JPH104437A - Digital signal transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a situation where an error occurs in a carrier digital signal and which results from the feedback of a sent carrier digital signal to a local oscillating part and also to fuly operate with only a single local oscillating part by applying quadrature modulation to a carrier signal which has a prescribed frequency by a base band signal. SOLUTION: A quadrature modulation part 21 forms a carrier digital signal SDI with a dividing signal SLD as a carrier signal by applying quadrature modulation to the carrier signal by a digital base band signal DI from a digital signal generation part 11. A frequency transformation part 25 undergoes frequency transformation by using a 2nd distributing signal about the signal DSI through an LPF, from which the part 25 acquires an output carrier digital signal SCI. The signal SCI which is acquired from the part 25 is amplified by an amplifier, supplied to a sending antenna 15 and transmitted by radio after an image frequency component, etc., is eliminated by a BPF.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier digital signal obtained by subjecting a carrier signal to quadrature modulation by a digital baseband signal to form a carrier digital signal, and subjecting the carrier digital signal or the carrier digital signal to frequency conversion. The present invention relates to a digital signal transmission device for transmitting a signal wirelessly.

[0002]

2. Description of the Related Art When radio transmission of a digital information signal is performed, a digital information signal to be transmitted is used as a baseband signal, and a carrier signal having a predetermined frequency is subjected to quadrature modulation by the baseband signal. Generally, a technique of wirelessly transmitting the obtained carrier digital signal through an antenna is used. The quadrature modulation by the baseband signal basically forms first and second carrier signals having a mutual phase difference of 90 degrees based on the carrier signal having a predetermined frequency, and forms the first and second carrier signals. This is performed by modulating each of the two carrier signals with a baseband signal and combining the first and second modulated output signals obtained thereby individually to form a modulated output signal to be a carrier digital signal.

FIG. 8 shows an example of a digital signal transmitting apparatus having a basic configuration for wirelessly transmitting a digital information signal as described above. In the example shown in FIG. 8, a digital baseband signal DI which is a digital information signal to be transmitted, which is transmitted from the digital signal generator 11, and a predetermined frequency which is transmitted from the local oscillator 12 are provided. Oscillation output signal S which is the fundamental wave component
L are supplied to the quadrature modulator 13. Quadrature modulator 13
, The oscillation output signal SL is a carrier signal, the carrier signal is subjected to quadrature modulation by the digital baseband signal DI, and the output carrier digital signal SCI
Is formed. And the output carrier digital signal SCI
Is amplified by the amplifying unit 14, supplied to the transmission antenna 15, and wirelessly transmitted through the transmission antenna 15.

FIG. 9 shows an example of a digital signal transmitting apparatus having a configuration different from the configuration shown in FIG. 8 for wirelessly transmitting a digital information signal as described above. In the example shown in FIG. 9, a digital baseband signal DI, which is a digital information signal to be transmitted, transmitted from the digital signal generator 11 and a predetermined frequency transmitted from the local oscillator 16 are provided. The oscillation output signal SLA, which is the fundamental wave component,
Supplied to In the quadrature modulator 17, the oscillation output signal SLA is used as a carrier signal, and the carrier signal is subjected to quadrature modulation by the digital baseband signal DI to form a carrier digital signal SDI.

[0005] The carrier digital signal SDI obtained from the quadrature modulator 17 and a local oscillator 1 different from the local oscillator 16.
8 and an oscillation output signal SLB, which is a fundamental wave component having a predetermined frequency, is supplied to a frequency conversion unit 19, where the carrier digital signal SDI is converted into a frequency by the oscillation output signal SLB. The output carrier digital signal SCI is formed. The frequency conversion for such a carrier digital signal SDI is:
For example, the resulting output carrier digital signal S
This is performed so that the carrier frequency of CI is the difference frequency between the carrier frequency of carrier digital signal SDI and the frequency of oscillation output signal SLB. Then, the output carrier digital signal SCI is amplified by the amplifying unit 14, supplied to the transmission antenna 15, and wirelessly transmitted through the transmission antenna 15.

[0006]

In the example of the digital signal transmitting apparatus shown in FIG. 8, the output carrier digital signal S transmitted wirelessly through the transmitting antenna 15 is used.
CI indicates that the carrier frequency is the frequency of the oscillation output signal SL transmitted from the local oscillation unit 12, and therefore the local oscillation unit 1
2 is equal to the fundamental oscillation frequency. Then, a part of the output carrier digital signal SCI wirelessly transmitted through the transmission antenna 15 is fed back to the local oscillation unit 12 through a feedback path FBL as shown by a dashed line in FIG. When the degree of coupling of the feedback path FBL changes, the phase of the oscillation output signal SL sent from the local oscillator 12 is caused by the fact that the carrier frequency of the output carrier digital signal SCI is equal to the fundamental oscillation frequency of the local oscillator 12. Changes with the change in the coupling degree of the return path FBL. Such a phase change of the oscillation output signal SL affects the quadrature modulation of the oscillation output signal SL in the quadrature modulator 13 by the digital baseband signal DI as a carrier signal, and the output carrier digital signal obtained from the quadrature modulator 13 An error will occur in the SCI.

