JP2005217880A

JP2005217880A - Signal generator

Info

Publication number: JP2005217880A
Application number: JP2004023478A
Authority: JP
Inventors: Akitoshi Iwashita; 明暁岩下; Jun Konase; 純木名瀬
Original assignee: Anritsu Corp
Current assignee: Anritsu Corp
Priority date: 2004-01-30
Filing date: 2004-01-30
Publication date: 2005-08-11
Anticipated expiration: 2024-01-30
Also published as: JP3838648B2

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a modulation signal from being fluctuated in level when being outputted. <P>SOLUTION: A signal generating means 21 outputs a reference signal Sr to be reference of the modulation signal to be changed with amplitude constant to a level varying means 24 only for a first period of time when the modulation signal is changed. Loop control is performed so as to make a detection output to the reference signal Sr equal to a level setting voltage, and an output of a first low-pass filter 29 at that time is held and stored as a first reference voltage Vr1. After the first period of time has passed and a changed modulation signal Sm is outputted, and when a second period of time has further passed, an output of a second low-pass filter 31 which has a large time constant and is hardly affected by modulation is held and stored as a second reference voltage. After that. a value obtained by adding a second error signal corresponding to difference between the second reference voltage and the output of the second low-pass filter 31 to the first reference voltage controls the gain or attenuation quantity of the level varying means 24. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、各種変調信号を出力する信号発生装置において、変調信号の変更時の動作を高速化し、且つ変更後の出力レベルを安定化するための技術に関する。 The present invention relates to a technique for speeding up an operation when changing a modulation signal and stabilizing the output level after the change in a signal generator that outputs various modulation signals.

各種通信機器の測定等を行うため用いられる信号発生装置には、測定項目や測定対象に応じて無変調のキャリア信号の他に、振幅変調、周波数変調、デジタル直交変調等各種の変調を行った信号を出力できるようになっている。 In addition to the unmodulated carrier signal, the signal generator used to measure various communication devices performs various modulations such as amplitude modulation, frequency modulation, and digital quadrature modulation according to the measurement item and measurement target. A signal can be output.

また、このような測定に用いられる信号発生装置では、出力信号のレベルの変動が測定誤差となるため、その出力レベルを安定化するための回路が設けられている。 In addition, in the signal generator used for such measurement, since a fluctuation in the level of the output signal becomes a measurement error, a circuit for stabilizing the output level is provided.

この種のレベル安定化回路として一般的には、図８に示すように、安定化の対象となる信号Ｓを、減衰量可変の減衰器や増幅度可変の増幅器等のレベル可変手段１１に入力し、そのレベル可変手段１１の出力信号Ｂを分岐手段１２で２信号Ｄａ、Ｄｂに分岐してその一方Ｄａを検波手段１３で検波し、その検波出力Ｅと予め設定されたレベル設定電圧Ｖｓとの差を差動増幅器等からなる比較手段１４によって検出し、その差信号ＧをＬＰＦ（低域通過フィルタ）１５に入力して制御に不要な高域成分を除去し、高域成分が除去された信号を制御信号Ｃとしてレベル可変手段１１に与えてその減衰量や増幅度を可変させ、検波出力Ｅとレベル設定電圧Ｖｓとの差が無くなるようにフィードバック制御することで、検波手段１３に入力される信号Ｄａのレベル、即ち、分岐手段１２で分岐されて出力される他方の信号Ｄｂのレベルを安定化している。 As a level stabilization circuit of this type, generally, as shown in FIG. 8, a signal S to be stabilized is input to level variable means 11 such as an attenuator with variable attenuation or an amplifier with variable amplification. Then, the output signal B of the level varying means 11 is branched into two signals Da and Db by the branching means 12, and one of the signals Da is detected by the detecting means 13, and the detected output E and a preset level setting voltage Vs The difference signal G is detected by a comparison means 14 comprising a differential amplifier or the like, and the difference signal G is input to an LPF (low-pass filter) 15 to remove high-frequency components unnecessary for control, and the high-frequency components are removed. The control signal C is supplied to the level varying means 11 to vary the attenuation amount and the amplification degree, and feedback control is performed so that the difference between the detection output E and the level setting voltage Vs is eliminated. Signal a level, that is, to stabilize the level of the other signal Db output is branched by branching means 12.

このような構成で出力信号のレベルを安定化している信号発生装置では、ＬＰＦ１５の帯域と、出力信号のレベル変更速度、変調周波数、変調に用いる信号等の関係に起因して、以下のような問題が発生する。 In the signal generator that stabilizes the level of the output signal with such a configuration, the following is caused due to the relationship between the band of the LPF 15, the level change speed of the output signal, the modulation frequency, the signal used for modulation, and the like. A problem occurs.

例えば、出力信号のレベルを段階的に可変するためには、比較手段１４に対するレベル設定電圧Ｖｓを段階的に可変する必要があるが、このレベル設定電圧Ｖｓの変化速度に対してＬＰＦ１５の時定数が大きいと、レベル設定電圧Ｖｓを変更してから出力信号のレベルが安定になるまでに必要な時間が長くなってしまい、効率的な測定が行えない。 For example, in order to change the level of the output signal stepwise, it is necessary to change the level setting voltage Vs for the comparison means 14 stepwise. The time constant of the LPF 15 with respect to the changing speed of the level setting voltage Vs. If the value is large, it takes a long time to change the level setting voltage Vs until the level of the output signal becomes stable, and efficient measurement cannot be performed.

また、ディジタルのベースバンド信号で振幅変調された信号の場合、データ「０」が続いて信号振幅が０の期間が長くなると、レベル可変手段１１の利得が最大または減衰量が最小の状態に追い込まれ、この状態からデータ「１」に対応した振幅の信号が入力されると、その信号は、レベル可変手段１１によって最大に増幅されたりあるいは減衰をほとんど受けずに分岐手段１２および検波手段１３に入力されることになり、測定対象に過大なレベルの信号を与えて測定対象を壊す恐れがある。 Further, in the case of a signal that is amplitude-modulated with a digital baseband signal, if the period in which the signal amplitude is 0 continues after the data “0”, the gain of the level variable means 11 is maximized or the attenuation is minimized. When a signal having an amplitude corresponding to the data “1” is input from this state, the signal is amplified to the maximum by the level varying means 11 or hardly attenuated, and is supplied to the branching means 12 and the detecting means 13. As a result, an excessively high level signal is given to the measurement target, which may destroy the measurement target.

また、上記の点を改善するために、ＬＰＦ１５の時定数を小さくすると、フィードバックループの応答速度が信号Ｓの変調成分による振幅変化の速度に追いつき、その振幅変化を抑圧して変調波形に歪みを発生させてしまうので、精度の高い変調信号が発生できなくなってしまう。 Further, if the time constant of the LPF 15 is reduced in order to improve the above point, the response speed of the feedback loop catches up with the speed of the amplitude change due to the modulation component of the signal S, and the amplitude change is suppressed to distort the modulation waveform. As a result, a highly accurate modulation signal cannot be generated.

上記問題を解決するために、出力信号の変調状態や出力可変の状態に応じて、フィードバックループによる自動的なレベルを安定化する動作と、フィードバックループを開いてレベル可変手段１１に固定電圧を与え、その利得や減衰量が一定の状態で信号を出力させる動作とを切り替える方法が考えられる。 In order to solve the above problem, an operation for stabilizing the automatic level by the feedback loop in accordance with the modulation state of the output signal and the variable output state, and a fixed voltage is applied to the level variable means 11 by opening the feedback loop. A method of switching between the operation of outputting a signal in a state where the gain or attenuation is constant can be considered.

なお、信号発生装置ではないが、受信装置でその受信出力を安定化するための技術に関し、上記のようにフィードバックループによる自動的なレベルを安定化する動作と、フィードバックループを開いて固定の利得や減衰量で信号を出力させる動作とを切り替える技術が次の特許文献１に開示されている。 Although not a signal generator, it relates to the technology for stabilizing the reception output at the receiver, and as described above, the operation for stabilizing the automatic level by the feedback loop and the fixed gain by opening the feedback loop. A technique for switching between the operation of outputting a signal with an attenuation amount and the operation of outputting a signal with the amount of attenuation is disclosed in the following Patent Document 1.

