JP6933604B2 - Phase characteristic calibration device and phase characteristic calibration method - Google Patents

Description

The present invention relates to a phase characteristic calibration device and a phase characteristic calibration method.

In order to improve the transmission speed of wireless communication, a communication method using a wide band modulated signal is being studied in the millimeter wave band, submillimeter wave band, and terahertz wave band, which have higher carrier frequencies than before. In the following explanation, the millimeter wave band, the submillimeter wave band, the terahertz wave band, and the like are collectively referred to as the millimeter wave band.

In the multi-level quadrature amplitude modulation method having high frequency utilization efficiency, a small phase error causes deterioration of transmission characteristics, so that it is required to measure the phase error of a wideband modulated signal with high accuracy. Generally, in a wideband signal measurement circuit used in the millimeter wave band, the phase characteristic of the frequency conversion unit in the measurement circuit cannot be ignored, so it is important to calibrate the phase characteristic of the wideband signal measurement circuit.

FIG. 10 shows a configuration example 1 of a phase characteristic calibration system as a related technique (see, for example, Non-Patent Document 1). This phase characteristic calibration system 100 calibrates the phase characteristic (phase frequency characteristic) of the millimeter wave band signal measurement unit 150, and includes a short pulse light source 111, an optical variable delay device 113, a synchronization processing unit 115, and the like. It includes a calibration signal generation unit 120, an electro-optical frequency conversion unit 130, and a phase difference calculation unit 140.

_{The short pulse light P 10} output by the short pulse light source 111 at a predetermined repetition frequency is sent to the optical variable delay device 113 via the optical branching device 112, delayed by the optical variable delay device 113, and is an electro-optical frequency converter. It is sent to the polarization separator 132 of 130. The light variable delay device 113 changes the light delay time by mechanically moving the position of the mirror 113a.

On the other hand, in the calibration signal generator 120, the intermediate frequency signal generated by the intermediate frequency signal generator 121 and the CW (Continuous Wave) locally generated signal generated by the local signal generator 122 are combined with the frequency converter 123. The intermediate frequency signal is frequency-converted (up-converted) into a millimeter wave band _{and output as a calibration signal Er} from the horn antenna 124 to the electro-optical crystal 131. At that time, the intermediate frequency signal and the local signal are synchronized with the repetition frequency of the short pulse light source 111 by the synchronization processing unit 115, whereby the calibration signal _{Er in the millimeter wave band synchronized with the repetition frequency of the short pulse light source 111.} Is obtained.

Specifically, a phase-locked loop (PLL) circuit is used to give a sampling clock that is an integral multiple of the repetition frequency of the short pulse light source 111 to the D / A converter of the intermediate frequency signal generator 121, and to generate a local signal. The reference frequency of the local signal generator 122 is controlled so that the frequency is an integral multiple of the repetition frequency of the short pulse light source 111. By appropriately setting the period of the digital data given to the D / A converter so that the frequency of the intermediate frequency signal is an integral multiple of the repetition frequency of the short pulse light source 111, the frequency of the calibration signal is the repetition of the short pulse light source 111. An integral multiple of the frequency, that is, the repetition period of the short pulse light source 111 is an integral multiple of the period of the calibration signal.

In the electro-optical frequency conversion unit 130, _{the electric field of the calibration signal Er} is applied to the electro-optical crystal 131, and the short pulse light P ₁₁ from the optical variable delay device 113 is transmitted through the polarization separator 132 to the electro-optical crystal 131. The short pulsed light input to and reflected at the tip of the electro-optical crystal 131 is input to the receiver 133 via the polarization separator 132 (see, for example, Non-Patent Document 2). Specifically, when an electric field is applied to the electro-optical crystal 131, the polarization of the reflected light from the electro-optical crystal 131 changes due to the electro-optical effect, and the polarization of the reflected light is polarized by the polarization separator 132 and the receiver 133. It is designed to detect changes in.

The electric signal output from the receiver 133 is proportional to the electric field applied to the electro-optical crystal 131 and also to the optical power of the reflected light from the electro-optical crystal 131. Therefore, an electric signal proportional to the product of the electric field of the _{calibration signal Er and the optical power of the short pulse light P 11} is output, and the low-speed receiver 133 detects only the low frequency component. It has the same function as a mixer that frequency-converts (down-converts) the millimeter-wave band calibration signal _Er into a low-frequency electric signal E _10.

When sufficiently shorter than the inverse of the maximum frequency of the short pulse light P ₁₁ pulse width calibration signal E _r of the electrical electrical signals E ₁₀ outputted from the optical frequency conversion unit 130, calibration signal E _r short optical pulses P ₁₁ It will be sampled at the repetition cycle of. For the repetition period of the short-pulse light source 111 is an integer multiple of the period of the calibration signal E _r, it will sample repeatedly particular point repeating waveform of the calibration signal E _r. By varying the delay time of the optical variable delay unit 113, since the time of sampling the calibration signal E _r with pulsed light P ₁₁ is changed, the output from the electro-optical frequency conversion unit 130 while changing the delay time of the optical variable delay unit 113 When the electric signal E _{10 is recorded, the time waveform of the calibration signal Er} in the millimeter wave band can be measured by the low-speed receiver 133. The time waveform of the calibration signal _Er is converted into a frequency domain by performing signal processing such as Fourier transform in the phase difference calculation unit 140, and the phase characteristic is calculated.

The millimeter wave band signal measuring unit 150 includes a local signal generator 152 that generates a CW local signal, a frequency converter 151 such as a mixer, an intermediate frequency signal measuring device 153 such as an A / D converter, and a phase. A corrector 154 is provided, and the calibration signal _Er or the signal to be measured in the millimeter wave band is frequency-converted (down-converted) into an intermediate frequency signal and converted into a digital signal. By analyzing this digital signal, it is possible to obtain measurement results such as Error Vector Magnitude (EVM).

_{The calibration signal Er} generated by the calibration signal generation unit 120 is sent to the millimeter wave band signal measurement unit 150 and input to the frequency converter 151, and the CW station transmission generated by the local signal generator 152 is transmitted. The number is input to the frequency converter 151. The calibration signal _Er is frequency-converted (down-converted) into an intermediate frequency signal by the frequency converter 151, and then converted into a digital signal by the intermediate frequency signal measuring instrument 153. The phase difference calculation unit 140 performs signal processing such as Fourier transform on this digital signal to convert it into a frequency domain and calculate the phase characteristics.

The phase characteristics of the calibration signal measured by the electro-optical frequency conversion unit 130 as described above, and the phase characteristics of the digital signal output from the intermediate frequency signal measuring instrument 153 by inputting the calibration signal to the millimeter-wave band signal measurement unit 150. Based on the above, the phase characteristic of the millimeter wave band signal measuring unit 150 itself is calculated and set in the phase corrector 154 as the phase correction value. When the signal to be measured is measured by the millimeter wave band signal measuring unit 150, the phase characteristic of the millimeter wave band signal measuring unit 150 is corrected by the phase corrector 154 and output as a measurement result.

Next, a method of calibrating the frequency characteristics of the amplitude and phase of the millimeter wave band signal measuring unit 150 will be described in more detail. The frequency characteristic (complex number including phase) of the calibration signal is _Xc (f), the frequency characteristic (complex number including phase) of the millimeter wave band signal measurement unit 150 is G (f), and the calibration signal is the millimeter wave band signal measurement unit 150. _{Let Y c} (f) be the frequency characteristic (complex number including phase) of the output signal from the intermediate frequency signal measuring instrument 153 at the time of input to. _{As described above, Xc} (f) is obtained from the time waveform of the calibration signal measured by inputting the calibration signal to the electro-optical frequency conversion unit 130, and the calibration signal is input to the millimeter-wave band signal measurement unit 150 for frequency conversion. _{Y c} (f) can be obtained from the waveform of the intermediate frequency signal, and G (f) can be obtained from the following equation (1).

ここで、ｆ_ＬＯはミリ波帯信号測定部１５０の局発信号の周波数である。

Here, f _LO is the frequency of the local signal of the millimeter wave band signal measuring unit 150.

The frequency characteristic (phase) of the output signal from the intermediate frequency signal measuring instrument 153 when the frequency characteristic (complex number including phase) of the signal to be measured is X (f) and the signal to be measured is input to the millimeter wave band signal measuring unit 150. Assuming that the complex number including) is Y (f), X (f) in which the frequency characteristic of the millimeter wave band signal measuring unit 150 is corrected can be obtained as a measurement result from the following equation (2).

FIG. 11 shows a configuration example 2 of another phase characteristic calibration system as a related technique (see, for example, Non-Patent Document 3). In this phase characteristic calibration system 200, a two-tone light source 211 is used instead of the short pulse light source 111 and the optical variable delayer 113 of the above configuration example 1, and the polarization separator 132 in the electro-optical frequency conversion unit 230 It is the same as the configuration example 1 of the phase characteristic calibration system 100 described above, except that the optical circulator 232 and the like are used instead, and the synchronization processing unit 115 is not connected to the calibration signal generation unit 220.

Next, the principle of frequency conversion in the phase characteristic calibration system 200 will be described.
FIG. 12 is an explanatory diagram showing the operation of the phase characteristic calibration system 200 of FIG. 11 by spectrum. _{FIG. 12 (a) shows the frequency component of the output light (two-tone light P 20} ) output from the two-tone light source 211, and FIG. 12 (b) shows the calibration signal _{Er output from the calibration signal generation unit 220. 12 (c) shows the frequency component of the optical signal P 21} input from the optical circulator 232 to the optical band path filter 233, and FIG. 12 (d) shows the frequency component of the optical signal P 21 and is output from the receiver 234. The frequency component of the electric signal E _{20 is shown.}

As shown in FIG. 12A, the two-tone light source 211 outputs two lights (two-tone light P _{20 ) having optical frequencies f 1} and f ₂ with the same polarization, and at this time, the difference between the two optical frequencies. Let f _L = f ₂ −f ₁ . _{The two-tone light P 20} output from the two-tone light source 211 is input to the electro-optical crystal 231 via the optical circulator 232, and the light reflected by the electro-optical crystal 231 is passed through the optical circulator 232 to the optical bandpass filter 233. Entered. On the other hand, as shown in FIG. 12 (b), the calibration signal generating unit 220, the carrier frequency _{f c,} the calibration signal _{E r} is a multi-tone signal having a frequency interval _{f m} is generated, the electro-optical via the horn antenna 224 It is sent to crystal 231.

