JP2018054417A - Phase fluctuation measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate phase fluctuation of a signal with a single spectrum from a highly stable signal generator, without using a reference signal source.SOLUTION: A phase fluctuation measuring device, which measures phase fluctuation by comparing a signal from a signal source of a device under measurement and a signal obtained by intentionally delaying the signal from the signal source, comprises: a signal source for generating an electric signal with a single frequency; delay means for delaying the signal from the signal source; phase detection means for comparing the phases between the signal from the delay means and the signal from the signal source; data processing means for connecting output from the phase detection means at intervals of delay time of the delay means to output an accumulation of output from the phase detection means; and circuit switching means for using at least the signal source and the phase detection means to measure delay time by the delay means. In addition, phase fluctuation is measured by dividing a signal from the signal source into two signals, intentionally delaying only one of them, and comparing the delayed signal and the non-delayed signal.SELECTED DRAWING: Figure 1

Description

  The present invention is a measuring device that evaluates the phase fluctuation of a single spectrum signal from a highly stable signal generator, and compares the signal generated in the past of the device under test itself with the current signal. The present invention relates to a phase fluctuation measuring apparatus capable of performing the measurement without using a reference signal source.

  To measure the phase fluctuation of the signal (signal under measurement) output from the oscillator, use a reference signal source with a sufficiently low phase fluctuation and a high generation frequency for the signal under measurement. There is a method for evaluating the phase variation of the signal under measurement by comparing the phase with the signal. The DMTD (Dual Mixer Time Difference) method is one of them, and the measurement accuracy depends on the accuracy of the reference signal. In addition, there are measurement techniques such as the spectrum analyzer method, oscilloscope method, and PLL method (Phase Lock Loop).

  The DMTD method is a technique in which a phase reference signal is used to measure a phase difference from the phase reference signal using a phase comparator, and the signal accuracy of an oscillator serving as a reference for phase comparison is the limit of measurement accuracy.

  There is also an analysis method using a cross-correlation method. This cross-correlation method is one of the PLL methods, and uses two systems of sampling circuits for measuring phase fluctuations. Sampling clocks are input from two different oscillators as two types of signals. A signal under measurement is branched and input there, and after sampling in each system, only a phase fluctuation component of the signal under measurement having a correlation is extracted using a correlator.

  One of the merits of this analysis method is that phase fluctuations generated in the sampling circuit are not output from the correlator because there is no correlation. By calculating the correlation of the sampled data and accumulating the results, the measurement time becomes longer, but there is an advantage that the phase fluctuation of the measuring device can be reduced according to the number of integrations. For example, the phase fluctuation of the measurement system can be reduced by 10 dB, integration by 100 times, 15 dB by 1000 times, and 20 dB by 10,000 times. However, the measurement time is 100 times, 1000 times, and 10,000 times longer than when the cross-correlation method is not applied.

Techniques for providing a highly stable and highly accurate oscillator that can be used as a reference signal for phase comparison include the following.
For example, Patent Document 1 (International Publication No. 2008/099735) discloses a technique using an oscillator that can output different frequencies with common phase noise. In this disclosure, for example, an oscillator that outputs both 10 MHz and 5 MHz reference signals that can output a common phase noise is used. With this configuration, when 10 MHz is divided to generate 5 MHz and the phase difference from the originally output 5 MHz is obtained, a phase change of ½ of the phase noise of the oscillator itself can be obtained. Therefore, after the generated 5 MHz is doubled and subtracted from the phase of the 10 MHz or 5 MHz signal, a reference signal in which phase noise is suppressed can be obtained. In this way, if the phase difference from the signal under measurement is measured using the signal with the phase noise corrected as a reference signal, the phase noise of the signal under measurement can be directly obtained.

International Publication No. 2008/099735

  The present invention measures the phase difference at a predetermined time interval with respect to the accumulated phase of the signal under measurement for a predetermined period, and obtains the time sum that is the accumulation of the measured phase difference, thereby reducing the phase fluctuation of the signal under measurement. A measuring device for detection is provided.

A phase fluctuation measuring apparatus according to the present invention includes a signal source that generates an electric signal having a single frequency,
Delay means for delaying a signal from the signal source;
Phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source;
Data processing means for connecting the output from the phase detection means at a delay time interval of the delay means, and outputting the accumulated output from the phase detection means,
Circuit switching means for measuring a delay time by the delay means using at least the signal source and the phase detection means;
The phase variation of the electric signal is measured.

