RU2623718C1 - Time transmission signals modem through the satellite communication duplex channel - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: modem can be used in the very long baseline radio interferometry (VLBI), in the single time and frequency service, as well as for the information exchange between the ground stations, spaced into the long distances, using the geostationary ESV-repeater. The modem contains the geostationary ESV-repeater, the first A and the second B ground stations, each of which contains the reference 1 of time and frequency, the heterodynes 2 and 3, the transmitting-receiving antenna 4, the duplexer 5, the power amplifiers 6 and 16, the mixers 7 and 14, the amplifier of the first intermediate frequency 8, the clippers 9 and 17, the memory units 10 and 18, the correlators 11 and 24, the pseudonoise signal generator 12, the switch 13, the amplifier 15 of the second intermediate frequency, frequency selector 19, the narrowband filter 20, the amplitude detector 21, the threshold unit 22, the key 23, the adjustable delay unit 25, the remultiplier 26, the lowpass filter 27, the extreme regulator 28 and the range indicator 29. The geostationary ESV-repeater 30 includes a transmitting-receiving antenna 31, the duplexer 32, the power amplifiers 33 and 40, the heterodyne 34, the mixer 35, the third intermediate frequency amplifier 36, the total frequency amplifier 37, the amplitude detector 38 and the key 39.

EFFECT: increase of the noise immunity and reliability of the time transmission through the duplex satellite communication channel by suppression of the false signals, received via additional channels, and automatic measurement of the inclined range up to the geostationary ESV-repeater in order to monitor its position in the orbit.

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Description

The proposed modem relates to communication technology and can be used in radio interferometry with ultra-long bases (VLBI), in the service of a single time and frequency, for the exchange of information between ground points, spaced over long distances, using a geostationary satellite repeater.

Known modems and devices for clock synchronization and comparison of time scales (ed. Certificate of the USSR No. 591799, 614416, 920300, 1120835, 1244637, 1278800, 1840365, 1840516; RF patents No. 2001423, 2403157, 2040035, 2177167, 2292574, 2386159, 2426167, 2528405, 2535653; US patent No. 56666330, 7327699, 8145247; German patent No. 3278943; UK patent No. 1526467; patent EP No. 0564220 and others).

Of the known devices, the closest to the proposed one is “Clock synchronization device” (RF patent No. 20041423, G04C 11/02, 1992), which is chosen as the base object.

The specified device provides a comparison of time scales spaced over long distances, and is based on the use of the duplex method of communication through a geostationary satellite repeater. The main advantage of the duplex communication method is that the signal path length is eliminated. Therefore, its accuracy mainly depends on the parameters of the repeater, the type of signal used, and the technique for measuring time intervals.

In the receiver of a known modem constructed according to a superheterodyne circuit, the same value of the first intermediate frequency ω _pr1 can be obtained by receiving signals at two frequencies ω ₂ and ω _з1 , i.e.

_pr1 ω = ω _d1 and ω ₂ -ω _pr1 = ω _P1 -ω _r1.

Therefore, if the tuning frequency co _{2 is} taken as the main receiving channel, then along with it there will be a first mirror receiving channel, the frequency ω _{s1 of} which differs from the frequency ω ₂ by 2ω _pr1 and is located symmetrically (mirror) with respect to the frequency ω _{g1 of the} first local oscillator 2 (Fig. 5).

The conversion of the first mirror receiving channel occurs with the same conversion coefficient K _ol as the main receiving channel at a frequency of ω ₂ . Therefore, it most significantly affects the selectivity and noise immunity of the receiver.

In addition to the mirror, there are other additional (combinational) reception channels. In general terms, any Raman receive channel occurs when the condition

where ω _кi is the frequency of the i-th Raman reception channel.

The most harmful combinational reception channels are those generated by the interaction of the first harmonic of the signal frequency with the frequency harmonics of the first small local oscillator (second, third), since the sensitivity of the receiver through these channels is close to the sensitivity of the main reception channel. So, two combination channels with n = 1 and n = 2 correspond to frequencies:

ω _k1 = 2ω _{g1 -ω pr1} , ω _k2 = 2ω _g1 + ω _pr1 ,

where 2ω _g1 is the second harmonic of the frequency of the first local oscillator,

The presence of false signals (interference) received via the first mirror channel at a frequency of ω _s1 , along the first ω _k1 and second ω _k2 combination channels, lead to a decrease in noise immunity and reliability of time transmission via a satellite duplex channel.

