RU2703614C1 - Method of measuring phase fluctuations of a harmonic signal and a device for realizing said signal - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: group of inventions relates to measurement equipment and can be used in information-measuring devices for measuring phase (frequency) characteristics of signals of master oscillators, for example, precision quartz oscillators and quantum frequency standards. Method for measuring phase fluctuations of a harmonic signal involves performing analogue-to-digital conversion of a measured signal of a fundamental frequency and a reference signal of a divided frequency with a time sampling interval determined by the sampling frequency of the sampling signal generated from the reference signal, storing digital samples obtained as a result of analog-to-digital conversions, performing digital sample decimation and generating complex digital signals of main and decimated samples, phases of the measured and reference signals are calculated as arguments of the main and decimated complex digital signals and the unknown phase of the measured signal relative the phase of the reference signal is determined. Device implementing the method comprises a measured signal generator, a reference signal generator, a quantization signal frequency synthesizer, a frequency divider, a switch, first and second analogue-to-digital converters, first and second random access memory devices, first and second decimators, a digital signal processing processor connected by a data bus with a personal computer.

EFFECT: technical result consists in improvement of measurement accuracy.

2 cl, 2 dwg

Description

The claimed group of inventions relates to measuring technique and can be used in information-measuring devices for measuring phase (frequency) characteristics of signals of master oscillators, for example, precision crystal oscillators and quantum frequency standards.

The issues of assessing the stability of the phase (frequency) of the signals of the master oscillators are extremely important for achieving the maximum permissible technical characteristics of various radio systems for accuracy and noise immunity and constantly attracts the attention of researchers, see, for example, works: [1] - Falkovich S.E., Khomyakov E. N. / Statistical theory of measuring radio systems // M., Radio and Communications, 1981, p. 117-121; [2] - Equipment for frequency and time measurements / Ed. A.P. Gorshkova // M., Sov. radio, 1971, p. 7-15; [3] (electronic source) http://www.agilent.com - Agilent E5500 Series phase noise measurement solutions, product overview, publication number 5990-5729 RURU.

A number of methods are known for measuring phase fluctuations of harmonic (sinusoidal) signals presented in the patents: [4] - RU 602876 A1, G01R 25/00, 04/15/1978; [5] - RU 995007 A1, G01R 23/00, 02/07/1983; [6] - US 3058063 A, G01R 23/00, 09/10/1962; [7] US 4,378,509 A; H03K 5/26; H03D 13/00, 10/6/1980; [8] - US 6154021 A, G06G 7/19, G01R 25/00, 11.28.2000, however, they are not statistically optimal from the point of view of measuring the phase against the background of noise and fundamentally do not allow to achieve accuracy close to the boundaries determined by the inequality Rao -Kramer. In addition, the implementation of these methods requires a reference signal with a nominal frequency equal to the nominal frequency of the signal under study, the phase stability of which should be several times higher than the measured phase fluctuations. This requirement is not feasible, for example, in the study of signals of highly stable quantum frequency standards.

A number of known methods for measuring phase fluctuations presented in [3, p. 10], as well as in patents: [9] - RU 1765780 A, G01R 23/12, 09/30/1992; [10] - RU 2256928 C2, G01R 23/00, 07.20.2005; [11] - RU 2273859 C1, G01R 29/26, G01R 23/16, 04/10/2006; [12] - RU 2339959 C2, G01R 29/26, 11.27.2008, based on the use of two-channel cross-correlation. This method uses a combination of identical single-channel systems with several (at least two) reference sources whose phase stability can be equal to or even worse than the stability of the signal under study. In this case, cross-correlation operations between the output signals of each channel are performed. The phase noise of the measured signal in each channel is coherent and the cross-correlation operation does not affect their contribution to the measurement result, while the intrinsic noise of each reference signal is not coherent and the cross-correlation operation reduces their total contribution to the measurement result with two reference signals in proportion to M ^0.5 (M is the number of correlations). This can be expressed by the formula:

N _and = N _is + (N ₁ + N ₂ ) / M ^1/2

where: N _and is the total measured noise;

N _IS - noise of the tested device;

N _l and N ₂ - intrinsic noise of the first and second sources of reference signals;

M is the number of correlations.