When the electric field of the multitone signal from the calibration signal generation unit 220 is applied to the electro-optical crystal 231, _{a sideband wave is generated in the optical signal P 21} reflected by the electro-optical crystal 231 as shown in FIG. 12 (c). The relationship between the optical frequency difference f _L of the two-tone light P ₂₀ and the carrier frequency f _c of the calibration signal _{Er is set to f L} = f _c + f _IF , and the light _{near the optical frequency f 2} is extracted by the optical bandpass filter 233. If you enter the light receiver 234, and beat generated between the sideband in the vicinity of the optical and f ₂ of the optical frequency f _2, FIG. 12 (d), the center frequency is the frequency interval f _IF f _m (Intermediate frequency signal E ₂₀ ) is obtained.

Here, although ignored beat between sideband frequency interval f _m, it is possible to remove the beat component between sideband easily by the bandpass filter when properly setting the relationship between f _IF and f _m. As described above, the calibration signal E _r of the carrier frequency f _c is a center frequency is frequency-converted into an intermediate frequency signal E ₂₀ of f _IF.

Since the phase relationship between the multitones is maintained in the above frequency conversion, the intermediate frequency _fIF is set to a frequency band capable of A / D conversion, and the phase difference calculation unit 240 sets the intermediate frequency signal E ₂₀ to A / D. The phase difference between multitones can be calculated by conversion. Then, as in the configuration example 1 of the related technology described above, the phase characteristic measured by inputting the calibration signal to the electro-optical frequency conversion unit 230 and the phase measured by inputting the calibration signal to the millimeter-wave band signal measuring unit 250. From the characteristics, the phase correction value was obtained and set in the phase corrector 254 of the millimeter wave band signal measuring unit 250, and at the time of measurement, the measured signal was input to the millimeter wave band signal measuring unit 250 to calibrate the phase characteristics. The measurement result can be obtained.

Yukiyasu Kimura, Masaaki Fuse, Masanori Machidori, Takashi Mori, "Examination of Phase Calibration Method for Terahertz Wave Down Converter by Electro-Optical Sampling Method", Proceedings of the 2018 IEICE General Conference, BCI-1-7, 2018 A. Sasaki and T. Nagatsuma, "Millimeter-Wave Imaging Using an Electrooptic Detector as a Harmonic Mixer", IEEE Journal of Selected Topics in Quantum Electronics, vol. 6, no. 5, pp. 735-740, 2000 S. Hisatake, "Visualization of millimeter and terahertz waves based on photonics", 2016 IEEE International Topical Meeting on Microwave Photonics, pp. 73-74, 2016

However, in the phase characteristic calibration system of FIG. 10, it is necessary to sweep the optical variable delay device 113 in order to obtain the time waveform of the calibration signal. The optical variable delay device 113 has a mechanically movable part, and has problems such as being affected by mechanical vibration, having a limited operating speed, and having a short life. In particular, in order to improve the frequency resolution of phase calibration, it is necessary to lengthen the time span of the time waveform, that is, to lengthen the delay time of the optical variable delay device 113, so that the physical dimensions of the optical variable delay device 113 become large. There was a problem of getting bigger. Further, in order to increase the conversion efficiency of the electro-optical frequency conversion unit 130, it is necessary to increase the optical power of the short pulse light, but since it is a short pulse, the peak power becomes very large, and the pulse waveform is due to the non-linear effect of the optical fiber or the like. Is deformed, and there is a problem that the conversion characteristics of the electro-optical frequency conversion unit 130 change.

In the phase characteristic calibration system of FIG. 11, the problem of the optical variable delay device and the short pulse light does not occur, but the electro-optical frequency converter 230 down-converts the calibration signal and shifts the frequency as a whole. The frequency interval of the three continuous waves of the calibration signal does not change even after frequency conversion, and it is necessary to calculate the phase difference of the spectral components with a relatively wide frequency interval. Therefore, there is a problem that the phase measurement accuracy is deteriorated due to the influence of the frequency dependence of the phase of the receiver 234 and the electric circuit after that. Further, a receiver 234 having a relatively wide band and an A / D converter in the phase difference calculation unit 240 are required, and the sampling frequency of the A / D conversion becomes high and the amount of data increases. There is a problem that the amount is large and the device becomes expensive.

The present invention has been made to solve the above-mentioned problems, and provides an inexpensive phase characteristic calibration device and a phase characteristic calibration method capable of accurately calibrating the phase characteristics of a millimeter-wave band signal measurement circuit. The purpose is.

The phase characteristic calibrator according to claim 1 of the present invention is a phase characteristic calibrator (1) that calibrates the phase characteristics of the measurement circuit (50) in order to achieve the above object, and has three or more waves having different frequencies from each other. _{A generator (20) that generates a calibration signal (Er} ) in which continuous waves are combined, a first light in which three or more continuous lights having different frequencies are combined, and three waves of the first light. used above and the second generating unit and light for generating a synthesized local light (P _L) is a continuous light of less than or greater frequency than any frequency of the continuous light (10), said local light The frequency conversion unit (30) outputs an _{intermediate frequency signal (EIF} ) obtained by frequency-converting the calibration signal by the electro-optical effect and synthesizing three or more continuous waves in the intermediate frequency band, and the calibration signal 3 The frequency changing unit (70) that changes the frequency of continuous waves above the wave within a predetermined frequency band, and the first light and the first light according to the value of the frequency that is changed each time the frequency is changed by the frequency changing unit. The frequency interval with the second light is changed, the phase difference between three or more continuous waves of the intermediate frequency signal is calculated, and the first phase difference characteristic over the entire predetermined frequency band is acquired. At the same time, each time the frequency is changed by the frequency changing unit, the calibration signal is measured using the measuring circuit, and the phase difference between three or more continuous waves output from the measuring circuit is calculated. A calibration unit (40) that acquires the second phase difference characteristic over the entire predetermined frequency band and calibrates the phase characteristic of the measurement circuit based on the acquired first and second phase difference characteristics. The frequency of any of the three or more continuous waves of the intermediate frequency signal is lower than any of the frequencies of the three or more continuous waves of the calibration signal, and the three or more continuous waves of the calibration signal. The frequency interval of the first light is different from the frequency interval of three or more continuous lights of the first light, and the frequency interval of three or more continuous waves of the intermediate frequency signal is three or more waves of the calibration signal. It is characterized in that the calibration signal and the respective frequencies of the station emission are set so as to be narrower than the frequency interval of the continuous wave.

With this configuration, the phase characteristic calibration device according to claim 1 of the present invention does not use the optical variable delay device having the mechanically movable part as described in the configuration example 1 of FIG. 10, so that the mechanically movable part is not used. The phase characteristics can be calibrated with high frequency resolution without being restricted by. Further, since the short pulse light is not used as in the configuration example 1 of FIG. 10, the short pulse light waveform is not deformed and the conversion characteristics of the electro-optical frequency conversion unit are not changed.

Moreover, the phase characteristic calibration device according to claim 1 of the present invention is set so that the frequency interval of three or more continuous waves of the intermediate frequency signal is narrower than the frequency interval of three or more continuous waves of the calibration signal. Therefore, the band handled by the electric circuit can be narrowed as compared with the conventional case, so that the phase of the calibration signal can be measured with high accuracy using a low-speed A / D converter with a small amount of calculation. Therefore, the device price can be reduced.

In the phase characteristic calibration device according to claim 2 of the present invention, the generator (10) includes a first CW signal generator (11) that generates a first continuous wave signal and the first continuous wave signal. An optical comb generator (12) that generates optical combs having a plurality of optical spectrum components at intervals of frequencies of the above, an optical branching device (13) that splits the output light from the optical comb generator into two, and the above. A first optical bandpass filter (14) and a second optical bandpass filter (15) that extract different optical spectrum components from one and the other output light of the optical branching device, and a second continuous wave signal. The second continuous wave is generated by applying amplitude modulation or phase modulation to the output light of the second CW signal generator (16) and the second optical bandpass filter with the second continuous wave signal. An optical modulator (17) that generates a plurality of sideband waves at intervals of signal frequencies, and an optical combiner (18) that combines the output light of the first optical bandpass filter with the output light of the optical modulator. ) And.

With this configuration, the phase characteristic calibrator according to claim 2 of the present invention comprises a first light in which three or more continuous lights having different frequencies are combined, and a continuous light having three or more waves of the first light. It is possible to generate local emission in which a second light, which is continuous light having a frequency lower or higher than any frequency, is combined. Further, each time the frequency is changed by the frequency changing unit, the frequency interval between the first light and the second light can be changed continuously and over a wide range according to the value of the frequency to be changed.

In the phase characteristic calibrator according to claim 3 of the present invention, the first CW signal generator, the second CW signal generator, and the generator have the first frequency synchronized with a common reference frequency. The continuous wave signal, the second continuous wave signal, and the calibration signal are generated, and the frequencies of three or more continuous waves of the intermediate frequency signal are synchronized with the reference frequency, respectively. do.

With this configuration, the phase characteristic calibrator according to claim 3 of the present invention can obtain continuous waves of three or more waves in the intermediate frequency band without frequency error, and between three or more continuous waves in the intermediate frequency band in the calibration unit. The phase difference of can be easily calculated.

The phase characteristic calibration device according to claim 4 of the present invention amplifies a continuous wave of three or more waves of the intermediate frequency signal between the frequency conversion unit and the calibration unit to perform frequency conversion, and performs frequency conversion to the second intermediate frequency. It further has a second frequency conversion unit (60) that outputs a _{second intermediate frequency signal (EIF2} ) in which continuous waves of three or more waves in the band are combined, and the calibration unit replaces the intermediate frequency signal. The phase difference between the three or more continuous waves of the second intermediate frequency signal output from the second frequency conversion unit is calculated, and any frequency of the three or more continuous waves of the second intermediate frequency signal can be used. It is characterized in that it is set to be lower than any frequency of three or more continuous waves of the intermediate frequency signal.

