JPH11284524A - wireless device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a synthesizer-type wireless device that modulates a signal with a VCO, since the modulation frequency characteristic of the VCO is an HPF characteristic, a sound of 300 to 500 Hz near a cutoff frequency is 1 kHz in a high frequency band. Frequency. For this reason, in the case of a sound of 300 to 500 Hz which is a rectangular wave including a fundamental wave and harmonics such as 3 times and 5 bytes, since the fundamental wave is attenuated when modulated, the modulated waveform is distorted with a peak. Waveform. There is a problem that the modulation degree becomes higher than that of the original voice due to this peak. SOLUTION: A modulation signal is input to both a VCO and a reference oscillator, and a reduced frequency component attenuated by the modulation of the VCO is supplemented by the modulation of the reference oscillator to make the modulation frequency characteristic constant from the reduction to the high frequency range. As a result, even when a rectangular waveform has a reduced component and a high-frequency component, distortion generated in the modulated waveform is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio having a frequency synthesizer including a reference oscillator, a phase comparator, a loop filter, and a VCO.

[0002]

2. Description of the Related Art Conventionally, a radio apparatus using a PLL synthesizer system has a VCO 4 and a reference oscillator 1 which receive only an audio signal 6 and a tone signal 5 as modulation inputs, respectively, as shown in FIG. doing. Usually, the modulation frequency characteristic of the reference oscillator is the modulation characteristic 11 of the reference oscillator of FIG.
And the modulation frequency characteristic of the VCO is
It becomes an HPF type like the modulation characteristic 10 of the VCO in FIG.
However, since voice uses the band of 300 to 3 kHz and tone uses the band of about 60 to 250 Hz,
A voice is input to the VCO having the HPF characteristic, and a tone signal is input to the LPF type reference oscillator as a modulation input.

[0003] In the vicinity of the cut-off frequency of the modulation characteristic of the VCO, the level is lower than the pass band, and the reduced sound of 300 to 500 Hz in the vicinity of the cut-off frequency is higher than that of the pass band.
The degree of modulation is lower than that of sound near kHz. Here, when a rectangular wave including a high-frequency component such as three times or five times the fundamental wave is input, the level of the fundamental wave is reduced and the level of the high-frequency component remains unchanged, so that the modulation waveform of only the VCO shown in FIG. It becomes a distorted waveform having a peak like the modulation waveform 12. For this reason, the degree of modulation is higher than the actual voice by the amount of the peak that jumps out.

[0004]

As described above, in a conventional wireless device, when a rectangular wave including a high frequency component of three times or five times the fundamental wave is input, the modulated waveform is distorted with a peak. There was a problem of a wavy waveform. SUMMARY OF THE INVENTION It is an object of the present invention to solve this problem, and to provide a wireless device that compensates for the attenuation of the reduction and suppresses the distortion of the modulated waveform of the rectangular wave.

[0005]

According to the present invention, in order to achieve the above-mentioned object, both a tone signal and a voice signal are inputted as modulation signals to each of a VCO and a reference oscillator.

[0006]

FIG. 1 shows an embodiment of the present invention.
In the block diagram of FIG. 1, the tone signal 5 and the audio signal 6
Are combined by the amplifier 13 to obtain modulation inputs of both the reference oscillator 1 and the VCO 4. The gains of the amplifiers 9 and 13 are determined by the modulation sensitivity of the VCO 4 and the reference oscillator 1. The amplifier 9 is adjusted to balance the tone and voice modulation. The modulation levels of the tone and the voice are adjusted to prescribed levels by adjusting the gains of the amplifiers 7 and 8, respectively. The frequency component near the cut-off wave number, which is attenuated by the modulation characteristic 11 of the VCO, is supplied to the reference oscillator 1 so that the level is compensated by the modulation characteristic 11 of the reference oscillator shown in FIG. Even in the case of the above, there is no distortion such as a peak popping out like the modulation waveform 12 of only the VCO in FIG.

[0007]

According to the present invention, by inputting voice modulation to both the VCO and the reference oscillator, a modulation waveform without distortion can be obtained even when a rectangular wave is used as the modulation input.

[Brief description of the drawings]

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

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

FIG. 3 is an example of a modulation frequency characteristic of a VCO and a reference oscillator.

FIG. 4 is an example of a modulation waveform when modulated only by a VCO.

[Explanation of symbols]

1: reference oscillator, 2: phase comparator, 3: loop filter, 4: VC
O, 5: tone signal output, 6: audio signal output, 7-9, 13: amplifier, 10:
VCO modulation frequency characteristics, 11: reference oscillator modulation frequency characteristics, 12: VCO-only modulation waveform.

Claims (1)

[Claims] 1. A radio having a frequency synthesizer including a reference oscillator, a phase comparator, a loop filter, and a VCO, wherein both a tone signal and an audio signal are input to each of the VCO and the reference oscillator as a modulation signal. The radio configured.