RU2613865C2 - Clock synchronisation method and device therefor - Google Patents

Abstract

FIELD: radio engineering and communication; radar and radio navigation.

SUBSTANCE: proposed method and device relate to communication engineering and radar and can be used for comparison of time scales spaced apart over long distances. Device which realises disclosed method of synchronising clocks, comprises a relay artificial earth satellite, first A and second B ground stations, each having time and frequency standard 1, unit 2 heterodynes: first 2.1, second 2.2 and third 23 heterodynes, multiplier 4, mixers 5, 13 and 24, first intermediate frequency amplifier 6, power amplifiers 7 and 12, duplexer 8, transceiving antenna 9, pseudorandom signal generator 3, clippers 10 and 15, buffer storage devices 11 and 16, correlators 17 and 26, controlled delay unit 18, multipliers 19 and 29, low-pass filter 20, extreme controller 21, microprocessor 22, second intermediate frequency amplifiers 14 and 25, threshold unit 27, switch 28, phase doubler 30, narrow-band filters 31 and 32, phase detector 33 and inverting amplifier 34.

EFFECT: engineering problem of invention is increasing noise immunity and accuracy of synchronising remote time scales by providing symmetry of frequencies f_H2 and f_H3 of second and third heterodynes relative to frequency f₂ of main receiving channel f_U2-f₂=f₂-f_H3=f_pr2.

2 cl, 4 dwg

Description

The proposed method and device relate to communication and radar technology and can be used to compare time scales spaced over long distances.

Known methods and devices for clock synchronization (ed. Certificate of the USSR No. 591799, 614.416, 970.300, 1.180.835, 1.244.632, 1.278.800; RF patents No. 2.001423, 2.003.157, 2.040.035, 2.146.833, 2.177.167, 2.310.221, 2.350.998; 2.383.914, 2.539.914; US patent No. 7.327.699, 7.426.156; UK patent No. 1.517.661; German patent No. 3.278.943; EP patent No. 0.564. 220; Gubanov BC, Finkelstein AM, Friedman P.A. Introduction to radio astrometry. - M., 1983 and others).

Of the known methods and devices closest to the proposed is the "Method of clock synchronization and a device for its implementation" (RF patent No. 2.539.914, G04C 11/00, 2013), which are selected as prototypes.

The known method and device provide a comparison of time scales spaced over long distances and are based on the use of the duplex communication method through a geostationary satellite repeater and correlation processing of noise-like signals.

In this case, the suppression of false signals (interference) received via mirror and Raman channels is based on the use of two local oscillators 22 and 23, the frequencies f _Г2 and f _{Г3 of} which are spaced by twice the value of the second intermediate frequency (Fig. 4).

f _G2 -f _G3 = 2f _pr2

and are selected symmetrical with respect to frequency f _{2 of the} main receiving channel

f ₂ -f _G3 = f _G2 -f ₂ == f _pr2 .

This circumstance leads to a doubling of the number of additional receiving channels, but creates favorable conditions for their suppression due to the correlation processing of channel voltages.

However, under the influence of various destabilizing factors, including the Doppler effect, when the satellite repeater makes certain movements relative to the assumed stable position, the indicated symmetry is broken and the noise immunity and accuracy of synchronization of remote time scales are reduced.

An object of the invention is to increase the noise immunity and accuracy of synchronization of remote time scales by ensuring the symmetry of the frequencies f _G2 and f _{G3 of the} second and third local oscillators relative to the frequency f _{2 of the} main receiving channel

f ₂ -f _G3 = f _G2 -f ₂ == f _pr2 .