The method of two-channel cross-correlation allows you to achieve high sensitivity without requiring extremely high characteristics of the reference signals. However, with an increase in the number of correlations, the measurement time increases, which, when evaluating phase noise, whose spectral power density is located near the carrier of the signal under study, turns out to be unacceptably large.

Known methods for measuring the characteristics of phase fluctuations of harmonic signals presented in the patents: [13] - RU 993148 A1, G01R 25/00, 01/30/1983; [14] - RU 1478148 A1, G01R 25/00, 05/07/1989; [15] EP 03793321 A2, G01R 25/00, 07.25.1990; [16] - RU 2041469 C1, G01R 25/00, 09.09.1995; [17] - US 6477214 B1, G01R 23/167, Н04В 1/10, 11/05/2002, based on obtaining the values of the current phase of the signal as an argument of a complex number, followed by the use of phase difference statistics of the signal. These methods are also statistically optimal from the point of view of measuring the phase of the sinusoidal signals against the background of the noise, reaching at large sample sizes the lower Cramer-Rao boundary.

The main disadvantages of this type of methods are:

- their inherent measurement error arising from the difference in the amplitudes of the signals in the quadrature channels, which cannot be realized perfectly identical;

- measurement error due to phase fluctuations ("jitter") of gating pulses;

- the need to use a reference signal whose stability is several times higher than the stability of the measured signal.

In particular, the method for measuring the characteristics of phase fluctuations of a harmonic signal, presented in the patent [13], includes the steps of generating the in-phase and quadrature components of the measured signal, generating the strobe pulses from the reference signal, storing instantaneous values of the in-phase and quadrature components of the measured signal at the moments of the appearance of the strobe pulses, analog-to-digital conversion of the instantaneous values of the in-phase and quadrature components of the measured signal, while the phase is measured the first signal is determined in accordance with the expression:

where: U _s and U _c are the results of analog-to-digital conversion of in-phase and quadrature components, respectively;

k = 1, 2, 3, ... is the current number of the gating pulse.

A significant drawback of this method is its inherent large error of estimation. In fact, the calculated result ϕ (k) contains the following components:

where: ϕ ₀ is the constant phase shift of the measured signal that does not affect the estimated parameter;

θ (k) - phase fluctuations of the measured signal to be evaluated;

θ ₀ (k) - phase fluctuations of the reference signal;

θ _s (k) - spurious phase fluctuations due to the "jitter" of the gating pulses;

θ _a (k) - spurious phase fluctuations due to inaccuracy in setting the equality of amplitudes and phase shift of 90 ° in-phase and quadrature components.

The influence of θ ₀ (k) on the estimation result can be eliminated if θ ₀ (k) ≤≤θ (k), i.e., a reference signal is required whose phase stability is several times greater than the stability of the measured signal. The components θ _s (k) and θ _a (k) are fundamentally inherent in this method and significantly increase the error in estimating the phase fluctuations of the signal under study.

A known method of measuring phase fluctuations of a harmonic signal and a device for its implementation, used in solving problems of determining the characteristics of a harmonic signal, are presented in the patent [18] - RU 2591742 C1, G01R 23/00, 07/20/2016. This method of measuring phase fluctuations of a harmonic signal and a device for its implementation are closest in technical essence to the claimed method and device and are adopted as a prototype.

A method for measuring phase fluctuations of a harmonic signal, adopted as a prototype, is based on a statistically optimal algorithm for estimating the phase of a signal. In this case, the components of the complex signal are formed by successive digital samples of the measured signal, which eliminates the measurement error due to the difference in the amplitudes of the quadrature components of the complex signal.

сигнала дискретизации, формируемого из опорного сигнала с частотой ƒ₀, где j=0, 1, 2, 3, … Образуют и запоминают компоненты комплексного цифрового сигнала U_s(k) и U_c(k), где k=0, 1, 2, 3 … S, осуществляют вычисление фазы ϕ(k) измеряемого сигнала как аргумента комплексного числа в соответствии с выражением ϕ(k)=tg^-1(U_s(k)/U_c(k)). Одновременно осуществляют аналого-цифровое преобразование опорного сигнала с интервалом временной дискретизации, определяемой указанной частотой ƒ_s сигнала дискретизации. Образуют и запоминают компоненты комплексного цифрового опорного сигнала U_0s(k) и U_0c(k), где k=0, 1, 2, 3 … S, осуществляют вычисление фазы ϕ₀(k) опорного сигнала как аргумента комплексного числа в соответствии с выражением ϕ₀(k)=tg^-1(U_0s(k)/U_0c(k)), а искомое отклонение фазы измеряемого сигнала Δϕ(k) относительно фазы опорного сигнала ϕ₀(k) определяют в соответствии с выражением:The method of measuring phase fluctuations of a harmonic signal, adopted as a prototype, is as follows. Perform analog-to-digital conversion of the measured signal with an interval of time sampling, determined by the frequency

