JP4241353B2 - Arbitrary waveform generator - Google Patents

Description

The present invention relates to an arbitrary waveform generator , and more particularly to an arbitrary waveform generator suitable for generating a plurality of signals such as an IQ baseband signal for testing a digital communication device.

  Non-Patent Document 1 discloses an example of a practical digital IQ signal generator.

That is, Non-Patent Document 1 describes features, hardware configurations, usage examples, and the like of a baseband signal generator that supports a W-CDMA (Wideband-Code Division Multiple Access) system. .
However, there is no mention of a specific configuration for realizing a test signal generator capable of ensuring the desired level and frequency change degree desired by the present invention.

Digital IQ signal generator VB2000 7 Yokogawa Technical Report Vol.44 No.1 (2000) http://www.yokogawa.co.jp/TR/pdf/Japanese/2000-01/20000102.pdf

  Patent Document 1 relates to a multi-channel digital broadcast pseudo signal generator, and discloses a technique for generating a multi-channel digital broadcast pseudo signal that simulates a radio wave emission situation after the start of terrestrial digital broadcasting.

  Paragraph No. 0024 of this Patent Document 1 describes that digital broadcast pseudo signal waveform data is registered in advance in the waveform bank unit 13 that constitutes an arbitrary waveform generation unit that generates an OFDM signal. Paragraph number 0026 describes a method of generating an OFDM signal to be registered in each EPROM of the waveform bank unit 13, and indicates that complex data is output as a carrier of a digital broadcast pseudo signal. Paragraph number 0030 describes the final OFDM time waveform signal based on the complex data stored in the waveform bank unit 13.

  That is, the waveform bank unit 13 constituting the arbitrary waveform generation unit that generates the OFDM signal disclosed in Patent Document 1 stores a final OFDM time waveform signal based on complex data. This is different from the arbitrary waveform memory constituting the arbitrary waveform generator of the invention.

JP 2003-69524 A

  FIG. 5 is a block diagram showing an example of a conventional test signal generator. In FIG. 5, an arbitrary waveform generator 10 generates an IQ baseband signal, and a high-frequency signal generator 20 has an IQ modulation function, and is modulated by the IQ baseband signal generated by the arbitrary waveform generator 10. Generate high frequency signals. Note that I in IQ represents an in-phase component with an initial of Inphase, and Q represents an orthogonal component with an initial of Quadrature.

  Here, the arbitrary waveform generator 10 is roughly divided into two systems, an I signal system and a Q signal system.

  The I signal system includes an arbitrary waveform memory 11 that stores an arbitrary waveform to be generated for the I signal, a D / A converter 12 that converts an output of the arbitrary waveform memory 11 into an analog waveform, and a conversion output of the D / A converter 12 And a waveform shaping unit 13 that performs gain / offset adjustment, filter processing, and the like.

  The Q signal system includes an arbitrary waveform memory 14 that stores an arbitrary waveform to be generated for the Q signal, a D / A converter 15 that converts the output of the arbitrary waveform memory 14 into an analog waveform, and a conversion output of the D / A converter 15 And a waveform shaping unit 16 that performs gain / offset adjustment, filter processing, and the like.

  In such a configuration, when the test signal is generated, the I and Q signals to be modulated waves are written in the arbitrary waveform memories 11 and 14, respectively.

By the way, as an application of such a test signal generator, there is a case where it is desired to generate a test signal that simultaneously includes an interference wave and a desired wave. Therefore, in generating the test signal that includes the interference wave and the desired wave at the same time in the conventional configuration shown in FIG.
1) Write IQ signals, which are pre-combined interference wave and desired wave, to each arbitrary waveform memory 11, 14
2) Prepare multiple arbitrary waveform generators 10 for interfering and desired waves, add and synthesize those outputs, and input to high frequency signal generator 20
3) A method has been adopted in which an arbitrary waveform generator 10 and a high-frequency signal generator 20 are prepared for the interference wave and the desired wave, and the outputs of the high-frequency signal generators 20 are added and synthesized.