In the present invention, the circuit switching means constitutes a circuit bypassing the delay means, and the first switch means for switching the input of the phase detection means between the delay means and the signal source, Second switch means for interrupting the signal from the signal source to the delay means,
(1) The first switch means connects the input of the phase detection means and the signal source, closes the second switch means and connects the signal source and the delay means to measure the reference phase,
(2) The second switch means is intermittently determined to determine the delay time or delay phase of the delay means.

The configuration for inputting the signal from the signal source to the delay means is as follows:
A signal generating means for generating a signal independently or generating a signal synchronized with the signal from the signal source;
Branching means for branching the signal from the signal generating means into at least a first branch signal and a second branch signal;
And the first branch signal is input to the delay means,
The phase detection means includes
A signal from the delay means to which the first branch signal is input is input to the first phase detection means, a second branch signal is input to the second phase detection means, and the output of the first phase detection means and the second phase detection means This is also a phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source by comparing the phases of the outputs.

Further, the configuration for inputting the signal from the signal source to the phase detection means is as follows:
Signal generating means for generating a signal synchronized with the signal from the signal source;
Branching means for branching the signal from the signal generating means into at least a first branch signal and a second branch signal;
Signal combining means for combining the signal obtained by passing the first branch signal through the delay means and the second branch signal;
First frequency converting means for converting the frequency of the signal from the signal generating means with a first frequency signal before inputting the signal to the branching means;
Second frequency conversion means for converting the frequency with a second frequency signal synchronized with the signal from the signal source before inputting the first branch signal to the signal synthesis means;
A third frequency converting means for performing frequency conversion on the output of the signal synthesizing means with a third frequency signal in a manner opposite to that of the frequency conversion of the first frequency converting means;
With
The output of the third frequency conversion means is input to the phase detection means,
The phase detection means includes
The phase from the third frequency converting means is quantized and converted into a digital signal, and the phase detection of the first branch signal and the phase of the second branch signal are simultaneously performed and detected by digital signal processing. Is also phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source.

  The signal input to the delay means is once converted into a frequency band that can be used by the delay means, and after passing through the delay means, the frequency conversion and the inverse frequency conversion are performed to return to the original frequency. It is also a feature.

Also, before inputting to the branching means, perform the frequency conversion,
The first branch signal is subjected to the inverse frequency conversion after passing through the branch means, and the second branch signal is subjected to the inverse frequency conversion after passing through the delay means.

  The signal generation means generates a multicarrier signal synchronized with the signal from the signal source.

  In the present invention, since the reference signal for direct comparison is not used, the influence due to the phase fluctuation of the reference signal can be excluded, and the frequency stability of the oscillator serving as a reference for direct comparison becomes the limit of measurement accuracy. Conventional problems can be solved.

FIG. 2 is a block diagram showing a configuration example of a phase variation measuring apparatus according to the present invention, which measures a phase variation by comparing a signal obtained by intentionally delaying a signal from a signal source as a specimen with a signal from the signal source. Is to do. It is a block diagram which shows the structural example different from the above of the phase fluctuation measuring apparatus of this invention, branches the signal from the signal source which is a sample into two, delays only one of them intentionally, and a signal with a delay and a delay The phase fluctuation is measured by comparing the signal with no signal. FIG. 2 is a block diagram illustrating a more detailed configuration example of the block diagram of FIG. 1. FIG. 3 is a block diagram illustrating a more detailed configuration example of the block diagram of FIG. 2. In the block diagram of FIG. 2, the frequency conversion is performed before the signal is passed through the delay means, and the frequency conversion is performed after the frequency is changed in reverse, so that, for example, a delay device that can be used only in a specific band is used. It is a block diagram which shows the example of a structure assumed. In the block diagram of FIG. 2, the phase fluctuation is measured by sharing one phase detection means instead of using independent phase detection means for each signal resulting from splitting the signal from the signal generator into two branches. It is a block diagram which shows the structural example for this. (A) is a block diagram showing a frequency conversion example of the present invention in the case of a delay means using sound wave propagation in gas, and (b) is a delay due to propagation of ultrasonic waves in the air as the delay means. It is a figure which shows the outline of the delay unit using. It is a block which shows the apparatus structure for confirming the operation principle of this invention. FIG. 9A is a diagram showing measurement results for the configuration of FIG. 8, (a) is a measurement difference between (A) ΔΘ ₁ (t) and ΔΘ ₂ (t) and (B) measurement of Θ _DMTD (t). (B) shows the difference between (b) the measured value of (b) and Θ _DMTD (t) of (b), and (b) shows the moving average expanded in the vertical axis direction of the difference. (C) is a figure which shows the result of having taken the moving average of (b), and the result of the differential phase meter (DPM) which measured the phase difference of the signal sources A and B directly.

