JP2525409Y2 - Wireless telephone equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless telephone device for performing wireless communication between a master unit and a slave unit.

[0002]

2. Description of the Related Art In recent years, eavesdropping during wireless communication has become a social problem in this type of wireless telephone device, and research and development for improving its secrecy have been actively conducted. Generally, in this kind of cordless telephone device, the third
As a confidential method for preventing eavesdropping by a person, a voice spectrum inversion method is frequently used. The audio spectrum inversion method is a method to replace the audio spectrum 300～3400H _Z to 3400～300H _Z, on the transmission side, the audio input signal (300~3400H _Z) band-limited, the sub-carrier (about 3300~3600H Perform amplitude modulation in _Z ). By this modulation, the modulated wave spectrum becomes DSB (double sideband), and if only LSB (lower sideband) is extracted by a filter,
A signal whose spectrum is inverted as shown in FIG. 3 is obtained. On the receiving side, the amplitude modulation is performed again on the subcarriers as in the transmitting side. Then, the spectrum becomes DSB due to this modulation, and a signal whose spectrum is inverted again (a signal whose spectrum is equivalent to the original input signal) is obtained on the LSB side. If only the LSB is extracted from this DSB wave by a filter, a received and reproduced signal can be obtained. However, such a voice spectrum inversion method may cause deterioration in sound quality. As a countermeasure against this, a confidential mode for performing a spectrum inversion of a voice signal using a circuit having a configuration as shown in FIG. 2 and no spectrum inversion are performed. The mode is switched to the normal mode to prevent deterioration of sound quality.

[0003]

SUMMARY OF THE INVENTION In a conventional wireless telephone apparatus, when a secret mode and a normal mode are switched and used, a gain and a gain in the secret mode in a secret circuit composed of a scramble section and a descramble section are considered. since the gain difference frequency between the gain in the normal mode occurs, it is difficult to <br/> volume by the operation of the compander when switching both modes are used by switching the change significantly both modes on the real quality There was a disadvantage of becoming.

[0004]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides a radio section for modulating and demodulating the frequency of an audio signal transmitted / received between a master unit and a slave unit, and a secret story showing audio spectrum inversion. A secret section comprising a scramble section for processing an input audio signal by switching between a mode and a normal mode indicating audio spectrum non-inversion, and a descrambling section for demodulating an audio signal subjected to audio spectrum inversion / non-inversion processing, and a radio section. And a compander section disposed between the communication section and the secret talk section to reduce noise at the time of frequency modulation / demodulation of the radio section.

[0005]

[Action] audio signal from the transmitter, after the mode switching of the privacy mode and the normal mode is the spectrum inversion and non-inversion processing is performed in the privacy section, U-compander unit
The signal amplitude is compressed by the compensator , further frequency-modulated in the radio unit, and transmitted to a partner device such as a slave unit. Conversely, the spectrum-inverted / non-inverted signal transmitted from the partner device and frequency-modulated is subjected to frequency demodulation in the radio unit and further to the compander unit .
FM (frequency modulation and demodulation)
After the transmission noise is reduced, the signal is demodulated as a normal signal in the secret part and transmitted to the receiver. As a result, both the spectrum inversion signal and the non-inversion signal pass through the compander section before the privacy section, so that the gain difference in the privacy section is not enlarged, and
Therefore, a change in volume at the time of switching between spectrum inversion and non-inversion is prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the wireless telephone device according to the present invention. In FIG. 1, reference numeral 1 denotes an audio processing unit, and reference numeral 2 denotes a secret story composed of a scrambling unit for alternately inverting and non-inverting the spectrum of the audio signal based on the switching signal and a descrambling unit for demodulating the spectrum-inverted and non-inverted signal. The circuit unit 3 is a compander unit composed of a compressor and an expander that suppresses noise at the time of frequency modulation and demodulation by the radio unit 4 described later. The compander unit 4 is composed of a transmitting unit and a receiving unit, and is transmitted / received to / from a partner device such as a slave unit. Reference numeral 5 denotes a microphone, 6 is a speaker, and A is an antenna.