In the example of the digital signal transmitting apparatus shown in FIG. 9 described above, the output carrier digital signal SCI wirelessly transmitted through the transmitting antenna 15 has its carrier frequency transmitted from the local oscillator 16. The frequency of the oscillation output signal SLA, which is different from the fundamental oscillation frequency of the local oscillator 16, and the frequency of the oscillation output signal SLB transmitted from the local oscillator 18, and therefore, is different from the fundamental oscillation frequency of the local oscillator 18. Will be. Under such circumstances, a part of the output carrier digital signal SCI wirelessly transmitted through the transmission antenna 15 is fed back to the local oscillation unit 16 through a feedback path FBLA as shown by a dashed line in FIG. 9, the signal is fed back to the local oscillator 18 through a feedback path FBLB as indicated by a two-dot chain line.
Even if the coupling degree of BLA or return path FBLB changes,
Since the carrier frequency of the output carrier digital signal SCI is different from both the fundamental oscillation frequency of the local oscillator 16 and the fundamental oscillation frequency of the local oscillator 18, the phase of the oscillation output signal SLA sent from the local oscillator 16 or the local oscillator It is unlikely that the phase of the oscillation output signal SLB transmitted from 18 changes with a change in the feedback path FBLA or the degree of coupling of the feedback path FBLB.

[0009] However, in the example of the digital signal transmitting apparatus shown in FIG. 9, due to the nonlinearity of the frequency conversion unit 19,
In addition to the output carrier digital signal SCI, the quadrature modulator 1
7 and a plurality of spurious signals by frequency conversion performed between the carrier digital signal SDI from the local oscillator 18 and each of a plurality of harmonic components generated in addition to the oscillation output signal SLB from the local oscillator 18 are output from the output carrier digital signal SCI. It will be formed as having a frequency near the carrier frequency. FIG. 10 (horizontal axis: frequency, vertical axis: level)
An example of a spurious signal generation state on the output side of the frequency conversion unit 19 is shown. In the example shown in FIG. 10, for example, for an output carrier digital signal SCI having a carrier frequency of 940.0 MHz, spurious signals SS1 to SS3 having a frequency lower than the frequency of the output carrier digital signal SCI, and the like. Output carrier digital signal S
Spurious signal S having a frequency higher than the frequency of CI
Many spurious signals such as S4 to SS6 are generated.

Such an output carrier digital signal SCI
Is also wirelessly transmitted together with the output carrier digital signal SCI via the transmission antenna 15, which adversely affects the receiving side receiving the output carrier digital signal SCI.

Further, in the example of the digital signal transmitting apparatus shown in FIG. 9, two local oscillators 16 and 18 are required, thereby increasing the overall size, increasing the weight,
There is also a problem that power consumption is increased.

In view of the above, the present invention provides a digital information signal to be transmitted as a baseband signal, performing quadrature modulation by a baseband signal on a carrier signal having a predetermined frequency, and obtaining the resulting carrier digital signal. When performing radio transmission directly or by performing frequency conversion, it is possible to avoid a situation where an error occurs in the transmitted carrier digital signal due to feedback of a part of the transmitted carrier digital signal to the local oscillator. , And the local oscillator is 1
In addition, the generation of a spurious signal having a frequency near the carrier frequency associated with the transmitted carrier digital signal can be avoided, and the local oscillator forms a phase locked loop (PLL). In this case, there is provided a digital signal transmitting apparatus capable of shortening the frequency hopping time and improving the reference leak characteristic.

[0012]

According to a first aspect of the present invention, there is provided a digital signal transmitting unit for transmitting a digital baseband signal, and a local unit for transmitting an oscillation output signal having a predetermined frequency. An oscillation unit, a signal distribution unit that distributes an oscillation output signal as a first distribution signal and a second distribution signal, a frequency division unit that divides the first distribution signal to obtain a frequency division signal, and a frequency division signal. A quadrature modulator for obtaining a carrier digital signal by performing quadrature modulation with a digital baseband signal on the carrier signal as a carrier signal, and obtaining an output carrier digital signal by performing frequency conversion using the second distribution signal on the carrier digital signal It comprises a frequency converter and a wireless transmitter for wirelessly transmitting the output carrier digital signal.

In a second aspect of the digital signal transmitting apparatus according to the present invention, a digital signal generator for transmitting a digital baseband signal, a local oscillator for transmitting an oscillation output signal having a predetermined frequency, A signal distribution unit that distributes the oscillation output signal as a first distribution signal and a second distribution signal; a frequency division unit that divides the first distribution signal to obtain a frequency-divided signal; A frequency conversion unit that performs frequency conversion using a distribution signal to obtain a carrier signal; a quadrature modulation unit that performs orthogonal modulation on a carrier signal by a digital baseband signal to obtain an output carrier digital signal; And a wireless transmission unit for transmitting.