With this configuration, the phase characteristic calibration device according to claim 4 of the present invention is provided with the second frequency conversion unit, so that the intermediate frequency band is set to a frequency at which the 1 / f noise of the electric circuit is reduced, and the second frequency band is provided. It can be converted to a sufficiently low second intermediate frequency band after being sufficiently amplified by the amplifier of the frequency conversion unit. As a result, it is possible to realize an inexpensive device by reducing the band and sampling speed of the A / D converter of the calibration unit while avoiding 1 / f noise of the electric circuit and maintaining a high S / N ratio.

The phase characteristic calibration device according to claim 5 of the present invention is characterized in that the second frequency converter is an orthogonal frequency converter (60A) that outputs an in-phase component and an orthogonal component of the second intermediate frequency signal. And.

With this configuration, the phase characteristic calibration device according to claim 5 of the present invention can prevent the backing of negative frequency components by the second frequency conversion unit.

The phase characteristic calibration device according to claim 6 of the present invention amplifies a continuous wave of three or more waves of the intermediate frequency signal between the frequency conversion unit and the calibration unit to perform frequency conversion, and performs frequency conversion to the second intermediate frequency. It further has a second frequency conversion unit (60) that outputs a _{second intermediate frequency signal (EIF2} ) in which continuous waves of three or more waves in the band are combined, and the calibration unit replaces the intermediate frequency signal. The phase difference between the three or more continuous waves of the second intermediate frequency signal output from the second frequency conversion unit is calculated, and any frequency of the three or more continuous waves of the second intermediate frequency signal can be used. It is characterized in that it is set to be lower than any frequency of three or more continuous waves of the intermediate frequency signal.

With this configuration, the phase characteristic calibrator according to claim 6 of the present invention is provided with the second frequency conversion unit, so that the intermediate frequency band is set to a frequency at which the 1 / f noise of the electric circuit is reduced, and the second frequency band is provided. It can be converted to a sufficiently low second intermediate frequency band after being sufficiently amplified by the amplifier of the frequency conversion unit. As a result, it is possible to realize an inexpensive device by reducing the band and sampling speed of the A / D converter of the calibration unit while avoiding 1 / f noise of the electric circuit and maintaining a high S / N ratio.

The phase characteristic calibration device according to claim 7 of the present invention is characterized in that the second frequency converter is an orthogonal frequency converter (60A) that outputs an in-phase component and an orthogonal component of the second intermediate frequency signal. And.

With this configuration, the phase characteristic calibration device according to claim 7 of the present invention can prevent the backing of negative frequency components by the second frequency conversion unit.

In the phase characteristic calibrator according to claim 8 of the present invention, the first CW signal generator, the second CW signal generator, and the generator have the first frequency synchronized with a common reference frequency. The continuous wave signal, the second continuous wave signal, and the calibration signal are generated, respectively, and the second frequency conversion unit performs frequency conversion based on the locally generated signal synchronized with the reference frequency, and the second frequency conversion unit performs frequency conversion. The frequencies of three or more continuous waves of the intermediate frequency signal are each synchronized with the reference frequency.

With this configuration, the phase characteristic calibrator according to claim 8 of the present invention can obtain continuous waves of three or more waves in the intermediate frequency band without frequency error, and between three or more continuous waves in the intermediate frequency band in the calibration unit. The phase difference of can be easily calculated.

The phase characteristic calibration method according to claim 9 of the present invention is a phase characteristic calibration method for calibrating the phase characteristic of the measurement circuit (50), and is a calibration signal obtained by synthesizing three or more continuous waves having different frequencies. _Which frequency is smaller than the generation step of generating Er), the first light in which three or more continuous lights having different frequencies are combined, and the three or more continuous lights of the first light. a step of generating a second light for generating a synthesized local light (P _L) is or large frequency of the continuous light, an intermediate frequency by performing frequency conversion on the calibration signal by means of an electro-optical effect by using the local light _{A frequency conversion step that outputs an intermediate frequency signal (EIF} ) in which three or more continuous waves in the band are combined, and a frequency change that changes the frequency of three or more continuous waves of the calibration signal within a predetermined frequency band. Each time the frequency is changed by the step and the frequency change step, the frequency interval between the first light and the second light is changed according to the value of the changed frequency, and three or more waves of the intermediate frequency signal are changed. The phase difference between continuous waves is calculated to acquire the first phase difference characteristic over the entire predetermined frequency band, and the calibration is performed using the measurement circuit for each frequency change due to the frequency change step. The signal is measured, the phase difference between three or more continuous waves output from the measurement circuit is calculated, and the second phase difference characteristic over the entire predetermined frequency band is acquired, and the acquired said. A calibration step for calibrating the phase characteristics of the measurement circuit based on the first and second phase difference characteristics is provided, and any frequency of three or more continuous waves of the intermediate frequency signal is the calibration signal. It is lower than any frequency of 3 or more continuous waves, and the frequency interval of 3 or more continuous waves of the calibration signal is different from the frequency interval of 3 or more continuous lights of the first light. In addition, the calibration signal and the respective frequencies of the station emission are set so that the frequency interval of three or more continuous waves of the intermediate frequency signal is narrower than the frequency interval of three or more continuous waves of the calibration signal. It is characterized in that it is set.

With this configuration, the phase characteristic calibration method according to claim 9 of the present invention does not use the optical variable delayer having the mechanically movable part as described in the configuration example 1 of FIG. 10, so that the mechanically movable part is not used. The phase characteristics can be calibrated with high frequency resolution without being restricted by. Further, since the short pulse light is not used as in the configuration example 1 of FIG. 10, the short pulse light waveform is not deformed and the conversion characteristics of the electro-optical frequency conversion unit are not changed.

Moreover, the phase characteristic calibration method according to claim 9 of the present invention is set so that the frequency interval of three or more continuous waves of the intermediate frequency signal is narrower than the frequency interval of three or more continuous waves of the calibration signal. Therefore, the band handled by the electric circuit can be narrowed as compared with the conventional case, and the phase of the calibration signal can be measured with high accuracy using a low-speed A / D converter with a small amount of calculation. Therefore, the device price can be reduced.

According to the present invention, it is possible to provide an inexpensive phase characteristic calibration device and a phase characteristic calibration method capable of accurately calibrating the phase characteristics of a millimeter wave band signal measurement circuit.

It is a block diagram of the phase characteristic calibration apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the spectrum of each signal of the phase characteristic calibration apparatus of FIG. It is explanatory drawing which shows the spectrum of each signal of the phase characteristic calibration apparatus of FIG. It is a block diagram of an electro-optic frequency conversion part. It is another block diagram of the electro-optic frequency conversion part. It is a block diagram of the phase characteristic calibration apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the spectrum of each signal of the phase characteristic calibration apparatus of FIG. It is a block diagram of the phase characteristic calibration apparatus which concerns on 3rd Embodiment of this invention. It is explanatory drawing which shows the spectrum of each signal of the phase characteristic calibration apparatus of FIG. It is a block diagram of the phase characteristic calibration system which concerns on the related technology. It is a block diagram of another phase characteristic calibration system which concerns on a related technique. It is explanatory drawing which shows the spectrum of each signal of the phase characteristic calibration system of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a configuration diagram of a phase characteristic calibration device 1 according to a first embodiment of the present invention.
The phase characteristic calibration device 1 calibrates the phase characteristics in a predetermined frequency band of the millimeter wave band signal measurement unit 50, which is a measurement circuit to be calibrated. The phase characteristic calibration device 1 includes a station emission generation unit 10, a calibration signal generation unit 20, an electro-optic frequency conversion unit 30, a calibration processing unit 40, and a frequency changing unit 70.

[Local light emission generator]
First, the local light emission generating unit 10 will be described.
The local emission generator 10 includes a first CW signal generator 11, an optical comb generator 12, an optical brancher 13, a first optical bandpass filter (BPF) 14, and a second optical bandpass filter (BPF). ) 15, a second CW signal generator 16, an optical phase modulator 17, and an optical combiner 18. Local light generator 10 is different from the first light P ₄ to 3 or more waves continuous light frequency is synthesized, less than or greater than any frequency of the first three waves or more consecutive of light from each other the second and the light P ₂ is a continuous light of frequency is adapted to generate a synthesized local light P _L. The local light emission generating unit 10 corresponds to the generating unit of the present invention.

The first CW signal generator 11 is adapted to output a CW signal (electric signal) E _{1 having a frequency f L1.}

Optical comb generator 12 receives the CW signal _{E 1} of the frequency _{f L1,} optical comb _{P 1} having a large number of optical spectrum components of the frequency interval _{f L1} about the optical frequency _{f 0} as shown in FIG. 2 (a) Is to occur. Specifically, the optical comb generator 12 includes a CW light source having _{an optical frequency of f 0} , an optical phase modulator to which a CW signal having _{a frequency f L1} is input, and a fabric having a free spectrum range that is an integral fraction of _{f L1.} and Perot resonator may be a combination of, or may be a central optical mode-locked laser frequency f ₀ which outputs a short pulse light of a repetition frequency f _L1. In the former case, by increasing the finesse of the Fabry-Perot resonator, in the latter case, by narrowing the pulse width of the short pulse light, it is possible to increase a spectral width of the optical comb P _1.

The output side of the optical comb generator 12, by adding an optical pulse compressor, such as a highly nonlinear optical fiber (not shown), it is possible to further widen the spectral width of the optical comb P _1. For example, it is possible to generate the comb _{P 1} number 100GHz~ number THz width by the number 10GHz intervals.

The optical turnout 13 branches the optical comb P1 output from the optical comb generator 12 _{into two, and sends the optical comb P 1} to the first optical bandpass filter 14 and the second optical bandpass filter 15, respectively. ..

上記式（３）において、光周波数が高い方をｆ_２としている（ｆ_２＞ｆ_１）。ｎは整数である。 The first optical bandpass filter 14 and the second optical bandpass filter 15 are adapted to extract predetermined optical spectrum components that are different from each other. Assuming that the optical frequencies of the extracted optical spectrum components are f ₁ and f ₂ , respectively, the frequency interval is expressed by the following equation (3).

