JP2011109518A - Transmitting and receiving apparatus, and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitting and receiving apparatus that is compact and high in operating speed and accuracy, and is able to attain communication, such as frequency hopping, corresponding to various modulation methods. <P>SOLUTION: The transmitting and receiving apparatus includes a direct digital synthesizer for generating a modulation signal and a carrier signal; a transmitting means for transmitting the modulation signal generated by the direct digital synthesizer; a receiving means for receiving a reception signal; a reception mixer that uses the carrier signal generated by the direct digital synthesizer for converting the reception signal into a base band signal or into an intermediate frequency signal by frequency; and a sampling filter having a variable band that suppresses unwanted frequency components from the base band signal or the intermediate frequency signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transceiver having a frequency hopping function or the like used for a radio device or the like.

  FIG. 5 is a diagram illustrating a configuration of a conventional receiver disclosed in Patent Document 1. In FIG. In the figure, 21 is a frequency synthesizer, 22 is a mixer that converts a modulated signal into an intermediate frequency (IF) signal using a local oscillation signal oscillated from the frequency synthesizer 21, and 23 is included in the IF signal output by the mixer 22. Bandpass filters for suppressing unnecessary frequency components, 24 and 25 are quadrature mixers for converting the modulation signal of the IF signal into I and Q baseband signals, 26 is a local oscillator for generating a local oscillation signal, and 27 is a local oscillator The 90 ° phase shifters 28 and 29 for shifting the phase of the local oscillation signal oscillated from the oscillator 26 by 90 ° suppress unnecessary frequency components contained in the baseband signals after frequency conversion by the quadrature mixers 24 and 25. A low-pass filter 30 is a demodulator.

  Next, the operation will be described. The modulation signal input to the receiver is frequency hopped, and the center frequency changes every moment. The mixer 22 converts the modulation signal into an IF signal using the fixed frequency local oscillation signal output from the frequency synthesizer 21. At this time, the IF signal is converted into a signal having a different center frequency corresponding to the frequency of the modulation signal switched by frequency hopping. These IF signals are input to a plurality of bandpass filters 23 having different center frequencies, and unnecessary frequency components are suppressed, and then output to the orthogonal mixers 24 and 25. In the quadrature mixers 24 and 25, the IF signal is converted into I and Q baseband signals using the local oscillation signal generated by the local oscillator 26. In this baseband signal, unnecessary frequency components are suppressed by the low-pass filters 28 and 29, and output to the demodulator 30. The demodulator 30 demodulates the I and Q baseband signals into data.

JP-A-6-21722

However, the prior art has the following problems.
In a conventional receiver, it is necessary to prepare a plurality of bandpass filters having different center frequencies in order to cope with modulated signals having different center frequencies by frequency hopping. In order to widen the frequency range for frequency hopping, a large number of band-pass filters are required, resulting in an increase in circuit scale. For this reason, it is difficult to perform frequency hopping over a wide band. If the frequency of the local oscillation signal output from the frequency synthesizer 21 is changed in accordance with the modulation signal to be frequency hopped, only one bandpass filter is required. Since it takes 100 μsec, it cannot cope with high-speed frequency hopping. The higher the frequency hopping, the higher the confidentiality of communication. However, the frequency synthesizer has a limitation on the high speed. Further, since a low-pass filter having a fixed frequency band is used for the baseband part, the baseband signal band cannot be varied.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a transceiver that is small in size, high in speed and high in accuracy, and capable of performing frequency hopping corresponding to various modulation methods. And

The transceiver according to the present invention is:
A direct digital synthesizer that generates a modulated signal and a carrier signal;
Transmitting means for transmitting the modulated signal generated by the direct digital synthesizer;
Receiving means for receiving a received signal;
A reception mixer for frequency-converting the received signal into a baseband signal or an intermediate frequency signal using the carrier signal generated by the direct digital synthesizer;
A sampling filter whose band is variable and suppresses unnecessary frequency components from the baseband signal or the intermediate frequency signal;
It is characterized by comprising.