In each of the first and second embodiments of the digital signal transmitting apparatus according to the present invention, for example, the local oscillator forms a PLL. In the first aspect of the digital signal transmitting apparatus according to the present invention, for example, the frequency conversion unit subtracts the carrier frequency of the output carrier digital signal from the frequency of the second distribution signal by subtracting the carrier frequency of the carrier digital signal. In the second aspect of the digital signal transmitting apparatus according to the present invention, for example, the frequency conversion unit converts the frequency of the carrier signal to the frequency of the second distribution signal. From the frequency of the frequency-divided signal from the frequency divider.

In the first aspect of the digital signal transmitting apparatus according to the present invention, the oscillation output signal from the local oscillation section is provided under the condition that one local oscillation section is provided. The signal is divided into a first distribution signal and a second distribution signal by a distributor. Then, the frequency division unit adds 1 / N to the first distribution signal, for example, as a power of 2 of 4 or more.
The carrier signal is formed by dividing by N.
In the quadrature modulator, the carrier signal is subjected to quadrature modulation by a digital baseband signal to form a carrier digital signal. Further, in the frequency conversion unit, a second digital signal obtained from the signal distribution unit for the carrier digital signal is obtained.
The frequency conversion is performed using the distribution signal of the above, and an output carrier digital signal is formed, which is wirelessly transmitted through the wireless transmission unit.

Therefore, the carrier frequency of the output carrier digital signal is different from the frequency of the oscillation output signal transmitted from the local oscillation section, and therefore, the fundamental oscillation frequency of the local oscillation section. 1 for the first distribution signal
The carrier signal is formed by performing the 分 frequency division, and the frequency converter sets the carrier frequency of the output carrier digital signal to a frequency obtained by subtracting the carrier frequency of the carrier digital signal from the frequency of the second distribution signal. In this case, the carrier frequency of the output carrier digital signal is 3/4 times the frequency of the oscillation output signal sent from the local oscillator.

Under such a circumstance, a part of the output carrier digital signal wirelessly transmitted through the wireless transmission unit is fed back to the local oscillation unit. At this time, the coupling degree of the feedback path from the wireless transmission unit to the local oscillation unit is adjusted. Changes, the carrier frequency of the output carrier digital signal differs from the fundamental oscillation frequency of the local oscillator, so the phase of the oscillation output signal sent from the local oscillator changes with the change in the coupling degree of the feedback path. This is unlikely to occur, thus avoiding errors in the output carrier digital signal.

Further, the carrier frequency of the output carrier digital signal is set to 3/4 times the frequency of the oscillation output signal transmitted from the local oscillator, so that
The spurious signal formed with the output carrier digital signal has the same frequency as the carrier frequency of the output carrier digital signal, thereby avoiding the generation of spurious signals having a frequency near the carrier frequency of the output carrier digital signal. Note that a spurious signal having the same frequency as the carrier frequency of the output carrier digital signal is easily suppressed by improving the linearity of the frequency conversion unit.

Further, when the carrier frequency of the output carrier digital signal is changed at a predetermined frequency interval of, for example, 25 KHz, the fundamental oscillation frequency of the local oscillator is changed at a predetermined frequency interval. That is, when the local oscillator forms a PLL, the phase comparison frequency in the PLL can be higher than the frequency corresponding to the carrier frequency interval of the output carrier digital signal. As a result, the frequency hopping time of the PLL formed by the oscillation section can be reduced and the reference leak characteristics can be improved.

Also in the second aspect of the digital signal transmitting apparatus according to the present invention, the oscillation signal output from the local oscillation section is supplied to the first distribution signal by the signal distribution section, provided that one local oscillation section is provided. And a second distribution signal. Then, the frequency divider converts the first divided signal into, for example,
Frequency division is performed by dividing 1 / N by dividing N by 4 or a power of 2 to form a frequency-divided signal, and the frequency converter converts the frequency-divided signal into a second distribution obtained from the signal distributor. Frequency conversion is performed using the signal to form a carrier signal. Further, the carrier signal is subjected to quadrature modulation by a digital baseband signal in the quadrature modulator to form an output carrier digital signal, which is wirelessly transmitted through the wireless transmitter.

Therefore, the carrier frequency of the output carrier digital signal is different from the frequency of the oscillation output signal transmitted from the local oscillation section, and therefore, the fundamental oscillation frequency of the local oscillation section. 1 for the first distribution signal
When the 信号 frequency division is performed to form a frequency-divided signal, and the frequency converter sets the frequency of the carrier signal to a frequency obtained by subtracting the carrier frequency of the frequency-divided signal from the frequency of the second distribution signal, The carrier frequency of the output carrier digital signal, that is, the frequency of the carrier signal is 3/4 times the frequency of the oscillation output signal transmitted from the local oscillator.

Under such a circumstance, a part of the output carrier digital signal wirelessly transmitted through the wireless transmission unit is fed back to the local oscillation unit, and at this time, the coupling degree of the feedback path from the wireless transmission unit to the local oscillation unit Changes, the carrier frequency of the output carrier digital signal differs from the fundamental oscillation frequency of the local oscillator, so the phase of the oscillation output signal sent from the local oscillator changes with the change in the coupling degree of the feedback path. This is unlikely to occur, thus avoiding errors in the output carrier digital signal.