In the above formula (3), towards the optical frequency is high is set to _{f 2 (f 2> f 1} ). n is an integer.

As will be described in detail later, when obtaining the phase characteristics of the calibration signal in a predetermined frequency band, the frequency interval f ₂ −f ₁ of the two optical spectrum components is changed according to the frequency of the calibration signal. do. Specifically, changing the frequency f _L1 of the CW signal E ₁ generated by the first CW signal generator 11, or the optical spectral components selected by the first optical band-pass filter 14 or the second optical bandpass filter 15 By changing n by changing, the frequency interval f _2- f ₁ can be changed. The frequency f _L1 of the CW signal E ₁ can be varied continuously, it is difficult to a wide frequency range variable. If you alter the n by changing the optical spectral components selected by the first optical band-pass filter 14 or the second optical bandpass filter 15 can be varied greatly frequency interval f ₂ -f _1, continuously variable Cannot be. Thus, by combining the two, it is possible to change the frequency interval f ₂ -f ₁ over a continuous and wide range.

Here, the optical spectrum components extracted by the first and second optical bandpass filters 14 and 15 are equidistant from the central optical frequency f _{0 of the optical comb P 1 (f 2-} f ₀ = f ₀ −f ₁ ). That is, the two optical spectrum components having substantially the same amplitude may be used. Alternatively, in consideration of the loss of the optical phase modulator 17 described later, an optical spectrum close _{to the central optical frequency f 0} so that the amplitude on the second optical bandpass filter 15 side becomes large as shown in FIG. 2A. May be extracted (f _{2- f 0} <f ₀ −f ₁ ). Further, instead of the optical branching device 13, the first and second optical bandpass filters 14 and 15, an arrayed waveguide grating (AWG) is used so that branching and optical spectrum extraction can be performed by one device. You may. Optical spectrum of the output light _P 2, _{P 3} from the first and second optical band-pass filter 14 and 15 is as shown in FIG. 2 (b).

The second CW signal generator 16 outputs a CW signal (electric signal) E _{2 having a frequency f L2} to the optical phase modulator 17.

The optical phase modulator 17 uses, for example, _{the electro-optical effect of a LiNbO 3} crystal to change the phase of light input to the crystal by applying a voltage to the crystal. By inputting the CW signal E ₂ of the frequency f _L2 to the optical phase modulator 17, _{the optical spectrum component of the optical frequency f 2} is phase-modulated, and as shown in FIG. 2 (c), the optical frequency f ₂ is the center. A sideband wave with a frequency interval f _{L2 is generated.} The optical phase modulator 17 corresponds to the optical modulator of the present invention.

Here, the amplitude of the sideband wave changes depending on the modulation degree of the phase modulation. For example, assuming that the input voltage of the optical phase modulator 17 is _{a sine wave of 0.913 V π} (peak-to-peak), the optical frequency f ₂ −f. _L2, 3 one light spectral component of _{f 2, f} 2 _{+ f L2} is substantially the same amplitude. Here, V _π is a voltage value required to change the phase of light by π in the optical phase modulator 17.

Further, by inputting to the optical phase modulator 17 by superimposing a sine wave of frequency _{2f L2} in addition to the sine wave of the frequency _{f L2,} the optical frequency _{f 2 -2f L2, f 2 -f} L2, f 2, f It is also possible to make the five optical spectrum components of ₂ + f _L2 and f ₂ + 2f _{L2 have substantially the same amplitude.}

Further, instead of the optical phase modulator 17, an optical intensity modulator may be used to similarly generate a sideband wave having a _{frequency interval of f L2.} For example, linear optical modulation is performed by using a region in which the input voltage and the output optical electric field amplitude of the Machzenda type optical intensity modulator are substantially proportional to each other, or by correcting the non-linear characteristic of the relationship between the input voltage and the output optical electric field amplitude. be able to.

For example, a DC component and _{a sinusoidal wave having a frequency f L2} are input to an optical intensity modulator _{to generate three optical spectrum components having an optical frequency f 2-} f _L2 , f ₂ , f ₂ + f _L2 , or a DC component and a DC component. five optical spectrum of the frequency _{f L2} and the optical frequency _f 2 _-2f L2 sine wave having a frequency _{2f L2} are input to the optical intensity _{modulator, f 2 -f L2, f 2} , f 2 + f L2, f 2 + 2f L2 It is possible to generate various optical spectrum components such as generating components. If direction of the optical spectrum broadening due to the light intensity modulator than the frequency spacing of the optical comb P ₁ replace it or optical phase modulator 17 is small, the second optical band pass filter 15 and the optical phase modulator 17 or the light intensity modulation The order of the vessels may be reversed.

Optical multiplexer 18, the output light P ₂ of the first optical band-pass filter 14, and an output light P ₄ optical phase modulator 17 combined polarization multiplexes, so as to output as a local light P _L It has become. Bureau optical spectrum of the light-emitting P _L is as shown in Figure 2 (d). _{The output light P 4} of the optical phase modulator 17 _{corresponds to the first light of the present invention, and the output light P 2} of the first optical bandpass filter 14 corresponds to the second light of the present invention.

An optical attenuator or an optical amplifier that adjusts the optical power may be inserted into the local emission generator 10 as needed. For example, variable light attenuation to at least one of the optical path of the first optical bandpass filter 14 or the optical path of the second optical bandpass filter 15 in order to adjust the intensity ratio of the optical spectrum components of the optical frequency f ₁ and the optical frequency f _2. You may insert a vessel. Further, in order to increase the optical power of the local light P _L, it may be inserted an optical fiber amplifier after the optical coupler 18.

[Calibration signal generator]
Next, the calibration signal generation unit 20 will be described.
As shown in FIG. 1, the calibration signal generator 20 includes an intermediate frequency signal generator 21, a local signal generator 22, and a frequency converter 23. The calibration signal generation unit 20 is adapted to generate _{a calibration signal Er in} which three or more continuous waves having different frequencies within a predetermined frequency band are combined. Specifically, the calibration signal generating unit 20, as shown in FIG. 2 (e), the frequency _{f c -f m, f c,} the electrical signal of a millimeter wave band, including at least three spectral components of f c + _{f m} (Calibration signal _Er ) is output. The calibration signal generation unit 20 corresponds to the generation unit of the present invention.

Intermediate frequency signal generator 21, a D / A converter, which is an intermediate frequency signal E ₃ comprising at least three spectral components of the frequency interval f _m such that the output directly by the D / A converter. Instead of the D / A converter, an oscillator for generating a CW signal at an intermediate frequency, an oscillator for generating a CW signal of a frequency f _m, may generate an intermediate frequency signal E ₃ with a mixer ..

Local oscillation signal generator 22 is adapted to generate a local oscillation signal E ₄ of CW. Local oscillation signal generator 22 for generating a local oscillation signal E ₄ in the millimeter wave band may include a frequency multiplier for converting a frequency an integer multiple.

The frequency converter 23 includes, for example, a mixer, and the intermediate frequency signal E ₃ is frequency-converted (up-converted) by _{using the local signal E 4 generated by the local signal generator 22, for example, a horn.} It is radiated from the antenna 24 as a calibration signal _Er . Instead of the horn antenna 24, a waveguide, a coaxial cable, or a coaxial connector may be used to connect to the electro-optical frequency conversion unit 30 or the millimeter wave band signal measurement unit 50. The calibration signal generation unit 20 of FIG. 1 is configured to perform frequency conversion once, but may be configured to perform frequency conversion a plurality of times.

The intermediate frequency signal generator 21 and the local signal generator 22 use, for example, a reference signal of 10 MHz to be used with the first CW signal generator 11 and the second CW signal generator 16 of the local light emission generator 10. The frequencies are synchronized, but it is not always necessary to synchronize the frequencies.

Generally, in the measurement of phase characteristics, a method of measuring at one time by using a wide band signal covering the frequency band requiring phase characteristic calibration as a calibration signal, or dividing the frequency band requiring phase characteristic calibration into a plurality of parts. , There is a method of obtaining the phase characteristics of the required band by performing a plurality of measurements using each narrow band signal as a calibration signal. In this embodiment, the latter method is used, and a multitone signal having three or more waves (that is, a continuous wave having three or more waves having different frequencies) is used as a calibration signal, and the multitone signal is within a predetermined frequency band. The phase characteristic of the frequency band is obtained by detecting the phase difference between the multitones while changing the frequency of. However, the present invention is not limited to the latter method, and covers the frequency band requiring phase characteristic calibration by increasing the wave number of the continuous wave of the calibration signal and the wave number of the continuous light of the first light. It is also possible to apply it to the method of measuring at one time.

In general, it is not easy to operate a relatively high-speed D / A converter or A / D converter with a fixed time origin, but as will be described in detail later, a multitone signal of three or more waves is used. By obtaining the second-order difference of the phases with the first and second phase difference calculators 41 and 43, the phase characteristics can be obtained even when the time origin is indefinite, that is, the absolute time is unknown.

[Electro-optic frequency converter]
Next, the electro-optical frequency conversion unit 30 will be described.
As shown in FIG. 1, the electro-optical frequency conversion unit 30 includes an electro-optical crystal 31, an optical branching unit 32, and a receiver 33. The electro-optical frequency converter 30, the beat of the local light P _L from the local light generator 10 as a local signal, frequency converted by electro-optical effect calibration signal E _r from the calibration signal generator 20 (down-conversion) _{The intermediate frequency signal EIF} , which is a combination of three or more continuous waves in the intermediate frequency band, is output. The electro-optical frequency conversion unit 30 corresponds to the frequency conversion unit of the present invention.

Electro-optical frequency conversion unit 30 receives the electric field of the calibration signal E _r is applied with a predetermined orientation of the electro-optic crystal 31, a local light P _L to the electro-optical crystal 31 via the optical branching unit 32, an electro-optical The local emission reflected at the tip of the crystal 31 is input to the receiver 33 via the optical branching portion 32.

