JPH05136836A - Digital modulation signal generator - Google Patents

Abstract

PURPOSE:To obtain a digital modulation signal without an image signal by orthogonally modulating an error detection signal which does not affect a digital modulation signal output and adjusting amplitude and a phase by the signal in an orthogonal modulation signal generation part. CONSTITUTION:An orthogonal modulation signal generation part 100 converts an input data string in an SP converter 1 and it is separated into I/Q channels. The signals pass through filters 2a and 2b. Then, COSomegat is added to the I- channel and sinomegat to the Q-channel as the error detection signals by adders 11a and 11b. They pass through D/A converters 3a and 3b and LPF 4a and 4b. The output COSomegat of a local signal source 5 and the output sinomegat of a 90 deg. phase shifter 7a are mixed in mixers 6a and 6b and they are added in an adder 8. A signal generation part 100 modulates the error detection signals and a frequency conversion/output part 110 removes the error detection signal of the components of angular frequencies omegaL+omegae and omegaL-omegae in BPF 12, converts the frequency in a frequency converter 9 and adjusts the level in a level adjuster 10 so as to output it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital radio communication device, and more particularly to a signal generator having a quadrature modulation function used as a signal source.

[0002]

2. Description of the Related Art FIG. 5 shows a block diagram of a configuration of a conventional example.
In FIG. 5, the input data string is a serial / parallel converter.
Converted into 1 and separated into I and Q channels
It Each signal is a digital filter 2a, 2
b, D / A converters 3a and 3b, low-pass filter 4a,
The output co of the local signal source 5 after being processed by 4b
sω _LOutput of t and 90 ° phaser 7 −sin ω_Lt is Miki
Is mixed by the servers 6a and 6b, and added by the adder 8.
Frequency converter 9 and level adjuster 1 are added together.
It is output by 0.

[0003]

However, in the configuration of FIG. 5, since the mixers 6a and 6b and the 90 ° phase shifter 7 are not ideal, an amplitude difference between the I channel and the Q channel occurs, or an exact 90 ° phase shift occurs. There is a case where the phase difference is not obtained. For example, cosω _e t for the I channel and sin for the Q channel
When ω _e t is output from the serial / parallel converter 1, the output of the adder 8 ideally becomes as shown in equation (1). Adder 8 outputs _{= cosω e t × cosω L t} -sinω e t × sinω L t = cos (ω L + ω e) t ··· (1) However, the ideal mixer 6a, 6b and 90 ° phase shifter 7 Otherwise, there is a problem that the (ω _L −ω _e ) component, that is, the image is also generated. Therefore, an object of the present invention is to provide a digital modulation signal generator without the image component due to the characteristics of the mixer and the phase shifter, or a digital modulation signal generator for removing the image component due to the delay difference between the I and Q channel signals. Is to realize.

[0004]

In order to achieve such an object, a first aspect of the present invention relates to a digital signal processor for digitally processing a data signal sequence to obtain I channel and Q channel signals, and the above 2 Convert the signal to an analog signal,
A quadrature modulation signal generator that obtains a quadrature modulation wave by modulating the in-phase component and quadrature component of the carrier wave with each of the analog signals,
In the digital modulation signal generator provided with an output device that frequency-converts the quadrature-modulated wave, and adjusts and outputs the level,
A signal source for error detection provided in the digital signal processor, an adder for adding the error detection signal to the I and Q channel signals, and the error detection provided in the input section of the output device. A band pass filter for removing a signal, an error detector for separating a frequency component containing an error from the quadrature modulated wave to generate an error signal, a digital signal processor, or the quadrature modulated signal generator. A means for adjusting the I and Q channel signals or the analog signal according to the error signal is provided. A second aspect of the present invention is a digital signal processor for digitally processing a data signal sequence to obtain I-channel and Q-channel signals, and converting the two signals into analog signals. A digital modulation signal generator comprising a quadrature modulation signal generator that modulates a quadrature component to obtain a quadrature modulation wave, and an output device that frequency-converts the quadrature modulation wave, adjusts the level, and outputs An error detection signal source, an adder for adding the error detection signal to each of the I and Q channel signals, a delay line provided for the analog signal, and a variable delay time delay variable in delay time. A line, a bandpass filter for removing the error detection signal provided in the input part of the output device, and a frequency component including an error from the quadrature modulated wave. An error detector for generating a separation error signal and the digital signal processor, or the variable delay time delay line and the I and Q channel signals by the error signal provided in the quadrature modulation signal generator, or And means for adjusting the analog signal.