特開２００２−２９０１８０JP 2002-290180 A

しかしながら、上記のように固定の利得や減衰量で変調信号を継続的に出力させる方法では、環境変化等の影響で出力信号のレベルが変動してしまう。 However, in the method of continuously outputting a modulation signal with a fixed gain or attenuation as described above, the level of the output signal varies due to the influence of an environmental change or the like.

また、実際に出力しようとする変調信号に基づいて、固定の利得や減衰量を設定する方法では、再現性が低く、測定精度が悪化してしまう。 Also, the method of setting a fixed gain or attenuation based on the modulation signal to be actually output has low reproducibility and deteriorates measurement accuracy.

本発明は、この問題を解決し、変調信号を出力しているときでも、環境変化等の影響による出力信号のレベル変動を防ぐことができ、再現性および精度が高い測定を可能とする信号発生装置を提供することを目的としている。 The present invention solves this problem, and even when a modulated signal is output, it can prevent fluctuations in the level of the output signal due to the influence of environmental changes, etc., and signal generation that enables measurement with high reproducibility and accuracy The object is to provide a device.

前記目的を達成するために、本発明の請求項１の信号発生装置は、
定常時には振幅変調された変調信号を出力し、前記変調信号が変更されるときに、該変調信号の出力レベルの基準となる振幅一定の基準信号を第１の時間だけ出力し、該第１の時間が経過した後に前記変更された変調信号を出力する信号発生手段（２１）と、
入力される制御信号に応じて、前記信号発生手段の出力信号のレベルを可変して出力するために減衰量または増幅度が可変可能となっているレベル可変手段（２４）と、
前記レベル可変手段の出力信号を分岐する分岐手段（２５）と、
前記分岐手段によって分岐された一方の信号（Ｄａ）を検波する検波手段（２６）と、
前記検波手段の出力信号と予め設定されたレベル設定電圧（Ｖｓ）とを比較し、その差である第１の誤差信号（Ｇ）を出力する第１の比較手段（２７）と、
前記第１の比較手段から出力された第１の誤差信号を受けて第１周波数以下の信号成分を通過させる第１の低域通過フィルタ（２９）と、
前記信号発生手段が前記基準信号を出力してから前記第１の時間が経過する直前に前記第１の低域通過フィルタから出力されている信号の電圧（Ｈ）を第１基準電圧として記憶保持する第１の保持手段（３０）と、
前記検波手段の出力信号を受けて、前記第１周波数より低く且つ前記変調信号の変調周波数より低い第２周波数以下の信号成分を通過させる第２の低域通過フィルタ（３１）と、
前記信号発生手段が前記基準信号を出力してから前記第１の時間が経過し、さらに前記第２の低域通過フィルタの時定数に応じた第２の時間が経過したときに前記第２の低域通過フィルタから出力されている信号の電圧を第２基準電圧として記憶保持する第２の保持手段（３３）と、
前記第２の保持手段に前記第２基準電圧が保持された後に前記第２の低域通過フィルタから出力される信号と前記第２基準電圧とを比較し、その差に応じた第２の誤差信号を出力する第２の比較手段（３４）と、
前記信号発生手段が前記基準信号を出力してから前記第１の時間が経過するまでの間は、前記第１の低域通過フィルタの出力信号を制御信号として前記レベル可変手段に与え、前記基準信号に対する前記検波手段の出力信号の電圧が前記レベル設定電圧に等しくなるように追い込み制御し、前記第１の時間が経過してから前記第２の時間が経過するまでの間は、前記第１基準電圧を制御信号として前記レベル可変手段に与えて変更された前記変調信号を固定利得で出力させ、前記第２の時間が経過した後には、前記第１基準電圧と前記第２の誤差信号とを加算した信号を制御信号として前記レベル可変手段に与えて変更された前記変調信号の出力レベルの変動を抑制するレベル制御手段（４０）とを備えている。 In order to achieve the above object, a signal generator according to claim 1 of the present invention comprises:
A modulated signal that is amplitude-modulated is output in a steady state, and when the modulated signal is changed, a reference signal having a constant amplitude that serves as a reference for the output level of the modulated signal is output for a first time. Signal generating means (21) for outputting the modified modulation signal after a lapse of time;
Level variable means (24) in which the amount of attenuation or the degree of amplification can be varied in order to vary and output the level of the output signal of the signal generating means in accordance with the input control signal;
Branching means (25) for branching the output signal of the level varying means;
Detection means (26) for detecting one signal (Da) branched by the branch means;
A first comparison means (27) for comparing the output signal of the detection means with a preset level setting voltage (Vs) and outputting a first error signal (G) which is the difference between the output signal and the level setting voltage (Vs);
A first low-pass filter (29) for receiving a first error signal output from the first comparing means and passing a signal component of a first frequency or lower;
The voltage (H) of the signal output from the first low-pass filter is stored as a first reference voltage immediately before the first time elapses after the signal generating means outputs the reference signal. First holding means (30) to perform,
A second low-pass filter (31) that receives the output signal of the detection means and passes a signal component that is lower than the first frequency and lower than the modulation frequency of the modulation signal;
When the first time has elapsed since the signal generating means output the reference signal, and when the second time corresponding to the time constant of the second low-pass filter has elapsed, the second time Second holding means (33) for storing and holding the voltage of the signal output from the low-pass filter as a second reference voltage;
A signal output from the second low-pass filter after the second reference voltage is held in the second holding means is compared with the second reference voltage, and a second error corresponding to the difference is compared. Second comparing means (34) for outputting a signal;
The output signal of the first low-pass filter is supplied as a control signal to the level variable means until the first time elapses after the signal generating means outputs the reference signal, and the reference Drive-in control is performed so that the voltage of the output signal of the detection unit with respect to the signal becomes equal to the level setting voltage, and the first time is elapsed until the second time elapses. The modulation signal changed by applying a reference voltage as a control signal to the level varying means is output with a fixed gain, and after the second time has elapsed, the first reference voltage, the second error signal, Level control means (40) that suppresses fluctuations in the output level of the modulated signal that has been changed by giving a signal obtained by adding to the level variable means as a control signal.

また、本発明の請求項２の信号発生装置は、請求項１の信号発生装置において、
前記信号発生手段（２１）は、
ベースバンド信号を出力するベースバンド信号発生部（２１ａ）と、
キャリア信号を発生するキャリア信号発生部（２１ｂ）と、
前記キャリア信号の振幅を、前記ベースバンド信号の電圧に応じて線形的に変化させて前記変調信号を出力する振幅変調器（２１ｃ）と、
前記基準信号を出力する基準信号発生手段（２１ｄ）と、
前記変調信号と前記基準信号とを選択的に出力する信号切替手段（２１ｅ）とから構成されることを特徴としている。 The signal generator of claim 2 of the present invention is the signal generator of claim 1,
The signal generating means (21)
A baseband signal generator (21a) for outputting a baseband signal;
A carrier signal generator (21b) for generating a carrier signal;
An amplitude modulator (21c) that linearly changes the amplitude of the carrier signal according to the voltage of the baseband signal and outputs the modulated signal;
Reference signal generating means (21d) for outputting the reference signal;
It is characterized by comprising signal switching means (21e) for selectively outputting the modulation signal and the reference signal.