The problem is solved in that the method of clock synchronization, based, in accordance with the closest analogue, on the simultaneous reception by spaced ground points of noise-like microwave signals from an artificial Earth satellite, coherently converting them to a video frequency, digitally recording the received signals and determining the time delay of arrival of one of the same signal to synchronization points by the method of correlation processing of registered signals, the magnitude of which compares time scales, while at initial time t ₁ to the clock of the first item using the code sequences form a noise-like microwave signal is recorded it at the same point, the conditioned signal is converted to a frequency f _1, increase its power emit the amplified signal toward the artificial satellite - repeater in the same time point t _1, the clock of the second item with the same code sequence form the same noise-like microwave signal, it is recorded in the second paragraph, taking onboard equipment retro-hIS slyatora signal at frequency f _1, re-emit it at first and second points at the frequency f ₂ while preserving phase relationships, at an arbitrary time t ₃ by the clock of the second paragraph similarly formed and recorded noise-like microwave signal generated signal is converted to f ₁ frequency, amplify it in power, emit an amplified signal in the direction of the same satellite repeater, at the same time t _3, according to the clock of the first point, using the same code sequence form the same noise-like microwave signal, register it on the first paragraph, take on-board equipment of the satellite repeater signal at a frequency f ₁ and re-emit it to the first and second points at a frequency f ₂ while maintaining phase relationships, the registered probe signal is passed through an adjustable delay unit, multiply it with the registered relay signal, the low-frequency voltage is isolated thereby forming the correlation function R (τ), where τ is the current time delay, by varying the delay τ, the correlation function R (τ) is maintained at the maximum level, fixing there is a time delay τ _i (i = 1, 2, 3, 4) between two pairs of registered probing and relay signals, the magnitude of which is used to compare time scales, while the received signal at the carrier frequency f _{2 is} converted in frequency using frequencies f _g2 and f _{g3 of the} second and third local oscillators, which are carried at twice the value of the second intermediate frequency

f _g2 -f _g3 = 2f _pr2

and choose symmetrical with respect to frequency f _{2 of the} main receiving channel

f ₂ -f _r3 = f _r2 -f ₂

emit a voltage of the second intermediate frequency

_np2 f = f ₂ -f _r3 and _np2 f = f _r2 -f ₂

subjected to correlation processing, form voltage U (τ) proportional to the correlation function R (τ), compare it with a threshold voltage and, if it is exceeded, form a constant voltage, which is used to resolve further processing of the first voltage of the second intermediate frequency, differs from the closest analogue the fact that the voltage of the second and third local oscillators is multiplied among themselves, the first narrow-band voltage of the doubled second intermediate frequency is isolated, the phase of the first voltage is doubled of the second intermediate frequency, the second narrowband voltage of the doubled second intermediate frequency is isolated, the first and second narrowband voltage of the doubled second intermediate frequency are compared in phase, the control voltage of positive or negative polarity is formed, they act on the control inputs of the local oscillators so that they are symmetric with respect to the frequency f ₂ main receiving channel

f ₂ -f _r3 = f _r2 -f ₂ = f _np2.

The problem is solved in that the clock synchronization device, containing, in accordance with the closest analogue, an AES repeater, first and second ground stations, each of which contains a time and frequency standard connected in series, a first local oscillator, a first mixer, the second input of which is through a switch connected to the first output of the pseudo-random signal generator, an amplifier of the first intermediate frequency, a first power amplifier, a duplexer, the input-output of which is connected to a transceiver antenna, the second amplifier power, a second mixer, the second input of which is connected through the second local oscillator to the first output of the time and frequency standard, and the first amplifier of the second intermediate frequency, the second clipper connected in series, the second input of which is connected to the third output of the time and frequency standard, the second memory unit and the first correlator, while the first clipper is connected to the second output of the pseudo-random signal generator, the second input of which is connected to the second output of the time and frequency standard and the first memory block One of which is connected to the second input of the first correlator, which is made in the form of a variable delay unit, a multiplier, connected in series to the output of the first memory block, the second input of which is connected to the output of the second memory block, low-pass filter and extreme controller, the output of which is connected to the second input of the adjustable block delays, to the second output of which the microprocessor is connected to the output of the second power amplifier, a third mixer is connected in series, the second input of which is connected to the output the third local oscillator, the second amplifier of the second intermediate frequency, the second correlator, the second input of which is connected to the output of the first amplifier of the second intermediate frequency, the threshold unit and the key, the second input of which is connected to the output of the first amplifier of the second intermediate frequency, and the output is connected to the first input of the second clipper , frequencies f _g2 and f _{g3 of the} second and third local oscillators are spaced twice the value of the second intermediate frequency

f _g2 -f _g3 = 2f _pr2

and are selected symmetrical with respect to frequency f _{2 of the} main receiving channel

f ₂ -f _r3 = f _r2 -f ₂ = f _np2,

differs from the closest analogue in that it is equipped with a second multiplier, two narrow-band filters, a phase doubler, a phase detector and an inverse amplifier, with a second multiplier connected in series to the output of the second local oscillator, the second input of which is connected to the output of the third local oscillator, the first narrow-band filter, phase detector , an inverse amplifier, the first and second outputs of which are connected to the control inputs of the second and third local oscillators, respectively, a phase hunter and a second narrow-band filter, the output of which is connected to the second input of the phase detector.