  According to the present invention, by generating a modulation signal by a direct digital synthesizer (DDS), high-speed and high-accuracy frequency hopping can be realized by various modulation schemes. In addition, since the signal generated by DDS is used as a local oscillation signal of the receiving mixer of the receiving unit, a plurality of band pass filters with different center frequencies are not required, the frequency range for frequency hopping can be widened, and the circuit can be made compact Can be Since the received modulation signal is converted to a baseband frequency and a sampling filter is used as a filter to suppress unnecessary frequency components included in the frequency converted signal, the baseband frequency band can be varied. There is an effect that a signal of the modulation method can be transmitted and received.

Configuration diagram showing a transceiver according to Embodiment 1 of the present invention Configuration diagram showing a transceiver according to Embodiment 2 of the present invention Configuration diagram showing a transceiver according to Embodiment 3 of the present invention Configuration diagram showing a transceiver according to Embodiment 4 of the present invention Configuration diagram showing a conventional receiver

Embodiment 1 FIG.
1 is a block diagram showing a transceiver according to Embodiment 1 of the present invention. In the figure, 1 is a direct digital synthesizer (DDS) that generates a modulated signal and a carrier wave signal, 2 is a band-pass filter that suppresses unnecessary frequency components contained in the output of the DDS, and 3 is a power amplifier that amplifies the power of the transmission signal 4 is an antenna that is a transmission means, 5 is an antenna that is a reception means, 6 is a low-noise amplifier that amplifies the power of the received signal, 7 is a band-pass filter that suppresses unnecessary frequency components contained in the received signal, 9 is a reception mixer that converts the received signal into I and Q baseband signals, 10 and 11 are sampling filters that suppress unnecessary frequency components contained in the output signals from the orthogonal mixers 8 and 9, and 12 is a demodulator. Part.

Next, the operation will be described. When the transceiver of FIG. 1 operates as a transmitter, a direct digital synthesizer (DDS) 1 generates a frequency-hopped modulated signal. A direct digital synthesizer (DDS) can output a signal having an arbitrary phase by inputting a clock and phase data from the outside. By utilizing this, it is used as a circuit for generating a sine wave having an arbitrary frequency, a phase modulator, a frequency modulator, or the like. The DDS phase setting accuracy Δθ (degrees) is given by the following equation according to the bit length L of the phase data setting word.
Δθ = 360/2 ^L (1)
For example, if L = 16 bits, Δθ = 0.555 degrees, and very high-precision phase setting is possible.

The frequency setting accuracy ΔF is given by the following equation based on the frequency f _{CLK of} the clock input to the DDS and the bit length L of the setting word.
ΔF = f _CLK / 2 ^L (2)
For example, if f _CLK = 100 MHz and L = 16 bits, ΔF = 1.526 kHz, and the frequency can be varied in very fine steps.
Furthermore, in the DDS, a signal such as a sine wave is directly generated by digital processing, so that a signal having a predetermined frequency can be instantaneously output from phase data given in advance. That is, the time required for frequency setting at the time of frequency switching can be made much shorter than that of a PLL (Phase Locked Loop) synthesizer or the like.

In frequency hopping, communication is performed by sequentially switching the center frequency of a signal modulated by data to be communicated to a different frequency every predetermined time. For the modulation, for example, various methods such as amplitude modulation, phase modulation, frequency modulation, and a combination thereof can be used. In FIG. 1, since the frequency-hopped modulation signal is generated by the DDS1, it is only necessary to input set frequency data as external phase data, and frequency hopping with high frequency accuracy can be easily performed. In addition, since the time required for frequency switching can be very short, the time during which data transmission is impossible due to frequency instability at the time of frequency switching can be extremely reduced, and efficient data transmission can be achieved. Furthermore, it is possible to easily generate transmission signals of various modulation schemes and various modulation bands.
The modulation signal generated in this way is input to the band pass filter 2, and unnecessary frequency components generated in the DDS 1 are suppressed. This modulated signal is transmitted from the antenna 4 after the power is further amplified in the power amplifier 3.