また、本発明の請求項３の信号発生装置は、請求項１の信号発生装置において、
前記信号発生手段（２１）は、
ベースバンド信号を出力するベースバンド信号発生部（２１ａ）と、
キャリア信号を発生するキャリア信号発生部（２１ｂ）と、
前記キャリア信号の振幅を、前記ベースバンド信号の電圧に応じて線形的に変化させて変調信号を出力する振幅変調器（２１ｃ）と、
前記基準信号を発生するときには、前記ベースバンド信号発生部にベースバンド信号の出力電圧を一定にするための信号を出して前記基準信号を前記振幅変調器が出力するように制御する信号切替手段（２１ｆ）とから構成されることを特徴としている。 The signal generator of claim 3 of the present invention is the signal generator of claim 1,
The signal generating means (21)
A baseband signal generator (21a) for outputting a baseband signal;
A carrier signal generator (21b) for generating a carrier signal;
An amplitude modulator (21c) that linearly changes the amplitude of the carrier signal according to the voltage of the baseband signal and outputs a modulated signal;
When generating the reference signal, a signal switching means for controlling the amplitude signal to be output by outputting a signal for making the output voltage of the baseband signal constant to the baseband signal generation unit. 21f).

また、本発明の請求項４の信号発生装置は、請求項１の信号発生装置において、
前記信号発生手段（２１）は、
ベースバンド信号（Ｉ、Ｑ）と９０度位相が異なる２相の正弦波信号（ｃｏｓ ω_ｓｔ、ｓｉｎω_ｓｔ）を選択的に出力するベースバンド信号発生部（２１ｇ）と、
前記ベースバンド信号に応じて変調信号を出力する直交変調器（２１ｈ）と、
前記基準信号を発生するときには、前記ベースバンド信号発生部が前記正弦波信号を出力するための信号を出して前記基準信号を前記直交変調器が出力するように制御する信号切替手段（２１ｉ）とから構成されることを特徴としている。 The signal generator of claim 4 of the present invention is the signal generator of claim 1,
The signal generating means (21)
Baseband signals (I, Q) and 90 ° phase difference two-phase sinusoidal signals _{_{(cos ω s t, sinω s}} t) baseband signal generator for outputting selectively the the (21g),
A quadrature modulator (21h) that outputs a modulation signal in accordance with the baseband signal;
A signal switching means (21i) for controlling the baseband signal generator to output a signal for outputting the sine wave signal so that the quadrature modulator outputs the reference signal when generating the reference signal; It is characterized by comprising.

また、本発明の請求項５の信号発生装置は、請求項１乃至４の信号発生装置において、
前記第２の低域通過フィルタを通過した信号成分（Ｊ）をデジタル信号に変換して前記第２の保持手段と前記第２の比較手段に出力するＡ／Ｄ変換器（３２）を備え、
前記第２の比較手段は、前記第２基準電圧と前記変換されたデジタル信号との大小比較値を出力し、
前記レベル制御手段（４０）は、
前記大小比較値を順次累積する累積手段（４１）と、前記累積された大小比較値に所定の電圧（ΔＶ）を乗じて誤差電圧を出力する乗算手段（４２）と、前記誤差電圧を変換して第１のアナログ電圧を出力するＤ／Ａ変換手段（４３）と、前記第１基準電圧と前記第1のアナログ電圧に変換された誤差電圧とを加算して第２のアナログ電圧を出力する加算手段（４４）と、前記前１基準電圧、前記２基準電圧、または前記第２のアナログ電圧のいずれか一つを選択して前記制御信号として出力するスイッチ（４５）とから構成されることを特徴としている。 The signal generator of claim 5 of the present invention is the signal generator of claims 1 to 4,
An A / D converter (32) that converts the signal component (J) that has passed through the second low-pass filter into a digital signal and outputs the digital signal to the second holding means and the second comparing means;
The second comparing means outputs a magnitude comparison value between the second reference voltage and the converted digital signal,
The level control means (40)
Accumulating means (41) for sequentially accumulating the magnitude comparison values, multiplication means (42) for multiplying the accumulated magnitude comparison values by a predetermined voltage (ΔV) and outputting an error voltage, and converting the error voltage. D / A conversion means (43) for outputting the first analog voltage, and adding the first reference voltage and the error voltage converted to the first analog voltage to output a second analog voltage. It comprises an adding means (44) and a switch (45) for selecting any one of the front 1 reference voltage, the 2 reference voltage, or the second analog voltage and outputting it as the control signal. It is characterized by.

また、本発明の請求項６の信号発生装置は、請求項１乃至４の信号発生装置において、
前記第２の低域通過フィルタを通過した信号成分（Ｊ）をデジタル信号に変換して前記第２の保持手段と前記第２の比較手段に出力するＡ／Ｄ変換器（３２）を備え、
前記第２の比較手段は、前記第２基準電圧と前記変換されたデジタル信号との差分値を出力し、
前記レベル制御手段（４０）は、
前記差分値に所定の係数（α）を乗じて誤差電圧を出力する乗算手段（４７）と、前記誤差電圧を変換して第３のアナログ電圧を出力するＤ／Ａ変換手段（４３）と、前記第１基準電圧と前記第３のアナログ電圧に変換された誤差電圧とを加算して第４のアナログ電圧を出力する加算手段（４４）と、前記前１基準電圧、前記２基準電圧、または前記第４のアナログ電圧のいずれか一つを選択して前記制御信号として出力するスイッチ（４５）とから構成されることを特徴としている。 The signal generator of claim 6 of the present invention is the signal generator of claims 1 to 4,
An A / D converter (32) that converts the signal component (J) that has passed through the second low-pass filter into a digital signal and outputs the digital signal to the second holding means and the second comparing means;
The second comparing means outputs a difference value between the second reference voltage and the converted digital signal,
The level control means (40)
A multiplication means (47) for multiplying the difference value by a predetermined coefficient (α) and outputting an error voltage; a D / A conversion means (43) for converting the error voltage and outputting a third analog voltage; An adding means (44) for adding the first reference voltage and the error voltage converted into the third analog voltage to output a fourth analog voltage; and the previous one reference voltage, the second reference voltage, or It is characterized by comprising a switch (45) for selecting any one of the fourth analog voltages and outputting it as the control signal.

このように構成したため、本発明の信号発生装置では、変調信号が変更されるときに、振幅一定で変更される変調信号の基準となる基準信号が第１の時間だけレベル可変手段に入力され、その基準信号に対する検波出力がレベル設定電圧に等しくなるようにループ制御がなされ、そのときの第１の低域通過フィルタの出力信号の電圧が第１基準電圧として保持記憶される。ここで、基準信号が無変調であるために第１の低域通過フィルタに要求される時定数は非常に小さくて済むので、第１基準電圧を得るのに必要な時間、即ち、第１の時間は僅少で済む。そして、この第１の時間が経過して、基準信号に代わり変調信号が入力されるが、このときレベル可変手段は基準信号によって校正された利得あるいは減衰量に固定されているので、過大な変調信号が出力されることはない。 With this configuration, in the signal generation device of the present invention, when the modulation signal is changed, a reference signal serving as a reference of the modulation signal that is changed with a constant amplitude is input to the level variable means for the first time, Loop control is performed so that the detection output for the reference signal becomes equal to the level setting voltage, and the voltage of the output signal of the first low-pass filter at that time is held and stored as the first reference voltage. Here, since the reference signal is unmodulated, the time constant required for the first low-pass filter can be very small, so the time required to obtain the first reference voltage, that is, the first There is little time. Then, after this first time has passed, a modulation signal is input instead of the reference signal. At this time, the level variable means is fixed to the gain or attenuation calibrated by the reference signal, so that excessive modulation is performed. No signal is output.

また、第１の時間が経過してからさらに第２の時間が経過すると、時定数が大きく変調の影響を受けない第２の低域通過フィルタの出力が第２基準電圧として保持記憶され、以後、この第２基準電圧と第２の低域通過フィルタの出力との差が検出され、その差に応じた第２の誤差信号と第１基準電圧との加算値によってレベル可変手段の利得あるいは減衰量の制御がなされる。 When the second time further elapses after the first time elapses, the output of the second low-pass filter that has a large time constant and is not affected by the modulation is held and stored as the second reference voltage. The difference between the second reference voltage and the output of the second low-pass filter is detected, and the gain or attenuation of the level varying means is determined by the added value of the second error signal and the first reference voltage corresponding to the difference. The amount is controlled.