FIG. 4 is a configuration diagram showing a configuration example of the electro-optical frequency conversion unit 30. The electro-optical frequency conversion unit 30'is a method of detecting a change in the polarization of the reflected light from the electro-optical crystal 31. Specifically, the electro-optical frequency converter 30 includes a polarizing beam splitter (PBS) 32', a 1/2 wave plate (HWP) 35, a 1/4 wave plate (QWP) 36, and an electro-optical crystal 31. , And a receiver 33.

Polarization beam splitter 32 ', a local light P _L of the input linearly polarized waves to transmit, the polarization beam splitter 32' is the direction of being set. In the 1/2 wave plate 35 and the 1/4 wave plate 36, when no electric field is applied to the electro-optical crystal 31, 1/2 of the optical power of the reflected light from the electro-optical crystal 31 is reflected by the polarizing beam splitter 32'. 1/2 wave plate 35 and 1/4 wave plate so that the change in the optical power input to the light receiver 33 and input to the light receiver 33 when an electric field is applied to the electro-optical crystal 31 is maximized. It is desirable to adjust the orientation of the plate 36. Further, in order to increase the reflectance of local emission, it is desirable to attach a dielectric reflective film 34 to the tip of the electro-optical crystal 31. With this configuration, an electric signal is output in which an amplitude component proportional to the electric field applied to the electro-optical crystal 31 is superimposed on an offset corresponding to 1/2 of the optical power of the reflected light from the electro-optical crystal 31.

FIG. 5 shows another configuration example of the electro-optical frequency converter. The electro-optical frequency conversion unit 30A has a method of differentially detecting a change in the polarization of the reflected light from the electro-optical crystal 31. Specifically, the electro-optical frequency conversion unit 30A includes a polarizing beam splitter (PBS) 32a similar to the electro-optical frequency conversion unit 30'with the configuration of FIG. 4, a 1/2 wave plate (HWP) 35a, and 1 /. In addition to the 4-wave plate (QWP) 36, the electro-optical crystal 31, and the receiver 33a, a polarizing beam splitter (PBS') 32b, a 1/2 wave plate (HWP') 35b, and a faraday rotator (FR). 37, a receiver 33b, and a differential amplifier 38 are provided.

Electro-optical frequency conversion unit 30A is a local light P _L of the input linearly polarized waves to transmit, the direction of the polarization beam splitter 32b is set. Further, the direction of the 1/2 wavelength plate 35b is set so as to return the polarization rotation of 45 degrees by the Faraday rotator 37 of the incident light. Then, among the reflected light from the electro-optical crystal 31, the light transmitted through the polarizing beam splitter 32a is rotated by 90 degrees, reflected by the polarizing beam splitter 32b, and input to the receiver 33b.

With this configuration, the outputs of the light receiver 33a and the light receiver 33b have an amplitude component proportional to the electric field applied to the electro-optical crystal 31 at an offset corresponding to 1/2 of the optical power of the reflected light from the electro-optical crystal 31. Since they are superimposed on each other in opposite directions, the offsets of the outputs from the differential amplifier 38 cancel each other out and become zero, and the amplitude component proportional to the electric field is doubled. The signal-to-noise ratio is improved because the differential configuration doubles the amplitude of the signal while not doubling the noise.

Further, as described as the electro-optical frequency conversion unit 230 in FIG. 11, the electro-optical frequency conversion unit 30 uses an optical circulator and an optical bandpass filter as the optical branching unit 32 to form a side band of the reflected light from the electro-optical crystal 31. It may be a method of detecting a wave.

Next, the frequency conversion operation in the electro-optical frequency conversion unit 30 will be described.
3 (a) is an optical spectrum of the optical multiplexer 18 the local light P _L output from is an enlarged view of the horizontal axis in FIG. 2 (d). _{FIG. 3B is a spectrum of the calibration signal Er} output from the calibration signal generation unit 20, and is an enlarged view of the horizontal axis of FIG. 2E. f _2- f ₁ and f _c are set to different frequencies. Here, _{an example of f c} > f _2- f ₁ is shown, but the magnitude relationship may be reversed. Usually it is desirable to set the _f 2 -f ₁ to a value close to _{f c,} so that the following equation (4) holds.

_{Further, the frequency interval f L2} of the continuous light having three or more waves of the first light _{and the frequency interval f m} of the continuous wave having three or more waves of the calibration signal _Er are set to different frequencies, and here, f. _{An example of m} > f _L2 is shown, but the magnitude relationship may be reversed. Normally it is desirable to set the f _L2 to a value close to f _m, so that the following equation (5) holds.

Stations and optical spectrum component of the frequency _{f 1} of the light-emitting _{P L,} by the optical spectrum component of the frequency _{f 2,} the beat frequency f ₂ -f 1 = _{nf L1} occurs, calibration signal E by electro-optical frequency conversion unit 30 The spectral component of the frequency f _{c of r} is frequency-converted to _{the frequency f IF1} = f _{c −} nf _L1.

Similarly, the optical spectrum component of the frequency _{f 1} of the local light _{P L,} by the optical spectrum component of the frequency _{f 2 -f L2, f 2 -f} L2 -f 1 = nf L1 frequency beat of _{-f L2} is generated Then, the spectral component of the frequency f _c − f _{m of the calibration signal Er} is frequency-converted by the electro-optical frequency conversion unit 30 into _{the frequency f IF 1} − f _{m 1 = f c} − f m − (nf _L1- f _L2 ). .. Here, the frequency interval after frequency conversion is f _m1 = f _m −f _L2 .

Similarly, the optical spectrum component of the frequency _{f 1} of the local light _{P L,} by the optical spectrum component of the frequency _f 2 _{+ f L2,} the frequency beat of _{f 2 + f L2 -f 1 =} nf L1 + f L2 is generated, electrical spectral component of the frequency _f c + _{f m} of the calibration signal _{E r} by the optical frequency conversion unit 30, the frequency _{f IF1 + f m1 = f c} + f m - is frequency-converted into _(nf L1 _{+ f L2).} From the relationship between equations (4) and (5), the following equations (6) and (7) hold.

That is, the carrier frequency f _{c of} the high frequency (millimeter wave band) calibration signal _Er is converted to the low frequency intermediate frequency f _IF1 , and at the same time, the wide frequency interval f _{m of the calibration signal Er} is the intermediate frequency signal E. It is converted to a narrow frequency interval _{fm1 in IF.} In other words, any frequency of the intermediate frequency signal E _IF of 3 or more waves continuous wave also is set to be lower than both the frequency of 3 or more waves continuous wave calibration signal E _r, and the intermediate frequency interval between successive wave three or more waves of frequency signal E _IF is set to be narrower than the frequency intervals of 3 or more waves continuous wave calibration signal E _r.

In this manner, converts the calibration signal E _r in the millimeter wave band to the A / D convertible intermediate frequency by a frequency interval f _m1 in the intermediate frequency signal E _IF set sufficiently narrow, the electro-optical frequency conversion unit It is possible to sufficiently reduce the change in the phase difference of the three spectral components of _{f IF1-} f _m1 , f _IF1 , and f _IF1 + f _m1 due to the frequency characteristics of the electric circuit after the receiver 33 of 30.

If the intermediate frequency f _IF1 is too low, the signal-to-noise ratio deteriorates due to 1 / f noise of the electric circuit, and if it is too high, a high-speed receiver, A / D converter, etc. are required, so an appropriate frequency is selected. It is desirable to do.

Besides frequency conversion described above it is also, for example, station frequency of _{f 2 + f L2 -f 1 =} nf L1 + f L2 between the optical spectrum component of the frequency _{f 1} of the light-emitting _{P L} and the optical spectrum component of the frequency _f 2 _{+ f L2} There are various combinations such that the spectral component of the frequency f _c of the calibration signal _Er is frequency-converted to the _{frequency | f c} − (nf _L1 + f _{L2) | by the beat of} The spectrum of the output signal is as shown in FIG. 3 (c). From these spectra, the low-pass filter or a band-pass filter (not shown), or _by using a narrow photodetector of bands, so as to extract the spectral components in the vicinity of _{f IF1} including _f IF1 _{-f m1, f IF1,} f IF1 _{+ f m1} It may be. FIG. 3 (d) is an enlarged view of the vicinity of the _{frequency f IF1 in} FIG. 3 (c). The electro-optical frequency conversion unit 30 outputs an intermediate frequency signal E _{IF including at least three spectral components of f IF1} −f _m1 , f _IF1 , and f _IF1 + f _m1.

[Frequency change section]
The frequency changing unit 70 receives an instruction signal from the calibration processing unit 40 and changes the frequency of three or more continuous waves of _{the calibration signal Er within a predetermined frequency band.} Further, the frequency changing unit 70 has a frequency interval between the first light (continuous light of three or more waves) and the second light according to the frequency value of three or more continuous waves of _{the calibration signal Er to be changed.} Is to be changed.

[Calibration processing unit]
Next, the calibration processing unit 40 will be described.
As shown in FIG. 1, the calibration processing unit 40 includes a first phase difference calculator 41, a second phase difference calculator 43, an adder 42, and a phase correction value calculator 44. The calibration processing unit 40 receives the phase difference characteristic of the calibration signal Er acquired by using the electro-optical frequency conversion unit 30 and the millimeter-wave band signal measurement unit 50 when the calibration signal Er is input to the millimeter-wave band signal measurement unit 50. based on the phase difference characteristics of the signal E ₈ output, calculates a phase correction value for correcting the phase characteristic of the millimeter wave band signal measuring unit 50, the phase correction value phase corrector 55 holds The data is updated. The calibration processing unit 40 corresponds to the calibration unit of the present invention.

The first phase difference calculator 41 changes the frequency interval between the first light and the second light according to the value of the changed frequency for each frequency change by the frequency changing unit 70, and changes the frequency interval between the first light and the second light, and the intermediate frequency signal _EIF. The phase difference between three or more continuous waves is calculated, and the first phase difference characteristic over a predetermined frequency band is acquired.