  The present invention will be described in detail below with reference to block diagrams. In addition, about the code | symbol in a block diagram, the same code | symbol shall be used for the block with the same function unless there is special circumstances.

  FIG. 1 shows a configuration example to which the phase variation measuring apparatus of the present invention is applied. This configuration example includes a signal source 1, a delay unit 2, a phase detection unit 3, a data processing unit 4, and a circuit switching unit 5, and is for measuring the phase fluctuation of the electric signal generated by the signal source 1. . However, descriptions of a power supply unit, a display unit for measurement data, a communication unit for performing transmission, and the like are omitted. Here, the signal source 1 is a signal source that generates an electric signal having a single-frequency continuous spectrum, the delay unit 2 is a delay unit that delays a signal from the signal source, and the phase detection unit 3 is Phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source, and the data processing means 4 connects the output from the phase detection means at the delay time interval of the delay means. The circuit processing unit 5 is a circuit switching unit for measuring the delay time by the delay unit.

In order to measure the phase fluctuation using the phase detection means, for example, the following procedure is used. The term “phase fluctuation” as used herein refers to phase fluctuation including phase drift and random changes.
(1) By switching the circuit of the delay means and the signal form generated by the signal source by the circuit switching means 5, a mode in which the delay time which is the delay characteristic of the delay means can be measured is set.
(2) The delay characteristic of the delay means is measured.
(3) The circuit switching means 5 switches the circuit of the delay means or the signal form generated by the signal source, and in the case of the presence or absence of a delay corresponding to the delay time, the phase comparison is performed to determine the delay time. Measure phase variation.
(4) The phase fluctuation value from the time point is obtained by accumulating the phase fluctuation every time the delay time elapses with reference to a specific time point.

Further, in the configuration shown in FIG. 1, the phase detection means 3 has the most complicated configuration. As shown in FIG. 2, the function of this portion is delayed by the delay means via the branch means 7, for example. The function of the first phase detecting means 3a for comparing the signal and the signal from the signal source 1 to detect the phase difference, and the signal from the signal source 1 that has passed through the branching means 7 but is not subject to the delay by the delay means. It may be realized by combining the function of the second phase detecting means 3b for comparing the signals and detecting the phase difference and comparing them by the phase comparing means 8.
The control unit 9 in FIG. 2 is for performing control for measuring the delay time and control for data processing.

  FIG. 3 is based on the block diagram of FIG. 1 and shows an example having a configuration composed of more detailed blocks. The procedure for measuring the phase fluctuation with the configuration of FIG. 3 is shown below. The object to be measured is a highly stable oscillator.