Next, a description will be given of the case where the transceiver of FIG. 1 operates as a receiver.
The antenna 5 receives a frequency-hopped received signal. The received signal is amplified in power by the low noise amplifier 6, and unnecessary frequency components are suppressed by the band pass filter 7, and then divided into two and output to the orthogonal mixers 8 and 9, respectively. At the time of reception, the DDS 1 generates a carrier wave signal that is an unmodulated signal subjected to frequency hopping. This carrier signal is also divided into two and output to the quadrature mixers 8 and 9, respectively. At this time, although not shown in FIG. 1, a 90 ° phase shifter that shifts the phase of the carrier wave signal by 90 ° is arranged in one circuit after being divided into two as in FIG. The carrier signals input to 8 and 9 are 90 ° out of phase with each other. The quadrature mixers 8 and 9 frequency-convert the received signal from the bandpass filter 7 into I and Q baseband signals using the carrier signal input from the DDS 1 as a local oscillation signal.

  At the time of reception, a carrier wave signal that is a local oscillation signal of the quadrature mixers 8 and 9 is generated by the DDS 1, so that a carrier wave signal having high speed and high frequency accuracy can be obtained. Therefore, frequency conversion can also be performed with high accuracy. In addition, since the time required for frequency switching can be made very short, the time during which data reception is impossible due to frequency instability at the time of frequency switching can be greatly reduced, and efficient data reception can be achieved. Furthermore, carrier signals corresponding to various modulation schemes and various modulation bands can be easily generated.

  The I and Q baseband signals thus converted by the orthogonal mixers 8 and 9 are input to the sampling filters 10 and 11. Sampling filters 10 and 11 suppress unnecessary frequency components included in the I and Q baseband signals and output them to demodulator 12.

  The sampling filter is a variable variable filter using a switched capacitor technique. The sampling filter includes a plurality of capacitors (capacitors), and the capacitors are charged and discharged by periodically opening and closing a switch connected to the capacitors, and a current accompanying the movement of charges flows. By switching the capacitor that is charged and discharged by opening and closing the switch, the movement of the charge, that is, the current can be controlled to realize the filter characteristics. The pass and cut-off areas of the filter depend on the switching cycle of the switch, but this switching is controlled by the sampling clock input from the outside. Therefore, changing the sampling clock frequency also changes the switching cycle of the switch. The pass band and attenuation band of the filter can be made variable.

  Since the received signal includes noise and unnecessary waves, only the signal in the frequency band corresponding to the modulation band of the modulation method is left among the baseband signals output from the orthogonal mixers 8 and 9, and other unnecessary signals are left. It is necessary to suppress such frequency components. In the transmitter / receiver of FIG. 1, the sampling filters 10 and 11 are used for the baseband filter, so that the band of the filter can be varied by changing the frequency of the sampling clock. Therefore, it is possible to deal with modulated signals in various bands.

  The I and Q baseband signals in which unnecessary frequency components are suppressed are input to the demodulation unit 12 and demodulated into data or the like in the demodulation unit 12.

  As described above, in the present embodiment, since DDS1 is used for generating a modulation signal and a carrier signal, it is possible to perform high-speed and high-accuracy frequency hopping corresponding to various modulation schemes. Further, the signal generated by the DDS1 is used as a local oscillation signal of the quadrature mixers 8 and 9 of the receiving unit, and the received signal is converted to a baseband frequency, and a filter that suppresses unnecessary frequency components included in the frequency-converted signal. By using the sampling filters 10 and 11, the baseband frequency band can be varied, and reception and demodulation corresponding to various modulation methods can be performed at high speed and with high accuracy. Further, since a plurality of bandpass filters having different center frequencies used in the conventional receiver are not required, there is an effect that a small frequency hopping transceiver can be obtained.