The geometric arrangement of ground points A, B and the satellite repeater S is shown in FIG. 1, where the following notation is introduced:

O - Earth's center of mass; d is the base of the interferometer; r is the radius vector of the satellite. The time diagram of the duplex method of comparing watches is presented in figure 2, where the following notation is introduced: S, A, B - time scale of the satellite relay and points A and B, respectively. A block diagram of a clock synchronization device that implements the proposed method for clock synchronization is shown in FIG. 3. A frequency diagram illustrating signal conversion is shown in FIG. four.

The clock synchronization device contains a satellite repeater, the first A and second B ground stations, each of which contains a time and frequency standard 1 connected in series, the first local oscillator 2.1, the first mixer 5, the second input of which is connected through the switch 4 to the first output of the pseudo-noise signal generator 3 , an amplifier 6 of a first intermediate frequency, a first power amplifier 7, a duplexer 8, the input-output of which is connected to a transceiver antenna 9, a second power amplifier 12, a second mixer 13, the second input of which is connected without a second local oscillator 2.2 with a first output of the time and frequency reference 1, and a first amplifier 14 of the second intermediate frequency, a second clipper 15 connected in series, the second input of which is connected to the third output of the time and frequency reference 1 and the first memory block 16, the output of which is connected to the second the input of the first correlator 17. In this case, the first clipper 10 is connected to the second output of the pseudo-random signal generator 3, the second input of which is connected to the second output of the time and frequency standard 1, and the first memory block 11, the output which is connected to the second gate of the first correlator 17, which is made in the form of series-connected to the output of the first block 11 of the memory of the block 18 adjustable delay, the first multiplier 19, the second input of which is connected to the output of the second block 16 of the memory filter 20 low pass and extreme controller 21, the output of which is connected to the second input of the adjustable delay unit 18, the microprocessor 22 is connected to the second output of which. A third mixer 24 is connected in series to the output of the second power amplifier 12, the second input for which through the third local oscillator 23 is connected to the first output of the time and frequency standard 1, the second amplifier 25 of the second intermediate frequency, the second correlator 26, the second input of which is connected to the output of the first amplifier 14 of the second intermediate frequency, the threshold unit 27 and the key 28, the second input of which connected to the output of the first amplifier 14 of the second intermediate frequency, and the output is connected to the first input of the second clipper 15. To the output of the second local oscillator 2.2, a second multiplier 29 is connected in series, the second input of which is connected to the output t a local oscillator 23, a first narrow-band filter 31, a phase detector 33 and an inverse amplifier 34, the first and second outputs of which are connected to the control input of the second 2.2 and third 23 local oscillators, respectively. To the output of the key 28, a phase doubler 30 and a second narrow-band filter 32 are connected in series, the output of which is connected to the second input of the phase detector 33. Clock synchronization by the proposed method is as follows:

по часам первого пункта А с помощью кодовой последовательности формируют шумовой СВЧ-сигнал (сигнал α₁);- at time

by the clock of the first point A using a code sequence form a noise microwave signal (signal α ₁ );

- register it at the same point;

- the generated signal is converted to a frequency f ₁ ;

- reinforce it in power;

- emit an amplified signal in the direction of the satellite repeater;

по часам второго пункта В с помощью той же кодовой последовательности формируют такой же шумовой СВЧ-сигнал (сигнал β₁);- at the same time

by the clock of the second point B using the same code sequence form the same noise microwave signal (signal β ₁ );

- register it at the second point B (signal β ₁ , which, however, is not sent for relay);

- take on-board equipment of the satellite repeater signal at a frequency f ₁ (signal α ₁ );

- re-emit it at points A and B at a frequency f ₂ while maintaining phase relationships in the interval t _c ;

- receive a relay signal at both points;