(A) In the signal source 1, the output signal (non-measurement signal) of the oscillator 1-1 is input to the synchronizing circuit of the signal generator (SG) 1-2. SG1-2 generates and outputs a reference signal of 10 MHz (defined as the frequency of the reference signal of this measurement system), for example. This reference signal is delayed by the delay means 2 and then input to the A / D (analog / digital) converter 3-1 of the phase detection means 3 and quantized. The sampling signal (quantization clock) in this quantization is a signal synchronized with the reference signal, and is twice or more the reference signal. The reference signal converted into a digital signal by this quantization is orthogonally demodulated according to an orthogonal demodulation algorithm, and amplitude information and phase information are output. For this phase information, the phase variation is continuously measured along the time axis.
(B) In measuring the phase fluctuation, it is desirable to obtain in advance a reference phase excluding the delay means 2. For this purpose, the A / D converter 3-1 is directly input from the output of the signal generator 1-2 by switching the SW 5-1 of the circuit switching means 5. In this way, the phase detection means 3 reads the phase of the signal from the signal generator 1-2 and sets it as the reference phase.
(C) Next, the SW 5-1 is switched to connect the A / D converter 3-1 to the delay means 2. The delay time of the delay means 2 is measured by adding the frequency count value by the delay time measurement / controller 17 and the frequency component due to the phase difference from the reference phase.
(D) Specifically, first, SW5-2 is opened (released). Next, after the output from the A / D converter 3-1 is monitored and the wave from the signal generator 1-2 becomes zero, the SW5-2 is short-circuited to start the measurement ( At the same time, the delay time measuring / controlling unit 17 starts counting.
(E) This counting is stopped by detecting the rising of the signal from the signal generator 1-2 to a predetermined value at the output from the A / D converter 3-1.
(F) The rising phase angle of the signal from the signal generator 1-2 at the time when the clock count is stopped is obtained. A delay time is obtained by adding the amount obtained by converting the phase difference from the reference phase to the count to the count and multiplying the result by the sampling interval time.
(G) The phase detector obtains the phase difference from the output of the A / D converter 3-1. This phase difference angle is a phase angle corresponding to a clock jitter change difference, and is a phase difference when the delay time is separated. This phase difference is output every time the quadrature demodulation is performed, but can be limited to be output at each delay time interval, for example.
(H) When the phase difference is output for each delay time interval, the data processing means 4 obtains one phase difference data series. With respect to this phase difference data series, a phase fluctuation output is obtained by sequentially accumulating the values of the phase difference data.
In addition, when the phase difference is output each time the quadrature demodulation is performed, a plurality of the outputs are included in one delay time interval, and the same phase difference data series as described above corresponds to each data of the output. Can be made. With respect to each phase difference data series, each phase fluctuation output can be obtained by sequentially accumulating the values of the phase difference data. It is clear that the measurement noise can be suppressed by performing statistical processing such as averaging on the plurality of phase fluctuation outputs obtained in this way by the data processing means 4.

  4 to 6 substantially splits the signal from the signal source 1 into two, only one of them is intentionally delayed, and the delayed signal is compared with the undelayed signal. Thus, the phase fluctuation is measured using a reference signal of an arbitrary modulation system including a continuous wave.

  First, the configuration of FIG. 4 will be described. In the signal source 1, the output signal (non-measurement signal) of the oscillator 1-1 is input to the synchronization circuit of the signal generator 1-2. The signal generator 1-2 generates and outputs a reference signal of 10 MHz (defined as the frequency of the reference signal of this measurement system), for example. The role of the signal generator 1-2 in this example is to generate the reference signal as described above that is synchronized with a signal of almost arbitrary frequency from the oscillator 1-1.

(A) The generated reference signal is input to the signal generator 10 to generate a signal synchronized with the reference signal. The signal generated here may be a signal of any modulation system including a continuous wave. In general, by using a multi-carrier signal, it is possible to improve the signal-to-noise ratio of the measured value by proceeding with averaging in the measurement.
(B) The signal generated and output by the signal generator 10 is branched into two by the branching means 7 via the circuit switching means 5. One of the branched signals is quantized by the A / D converter 3a1 synchronized with the reference signal, passed through the symbol synchronizer 3a2 to find the delimiter of the quantized signal, and orthogonal demodulated by the demodulator 3a3 Then, synchronous demodulation is performed. The other branched signal is subjected to a signal delay by the delay means 2 and then quantized by the A / D converter 3b1 synchronized with the reference signal, and a symbol is used to find a delimiter of the quantized signal. Through the synchronization unit 3b2, the demodulation unit 3b3 performs quadrature demodulation and performs synchronous demodulation.
(C) In measuring the phase fluctuation, it is desirable to accurately measure the delay time of the delay means. For this purpose, first, the SW of the circuit switching means 5 is opened (opened). Thereby, when the signal output values of the A / D converters 3a1 and 3b1 become zero, the SW of the circuit switching means 5 is short-circuited. Then, the time difference when the data from the A / D converters 3a1 and 3b1 rises from zero to a predetermined signal level is measured to obtain a delay time.
(D) Next, in order to measure the phase fluctuation, the SW of the circuit switching means 5 is short-circuited, and the signal from the signal generator 10 is branched by the branching means 7, so that Process.
(E) As a result, the signals demodulated synchronously include the phases of the respective branch signals observed at the same time, so that the phase comparison means 8 can obtain the phase difference between the branch signals from the difference between these phases.
(F) Similarly to the above case, when the phase difference is output at every delay time interval, one phase difference data series is obtained. With respect to this phase difference data series, the data processing means 6 sequentially accumulates the values of the phase difference data becomes the phase fluctuation output.

