RU2619094C1 - Method of clock synchronization and device for its implementation - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device for the clock synchronization realizing the proposed method, comprises a standard 1 of frequency and time, local oscillators 2.1, 2.2, a dither signal generator 3, a switch 4, mixers 5, 13, 19, 28 and 30, an amplifier of the first intermediate frequency, and power amplifiers7 and 12, a duplexer 8, a transceiving antenna 9, clippers 10 and 15, buffer memories 11 and 16, amplifiers 14 and 20 of the second intermediate frequency, a meter 17 of the delays and their derivatives, phase shifters 18 and 21 at 90°, adders 22, 41, 44 and 48, multipliers 23 and 34, narrow-band filters 24 and 39, an amplitude detector 25, a key 26, a reference frequency block 27, an amplifier 29 of the third intermediate frequency, low frequency filters 31 and 35, a meter 32 of Doppler frequencies, a correlator 33, an extreme knob 36, a variable delay block 37, a range indicator 38, phase inverters 40, 43 and 46.

EFFECT: increasing the noise immunity and the synchronization accuracy of the remote time scales by suppressing false signals received on the direct transmission channel and on the intermodulation channels.

2 cl, 6 dwg

Description

The proposed method and device relate to communication technology and can be used in radio interferometry with extra-long bases (VLBI), as well as in the time and frequency service.

Known methods and devices for clock synchronization (ed. Certificate of the USSR No. 591.799, 614.416, 970.300, 1180.835, 1.244.631, 1.278.800; RF patents No. 2000.00043, 2.003.157, 2.040.035, 2.146.833, 2.177.167, 2.392.574, 2.386.159, 2.439.643, 2.535.653; German patent No. 3.278.943; EP patent No. 0.564.289 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. 2.535.653, 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 method of communication through a geostationary satellite repeater.

The known method and device provide suppression of false signals (interference) received on the mirror and Raman channels.

However, in addition to these, there are other additional (direct channel and intermodulation channels) receiving channels.

If the interference frequency ω _p is equal to or close to the second intermediate frequency ω _CR2 (ω _p = ω _CR2 ), then a direct channel is formed.

If two or more powerful signals at frequencies ω _I and ω _II appear in the frequency band Δω _p1 located “to the left” of the passband Δω _{p of the} receiver, then when they interact on nonlinear elements, intermodulation components form, some of which fall into the band transmitting Δω _{p of the} receiver as intermodulation interference (Fig. 5).

If two or more powerful signals at frequencies ω _III and ω _IV appear in the frequency band Δω _p2 located “to the right” of the passband Δω _{p of the} receiver, then when they interact on nonlinear elements, intermodulation components form, some of which fall into the band transmitting Δω _{p of the} receiver as intermodulation interference (Fig. 6).

The presence of false signals (interference) received through the direct channel and intermodulation channels leads to a decrease in noise immunity and accuracy of synchronization of remote time scales.

An object of the invention is to increase the noise immunity and accuracy of synchronization of remote time scales by suppressing false signals (interference) received on the direct channel and on intermodulation channels.

The problem is solved in that the clock synchronization method, based, in accordance with the closest analogue, on the simultaneous reception by separated points of noise-like microwave signals from the artificial Earth satellite, coherently converting them to a video frequency, digitally recording the received signals and determining the time delay of arrival of one and of the same signal to synchronization points by the method of correlation processing of registered signals, the magnitude of which is used to compare time scales, while in the initial time t ₁ according to the clock of the first point using a code sequence form a noise-like microwave signal, register it at the same point, the generated signal is converted to a frequency ω ₁ , amplify it by power, emit an amplified signal in the direction of an artificial Earth repeater satellite, at 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 artificial satellite and relay Earth signal at frequency ω _1, re-emit it at first and second points at the frequency ω ₂ while preserving phase relationships, at an arbitrary time t ₃ by the clock of the second paragraph similarly formed and retransmit noise-like microwave signal generated signal is converted to the frequency ω ₁ , 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, reg it is abraded at the first point, the signal at the frequency ω _{1 is} received by the onboard equipment of the satellite repeater and re-emitted to the first and second points at the frequency ω ₂ while maintaining phase relationships, the received signal at the frequency ω _{2 is} converted in frequency using the voltage of the second local oscillator shifted in phase by + 90 °, the voltage of the second intermediate frequency is isolated, it is shifted in phase by -90 °, summed with the initial voltage of the second intermediate frequency, the resulting total voltage is multiplied with the received signal, output they produce a harmonic voltage at a frequency ω _{g2 of the} second local oscillator, detect it and use it to further process the received signal, differs from the closest analogue in that the resulting total voltage is converted in frequency using the voltage of the first reference frequency ω _E1 , the voltage of the third intermediate frequency is isolated