- convert it to a video frequency;

и

соответственно (сигналы α₂, β₂);- register it at time points

and

respectively (signals α ₂ , β ₂ );

по часам второго пункта аналогично формируют и регистрируют шумовой СВЧ-сигнал (сигнал β₃);- at any time

according to the clock of the second point, a noise microwave signal (signal β ₃ ) is formed and recorded in a similar manner;

- the generated signal is converted to a frequency f ₁ ;

- reinforce it in power;

- emit an amplified signal in the direction of the same satellite repeater;

по часам первого пункта А с помощью той же кодовой последовательности формируют такой же шумовой СВЧ-сигнал (сигнал α₃);- at the same time

by the clock of the first point A using the same code sequence form the same noise microwave signal (signal α ₃ );

- register it at the first point A (signal α ₃ , which, however, is not relayed);

- take the on-board equipment of the satellite repeater signal at a frequency f ₁ (signal α ₃ );

- re-emit it to points A and B at a frequency f ₂ while maintaining phase relationships;

- receive a relay signal at both points;

- convert it to a video frequency;

и

соответственно (сигналы α₄, β₄).- register at time points

and

respectively (signals α ₄ , β ₄ ).

The correlation processing of two pairs of registered signals in the meter 17 determines at each point the following time delays:

and the corresponding interference frequencies F _i (i = l, 2, 3, 4), which determine the derivatives of these delays:

,

,

;Where

;

a _j , b _l (j = 1, 2, 3) - signal propagation time between the satellite and points A and B, respectively (Fig. 1);

,

- задержки сигналов в излучающей аппаратуре обоих пунктов;

,

- signal delays in the radiating equipment of both points;

,

- задержки сигналов в приемо-регистрирующей аппаратуре;

,

- signal delays in the receiving and recording equipment;

Δs - signal delay in the aircraft satellite repeater;

Δt = t _B -t _A is the desired difference in the clock readings at the same physical moment;

получаем:Assuming a _j and b _j linear functions with derivatives

we get:

Where

,

- задержки сигнала в атмосфере на частотах f₁ и f₂ соответственно;

,

- signal delay in the atmosphere at frequencies f ₁ and f _2, respectively;

ν - relativistic correction (Sagnac effect);

c is the speed of light;

ω is the angular velocity of the Earth;

D - the area of the quadrangle OA'SB ', formed in the equatorial plane by the center of mass of the Earth, the projections of points A and B and

Satellite repeater.

The correction γ for the mobility of the satellite repeater in time of a single measurement is most easily reduced to zero by the corresponding choice of the free parameter θ:

which should be calculated at the beginning of measurements by approximate ephemeris data, and then clarified by the results of current measurements. As for the correction δ for hardware delays, it can be found by calibration using the “zero base” method.

The atmospheric correction ε is also taken into account.

Let us estimate the errors in the measurement of time delays τ _i (i = 1, 2, 3, 4).

The radio interferometric signal-to-noise ratio is

and the errors in measuring the time delay τ and interference frequency F have the form

where Δf is the band of received and recorded frequencies of the pseudo-noise signal;

P _with , P _W - signal power and noise at the input of the receiver;

t _c is the coherence interval of the signal when it is relayed.

. Например, при

получаем Q≥500, что вполне достижимо даже при использовании наземных приемо-передающих антенн малого диаметра.Then, to obtain the error στ = 0.1 ns, it is necessary that

. For example, when

we get Q≥500, which is quite achievable even with the use of small diameter terrestrial transmitting and receiving antennas.

и

согласно (4) оказывается достаточным и t_с=5 10^-6 с. Как легко показать, такое время когерентности обеспечивается уже при нестабильности гетеродина бортового ретранслятора

.For Q = 500,

and

according to (4) it turns out to be sufficient and t _s = 5 10 ^-6 s. It is easy to show that such a coherence time is ensured even with the instability of the onboard repeater local oscillator

.

