JP4524889B2 - Communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication device that performs data communication using radio waves, and particularly relates to a communication device that forms a home network at home.
[0002]
[Prior art]
As shown in FIG. 5, a conventional communication apparatus of this type employs a so-called single superheterodyne system using a surface acoustic wave filter (hereinafter referred to as SAW filter) 2, a mixer means 4 and a ceramic filter 5 as receiving means. Yes. Consider a 400 MHz band radio wave that is a specific low-power radio as a transmission / reception signal. Only a signal in the vicinity of the desired signal is selectively amplified by the SAW filter 2 and the high frequency amplifying means 3 from the 400 MHz band high frequency signal input to the antenna 1. The selectively amplified signal is mixed with a signal from a voltage controlled oscillation means (hereinafter referred to as VCO) 10 by a mixer means 4. The ceramic filter 5 selectively extracts only the 450 kHz signal, amplifies the 450 kHz signal by the amplifying means 6, and performs the demodulation processing by the demodulating means 7. Here, 450 KHz which is the output of the mixer means 4 is called an intermediate frequency signal.
[0003]
At the time of transmission, the output of the VCO 10 is amplified by the transmission means 9, and then radio waves are radiated from the antenna 1 via the switching means 8.
[0004]
[Problems to be solved by the invention]
However, in the above conventional communication apparatus, the frequency of the local oscillation signal at the time of reception and the frequency of the desired reception signal are at most 450 KHz apart, and when a large input reception signal is input to the antenna 1, the oscillation frequency of the VCO 10 There is a problem that the frequency is disturbed by being pulled by the received signal. Further, when an interference signal near the local oscillation signal frequency is input to the antenna 1 as a signal input to the antenna 1, the oscillation frequency of the VCO 10 is greatly disturbed. Therefore, there has been a problem that an accurate demodulation operation cannot be performed.
[0005]
Further, at the time of transmission, a signal obtained by amplifying the oscillation signal of the VCO 10 is radiated from the antenna 1, and as a result, part of the radiated energy is fed back to the VCO 10 to disturb the frequency or deteriorate C / N.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention has a receiving means for receiving a high-frequency signal and a frequency synthesizer means for selecting a channel. The frequency synthesizer means outputs a voltage-controlled oscillator and an oscillation output of the voltage-controlled oscillator as one. 1 / N frequency dividing means for dividing / N (N> 1), and a signal from the 1 / N frequency dividing means is supplied to the receiving means as a local oscillation signal.
[0007]
According to the above-described invention, since a signal having a frequency 1 / N times the VCO is used as the local oscillation signal, the frequency of the local oscillation signal is not disturbed even when a large input reception signal is input.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
A communication apparatus according to the present invention includes a receiving unit that receives a high-frequency signal, a transmitting unit that amplifies and outputs the high-frequency signal, and a frequency synthesizer unit that performs channel selection, and constitutes the frequency synthesizer unit during reception. A signal from 1 / N frequency dividing means that divides the oscillation output of the voltage controlled oscillator to 1 / N (N> 1) is supplied to the receiving means as a local oscillation signal. The signal from the means is supplied to the transmission means as a transmission signal .
[0009]
Since a signal having a frequency 1 / N times the VCO is used as the local oscillation signal, the frequency of the local oscillation signal is not disturbed even when a large input reception signal is input. Further, since a signal having a frequency 1 / N times that of the VCO is used as the transmission signal, even if a part of the energy of the transmission signal is fed back to the VCO, the frequency of the transmission signal is not disturbed.
[0012]
The communication apparatus according to the present invention includes a receiving means for receiving a radio frequency signal, comprising: a transmitting means for amplifying the high frequency signal output, and a frequency synthesizer means for performing channel selection, the frequency synthesizer means during reception A signal from an N multiplying means for multiplying the oscillation output of the voltage controlled oscillator constituting N by N (an integer of N> 1) is supplied to the receiving means as a local oscillation signal ;
At the time of transmission, the signal from the 1 / N frequency dividing means is supplied to the transmitting means as a transmission signal .
[0013]
Since a signal having a frequency N times the VCO is used as the local oscillation signal, the frequency of the local oscillation signal is not disturbed even when a large input reception signal is input. Further, since a signal having a frequency N times the VCO is used as the transmission signal, the frequency of the transmission signal is not disturbed even if a part of the energy of the transmission signal is fed back to the VCO.