Further, the frequency of the carrier signal is set to ／ times the frequency of the oscillation output signal transmitted from the local oscillation section, so that the spurious signal formed together with the carrier signal in the frequency conversion section becomes And the generation of a spurious signal having a frequency near the frequency of the carrier signal is avoided. Note that a spurious signal having the same frequency as the frequency of the carrier signal is easily suppressed by improving the linearity of the frequency conversion unit.

Further, when the carrier frequency of the output carrier digital signal is changed at a predetermined frequency interval of, for example, 25 KHz, the fundamental oscillation frequency of the local oscillator is changed at a predetermined frequency interval. That is, when the local oscillator forms a PLL, the phase comparison frequency in the PLL can be higher than the frequency corresponding to the carrier frequency interval of the output carrier digital signal. As a result, the frequency hopping time of the PLL formed by the oscillation section can be reduced and the reference leak characteristics can be improved.

In each of the first and second aspects of the digital signal transmitting apparatus according to the present invention as described above, only one local oscillator is required, and
Compared to a digital signal transmission device requiring two local oscillators as shown in FIG. 9, the overall size, weight and power consumption can be reduced.

[0026]

FIG. 1 shows an example of a digital signal transmitting apparatus according to the present invention. In the example shown in FIG. 1, a digital baseband signal DI, which is a digital information signal to be transmitted and is transmitted from the digital signal generator 11, is supplied to the quadrature modulator 21. An oscillation output signal SL, which is a fundamental wave component having a predetermined frequency and transmitted from the local oscillation unit 12, is supplied to the signal distribution unit 22, and the signal distribution unit 22 divides the oscillation output signal SL into a first distribution signal. The signal is distributed as a signal and a second distribution signal. The frequency range of the oscillation output signal SL is, for example, 1233.366M.
Hz to 1274.634 MHz.

The first distribution signal (oscillation output signal SL) from the signal distribution unit 22 is supplied to the frequency division unit 23,
3 performs 1 / N frequency division, for example, 1/4 frequency division, on the first distributed signal, where N is a power of 2 which is 4 or more, to obtain 1/4 of the frequency of the oscillation output signal SL. A frequency-divided signal SLD having a corresponding frequency is formed. The frequency-divided signal SLD obtained from the frequency divider 23 is supplied to the quadrature modulator 21.

The quadrature modulator 21 forms the carrier digital signal SDI by using the frequency-divided signal SLD as a carrier signal and subjecting the carrier signal to quadrature modulation using the digital baseband signal DI from the digital signal generator 11. The carrier digital signal SDI obtained from the quadrature modulator 21 is obtained by removing a harmonic component through a low-pass filter (LPF) 24 and supplied to a frequency converter 25. The range of the carrier frequency of the carrier digital signal SDI is, for example, 308.341 MHz to 318.65.
9 MHz.

The second distribution signal (oscillation output signal SL) from the signal distribution unit 22 is also supplied to the frequency conversion unit 25. Then, the frequency converter 25 performs frequency conversion on the carrier digital signal SDI passed through the LPF 24 using the second distribution signal, thereby obtaining an output carrier digital signal SCI. Such a carrier digital signal SDI
The frequency conversion for the output carrier digital signal SC
The carrier frequency of I is changed to a second distribution signal (oscillation output signal S
The frequency is obtained by subtracting the carrier frequency of the carrier digital signal SDI from the frequency L). The range of the carrier frequency of the output carrier digital signal SCI is, for example, 925.025 MHz to 955.975M.
Hz.

The output carrier digital signal SCI obtained from the frequency conversion unit 25 is converted to a band pass filter (BPF) 2
After removal of image frequency components etc. through 6,
The signal is amplified by the amplifier 14, supplied to the transmission antenna 15, and transmitted wirelessly through the transmission antenna 15. Here, the BPF 26, the amplification unit 14, and the transmission antenna 15
It forms a wireless transmitter for wirelessly transmitting the output carrier digital signal SCI obtained from the frequency converter 25.

Under such circumstances, the local oscillation unit 12 forms, for example, a PLL as shown in FIG. In the PLL shown in FIG. 2, for example, a reference oscillation output signal SO obtained from a reference oscillation unit 31 formed by a crystal oscillator is supplied to a frequency dividing unit 32. In the frequency divider 32, the reference oscillation output signal SO is frequency-divided with a predetermined frequency division ratio to form a reference signal SOD, which is supplied to one of a pair of input terminals of the phase comparator 33. Is done. The other of the pair of input terminals of the phase comparator 33 has a frequency-divided output signal SL from the variable frequency divider 35.
V is also supplied.

In the phase comparing section 33, the variable frequency dividing section 3
The phase comparison of the frequency-divided output signal SLV from 5 with respect to the reference signal SOD obtained from the frequency divider 32 is performed, and the comparison output signal SPD representing the phase comparison result is obtained. The comparison output signal SPD is integrated in the filter unit 34, is supplied as a DC control voltage SDD, and is supplied to a voltage control oscillator (VCO) 36.