したがって、変調信号の切り替え時に過大なレベルの信号を出力することがなく、また、変調信号を出力しているときでも、環境変化等の影響による出力信号のレベル変動を防ぐことができ、高い再現性で精度の高い測定を行うことができる。 Therefore, an excessive level signal is not output when the modulation signal is switched, and even when the modulation signal is output, the output signal level fluctuation due to the influence of environmental change or the like can be prevented, and high reproduction is achieved. Measurement with high accuracy.

以下、図面に基づいて本発明の実施の形態を説明する。
図１は、本発明を適用した信号発生装置２０の構成を示している。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the configuration of a signal generator 20 to which the present invention is applied.

図１において、信号発生手段２１は、定常時には、図示しない操作部等によって入力された出力信号指定情報Ｍに含まれるキャリア周波数情報、変調周波数情報および変調波形情報に応じて振幅変調された変調信号Ｓｍ（ｔ）を出力し、その変調信号Ｓｍ（ｔ）が変更されるときに、新たな変調信号の出力レベルの基準となる振幅一定の基準信号Ｓｒ（ｔ）を第１の時間Ｔ１（例えば数ミリ秒の短時間）だけ出力し、第１の時間Ｔ１が経過した後に、基準信号Ｓｒ（ｔ）に代わって、変更された変調信号を出力するように構成されている。 In FIG. 1, the signal generating means 21 is a modulated signal that is amplitude-modulated in accordance with carrier frequency information, modulation frequency information, and modulation waveform information included in output signal designation information M input by an operation unit (not shown) or the like in a steady state. When Sm (t) is output and the modulation signal Sm (t) is changed, a reference signal Sr (t) having a constant amplitude, which serves as a reference for the output level of the new modulation signal, is used for a first time T1 (for example, (Short time of several milliseconds), and after the first time T1 has elapsed, the modified modulation signal is output instead of the reference signal Sr (t).

ここで、基準信号Ｓｒ（ｔ）のレベルは変調信号の基準レベルと等しく、基本的には固定であり、後述するレベル可変手段２４が減衰器の場合、出力信号指定情報Ｍに含まれる出力レベル情報に対応したレベルに対して、レベル可変手段２４の減衰量の可変のための余裕分と後述する分岐手段２５の分岐損失を見込んだ値に設定されている。 Here, the level of the reference signal Sr (t) is equal to the reference level of the modulation signal and is basically fixed. When the level varying means 24 described later is an attenuator, the output level included in the output signal designation information M The level corresponding to the information is set to a value that allows for a margin for changing the attenuation amount of the level variable means 24 and a branch loss of the branch means 25 described later.

信号発生手段２１の構成は種々考えられ、図２〜図４にその構成例を示す。
図２の信号発生手段２１は、ベースバンド信号発生部２１ａから出力される変調用のベースバンド信号ｍとキャリア信号発生部２１ｂから出力されるキャリア信号Ｃａとを振幅変調器２１ｃに入力し、振幅変調器２１ｃにおいて、キャリア信号Ｃａの振幅をベースバンド信号ｍの振幅に応じて線形的に変化させて、変調信号Ｓｍ（ｔ）を生成する。また、基準信号発生手段２１ｄから新たな変調信号の出力レベルの基準となる振幅一定の基準信号Ｓｒ（ｔ）を発生させ、両信号を信号切替手段２１ｅに入力して、その一方を選択的に出力させる。 Various configurations of the signal generating means 21 are conceivable, and examples of the configuration are shown in FIGS.
The signal generator 21 in FIG. 2 inputs the modulation baseband signal m output from the baseband signal generator 21a and the carrier signal Ca output from the carrier signal generator 21b to the amplitude modulator 21c, and outputs the amplitude. In the modulator 21c, the amplitude of the carrier signal Ca is linearly changed according to the amplitude of the baseband signal m to generate a modulation signal Sm (t). Further, a reference signal Sr (t) having a constant amplitude that serves as a reference for the output level of a new modulation signal is generated from the reference signal generating means 21d, both signals are input to the signal switching means 21e, and one of them is selectively selected. Output.

また、最も単純な振幅変調（ＡＭ変調）の場合、図３に示す信号発生手段のように、ベースバンド信号発生部２１ａから出力される変調用のベースバンド信号ｍとキャリア信号発生部２１ｂから出力されるキャリア信号Ｃａとを振幅変調器２１ｃに入力し、振幅変調器２１ｃにおいて、キャリア信号Ｃａの振幅をベースバンド信号ｍの振幅に応じて線形的に変化させて、変調信号Ｓｍ（ｔ）を生成する。 In the case of the simplest amplitude modulation (AM modulation), the baseband signal m for modulation output from the baseband signal generation unit 21a and the output from the carrier signal generation unit 21b as in the signal generation unit shown in FIG. Is input to the amplitude modulator 21c. In the amplitude modulator 21c, the amplitude of the carrier signal Ca is linearly changed according to the amplitude of the baseband signal m, and the modulation signal Sm (t) is changed. Generate.

そして、この変調信号Ｓｍ（ｔ）の基準レベルはキャリア信号Ｃａのレベルであるから、信号切替手段２１ｆからの信号切替の指示によって、ベースバンド信号発生部２１ａから出力される信号をゼロにすることで、キャリア信号Ｃａを振幅変調器２１ｃから基準信号Ｓｒ（ｔ）として出力させることができる。この場合、キャリア信号発生部２１ｂが基準信号発生手段を構成することになる。 Since the reference level of the modulation signal Sm (t) is the level of the carrier signal Ca, the signal output from the baseband signal generator 21a is set to zero by the signal switching instruction from the signal switching means 21f. Thus, the carrier signal Ca can be output from the amplitude modulator 21c as the reference signal Sr (t). In this case, the carrier signal generator 21b constitutes a reference signal generator.

また、図４に示す信号発生手段２１のように、ベースバンド信号発生部２１ｇから出力される直交変調用のベースバンド信号(Ｉ，Ｑ)を直交変調器２１ｈに入力し直交変調信号Ｓｍ（ｔ）を生成する構成のものでは、ベースバンド信号発生部２１ｇが信号切替手段２１ｉからの信号切替の指示を受けてベースバンド信号(Ｉ，Ｑ)の代わりに、９０度位相が異なる２相の正弦波信号(cos
ω_ｓｔ，sin ω_ｓｔ)を直交変調器２１ｈに入力させることで、直交変調器２１ｈから振幅一定の基準信号Ｓｒ（ｔ）を出力することができる。 Further, as in the signal generating means 21 shown in FIG. 4, the quadrature modulation baseband signal (I, Q) output from the baseband signal generation unit 21g is input to the quadrature modulator 21h and the quadrature modulation signal Sm (t ), The baseband signal generator 21g receives a signal switching instruction from the signal switching means 21i, and instead of the baseband signal (I, Q), a two-phase sine having a phase difference of 90 degrees. Wave signal (cos
By inputting (ω _s t, sin ω _s t) into the quadrature modulator 21h, the reference signal Sr (t) having a constant amplitude can be output from the quadrature modulator 21h.