ω _pr3 = ω _pr2 + Ω _{D -ω E1} ,

convert it in frequency using the voltage of the second reference frequency

ω _E2 = ω _{pr2 -ω} E1 -Ω ₀ ,

where Ω ₀ is the frequency of the stand, which is introduced to determine the sign of the Doppler shift Ω _D ,

emit low frequency voltage

ω _N = Ω _D + Ω ₀ ,

measure the low frequency ω _Н and depending on whether ω _Н > Ω ₀ or ω _Н <Ω ₀ , determine the sign of the Doppler shift, and consequently, the direction of the radial velocity of the satellite repeater, at the same time the resulting voltage is multiplied with a noise-like microwave signal missed through the adjustable delay unit, a low-frequency voltage is proportional to the correlation function R (τ), where τ is the current time delay, the time delay τ is changed until the equality τ = τ _{З is} obtained, which corresponds to the maximum value of the correlation ionic function R (τ), support it and determine the distance from a ground station to an AES repeater according to the formula

,

,

where c is the propagation speed of radio waves, differs from the closest analogue in that if a false signal (interference) enters the direct channel at a frequency ω _p equal to the second intermediate frequency ω _pr2 (ω _p = ω _pr2 ), then it is isolated by a narrow-band filter, the tuning frequency ω _{N of} which is chosen equal to the second intermediate frequency ω _AC2 (ω _N = ω _AC2 ), is inverted by 180 ° in phase and summed with the original signal, compensating for it by the phase-compensation method, if two or more powerful signals fall into the frequency band Δω _p1 , located Eva "from the passband Δω _{p of the} receiver, and the interaction of which on nonlinear elements leads to the formation of intermodulation components, some of which fall into the passband Δω _{p of the} receiver as intermodulation interference, then select these signals with a band-pass filter, the tuning frequency ω _n2 and the starting Δω _p1 which is selected as follows:

,

,

where ω _I and ω _II are the boundary frequencies;

they are inverted in phase by 180 ° and summed with the original signals, compensated by their phase-compensation method, if two or more powerful signals fall into the frequency band Δω _p2 located "to the right" of the passband Δω _{p of the} receiver, and the interaction of which on non-linear elements leads to formation of intermodulation products, some of which fall within the bandwidth Δω _n receiver as intermodulation noise, then the narrowband signals isolated by a bandpass filter frequency ω _2n settings and bandwidth Δω _n2 is selected as follows:

, Δω_п2=ω_IV-ω_III,

, Δω _n2 = ω _IV -ω _III ,

where ω _IV and -ω _III are the boundary frequencies,

they are inverted in phase by 180 ° and summed with the original signals, compensating for their phase-compensation method.

The problem is solved in that a clock synchronization device containing a geostationary satellite repeater, first and second ground stations, each of which contains a frequency and time standard, a first local oscillator, a first mixer, the second input of which is connected via a switch to the first output of the generator a pseudo-random signal, a first intermediate frequency amplifier, a first power amplifier, a duplexer whose input-output is connected to a transceiver antenna, and a second power amplifier, p consequently included a second mixer, the second input of which is connected through the second local oscillator to the first output of the frequency and time standard, the first amplifier of the second intermediate frequency, the first adder, the first multiplier, the first narrow-band filter, the amplitude detector, the key, the second input of which is connected to the output of the first adder, a second clipper, the second input of which is connected to the second output of the frequency and time standard, a second buffer storage device and a meter of delays and their derivatives, the output of which is the output of a ground station, a pseudo-random signal generator, a first clipper, the second input of which is connected to the second output of the frequency and time standard, and a first buffer storage device, the output of which is connected to the second input of the delay meter and their derivatives, connected in series to the third output of the frequency and time standard, the first phase shifter 90 °, the third mixer, the second amplifier of the second intermediate frequency and the second phase shifter 90 ° connected in series to the output of the second local oscillator, the output to which is connected to the second input of the first adder, and the fourth mixer is connected in series to the key, the second input of which is connected to the first output of the reference frequency unit, the amplifier of the third intermediate frequency, the fifth mixer, the second input of which is connected to the second output of the reference frequency unit, the first low-pass filter frequencies and a Doppler frequency meter, a second multiplier, a second low-pass filter, an extreme regulator and an adjustable delay unit, are secondly connected to the key output the path of which is connected to the output of the pseudo-random signal generator, the first output is connected to the second input of the second multiplier, and the second output is connected to the range indicator, differs from the closest analogue in that it is equipped with a second narrow-band filter, three inverters, a second, third and fourth adders and two band-pass filters, and the second narrow-band filter, the first phase inverter, the second adder, the second input of which is connected to the output of the second power amplifier, a first bandpass filter, a second phase inverter, a third adder, the second input of which is connected to the output of the second adder, a second bandpass filter, a third inverter and a fourth adder, the second input of which is connected to the output of the third adder, and the output is connected to the second inputs of the first multiplier, second and third mixers.