  When the phase difference is output each time the quadrature demodulation is performed, a plurality of the outputs are included in one delay time interval, and the same phase difference data series as described above is associated with each data of the output. Can do. With respect to each phase difference data series, each phase fluctuation output can be obtained by sequentially accumulating the values of the phase difference data. It is clear that measurement noise can be suppressed by performing statistical processing such as averaging for a plurality of phase fluctuation outputs obtained in this way.

  As shown in FIG. 4, the A / D converter 3a1, symbol synchronizer 3a2, demodulator 3a3, A / D converter 3b1, symbol synchronizer 3b2, demodulator 3b3, phase comparator 8, data processing The means 6 and the control unit 9 are configured in a computer system. Here, the control unit 9 controls the SW of the circuit switching means 5 in addition to the control in the computer.

FIG. 5 assumes a case where it is desired to use a delay device that can be used only in a specific band that cannot be handled by the signal generating means 10. The carrier frequency of the signal from the signal generating means 10 is converted into an arbitrary frequency and measured. The configuration is shown.
In the configuration of FIG. 5, frequency conversion (for example, up-conversion) is performed by the frequency conversion unit 11 immediately before the branching unit 7, and frequency conversion (for example, down-conversion) is performed by the frequency conversion unit 12 after branching by the branching unit 7. In the branch having the delay means, the process is executed after the delay means. In the branch having no delay means, the process is executed after the branch. These up-conversion and down-conversion do not need to cancel each other in frequency.

  This frequency conversion can also be performed in order to match the frequency band of the signal passed through to the usable frequency band of the delay means 2. When this frequency band is in a low frequency band, down conversion is performed by the frequency conversion unit 11 and up conversion is performed by the frequency conversion unit 12 so that the frequency band can be adapted to the band of the delay unit in the relatively low frequency band. it can. Also in this case, as in the case described above, these up-conversion and down-conversion do not have to cancel each other.

  FIG. 6 does not use the phase detection means 3 independent of each other as in the configuration of FIG. 5 after branching the signal from the signal generation means 10, but uses one phase detection means to share the phase fluctuation. Measure.

  For this purpose, as shown in FIG. 6, the frequency conversion means 11 performs frequency upconversion before branching, and the frequency conversion means 12 performs frequency downconversion after combining by the signal synthesis means 14, or vice versa. It is set as the structure which performs. One of the signals branched by the branching means 7 is delayed by the delay means 2. Furthermore, in order to make the frequency of the signals in these two branches slightly different from each other, the frequency conversion means 13 performs frequency conversion for slightly increasing or decreasing the frequency of one signal in the branch. This frequency conversion may be performed on either side of the branch. These two branched signals are synthesized by the signal synthesis means 14.

  The synthesized two branch signals are frequency-converted by the frequency converting means 12 as described above. This frequency conversion does not necessarily cancel the effect of the frequency conversion means 11. The phase of the frequency-converted signal is detected by the phase detection means 3a. Here, the two branch signals are simultaneously quantized, and phase difference detection is performed in addition to symbol synchronization and demodulation. The sampling frequency in this quantization is desirably a frequency that is at least twice the maximum frequency of the branch signal.

  Generally, in order to detect a slow phase fluctuation component exhibited by an oscillator, a delay element having a delay time characteristic as large as possible is desired. As a conventional delay element, a mercury delay element that has been used as a computer storage device for a period of time and a delay element that uses the propagation of a surface wave of an individual or a sound wave in a bulk are already well known. An element can be used.

  4, 5 and 6, the signal from the signal generation means 10 is only used as a parameter and is eventually erased. Therefore, various modulation waves can be used. For example, in addition to continuous wave (CW), amplitude modulation (AM), frequency modulation (FM), phase shift keying modulation (PSK), quadrature amplitude modulation (QAM), orthogonal frequency division multiplex modulation (OFDM), etc. .

  Further, in order to realize a delay time larger than those of these delay elements, sound wave propagation in gas can be used. FIG. 7B shows an example of a delay unit when air is used, and FIG. 7A shows an example of a phase variation measuring apparatus using this delay unit for the delay means 2. For example, the speed of sound at 1 atm 0 ° C. is known to be 331 m / sec for dry air and 258 m / sec for carbon dioxide. become.