However, in the former two methods, when the relationship between the level and frequency of the disturbing wave and the desired wave is to be changed, the waveform itself written in the arbitrary waveform memories 11 and 14 must be changed. Lacks freedom of change.
On the other hand, according to the third method, the degree of freedom of change can be ensured, but there is a problem in terms of cost because it is necessary to prepare a plurality of high-frequency and large-scale high-frequency signal generators 20.

The present invention solves these conventional problems, and an object of the present invention is to provide an arbitrary waveform generator capable of ensuring a degree of freedom to change the relationship between levels and frequencies between a plurality of signals with a relatively inexpensive configuration . Is to provide.

Among the present inventions that achieve such problems, the invention of claim 1
First and second arbitrary waveform memories for storing first waveform data and second waveform data;
A complex sine wave generator having a cosine wave output terminal and a sine wave output terminal and outputting two orthogonal sine waves;
The first arbitrary waveform memory has a first input terminal and an output terminal each consisting of an imaginary number terminal and a real number terminal, and an output terminal of the first arbitrary waveform memory is connected to a real number terminal of the first input terminal, The output terminal of the arbitrary waveform memory is connected to the imaginary terminal of the first input terminal, and the cosine wave output terminal of the complex sine wave generator is connected to the real terminal of the second input terminal. A sine wave output terminal of the output of the complex sine wave generator is connected to the imaginary terminal of the input terminal, and a complex multiplier that performs complex multiplication of the output of the arbitrary waveform memory and the output of the complex sine wave generator,
Consists of analog waveform processing means for individually converting the real side output data and the imaginary side output data of the complex multiplier to an analog waveform and shaping the output,
An arbitrary waveform generator characterized in that it generates two orthogonal signals.

The invention according to claim 2 is the arbitrary waveform generator according to claim 1,
The real terminal of one input terminal of the complex multiplier is connected to one input terminal of the first multiplier and one input terminal of the second multiplier,
The imaginary terminal of one input terminal of the complex multiplier is connected to one input terminal of the third multiplier and one input terminal of the fourth multiplier,
The real terminal of the other input terminal of the complex multiplier is connected to the other input terminal of the first multiplier and the other input terminal of the fourth multiplier,
The imaginary terminal of the other input terminal of the complex multiplier is connected to the other input terminal of the second multiplier and the other input terminal of the third multiplier,
The output terminal of the first multiplier is connected to the addition terminal of the subtracter, the output terminal of the second multiplier is connected to one input terminal of the adder, and the output terminal of the third multiplier is connected to the subtracter. Connected to the subtraction terminal, the output terminal of the fourth multiplier is connected to the other input terminal of the adder,
The output terminal of the subtractor is connected to the real terminal of the output terminal of the complex multiplier, and the output terminal of the adder is connected to the imaginary terminal of the output terminal of the complex multiplier.

The invention according to claim 3 is the arbitrary waveform generator according to claim 1,
The complex sine wave generator is a numerical operation oscillator using a phase accumulator and a sine wave table.

The invention according to claim 4 is the arbitrary waveform generator according to any one of claims 1 to 3,
An IQ baseband signal is output.

ADVANTAGE OF THE INVENTION According to this invention, the arbitrary waveform generator which can ensure the freedom degree which changes the relationship of the level and frequency between several signals with a comparatively cheap structure is realizable.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and the same reference numerals are given to portions common to FIG.
1, the output terminal of the arbitrary waveform memory 11 is connected to the real terminal Re. Of one input terminal IN1 of the complex multiplier 30, and the output terminal of the arbitrary waveform memory 14 is connected to one input terminal IN1 of the complex multiplier 30. Connected to imaginary terminal Im. The cosine wave output terminal cosωt of the complex sine wave generator 40 is connected to the real terminal Re. Of the other input terminal IN2 of the complex multiplier 30, and the imaginary terminal Im. Of the other input terminal IN2 of the complex multiplier 30 is connected to the real terminal Re. A sine wave output terminal sinωt that is an output of the complex sine wave generator 40 is connected. The real terminal Re. Of the output terminal OUT of the complex multiplier 30 is connected to the input terminal of the D / A converter 12, and the imaginary terminal Im. Of the output terminal OUT of the complex multiplier 30 is connected to the D / A converter 15. Connected to the input terminal.