The geometric arrangement of points A, B and the satellite relay S is shown in FIG. 1, where the following notation is introduced: O is the center of mass of the Earth; d is the base of the interferometer; r is the radius vector of the satellite repeater. The timing diagram of the duplex clock comparison method is shown in FIG. 2, where the following notation is introduced: S, A, B are the time scales of the satellite repeater, ground points A and B, respectively. The structural diagram of the equipment of one of the ground points (A) that implements the proposed method for clock synchronization is shown in FIG. 3. A frequency diagram illustrating signal conversion is shown in FIG. 4, 5 and 6.

The device for clock synchronization contains serially connected frequency and time standard 1, a first local oscillator 2.1, a first mixer 5, a second input of which is connected via a switch 4 to a first output of a pseudo-random signal generator, an amplifier 6 of a first intermediate frequency, a first power amplifier 7, a duplexer 8, an input - the output of which is connected to the transceiver antenna 9, a second power amplifier 12, a second narrow-band filter 39, a first phase inverter 40, a second adder 41, the second input of which is connected to the output of the second amplifier For power 12, the first bandpass filter 42, the second phase inverter 43, the third adder 44, the second input of which is connected to the output of the second adder 41, the second bandpass filter 45, the third phase inverter 46 and the fourth adder 47, the second input of which is connected to the output of the third adder 44, the second mixer 13, the second input of which is connected through the second local oscillator 2.2 to the first output of frequency and time standard 1, the first amplifier 14 of the second intermediate frequency, the first adder 22, the first multiplier 23, the second input of which is connected to the output of the fourth an adder 42, a narrow-band filter 24, an amplitude detector 25, a key 26, the second input of which is connected to the output of the first adder 22, a second clipper 15, the second input of which is connected to the second output of the frequency and time standard 1, a second buffer memory 16 and a delay meter 17 and their derivatives, the output of which is the output of the equipment of a ground station.

A pseudo-random signal generator 3 is connected to the third output of the frequency and time standard 1, the first clipper 10, the second input of which is connected to the second output of the frequency and time standard 1, and the first buffer memory 11, the output of which is connected to the second input of the delay meter 17 and their derivatives. The output of the second local oscillator 2.2 is connected in series to the first phase shifter 18 by 90 °, the third mixer 19, the second input of which is connected to the output of the fourth adder 47, the second amplifier 20 of the second intermediate frequency and the second phase shifter 21 by -90 °, the output of which is connected to the second input of the adder 22. The fourth mixer 28, the second input of which is connected to the first output of the reference frequency unit 27, the amplifier 29 of the third intermediate frequency, the fifth mixer 30, the second input of which is connected to the second The direct output of the block 27 reference frequencies, the first low-pass filter 31 and the meter 32 Doppler frequency. A second multiplier 34, a second low-pass filter 35, an extremal regulator 36, and an adjustable delay unit 37 are serially connected to the output of the key 26, the second input of which is connected to the output of the pseudo-random signal generator 3, the first output is connected to the second input of the second multiplier 34, and the second output is connected to the indicator 38 range.

The second multiplier 34, the second lower filter 35 often, the extreme controller 36 and the adjustable delay unit 37 form a correlator 33.

Clock synchronization by the proposed method is as follows. At time t ₁ ^A, according to the clock of the first point A, a noise-like microwave signal is generated using a code sequence (signal α ₁ ) (Fig. 2):

u _c (t) = U _with cos [ω _c t + ϕ _k (t) + ϕ _s ], 0≤t≤T _s ,

where U _s , ω _s , ϕ _s , T _s - amplitude, carrier frequency, initial phase and signal duration;

φ _k (t) = {0, π} - manipulated component phase mapping law phase shift keying in accordance with the code sequence M (t), wherein φ _k (t) = const at kτ _E <t <(k + 1) τ _Oe and can change abruptly at t = kτ _Oe , i.e. at the boundaries between elementary premises (K = 1, 2, ... N-1);

τ _E , N - the duration and number of chips that make up a signal of duration T _s (T _s = Nτ _E ),

in generator 3 using standard 1 frequency and time.

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

The generated signal u _c (t) 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

u _Г1 (t) = U _Г1 cos (ω _Г1 t + ϕ _Г1 ).

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

u _CR1 (t) = U _CR1 cos [ω _CR1 + ϕ _k (t) + ϕ _CR1 ], 0≤t≤T _c ,

;Where

;

To ₁ - gear ratio of the mixer;

ω _CR1 = ω _s + ω _G1 - the first intermediate (total) frequency;

ϕ _pr1 = ϕ _with + ϕ _G1 ,

which, after amplification in the power amplifier 7, through the duplexer 8 and the transceiver antenna 9 is radiated in the direction of the satellite repeater at a frequency of ω ₁ = ω _pr1 .