[0005]

A digital modulated signal having no image is generated by separating a frequency component containing an error from a quadrature modulated wave to generate an error signal, and adjusting the adjusting means of the quadrature modulated signal generator section with this error signal. You can

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.
1 is a block diagram showing the configuration of a first embodiment of a digital modulation signal generator according to the present invention. In FIG. 1, the same elements as those of the conventional example shown in FIG. Reference numeral 100 denotes a quadrature modulation signal generator, 11
Reference numeral 0 is a frequency conversion / output unit, and 120 is an amplitude / phase difference detection unit.

In the quadrature modulation signal generator 100, the input data string is converted by the serial / parallel converter 1 and I
Separate into channels and Q channels. After passing through the digital filters 2a and 2b, the respective signals are added by the adder 11
a, by 11b, cos .omega _e t to the I channel, sin .omega the Q channel _e t are each added as an error detection signal, D / A converter 3a, and is converted into an analog signal by 3b. However, the error detection signal uses a frequency band that does not affect the digital modulation signal output. These analog signals are D / A by the low pass filters 4a and 4b.
After the clock components of the converters 3a and 3b are removed, the output cos ω _L t of the local signal source 5 and the 90 ° phase shifter 7a
Output −sin ω _L t is mixed by mixers 6 a and 6 b, and added by adder 8.

Here, when the error of the amplitude α times and the phase β ° is included, the error detection signal is modulated by the quadrature modulation signal generator 100 as follows. _{cosω e t × cosω L t +} sinω e t {-α × sin (ω L t + β)} = 1/2 {cos (ω L + ω e) t + cos (ω L -ω e) t} + α / 2 {cos [(ω _{L + ω e) t + β} ] -cos [(ω L -ω e) t + β]} = 1/2 {cos (ω L + ω e) t + cos (ω L -ω e) t} + α / 2 {cos (ω L + ω _e ) t × cos β −sin (ω _L + ω _e ) t × sin β −cos (ω _L −ω _e ) t × cos β + sin (ω _L −ω _e ) t × sin β} = 1/2 (1 + α × cos β) × _{cos (ω L + ω e)} t -α / 2 × sinβ × sin (ω L + ω e) t +1/2 (1-α × cosβ) × cos (ω L -ω e) t + α / 2 × sinβ × sin (Ω _L −ω _e ) t (2)

In the frequency conversion / output unit 110, the band pass
Angular frequency (ω _L+ Ω_e) And (ω_L
−ω_e) Component error detection signal is removed, frequency conversion
Level converter 1 converts the frequency to microwave band etc.
Output after adjusting the level at 0.

In the amplitude / phase difference detecting section 120, the adder 8
Is mixed by the local signal source 14 having the angular frequency ω _m and the mixer 13, and the low-pass filter 15 extracts only the image component of the error detection signal. This image component is converted into a digital signal by the A / D converter 16 and then divided into two by the distributor 17.
The mixers 18a and 18b respectively use cos (ω _e −ω _L
−ω _m ) t and sin (ω _e −ω _L −ω _m ) t are mixed and passed through the low-pass filters 19a and 19b.
Using these outputs, the amplitude / phase error converter 20 calculates the amplitude error and the phase error, and the D / A converters 21a, 21
It is converted into an analog signal in b and output as an amplitude error signal 200 and a phase error signal 201. The phase shifter 7a is controlled by the amplitude error signal 200 and the phase error signal 201, and adjusts the amplitude and the phase so that the image is reduced.

Here, the quadrature modulation signal in the case of including the error of the amplitude α times and the phase β ° is expressed by the equation (2) as described above,
This signal is mixed by the local signal source 14 having the angular frequency ω _m and the mixer 13, and the low pass filter 15
When only the image component of the error detection signal is extracted by, the following expression is obtained. 1/2 (1-α × cos β) × cos (ω _L −ω _e −ω _m ) t + α / 2 × sin β × sin (ω _L −ω _e −ω _m ) t (3) Further, When (3) is mixed with cos (ω _e −ω _L −ω _m ) t and passes through the low pass filter 19a, 1/2 (1−α × cos β) = A (4) ) Is mixed with sin (ω _e −ω _L −ω _m ) t and passes through the low-pass filter 19b, α / 2 × sin β = B (5) Therefore, from the expressions (4) and (5), the amplitude difference α = 2 × B / sin β and the phase difference β = tan ⁻¹ {2 × B /
(1-2 × A)} is obtained.