, поэтому для вычисления γ с ошибкой 0,1 нс необходимо F знать с ошибкой σ_F=3 Гц. Тогда, используя формулы (4) и (5), получаем t_c=0,4⋅10^-3, что требует более высокой стабильности бортового гетеродина

.As for the error in measuring the interference frequency F, when using an artificial satellite geostationary as a repeater, the following restrictions are usually fulfilled:

therefore, to calculate γ with an error of 0.1 ns, it is necessary to know F with an error of σ _F = 3 Hz. Then, using formulas (4) and (5), we obtain t _c = 0.4⋅10 ^-3 , which requires higher stability of the onboard local oscillator

.

The principle of operation of the equipment is as follows.

In the first step of single measurements, the pseudo-noise signal α ₁ (Fig. 2) created by the generator 3 using the standard 1 frequency and time

where U _c , f _c , ϕ _c , T _c - amplitude, carrier frequency, initial phase and signal duration;

ϕ _k (t) = {0, π} is the manipulated phase component that displays the phase manipulation law in accordance with the code sequence M (t), and ϕ _k (t) = const or kτ _e <t <(k + 1) τ _e and can change abruptly at t = kτ _E , i.e. at the borders between elementary premises (k = 1, 2, ..., N-1);

τ _E , N is the duration and number of chips that make up the signal of duration T _c (T _c = Nτ _E ).

The specified signal is input to the clipper 10, and then registered in the buffer memory 11. Registration is synchronized by standard 1 frequency and time.

The generated signal u _c (t) through a closed switch 4 is fed to the first input of the first mixer 5, the second input of which is supplied with the voltage of the first local oscillator 2.1

At the output of the mixer 5, voltages of combination frequencies are generated. Amplifier 6 distinguishes the voltage of the first intermediate (total) frequency

;Where

;

f _CR1 = f _G1 + f _c - the first intermediate (total) frequency;

ϕ _pr1 = ϕ _G1 + ϕ _s ,

which after amplification in the power amplifier 7 through the duplexer 8 enters the transceiver antenna 9 and is radiated by it in the direction of the satellite-relay at a frequency f ₂ = f _pr1 .

по часам второго пункта В с помощью той же кодовой последовательности M(t) формируют такой же шумоподобный СВЧ-сигнал (сигнал β₁). Регистрируют его на втором пункте В (сигнал β₁, который, однако, не отправляется на регистрацию).At that moment in time

by the clock of the second point B using the same code sequence M (t) form the same noise-like microwave signal (signal β ₁ ). Register it at the second paragraph (signal β ₁ , which, however, is not sent for registration).

Received onboard equipment of the satellite repeater at a frequency of f ₁ (signal α ₁ ), re-emit it to points A and B at a frequency of f ₂ while maintaining phase components in the interval t _c .

Relay signal (signal α ₁ ) at a frequency f ₂

received by the transmit-receive antenna 9 and through the duplexer 8 and the power amplifier 12 is supplied to the first inputs of the second 13 and third 24 mixers. The second inputs of the mixers 13 and 24 are fed respectively to the voltage of the local oscillators 22 and 23:

Moreover, the frequencies f _Г2 and f _{Г3 of} these local oscillators are spaced twice the second intermediate frequency f _Г2 -f _Г3 = 2f _пр and are chosen symmetrical with respect to the carrier frequency f _{2 of the} main receiving channel f ₂ -f _Г3 = f _Г2 -f ₂ = f _pr2 .

This circumstance leads to a doubling of the number of additional receiving channels, but creates favorable conditions for their suppression due to the correlation processing of channel voltages.

At the output of the mixers 13 and 24, voltages of combination frequencies are generated. Amplifiers 14 and 25 are allocated voltage of the second intermediate (differential) frequency

;Where

;

;

;

f _CR2 = f _U2 -f ₂ = f ₂ -f _G3 - the second intermediate (difference) frequency;

ϕ _CR2 = ϕ _G2 -ϕ ₂ ,

ϕ _pr3 = ϕ ₂ -ϕ _G3 .

The _voltages u _CR2 (t) and u _CR3 (t) are supplied to the two inputs of the second correlator 26, at the output of which a voltage U (τ) is generated proportional to the correlation function R (τ), which is compared with the threshold voltage U _then in the threshold block 27. The threshold level U _{then is} exceeded only at the maximum voltage U _max (τ). Since the channel voltages u _pr2 (t) and u _pr3 (t) are formed by the same noise-like signal u ₂ (t) received on two channels at the same frequency f ₂ , there is a strong correlation between these channel voltages . In addition, the correlation function R (τ) of noise-like signals has a pronounced main lobe and a relatively low level of side lobes. Therefore, the maximum voltage U _max (τ) is formed at the output of the correlator 26, which exceeds the threshold level U _pores in the threshold block 27 [U _max (τ)> U _pores ]. When the threshold level U _pores is exceeded, a voltage is generated in the threshold block 27, which is supplied to the control input of the key 28 and opens it. In the initial state, the key 28 is always closed.