  The delay means shown in FIG. 7 (b) is placed in a container for separating from external noise, and a delay unit whose delay time is a sound wave propagation time until an ultrasonic wave is emitted from a sound generator and received by a sound receiver. It is. In addition, it is possible to suppress the influence due to the temperature dependency of the sound wave propagation speed by using a thermostatic bath or by frequently measuring the delay time, but in the delay unit, the temperature, atmospheric pressure, By providing a sensor such as humidity and correcting the delay time by the data processing means based on data obtained therefrom, it is possible to suppress frequent measurement of the delay time as described above.

  In the configuration shown in FIG. 7A, since the propagation of ultrasonic waves in the gas is used, the signal generating means 10 generates a signal of, for example, 40 kHz in synchronization with a signal of, for example, 10 MHz from the signal source 1. This is a substantial frequency down-conversion for adapting to the transmission band characteristic of the delay means 7. In this example, two branches are made after frequency conversion, one is not delayed and the other is delayed by a delay element. The subsequent processing is the same as the processing after each A / D conversion in FIG.

The present invention is characterized by the function of measuring its own phase fluctuation with a signal generator (oscillator) alone, but in the experiment, it is verified using a phase difference meter that compares with a reference phase. Therefore, two basic circuits of the present invention are used in parallel. First, the phase difference between the signals from the two oscillators is measured with the phase difference system DPM, one from each system, and the phase of the oscillator is measured independently through the delay unit and AD converter in each system. At the same time, the phase difference between the output signals of the two delay units is measured one by one from each system by the phase difference meter DMTD. Here, since the digital delay circuit is used as the delay unit, jitter due to the clock in the delay circuit occurs, and an error occurs in the phase measurement. In order to cancel this, the output signals of the two delay units are measured with a phase difference meter DMTD.
That is, the phase difference between the signal from the signal source A and the signal from the signal source B is measured by the phase difference meter DPM. Similarly, the phase difference between the output of the delay unit A and the output of the delay unit B is measured by the phase difference meter DMTD.

  FIG. 8 is a block diagram showing an apparatus configuration for confirming the operation principle of the present invention. In this apparatus configuration, the continuous wave from the signal source A is input to the AD converter α via the delay unit A, the sampling is oversampling, and the signal from the signal source A is used as the sampling signal. Yes. The output of the AD converter α is processed by the CPU-A. Similarly, the continuous wave from the signal source B is input to the AD converter β via the delay unit B, the sampling is oversampling, and the sampling signal is synchronized with the signal from the signal source B. Yes. The output of the AD converter β is processed by CPU-B.

Φ ₁ (t) and Φ ₂ (t) are the phases including the phase fluctuation at the output time t of the signal sources A and B, respectively, and the phase changes due to the delay units A and B themselves are Ψ ₁ (t) and Ψ ₂ ( t), where ΔΘ ₁ (t) and ΔΘ ₂ (t) are the phase differences extracted by CPU-A and B, and τ is the delay time by the delay unit, the following relationship is established.

Further, the outputs Θ _DMTD (t) and Θ _DPM (t) of the phase difference meters DMTD and DPM are as follows.

  Here, from the equations 1 and 2, the following relationship can be obtained.

  In this verification, since the result of Expression 3 matches the lower expression of Expression 2 and the right side, it is confirmed by experiment whether or not the left side of these expressions match.

Here, when Ψ ₁ (t) and Ψ ₂ (t) are zero, it is understood that Θ _DMTD (t) is obtained by delaying Θ _DPM (t) by τ.
At this time, the following equation holds for t = Nτ (N is a natural number).

From the relationship of Equation 4, it can be seen that Φ ₁ (t) including phase variation can be obtained by accumulating the phase difference ΔΘ ₁ (t) and inverting the sign. Φ ₂ (t) can be obtained by the same process.

FIG. 9A shows (a) the difference between the measured values of ΔΘ ₁ (t) and ΔΘ ₂ (t), (b) the measured value of Θ _DMTD (t), and (c) The difference between the measured value difference and (b) Θ _DMTD (t) is shown. FIG. 9B is a moving average obtained by enlarging (c) in the vertical axis direction. FIG. 9C shows the result of the differential phase meter (DPM) in which the result obtained by taking the moving average of FIG. 9B is reprinted and the phase difference between the signal sources A and B is directly measured. Each is a moving average of 10 seconds.
It can be confirmed that the two in FIG. 9 (c) are essentially the same and have a relation of number 3. Therefore, if fluctuation does not occur in the delay characteristics of the delay element, phase fluctuation can be measured based on the above measurement principle.