The VCO 36 performs an oscillating operation at a basic oscillation frequency according to the DC control voltage SDD, and generates an oscillation output signal SL. The oscillation output signal SL emitted from the VCO 36 is supplied to the variable frequency dividing section 35, subjected to frequency division in the variable frequency dividing section 35, and led out to the oscillation output terminal 37. The variable frequency divider 35 sets a frequency division ratio for the oscillation output signal SL generated from the VCO 36 in accordance with the control signal CC, and performs frequency division on the oscillation output signal SL with the set frequency division ratio. Signal SL
The frequency of V is made to match the frequency of the reference signal SOD.

In this manner, the frequency dividing ratio of the variable frequency dividing section 35 to the oscillation output signal SL generated from the VCO 36 is set according to the control signal CC.
The oscillation output signal SL derived to the oscillation output terminal 37 is changed stepwise at predetermined frequency intervals. For example, the frequency range of the oscillation output signal SL derived to the oscillation output terminal 37 is 1233.366 MHz. ~ 1274.6
34 MHz.

In such a PLL, the variable frequency divider 35
The frequency hopping time, which is the time from when the frequency division ratio is changed to when the basic oscillation frequency of the VCO 36 falls within a predetermined range, is short, and the DC control voltage SDD
The reference signal component from the frequency divider 32 is mixed into the VCO 3
It is desired that reference leakage, which is a phenomenon in which a reference signal component and its harmonic component appear in the oscillation output signal SL emitted from the reference signal 6, is small. Such shortening of the frequency hopping time and reduction of the reference leak are achieved by reducing the frequency of the frequency-divided output signal SLV and the frequency of the reference signal SOD, which are compared in the phase comparator 33, by using the output carrier digital signal SCI obtained from the frequency converter 25. This is achieved by making the frequency higher than the frequency corresponding to the frequency interval in.

The quadrature modulating section 21 has a pair of multiplying sections 42 and 43, to which the digital baseband signal DI from the digital signal generating section 11 is supplied through a terminal 41, as shown in a specific configuration example shown in FIG. A 90-degree phase shifter 45 to which the frequency-divided signal SLD from the frequency divider 23 is supplied through a terminal 44, a signal combiner 46 connected to the output terminals of the pair of multipliers 42 and 43, and a signal combiner 46. It is configured to include the terminal 47 drawn out. 90 degree phase shifter 4
5 is a first carrier signal SL having a 90 ° mutual phase difference based on the frequency-divided signal SLD as a carrier signal.
DI and a second carrier signal SLDQ are formed and supplied to a pair of multipliers 42 and 43, respectively.

The multiplying section 42 controls the first carrier signal SLDI
And a digital baseband signal DI to form a first multiplied output signal SDDI.
Performs the multiplication of the second carrier signal SLDQ and the digital baseband signal DI to generate a second multiplied output signal SDD.
Form Q. Then, the first multiplication output signal SDDI obtained from the multiplication unit 42 and the second multiplication output signal SDDQ obtained from the multiplication unit 43 are synthesized in the signal synthesis unit 46 to form the carrier digital signal SDI. It is led out to the terminal 47.

The 90-degree phase shifter 45 in the specific configuration example of the quadrature modulator 21 shown in FIG. 3 is, for example, as shown in FIG.
Flip-flop (D-F) formed by a pair of latch units 51 and 52 connected to the frequency doubling unit 50 and the output side of the frequency doubling unit 50.
F) 53 and a pair of terminals 54 and 55 drawn out from the D-FF 53.

The frequency doubling section 50 receives, for example, the signal A in the waveform diagram (horizontal axis: time) of FIG.
The pulse duty is 5 as shown in FIG.
A frequency-divided signal SLD, which is a pulse train signal of 0%, is supplied, and based on the frequency-divided signal SLD, as shown in FIGS. 5B and 5C, opposite polarities having twice the frequency of the frequency-divided signal SLD. Pulse train signal SX and inverted pulse train signal-
SX is formed. The pulse train signal SX and the inverted pulse train signal -SX are supplied to the latch units 51 and 52 forming the D-FF 53 as a clock signal and an inverted clock signal, respectively.

In the latch units 51 and 52, the output terminal Q1 and the inverted output terminal -Q1 of the latch unit 51 are connected to the input terminal D2 and the inverted input terminal -D2 of the latch unit 52, respectively. End Q
2 and the inverted output terminal -Q2 are connected to the inverted input terminal -D1 and the input terminal D1 of the latch unit 51, respectively. As a result, a pulse train signal S serving as a clock signal and an inverted clock signal as shown in D and E of FIG.
X and 1/2 of each frequency of inverted pulse train signal -SX
, And a pulse train signal SQ1 and an inverted pulse train signal -SQ1 having opposite polarities are obtained, respectively. Further, from the output terminal Q2 and the inverted output terminal -Q2 of the latch section 52, they are shown in FIGS. The pulse train signal S
A pulse train signal SQ having a phase difference of 90 degrees with respect to Q1
2 and an inverted pulse train signal -SQ2 having a phase difference of 90 degrees with respect to the inverted pulse train signal -SQ1.

The inverted pulse train signal -SQ1 obtained from the inverted output terminal -Q1 of the latch unit 51, and
Obtained from the inverted output terminal -Q2 of the latch unit 52,
An inverted pulse train signal -SQ2 having a phase difference of 90 degrees with respect to the inverted pulse train signal -SQ1 is respectively derived to a pair of terminals 54 and 55, and the first carrier wave has a mutual phase difference of 90 degrees. The signal SLDI and the second carrier signal SLDQ are used.