ここで、直交変調器２１ｈは、位相が９０度異なる２相のキャリア信号(cos ω_ｃｔ，sin
ω_ｃｔ)を有しており、入力されるベースバンド信号（Ｉ，Ｑ）に対して、
Ｓｍ（ｔ）＝Ｉ・sin ω_ｃｔ＋Ｑ・cos ω_ｃｔ
で表される変調信号Ｓｍ（ｔ）を出力する。 Here, the orthogonal modulator 21h are phase 90 degrees from the two-phase carrier signal (cos ω _c t, sin
ω _c t) and for the input baseband signal (I, Q),
Sm (t) = I · sin ω _c t + Q · cos ω _c t
The modulation signal Sm (t) represented by

また、ベースバンド信号（Ｉ，Ｑ）の代わりに正弦波信号(cos ω_ｓｔ，sin ω_ｓｔ)が入力された場合には、
Ｓｒ（ｔ）＝cos ω_ｓｔ・sin ω_ｃｔ＋sin
ω_ｓｔ・cos ω_ｃｔ
＝sin （ω_ｃｔ＋ω_ｓｔ）
で表される基準信号Ｓｒ（ｔ）を出力することになる。 Further, when the sinusoidal signal _{(cos ω s t, sin ω} s t) is input instead of the baseband signal (I, Q) is,
_{Sr (t) = cos ω s} t · sin ω c t + sin
ω _s t ・ cos ω _c t
_{= Sin (ω c t + ω} s t)
The reference signal Sr (t) represented by

レベル可変手段２４は、入力される制御信号Ｃに応じて減衰量または増幅度が可変され、信号発生手段２１から出力された信号Ａのレベルを可変して分岐手段２５に出力する。このレベル可変手段２４は、減衰器、増幅器あるいはそれらを組合せた構成のいずれでもよいが、ここでは制御信号Ｃの電圧が高いほど減衰量が小さくなる減衰器の場合で説明する。 The level varying unit 24 varies the attenuation amount or the amplification degree according to the input control signal C, varies the level of the signal A output from the signal generating unit 21, and outputs it to the branching unit 25. The level variable means 24 may be an attenuator, an amplifier, or a combination of them. Here, the level variable means 24 will be described in the case of an attenuator where the amount of attenuation decreases as the voltage of the control signal C increases.

分岐手段２５は、レベル可変手段２４の出力信号Ｂを２信号Ｄａ、Ｄｂに分岐し、その一方Ｄａを検波手段２６に出力し、他方Ｄｂを信号出力端子２０ａに出力する。 The branching unit 25 branches the output signal B of the level varying unit 24 into two signals Da and Db, one of which is output to the detecting unit 26 and the other of which is output to the signal output terminal 20a.

検波手段２６は例えばダイオード検波器によって構成され、レベル可変手段２４の出力信号Ｄａを検波する。この検波出力Ｅは、第１の比較手段２７および後述する第２のＬＰＦ（低域通過フィルタ）３１に入力される。 The detection means 26 is constituted by a diode detector, for example, and detects the output signal Da of the level variable means 24. This detection output E is input to the first comparison means 27 and a second LPF (low pass filter) 31 described later.

第１の比較手段２７は、例えば利得が極めて大きいアナログの差動増幅器からなり、検波出力Ｅと予め設定されているレベル設定電圧Ｖｓとを比較し、その差を表す第１の誤差信号Ｇを第１のＬＰＦ（低域通過フィルタ）２９に出力する。 The first comparison means 27 is composed of, for example, an analog differential amplifier having a very large gain, compares the detection output E with a preset level setting voltage Vs, and generates a first error signal G representing the difference. Output to a first LPF (low-pass filter) 29.

なお、このレベル設定電圧Ｖｓは、出力信号指定情報Ｍに含まれる出力レベル情報を受けたＤ／Ａ変換器２８から出力される。 The level setting voltage Vs is output from the D / A converter 28 that has received the output level information included in the output signal designation information M.

第１のＬＰＦ２９は、前記第１の時間Ｔ１より短い時定数（例えば、０．５〜１ミリ秒）を有し、第１の比較手段２７から出力された第１の誤差信号Ｇを受けてその時定数に対応した第１の遮断周波数Ｆａ（例えば１〜２ｋＨｚ）以下の信号成分Ｈを通過させ、第１の保持手段３０および後述するレベル制御手段４０に出力する。 The first LPF 29 has a time constant (for example, 0.5 to 1 millisecond) shorter than the first time T1, and receives the first error signal G output from the first comparison means 27. A signal component H having a frequency equal to or lower than the first cutoff frequency Fa (for example, 1 to 2 kHz) corresponding to the time constant is passed and output to the first holding unit 30 and a level control unit 40 described later.

第１の保持手段３０は、例えばアナログのサンプルホールド回路を含む回路で構成され、信号発生手段２１から基準信号Ｓｒ（ｔ）が出力されてから第１の時間Ｔ１が経過する直前に第１のＬＰＦ２９から出力されている信号Ｈの電圧を第１基準電圧Ｖｒ１として記憶保持し、これを後述するレベル制御手段４０に出力する。 The first holding unit 30 is constituted by a circuit including an analog sample-and-hold circuit, for example, and the first holding unit 30 outputs the first time T1 immediately after the reference signal Sr (t) is output from the signal generating unit 21. The voltage of the signal H output from the LPF 29 is stored and held as the first reference voltage Vr1, and this is output to the level control means 40 described later.

一方、第２のＬＰＦ３１は、第１のＬＰＦ２９の時定数に比べて格段に大きい時定数（例えば数１００秒）を有し、検波手段２６の出力Ｅを受けて第１の遮断周波数Ｆａより低く且つ変調信号Ｓｍ（ｔ）の変調周波数Ｆｍより低い第２の遮断周波数Ｆｂ（例えば０．０１Ｈｚ）以下の信号成分Ｊを通過させ、これをＡ／Ｄ変換器３２に出力する。 On the other hand, the second LPF 31 has a time constant (for example, several hundred seconds) that is significantly larger than the time constant of the first LPF 29, and receives the output E of the detection means 26 and is lower than the first cutoff frequency Fa. In addition, the signal component J having a frequency equal to or lower than the second cutoff frequency Fb (for example, 0.01 Hz) lower than the modulation frequency Fm of the modulation signal Sm (t) is passed and output to the A / D converter 32.

Ａ／Ｄ変換器３２は、第２のＬＰＦ３１の出力信号Ｊを所定周期（例えば１秒）でサンプリングしてデジタル値に変換して、第２の保持手段３３および第２の比較手段３４に出力する。 The A / D converter 32 samples the output signal J of the second LPF 31 at a predetermined period (for example, 1 second), converts it to a digital value, and outputs it to the second holding means 33 and the second comparison means 34. To do.

第２の保持手段３３は、信号発生手段２１から基準信号Ｓｒ（ｔ）が出力されてから第１の時間Ｔ１が経過し、さらに第２のＬＰＦ３１の時定数に応じた第２の時間Ｔ２（例えば１２０秒）が経過したときに、第２のＬＰＦ３１から出力されている信号Ｊの電圧（Ａ／Ｄ変換器３２の出力値）を第２基準電圧Ｖｒ２として記憶保持する。 The second holding means 33 passes the first time T1 after the reference signal Sr (t) is output from the signal generating means 21, and further, the second time T2 (in accordance with the time constant of the second LPF 31). For example, when 120 seconds elapses, the voltage of the signal J output from the second LPF 31 (the output value of the A / D converter 32) is stored and held as the second reference voltage Vr2.

また、第２の比較手段３４は、例えばディジタルのコンパレータによって構成され、第２の保持手段３３に第２基準電圧Ｖｒ２が保持された後に第２のＬＰＦ３１から出力される信号Ｊ（Ａ／Ｄ変換器３２の出力値）と第２基準電圧Ｖｒ２とを所定時間Ｔ３毎に比較し、その差に応じた第２の誤差信号Ｋをレベル制御手段４０に出力する。 The second comparison means 34 is constituted by, for example, a digital comparator, and a signal J (A / D conversion) output from the second LPF 31 after the second reference voltage Vr2 is held in the second holding means 33. And the second reference voltage Vr2 are compared every predetermined time T3, and a second error signal K corresponding to the difference is output to the level control means 40.

この第２の比較手段３４が出力する第２の誤差信号Ｋは、第２のＬＰＦ３１の出力Ｊと第２基準電圧Ｖｒ２との大小比較結果を示す場合と、その差分値を示す信号の場合のいずれでもよい。 The second error signal K output from the second comparison means 34 is a signal indicating the magnitude comparison result between the output J of the second LPF 31 and the second reference voltage Vr2, and a signal indicating the difference value. Either is acceptable.