At the same time t ₁ ^A = t ₁ ^B according to 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 point B (signal β ₁ , which, however, is not sent for relay). Accept on-board equipment of the satellite repeater at a frequency of ω ₁ (signal α ₁ ), re-emit it to points A and B at a frequency of ω ₂ while maintaining phase relationships in the interval t _c .

Relay signal (signal α ₂ ) at a frequency of ω ₂

u ₂ (t) = U ₂ cos [(ω ₂ ± Ω _Д ) (t-τ _P ) + ϕ _k (t-τ _З ) + ϕ ₂ ], 0≤t≤T _c ,

where ± Ω _D - Doppler frequency shift;

- время запаздывания ретранслированного сигнала относительно запросного;

- the delay time of the relay signal relative to the request;

R is the distance from the ground point to the satellite repeater;

C is the propagation velocity of radio waves,

it is received by the transceiver antenna 9 and through the duplexer 8 and the power amplifier 12 and the adders 41, 44, 47, for which only one arm operates, is fed to the first inputs of the second 13 and third 19 of the mixer and the first multiplier 23. The second inputs of the mixers 13 and 19 are fed voltage of the second local oscillator 2.2:

u _Г2 (t) = U _Г2 cos (ω _Г2 t + ϕ _Г2 ),

u _Г3 (t) = U _Г2 cos (ω _Г2 t + ϕ _Г2 + 90 °).

Moreover, the frequencies ω _G1 and ω _{G2 of the} first 2.1 and second 2.2 local oscillators are spaced by the value of the second intermediate frequency (Fig. 4)

w _{G1 G2} -ω = ω _WP2.

At the output of the mixers 13 and 19, a voltage of combination frequencies is generated. Amplifiers 14 and 20 are allocated voltage of the second intermediate (differential) frequency:

u _CR2 (t) = U _CR2 cos [(ω _CR2 ± Ω _D ) (t-τ _З ) + ϕ _k (t-τ _З ) + ϕ _CR2 ],

u _CR3 (t) = U _CR2 cos [(ω _CR2 ± Ω _D ) (t-τ _З ) + ϕ _k (t-τ _З ) + ϕ _CR2 + 90 °], 0≤t≤T _s ,

;Where

;

To ₁ - gear ratio of the mixer;

ω _CR2 = ω _G2 -ω ₂ - the second intermediate (difference) frequency;

ϕ _pr2 = ϕ _G2 -ϕ ₂ .

The voltage u _pr3 (t) from the output of the amplifier 20 of the second intermediate frequency is supplied to the input of the phase shifter 21 by -90 °, at the output of which a voltage is generated

u _CR4 (t) = U _CR2 cos [(ω _CR2 t ± Ω _D ) (t-τ _З ) + ϕ _k (t-τ _З ) + ϕ _CR2 + 90 ° -90 °] =

= U _CR2 cos [(ω _CR2 t ± Ω _D ) + ϕ _k (t-τ _З ) + ϕ _CR2 ].

The voltage u _pr2 (t) and u _pr4 (t) from the output of the amplifier 14 of the second intermediate frequency and phase shifter 21 by -90 ° are supplied to the two inputs of the adder 22, at the output of which the total voltage

u _Σ (t) = U _Σ cos [(ω _pr2 ± Ω _D ) + ϕ _k (t-τ _З ) + ϕ _pr2 ], 0≤t≤I _s ,

where U _Σ = 2U _pr2 ,

which goes to the second input of the first multiplier 23. At the output of the last, a harmonic voltage is generated

u ₁ (t) = U ₁ cos (ω _U2 t + ϕ _Г2 ), 0≤t≤T _c ,

;Where

;

K ₂ - transfer coefficient of the multiplier,

which is allocated by a narrow-band filter 24 (the tuning frequency ω _{n of} which is chosen equal to the frequency ω _{G2 of the} second local oscillator 2.2 ω _n = ω _G2 ) is detected by the amplitude detector 25 and is fed to the control input of the key 26, opening it. In the initial state, the key 26 is always closed.

In this case, the voltage u _Σ (t) from the output of the adder 22 through the public key 26 is supplied simultaneously to the first input of the second clipper 15, the fourth mixer 28 and the second multiplier 34. In the second clipper 15, the indicated total voltage u _Σ (t) is clipped and then recorded into the second storage device 16. Registration is synchronized by standard 1 frequency and time.

To determine the speed and direction of movement of the satellite repeater relative to the ground point, it is necessary to measure the Doppler frequency shift ± Ω _D. For this, multiple conversion of the frequency of the received signal is used. It is necessary because the relative value of the Doppler shift Ω _D / ω ₂ equal to the ratio of velocities V _R / c, where V _R is the radial component of the velocity of the satellite repeater, c is the propagation velocity of the radio waves, does not exceed 10 ^-4 . Under these conditions, the separation of the Doppler shift during a single frequency conversion of the received signal requires the use of circuits with a very high, almost unattainable quality factor.