_{Specifically, when the calibration signal Er} is input to the electro-optic frequency conversion unit 30, the first phase difference calculator 41 _{outputs the intermediate frequency signal E IF} frequency f _{IF 1 from the electro-optic frequency conversion unit 30.} Calculate the phase difference of the spectral components of −f _m1 , f _IF1 , f _IF1 + f _m1. For example, the intermediate frequency signal E _IF is A / D converted at a predetermined sampling frequency, and the obtained digital signal is multiplied by the sine function and cosine function _{of each frequency f IF1} −f _m1 , f _IF1 , f _IF1 + f _m1. It is also possible to integrate for a predetermined number of samples, calculate the phase of each spectral component by an inverse tangent function, and calculate the second-order difference of the phase as described later.

The second phase difference calculator 43 is an intermediate frequency signal measuring device of the millimeter wave band signal measuring unit 50 for each frequency change by the frequency changing unit 70 when _{the calibration signal Er is input to the millimeter wave band signal measuring unit 50.} 53 will calculate the phase difference between the three waves or more continuous wave signal E ₈ output from, so as to obtain a second phase difference characteristics throughout a predetermined frequency band. The processing content of the second phase difference calculator 43 is the same as that of the first phase difference calculator 41, but in the second phase difference calculator 43, A of the intermediate frequency signal measuring device 53 of the millimeter wave band signal measuring unit 50 The digital signal obtained by A / D conversion by the / D converter may be used.

Phase difference output from the first phase difference calculator 41 (second difference value), after the phase difference between the local light P _L via the adder 42 as required (second difference value) is added, It is input to the phase correction value calculator 44. Station optical amplitude modulator in place of the optical phase modulator 17 of the light emitting generation portion 10 is used, if it is an ideal amplitude modulation, the phase difference between a local light P _L to become zero, by the adder 42 addition of the phase difference between the local light P _L is not required.

Phase correction value calculator 44, the characteristics of the phase difference obtained by adding the phase difference between the local light P _L as needed to the phase difference calculated by the first phase difference calculator 41, # 2 The phase correction value of the millimeter wave band signal measuring unit 50 is calculated based on the characteristics of the phase difference calculated by the phase difference calculator 43. The calculated phase correction value is sent from the phase correction value calculator 44 to the phase corrector 55 of the millimeter wave band signal measuring unit 50, and is used for phase correction when the signal to be measured is measured by the millimeter wave band signal measuring unit 50. Be done.

The calibration processing unit 40 and the frequency changing unit 70 use, for example, a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, an external storage device, and the like. However, a part or all of the functions (excluding A / D conversion) can be realized by executing various programs stored in the ROM or the like on the CPU.

[Millimeter wave band signal measurement unit]
Next, the millimeter wave band signal measuring unit 50 to be calibrated will be described.

The millimeter-wave band signal measuring unit 50 is a signal analyzer that frequency-converts (down-converts) a high-frequency signal in the millimeter-wave band and measures the signal characteristics. May have a function of displaying. Specifically, the millimeter-wave band signal measuring unit 50 includes a local signal generator 52, a frequency converter 51, an intermediate frequency signal measuring device 53, and a phase corrector 55. The calibration target is not limited to this configuration, and any circuit that handles high-frequency signals in the millimeter wave band can be the calibration target.

The local signal generator 52 generates a CW local signal. _{The frequency converter 51 performs frequency conversion (down-conversion) of the calibration signal Er} or the signal to be measured received by, for example, the horn antenna 56, using the local signal, and converts it into an intermediate frequency signal. Instead of the horn antenna 56, a waveguide, a coaxial cable, or a coaxial connector may be used to connect to the calibration signal generator 20 or the signal to be measured. The intermediate frequency signal measuring device 53 includes an A / D converter, and converts the intermediate frequency signal into a digital signal. The digital signal output from the intermediate frequency signal measuring device 53 is selectively sent to the second phase difference calculator 43 or the phase corrector 55 by the changeover switch 54. The phase corrector 55 performs phase correction on the digital signal from the intermediate frequency signal measuring device 53 using the information updated by the phase correction value calculator 44, and outputs the measurement result. When analyzing the modulation signal and displaying the error vector amplitude (EVM) or the like, the modulation analysis is performed using the output of the phase corrector 55.

The local signal generator 52 may include a frequency multiplier that converts the frequency to an integral multiple. Further, although the configuration in which the frequency conversion is performed once is shown here, the configuration in which the frequency conversion is performed a plurality of times may be performed, and a filter for removing unnecessary frequency components may be included.

[Calibration method]
Next, a method of calibrating the frequency characteristics of the millimeter wave band signal measuring unit 50 will be described.

The frequency characteristic (complex number including phase) of the calibration signal is _Xc (f), the frequency characteristic (complex number including phase) of the millimeter wave band signal measurement unit 50 is G (f), and the calibration signal is millimeter wave band signal measurement. _{Let Y c} (f) be the frequency characteristic (complex number including phase) of the output signal from the intermediate frequency signal measuring instrument 53 when it is input to the unit 50. X _c (f) measures the phase difference of an intermediate frequency signal including three or more spectral components by inputting a calibration signal to the electro-optical frequency conversion unit 30, and sets the carrier frequency f _{c within a predetermined frequency band.} It can be obtained by changing and repeating. Y _c (f) inputs the calibration signal to the millimeter wave band signal measuring unit 50, and measures the phase difference of the intermediate frequency signal including three or more wave spectrum components output from the millimeter wave band signal measuring unit 50. it can be obtained by the repeated while changing the carrier frequency f _c within a predetermined frequency band. G (f) can be obtained from the following equation (8).

ここで、ｆ_ＬＯはミリ波帯信号測定部５０の局発信号の周波数である。

Here, f _LO is the frequency of the local signal of the millimeter wave band signal measuring unit 50.

Then, the frequency characteristic (complex number including phase) of the signal to be measured is X (f), and the frequency characteristic of the output signal from the intermediate frequency signal measuring device 53 when the signal to be measured is input to the millimeter wave band signal measuring unit 50 ( Assuming that the complex number including the phase) is Y (f), X (f) in which the frequency characteristic of the millimeter wave band signal measuring unit 50 is corrected can be obtained as a measurement result from the following equation (9).

As described above, it is possible to calibrate the amplitude characteristic and the phase characteristic at the same time by obtaining the frequency characteristic of the complex number including the amplitude and the phase.
The method of calibrating the phase characteristics will be described in detail below.

As described above, the first phase difference calculator 41 calculates the phases of the spectral components of _{f IF1-} f _m1 , f _IF1 , and f _IF1 + f _m1. f _IF1 -f ₁ the phase phi of the spectral components of _{m1, 2} a phase spectral component phi of _{f IF1, f IF1 + f} phases phi ₃ spectral components _m1, when the frequency interval _{f m} of the calibration signals Delta] f, following equation (10), (11) and (12), calculates the phase difference Δ ² φ / Δf ^2.

The operation of calculating the phase difference Δ ² φ / Δf ^2, repeatedly changing the frequency _{f c} of the calibration signal to the extent necessary to obtain the phase difference as a function of _{f c Δ} ² _φ a _(f c) / _Δf ² .. By taking the difference of the second order of the phase, the phase characteristic can be obtained regardless of the absolute time (that is, even if the time origin is unknown).

Phase difference obtained above is dependent on the phase difference of the optical spectrum component of the local light P _L, when the phase difference of the light spectrum component of the local light P _L is not zero, it is necessary to correct. Specifically, the phase of the optical spectrum component of _f 2 _{-f L2} of the local light _{P L} and phi _L1, the phase of the optical spectrum component of _{f 2} and phi _L2, the phase of the optical spectrum component of f 2 _{+ f L2} When phi _L3, the following equation (13), (14), calculates the phase difference Δ ² φ _L / Δf ² than, local light _{P L} (15). Then, the following equation (16), adds the phase difference Δ ² φ _L / Δf ² of the phase difference _{^{Δ 2 φ (f c) /}} Δf 2 in the local light _{P L} of the output signal from the electro-optical frequency conversion unit 30 by, local light P phase difference Δ ² φ _{c (f c)} the phase of the optical spectrum components are corrected for _{L /} delta] f ² can be obtained.

For example, in the case where the optical phase modulator 17 of the local emission generator 10 has ideal phase modulation, φ _L1 = π / 2, φ _L2 = 0, φ _L3 = π / 2, so Δ ² φ _L / ^{Δ f 2} = Π / f ² _m . An optical amplitude modulator is used instead of the optical phase modulator 17 of the local emission generator 10, and in the case of ideal amplitude modulation, φ _L1 = 0, φ _L2 = 0, φ _L3 = 0, so Δ ² φ _L / Δf ² = 0. This phase difference, because determined by the modulation characteristic of the optical spectrum component of the optical frequency f _2, independent of the normal f ₂ -f 1 ₌ nf _L1, when repeated by changing the frequency f _c of the calibration signal is of a constant value The phase difference may be corrected.

The first CW signal generator 11 of the local emission generator 10, the second CW signal generator 16, the calibration signal generator 20 (intermediate frequency signal generator 21 and the local signal generator 22), and the first phase difference calculation. When the sampling frequency of the A / D conversion of the device 41 is configured to be synchronized with the common reference frequency, the result of the A / D conversion by the first phase difference calculator 41 does not include the frequency error and is accurate. Since the spectrum components of the frequencies f _IF1- f _m1 , f _IF1 , and f _IF1 + f _m1 can be obtained, the phase difference can be calculated easily and accurately.

_{Next, the calibration signal Er} output from the calibration signal generation unit 20 is input to the millimeter wave band signal measurement unit 50.

Specifically, input to the frequency _{f c -f m ', f c} , f c + f m' of the calibration signal _E millimeter wave band signal measuring unit 50 _r having at least three spectral components, the intermediate frequency signal measuring instrument Of the calibration signals output from 53, the phase measurement result of the spectrum component of _{f c} − f _{m ′ is φ 1} ′, the phase measurement result of the spectrum component of _{f c is φ 2} ′, and f _c + f _m ′. the phase measurement result of spectral component 'and, delta] f' phi ₃ frequency interval _{f m} of the calibration signal _{E r} a 'When the following equation (17), (18) and (19), the phase difference delta ² phi' / Calculate Δf ′ ^2.

The operation of calculating the phase difference ^{Δ 2 φ '/ Δf' 2} , repeatedly changing the extent necessary frequency _{f c} of the calibration signal _{E r,} the phase difference as a function of _{^{f c Δ 2 φ '(f}} c) / Δf ′ ² is acquired.