Further, in the example shown in FIG. 1, the portion including the quadrature modulation section 21 and the frequency dividing section 23, which are surrounded by a dashed line, may be replaced by the configuration shown in FIG. In the configuration shown in FIG.
Is supplied with the digital baseband signal DI from the digital signal generator 11 and the terminal 62 is supplied with the first distribution signal (oscillation output signal SL) from the signal distributor 22. Then, the digital baseband signal DI supplied to the terminal 61 is
And 64 respectively. Further, the first distribution signal supplied to the terminal 62 is supplied to the frequency dividing section 65 which is the first stage of the two-stage frequency dividing section. And divide the frequency by 1/2 to generate the oscillation output signal SL.
Divided signal S having a frequency corresponding to half the frequency of
Form LE. This frequency-divided signal SLE is a pulse train signal with a pulse duty of 50%.

The divided signal SLE obtained from the dividing section 65
Is supplied to a frequency divider 66, which is the second of the two stages of frequency dividers. The frequency divider 66 further divides the frequency of the frequency-divided signal SLE by １ ／, whereby Forms a pair of frequency-divided signals having a frequency corresponding to 1/4 of the frequency of the oscillation output signal SL and having a mutual phase difference of 90 degrees, and converts them into a first carrier signal SLEI and a second carrier signal. Transmit as SLEQ. Then, the first carrier signal SLEI and the second carrier signal SLEQ are supplied to multipliers 63 and 64, respectively.

The multiplying unit 63 outputs the first carrier signal SLEI
And the digital baseband signal DI to form a first multiplied output signal SDEI.
Performs the multiplication of the second carrier signal SLEQ and the digital baseband signal DI to generate a second multiplied output signal SDE.
Form Q. Then, the first multiplication output signal SDEI obtained from the multiplication unit 63 and the second multiplication output signal SDEC obtained from the multiplication unit 64 are synthesized in the signal synthesis unit 67 to form the carrier digital signal SDI. It is led out to the terminal 68. Under such circumstances, the multiplier 63 and the multiplier 64 substantially form a quadrature modulator.

In the example shown in FIG. 1 as described above, only one local oscillating section 12 is required, and therefore, two local oscillating sections as shown in FIG. 9 are required. Compared to digital signal transmitters
Thus, weight and power consumption can be reduced.

The carrier frequency of the output carrier digital signal SCI is 3/4 times the frequency of the oscillation output signal SL sent from the local oscillation unit 12, that is, the fundamental oscillation frequency of the local oscillation unit 12. Therefore, a part of the output carrier digital signal SCI wirelessly transmitted through the transmission antenna 15 is fed back to the local oscillation unit 12, and at this time, even if the coupling degree of the feedback path from the transmission antenna 15 to the local oscillation unit 12 changes. Since the carrier frequency of the output carrier digital signal SCI is different from the fundamental oscillation frequency of the local oscillation unit 12, the phase of the oscillation output signal SL sent from the local oscillation unit 12 changes with the change in the coupling degree of the feedback path. This is unlikely to occur, so that an error in the carrier digital signal SDI and in the output carrier digital signal SCI is avoided.

Further, since the carrier frequency of output carrier digital signal SCI is set to 倍 times the frequency of oscillation output signal SL sent from local oscillation section 12, output carrier digital signal SCI The resulting spurious signal has the same frequency as the carrier frequency of the output carrier digital signal SCI, and generation of a spurious signal having a frequency near the carrier frequency of the output carrier digital signal SCI is avoided.
Note that the spurious signal having the same frequency as the carrier frequency of the output carrier digital signal SCI is
Can be easily suppressed by improving the linearity of

Further, the carrier frequency of the output carrier digital signal SCI is, for example, 925.025 MHz to 95 MHz.
When the frequency is changed at a frequency interval of 25 KHz within the range of 5.975 MHz, the basic oscillation frequency of the local oscillation unit 12 is changed at a predetermined frequency interval. P as shown in
In the case of forming the LL, the phase comparison frequency in the PLL can be set to a frequency higher than the frequency corresponding to the carrier frequency interval of the output carrier digital signal SCI. This shortens the frequency hopping time and improves the reference leak characteristics.

FIG. 7 shows another example of the digital signal transmitting apparatus according to the present invention. In the example shown in FIG. 7, a digital baseband signal DI, which is a digital information signal to be transmitted and is transmitted from the digital signal generator 11, is supplied to the quadrature modulator 73. An oscillation output signal SL, which is a fundamental wave component having a predetermined frequency and transmitted from the local oscillation unit 12, is supplied to the signal distribution unit 22, and the signal distribution unit 22 divides the oscillation output signal SL into a first distribution signal. The signal is distributed as a signal and a second distribution signal. The frequency range of the oscillation output signal SL is, for example, 1233.366 MHz.
１２1274.634 MHz.