The total voltage u _Σ (t) from the output of the adder 22 through the public key 26 is supplied to the first input of the fourth mixer 28, the second input of which is supplied with the voltage of the first reference frequency ω _E1 from the first output of the block 27 of the reference frequencies. At the output of the mixer 28, voltages of combination frequencies are generated. The amplifier 29 is allocated the voltage of the third intermediate frequency

ω _pr3 = ω _pr2 + Ω _{D -ω E1} ,

which is fed to the first input of the fifth mixer 30. The second input of the last voltage of the second reference frequency

ω _E2 = ω _{pr2 -ω} E1 -Ω ₀ ,

where Ω _D is the frequency of the stand, which is introduced to determine the sign of the Doppler shift Ω _D. The nominal frequency of the stand is selected from the condition

.

.

At the output of the mixer 30, voltages of combination frequencies are generated. Low-pass filter 31 provides low-frequency voltage

ω _n = Ω _D + Ω ₀ ,

which is fed to the input of the Doppler frequency meter 32, where the Doppler bias measurement Ω _{D is} measured.

Moreover, depending on whether ω _Н > Ω _Д or ω _Н <Ω _Д , they determine the sign of the Doppler shift, and, consequently, the direction of the radial velocity of the satellite repeater.

The total voltage u _Σ (t) is also supplied to the first input of the second multiplier 34, the second input of which from the output of the pseudo-random signal generator 3 is fed a noise-like microwave signal u _c (t) through the adjustable delay unit 37. The voltage obtained at the output of the multiplier 34 is passed through a low-pass filter 35, at the output of which a correlation function R (τ) is formed, where τ is the current time delay. The extreme controller 36, designed to maintain the maximum value of the correlation function R (τ) and connected to the output of the low-pass filter 35, acts on the control input of the adjustable delay unit 37 and maintains the delay τ introduced by it equal to τ _З (τ = τ _З ), which corresponds to the maximum value of the correlation function R (τ). The range indicator 38, associated with the scale of the adjustable delay unit 37, allows you to directly read the measured value of the distance R from the ground point to the satellite repeater according to the formula

,

,

where c is the propagation velocity of radio waves.

Therefore, the task of measuring the distance R from a ground station to an artificial satellite repeater is reduced to automatic measurement of the time delay τ _{3 of the} relay signal relative to the interrogation signal.

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 memory 11. The relay signal α _{4 is} recorded, like α ₂ , in the memory 16.

At an arbitrary point in time t ₃ ^V = t ₂ ^V + Θ, a noise-like microwave signal (β ₃ signal) is similarly generated and recorded by the hours of the second point. The generated signal is converted at a frequency of ω ₁ , amplified by power, emitted amplified signal in the direction of the same satellite repeater.

At the same time t ₃ ^B = t ₃ ^A , the same noise-like microwave signal (signal α ₃ ) is formed using the same code sequence using the same code sequence. Register it at the first point A. Accept the on-board equipment of the satellite relay signal at a frequency of ω ₁ (signal α ₃ ), re-emit it to points A and B at a frequency of ω ₂ while maintaining phase relationships, receive a relay signal at both points, convert it to video frequency, recorded at time t ₄ ^A and t ₄ ^B, respectively (signal 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:

τ ₁ = β ₁ ⊗ β ₂ = t ₂ ^B -t ₁ ^B = a ₁ + b ₁ + (Δ _B ^AND + Δ _B ^P + ΔS) + Δt,

τ ₂ = α ₃ ⊗ α ₄ = t ₄ ^A -t ₃ ^A = a ₃ + b ₂ + (Δ _B ^AND + Δ _A ^P + ΔS) -Δt,

τ ₃ = α ₁ ⊗ α ₂ = t ₂ ^A -t ₁ ^A = a ₁ + a ₂ + (Δ _А ^И + Δ _А ^П + ΔS),

τ ₄ = β ₃ ⊗ β ₄ = t ₄ ^B -t ₃ ^B = b ₂ + b ₃ + (Δ _B ^AND + Δ _B ^P + ΔS)

and the corresponding interference frequencies F _i (i = 1, 2, 3, 4), which determine the derivatives of these delays:

,

,

,Where

,

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

Δ _A ^AND , Δ _B ^AND - signal delays in the radiating equipment of both points;

Δ _A ^P , Δ _B ^P - signal delay in the receiving and recording equipment;

ΔS - signal delay in the onboard satellite repeater;

Δt = t ₁ ^B -t ₁ ^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

,

,

,

,

,

,

,

,

Δ _{A, B '} , Δ _{A, B ”} - signal delay in the atmosphere at frequencies ω ₁ and ω _2, respectively;

ν - relativistic correction (Sagnac effect);

ω is the angular velocity of the Earth;

c is the speed of light;

D is the area of the quadrilateral OA'S'B ', formed in the equatorial plane by the center of mass of the Earth, the projections of points A, B and the satellite S.