  In the first embodiment, the transmitting antenna 4 that is a transmitting unit and the receiving antenna 5 that is a receiving unit are provided separately. However, these antennas can be used as a single transmission / reception antenna. In this case, a demultiplexer, a switch, or the like may be used to separate the modulated signal to be transmitted and the received signal.

  In the first embodiment, the antennas 4 and 5 are provided as the transmission unit and the reception unit. However, it is not always necessary to incorporate the antenna, and a connector for transmitting a transmission signal to a subsequent circuit, or a reception signal May be used as a connector for receiving the signal from the circuit in the previous stage, or a transmission / reception shared connector sharing these.

  Furthermore, in the first embodiment, the case where the local oscillation signal generated by the DDS 1 and input to the quadrature mixers 8 and 9 is set to the same frequency as the received signal and the baseband detection is performed is shown, but the present invention is not limited to this. The local oscillation signal generated by DDS1 can have a frequency different from that of the reception signal. In this case, signals output from the orthogonal mixers 8 and 9 are not baseband signals but intermediate frequency (IF) signals. In addition, the sampling filters 10 and 11 can use a band pass filter corresponding to the frequency of the IF signal instead of a low pass filter. Even in a band-pass sampling filter, the frequency band can be easily varied. Therefore, also in this case, the effect of the present embodiment can be obtained.

  In the first embodiment, the received signal is divided into two, and each of I and Q is detected by two orthogonal mixers 8 and 9. However, the present invention is not limited to this, and one receiving mixer is used. However, one sampling filter may be connected to it. Depending on the modulation method, it is not necessary to perform the detection of the I and Q2 systems, and the detection can be performed by a single detection circuit. In this case as well, the effect of this embodiment can be obtained. At this time, it is obvious that either baseband detection or IF detection may be used.

  Furthermore, although the case where communication using frequency hopping is performed has been described in the first embodiment, the present invention is not limited to this, and communication such as a method using FM-CW (Frequency Modulated-Continuous Wave) modulation, for example. Can also be done. In FM-CW, transmission and reception are performed using a modulation signal and a carrier wave signal whose frequency changes in a triangular wave shape with time. Mainly applied to radar systems. Also in this case, a signal with high frequency accuracy can be generated by the DDS 1 and unnecessary wave suppression corresponding to various bands can be performed by the sampling filters 10 and 11, so that the effect of the present embodiment can be similarly obtained.

Embodiment 2. FIG.
2 is a block diagram showing a transceiver according to Embodiment 2 of the present invention. In the figure, 13 is a mixer that converts the IF signal of the first intermediate frequency output from the DDS 1 into an RF (Radio Frequency) signal using the local oscillation signal output from the local oscillator 15, and 14 is the received RF signal. A mixer 15 for converting the frequency of the local oscillation signal output from the local oscillator 15 into an IF signal having a first intermediate frequency using the local oscillation signal, is a local oscillator. In addition, the same number is attached | subjected about the component equivalent to Embodiment 1 shown in FIG. 1, and description is abbreviate | omitted.

  Next, the operation will be described. At the time of transmission, the DDS 1 generates a modulation signal in the IF band, which is the first intermediate frequency, and outputs it to the mixer 13. In the mixer 13, the IF band signal generated by the DDS 1 is frequency-converted to an RF signal using the local oscillation signal output from the local oscillator 15. The frequency-converted RF signal is transmitted from the antenna 4 after unnecessary frequency components are suppressed in the band-pass filter 2 and further amplified in the power amplifier 3.