The first distribution signal (oscillation output signal SL) from the signal distribution unit 22 is supplied to the frequency division unit 23,
3 performs 1 / N frequency division, for example, 1/4 frequency division, on the first distributed signal, where N is a power of 2 which is 4 or more, to obtain 1/4 of the frequency of the oscillation output signal SL. A frequency-divided signal SLD having a corresponding frequency is formed. The frequency-divided signal SLD obtained from the frequency divider 23 is supplied to the frequency converter 71.

The frequency conversion section 71 performs frequency conversion on the frequency-divided signal SLD using the second distribution signal, and thereby obtains a carrier signal SLC. Such a divided signal SLD
Is performed by setting the frequency of the carrier signal SLC to a frequency obtained by subtracting the frequency of the frequency-divided signal SLD from the frequency of the second distribution signal (oscillation output signal SL). The frequency range of the carrier signal SLC is
For example, 925.025 MHz to 955.975 MHz
It is said.

The carrier signal SLC obtained from the frequency converter 71 is supplied to the quadrature modulator 73 through the BPF 72. The quadrature modulator 73 converts the carrier signal SLC into the digital baseband signal D from the digital signal generator 11.
The output carrier digital signal SCI is formed by performing quadrature modulation by I. The output carrier digital signal SCI obtained from the quadrature modulator 73 passes through the BPF 26, is amplified by the amplifier 14, is supplied to the transmission antenna 15, and is wirelessly transmitted through the transmission antenna 15.
Here, the BPF 26, the amplification unit 14, and the transmission antenna 15
Form a wireless transmission unit for wirelessly transmitting the output carrier digital signal SCI obtained from the quadrature modulation unit 73.

In the example shown in FIG. 7,
The local oscillation unit 12 includes, for example, a PL as shown in FIG.
L, and the quadrature modulator 73 takes a specific configuration example as shown in FIG. However, when the quadrature modulator 73 has a specific configuration example as shown in FIG. 3, the carrier signal SLC through the BPF 72 is supplied to the terminal 44.

In the example shown in FIG. 7, it is sufficient that only one local oscillator 12 is provided, and the carrier frequency of the output carrier digital signal SCI is
The same effect as that obtained by the example shown in FIG. 1 by setting the frequency of the oscillation output signal SL transmitted from the local oscillator 12 to be 3/4 times the fundamental oscillation frequency of the local oscillator 12 or the like. Various effects can be obtained. Further, in the frequency conversion section 71, the spurious signal formed together with the carrier signal SLC has the same frequency as the frequency of the carrier signal SLC, and generation of a spurious signal having a frequency near the carrier frequency of the carrier signal SLC is avoided. Is done. Note that a spurious signal having the same frequency as the frequency of the carrier signal SLC is easily suppressed by improving the linearity of the frequency conversion unit 71.

[0055]

As is apparent from the above description, in the digital signal transmitting apparatus according to the present invention, it is sufficient to provide only one local oscillating section. Therefore, two conventional local oscillating sections are required. As compared with the digital signal transmitting device to be used, it is possible to reduce the overall size, weight, power consumption, and the like. Since the carrier frequency of the output carrier digital signal transmitted from the wireless transmitter can be selected as being different from the fundamental oscillation frequency of the local oscillator, a part of the output carrier digital signal to be transmitted is fed back to the local oscillator. At this time, even if the degree of coupling of the feedback path from the wireless transmission unit to the local oscillation unit changes, the phase of the oscillation output signal transmitted from the local oscillation unit changes with the degree of coupling of the feedback path. Accordingly, it is possible to prevent a situation in which the output carrier signal changes, and as a result, it is possible to avoid a situation in which an error occurs in the output carrier digital signal.

Also, the carrier frequency of the output carrier digital signal can be, for example, 3/4 times the frequency of the oscillation output signal sent from the local oscillator, so that the output carrier digital signal can be converted by the frequency converter. The spurious signal formed together with the output carrier digital signal has the same frequency as the carrier frequency of the output carrier digital signal, so that generation of a spurious signal having a frequency near the carrier frequency of the output carrier digital signal can be avoided.

Further, when the carrier frequency of the output carrier digital signal is changed at a predetermined frequency interval of, for example, 25 KHz, the fundamental oscillation frequency of the local oscillator is changed at a predetermined frequency interval. In other words, if the local oscillator forms a PLL, the phase comparison frequency in the PLL can be higher than the frequency corresponding to the carrier frequency interval of the output carrier digital signal, whereby The frequency hopping time of the PLL formed by the local oscillation section can be shortened and the reference leak characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a digital signal transmitting apparatus according to the present invention.

FIG. 2 is a block diagram showing a PLL formed by a local oscillator in the example of the digital signal transmitting apparatus according to the present invention.

FIG. 3 is a block diagram showing a specific configuration example of a quadrature modulation unit in an example of a digital signal transmission device according to the present invention.

FIG. 4 is a block diagram illustrating a specific configuration example of a 90-degree phase shift unit in the specific configuration example of the quadrature modulation unit illustrated in FIG. 3;

FIG. 5 is a waveform chart used for describing the operation of a specific configuration example of the 90-degree phase shifter shown in FIG. 4;

FIG. 6 is a block diagram showing components that can be replaced with a part in an example of the digital signal transmitting apparatus according to the present invention.