a sampling signal generated from a reference signal with a frequency ƒ ₀ , where j = 0, 1, 2, 3, ... Form and store the components of a complex digital signal U _s (k) and U _c (k), where k = 0, 1, 2, 3 ... S, the phase ϕ (k) of the measured signal is calculated as an argument of a complex number in accordance with the expression ϕ (k) = tg ^-1 (U _s (k) / U _c (k)). At the same time, an analog-to-digital conversion of the reference signal is performed with an interval of time sampling determined by the indicated frequency ƒ _{s of} the sampling signal. The components of the complex digital reference signal U _0s (k) and U _0c (k) are formed and stored, where k = 0, 1, 2, 3 ... S, the phase ϕ ₀ (k) of the reference signal is calculated as an argument of a complex number in accordance with the expression ϕ ₀ (k) = tg ^-1 (U _0s (k) / U _0c (k)), and the desired deviation of the phase of the measured signal Δϕ (k) relative to the phase of the reference signal ϕ ₀ (k) is determined in accordance with the expression:

A device for measuring phase fluctuations of a harmonic signal, adopted as a prototype, which implements the prototype method, contains a serially connected measured signal generator, a first analog-to-digital converter, a first random access memory and a digital signal processing processor connected to a data exchange bus with a personal computer, as well as series-connected reference signal generator and frequency synthesizer quantization signal, the output of which is connected to the input sync the first analog-to-digital converter and the synchronization input of the second analog-to-digital converter, the signal input of which is connected to the output of the reference signal generator, and the output through the second random access memory is connected to the second input of the digital signal processing processor, the control output of which is connected to the control input of the frequency synthesizer quantization signal.

In the process of implementing the prototype method, the measured signal generator generates a harmonic signal at its output, which is fed to the signal input of the first analog-to-digital converter.

The reference signal generator generates at its output a harmonic signal with a frequency of ƒ ₀ , which is fed to the signal input of the second analog-to-digital converter, as well as to the signal input of the frequency synthesizer of the sampling signal, to the control input of which there is a signal from the control output of the digital signal processing processor.

The frequency synthesizer of the sampling signal generates a signal, which is a quantizing pulse, the following with a frequency f _s :

where j = 0, 1, 2, 3, ....

The value of the selected index j is introduced through a personal computer into a digital signal processing processor that controls the synthesis coefficient of the synthesizer of the sampling signal frequency in accordance with expression (4).

From the output of the synthesizer of the frequency of the sampling signal, quantizing pulses are fed to the synchronization inputs of the first and second analog-to-digital converters, providing simultaneous formation of digital samples of the measured and reference signals with a sampling frequency ƒ _s .

Digital samples of the measured signal generated using the first analog-to-digital converter with a time interval t _s are stored in the first random access memory.

Digital samples of the reference signal generated using the second analog-to-digital converter with the same time interval t _s are stored in the second random access memory.

In this case, the synthesis of the sampling frequency in accordance with expression (4) ensures the formation of the orthogonal components of the digital complex signals of the measured and reference channels stored in the first random access memory and the second random access memory, respectively.

From the outputs of random access memory devices, digital samples of the measured and reference signals are fed to the corresponding inputs of the digital signal processing processor.