In addition, the position of the geostationary AES repeater in orbit is not constant, it periodically makes certain movements and monitoring its position in orbit also affects the noise immunity and reliability of time transmission via a duplex satellite communication channel.

An object of the invention is to increase the noise immunity and reliability of time transmission via a duplex satellite communication channel by suppressing false signals (interference) received via additional channels and automatically measuring the slant range to a geostationary satellite repeater in order to control its position in orbit.

The problem is solved in that the modem of the signals for transmitting time via a duplex satellite communication channel, containing, in accordance with the closest analogue, a geostationary satellite repeater, first and second ground stations, each of which contains a time and frequency reference connected in series, a second local oscillator, and a second a mixer, the second input of which is connected via a switch to the first input of the pseudo-noise signal generator, a second intermediate frequency amplifier, a second power amplifier, a first duplexer, the one output of which is connected to the first transceiver antenna, the first power amplifier, the first mixer, the second input of which is connected through the first local oscillator to the first output of the time and frequency standard, and the amplifier of the first intermediate frequency, connected in series to the second output of the time and frequency standard, a pseudo-noise signal generator , 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, the output of which is the signal output of the modem, the first clipper and the first memory block, the output of which is connected to the second input of the first correlator, are connected to the third output of the time and frequency standard, while the frequencies ω _g1 and ω _{g2 of the} first and second local oscillators are spaced by the value of the first intermediate frequency ω _g1 -ω _g2 = ω _PR1 , differs from the closest analogue in that it is equipped with a frequency selector, a narrow-band filter, a first amplitude detector, a threshold block, a first key, a multiplier, an adjustable delay block, a low-pass filter, an extremally adjustable rum and a range indicator, moreover, a frequency selector is connected in series to the output of the first power amplifier, the second input of which is connected to the output of the second local oscillator, a narrow-band filter, the first amplitude detector, a threshold block and the first key, the second input of which is connected to the output of the amplifier of the first intermediate frequency, and the output is connected to the second input of the first clipper, the multiplier is connected in series to the output of the first block, the second input of which is connected through a series-connected switch and control unit my delay is connected to the first output of the pseudo-noise signal generator, a low-pass filter and an extreme regulator, the output of which is connected to the second input of the adjustable delay unit, to the second output of which is connected a range indicator, the geostationary satellite repeater is made in the form of a fourth power amplifier, a second duplexer connected in series the input-output of which is connected to the second transceiver antenna, the third power amplifier, the third mixer, the second input of which is connected to the output of the third the local oscillator, the total frequency amplifier, the second amplitude detector and the second key, the second input of which is connected to the output of the third mixer through the amplifier of the third intermediate frequency and the output is connected to the input of the fourth power amplifier, the modem emits _pseudo-noise signals at the frequency ω ₁ = ω _g1 = ω _pr2 and the received one - to the frequency ω ₂ = ω _r2 = ω _pr2 , where ω _pr2 and ω _pr3 are the second and third intermediate frequencies, respectively, and the geostationary satellite repeater, on the contrary, emits _pseudo - _noise signals at the frequency ω ₂ , and receives - at the frequency ω ₁ .

The block diagram of the modem is shown in FIG. 1. The structural diagram of a geostationary satellite repeater is shown in FIG. 2. The geometrical arrangement of the geostationary satellite repeater S and two ground stations A and B is shown in FIG. 3. The timing diagram of the duplex clock comparison method is shown in FIG. 4. A frequency diagram explaining the signal conversion process is shown in FIG. 5.