FIG. 7 is a block diagram showing another example of the digital signal transmitting apparatus according to the present invention.

FIG. 8 is a block diagram showing an example of a conventional digital signal transmission device.

FIG. 9 is a block diagram showing an example of a conventional digital signal transmission device.

FIG. 10 is a frequency spectrum showing a spurious signal generation state at an output side of a frequency conversion unit used in an example of a conventional digital signal transmission device.

[Explanation of symbols]

11 Digital signal generator 12 Local oscillator
14 amplifying unit 15 transmitting antenna 21, 73 quadrature modulating unit
22 signal distribution unit 23, 32, 65, 66 frequency divider 24 LPF
25, 71 Frequency converter 26, 72 BP
F 31 Reference oscillator 33 Phase comparator
34 Filter 35 Variable frequency divider 36
VCO 42, 43, 63, 64 Multiplier 45 90-degree phase shifter 46, 67 Signal synthesizer 50 Frequency 2
Multiplier 51, 52 Latch 53D-FF

Claims (10)

[Claims] A digital signal generator for transmitting a digital baseband signal; a local oscillator for transmitting an oscillation output signal having a predetermined frequency; a first distribution signal and a second distribution signal for the oscillation output signal; A signal distributing section for distributing the signal as a signal; a frequency dividing section for dividing the first distributed signal to obtain a frequency-divided signal; quadrature modulation of the frequency-divided signal as a carrier signal on the carrier signal using the digital baseband signal , A quadrature modulator for obtaining a carrier digital signal, a frequency converter for performing frequency conversion on the carrier digital signal using the second distribution signal to obtain an output carrier digital signal, And a wireless transmission unit for wirelessly transmitting the signal. 2. A 90-degree phase shifter for obtaining a first carrier signal and a second carrier signal having a 90-degree mutual phase difference based on the carrier signal using the divided signal as a carrier signal, A first multiplier for multiplying the first carrier signal by the digital baseband signal to obtain a first multiplied output signal; and multiplying the second carrier signal by the digital baseband signal. A second multiplier for obtaining a second multiplied output signal, the first multiplied output signal and the second multiplied signal;
2. A digital signal transmitting apparatus according to claim 1, further comprising: a signal synthesizing unit for synthesizing the multiplied output signal of (i) and (ii) to obtain a carrier digital signal. 3. A frequency divider obtains a first frequency-divided signal and a second frequency-divided signal having a mutual phase difference of 90 degrees. A first multiplication unit for multiplying the first carrier signal and the digital baseband signal as a carrier signal to obtain a first multiplied output signal, and using the second frequency-divided signal as a second carrier signal A second multiplier for multiplying a second carrier signal by the digital baseband signal to obtain a second multiplied output signal;
2. A digital signal transmitting apparatus according to claim 1, further comprising a signal synthesizing section for synthesizing said first multiplied output signal and said second multiplied output signal to obtain a carrier digital signal. . 4. The digital signal according to claim 1, wherein the frequency dividing section performs 1 / N frequency division on the first distributed signal by setting N to a power multiplier of 2 which is 4 or more. Transmission device. 5. The frequency converter according to claim 1, wherein the carrier frequency of the output carrier digital signal is a frequency obtained by subtracting the carrier frequency of the carrier digital signal from the frequency of the second distribution signal. A digital signal transmitting device according to 2, 3, or 4. 6. A digital signal generator for transmitting a digital baseband signal, a local oscillator for transmitting an oscillation output signal having a predetermined frequency, a first distribution signal and a second distribution signal for the oscillation output signal. A signal distributor for distributing the signal as a signal, a frequency divider for dividing the first distributed signal to obtain a frequency-divided signal, and performing frequency conversion on the frequency-divided signal using the second distributed signal. A frequency conversion unit that obtains a carrier signal, a quadrature modulation unit that performs orthogonal modulation on the carrier signal with the digital baseband signal to obtain an output carrier digital signal, and a wireless transmission unit that wirelessly transmits the output carrier digital signal. Digital signal transmission device provided and configured. 7. A 90-degree phase shifter for obtaining a first carrier signal and a second carrier signal having a mutual phase difference of 90 degrees based on a carrier signal from a frequency converter. A first multiplication unit that performs multiplication of the carrier signal and the digital baseband signal to obtain a first multiplied output signal;
A second multiplier for multiplying the second carrier signal by the digital baseband signal to obtain a second multiplied output signal; and a first multiplied output signal and the second multiplied output signal. 7. The digital signal transmitting apparatus according to claim 6, further comprising a signal synthesizing unit for obtaining a carrier digital signal by synthesizing. 8. The digital signal transmitting apparatus according to claim 6, wherein the frequency dividing unit performs 1 / N frequency division on the first distributed signal, where N is a power of 2 which is 4 or more. . 9. The frequency converter according to claim 6, wherein the frequency of the carrier signal is a frequency obtained by subtracting the frequency of the frequency-divided signal from the frequency divider from the frequency of the second distribution signal. , 7 or 8. 10. The digital signal transmitting apparatus according to claim 1, wherein the local oscillator forms a phase locked loop.