  At the time of reception, the received signal in the RF band received by the antenna 5 is amplified by the low noise amplifier 6, and unnecessary frequency components are suppressed by the band pass filter 7, and then output to the mixer 14. In the mixer 14, the received signal in the RF band output from the band pass filter 7 is frequency-converted to an IF band signal that is the first intermediate frequency using the local oscillation signal output from the local oscillator 15. This IF band signal is divided into two and output to quadrature mixers 8 and 9, respectively. During reception, the DDS 1 generates an IF band carrier signal and outputs it to the orthogonal mixers 8 and 9. At this time, the phases of the carrier signals input to the quadrature mixers 8 and 9 are shifted by 90 ° from each other by a 90 ° phase shifter (not shown). In the quadrature mixers 8 and 9, the IF band carrier signal input from the DDS1 is used as a local oscillation signal, and the received signal in the IF band is frequency-converted to the baseband frequencies of I and Q, and the sampling filters 10, 11 to output. In the sampling filters 10 and 11, unnecessary frequency components of the I and Q baseband frequency signals frequency-converted by the orthogonal mixers 8 and 9 are suppressed and output to the demodulator 12.

  In the second embodiment, similarly to the first embodiment, there is an effect that a small-sized transmitter / receiver capable of performing frequency hopping and the like corresponding to various modulation schemes with high speed and high accuracy can be obtained.

  Note that the frequency of the signal that can be generated by the DDS 1 is a relatively low frequency of about several hundred MHz. However, in the present embodiment, the mixer 13 uses the local oscillation signal from the local oscillator 15 to convert the frequency of the IF signal generated by the DDS 1 into an RF signal. Can be. Also, the received signal received by the antenna 5 is frequency-converted by the mixer 14 from the RF signal to an IF signal having the same frequency band as the carrier signal generated by the DDS 1 using the local oscillation signal from the local oscillator 15. The radio frequency received by the antenna 5 can be increased. As described above, the second embodiment has an effect of providing a transceiver that can be applied to high-frequency band communication such as microwave communication and millimeter wave communication.

  Further, in the second embodiment, even if the frequency of the IF band received signal that is the first intermediate frequency output from the mixer 14 during reception and the frequency of the IF band carrier signal that is the first intermediate frequency generated by the DDS 1 are changed. Good. In this case, the quadrature mixers 8 and 9 output the second intermediate frequency (IF) signal instead of the baseband frequency signal, but the sampling filters 10 and 11 are replaced with band-pass filters corresponding to the second intermediate frequency. The same effects as described above can be obtained.

Embodiment 3 FIG.
3 is a block diagram showing a transceiver according to Embodiment 3 of the present invention. In the figure, 16 is a first DDS for generating a modulation signal, and 17 is a second DDS for generating a carrier wave signal. In addition, the same number is attached | subjected about the component equivalent to Embodiment 1 shown in FIG. 1, and description is abbreviate | omitted.

  The present embodiment is different from the first embodiment in that a DDS 16 for generating a modulation signal and a DDS 17 for generating a carrier signal are separately provided. The modulation signal generated from the DDS 16 for generating the modulation signal is used for transmission, and the carrier signal generated from the DDS 17 for generating the carrier signal is used for reception. The timings of the DDS 16 and DDS 17 are controlled by a common clock.

  It is obvious that the same effect as in the first embodiment can be obtained in the third embodiment.

  Further, in the third embodiment, the modulation signal generation DDS 16 and the carrier signal generation DDS 17 are provided separately, so that different modulation signals and carrier signals can be generated simultaneously. At this time, the frequencies of the modulation signal and the carrier signal can be changed. Therefore, there is an effect that a transceiver capable of simultaneously transmitting a modulated signal and receiving a received signal can be obtained.

  In FIG. 3 which is the third embodiment, when all of the first DDS 16, the band pass filter 2, the power amplifier 3, and the antenna 4 related to the transmission function are eliminated, a receiver having only the reception function is obtained. . In such a receiver, since the DDS 17 for generating a carrier wave signal and the sampling filters 10 and 11 having variable bands are provided, the hopping is performed in a small size, at high speed and with high accuracy, and supports various modulation methods. There is an effect that a receiver capable of being obtained is obtained.

Embodiment 4 FIG.
FIG. 4 is a block diagram showing a transceiver according to Embodiment 4 of the present invention. Components corresponding to those in Embodiments 2 and 3 shown in FIGS. 2 and 3 are denoted by the same reference numerals and description thereof is omitted.
In the present embodiment, a first DDS 16 for generating a modulation signal and a second DDS 17 for generating a carrier signal are provided separately from the second embodiment.