The modem of the signals for transmitting time over a satellite duplex channel contains a geostationary satellite repeater 30, first A and second B ground stations, each of which contains a time and frequency standard 1 connected in series, a second local oscillator 3, a second mixer 14, the second input of which is through switch 13 connected to the first output of the pseudo-noise signal generator 12, an amplifier 15 of a second intermediate frequency, a second power amplifier 16, a first duplexer 5, the input-output of which is connected to the first transceiver antenna 4, first a power amplifier 6, a first mixer 7, the second input of which is connected through the first local oscillator 2 to the first input of the time and frequency standard 1, amplifier 8 of the first intermediate frequency, the first key 23, the first clipper 9, the second input of which is connected to the third output of the time standard 1 and frequency, the first memory unit 10 and the first correlator 11, the output of which is the signal output of the modem. A second clipper 17, the second input of which is connected to the third output of the time and frequency standard 1, and a second memory unit 18, the output of which is connected to the second input of the first correlator 11, are sequentially connected to the second output of the pseudo-noise signal generator 12. The output of the first power amplifier 6 is connected in series a frequency selector 19, the second input of which is connected to the output of the second local oscillator 3, a narrow-band filter 20, the first amplitude detector 21 and threshold block 22, the output of which is connected to the second input of the first key 23. To the output of the key 23, a multiplier 26 is connected in series, the second input of which is connected through a multiplier 13 and an adjustable delay unit 25 to the first output of the pseudo-noise signal generator 12, a low-pass filter 27 and an extreme regulator 28, the output of which is connected to the second input of the adjustable delay unit 26, to the second output of which a range indicator 29 is connected.

The adjustable delay unit 25, the multiplier 26, the low-pass filter 27 and the extreme controller 28 form a second correlator 24.

The geostationary IC3 repeater 30 includes a fourth power amplifier 40, a second duplexer 32, the input-output of which is connected to a second transceiver antenna 31, a third power amplifier 33, a third mixer 35, the second input of which is connected to the output of the third local oscillator 34, and a total amplifier 37 frequency, the second amplitude detector 38 and the second switch 39, the second input of which is connected through the amplifier 36 of the third intermediate frequency to the output of the third mixer 35, and the output is connected to the input of the fourth amplifier 40 awns.

The modem of the signals transmitting time on a duplex satellite communication channel operates as follows.

At point A, using a generator 12, a pseudo-noise microwave signal αi is formed at the first step of single measurements

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

where U _c , ω _s , ϕ _s , T _s - amplitude, carrier frequency, initial phase and duration of the pseudo-noise signal:

ϕ _k (t) = {0, π} is the manipulated component of the phase, which displays the law of phase manipulation in accordance with the pseudo-random sequence (PSP), and ϕ _k (t) = const for 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, ..., N);

τ _e , N is the duration and number of chips from which a pseudo-noise signal of duration T _c (T _c = Nτ _e ) is composed.

This signal from the output of the pseudo-noise signal generator 12 through a closed switch 13 is fed to the first input of the second mixer 14, the second input of which is supplied with the voltage of the second local oscillator 3, stabilized by the standard 1 time and frequency

u _g2 (t) = U _g2 cos (ω _g2 e + ϕ _g2 ).

At the output of the second mixer 14, voltages of combination frequencies are generated. The amplifier 15 is allocated the voltage of the second intermediate (total) frequency

u _CR2 (t) = U _CR2 cos [ω _CR2 t + ϕ _k (t) + ϕ _CR2 (t), 0≤t≤t _s ,

;Where

;

ω _CR2 = ω _s + ω _g2 - the second intermediate (total) frequency;

ϕ _pr2 = ϕ _with -ϕ _g2 ,

which is amplified in the power amplifier 16 and through the duplexer 5 enters the transceiver antenna 4 and is radiated in the direction of the geostationary satellite repeater at a frequency of ω ₁ = ω _pr2 .

However, the same signal is clipped in the second clipper 17 and recorded in the buffer block 18 of the memory. The operation of the clipper 17 is synchronized by the standard 1 time and frequency.

The _pseudo-noise signal u _pr2 (t) received by the antenna 31 is _transmitted through the duplexer 32 and the power amplifier 33 to the first input of the third mixer 35, the second input of which supplies the voltage of the third local oscillator 34

u _g3 (t) = U _g3 cos [ω _g3 t + ϕ _g3 ].