Since the present invention is a measuring apparatus that evaluates the phase fluctuation of a single spectrum signal from a highly stable signal generator, it can also be used for real-time compensation of high stability of a reference signal of a measuring instrument.
As a result, it is possible to perform continuous measurement with high accuracy for a long time using an independent measurement system, which has been difficult in the past.
For example, meteorological measurement using radio waves measures water vapor fluctuations in the atmosphere as slight propagation fluctuations of radio waves passing through the space. Previously, it was difficult to measure because the component of water vapor fluctuation was buried in the phase fluctuation, but it was possible to measure the water vapor fluctuation by canceling the phase fluctuation using the measurement data of this device, so guerrilla heavy rain Real-time measurement such as (record heavy short-time heavy rain) can be expected.

DESCRIPTION OF SYMBOLS 1 Signal source 2 Delay means 3, 3a, 3b Phase detection means 3a1, 3b1 A / D converter 4 Data processing means 5 Circuit switching means 6 Data processing means 7 Branch means 8 Phase comparison means 9 Control part 10 Signal generation means 11, 12, 13 Frequency conversion means 14 Signal synthesis means 15 Signal generation means 16 A / D converter 17 Delay time measurement / control device

Claims (7)

A signal source that generates a single frequency electrical signal,
Delay means for delaying a signal from the signal source;
Phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source;
Data processing means for connecting the output from the phase detection means at a delay time interval of the delay means, and outputting the accumulated output from the phase detection means,
Circuit switching means for measuring a delay time by the delay means using at least the signal source and the phase detection means;
A phase fluctuation measuring device for measuring a phase drift of the electric signal. The circuit switching means constitutes a circuit bypassing the delay means, and is a first switch means for switching the input of the phase detection means between the delay means and the signal source, from the signal source to the delay means. A second switch means for interrupting the signal of
(1) The first switch means connects the input of the phase detection means and the signal source, closes the second switch means and connects the signal source and the delay means to measure the reference phase,
(2) The second switch means is intermittently determined to obtain a delay time or a delay phase of the delay means.
2. The phase variation measuring apparatus according to claim 1, wherein The configuration for inputting the signal from the signal source to the delay means is as follows.
A signal generating means for generating a signal independently or generating a signal synchronized with the signal from the signal source;
Branching means for branching the signal from the signal generating means into at least a first branch signal and a second branch signal;
And the first branch signal is input to the delay means,
The phase detection means includes
A signal from the delay means to which the first branch signal is input is input to the first phase detection means, a second branch signal is input to the second phase detection means, and the output of the first phase detection means and the second phase detection means Phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source by performing phase comparison of the output of
2. The phase variation measuring apparatus according to claim 1, wherein The configuration for inputting the signal from the signal source to the phase detection means is as follows:
Signal generating means for generating a signal synchronized with the signal from the signal source;
Branching means for branching the signal from the signal generating means into at least a first branch signal and a second branch signal;
Signal combining means for combining the signal obtained by passing the first branch signal through the delay means and the second branch signal;
First frequency converting means for converting the frequency of the signal from the signal generating means with a first frequency signal before inputting the signal to the branching means;
Second frequency conversion means for converting the frequency with a second frequency signal synchronized with the signal from the signal source before inputting the first branch signal to the signal synthesis means;
A third frequency converting means for performing frequency conversion on the output of the signal synthesizing means with a third frequency signal in a manner opposite to that of the frequency conversion of the first frequency converting means;
With
The output of the third frequency conversion means is input to the phase detection means,
The phase detection means includes
The phase from the third frequency converting means is quantized and converted into a digital signal, and the phase detection of the first branch signal and the phase of the second branch signal are simultaneously performed and detected by digital signal processing. Phase detection means for performing phase comparison between the signal from the delay means and the signal from the signal source by performing phase comparison for
2. The phase variation measuring apparatus according to claim 1, wherein   The signal input to the delay unit is once converted into a frequency band usable by the delay unit, and after passing through the delay unit, the frequency conversion and the inverse frequency conversion are performed to return to the original frequency. The phase fluctuation measuring apparatus according to claim 1 or 2. Perform the frequency conversion before entering the branching means,
4. The phase fluctuation measuring apparatus according to claim 3, wherein the inverse frequency conversion is performed after the first branch signal has passed through the branch means and the second branch signal has passed through the delay means.   7. The phase variation measuring apparatus according to claim 3, wherein the signal generating means generates a multicarrier signal synchronized with a signal from the signal source.