Phase correction value at the frequency _{f c} theta _{(f c),} the following equation (20), (21), can be determined using (22).

Equation (21), in (22), the sum Σ is the integration of while changing the _{f ci} at Delta] f _c interval from the lowest frequency to the frequency _{f c.}

The phase corrector 55 corrects _{the phase so that the phase difference of the spectral components when the calibration signal Er} is input to the millimeter wave band signal measuring unit 50 becomes equal to the phase difference calculated by the first phase difference calculator 41. To do.

As a method of phase correction in the phase corrector 55, a frequency domain correction method or a time domain correction method can be adopted. Frequency domain correction method, into a signal of a frequency domain digital signal time domain obtained by the intermediate frequency signal measuring instrument 53, a discrete Fourier transform, and rotating the phase correction value θ (f _c) by phase, discrete It is converted into a signal in the time domain by inverse Fourier transform. Time domain compensation method obtains a complex amplitude exp {jθ (f _c)} from the phase correction value theta (f _c), is converted into an impulse response by inverse discrete Fourier transform, finite impulse response coefficient the impulse response The (FIR) filter filters the digital signal from the intermediate frequency signal measuring instrument 53.

A spectral interval f _m when measuring the phase difference of the calibration signal E _r in the electro-optical frequency conversion unit 30, the spectral interval f _m when measuring the phase difference of the calibration signal E _r in the millimeter wave band signal measuring unit 50 ' Should be set equally, but not necessarily limited to. Further, a plurality of f _c when measuring the phase difference between the calibration signal E _r in the electro-optical frequency conversion unit 30, a plurality of f at the time of measuring the phase difference of the calibration signal E _r in the millimeter wave band signal measuring unit 50 _It is desirable that c is set to be equal, but the frequency is not necessarily limited to that, and the frequencies of the phase difference information may be matched by interpolation processing or the like.

After the phase correction can be performed as described above, the signal to be measured is input to the millimeter wave band signal measurement unit 50 instead of the calibration signal, and the phase-corrected measurement result is output. When the signal to be measured is a modulated signal such as QPSK (Quadrature Phase Shift Keying) or QAM (Quadrature Amplitude Modulation), the phase-corrected signal should be modulated and analyzed to accurately measure the error vector amplitude (EVM). Can be done. If necessary, the phase calibration using the calibration signal may be performed again periodically or when the ambient temperature changes significantly.

(Second Embodiment)
Next, the phase characteristic calibration device 1A according to the second embodiment of the present invention will be described.

The phase characteristic calibration device 1A according to the present embodiment is different from the first embodiment in that a second frequency conversion unit 60 is provided between the electro-optical frequency conversion unit 30 and the first phase difference calculator 41. There is. Other configurations are the same as those in the first embodiment, the same configurations are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, the second frequency conversion unit 60 includes an amplifier 61, a CW signal generator 62, a mixer 63, and a low-pass filter (LPF) 64. The second frequency converter 60 is for converting the intermediate frequency signal E _IF a further frequency lower second intermediate frequency signal E _IF2 from the electro-optical frequency conversion unit 30.

Specifically, amplifier 61, together with amplifying the intermediate frequency signal E _IF input from the electro-optical frequency conversion unit 30 outputs to the mixer 63, CW signal generator 62, generates a second station oscillation signal of CW And output to the mixer 63. The mixer 63 performs a second frequency conversion (down-conversion) on the intermediate frequency signal EIF using the second station signal, and outputs the intermediate frequency signal _{EIF to the low-pass filter 64.} The low-pass filter 64 extracts a desired spectral component and outputs a _{second intermediate frequency signal EIF2.} A bandpass filter (not shown) may be inserted in front of the mixer 63 in order to reduce spurious components generated by harmonics or the like during the second frequency conversion.

Figure 7 (a) shows the spectrum of the electric output from the optical frequency conversion unit 30 an intermediate frequency signal E _IF. As described above, there are three or more spectral components at a frequency interval f _{m1 centered on the frequency f IF1.} FIG. 7B shows the spectrum of the second station signal output from the CW signal generator 62. FIG. 7C shows the spectrum of _{the second intermediate frequency signal EIF2} output from the low-pass filter 64. _Assuming that the frequency of the second station emission signal from the CW signal generator 62 is f LO2, the second intermediate frequency is f _IF2 = f _IF1 −f _LO2 , and the frequency interval of the second intermediate frequency signal E _{IF2 is f m1} . ..

As shown in FIG. 7 _(c), the spectral components of frequencies lower than f IF1 _{-f m1,} for example, when the frequency _f IF1 _{-2f m1} is lower than the second local oscillator frequency _{f LO2,} the second intermediate frequency signal _{E IF2} Since the spectrum is folded at a frequency of zero, it is desirable to set _{f LO2} so that the folded spectrum does not overlap the three spectral components of _{f IF2-} f _m1 , f _IF2 , and f _IF2 + f _m1. Here, _{an example in which f LO2} <f _IF1 is set is shown, but conversely, f _LO2 > f _IF1 may be set.

In the second embodiment, the intermediate frequency f _IF1 is set to a frequency at which 1 / f noise of the electric circuit is small, and after sufficient amplification by the amplifier 61 of the second frequency conversion unit 60, the second intermediate frequency f _{IF2 is sufficiently low.} It is converted to. Frequency spacing of the intermediate frequency signal _{E IF} as described above is expressed by _f m1 _{= f} m _{-f L2,} sufficiently narrow frequency _{f m1} by setting the frequency _{f L2} of the second CW signal generator 16 appropriately The interval can be set, and _{the frequencies f IF2-} f _m1 , f _IF2 , and f _IF2 + f _m1 of the three spectral components of _{the second intermediate frequency signal E IF2} can all be sufficiently lowered. .. Therefore, while avoiding 1 / f noise of the electric circuit and maintaining a high S / N ratio, the band and sampling speed of the A / D converter of the first phase difference calculator 41 are lowered to realize an inexpensive device. be able to.

(Third Embodiment)
Next, the phase characteristic calibration device 1B according to the third embodiment of the present invention will be described.

The phase characteristic calibration device 1B according to the present embodiment is different from the second embodiment in that the second frequency conversion unit 60A is configured to perform orthogonal frequency conversion. Other configurations are the same as those of the second embodiment, the same configurations are designated by the same reference numerals, and detailed description thereof will be omitted.

In the second embodiment, the negative frequency component is folded back in the second frequency conversion performed by the second frequency conversion unit 60, and the noise in the negative frequency region is also folded back. Therefore, as compared with the case where the second frequency conversion is not performed. The S / N ratio deteriorates by about 3 dB. By arranging a filter that blocks frequency components below f _{LO2 in} the signal path before the second frequency conversion, noise in the negative frequency region after the second frequency conversion can be removed, but generally a steep filter is used. The non-linearity of the phase is large, which causes an error in the phase measurement. Therefore, in the third embodiment, the second frequency conversion unit 60A is configured to perform orthogonal frequency conversion so that the negative frequency component does not fold back in the second frequency conversion.

As shown in FIG. 8, the second frequency converter 60A includes an amplifier 61, a CW signal generator 62a, two mixers 63a and 63b, a 90-degree phase shifter 65, and two low-pass filters (LPF). ) 64a and 64b are provided.

Specifically, amplifier 61 amplifies the intermediate frequency signal _{E IF} input from the electro-optical frequency conversion unit 30 two mixers 63a, and outputs the 63 b. The CW signal generator 62a generates a CW second station signal and outputs the signal to one of the mixers 63a, and also outputs the signal to the 90-degree phase shifter 65. The 90-degree phase shifter 65 outputs the second station transmission signal with the 90-degree phase shift to the other mixer 63b. Mixers 63a, 63b performs a second frequency conversion to the intermediate frequency signal _{E IF} (down-converted) using the second local oscillation signal 90 ° phase different from each other, respectively low-pass filters 64a, output 64b do. The low-pass filters 64a and 64b extract and output desired spectral components. With this configuration, the input signal to the second frequency conversion unit 60A is orthogonally frequency-converted, and two signals of the in-phase component and the orthogonal component are output to the first phase difference calculator 41 as the _{second intermediate frequency signal EIF2.}

Instead of the CW signal generator 62a and the 90 degree phase shifter 65, two D / A converters that generate sine waves that are 90 degree out of phase may be used. A bandpass filter (not shown) may be inserted in front of the mixers 63a and 63b in order to reduce spurious components generated by harmonics or the like during the second frequency conversion.

9 (a) shows the spectrum of the intermediate frequency signal E _IF output from the electro-optical frequency conversion unit 30. As described above, there are three or more spectral components at a frequency interval f _{m1 centered on the frequency f IF1.} FIG. 9B shows the spectrum of the second station signal output from the CW signal generator 62a. FIG. 9C shows the spectrum of _{the second intermediate frequency signal E IF2} output from the low-pass filters 64a and 64b. _Assuming that the frequency of the second station emission signal from the CW signal generator 62a is f LO2, the second intermediate frequency is f _IF2 = f _IF1 −f _LO2 , and the frequency interval of the second intermediate frequency signal E _{IF2 is f m1} . ..

However, the positive and negative frequency components may not be completely separated due to the balance of the two mixers 63a and 63b and the deviation of the orthogonality, and an image component may be generated. Therefore, | f _IF2- f _m1 |, | f _IF2 |, It is desirable to set _{f LO2} so that | f _IF2 + f _m1 | do not overlap with each other. Further, since the frequency zero is affected by the DC offset, it is desirable to set _{f LO2} so that each frequency component of _{f IF2-} f _m1 , f _IF2 , and f _IF2 + f _{m1 does not become zero.} In the present embodiment, f _LO2 <f _IF1 is set, but conversely, f _LO2 > f _IF1 may be set.