At the output of the third mixer 35, voltages of combination frequencies are generated. Amplifiers 36 and 37 distinguish the voltage of the third intermediate and total frequencies, respectively

u _CR3 (t) = U _CR3 cos [ω _CR3 t + ϕ _k (t) + ϕ _CR3 ],

u _Σ (t) = U _CR3 cos [ω _Σ t + ϕ _k (t) + ϕ _Σ ], 0≤t≤T _c ,

;Where

;

ω _CR3 = ω ₁ -ω ₃ - the third intermediate frequency;

ω _Σ = ω ₁ + ω _g3 is the total frequency;

φ = φ _{PR3 PR3} ip _r3; ϕ _Σ = ϕ _pr2 + ϕ _g3 ;

The tuning frequency ω _{n1 of the} amplifier 37 of the total frequency selected equal to the total frequency ω _n1 = ω _Σ = ω _CR2 = ω _G3 . The voltage of the total frequency u _Σ (t) from the output of the amplifier 37 of the total frequency is fed to the input of the second amplitude detector 38, where its envelope is highlighted. The detected voltage is supplied to the control input of the second key 39, opening it. In the initial state, the key 39 is always closed. In this case, the voltage u _pr3 (t) of the third intermediate frequency from the output of the amplifier 36 through the public key 39 is supplied to the input of the power amplifier 40, and then through the duplexer 32 to the transceiver antenna 31 and is radiated by it back to the ground point A and B at a frequency ω ₂ = ω _CR3 while maintaining phase relationships. The radiation pattern of the airborne transceiver antenna 31 of the satellite repeater 30 is selected so that this signal can be received at both ground points A and B.

The relay satellite received at the ground point A by the transceiving antenna 4 (signal α ₁ ) is supplied through the duplexer 5 and the power amplifier 6 to the first input of the first mixer 7 and the frequency selector 19. The second input of the first mixer 7 is supplied with the voltage of the first local oscillator 2, stabilized by the standard 1 time and frequency

u _g1 (t) = U _gl cos (ω _g1 t + ϕ _g1 ).

At the output of the first mixer 7, voltages of combination frequencies are generated. The amplifier 8 is allocated the voltage of the first intermediate frequency

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

;Where

;

ω _CR1 = ω _{g1 -ω CR3} - the first intermediate frequency;

ϕ _pr1 = ϕ _g1 -ϕ _pr3 .

The second input of the frequency selector 19 is supplied with voltage u _g1 (t) of the second local oscillator 3

As the frequency selector 19 may be used vibrational system, the tuning frequency α _H2 which is selected equal to the frequency of the second local oscillator _z2 α 3 (ω _2n = ω _z2). The output voltage of the frequency selector 19 is extracted by a narrow-band filter 20, detected by the amplitude detector 21 (U) and fed to the input of the threshold unit 22, where it is compared with the threshold voltage U _then . With the resonance that occurs when ω ₂ = ω _g2 , the output voltage of the frequency selector 19 reaches its maximum value, the output voltage of the amplitude detector 21 reaches its maximum value U _max and exceeds the threshold level U _pores in the threshold block 22 (U _max > U _pores ). And only when the threshold level U _{then is} exceeded (this happens only when the resonance occurs), a constant voltage is generated in the threshold block 22, which is supplied to the control input of the key 23 and opens it. In the initial state, key 23 is always closed.

In this case, the voltage u _pr1 (t) from the output of the amplifier 8 of the first intermediate frequency through the public key 23 is supplied to the input of the first clipper 9 and the multiplier 26. The operation of the clipper 9 is synchronized by the standard 1 time and frequency.

A pseudo-noise signal u _c (t) is supplied to the second input of the multiplier 26 through the closed switch 13 and the adjustable delay unit 25 from the first output of the local oscillator 12. The voltage obtained at the output of the multiplier 26 is passed through a low-pass filter 27, at the output of which a correlation function R (τ ), where τ is the current time delay. The extreme controller 28, designed to maintain the maximum of the correlation function R (τ) and connected to the output of the low-pass filter 27, acts on the control input of the adjustable delay unit 25 and maintains the delay τ introduced by it equal to τ ₃ , which corresponds to the maximum value of the correlation function R ( τ).

The scale of the adjustable delay unit 25 is connected with a range indicator 29, which allows you to directly read the measured value of the slant range to the geostationary satellite repeater.

where c is the propagation velocity of electromagnetic waves.