In this case, the relay signal u ₂ (t) (signal α ₂ ) from the output of the first amplifier 14 of the second intermediate frequency through the public key 28 is fed to the input of the clipper 15, where it is clipped, and recorded in the buffer memory 16.

In the second step (when transmitting the signal from point B), the switch 4 must be open and the signal α ₃ from the generator 3 through the clipper 10 enters the same storage device 11.

,

.The relay signal α _{4 is} recorded, like the signal α ₂ , in the memory 16. Then, in the interval between the measurement acts, the pairs of signals α ₁ , α ₂ and α ₃ , α ₄ are subjected to correlation processing in the meter 17 and the delays τ ₂ , τ ₃ are calculated and their derivatives

,

.

The registered probe signal from the output of the memory unit 11 is supplied through the adjustable delay unit 18 to the first input of the multiplier 19, to the second input of which a registered relay signal from the output of the memory unit 16 is supplied. The voltage obtained at the output of the multiplier 19 is passed through a low-pass filter 20, at the output of which a correlation function R (τ) is formed. The extreme controller 21, designed to maintain the maximum value of the correlation function R (τ) and connected to the output of the low-pass filter 20, acts on the control input of the adjustable delay unit 18 and maintains the delay τ introduced by it equal to τ _i (i = 1, 2, 3, 4), which corresponds to the maximum value of the correlation function R (τ). The measurement of the values of τ _i enter the microprocessor 22, where their derivatives are determined.

To ensure symmetry

f ₂ -f _r3 = f _r2 -f ₂ = f _np2,

a phase locked loop (PLL) is used, consisting of a multiplier 29, narrow-band filters 31 and 32, a phase doubler 30, a phase detector 33, and an inverse amplifier 34.

Voltages u _Г2 (t) and u _Г3 (t) from outputs 2.2 and 23 are supplied to two inputs of the multiplier 29, at the output of which a harmonic voltage is generated

Where

f _G2 -f _G3 = 2f _pr2 ,

ϕ _Γ = ϕ _Γ2 -ϕ _Γ3 = 2ϕ _pρ2 ,

which are allocated by the narrow-band filter 31 and is fed to the first input of the phase detector 33.

The voltage u _pr2 (t) from the output of the amplifier 14 of the second intermediate frequency through the open key 28 is fed to the input of the phase doubler 30, at the output of which a harmonic voltage is generated

Where

2f _k (t) = {0, π},

which is allocated by the narrow-band filter 32 and fed to the second input of the phase detector 33.

If this symmetry is violated, a control voltage is generated at the output of the phase detector 33. Moreover, the amplitude and polarity of the control voltage depend on the degree and direction of deviation of the carrier frequency f ₂ from the frequencies f _g3 and f _{g3 of the} second 22 and third 23 local oscillators. The specified voltage through the inverse amplifier 34 acts on the control inputs of the second 22 and third 23 local oscillators so that the symmetry condition is satisfied

f _pr2 = f _U2 -f ₂ = f ₂ -f _G3 .

In point B, the equipment works in a similar way, only the order of steps there is the opposite. To calculate the difference in the clock readings Δt according to formula (2), it is now sufficient to exchange between points obtained by digital data, which can be done using ordinary telephone or telegraph communication channels.

The described operations allow you to:

- achieve extreme measurement accuracy (about ± 0.1 ns) using VLBI technology and relay technology, which is already widely used in practice;

- generate the necessary microwave signals for measurements at ground stations, which makes it possible to gradually increase the accuracy of measurements by optimizing the signal structure and improving the ground-based recording technique without interfering with the satellite onboard equipment;

- increase the efficiency of measurements, i.e. bring the time interval from the beginning of measurements to obtain results up to several tens of seconds (almost to the time of correlation signal processing);

- to avoid the installation of highly stable time keepers and time interval meters onboard the satellite, to limit the on-board equipment only to the system of phase-stable registration of microwave signals.