Corrections γ on the mobility of the satellite repeater during 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.

At point B, the equipment works similarly, only the order of steps there is the opposite. To calculate the difference between the clock readings Δt, it is now sufficient to exchange the received digital data between the points, which can be done via ordinary telephone or telegraph communication channels.

The above operation of the device that implements the proposed method, corresponds to the reception of useful signals on the main channel at a frequency of ω ₂ (Fig. 4).

If a false signal (interference)

u _З (t) = U _З cos (ω _З t + ϕ _З ), 0≤t≤T _З

is taken through the mirror channel at a frequency of ω _З , then the following voltages are allocated by amplifiers 14 and 20 of the second intermediate frequency:

u _CR5 (t) = U _CR5 cos (ω _CR2 t + ϕ _CR5 ),

u _CR6 (t) = U _CR5 cos (ω _CR2 t + ϕ _CR5 -90 °), 0≤t≤T _З ,

;Where

;

To ₁ is the gain of the amplifier;

ω _CR2 = ω _G -ω _G2 - the second intermediate (difference) frequency;

ϕ _pr5 = ϕ ₃ -ϕ _G2 .

The voltage u _pr6 (t) from the output of the amplifier 20 of the second intermediate frequency is supplied to the input of the phase shifter 21 by -90 °, at the output of which the following voltage is generated:

u _CR7 (t) = U _CR5 cos (ω _CR2 t + ϕ _CR5 -90 ° -90 °) = - _{CR CR5} (ω _CR2 t + ϕ _CR5 ), 0≤t≤T _P.

The _voltages u _CR5 (t) and u _CR7 (t) supplied to the two inputs of the adder 22 are compensated at its output.

Therefore, a false signal (interference) received on the mirror channel at a frequency of ω ₃ is suppressed.

For a similar reason, a false signal (interference) received on the second combination channel at a frequency of ω _{k2 is also} suppressed.

If a false signal (interference) is received on the first combinational channel at a frequency ω _k1

u _K1 (t) = U _K1 cos (ω _K1 t + ϕ _K1 ), 0≤t≤T _K1 ,

the amplifiers 14 and 20 of the second intermediate frequency are allocated the following voltages:

u _CR8 (t) = U _CR2 cos (ω _CR2 t + ϕ _CR8 ),

u _PR9 (t) = U _CR8 cos (ω _CR2 t + ϕ _CR8 + 90 °), 0≤t≤T _K1 ,

;Where

;

ω _CR2 = 2ω _G2 -ω _K1 - the second intermediate (difference) frequency;

ϕ _pr8 = ϕ _G2 -ϕ _K1 .

The voltage u _pr9 (t) from the output of the amplifier 20 of the second intermediate frequency is supplied to the input of the phase shifter 21 by -90 °, at the output of which a voltage is generated:

u _pr10 (t) = U _pr8 cos (ω _pr2 t + ϕ _pr8 + 90 ° -90 °) = U _pr8 cos (ω _pr2 t + ϕ _pr8 ), 0≤t≤T _K1 .

Voltages u _pr8 (t) and u _pr10 (t) are supplied to two inputs of the adder 22, the output of which forms the following total voltage:

u _Σ1 (t) = U _Σ1 cos (ω _CR2 t + ϕ _CR8 ), 0≤t≤T _K1 ,

where U _Σ1 = 2U _pr8 .

This voltage is supplied to the second input of the multiplier 23, the output of which produces the following harmonic voltage:

u ₂ (t) = U ₂ cos (2ω _Г2 t + ϕ _Г2 ), 0≤t≤T _K1 ,

.Where

.

This voltage does not fall into the passband of the narrow-band filter 24. Therefore, a false signal (interference) received on the first combinational channel at a frequency ω _K1 is suppressed.

If a false signal (interference) enters the direct channel

u _p (t) = U _p cos (ω _p t + ϕ _p ), 0≤t≤T _p ,

where ω _p = ω _CR2 ,

then it enters the first input of the second adder 41, is allocated by a narrow-band filter 39, the tuning frequency ω _{н1 of} which is equal to the second intermediate frequency ω _pr2 (ω _n1 = ω _pr2, ), is inverted in phase to 180 ° phase inverter 40

u _p1 (t) = U _p cos (ω _p t + ϕ _g ), 0≤t≤T _p

and enters the second input of the adder 41, the output of which it compensates.

Therefore, a false signal (interference) received through the direct passage channel at a frequency ω _p = ω _pr2 is suppressed by a filter plug consisting of a narrow-band filter 39, a phase inverter 40, an adder 41, and implementing a phase compensation method.