  FIG. 2 is a block diagram showing a specific example of the complex multiplier 30. The complex multiplier 30 includes, for example, four multipliers 31 to 34, a subtracter 35, and an adder 36.

  The real terminal Re. Of one input terminal IN1 of the complex multiplier 30 is connected to one input terminal of the multiplier 31 and one input terminal of the multiplier 32, and the imaginary terminal of one input terminal IN1 of the complex multiplier 30. Im. Is connected to one input terminal of the multiplier 33 and one input terminal of the multiplier 34.

  The real terminal Re. Of the other input terminal IN2 of the complex multiplier 30 is connected to the other input terminal of the multiplier 31 and the other input terminal of the multiplier 34, and the imaginary terminal of the other input terminal IN2 of the complex multiplier 30. Im. Is connected to the other input terminal of the multiplier 32 and the other input terminal of the multiplier 33.

  The output terminal of the multiplier 31 is connected to the addition terminal of the subtractor 35, the output terminal of the multiplier 32 is connected to one input terminal of the adder 36, and the output terminal of the multiplier 33 is connected to the subtraction terminal of the subtractor 35. The output terminal of the multiplier 34 is connected to the other input terminal of the adder 36.

  The output terminal of the subtractor 35 is connected to the real terminal Re. Of the output terminal OUT of the complex multiplier 30, and the output terminal of the adder 36 is connected to the imaginary terminal Im. Of the output terminal OUT of the complex multiplier 30. Yes.

  As the complex sine wave generator 40, for example, a numerical operation oscillator (NCO) using a phase accumulator and a sine wave table is used. The complex sine wave generator 40 generates two orthogonal sine wave signals cosωt and sinωt.

The operation of FIGS. 1 and 2 will be described. If the output signal of the arbitrary waveform memory 11 is I ′, the output signal of the arbitrary waveform memory 14 is Q ′, and the output of the complex sine wave generator 40 is exp (jωt), the output (I + jQ) of the complex multiplier 30 is Indicated by
I + jQ = (I ′ + jQ ′) · exp (jωt)
This represents an operation of translating the frequency spectrum of the complex signal represented by (I ′ + jQ ′) by the frequency ω. That is, the spectrum of the memory waveform can be arbitrarily moved according to the value of ω of the complex multiplier 30. Incidentally, if ω = 0, the spectrum is not moved.

  According to such a configuration of the arbitrary waveform generation unit 10, it is possible to change the center frequency of the output IQ signal without rewriting the waveforms written in the arbitrary waveform memories 11 and 14.

  Therefore, by using such an IQ signal as an input of the high frequency signal generator 20 having the IQ modulation function, the arbitrary waveform generator 10 is configured even if the set frequency on the high frequency signal generator 20 side is fixed. By changing the frequency of the complex sine wave generator 40, the output frequency of the high-frequency signal generator 20 can be arbitrarily changed.

  FIG. 3 is a block diagram showing an example of a test signal generator configured to generate a test signal that simultaneously includes an interference wave and a desired wave according to the present invention. In FIG. 3, each of the arbitrary waveform generators 50 and 60 is configured as shown in FIG. The I signal output terminal of the arbitrary waveform generator 50 is connected to one input terminal of the adder 71, and the Q signal output terminal of the arbitrary waveform generator 50 is connected to one input terminal of the adder 72. The I signal output terminal of the arbitrary waveform generator 60 is connected to the other input terminal of the adder 71, and the Q signal output terminal of the arbitrary waveform generator 60 is connected to the other input terminal of the adder 72. The output terminal of the adder 71 is connected to the I signal input terminal of the high frequency signal generator 20, and the output terminal of the adder 72 is connected to the Q signal input terminal of the high frequency signal generator 20.