In the third embodiment, the intermediate frequency f _IF1 is set to a frequency at which 1 / f noise of the electric circuit is small, and after sufficient amplification by the amplifier 61 of the second frequency conversion unit 60A, the second intermediate frequency f _{IF2 is sufficiently low.} It is converted to. As described above, the frequency interval f _m1 of the intermediate frequency signal E _IF can be set sufficiently narrow, and _{the frequencies f IF2-} f _m1 and f _{IF2 of the} three spectral components of _{the second intermediate frequency signal E IF 2 can be set.} , F _IF2 + f _m1 can all be made sufficiently low. Therefore, it is possible to realize an inexpensive device by reducing the sampling speed of the A / D converter of the first phase difference calculator 41 while maintaining a high S / N ratio while avoiding 1 / f noise of the electric circuit. can. Then, since the positive and negative frequency components can be separated by the orthogonal frequency-converted in-phase component and the orthogonal component, basically, the negative frequency component does not fold back, and the S / N that can occur in the second embodiment does not occur. It has the characteristic that the deterioration of the ratio does not occur.

In the second embodiment and the third embodiment, in order to synchronize with the reference frequency, the first CW signal generator 11 and the second CW signal generator 16 of the station emission generator 10 are calibrated. In addition to the sampling frequency of the A / D conversion of the signal generator 20 and the first phase difference calculator 41, the CW signal generators 62 and 62a that generate the second station output signal of the second frequency converter 60 and 60A are also included. It is good to synchronize with a common reference frequency.

As described above, the present invention has the effect of being able to calibrate the phase characteristics of the millimeter-wave band signal measurement circuit with high accuracy, and is useful for all phase characteristic calibration devices and phase characteristic calibration methods.

1,1A, 1B Phase characteristic calibration device 10-station light emission generator (generator)
11 1st CW signal generator 12 Optical comb generator 13 Optical branching device 14 1st optical bandpass filter 15 2nd optical bandpass filter 16 2nd CW signal generator 17 Optical phase modulator 18 Optical combiner 20 Calibration Signal generator (generator)
21 Intermediate frequency signal generator 22 Local signal generator 23, 51 Frequency converter 30, 30A Electro-optic frequency converter (frequency converter)
31 Electro-Optical Crystal 32 Optical Branch 32', 32a, 32b Polarized Beam Splitter (PBS)
33, 33a, 33b Receiver 34 Dielectric Reflective Film 35, 35a, 35b 1/2 Wave Plate (HWP)
36 1/4 wave plate (QWP)
37 Faraday Rotator (FR)
38 Differential amplifier 40 Calibration processing unit (calibration unit)
41 First phase difference calculator 42 Adder 43 Second phase difference calculator 44 Phase correction value calculator 50 mm wave band signal measurement unit (measurement circuit)
52 Local signal generator 53 Intermediate frequency signal measuring device 54 Changeover switch 55 Phase corrector 60, 60A Second frequency converter 61 Amplifier 62, 62a CW signal generator 63, 63a, 63b Mixer 64, 64a, 64b Low-pass filter Filter (LPF)
65 90 degree phase shifter REF reference signal

Claims (9)

A phase characteristic calibration device (1) that calibrates the phase characteristics of the measurement circuit (50).
A generator (20) that generates _{a calibration signal (Er} ) in which three or more continuous waves with different frequencies are combined, and
The first light in which three or more continuous lights having different frequencies are combined, and the second continuous light having a frequency smaller or larger than any of the three or more continuous lights of the first light. emission station and light is synthesized (P _L) generator for generating a (10),
A frequency conversion unit (30) that outputs an _{intermediate frequency signal (EIF} ) obtained by frequency-converting the calibration signal by an electro-optical effect using the station emission and synthesizing three or more continuous waves in the intermediate frequency band.
A frequency changing unit (70) that changes the frequency of three or more continuous waves of the calibration signal within a predetermined frequency band, and
Each time the frequency is changed by the frequency changing unit, the frequency interval between the first light and the second light is changed according to the value of the changed frequency, and the continuous wave of three or more waves of the intermediate frequency signal is changed. The phase difference between the frequencies is calculated to acquire the first phase difference characteristic over the entire predetermined frequency band, and the calibration signal is measured using the measurement circuit for each frequency change by the frequency changing unit. Then, the phase difference between three or more continuous waves output from the measurement circuit is calculated, the second phase difference characteristic over the entire predetermined frequency band is acquired, and the acquired first and the first and the acquired are obtained. A calibration unit (40) that calibrates the phase characteristics of the measurement circuit based on the second phase difference characteristic, and
The frequency of any of the three or more continuous waves of the intermediate frequency signal is lower than any of the frequencies of the three or more continuous waves of the calibration signal, and the three or more continuous waves of the calibration signal. The frequency interval of the first light is different from the frequency interval of the continuous light of three or more waves of the first light, and the frequency interval of the continuous wave of three or more waves of the intermediate frequency signal is three or more waves of the calibration signal. A phase characteristic calibrator apparatus characterized in that the calibrated signal and the respective frequencies of the station emission are set so as to be narrower than the frequency interval of a continuous wave. The generator (10) is an optical comb having a first CW signal generator (11) that generates a first continuous wave signal and a plurality of optical spectrum components at intervals of frequencies of the first continuous wave signal. The optical comb generator (12) that generates the light, the optical brancher (13) that splits the output light from the optical comb generator into two, and the light that is different from the output light of one and the other of the optical brancher. A first optical bandpass filter (14) and a second optical bandpass filter (15) for extracting spectral components, and a second CW signal generator (16) for generating a second continuous wave signal. Light that applies amplitude modulation or phase modulation to the output light of the second optical bandpass filter with the second continuous wave signal to generate a plurality of sideband waves at intervals of the frequencies of the second continuous wave signal. The first aspect of claim 1 is characterized by having a modulator (17) and an optical combiner (18) that combines the output light of the first optical bandpass filter and the output light of the optical modulator. The phase characteristic calibrator described. The first CW signal generator, the second CW signal generator, and the generator are the first continuous wave signal, the second continuous wave signal, and the second continuous wave signal having a frequency synchronized with a common reference frequency. The phase characteristic calibrator according to claim 2, wherein each of the calibration signals is generated, and the frequencies of three or more continuous waves of the intermediate frequency signal are synchronized with the reference frequency. A second continuous wave of three or more waves in the second intermediate frequency band is synthesized by amplifying three or more continuous waves of the intermediate frequency signal and performing frequency conversion between the frequency conversion unit and the calibration unit. It further has a second frequency conversion unit (60) that outputs an intermediate frequency signal ( _EIF2 ), and the calibration unit uses the second intermediate unit that outputs an intermediate frequency signal instead of the intermediate frequency signal. The phase difference between three or more continuous waves of the frequency signal is calculated, and any frequency of the three or more continuous waves of the second intermediate frequency signal is any of the three or more continuous waves of the intermediate frequency signal. The phase characteristic calibrator according to claim 1, wherein the frequency is set to be lower than the frequency of. The phase characteristic calibration device according to claim 4, wherein the second frequency conversion unit is an orthogonal frequency converter (60A) that outputs an in-phase component and an orthogonal component of the second intermediate frequency signal. A second continuous wave of three or more waves in the second intermediate frequency band is synthesized by amplifying three or more continuous waves of the intermediate frequency signal and performing frequency conversion between the frequency conversion unit and the calibration unit. It further has a second frequency conversion unit (60) that outputs an intermediate frequency signal ( _EIF2 ), and the calibration unit uses the second intermediate unit that outputs an intermediate frequency signal instead of the intermediate frequency signal. The phase difference between three or more continuous waves of the frequency signal is calculated, and any frequency of the three or more continuous waves of the second intermediate frequency signal is any of the three or more continuous waves of the intermediate frequency signal. The phase characteristic calibration apparatus according to any one of claims 2 and 3, wherein the frequency is set to be lower than the frequency of the above. The phase characteristic calibration device according to claim 6, wherein the second frequency conversion unit is an orthogonal frequency converter (60A) that outputs an in-phase component and an orthogonal component of the second intermediate frequency signal. The first CW signal generator, the second CW signal generator, and the generator have the first continuous wave signal, the second continuous wave signal, and the frequency synchronized with a common reference frequency. Each of the calibration signals is generated, and the second frequency conversion unit performs frequency conversion based on the locally generated signal synchronized with the reference frequency, and the frequency of a continuous wave of three or more waves of the second intermediate frequency signal is set. The phase characteristic calibration device according to any one of claims 6 and 7, wherein each is synchronized with the reference frequency. This is a phase characteristic calibration method for calibrating the phase characteristic of the measurement circuit (50).
A generation step to generate _{a calibration signal (Er} ) in which three or more continuous waves with different frequencies are combined, and
The first light in which three or more continuous lights having different frequencies are combined, and the second continuous light having a frequency smaller or larger than any of the three or more continuous lights of the first light. and generating steps and light for generating a light emission station synthesized (P _L) of,
A frequency conversion step of frequency-converting the calibration signal by the electro-optical effect using the station emission and outputting an intermediate frequency signal ( _EIF ) obtained by synthesizing three or more continuous waves in the intermediate frequency band.
A frequency change step of changing the frequency of three or more continuous waves of the calibration signal within a predetermined frequency band, and
Each time the frequency is changed by the frequency change step, the frequency interval between the first light and the second light is changed according to the value of the changed frequency, and the continuous wave of three or more waves of the intermediate frequency signal is changed. The phase difference between the frequencies is calculated to acquire the first phase difference characteristic over the entire predetermined frequency band, and the calibration signal is measured using the measurement circuit for each frequency change due to the frequency change step. Then, the phase difference between three or more continuous waves output from the measurement circuit is calculated, the second phase difference characteristic over the entire predetermined frequency band is acquired, and the acquired first and the first and the acquired are obtained. A calibration step of calibrating the phase characteristic of the measurement circuit based on the second phase difference characteristic, and
The frequency of any of the three or more continuous waves of the intermediate frequency signal is lower than any of the frequencies of the three or more continuous waves of the calibration signal, and the three or more continuous waves of the calibration signal. The frequency interval of the first light is different from the frequency interval of the continuous light of three or more waves of the first light, and the frequency interval of the continuous wave of three or more waves of the intermediate frequency signal is three or more waves of the calibration signal. A phase characteristic calibration method, characterized in that the calibration signal and the respective frequencies of the station emission are set so as to be narrower than the frequency interval of a continuous wave.

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