FIG. 2 is a characteristic curve diagram showing the spectrum of each part in FIG. FIG. 2A shows the spectrum at the output of the adder 8, and "a" in the figure indicates an image component. FIG. 2B shows the spectrum at the output of the bandpass filter 12, and the broken line portion “B” shows the band of the bandpass filter 12. Therefore, the band pass filter 12 causes (ω _L + ω _e ) and (ω
_{The L} − ω _e ) component is removed. FIG. 2C shows a spectrum at the output of the mixer 13, and FIG. 2D shows a spectrum at the output of the low-pass filter 15.
Indicates the band of the low-pass filter. That is, only the (ω _e −ω _L −ω _m ) component is extracted from the quadrature modulation signal.

In FIG. 1, the amplitude and phase are adjusted by the phase shifter 7a by the error signals 200 and 201, but in addition to this, the amplitude of the error signal 200 is adjusted by the gain of the D / A converter. It is also possible to adjust the magnitude of the I component or Q component during digital signal processing or digital signal processing.
A method of adjusting the speed of the clock signal of the converter or the phase of the I component or the Q component during digital signal processing is also possible.

Further, in FIG. 3, the cause of image generation is amplitude.
Or the phase according to the present invention when there is only one of the phases.
Configuration block showing a second embodiment of the digital modulation signal generator.
It is a diagram. In FIG. 3, the first embodiment shown in FIG.
The same elements will be denoted by the same reference symbols and redundant description will be omitted.
It The quadrature modulation signal output from the adder 8 has an angular frequency (ω
_L−ω_e+ Δ) local signal source 14a and mixer 13
Is mixed by the bandpass filter 12b.
Ri (ω_L−ω_e) Component is taken out, and the power detector 22
Detected. The phase shifter 7a is controlled by this signal,
Adjust the amplitude or phase to reduce the image.
Therefore, in the second embodiment, the amplitude / position as shown in FIG.
Digital processing in the phase difference detector is unnecessary,
There is only one return path, and the bandpass filter 12b and power
It can be realized only by the detector 22.

FIG. 4 is a block diagram showing the configuration of a third embodiment of the digital modulation signal generator according to the present invention when there is a delay difference between the I and Q channel signals. I and Q
In the case where there is a delay difference between channel signals, I and Q
It can be considered that the channel signal is input from the outside. In this case, the phase difference between the I and Q channel signals changes depending on the frequency. As a result, even if the phase difference is adjusted so that the image is minimized at the frequency of the error detection signal, the phase difference between the I and Q channel signals is changed at frequencies other than this frequency, and the image is not minimized.

In FIG. 4, the same elements as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the duplicated description will be omitted. Here, the low-pass filters 4a and 4b and the mixer 6
delay line 23 and variable delay time delay line 2 between a and 6b
Place 4 respectively. The amplitude / phase error converter 20 calculates the amplitude error and two types of phase errors, and the D / A converter 2
1a, 21b and 21c are converted into analog signals, and the amplitude error signal 200 and the phase error signals 201 and 202 are respectively converted.
Output as. The phase shifter 7a is controlled by the amplitude error signal 200 and the phase error signal 201, and adjusts the amplitude and the phase so that the image is reduced. Also, the variable delay time delay line 24 is controlled by the phase error signal 202 to adjust the delay difference for the I and Q channel signals.

As the adjustment procedure of the third embodiment shown in FIG. 4, first of all, the phase difference between the error detection signals of two kinds of frequencies is obtained as the error detection signal. For example, when the angular frequencies of the error detection signal are ω ₁ and ω ₂ , the phase difference β ₁ = tan ⁻¹ {2 × B ₁ / (1-2) is obtained from equations (4) and (5). × A ₁ )} (6) β ₂ = tan ⁻¹ {2 × B ₂ / (1-2 × A ₂ )} (7) is obtained. Here, β ₁ and β ₂ are the phase differences when the angular frequencies are ω ₁ and ω ₂ .

[0018] from the phase error β ₀ β ₁ is not affected by the phase difference Δβ ₁ and frequency caused by the angular frequency ω _1,
That is, the relational expression of β ₁ = Δβ ₁ + β ₀ (8) holds. Similarly, β ₂ also becomes β ₂ = Δβ ₂ + β ₀ (9).

Secondly, the delay difference ΔD is obtained by the following equation by the equations (6) to (9). ΔD = (β ₂ −β ₁ ) / (f ₂ −f ₁ ) × (1/360 °) where ω ₁ = 2πf ₁ and ω ₂ = 2πf ₂ This delay difference ΔD is phased from the D / A converter 21c. The error signal 202 is output and the delay time of the variable delay time delay line 24 is set.