  In the fourth embodiment, it is obvious that there is an effect that a transmitter / receiver that can cope with a high frequency can be obtained as in the second embodiment.

  Further, in the fourth embodiment, the DDS 16 for generating the modulation signal and the DDS 17 for generating the carrier signal are separately provided, so that a transceiver capable of simultaneously transmitting the modulation signal and receiving the reception signal is obtained. effective.

  In FIG. 4 which is the fourth embodiment, when all of the first DDS 16, the mixer 13, the band pass filter 2, the power amplifier 3 and the antenna 4 related to the transmission function are eliminated, the receiver having only the reception function. Is obtained. Even in such a receiver, there is an effect that a receiver that can deal with a high-frequency received signal and that is small, high-speed, high-precision, and capable of performing frequency hopping corresponding to various modulation schemes can be obtained. .

DESCRIPTION OF SYMBOLS 1 Direct digital synthesizer, 2 Bandpass filter, 3 Power amplifier, 4, 5 Antenna, 6 Low noise amplifier, 7 Bandpass filter, 8, 9 Quadrature mixer, 10, 11 Sampling filter, 12 Demodulator, 13, 14 Mixer, 15 Local oscillator, 16, 17 Direct digital synthesizer, 21 Frequency synthesizer, 22 Mixer, 23 Band pass filter, 24, 25 Quadrature mixer, 26 Local oscillator, 27 90 ° phase shifter, 28, 29 Low pass filter, 30 Demodulation Part

Claims (9)

A direct digital synthesizer that generates a modulated signal and a carrier signal;
Transmitting means for transmitting the modulated signal generated by the direct digital synthesizer;
Receiving means for receiving a received signal;
A reception mixer for frequency-converting the received signal into a baseband signal or an intermediate frequency signal using the carrier signal generated by the direct digital synthesizer;
A sampling filter whose band is variable and suppresses unnecessary frequency components from the baseband signal or the intermediate frequency signal;
A transmitter / receiver characterized by comprising: A first direct digital synthesizer for generating a modulated signal;
A second direct digital synthesizer that generates a carrier signal;
Transmitting means for transmitting the modulated signal generated by the first direct digital synthesizer;
Receiving means for receiving a received signal;
A reception mixer for frequency-converting the received signal into a baseband signal or an intermediate frequency signal using the carrier wave signal generated by the second direct digital synthesizer;
A sampling filter whose band is variable and suppresses unnecessary frequency components from the baseband signal or the intermediate frequency signal;
A transmitter / receiver characterized by comprising: A local oscillator for generating a local oscillation signal;
A mixer for frequency-converting the modulated signal from a first intermediate frequency band to a radio frequency band using the local oscillation signal;
A mixer for frequency-converting the received signal from a radio frequency band to a first intermediate frequency band using the local oscillation signal;
The transceiver according to claim 1 or 2, further comprising:   The transceiver according to any one of claims 1 to 3, wherein the received signal is a frequency-hopped signal.   4. The transceiver according to claim 1, wherein the received signal is an FM-CW modulated signal. Receiving means for receiving a received signal;
A direct digital synthesizer that generates a carrier signal;
A reception mixer for frequency-converting the received signal into a baseband signal or an intermediate frequency signal using the carrier signal generated by the direct digital synthesizer;
A sampling filter whose band is variable and suppresses unnecessary frequency components from the baseband signal or the intermediate frequency signal;
A receiver comprising: A local oscillator for generating a local oscillation signal;
A mixer for frequency-converting the received signal from a radio frequency band to a first intermediate frequency band using the local oscillation signal;
The receiver according to claim 6, further comprising:   The receiver according to claim 6 or 7, wherein the received signal is a frequency hopped signal.   The receiver according to claim 6 or 7, wherein the received signal is an FM-CW modulated signal.

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