  Here, it is assumed that the baseband waveform of the desired wave is written in the arbitrary waveform memory of the arbitrary waveform generation unit 50, and the baseband waveform of the interference wave is written in the arbitrary waveform memory of the arbitrary waveform generation unit 60. When the set frequency of the complex sine wave generator of the arbitrary waveform generator 50 is ω1, the frequency of the complex sine wave generator of the arbitrary waveform generator 60 is ω2, and the set frequency of the high frequency signal generator 20 is ωc, the high frequency signal A combined waveform of the desired wave and the interference wave as shown in FIG.

In FIG. 4, the frequency relationship between the desired wave and the interference wave can be arbitrarily changed by setting ω1 and ω2. Further, the level relationship between the desired wave and the interference wave can be adjusted by the respective gain adjustment functions of the arbitrary waveform generator 50 and the arbitrary waveform generator 60.
As a result, it is possible to generate a test signal including a desired wave and a disturbing wave with a high degree of freedom at a low cost.

  In the above embodiment, an apparatus for outputting an IQ baseband signal has been described. However, the present invention is also effective as various signal generators for testing digital communication devices such as mobile phones and digital broadcasts.

It is a block diagram which shows one Example of this invention. FIG. 2 is a block diagram illustrating a specific example of a complex multiplier 30 in FIG. 1. It is a block diagram which shows an example of the test signal generator which generates the test signal containing an interference wave and a desired wave simultaneously. FIG. 4 is an explanatory diagram of a combined waveform of a desired wave and an interference wave output from the apparatus of FIG. 3. It is a block diagram which shows an example of the conventional test signal generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11,14 Arbitrary waveform memory 12,15 D / A converter 13,16 Waveform shaping part 20 High frequency signal generation part 30 Complex arithmetic units 31-34 Multiplier 35 Subtractor 36,71,72 Adder 40 Complex sine wave generator 50,60 Arbitrary waveform generator

Claims (4)

First and second arbitrary waveform memories for storing first waveform data and second waveform data;
A complex sine wave generator having a cosine wave output terminal and a sine wave output terminal and outputting two orthogonal sine waves;
The first arbitrary waveform memory has a first input terminal and an output terminal each consisting of an imaginary number terminal and a real number terminal, and an output terminal of the first arbitrary waveform memory is connected to a real number terminal of the first input terminal, The output terminal of the arbitrary waveform memory is connected to the imaginary terminal of the first input terminal, and the cosine wave output terminal of the complex sine wave generator is connected to the real terminal of the second input terminal. A sine wave output terminal of the output of the complex sine wave generator is connected to the imaginary terminal of the input terminal, and a complex multiplier that performs complex multiplication of the output of the arbitrary waveform memory and the output of the complex sine wave generator,
Consists of analog waveform processing means for individually converting the real side output data and the imaginary side output data of the complex multiplier to an analog waveform and shaping the output,
An arbitrary waveform generator characterized by generating two orthogonal signals. The real terminal of one input terminal of the complex multiplier is connected to one input terminal of the first multiplier and one input terminal of the second multiplier,
The imaginary terminal of one input terminal of the complex multiplier is connected to one input terminal of the third multiplier and one input terminal of the fourth multiplier,
The real terminal of the other input terminal of the complex multiplier is connected to the other input terminal of the first multiplier and the other input terminal of the fourth multiplier,
The imaginary terminal of the other input terminal of the complex multiplier is connected to the other input terminal of the second multiplier and the other input terminal of the third multiplier,
The output terminal of the first multiplier is connected to the addition terminal of the subtracter, the output terminal of the second multiplier is connected to one input terminal of the adder, and the output terminal of the third multiplier is connected to the subtracter. Connected to the subtraction terminal, the output terminal of the fourth multiplier is connected to the other input terminal of the adder,
2. An arbitrary output terminal according to claim 1, wherein the output terminal of the subtractor is connected to the real number terminal of the output terminal of the complex multiplier, and the output terminal of the adder is connected to the imaginary number terminal of the output terminal of the complex multiplier. Waveform generator.   2. The arbitrary waveform generator according to claim 1, wherein the complex sine wave generator is a numerical operation oscillator using a phase accumulator and a sine wave table.   The arbitrary waveform generator according to any one of claims 1 to 3, wherein an IQ baseband signal is output.

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