Third, after setting the variable delay time delay line 24, the angular frequency of the error detection signal is returned to ω ₁ , and the amplitude difference α = 2 × B ₁ / sin β, the same as in the _first embodiment. Phase difference β
₁ = tan ⁻¹ {2 × B ₁ / (1-2 × A ₁ )} is obtained,
The amplitude difference and the phase difference are output from the D / A converters 21b and 21a as the amplitude error signal 200 and the phase error signal 201, and the 90 ° phase shifter 7a is controlled. In the third embodiment shown in FIG. 4, the variable delay time delay line 24 is provided on the Q channel side as a means for correcting the delay difference, but it may be provided on the I channel side, and the variable delay time delay line is also provided. Instead of 24, a circuit having a variable delay time or the like may be used.

[0021]

As is clear from the above description,
The present invention has the following effects. In other words, the error detection signal that does not affect the output of the digital modulation signal is quadrature-modulated, and the quadrature-modulation signal generator adjusts the amplitude and phase by this modulated signal to obtain a digital modulation signal without an image. Be done. Also, I and Q
An image due to the difference in delay between channel signals can be simultaneously removed.

[Brief description of drawings]

FIG. 1 is a first digital modulation signal generator according to the present invention.
3 is a configuration block diagram showing an embodiment of FIG.

FIG. 2 is a characteristic curve diagram showing a spectrum of each point in the digital modulation signal generator of FIG.

FIG. 3 is a second digital modulation signal generator according to the present invention.
3 is a configuration block diagram showing an embodiment of FIG.

FIG. 4 is a third embodiment of the digital modulation signal generator according to the present invention.
3 is a configuration block diagram showing an embodiment of FIG.

FIG. 5 is a configuration block diagram showing an example of a conventional digital modulation signal generator.

[Explanation of symbols]

 1 serial-parallel converter 2a, 2b, 19a, 19b digital filter 3a, 3b, 21a, 21b, 21c D / A converter 4a, 4b, 15 low-pass filter 5,14 local signal source 6a, 6b, 13, 18a , 18b Mixer 7, 7a Phaser 8, 11a, 11b Adder 9 Frequency converter 10 Level adjuster 12 Bandpass filter 16 A / D converter 17 Distributor 20 Amplitude / phase error converter 22 Power detector 23 Delay line 24 Variable Delay Time Delay Line 100 Quadrature Modulation Signal Generation Unit 110 Frequency Conversion / Output Unit 120 Amplitude / Phase Difference Detection Unit 200 Amplitude Error Signal 201, 202 Phase Error Signal

Claims (2)

[Claims] 1. A digital signal processor for digitally processing a data signal sequence to obtain I-channel and Q-channel signals, and converting the two signals into analog signals, and the in-phase component and quadrature component of a carrier wave in each of these analog signals. A quadrature modulation signal generator for modulating a quadrature to obtain a quadrature modulation wave, and a digital modulation signal generator including an output device for frequency-converting the quadrature modulation wave, adjusting the level, and outputting Error detection signal source, an adder for adding the error detection signal to the I and Q channel signals, and a bandpass filter for removing the error detection signal provided at the input part of the output device An error detector that separates a frequency component containing an error from the quadrature modulated wave to generate an error signal, the digital signal processor, or The I and Q by the error signal in the serial quadrature modulation signal generator
A digital modulation signal generator comprising a channel signal or means for adjusting the analog signal. 2. A digital signal processor for digitally processing a data signal sequence to obtain I-channel and Q-channel signals, and converting the two signals into analog signals, with each of these analog signals the in-phase component and quadrature component of the carrier wave. A quadrature modulation signal generator for modulating a quadrature to obtain a quadrature modulation wave, and a digital modulation signal generator including an output device for frequency-converting the quadrature modulation wave, adjusting the level, and outputting An error detection signal source, an adder for adding the error detection signal to each of the I and Q channel signals, a delay line provided in the analog signal, and a variable delay time delay line having a variable delay time. A bandpass filter provided in the input part of the output device for removing the error detection signal, and a frequency component including an error from the quadrature modulated wave. An error detector for generating a separation error signal, the digital signal processor, or the variable delay time delay line and the I and Q channel signals by the error signal provided in the quadrature modulation signal generator, or A digital modulation signal generator, comprising: means for adjusting the analog signal.