Known technical solutions provide improved measurement accuracy of the relative time shift between the probing and relayed noise-like signals. This is achieved by automatically tracking the movement of the extremum of the correlation function of these signals along the abscissa.

From the point of view of measurement technology, the proposed correlation extreme system is a compensation measuring system, i.e. in it, the measured value (time interval) is compared with some reference value (time delay). The compensation method allows measurement with very high accuracy. The proposed correlation measuring system provides a methodological measurement error equal to fractions of a percent.

The operation of the device described above corresponds to the case of receiving useful noise-like signals on the main channel at a frequency f ₂ (Fig. 4).

If a false signal (interference) arrives, for example, through the first mirror channel at a frequency f _s1

the amplifiers 14 and 25 of the second intermediate frequency are allocated the following voltages:

Where

f _CR2 = f _G3 -f _Z1 ;

3f _pr2 = f _G2 -f _Z1 ;

ϕ _CR4 = ϕ _G3 -ϕ _Z1 ,

ϕ _pr5 = ϕ _Г2 -ϕ _З1 ;

However, only the voltage u _CR4 (t) falls into the passband of the amplifier 14 of the second intermediate frequency. The output voltage of the correlator 26 is zero, the key 28 does not open, and a false signal (interference) received on the first mirror channel at a frequency f _Z1 is suppressed.

For a similar reason, a false signal (interference) received on the second mirror channel at a frequency f _З2 and on any other additional reception channel is also _suppressed .

If a false signal (interference) is simultaneously received on the first and second mirror channels:

the amplifiers 14 and 25 of the second intermediate frequency are allocated the following voltages:

Where

which enter the two inputs of the correlator 26. But the key 28 in this case does not open. This is because different false signals (interference) u _З1 (t) and u _З2 (t) are received at different frequencies f _З1 and f _З2 , so there is a weak correlation between the channel voltages u _pr4 (t) and u _pr6 (t) communication. In addition, it should be noted that the correlation function of interference does not have a pronounced lobe, as is the case with complex noise-like signals. The output voltage of the correlator U (τ) in this case does not exceed the threshold level of U _pores in the threshold unit 27, the key 28 does not open, and false signals (interference) received simultaneously on two mirror channels at frequencies f _З1 and f _З2 are suppressed.

For a similar reason, false signals (interference) received simultaneously on two other additional channels are suppressed.

Thus, the proposed method and device in comparison with prototypes provide increased noise immunity and accuracy of synchronization of remote time scales. This is achieved by ensuring the symmetry of the frequencies f _G2 and f _{G3 of the} second and third local oscillators relative to the frequency f _{2 of the} main receiving channel

f _pr2 = f _U2 -f ₂ = f ₂ -f _G3 .

The indicated symmetry is performed due to phase automatic tuning of the frequencies f _Γ2 and f _{Г3 of the} local oscillators 22 and 23.

Claims (3)