The digital signal processing processor reads the digital codes of the samples of the measured and reference signals, respectively, from the first and second random access memory, generates the sine and cosine components of the digital complex signal of the measured U _s (k), U _c (k) and the reference U _0s (k), U _0c (k) channels, where k = 0, 1, 2, 3 ... S, calculates the phases ϕ (k), ϕ ₀ (k) and the phase deviation of the measured signal in accordance with the expressions:

The calculated values of the phase deviation ϕ (k) of the measured signal are output to a personal computer to indicate the results and statistical processing of individual measurements. In particular, to characterize phase fluctuations, estimates can be obtained:

- variance:

- autocorrelation function:

- power spectral density:

The disadvantage of the prototype method and the prototype device are the relatively low accuracy due to fluctuations in the phase of the reference signal.

The foregoing can be illustrated as follows. The measured value of the dispersion of phase fluctuations contains two components:

- дисперсии фазовых флуктуаций измеряемого и опорного сигналов соответственно.Where

- dispersion of phase fluctuations of the measured and reference signals, respectively.

если выполняется условие:Wherein

if the condition is met:

Otherwise, fluctuations of the reference signal exhibit a masking effect, which unacceptably increases the measurement error. When assessing the phase fluctuations of the signals of precision generators built on atomic-quantum principles, it is impossible to fulfill condition (7).

The technical result, the claimed inventions are aimed at, is to increase the accuracy of measuring phase fluctuations of a harmonic signal by reducing the phase error introduced by the phase instability of the reference signal.

The essence of the proposed method for measuring phase fluctuations of a harmonic signal is as follows. Perform analog-to-digital conversion of signals in the measuring and reference channels with an interval of time sampling, determined by the frequency ƒ _{s of} the sampling signal generated from the reference signal with a frequency of ƒ ₀ . The digital samples obtained as a result of this analog-to-digital conversion are stored in the measuring and reference channels. These digital samples are converted into quadrature components of the complex signals of the measured U _s (k), U _c (k) and the reference U _0s (k), U _0c (k) signals. The phases of the measured ϕ (k) and reference ϕ ₀ (k) signals are determined as arguments of a complex number in accordance with the expressions ϕ (k) = tg ^-1 (U _s (k) / U _c (k)) and ϕ ₀ (k) = tg ^-1 (U _0s (k) / U _0c (k)) and determine the phase Δϕ (k) of the measured signal relative to the phase of the reference signal in accordance with the expression Δϕ (k) = ϕ ₀ (k) -ϕ (k), where k = 0, 1, 2, 3 ... Unlike the prototype, the signal of the reference channel is subjected to the operation of frequency division with the coefficient k _d = 2j + 1 before the analog-to-digital conversion operation, and the frequency ƒ _{s of} the sampling signal is formed in accordance with the expression ƒ _s = 4iƒ ₀ / (2j + 1), where i = 2, 3, 4 , ..., j = 1, 2, 3, ... In addition, the stored digital samples are decimated in the measuring and reference channels with a decimation coefficient i. These decimated digital samples are converted into quadrature components of the complex decimated signals of the measured U _sd (k), U _cd (k) and reference U _0sd (k), U _0cd (k) channels. The phases ϕ _d (k) of the measured decimated signal and ϕ _0d (k) of the reference decimated signal are determined as arguments of a complex number in accordance with the expression ϕ _d (k) = tg ^-1 (U _sd (k) / U _cd (k)) and ϕ _0d (k) = tg ^-1 (U _0sd (k) / U _0cd (k)). The phase Δϕ _d (k) of the measured decimated signal is determined relative to the phase of the reference decimated signal in accordance with the expression Δϕ _d (k) = ϕ _0d (k) -ϕ _d (k), where k = 0, 1, 2, 3 ..., and the desired value of the phase θ * (k) of the measured signal relative to the phase of the reference signal is formed in accordance with the expression θ * (k) = (iΔϕ (k) -Δϕ _d (k)) / (i-1).

The essence of the claimed device for measuring phase fluctuations of a harmonic signal is as follows. The device contains a series-connected generator of the measured signal, the first analog-to-digital converter, the first random access memory and a digital signal processor connected to the data bus with a personal computer, as well as a series-connected reference signal generator and a frequency synthesizer of the quantization signal, the output of which is connected to synchronization input of the first analog-to-digital converter and synchronization input of the second analog-to-digital converter I, the output of which through a second random access memory coupled to the second input of the digital signal processing, the control output of which is connected with the control input of quantization synthesizer frequency signal. Unlike the prototype, the device contains a frequency divider, the output of which is connected to the signal input of the second analog-to-digital converter, the control input is connected to the control input of the synthesizer of the quantization signal frequency, and the signal input is connected to the output of the switch, the first and second inputs of which are connected, respectively, with the output of the reference signal generator and the output of the measured signal generator, as well as the first decimator, the input of which is connected to the output of the first random access memory, and the output - with the third input of the digital signal processing processor, and a second decimator, the input of which is connected to the output of the second random access memory, and the output - with the fourth input of the digital signal processing processor.