大小比較結果を表す場合、例えば出力Ｊが第２基準電圧Ｖｒ２より大きいとき「１０」、出力Ｊが第２基準電圧Ｖｒ２より小さいとき「０１」、出力Ｊが第２基準電圧Ｖｒ２に等しいとき「１１」の２ビット信号を第２の誤差信号Ｋとして出力する。 When representing the magnitude comparison result, for example, “10” when the output J is larger than the second reference voltage Vr2, “01” when the output J is smaller than the second reference voltage Vr2, and “when the output J is equal to the second reference voltage Vr2”. 11 "is output as the second error signal K.

また、差分値を表す場合、出力Ｊと第２基準電圧Ｖｒ２の差の電圧値（Ｊ−Ｖｒ）を第２の誤差信号Ｋとして出力する。 When the difference value is expressed, the voltage value (J−Vr) of the difference between the output J and the second reference voltage Vr2 is output as the second error signal K.

レベル制御手段４０は、信号発生手段２１から基準信号Ｓｒ（ｔ）が出力されてから第１の時間Ｔ１が経過するまでの間は、第１のＬＰＦ２９の出力信号Ｈを制御信号Ｃとしてレベル可変手段２４に与えて、基準信号Ｓｒに対する検波手段２６の出力信号Ｅの電圧がレベル設定電圧Ｖｓに等しくなるように制御するフィードバックループを形成する。 The level control means 40 is variable in level by using the output signal H of the first LPF 29 as the control signal C until the first time T1 elapses after the reference signal Sr (t) is output from the signal generation means 21. A feedback loop is formed which is supplied to the means 24 and is controlled so that the voltage of the output signal E of the detection means 26 with respect to the reference signal Sr becomes equal to the level setting voltage Vs.

また、第１の時間Ｔ１が経過してから第２の時間Ｔ２が経過するまでの間は、第１基準電圧Ｖｒ１を制御信号Ｃとしてレベル可変手段２４に与えて、変更された変調信号Ｓｍ（ｔ）に固定の減衰量を与えて出力させる。 In addition, the first reference voltage Vr1 is applied as the control signal C to the level variable means 24 until the second time T2 elapses after the first time T1 elapses, and the modified modulation signal Sm ( A fixed attenuation is given to t) and output.

また、第２の時間Ｔ２が経過した後には、第２の誤差信号Ｋに対応した誤差電圧Ｖｅと第１基準電圧Ｖｒ１とを加算し、その加算結果を制御信号Ｃとしてレベル可変手段２４に与え、変更された変調信号Ｓｍ（ｔ）の温度変化等による出力レベルの変動を抑制制御するフィードバックループを形成する。 After the second time T2 has elapsed, the error voltage Ve corresponding to the second error signal K and the first reference voltage Vr1 are added, and the addition result is given to the level variable means 24 as a control signal C. A feedback loop is formed that suppresses and controls fluctuations in the output level due to a temperature change or the like of the changed modulation signal Sm (t).

図５は、前記したように、第２の誤差信号Ｋが出力Ｊと第２基準電圧Ｖｒ２との大小比較結果を表している場合に対応したレベル制御手段４０の構成例を示している。 FIG. 5 shows a configuration example of the level control means 40 corresponding to the case where the second error signal K represents the magnitude comparison result between the output J and the second reference voltage Vr2, as described above.

この図５に示すレベル制御手段４０では、第２の比較手段３４から、出力Ｊが第２基準電圧Ｖｒ２より大きいという比較結果を受けたき「１」、出力Ｊが第２基準電圧Ｖｒ２より小さいという比較結果を受けたき「−１」、出力Ｋが第２基準電圧Ｖｒ２に等しいという比較結果を受けたき「０」の各値を累積手段４１が順次累積し、その累積結果Ｕに対して所定の電圧ΔＶを乗算手段４２によって乗算し、その乗算結果を誤差電圧Ｖｅとし、これをＤ／Ａ変換器４３によってアナログの電圧に変換して加算手段４４で第１基準電圧Ｖｒ１と加算し、その加算結果を制御信号Ｃとしてスイッチ４５を介して出力する。 In the level control means 40 shown in FIG. 5, when the comparison result that the output J is larger than the second reference voltage Vr2 is received from the second comparison means 34, the output J is smaller than the second reference voltage Vr2. The accumulating means 41 sequentially accumulates each value of “−1” when receiving the comparison result and “0” when receiving the comparison result that the output K is equal to the second reference voltage Vr 2, The voltage ΔV is multiplied by the multiplication means 42, and the multiplication result is used as an error voltage Ve. This is converted into an analog voltage by the D / A converter 43 and added to the first reference voltage Vr1 by the addition means 44. The result is output as a control signal C through the switch 45.

スイッチ４５には、加算手段４４の出力の他に、第１のＬＰＦ２９の出力信号Ｈおよび第１基準電圧Ｖｒ１が入力されており、スイッチ制御手段４６は、信号発生手段２１から基準信号Ｓｒ（ｔ）が出力されてから第１の時間Ｔ１が経過するまでの間は、第１のＬＰＦ２９の出力信号Ｈを制御信号Ｃとして選択し、第１の時間Ｔ１が経過してから第２の時間Ｔ２が経過するまでの間は、第１基準電圧Ｖｒ１を制御信号Ｃとして選択し、第２の時間Ｔ２経過後は、加算手段４４の出力を制御信号Ｃとして選択して、レベル可変手段２４に入力させる。 In addition to the output of the adding means 44, the switch 45 receives the output signal H of the first LPF 29 and the first reference voltage Vr1, and the switch control means 46 receives the reference signal Sr (t from the signal generating means 21. ) Is output until the first time T1 elapses, the output signal H of the first LPF 29 is selected as the control signal C, and the second time T2 elapses after the first time T1 elapses. Until the first time elapses, the first reference voltage Vr1 is selected as the control signal C, and after the second time T2, the output of the adding means 44 is selected as the control signal C and input to the level variable means 24. Let

図６は、第２の誤差信号Ｋが出力Ｊと第２基準電圧Ｖｒ２との差分値を表している場合に対応したレベル制御手段４０の構成例を示している。 FIG. 6 shows a configuration example of the level control means 40 corresponding to the case where the second error signal K represents the difference value between the output J and the second reference voltage Vr2.

図６に示すレベル制御手段４０では、乗算手段４７によって第２の誤差信号Ｋに１以下の係数αを乗じ、その乗算結果を誤差電圧Ｖｅとし、これをＤ／Ａ変換器４３によってアナログの電圧に変換して加算手段４４で第１基準電圧Ｖｒ１と加算し、その加算結果をスイッチ４５を介して制御信号Ｃとして出力する。 In the level control means 40 shown in FIG. 6, the multiplication means 47 multiplies the second error signal K by a coefficient α of 1 or less, and the multiplication result is an error voltage Ve, which is converted into an analog voltage by the D / A converter 43. Is added to the first reference voltage Vr1 by the adding means 44, and the addition result is output as the control signal C via the switch 45.

上記構成例で、電圧ΔＶおよび係数αは、変調信号出力時のレベル変動に対する応答感度を決定する値であるが、この値を過大にすると過剰制御となって振動する場合があり、また、過小にするとレベル変動に追いつけなくなるので、振動が発生しない範囲でレベル変動を速やかに抑制できる適正な値に設定しておく。 In the above configuration example, the voltage ΔV and the coefficient α are values that determine the response sensitivity to the level fluctuation at the time of the modulation signal output. However, if this value is excessive, it may vibrate due to excessive control. Since it becomes impossible to catch up with the level fluctuation, it is set to an appropriate value that can quickly suppress the level fluctuation within a range in which vibration does not occur.

次に、この信号発生装置２０の動作を図７のフローチャートに基づいて説明する。
始めに、図示しない操作部や他の外部制御装置等によって出力信号指定情報Ｍが初期指定されると、出力信号指定情報Ｍに含まれる出力レベル情報に対応するレベル設定電圧Ｖｓが第１の比較手段２７に設定され、レベル可変手段２４に対する制御電圧Ｃが初期設定される（Ｓ１、Ｓ２）。 Next, the operation of the signal generator 20 will be described based on the flowchart of FIG.
First, when the output signal designation information M is initially designated by an operation unit (not shown) or other external control device, the level setting voltage Vs corresponding to the output level information included in the output signal designation information M is first compared. The control voltage C for the level variable means 24 is initially set (S1, S2).