Similar operations are carried out at point B. At the second measurement step (when transmitting a signal from point B), after some time Θ after the end of the signal registration, the switch 13 at point A opens and closes at B. At time t ₃ ^B = t ₂ ^B + Θ, generator 12 begins to generate a new microwave signal (signal β), which, after corresponding conversion, is fixed at point B and emitted in the direction of the geostationary satellite repeater at frequency ω _1. Received by the on-board receiver The satellite repeater signal is re-emitted back to points A and B at a frequency of ω ₂ while maintaining phase relationships in the entire frequency band of the signal. The relay signal is received at both points, converted to low-frequency voltage and relayed at times t ₄ ^A and t ₄ ^B, respectively (signals α ₄ and β ₄ ). This ends the single measurement of the duplex method. Then, in the interval between the measurement acts, the pairs of signals α ₁ , α ₂ and α ₃ , α ₄ (β ₁ , β ₂ and β ₃ , β ₄ ) are subjected to correlation processing in the correlator 11. Correlation processing of two pairs of recorded signals in the interval between two measurements the following time delays are determined in the correlator.

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

;Where

;

a_j, b_l (j = 1, 2, 3) is the 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 приеморегистрирующей аппаратуре;

,

- signal delays in the receiver-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:

где

Where

Where

- задержки сигнала в атмосфере на частотах ω₁ и ω₂ соответственно;

- signal delays 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 quadrangle 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 y for 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.

In points A and B, the equipment works the same way, only the order of steps in them is the opposite. To calculate the difference of the clock Δt, it is enough to exchange the received digital data between the points, which can be done via official communication channels through the same geostationary satellite relay, as shown above, or by telegraph communication channels.

The modem operation described above corresponds to the case of receiving pseudo-noise signals on the main channels at frequencies ω ₁ and ω ₂ .

If a false signal (interference)

_zl u (t) = U _P1 cos (ω t + φ _{P1 P1)} 0≤t≤T _P1,

arrives at the input of the transceiver antenna 4, then it goes through the duplexer 5 and the power amplifier 6 to the first inputs of the mixer 7 and the frequency selector 19. The amplifier 8 is allocated the voltage of the first intermediate frequency

_WP4 u (t) = U _WP4 cos (ω t + φ _{pr1 WP4)} 0≤t≤T _P1,

;Where

;

_pr1 ω = ω _P1 -ω _r1 - the first intermediate frequency;

ϕ _pr1 = ϕ _s1 -ϕ _g1 .

Tuning frequency ω _2n selector 19 selects the frequency equal to the frequency of the second local oscillator ω _z2 3 (ω _2n = ω _z2).

_R2 frequencies ω _P1 and ω are spaced by twice the value of the first intermediate frequency ω _z2 -ω _P1 = 2ω _pr1. Therefore, the frequency selector 19 is not resonant, the output voltage U of the amplitude detector 21 does not exceed the threshold level U _then in the threshold unit 22 (U <U _then ). The key 23 does not open and a false signal (interference) received on the first mirror channel at a frequency ω _s1 is suppressed. For this purpose, the resonance frequency properties of a selector 19 provided in the form of a frequency oscillation circuit tincture ω = ω _{2n r2.}

For a similar reason, false signals (interference) received through other additional (first ω _k1 second ω _k2 ) combination channels are also suppressed.

If a false signal (interference)

u _s2 (t) = U _s2 cos (ω t + φ _{s2 s2),} 0≤t≤T _s2,

at a frequency ω _s2 and any other false signal (interference) is supplied to the outputs of the transceiver antenna 31 through a duplexer 32 and a power amplifier 33 to the first input of the third mixer 35, the second input of which supplies the voltage of the third local oscillator 34

u _g3 (t) = U _g3 cos (ϕ _g3 t + ϕ _g3 ).

At the output of the mixer 35 in this case, voltages are generated that do not fall into the passband of the amplifiers 36 and 37 of the third intermediate and total frequency.

The key 39 does not open and a false signal (interference) received on the second mirror channel at a frequency ω _s2 is suppressed.

For a similar reason, false signals (interference) received via other additional combinational channels are also suppressed.