The arrangement position of the compander 3 is different between this radio telephone apparatus and the conventional radio telephone apparatus shown in FIG. That is, conventionally, in order to suppress noise at the time of frequency modulation / demodulation of a wireless telephone device, a compander unit 3 including a compressor on the transmission side and an expander on the reception side is arranged between the voice processing unit 1 and the privacy circuit unit 2. ing. As a result, the gain difference between the audio signal in the privacy mode (ie, when the spectrum is inverted) and the audio signal in the normal mode (ie, when the spectrum is not inverted) demodulated in the descrambling unit in the privacy circuit 2 is further increased. Since the expander amplifies to increase the gain, conventionally, the gain difference is further increased, and there is a drawback that the sound volume changes remarkably when both modes are switched. The wireless telephone device of the present invention
The compander section 3 is arranged between the privacy circuit section 2 and the radio section 4 so that both signals in the normal mode and the privacy mode can pass through the compander section 3, thereby reducing the gain difference between the two modes. This is to reduce the volume difference at the time of mode switching.

Hereinafter, the operation of the wireless telephone device will be described. The scramble section in the secret talk circuit section 2 inputs a voice signal (transmitted signal) from the microphone 5 after voice processing, and converts this voice signal into a normal voice signal (spectrum non-inverted signal).
And alternately output as a spectrum-inverted signal. The voice spectrum inverted / non-inverted signal is transmitted to the radio unit 4 with its noise suppressed by a compressor in the compander unit 3, subjected to frequency modulation in the transmission unit in the radio unit 4, And so on. On the other hand, the audio signal which has been subjected to audio spectrum inversion / non-inversion and frequency-modulated and transmitted by the partner device is received by the receiving unit of the radio unit 4 via the antenna A, and further subjected to frequency demodulation by this receiving unit. It is processed and sent to the expander in the compander unit 3. Then, the expander removes the noise at the time of frequency demodulation, and sends out the demodulated signal to the descrambling unit in the secret communication circuit unit 2 for demodulation. That is, in the descrambling unit, a signal that is not spectrum-inverted is passed through as it is, and the spectrum-inverted signal is demodulated and sent to the audio processing unit 1 as a normal audio signal. Thus, the normal audio signal that has passed through the descrambling unit is further subjected to audio processing in the audio processing unit 1 and transmitted to the speaker 6. As described above, in this radiotelephone apparatus, the voice signal demodulated in the secret talk circuit section 2 is not amplified because both the spectrum inversion signal and the non-inverted signal pass through the compander section 3, so that the secret talk mode is switched from the normal mode. The change in volume at the time of switching to the mode and at the time of switching from the secret mode to the normal mode can be reduced.

[0009]

As described above, in the present invention, since the compander section is arranged between the radio section and the privacy section, both the spectrum inversion signal and the non-inversion signal pass through the compander section. As a result, the voice signal demodulated in the confidential section is not amplified, so the spectrum inversion and
There is an effect that the volume change at the time of non-inversion switching can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a conventional wireless telephone device.

FIG. 3 is an explanatory diagram illustrating an audio spectrum inversion method.

[Explanation of symbols]

 Reference Signs List 1 voice processing unit 2 secret talk circuit unit 3 compander unit 4 wireless unit 5 microphone 6 speaker A antenna

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-77233 (JP, A) JP-A-63-275234 (JP, A) JP-A-52-39302 (JP, A) 13980 (JP, B2) Transactions of the Institute of Electronics, Communications and Engineers, '81 / 5 VOL. J64-B NO. 5P. 425-432 "Speech quality improvement effect of compander and emphasis in speech spectrum H inverted narration"

Claims (1)

(57) [Scope of request for utility model registration] 1. A wireless telephone device comprising a master unit and a slave unit and performing wireless communication between the master unit and the slave unit, a wireless telephone for performing frequency modulation and demodulation of an audio signal transmitted and received between the master unit and the slave unit. Section, a scramble section for processing an input audio signal by switching between a secret mode indicating voice spectrum inversion and a normal mode indicating voice spectrum non-inversion, and a descrambler for demodulating a voice signal subjected to voice spectrum inversion / non-inversion processing. And a compander section disposed between the radio section and the secrecy section to reduce noise during frequency modulation and demodulation of the radio section.