また、信号発生手段２１（図２の構成の例で説明する）は、出力信号指定情報Ｍに含まれるキャリア周波数情報、変調周波数情報および変調波形情報に対応する変調信号Ｓｍ（ｔ）と、出力信号指定情報Ｍに応じた無変調の基準信号Ｓｒ（ｔ）とを生成する（Ｓ３）。 Further, the signal generating means 21 (described in the example of the configuration in FIG. 2) outputs a modulation signal Sm (t) corresponding to carrier frequency information, modulation frequency information and modulation waveform information included in the output signal designation information M, and an output. An unmodulated reference signal Sr (t) corresponding to the signal designation information M is generated (S3).

そして、所定タイミングに信号切替手段２１ｅによって基準信号Ｓｒ（ｔ）が選択され、且つ第１のＬＰＦ２９の出力信号Ｈが制御信号Ｃとしてレベル可変手段２４に入力される状態となる（Ｓ４）。 Then, the reference signal Sr (t) is selected by the signal switching unit 21e at a predetermined timing, and the output signal H of the first LPF 29 is input to the level varying unit 24 as the control signal C (S4).

このため、信号発生手段２１から出力された基準信号Ｓｒ（ｔ）はレベル可変手段２４により減衰を受けて分岐手段２５に入力され、その一方が検波手段２６で検波されて、その検波出力Ｅとレベル設定電圧Ｖｓとが第１の比較手段２７で比較され、その差分を示す第１の誤差信号Ｇが第１のＬＰＦ２９に入力され、その出力信号Ｈによってレベル可変手段２４の減衰量が可変されて、検波出力Ｅがレベル設定電圧Ｖｓに等しくなるように制御される。 Therefore, the reference signal Sr (t) output from the signal generating means 21 is attenuated by the level varying means 24 and input to the branching means 25, one of which is detected by the detecting means 26, and the detected output E is The level setting voltage Vs is compared by the first comparison means 27, the first error signal G indicating the difference is input to the first LPF 29, and the attenuation amount of the level variable means 24 is varied by the output signal H. Thus, the detection output E is controlled to be equal to the level setting voltage Vs.

このとき、第１のＬＰＦ２９の時定数は極めて短く、しかも、基準信号Ｓｒ（ｔ）は無変調で振幅一定であるため、第１のＬＰＦ２９から出力される信号Ｈ（制御信号Ｃ）は、検波出力Ｅの変化に速やかに追従変化し、レベル可変手段２４の減衰量は、第１の時間Ｔ１が経過する前に検波出力Ｅがレベル設定電圧Ｖｓにほぼ等しくなる状態まで追い込まれて安定し、第１の時間Ｔ１が経過する直前に第１基準電圧Ｖｒ１として第１の保持手段３０に保持される（Ｓ５、Ｓ６）。 At this time, since the time constant of the first LPF 29 is very short and the reference signal Sr (t) is unmodulated and has a constant amplitude, the signal H (control signal C) output from the first LPF 29 is detected. The amount of attenuation of the level varying means 24 is stabilized by being driven to a state where the detection output E becomes substantially equal to the level setting voltage Vs before the first time T1 elapses. Immediately before the first time T1 elapses, the first reference voltage Vr1 is held in the first holding means 30 (S5, S6).

そして、第１の時間Ｔ１が経過すると、信号切替手段２１ｅによって基準信号Ｓｒに代わり変調信号Ｓｍ（ｔ）が出力されるが、このときレベル可変手段２４への制御信号Ｃとして保持記憶された第１基準電圧Ｖｒ１に切り替わり、その減衰量は第１基準電圧Ｖｒ１に対応した値に固定される（Ｓ７）。 When the first time T1 elapses, the signal switching means 21e outputs the modulation signal Sm (t) instead of the reference signal Sr. At this time, the first signal stored and stored as the control signal C to the level variable means 24 is output. The reference voltage Vr1 is switched to, and the attenuation amount is fixed to a value corresponding to the first reference voltage Vr1 (S7).

したがって、この変調信号Ｓｍ（ｔ）の振幅が例えば最大値の状態で入力されたとしても、レベル可変手段２４の減衰量が適正値に固定設定されているので、出力端子２０ａから変調信号Ｓｍ（ｔ）の振幅変化量を超えるような過大な振幅の変調信号が出力されることはない。 Therefore, even if the amplitude of the modulation signal Sm (t) is input in a state of a maximum value, for example, the attenuation amount of the level variable means 24 is fixedly set to an appropriate value, so that the modulation signal Sm ( A modulation signal having an excessive amplitude exceeding the amplitude change amount of t) is not output.

この変調信号Ｓｍ（ｔ）に対する検波出力Ｅは、第２のＬＰＦ３１に入力され、その低周波成分が抽出されるが、第２のＬＰＦ３１の遮断周波数（第２周波数）は変調周波数に対して極めて低いので、第２のＬＰＦ３１からは検波出力Ｅを平均化した直流分のみが出力されることになる。 The detection output E with respect to the modulation signal Sm (t) is input to the second LPF 31 and its low frequency component is extracted. The cutoff frequency (second frequency) of the second LPF 31 is extremely low with respect to the modulation frequency. Since it is low, only the DC component obtained by averaging the detection output E is output from the second LPF 31.

この状態から、第２の時間Ｔ２が経過すると第２のＬＰＦ３１の出力が第２基準電圧Ｖｒ２として保持記憶される（Ｓ８、Ｓ９）。 When the second time T2 elapses from this state, the output of the second LPF 31 is held and stored as the second reference voltage Vr2 (S8, S9).

この第２基準電圧Ｖｒ２は、検波出力Ｅから変調信号Ｓｍ（ｔ）の振幅変調分が除かれて平均化された電圧の初期値を表している。 The second reference voltage Vr2 represents an initial value of an averaged voltage obtained by removing the amplitude modulation component of the modulation signal Sm (t) from the detection output E.

このようにして第２基準電圧Ｖｒ２が保持記憶された後は、第２のＬＰＦ３１の出力Ｊと第２基準電圧Ｖｒ２とが所定時間Ｔ３毎に比較され、その比較結果に応じた誤差電圧Ｖｅと第１基準電圧Ｖｒ１との加算値がレベル可変手段２４に与えられて、第２のＬＰＦ３１の出力Ｊを第２基準電圧Ｖｒ２に近づける方向に制御される（Ｓ１０、Ｓ１１）。 After the second reference voltage Vr2 is held and stored in this manner, the output J of the second LPF 31 and the second reference voltage Vr2 are compared every predetermined time T3, and the error voltage Ve corresponding to the comparison result is compared with the error voltage Ve. The added value with the first reference voltage Vr1 is given to the level varying means 24, and the output J of the second LPF 31 is controlled to approach the second reference voltage Vr2 (S10, S11).

このため、たとえ温度変化等の影響で、信号発生手段２１から出力される変調信号Ｓｍ（ｔ）のレベルやレベル可変手段２４の減衰量が変動して、第２のＬＰＦ３１の出力が変動しても、その変動を抑圧する方向に制御がなされるので、出力端子２０ａに出力される変調信号Ｓｍ（ｔ）のレベル変動も抑圧される。 For this reason, the level of the modulation signal Sm (t) output from the signal generating means 21 and the attenuation amount of the level variable means 24 fluctuate due to the influence of a temperature change or the like, and the output of the second LPF 31 fluctuates. However, since the control is performed in the direction of suppressing the fluctuation, the level fluctuation of the modulation signal Sm (t) output to the output terminal 20a is also suppressed.

また、この制御がなされている間に、出力信号指定情報Ｍが変更されると、処理１２に移行して、前記同様の処理がなされることになる（Ｓ１２）。 If the output signal designation information M is changed while this control is being performed, the process proceeds to process 12 and the same process as described above is performed (S12).