The essence of the claimed method and device is illustrated by the illustrative materials presented in FIG. 1 and 2, where:

in FIG. 1 is a structural diagram of a device for measuring phase fluctuations of a harmonic signal, with the help of which the inventive method for measuring phase fluctuations of a harmonic signal is carried out;

in FIG. 2 shows in a schematic form the transformation of the spectrum of the measured signal during its time sampling.

The inventive device for measuring phase fluctuations of a harmonic signal that implements the inventive method for measuring phase fluctuations of a harmonic signal, contains, see FIG. 1, the measured signal generator 1, the first analog-to-digital converter 2, the first random access memory 3 and the digital signal processing processor 4 connected to the data exchange bus with a personal computer 5 in series.

The control output of the digital signal processing processor 4 is connected to the control input of the synthesizer 6 of the quantization signal frequency, the signal input of which is connected to the output of the reference signal generator 7, and the output is connected to the synchronization input of the first analog-to-digital converter 2 and the synchronization input of the second analog-to-digital converter 8.

The output of the second analog-to-digital converter 8 is connected to the input of the second random access memory 9, the output of which is connected to the second input of the digital signal processing processor 4. The signal input of the second analog-to-digital converter 8 is connected to the output of the frequency divider 10.

The control input of the frequency divider 10 is connected to the control input of the synthesizer 6 of the quantization signal frequency, connected to the control output of the digital signal processing processor 4.

The signal input of the frequency divider 10 is connected to the output of the switch 11, the first input of which is connected to the output of the reference signal generator 7, and the second input is connected to the output of the measured signal generator 1. The switch 11 has two fixed positions. In the first position, the switch 11 provides the connection of the input of the frequency divider 10 with the output of the reference signal generator 7, and in the second position, the connection of the input of the frequency divider 10 with the output of the measured signal generator 1. The switch 11 can be controlled manually or from a personal computer 5 through a digital signal processing processor 4 (this relationship is not indicated in Fig. 1).

The output of the first random access memory 3 is also connected to the input of the first decimator 12, the output of which is connected to the third input of the digital signal processing processor 4.

The output of the second random access memory 9 is also connected to the input of the second decimator 13, the output of which is connected to the fourth input of the digital signal processing processor 4.

The inventive device for measuring phase fluctuations of a harmonic signal allows two types of measurements. The first view is the measurement of the phase fluctuations of the signal of the generator 1 by measuring the actual value of the phase difference (frequency) of this signal relative to the reference signal generated by the generator 7. The second view is the measurement of only the fluctuation component of the phase of the measured signal of the generator 1 (phase and frequency stability), then there is a measurement of the spectral power density of the phase fluctuation (dispersion) of the signal of the generator 1 itself. The first type of measurement is carried out when the switch 11 is installed in the first position, W swarm measurement type - with switch 11 to the second position.

The operation of the inventive device for measuring phase fluctuations of a harmonic signal, illustrating the feasibility of the proposed method for measuring phase fluctuations of a harmonic signal, is as follows.

The generator 1 of the measured signal and the generator 7 of the reference signal form harmonic signals at their outputs, the models of which are presented respectively in the form:

Where:

ƒ - nominal value of the frequency of the measured and reference signals;

- функции фазы соответственно измеряемого и опорного сигналов, содержащие детерминированную и флуктуационные части.

- phase functions of the measured and reference signals, respectively, containing the deterministic and fluctuation parts.