1. A clock synchronization method based on the simultaneous reception of noise-like microwave signals from an artificial Earth satellite by spaced ground points, their coherent conversion to a video frequency, digital recording of received signals and determining the time delay of the arrival of the same signal to synchronization points by correlation processing of recorded signal, the magnitude of which is made comparison of time scales, with the initial time t ₁ to the first clock item using the code n sequence form a noise-like microwave signal is recorded it at the same point, the conditioned signal is converted to a frequency f _1, increase its power emit the amplified signal in the direction of the artificial satellite of the Earth - a repeater in the same time t _1, the clock of the second paragraph using the same code sequence, the same noise-like microwave signal is generated, recorded at the second point, received on-board equipment of an artificial Earth satellite-signal relay at a frequency f ₁ , re-emitted о to the first and second points at a frequency f ₂ while maintaining phase relationships, at an arbitrary time t ₃ according to the clock of the second point, a noise-like microwave signal is generated and recorded in a similar way, the generated signal is converted to frequency f ₁ , amplified by its power, emitted amplified signal in the direction of the artificial satellite of the Earth relay, the same point of time t ₃ by the clock of the first item by using the same code sequence form the same noise-like microwave signal, it is recorded in the first paragraph, prini ayut onboard equipment artificial satellite repeater signal at frequency f ₁ and re-emit it at first and second points on the f ₂ frequency while preserving phase relationships, the registered probe signal passed through the variable delay unit, multiply it with a registered repeated signals, emit a low-frequency voltage, thereby forming the correlation function R (τ), where τ is the current time delay, by varying the delay τ, the correlation function R (τ) is maintained at the maximum level, f ix the time delay τ _i (i = 1, 2, 3, 4) between two pairs of registered probing and registered signals, the magnitude of which is used to compare time scales, while the received signal at the carrier frequency f _{2 is} converted in frequency using frequencies f _Г2 and f _{Г3 of the} second and third local oscillators, which are doubled by the second intermediate frequency f _Г2 -f _Г3 = 2f _пр2 and are symmetrical with respect to the frequency f _{2 of the} main receiving channel f ₂ -f _Г3 = f _Г2 -f ₂ , the second intermediate voltage frequency f _CR2 = f ₂ -f _G3 and f _CR2 = f _G2 -f ₂ , they are subjected to correlation processing, a voltage U (τ) is generated proportional to the correlation function R (τ), it is compared with a threshold voltage, and if it is exceeded, a voltage is generated that is used to allow further processing of the first voltage second intermediate frequency, characterized in that the voltages of the second and third local oscillators are multiplied among themselves, emit the first narrow-band voltage of twice the second intermediate frequency, double the phase of the first voltage of the second intermediate second frequency, allocate second narrowband voltage twice the second intermediate frequency, comparing the first and second narrowband voltage twice the second intermediate frequency phase, form a control voltage of positive or negative polarity, influence them to control inputs oscillators so as to perform their symmetry with respect to the frequency f ₂ of the main receive channel f _pr2 = f _U2 -f ₂ = f ₂ -f _G3 . 2. A clock synchronization device containing an IS3 repeater, first and second ground stations, each of which contains a time and frequency standard connected in series, a first local oscillator, a first mixer, the second input of which is connected via a switch to the first output of a pseudo-noise signal generator, and an amplifier of the first intermediate frequency, the first power amplifier, a duplexer, the input-output of which is connected to the transceiver antenna, the second power amplifier, the second mixer, the second input of which is connected through the second the oscillator with the first output of the time and frequency standard, and the first amplifier of the second intermediate frequency, the second clipper, the second input of which is connected to the third output of the time and frequency standard, the second memory unit and the first correlator, while the first clipper is connected in series to the second output of the pseudo noise signal generator , the second input of which is connected to the second output of the standard time and frequency, and the first memory block, the output of which is connected to the second input of the first correlator, which is made in the form of series-connected x to the output of the first memory block of the adjustable delay unit, a multiplier, the second input of which is connected to the output of the second memory unit, a low-pass filter and an extreme controller, the output of which is connected to the second input of the adjustable delay unit, the microprocessor is connected to the second output to the output of the second amplifier a third mixer, the second input of which is connected to the output of the third local oscillator, the second amplifier of the second intermediate frequency, the second correlator, the second input of which connected to the output of the first amplifier of the second intermediate frequency threshold unit and the key, a second input coupled to an output of the first amplifier of the second intermediate frequency, and an output connected to the first input of the second clipper, frequency f _T2 and f _T3 second and third oscillators are spaced by twice the value of the second intermediate frequency f _Г2 -f _Г3 = 2f _пр2 and selected symmetrical with respect to the frequency f _{2 of the} main receiving channel f ₂ -f _Г3 = f _Г2 -f ₂ = f _pr2 , characterized in that it is equipped with a second multiplier, two narrow-band filters, double phase, phase detector and inverse amplifier, and the second multiplier is connected in series to the output of the second local oscillator, the second input of which is connected to the output of the third local oscillator, the first narrow-phase detector and inverse amplifier, and the second multiplier, the second input of which is connected to the output of the second local oscillator the output of the third local oscillator, the first narrow-band filter, a phase detector and an inverse amplifier, the first and second outputs of which are connected to the control inputs of the second and third local oscillators, respectively, to the output of the key successively connected phase doubler and a second narrow band filter, whose output is connected to a second input of the phase detector.

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