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
Example 1
1 is a block diagram illustrating a communication apparatus according to a first embodiment of the present invention. In FIG. 1, 1 is an antenna, 2 is a SAW filter, 3 is high frequency amplification means, 4 is mixer means, 51 is a channel filter, 6 is amplification means, 7 is demodulation means, 8 is transmission / reception switching means, and 9 is a high frequency signal. Transmitting means for amplifying and outputting 10 is VCO, 11 is first dividing means, 12 is phase comparing means, 13 is second dividing means, 14 is a crystal oscillator, 15 is a loop filter, and 20 is 1/2 Dividing means. The crystal oscillator includes a crystal 16, a capacitor 17, and a capacitor 18. Reference numeral 30 denotes reception means for receiving a high-frequency signal, and reference numeral 31 denotes frequency synthesizer means for performing channel selection. The same functional blocks as those in the conventional example of FIG.
[0020]
Next, the operation and action will be described. First, a case where a specific low-power radio wave in the 400 MHz band is received as a desired signal will be described. The radio wave input to the antenna 1 is applied to the SAW filter 2 by the switching means 8. Then, the high frequency amplification means 3 amplifies the 400 MHz band radio wave, and then inputs it to the mixer means 4. The oscillation signal from the VCO 10 is divided by ½ by the ½ divider 20. The output of the 1/2 frequency dividing means 20 is used as a local oscillation signal of the mixer means 4. The local oscillation frequency is a frequency separated from the reception frequency desired to be received by the antenna 1 by 50 KHz. As for the output of the mixer means 4, only the desired signal is selected and extracted by the channel filter 51. The center frequency of the channel filter 51 is 50 KHz. Accordingly, the oscillation frequency of the VCO 10 is removed twice as much as the local oscillation frequency, ie, 80. Amplifying means 6 amplifies the desired signal, and demodulating means 7 performs demodulation processing. Since the center frequency of the channel filter 51 is as low as 50 KHz, it can be easily configured with an active filter or a switched capacitor filter. That is, it can be configured using a semiconductor.
[0021]
Next, a method for creating a local oscillation signal will be described in more detail. The signal oscillated by the VCO 10 is divided by 1/2 by the 1/2 divider 20 and divided by 1 / N times by the first divider 11. On the other hand, the signal oscillated by the crystal oscillator 14 is frequency-divided by 1 / M times by the second frequency divider 13 and becomes a 12.5 KHz reference signal input to the phase comparator 12. The phase comparator 12 detects a phase error of a signal obtained by dividing the 12.5 KHz reference signal and the VCO signal by 1 / (2 × N), and passes the loop filter 15 so that the phase error becomes zero. Controls oscillation frequency and phase. Therefore, the oscillation frequency of the VCO is 2 × N times 12.5 KHz. Therefore, the local oscillation signal fL which is the output of the 1/2 frequency dividing means 20 is N times 12.5 KHz. Here, by varying N, the oscillation frequency of the local oscillation signal fL can be varied in 12.5 KHz steps. According to the configuration of the present embodiment, even when a large input desired signal is input to the antenna, the oscillation frequency of the VCO 10 is a signal that is far away in frequency and does not disturb the oscillation frequency of the VCO 10.
[0022]
Next, consider the time of transmission. At the time of transmission, the output signal of the 1/2 frequency dividing means 20 is amplified by the transmitting means 9 and radiated from the antenna 1 via the switching means 8. The transmission signal frequency can be obtained by changing the frequency division number N of the first frequency dividing means 11. That is, it is possible to radiate an arbitrary radio wave in a signal sequence having a channel interval of 12.5 KHz. In the case of FM modulation, both the oscillation frequency of the VCO 10 and the oscillation frequency of the crystal oscillator 14 are modulated, but the modulation degree is adjusted so as to become a prescribed modulation degree at the output of the 1/2 frequency dividing means 20. There is a need to. According to the configuration of this embodiment, even if a part of the energy radiated from the antenna 1 is fed back to the VCO 10, it is far from the oscillation frequency of the VCO 10, and does not disturb the oscillation frequency of the VCO 10.
[0023]
(Example 2)
FIG. 2 is a block diagram showing a communication apparatus according to the second embodiment of the present invention.