I.e:

подлежат измерению относительно

Поэтому можно положить

а наличие

приводит к погрешности измерения

(см. выражение (7)). С учетом этих замечаний правое соотношение в выражении (8) может быть переписано в видеBoth components

subject to measurement relative

Therefore, we can put

and availability

leads to measurement error

(see expression (7)). With these comments in mind, the right relation in expression (8) can be rewritten in the form

In the case of measuring phase fluctuations of the signal of the generator 1 by measuring the actual value of the phase difference (frequency) of this signal relative to the reference signal generated by the generator 7, the reference signal through the switch 11, located in the first position, is fed to the frequency divider 10, which generates at its output, and, therefore, at the signal input of the second analog-to-digital Converter 8, the signal is determined by the expression:

с выходов генератора 1 и делителя 10 частоты поступают на сигнальные входы аналого-цифровых преобразователей 2 и 8, где подвергаются синхронному квантованию по уровню с интервалом временной дискретизации t_s, длительность которого задается синхроимпульсами, поступающими с выхода синтезатора 6 частоты сигнала квантования. Длительность интервала временной дискретизации t_s равна:Signals u (t) and

from the outputs of the generator 1 and the frequency divider 10 are fed to the signal inputs of analog-to-digital converters 2 and 8, where they are subjected to synchronous quantization in level with an interval of time sampling t _s , the duration of which is set by sync pulses from the output of the synthesizer 6 of the quantization signal frequency. The duration of the time sampling interval t _s is equal to:

where: j = 1, 2, 3, ..., i = 2, 3, 4, ...

The selected values of indices j and i indicated in expressions (10) and (11) that specify the division coefficient of the frequency divider 10 and the parameters of the time interval of the synthesizer 6 of the frequency of the quantization signal are input through a personal computer 5 into the digital signal processing processor 4, which controls the work of the frequency divider 10 and synthesizer 6 of the frequency of the quantization signal.

The synthesizer 6 of the frequency of the quantization signal is synchronized by the signal from the output of the generator 7 of the reference signal, and generates a signal u _s (t):

- фазовые флуктуации сигнала синтезатора 6 частоты сигнала квантования.Where

- phase fluctuations of the synthesizer signal 6 frequency of the quantization signal.

Let the quantization signal pulses form at the moments of transition through the zero level with the positive derivative of the signal defined by expression (12). Then the moments t _k samples in the first analog-to-digital Converter 2 and the second analog-to-digital Converter 8 can be determined from the equation:

where k = 0, 1, 2, 3, ... is the current number of samples.

Therefore, taking into account expression (11), we have:

where Δ _s (k, j, i) - represents the "jitter" of the sample moments due to phase fluctuations of the synthesizer signal 6 of the frequency of the quantization signal, defined by the expression:

Expressions for digital samples of the measured and reference signals, which are stored later in random access memory 3 and 9, can be written if in expressions (8) and (10) instead of continuous time t substitute t _k from expression (13) taking into account expression (11) :

… - целое четное число (например, i=2, j=8). В этом случае выражение (15) может быть переписано в виде:There is some arbitrariness for choosing the values of j and i. Therefore, you can require

... is an even integer (for example, i = 2, j = 8). In this case, expression (15) can be rewritten in the form:

A comparison of expressions (16) and (17) shows that in random access memory 3 and 9, digital samples of signals are accumulated with the same relative center frequency ω ₀ = 2πƒ / ƒ _s = π / 2i (see Fig. 2a), with the only difference is that in the measuring channel, which includes the first random access memory 3, the accumulation of samples is the result of a stroboscopic effect (Fig. 2b), and in the reference channel, which includes the second random access memory 9, is the result of direct quantization of the reference signal divided by a factor (2j + 1) of the frequency from the output of the frequency divider 10 (Fig. 2B). In this case, as illustrated in FIG. 2, the width of the spectrum of the measured signal does not change during digital conversion to the frequency ω ₀ (Fig. 2b), and the spectrum of the reference signal narrows (2j + 1) times (Fig. 2c), since the relative width of the spectrum during the division of the signal frequency is not is changing.

с выхода второго оперативного запоминающего устройства 9 поступают соответственно на первый и второй входы процессора 4 цифровой обработки сигналов, а также на входы соответствующих дециматоров 12 и 13.Digital signals u (k) from the output of the first random access memory 3 and signals

from the output of the second random access memory 9, respectively, are supplied to the first and second inputs of the processor 4 for digital signal processing, as well as to the inputs of the corresponding decimators 12 and 13.

