A converter for converting a serial digital signal into a voice signal, and a modem 2 for converting a serial digital signal into a modem signal and a modem signal into a sialyl digital signal. .

The operation of this radio apparatus will be described with reference to the signal timing chart of FIG. At the time of transmission, the audio signal 101 is input from the microphone 8 to the signal converter 1, converted into a serial digital signal 102 having a synchronization signal, further modulated into a modem signal 103 in the modem 2, and sent to the wireless transceiver 12. Radiated from the antenna as radio waves.

At the time of reception, a signal received by the antenna is input to the radio transmission / reception unit 12, demodulated into a modem signal 103, and input to the digital signal processing device 11. The modem signal 103 is demodulated by the modem 2, output as a serial digital signal 104, converted to an audio signal 105 by the signal converter 1, and output to the speaker 9.
The modem signal referred to here is a signal obtained by converting a digital signal into an analog signal by a generally well-known FSK method.

[0005]

In such a conventional digital radio apparatus, a synchronization signal included in a serial digital signal 104 from a transmitting side is detected, and the serial digital signal 104 is converted based on the detected synchronization signal. The signal is converted into an audio signal 105 and output to the speaker 9.
For this reason, the serial digital signal 104 is converted into the audio signal 105 until the synchronization signal is detected, that is, during the synchronization is not established.
The sound is output from the speaker 9 as it is without being converted into a sound, and this sound is output from the speaker 9 as noise, which causes a problem that the operator is uncomfortable. SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital radio apparatus capable of suppressing noise until synchronization is established.

[0006]

According to the present invention, there is provided a digital radio apparatus comprising: a modulation / demodulation unit for demodulating a received signal; a signal conversion unit for converting the demodulated signal into an audio signal; and a synchronization unit for detecting a synchronization signal in the received signal. A detection unit, a CW detection unit that detects a CW signal in the reception signal, and on / off control of a switch based on a detection signal from the synchronization detection unit and a detection signal from the CW detection unit, and from the signal conversion unit to a speaker. And a switch control unit for intermittently outputting the output signal. The switch control unit turns off the switch when the synchronization signal detection signal from the synchronization detection unit is not input so that the signal from the signal conversion unit is not output to the speaker, and the CW detection signal from the CW detection unit is input. Sometimes, the switch is turned on intermittently so that the signal from the signal converter is output intermittently to the speaker.

[0007]

According to the present invention, noise is prevented by preventing sound from being output from the speaker until synchronization is established. During this time, when a CW signal is detected, a sound is output intermittently from a speaker and output in a state where noise is suppressed.

[0008]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.
In FIG. 1, the digital radio apparatus includes a radio transmission / reception unit 6 connected to an antenna and a digital signal processing device 7. The digital signal processing device 7 includes a microphone 8
A / D that converts the audio signal of the
A signal converter 1 having a converter (not shown), a D / A converter (not shown) for converting a serial digital signal into an audio signal and outputting it to a speaker 9; a serial digital signal as a modem signal, and vice versa. And a modulation / demodulation unit 2 for converting the data into the data.

Further, the digital signal processor 7 has a synchronous signal detecting section 3 for detecting a synchronous signal in the received signal.
Signal detection unit 4 for detecting a CW signal in the received signal
It has. Then, the outputs of the detection units 3 and 4 are input to a SW (switch) control unit 5, respectively. The SW control unit 5 is provided with a logical sum gate (OR gate) 51 and a switch 52. When the output of at least one of the detection units 3 and 4 is input to the logical sum gate 51, the switch 52 is turned on. , So as to be turned off. This switch 52 connects and disconnects the speaker 9 to and from the signal converter 1.

Next, the operation of the digital radio apparatus having the above configuration will be described with reference to the time chart of FIG. still,
Since the transmission is the same as that of the conventional device, the description is omitted. Now, when a radio wave transmitted along with the transmission press signal 106 on the transmission side is received through the antenna, the received signal is demodulated by the radio transmission / reception unit 6 and the modem signal 10
3 and input to the digital signal processor 7. In the digital signal processing device 7, the modem signal 103 is converted into a serial digital signal 104 by the modem 2 and output to the signal converter 1. The signal converter 1 outputs an audio signal 105.

At the same time, the serial digital signal 104
Is output to the synchronization detection unit 3 and the modem signal 103 is output to the CW detection unit 4. The synchronization detection section 3 detects a synchronization signal in the serial digital signal 104 and outputs a detection output signal 107 to the SW control section 5. The CW detection unit 4 detects the CW signal in the modem signal 103 and outputs a CW detection output signal 108 to the SW control unit 5 after a predetermined time T2. This time T2 is set in accordance with the signal processing time of the signal converter 1 that can detect the synchronization signal.

The SW control unit 5 opens and closes the switch 52 after taking the logical sum of the two detection output signals by the OR gate 51. That is, the time T1 until the synchronization is established
During this period, the switch 52 is turned off. As a result, the audio signal 105 from the signal conversion unit 1 is not input to the speaker 9, and therefore, during the time T1 until this synchronization is established, the random signal a in the serial digital signal 104 is converted into a signal. Output to the signal conversion unit 1
This prevents the noise in the audio signal 105 from being output to the speaker 9.

On the other hand, if the state where the synchronization is not established continues, no sound signal 105 is output from the speaker 9 together with the noise, so that the speaker 9 remains silent, and the operator determines whether there is a signal from the transmitting side. Or, the presence or absence of an abnormality in the digital signal processing device 7 cannot be recognized. Therefore, the CW detection unit 4 outputs the CW signal 1 in the modem signal 103.
The CW detection output signal 108 is output when a predetermined time T2, which can be arbitrarily set, elapses.

When the CW detection output signal 108 is input to the SW controller 5, the switch 52 is turned on and off intermittently. For this reason, the audio signal 105 is output from the speaker 9 by this intermittent on operation, and noise is also output at the same time. However, the noise was suppressed by appropriately setting the duty ratio of the intermittent on and off. Noise b in the state
Can be output from the speaker 9. As a result, the operator confirms the noise that is not harsh, so that the digital signal processing device 7 operates normally.
It is possible to recognize that synchronization is not established at present.

[0015]

As described above, according to the present invention, the sound is not output from the speaker until the synchronization is established, thereby preventing noise and eliminating discomfort to the operator. Further, when a CW signal is detected during this time, a sound can be output intermittently from a speaker and output in a state where noise is suppressed, so that normal operation of the device can be recognized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a wireless device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional wireless device.

FIG. 3 is a signal waveform diagram in the present invention and each conventional wireless device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal conversion part 2 Modulation / demodulation part 3 Synchronization detection part 4 CW detection part 5 SW control part 6 Wireless transmission / reception part 7 Digital signal processing device 8 Microphone 9 Speaker

Claims (1)

(57) [Claims] 1. A modulation and demodulation unit having a function for demodulating a received signal, the signal conversion unit of the demodulated signal to the audio signal, and a synchronization detector for detecting a synchronization signal in the received signal, the received signal a CW detector for detecting the CW signal in the on switch by the detection signal from the detection signal and the CW detector from the synchronization detection unit, the off control signal output to the speaker from the signal converter A digital signal processing device including a switch control unit for intermittent switching , wherein the switch control unit receives a signal from the synchronization detection unit.
When the synchronization signal detection signal is not input,
Off to output the signal from the signal converter to the speaker.
No CW detection signal from the CW detection unit is input
When the switch is turned on intermittently, the signal conversion is performed.
So that the signal from the unit is output intermittently to the speaker
Noise suppression type digital radio apparatus characterized by constituting the.