[0024]
In the second embodiment, the same functional blocks as those in the block diagram shown in FIG. The difference from FIG. 1 which is the first embodiment is that the frequency multiplication means 21 is used in FIG. 2 which is the present embodiment instead of the 1/2 frequency dividing means 20 in FIG. By using the doubling means 21, 2 / N times the oscillation frequency of the VCO 10 is controlled to be equal to 12.5 KHz. Therefore, since the local oscillation frequency or transmission frequency is twice the oscillation frequency of the VCO 10, it is controlled to N times 12.5 KHz. Since the local oscillation frequency or transmission frequency is a signal in the 400 MHz band, the oscillation frequency of the VCO 10 is in the 200 MHz band. According to the configuration of the present embodiment, as in the case of the first embodiment, even when a large input desired signal is input to the antenna, the oscillation frequency of the VCO 10 is a signal far from the frequency and disturbs the oscillation frequency of the VCO 10. There is nothing. Even during transmission, even if part of the energy radiated from the antenna 1 is fed back to the VCO 10, it is far from the oscillation frequency of the VCO 10 and does not disturb the oscillation frequency of the VCO 10.
[0025]
(Example 3)
FIG. 3 is a block diagram showing a communication apparatus according to Embodiment 3 of the present invention.
[0026]
In the third embodiment, the same functional blocks as those in the block diagram shown in FIG. A different part from FIG. 1 which is Example 1 is that a direct conversion system is used as a reception system. 22 is a direct conversion mixer means, 23 is a first filter, 24 is a second filter, and 25 is a demodulation means. The frequency of the local oscillation signal that is the output of the 1/2 frequency dividing means 20 is the same as the frequency of the desired signal that is desired to be received. The I and Q signals, which are orthogonal baseband signals, are output to the output of the direct conversion mixer means 22, and only the desired signal is extracted by the first filter 23 and the second filter 24 and demodulated by the demodulation means 25. The The direct conversion reception system shown in the present embodiment does not require a SAW filter for removing the image signal, and the output of the direct conversion mixer means is a baseband signal, so that the first filter 23 and the second filter 24 The demodulating means 25 can be easily configured with a semiconductor circuit. Therefore, there is a merit that it can be made at low cost. However, when a large input signal is input, there is a problem that the local oscillation frequency is disturbed and the demodulation performance deteriorates. According to the configuration, even when a desired signal having a large input is input to the antenna, the oscillation frequency of the VCO 10 is a signal that is far away in frequency and does not disturb the oscillation frequency of the VCO 10. Even during transmission, even if part of the energy radiated from the antenna 1 is fed back to the VCO 10, it is far from the oscillation frequency of the VCO 10 and does not disturb the oscillation frequency of the VCO 10.
[0027]
Example 4
FIG. 4 is a block diagram showing a communication apparatus according to Embodiment 4 of the present invention.
[0028]
In the fourth embodiment, the same numbers are assigned to the same functional blocks as those in the block diagram shown in FIG. The difference from FIG. 3 which is the third embodiment is that the frequency multiplication means 21 is used in FIG. 4 which is the present embodiment instead of the 1/2 frequency dividing means 20 in FIG. By using the doubling means 21, 2 / N times the oscillation frequency of the VCO 10 is controlled to be equal to 12.5 KHz. Therefore, since the local oscillation frequency or transmission frequency is twice the oscillation frequency of the VCO 10, it is controlled to N times 12.5 KHz. Since the local oscillation frequency or transmission frequency is a signal in the 400 MHz band, the oscillation frequency of the VCO 10 is in the 200 MHz band. According to the configuration of the present embodiment, as in the case of the first embodiment, even when a large input desired signal is input to the antenna, the oscillation frequency of the VCO 10 is a signal far from the frequency and disturbs the oscillation frequency of the VCO 10. There is nothing. Even during transmission, even if part of the energy radiated from the antenna 1 is fed back to the VCO 10, it is far from the oscillation frequency of the VCO 10 and does not disturb the oscillation frequency of the VCO 10.
[0029]
In the first to fourth embodiments, the output of the 1/2 divider 20 or the doubler 21 is used for the local oscillation signal and the transmission signal. However, the 1 / N divider 20 or the N multiplier 21 may be used. . Here, N may be an integer.
[0030]
【The invention's effect】
As described above, the communication apparatus according to the present invention has the receiving means and the frequency synthesizer means for performing channel selection, and the frequency synthesizer means divides the voltage-controlled oscillator and the oscillation output of the voltage-controlled oscillator. A signal obtained by dividing the output of the voltage controlled oscillator by 1 / N (an integer of N> 1), and having phase dividing means and phase comparing means for detecting a phase error between the output of the variable dividing means and a reference signal Is supplied to the receiving means as a local oscillation signal, there is an effect that the frequency of the local oscillation signal is not disturbed even when a large input reception signal is input.