If two or more powerful signals at frequencies ω _I and ω _II fall into the frequency band Δω _p located "to the left" of the passband Δω _{p of the} receiver, then their interaction on nonlinear elements ensures the formation of intermodulation components, some of which fall into the passband Δω _n receiver as intermodulation interference. The indicated intermodulation interference arrives at the first input of the adder 44, is allocated by a band-pass filter 42, the tuning frequency ω _n2 and the passband Δω _p1 which are selected as follows:

,

,

where ω _I and ω _II are the boundary frequencies,

forming the frequency band Δω _p1 , hit in which two or more powerful signals leads to the formation of intermodulation interference.

These interference are phase inverted by 180 ° in the phase inverter 43 and fed to the second input of the adder 44, where they are compensated.

Consequently, false signals (interference) are received in the frequency band Δω _p1 , located "to the left" of the passband Δω _{p of the} receiver, and leading to the formation of intermodulation interference, are suppressed by the filter plug, consisting of a bandpass filter 42, a phase inverter 43, an adder 44 and realizing phase compensation method.

If two or more powerful signals fall into the frequency band Δω _p2 located “to the right” of the passband Δω _{p of the} receiver, then their interaction on nonlinear elements ensures the formation of intermodulation components, some of which fall into the passband Δω _p as intermodulation interference. The indicated intermodulation interference arrives at the first input of the adder 47, is allocated by a band-pass filter 45, the tuning frequency ω _n3 and the passband Δω _{p2 of} which are selected as follows:

,

,

where ω _III and ω _IV are the boundary frequencies,

forming the frequency band Δω _p2 , hit in which two or more powerful signals leads to the formation of intermodulation interference.

These interference are phase inverted by 180 ° in the phase inverter 46 and fed to the second input of the adder 47, where they are compensated.

Consequently, false signals (interference) received in the frequency band Δω _p2 located "to the right" of the passband Δω _{p of the} receiver and leading to the formation of intermodulation interference are suppressed by the filter plug, consisting of a bandpass filter 45, a phase inverter 46, an adder 47 and realizing phase compensation method.

The clock synchronization method allows you to:

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

- to form the microwave signals necessary for the measurement at ground points, 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 on board of a satellite of highly stable time-keepers and time interval meters, to limit the on-board equipment to only a phase-stable microwave signal relay system.

The proposed method provides improved noise immunity and accuracy of synchronization of remote time scales. This is achieved by suppressing false signals (interference) received via mirror and Raman channels.

Moreover, the suppression of false signals (interference) received via the mirror and the second Raman channel is provided by the phase-compensation method, which is implemented by the local oscillator 2.2, mixers 13 and 19, amplifiers 14 and 20 of the second intermediate frequency, phase shifters 18 and 21 by + 90 ° and -90 ° and adder 22.

The suppression of false signals (interference) received via the first combinational channel is provided by the narrow-band filtering method, which is implemented by a multiplier 23, a narrow-band filter 24, an amplitude detector 25, and a key 26.

The proposed method and device provide improved accuracy of synchronization of remote time scales. This is achieved by measuring the distance R from the ground point to the satellite, the speed and direction of its movement in a geostationary orbit relative to the ground point.

Moreover, the measurement of the radial velocity of the satellite repeater is carried out using multiple frequency conversion of the received signal, is characterized by comparative simplicity and does not have restrictions on the number of ground stations that measure the radial speed of the satellite repeater.

The measurement of the distance R from the ground point to the satellite repeater is carried out automatically using the remarkable property of the correlation function R (τ) of noise-like microwave signals, which has a significant main lobe and a relatively low level of side lobes.

Thus, the proposed method and device in comparison with the prototype and other technical solutions of a similar purpose provide increased noise immunity and accuracy of synchronization of remote time scales. This is achieved by suppressing spurious signals (interference) received on direct channels and on intermodulation channels. Moreover, the suppression of false signals (interference) received through the indicated channels is provided by filter plugs that implement the phase compensation method.

Claims (16)

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 signals for which the magnitude comparison of time scales produce, while at the initial time t ₁ to the clock of the first item using the code pos edovatelnosti form a noise-like microwave signal is recorded it at the same point, the conditioned signal is converted to a frequency ω _1, increase its power, study the amplified signal in the direction of artificial Earth relay satellite 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, the signal at the frequency ω _{1 is} received by the onboard equipment of the artificial Earth-relay satellite, and re-emitted to the first and second points at a frequency of ω 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 a frequency of ω ₁ , amplified by power, emitted amplified signal in the direction of the same artificial satellite repeater Earth at the same time point t _3, the first item on the clock by using the same code sequence form the same noise-like microwave signal, it is recorded in the first paragraph, the received dissolved onboard equipment Earth relay artificial satellite signal at frequency ω ₁ and re-emit it at first and second points at the frequency ω ₂ while preserving phase relationships, the received signal at the frequency ω ₂ is converted in frequency using the voltage of the second local oscillator shifted in phase by + 90 °, the voltage of the second intermediate frequency is isolated, it is shifted in phase by -90 °, summed with the initial voltage of the second intermediate frequency, the resulting total voltage is multiplied with the received signal, the harmonic is isolated voltage at a frequency ω _{G2 of the} second local oscillator, it is detected and used to resolve further processing of the received signal, characterized in that the resulting total voltage is converted in frequency using the voltage of the first reference frequency ω _E1 , the voltage of the third intermediate frequency is isolated