なお、この実施形態例では、第２のＬＰＦ３１の出力ＪをＡ／Ｄ変換器３２によってデジタル値に変換してから記憶保持および比較処理を行っているが、Ａ／Ｄ変換器３２を省略して第２の保持手段３３および比較手段３４をアナログ回路で構成してもよく、その場合には、前記したレベル制御手段４０のＤ／Ａ変換器４３も省略することができる。 In this embodiment, the output J of the second LPF 31 is converted into a digital value by the A / D converter 32 and then stored and compared, but the A / D converter 32 is omitted. The second holding means 33 and the comparing means 34 may be constituted by analog circuits. In this case, the D / A converter 43 of the level control means 40 can also be omitted.

本発明の実施形態の構成を示すブロック図The block diagram which shows the structure of embodiment of this invention 実施形態の要部の構成例を示す図The figure which shows the structural example of the principal part of embodiment. 実施形態の要部の構成例を示す図The figure which shows the structural example of the principal part of embodiment. 実施形態の要部の構成例を示す図The figure which shows the structural example of the principal part of embodiment. 実施形態の要部の構成例を示す図The figure which shows the structural example of the principal part of embodiment. 実施形態の要部の構成例を示す図The figure which shows the structural example of the principal part of embodiment. 実施形態の動作を説明するためのフローチャートFlowchart for explaining the operation of the embodiment 従来装置の構成例を示す図Diagram showing a configuration example of a conventional device

Explanation of symbols

２０……信号発生装置、２１……信号発生手段、２１ａ、２１ｇ……ベースバンド信号発生部、２１ｂ……キャリア信号発生部、２１ｃ……振幅変調器、２１ｄ……基準信号発生手段、２１ｅ、２１ｆ、２１ｉ……信号切替手段、２１ｈ……直交変調器、２４……レベル可変手段、２５……分岐手段、２６……検波手段、２７……第１の比較手段、２８……Ｄ／Ａ変換器、２９……第１のＬＰＦ（低域通過フィルタ）、３０……第１の保持手段、３１……第２のＬＰＦ（低域通過フィルタ）、３２……Ａ／Ｄ変換器、３３……第２の保持手段、３４……第２の比較手段 DESCRIPTION OF SYMBOLS 20 ... Signal generator, 21 ... Signal generator, 21a, 21g ... Baseband signal generator, 21b ... Carrier signal generator, 21c ... Amplitude modulator, 21d ... Reference signal generator, 21e, 21f, 21i: Signal switching means, 21h: Quadrature modulator, 24: Level variable means, 25: Branch means, 26: Detection means, 27: First comparison means, 28: D / A Converter 29... First LPF (low pass filter) 30... First holding means 31... Second LPF (low pass filter) 32 .. A / D converter 33 ... Second holding means, 34 ... Second comparing means

Claims

A modulated signal that is amplitude-modulated is output in a steady state, and when the modulated signal is changed, a reference signal having a constant amplitude that serves as a reference for the output level of the modulated signal is output for a first time. Signal generating means (21) for outputting the modified modulation signal after a lapse of time;
Level variable means (24) in which the amount of attenuation or the degree of amplification can be varied in order to vary and output the level of the output signal of the signal generating means in accordance with the input control signal;
Branching means (25) for branching the output signal of the level varying means;
Detection means (26) for detecting one signal (Da) branched by the branch means;
A first comparison means (27) for comparing the output signal of the detection means with a preset level setting voltage (Vs) and outputting a first error signal (G) which is the difference between the output signal and the level setting voltage (Vs);
A first low-pass filter (29) for receiving a first error signal output from the first comparing means and passing a signal component of a first frequency or lower;
The voltage (H) of the signal output from the first low-pass filter is stored as a first reference voltage immediately before the first time elapses after the signal generating means outputs the reference signal. First holding means (30) to perform,
A second low-pass filter (31) that receives the output signal of the detection means and passes a signal component that is lower than the first frequency and lower than the modulation frequency of the modulation signal;
When the first time has elapsed since the signal generating means output the reference signal, and when the second time corresponding to the time constant of the second low-pass filter has elapsed, the second time Second holding means (33) for storing and holding the voltage of the signal output from the low-pass filter as a second reference voltage;
A signal output from the second low-pass filter after the second reference voltage is held in the second holding means is compared with the second reference voltage, and a second error corresponding to the difference is compared. Second comparing means (34) for outputting a signal;
The output signal of the first low-pass filter is given as a control signal to the level variable means until the first time elapses after the signal generating means outputs the reference signal, and the reference variable Drive-in control is performed so that the voltage of the output signal of the detection means with respect to the signal becomes equal to the level setting voltage, and the first time is elapsed until the second time elapses. The modulation signal changed by applying a reference voltage as a control signal to the level varying means is output with a fixed gain, and after the second time has elapsed, the first reference voltage, the second error signal, A signal generator comprising level control means (40) for suppressing fluctuations in the output level of the modulated signal that has been changed by giving a signal obtained by adding to the level variable means as a control signal.

The signal generating means (21)
A baseband signal generator (21a) for outputting a baseband signal;
A carrier signal generator (21b) for generating a carrier signal;
An amplitude modulator (21c) that linearly changes the amplitude of the carrier signal according to the voltage of the baseband signal and outputs the modulated signal;
Reference signal generating means (21d) for outputting the reference signal;
2. The signal generator according to claim 1, comprising signal switching means (21e) for selectively outputting the modulation signal and the reference signal.

The signal generating means (21)
A baseband signal generator (21a) for outputting a baseband signal;
A carrier signal generator (21b) for generating a carrier signal;
An amplitude modulator (21c) that linearly changes the amplitude of the carrier signal according to the voltage of the baseband signal and outputs a modulated signal;
When generating the reference signal, a signal switching means for controlling the amplitude signal to be output by outputting a signal for making the output voltage of the baseband signal constant to the baseband signal generation unit. 21f). The signal generator according to claim 1, wherein:

The signal generating means (21)
Baseband signals (I, Q) and 90 ° phase difference two-phase sinusoidal signals _{_{(cos ω s t, sinω s}} t) baseband signal generator for outputting selectively the the (21g),
A quadrature modulator (21h) that outputs a modulation signal in accordance with the baseband signal;
A signal switching means (21i) for controlling the baseband signal generator to output a signal for outputting the sine wave signal so that the quadrature modulator outputs the reference signal when generating the reference signal; The signal generator according to claim 1, comprising:

An A / D converter (32) that converts the signal component (J) that has passed through the second low-pass filter into a digital signal and outputs the digital signal to the second holding means and the second comparing means;
The second comparing means outputs a magnitude comparison value between the second reference voltage and the converted digital signal,
The level control means (40)
Accumulating means (41) for sequentially accumulating the magnitude comparison values, multiplication means (42) for multiplying the accumulated magnitude comparison values by a predetermined voltage (ΔV) and outputting an error voltage, and converting the error voltage. D / A conversion means (43) for outputting the first analog voltage, and adding the first reference voltage and the error voltage converted to the first analog voltage to output a second analog voltage. It comprises an adding means (44) and a switch (45) for selecting any one of the front 1 reference voltage, the 2 reference voltage, or the second analog voltage and outputting it as the control signal. 5. The signal generator according to claim 1, wherein:

An A / D converter (32) that converts the signal component (J) that has passed through the second low-pass filter into a digital signal and outputs the digital signal to the second holding means and the second comparing means;
The second comparing means outputs a difference value between the second reference voltage and the converted digital signal,
The level control means (40)
A multiplication means (47) for multiplying the difference value by a predetermined coefficient (α) and outputting an error voltage; a D / A conversion means (43) for converting the error voltage and outputting a third analog voltage; An adding means (44) for adding the first reference voltage and the error voltage converted into the third analog voltage to output a fourth analog voltage; and the previous one reference voltage, the second reference voltage, or 5. The signal generator according to claim 1, further comprising a switch (45) for selecting any one of the fourth analog voltages and outputting the selected signal as the control signal.