[0031]
The communication apparatus according to the present invention further includes a transmission means and a frequency synthesizer means for performing channel selection, and the frequency synthesizer means includes a voltage controlled oscillator and a frequency dividing means for dividing the oscillation output of the voltage controlled oscillator. Phase comparison means for detecting a phase error between the output of the variable frequency dividing means and the reference signal, and a signal obtained by dividing the output of the voltage controlled oscillator by 1 / N (N> 1) is used as a transmission signal. Since it is configured to supply to the transmission means, there is an effect that the frequency of the transmission signal is not disturbed even if part of the energy of the transmission signal is fed back to the VCO.
[0032]
The communication apparatus according to the present invention further includes a receiving unit and a frequency synthesizer unit for performing channel selection, and the frequency synthesizer unit includes a voltage controlled oscillator and a frequency dividing unit that divides the oscillation output of the voltage controlled oscillator. Phase comparison means for detecting a phase error between the output of the variable frequency dividing means and the reference signal, and receiving means using a signal obtained by multiplying the output of the voltage controlled oscillator by N (an integer of N> 1) as a local oscillation signal Therefore, the frequency of the local oscillation signal is not disturbed even when a large input reception signal is input.
[0033]
The communication apparatus according to the present invention further includes frequency synthesizer means for selecting a channel, and the frequency synthesizer means is a voltage controlled oscillator, frequency dividing means for dividing the oscillation output of the voltage controlled oscillator, and the variable frequency divider. A phase comparison means for detecting a phase error between the output of the circumference means and the reference signal, and a signal obtained by multiplying the output of the voltage controlled oscillator by N (an integer of N> 1) is supplied to the transmission means as a transmission signal Therefore, even if a part of the energy of the transmission signal is fed back to the VCO, there is an effect that the frequency of the transmission signal is not disturbed.
[0034]
Further, the receiving means of the communication apparatus according to the present invention is composed of a direct conversion receiver using the same frequency as the desired signal to be received as a local oscillation signal. There is an effect that a conversion receiver can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a communication apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram of a communication apparatus according to a second embodiment of the present invention. 4 is a block diagram of a communication apparatus according to a fourth embodiment of the present invention. FIG. 5 is a block diagram of a conventional communication apparatus.
DESCRIPTION OF SYMBOLS 1 Antenna 2 SAW filter 3 High frequency amplification means 4 Mixer means 8 Switching means 9 Transmission means 10 Voltage control oscillation means (VCO)
DESCRIPTION OF SYMBOLS 11 1st frequency dividing means 12 Phase comparison means 13 2nd frequency dividing means 14 Crystal oscillator 15 Loop filter 20 1/2 frequency dividing means 21 2 frequency multiplication means 22 Direct conversion mixer means 23 1st filter 24 2nd filter 25 demodulating means 30 receiving means 31 frequency synthesizer means 51 channel filter

Claims (2)

Receiving means for receiving a high-frequency signal;
A transmission means for amplifying and outputting a high-frequency signal;
Frequency synthesizer means for performing channel selection,
The frequency synthesizer means is part of its components,
1 / N frequency dividing means for dividing the oscillation output of the voltage controlled oscillator by 1 / N (N> 1),
A crystal oscillator,
A phase error between the phase of the signal obtained by further dividing the signal from the 1 / N frequency dividing means and the phase of the signal obtained by further dividing the signal from the crystal oscillator is detected, and the phase error is detected through a loop filter. And a comparison means for feeding back to the voltage controlled oscillator,
And characterized in that during reception is supplied to the reception means a signal from the 1 / N frequency division means as a local oscillation signal, at the time of transmission was fed to the transmission unit as a transmission signal a signal from the 1 / N divider means Communication device. Receiving means for receiving a high-frequency signal;
A transmission means for amplifying and outputting a high-frequency signal;
Frequency synthesizer means for performing channel selection,
The frequency synthesizer means is part of its components,
N multiplying means for multiplying the oscillation output of the voltage controlled oscillator by N (N> 1),
A crystal oscillator,
A phase error between the phase of the signal obtained by further dividing the signal from the N multiplication means and the phase of the signal obtained by further dividing the signal from the crystal oscillator is detected, and the phase error is detected via the loop filter. A comparison means for returning to the controlled oscillator,
The supply signal from the N multiplying means to the receiving means as a local oscillation signal at the time of reception, the communication apparatus at the time of transmission, characterized in that supplied to the transmission unit as a transmission signal a signal from the 1 / N divider means .

Images