соответственно:The decimation procedure is defined as digital processing of the input signal using linear filtering, as a result of which an output signal is generated with a sampling rate reduced by i times (see, for example, patent [17] and publication [19] - Fundamentals of digital signal processing. Lecture course / A .I. Solonina et al. // Publishing House 2nd ed. And rev., St. Petersburg, BHV-Petersburg, 2005, p. 589-615). Therefore, at the third and fourth inputs of the digital signal processing processor 4, digital codes u _d (k) and

respectively:

The processor 4 of the digital signal processing performs the following operations.

на значения

и

, а выборок u_d(k),

- назначения

и

с последующей цифровой низкочастотной фильтрацией, то есть:Firstly, the formation of quadrature components of the complex signals of the measured U _s (k), U _c (k) and the reference U _0s (k), U _0c (k) channels, as well as the quadrature components of the complex decimated signals of the measured U _sd (k) , U _cd (k) and reference U _0sd (k), U _0c (k) channels. This formation is performed, for example, by multiplying the samples u (k) and

to values

and

, and the samples u _d (k),

- destination

and

followed by digital low-pass filtering, that is:

Secondly, the phases of the measured θ (k) and reference θ ₀ (k) signals are determined, as well as the phases θ _d (k) of the measured decimated signal and θ _0d (k) of the reference decimated signal as arguments of complex numbers in accordance with the expressions:

Thirdly, the phase Δϕ (k) of the measured signal relative to the phase of the reference signal and the phase Δϕ _d (k) of the measured decimated signal relative to the phase of the reference decimated signal are calculated in accordance with the expressions:

Fourthly, the phase estimate θ * (k) of the measured signal is calculated in the form of:

The first term on the right-hand side of expression (20), taking into account expression (14), is equal to zero, therefore, the desired estimate of the phase θ * (k) of the measured signal is defined as:

Thus, when performing measurements of phase fluctuations of the measured signal by the claimed method and device, compensation of the measurement error due to phase fluctuations of the synthesizer 6 of the frequency of the quantization signal is provided, while the masking effect of the phase fluctuations of the reference signal, in contrast to the prototype, is reduced (2j + 1) times . For example, for the practical case j = 8, the gain is exactly 17 times. This means that condition (7) is easily satisfied even when the phase stability of the reference signal is several times worse than that of the measured signal.

The values of the phase θ * (k) of the measured signal calculated in this way are then output to a personal computer 5 for indicating the results and statistical processing of individual measurements, for example, in accordance with expression (6).

In the case when only the fluctuation component of the phase of the measured signal is subject to measurement (phase and frequency stability), the switch 11 is set to its second position, in which the signal from the measured signal generator 1 is transmitted to the input of the frequency divider 10, in other words, in the reference channel as a reference signal the measured signal itself is used.

имеет вид:For this case, expression (21), taking into account the obvious relation

has the form:

The calculation of the phase value θ ** (k) of the measured signal is carried out similarly to the case considered above in the digital signal processing processor 4. The calculated values of the phase θ ** (k) of the measured signal are output to a personal computer 13 for indicating the results and statistical processing of individual measurements, for example, in accordance with expression (6).

The above shows that the claimed group of inventions is feasible and ensures the achievement of a technical result, which consists in improving the accuracy of measuring phase fluctuations of a harmonic signal.

Information sources

1. Falkovich S.E., Khomyakov E.N. / Statistical theory of measuring radio systems // M., Radio and Communications, 1981, p. 117-121.

2. Equipment for frequency and time measurements / Ed. A.P. Gorshkova // M, Sov. radio, 1971, p. 7-15.

3.Http: //www.agilent.com_Agilent E5500 Series phase noise measurement solutions, product overview, publication number 5990-5729 RURU.