Thus, the proposed modem, in comparison with the base object and other technical solutions of a similar purpose, provides increased noise immunity and reliability of time transmission via a duplex satellite communication channel. This is achieved by suppressing false signals (interference) received via additional channels, and by automatically measuring the slant range of the geostationary satellite repeater in order to control its position in orbit.

Moreover, to suppress false signals (interference) received via additional channels, a method based on the use of the resonance properties of oscillatory systems and the method of total frequency are used.

It should be noted that the resonance phenomenon is a fundamental principle of the operation of many systems and devices of radio electronics, including the proposed modem.

When converting signals in frequency using a mixer operating on a linear section of the current-voltage characteristic, the voltages of the difference (intermediate) and total frequencies are formed. As a rule, only the voltage of the differential (intermediate) frequency is used. In the proposed technical solution, the voltage of the total frequency is also used to suppress false signals (interference) received via additional channels.

To automatically measure the range of a pre-geostationary satellite repeater, a correlator is used that provides accurate measurement and automatic tracking of the geostationary satellite repeater when moving it. In this case, the correlation function of pseudo-noise signals is used, which has a remarkable property - it has one significant main lobe and a relatively low level of side lobes.

\ All blocks of the proposed technical solution are classic, their technical implementation does not present technical difficulties.

To verify the effectiveness of the proposed modem, mock-ups of devices of a data transmission system and a modem for duplex comparisons of time scales on a satellite channel were developed, experimental studies were carried out, and the characteristics of the created equipment were obtained. In particular, the experimental possibility of comparing time scales through the national geostationary satellite "Yamal-200" with an error of less than 10 ns is shown.

Claims (1)

A modem for transmitting time signals via a satellite duplex channel, containing a geostationary satellite repeater, first and second ground stations, each of which contains a time and frequency standard connected in series, a second local oscillator, a second mixer, the second input of which is connected via a switch to the first output of the pseudo-noise generator a signal, a second intermediate frequency amplifier, a second power amplifier, a first duplexer, the input of which is connected to a first transceiver antenna, a first power amplifier, the first mixer, the second input of which is connected through the first local oscillator to the first output of the time and frequency standard, and the amplifier of the first intermediate frequency, the pseudo-noise signal generator connected in series to the second output of the time and frequency standard, the second clipper, the second input of which is connected to the third output of the time standard and frequencies, the second memory unit and the first correlator, the output of which is the signal output of the modem, connected in series to the third output of the time and frequency standard, the first clipper and the first th memory unit, whose output is connected to a second input of the first correlator, the frequency ω ω _r1 and _r2 of the first and second local oscillators spaced apart by the value of the first intermediate frequency ω _{z1 z2} -ω = ω _pr1, characterized in that it is provided with a selector frequency narrowband a filter, a first amplitude detector, a threshold block, a first key, a multiplier, an adjustable delay block, a low-pass filter, an extreme regulator and a range indicator, and a selector is connected in series to the output of the first power amplifier a signal, the second input of which is connected to the output of the second local oscillator, a narrow-band filter, the first amplitude detector, a threshold block and the first key, the second input of which is connected to the output of the amplifier of the first intermediate frequency, and the output is connected to the second input of the clipper, the multiplier is connected in series to the output of the first key , the second input of which, through a series-connected switch and an adjustable delay unit, is connected to the first output of the pseudo-noise signal generator, a low-pass filter and extreme control a generator, the output of which is connected to the second input of the adjustable delay unit, the range indicator is connected to the second output, the geostationary satellite repeater is made in the form of a fourth power amplifier, a second duplexer, the input-output of which is connected to a second transceiver antenna, and a third power amplifier, the third mixer, the second input of which is connected to the output of the third local oscillator, the total frequency amplifier, the second amplitude detector and the second key, the second input of which preamplifier third intermediate frequency is connected to the output of the third mixer and an output connected to the input of the fourth amplifier, the modem emits a pseudo-noise signal at the frequency ω ₁ = ω _r1 = ω _np2, and receives - at frequency ω ₂ = ω _z2 = ω _PR3, where ω _pr2 and ω _pr3 are the second and third intermediate frequencies, respectively, and the geostationary satellite repeater, on the contrary, emits a _pseudo - _noise signal at a frequency of ω ₂ , and receives it at a frequency of ω ₁ .

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