, convert it in frequency using the voltage of the second reference frequency

, where Ω ₀ is the frequency of the stand, which is introduced to determine the sign of the Doppler shift Ω _D , isolate the low frequency voltage ω _Н = Ω _Д + Ω ₀ , measure the low frequency ω _Н and depending on whether ω _Н > Ω ₀ or ω _Н <Ω ₀ , determine the sign of the Doppler shift, and therefore the direction of the radial velocity of the satellite repeater simultaneously obtained total voltage multiplied with the noise-like microwave signal passed through the regulated delay block, allocate a low-frequency voltage proportional to the correlation function R (τ), where τ - current time delay, changing a time delay τ to obtain equality τ = τ _e, h It corresponds to the maximum value of the correlation function R (τ), and determining its supporting distance from ground station to satellite repeater by the formula

, where c is the propagation velocity of radio waves, characterized in that if the signal (interference) enters the direct channel at a frequency ω _p equal to the second intermediate frequency ω _CR2 (ω _p = ω _CR2 ), then it is isolated by a narrow-band filter, the tuning frequency ω _{n of} which is chosen equal to the second intermediate frequency ( ω _n = ω _CR2 ), phase inverse by 180 ° and summed with the original signal, compensating for it by the phase compensation method, if two or more powerful signals fall into the frequency band Δω _CR1 , located "to the left" of the passband Δω _{n of the} receiver, and the interaction which on nonline ynyh elements leads to the formation of intermodulation products, some of which fall within the transmission band Δω _n receiver as intermodulation interference, the said signals is isolated by a bandpass filter, the frequency setting and band ω _2n Δω transmittance _etc. of which are selected as follows:

,

, where ω _I and ω _II are the boundary frequencies, they are inverted in phase by 180 ° and summed with the original signals, compensating for them by the phase-compensation method if two or more powerful signals fall into the frequency band Δω _p2 located "to the right" of the passband Δω _{p of the} receiver, and the interaction of which on nonlinear elements leads to formation of intermodulation products, some of which fall within the transmission band Δω _n receiver as intermodulation interference, the said signals is isolated by a bandpass filter, ω _H3 tuning frequency and the transmission bandwidth Δω ₂ is selected as follows:

,

, where ω _III and ω _IV are the boundary frequencies, invert them by phase by 180 ° and summarize with the original signals, compensate them by phase-compensation method. 2. A device for clock synchronization, containing a geostationary satellite repeater, first and second ground stations, each of which contains a frequency and time standard, a first local oscillator, a first mixer, the second input of which is connected via a switch to the first output of the pseudo-random signal generator, an amplifier the first intermediate frequency, the first power amplifier, a duplexer, the input-output of which is connected to the transceiver antenna, and the second power amplifier, sequentially connected to the second cm carrier is the second input through the second local oscillator connected to the first output of the frequency and time standard, the first amplifier of the second intermediate frequency, the first adder, the first multiplier, the first narrow-band filter, the amplitude detector, the key whose input is connected to the output of the first adder, the second clipper, the second input which is connected to the second output of the frequency and time standard, the second buffer storage device and a meter of delays and their derivatives, the output of which is the output of a ground station, in series connected to the third output of the frequency and time standard of the pseudo-random signal generator, the first clipper, the second input of which is connected to the second output of the frequency and time standard, and the first buffer storage device, the output of which is connected to the second input of the delay meter and their derivatives, connected in series to the output of the second local oscillator, the first phase shifter 90 °, the third mixer, the second amplifier of the second intermediate frequency and the second phase shifter -90 °, the output of which is connected to the second input of the first an adder, and a fourth mixer, the second input of which is connected to the first output of the reference frequency block, an amplifier of the third intermediate frequency, the fifth mixer of which the second input is connected to the second output of the reference frequency block, the first low-pass filter and the Doppler frequency meter, is connected in series to the key output is connected in series with a second multiplier, a second low-pass filter, an extreme regulator and an adjustable delay unit, the second input of which is connected to the generator output pseudo-random signal generator, the first output is connected to the second input of the second multiplier, and the second output is connected to the range indicator, characterized in that it is equipped with a second narrow-band filter, three phase inverters, a second, third and fourth adders and two bandpass filters, and to the output of the second amplifier a second narrow-band filter, a first phase inverter, an adder, a second input of which is connected to the output of a second power amplifier, a first band-pass filter, a second phase inverter, are connected in series Torr, a third adder, a second input coupled to an output of the second adder, a second bandpass filter, the third phase inverter and a fourth adder, the second input of which is connected to the output of the third adder and an output connected to second inputs of the first multiplier, the second and third mixers.

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