4. RU 602876 A1, G01R 25/00, 04/15/1978.

5. RU 995007 A1, G01R 23/00, 02/07/1983.

6. US 3058063 A, G01R 23/00, 09/10/1962.

7. US 4378509 A, H03K 5/26, H03D 13/00, 10/06/1980.

8. US 6154021 A, G06G 7/19, G01R 25/00, 11.28.2000.

9. RU 1765780 A, G01R 23/12, 09/30/1992.

10. RU 2256928 C2, G01R 23/00, 07.20.2005.

11. RU 2273859 C1, G01R 29/26, G01R 23/16, 04/10/2006.

12. RU 2339959 C2, G01R 29/26, 11.27.2008.

13. RU 993148 A1, G01R 25/00, 01/30/1983.

14. RU 1478148 A1, G01R 25/00, 05/07/1989.

15. EP 03793321 A2, G01R 25/00, 07.25.1990.

16. RU 2041469 C1, G01R 25/00, 08/09/1995.

17. US 6477214 B1, G01R 23/167, H04B 1/10, 11/05/2002.

18. RU 2591742 C1, G01R 23/00, 07.20.2016.

19. Basics of digital signal processing. The course of lectures / A.I. Corned beef and others // Ed. 2nd fix and revised., St. Petersburg, BHV-Petersburg, 2005, p. 589-615.

Claims (2)

1. A method for measuring phase fluctuations of a harmonic signal, in which analog-to-digital conversion of signals in the measuring and reference channels is carried out with a time sampling interval determined by the frequency ƒ _{s of} the sampling signal generated from the reference signal with a frequency of ƒ ₀ , and the resulting analog digital conversion digital samples in the measuring and reference channels, these digital samples are converted into quadrature components of the complex signals of the measured U _s (k), U _c (k) and reference U _0s (k), U _0c (k) signals, determine the phases of the measured ϕ (k) and reference ϕ ₀ (k) signals as arguments of a complex number in accordance with the expressions ϕ (k) = tg ^-1 (U _s (k) / U _c (k)) and ϕ ₀ (k) = tg ^-1 (U _0s (k) / U _0c (k)) and determine the phase Δϕ (k) the measured signal relative to the phase of the reference signal in accordance with the expression Δϕ (k) = ϕ ₀ (k) -ϕ (k), where k = 0, 1, 2, 3 ..., characterized in that the signal of the reference channel before the analog-to-digital operation transformations are subjected to frequency division operations with the coefficient k _d = 2j + 1, and the frequency ƒ _{s of} the sampling signal is formed in accordance with vii with the expression ƒ _s = 4iƒ ₀ / (2j + 1), where i = 2, 3 4, ..., j = 1, 2, 3, ..., in addition, the stored digital samples are decimated in the measuring and reference channels with a coefficient decimations i, convert these decimated digital samples into quadrature components of complex decimated signals of the measured U _sd (k), U _cd (k) and reference U _0sd (k), U _0cd (k) channels, determine the phases ϕ _d (k) of the measured decimated the signal and ϕ _0d (k) of the reference decimated signal as arguments of a complex number in accordance with the expressions ϕ _d (k) = tg ^-1 (U _sd (k) / U _cd (k)) and ϕ _{0 d} (k) = tg ^-1 (U _0sd (k) / U _0cd (k)) and determine the phase Δϕ _d (k) of the measured decimated signal relative to the phase of the reference decimated signal in accordance with the expression Δϕ _d (k) = ϕ _0d ( k) -ϕ _d (k), where k = 0, 1, 2, 3 ..., and the desired value of the phase θ * (k) of the measured signal relative to the phase of the reference signal is formed in accordance with the expression θ * (k) = (iΔϕ ( k) -Δϕ _d (k)) / (i-1). 2. A device for measuring phase fluctuations of a harmonic signal, comprising a series-connected generator of the measured signal, a first analog-to-digital converter, a first random access memory and a digital signal processing processor connected by a data exchange bus with a personal computer, as well as a series-connected reference signal generator and a synthesizer of the frequency of the quantization signal, the output of which is connected to the synchronization input of the first analog-to-digital converter and a synchronization input of a second analog-to-digital converter, the output of which through the second random access memory is connected to the second input of the digital signal processor, the control output of which is connected to the control input of the synthesizer of the quantization signal frequency, characterized in that it contains a frequency divider, the output of which is connected to the signal the input of the second analog-to-digital converter, the control input is connected to the control input of the synthesizer of the frequency of the quantization signal, and the signal input connected to the output of the switch, the first and second inputs of which are connected respectively to the output of the reference signal generator and the output of the measured signal generator, as well as the first decimator, the input of which is connected to the output of the first random access memory, and the output to the third input of the digital signal processing processor, and the second decimator, the input of which is connected to the output of the second random access memory, and the output to the fourth input of the digital signal processor.

Images