RU2789416C1 - Method for synchronous reception and processing of a request signal in an autodyne transceiver of an atmospheric radiosonde system - Google Patents

Abstract

FIELD: radars.

SUBSTANCE: invention relates to active response radar and can be used in aerological radiosondes (ARS) of atmospheric radiosonding systems to measure the inclined range to the radiosonde by pulse method, direction finding by angular coordinates and transmission of telemetric information on a single carrier frequency. The method for synchronous reception and processing of a request signal in an autodyne transceiver of an atmospheric radiosonding system consists in receiving electromagnetic radiation in the form of a microwave radio pulse with intra-pulse periodic frequency modulation by means of an antenna, acting on a microwave generator with it, causing autodyne changes with the frequency of the intra-pulse frequency modulation of the request signal of the amplitude of oscillations, average values of current and voltage in the circuit the displacement of the active element, and the autodyne changes of the microwave generator are isolated in the form of a radio pulse at the frequency of the intra-pulse frequency modulation of the request signal. The average frequency of the modulated oscillations of the microwave generator is preliminarily combined with the average frequency of the emission of microwave radio pulses with intra-pulse periodic frequency modulation of the request signal. The deviation of the frequency of the request signal is limited by the condition that it is located inside the synchronization band of the microwave generator.

EFFECT: invention enables to expand the operating range of the range into the area of small distances (from tens to about hundreds of meters) of the atmospheric radiosonding system; narrowing of the operating frequency band occupied by the radiosonding system; to expans the dynamic range in terms of the request signal level.

1 cl, 2 dwg

Description

SUBSTANCE: invention relates to active response radar and can be used in upper-air radiosondes (ARZ) of atmospheric radiosonde systems for measuring the slant range to the radiosonde by the pulse method, direction finding by angular coordinates and transmission of telemetric information on one carrier frequency.

A known method of radar sounding with an active response, which in addition to determining the coordinates of the ARZ is also used to transmit various telemetry information. An example of the application of this method is the tracking system for meteorological ARP, developed by the British company Crowley (see pp. 78-82, [1]; pp. 38-41, [2]). In this system, the ARZ coordinates are determined by the ground-based radar interrogator based on the received signals from the transponder, which is located on board the ARZ. Simultaneously with the determination of coordinates, telemetric information about the state of the atmosphere (pressure, humidity and temperature) transmitted by the transponder is recorded.

The complexity, bulkiness and high energy consumption of the known radio sounding system are its disadvantages. The presence of separate antennas, transmitter and receiver for different frequency ranges (see Fig. 26, p. 79, [1]; p. 40, Fig. 20, [2]) significantly complicates and increases the cost of the transceiver device of the APR on-board equipment, which is one-time. In addition, the large dimensions and weight of this equipment pose a safety hazard to aviation.

The super-regenerative transceivers (SRTs) proposed in the 1950s were first used in aviation friend-foe identification systems (see p. 21, Fig. 6, [1]). These transceivers are distinguished by their extremely simple design, low weight and dimensions due to the multifunctionality of the self-oscillator in the super-regenerative mode. Later, due to the noted qualities, SPPs began to be used on board ARZ as transponders in domestic atmospheric radio sounding systems (see pp. 41-45, [2], USSR inventor's certificate: SU115078, publ. 01.01.1958, [3]) .

The high sensitivity of the SPP to the radio pulse interrogation signal makes it possible to form a response signal in range in the form of a short pause in the radiation of the transceiver at a reduced power of the radio pulse of the radio transmitter of the interrogation radar system (RLS). Sufficiently powerful SPP radiation provides reliable tracking of the ARP in terms of angular coordinates and range, as well as simultaneous transmission of telemetric information about the state of the atmosphere by modulating the frequency of superimposed pulses up to distances of 100–150 km [3]. Further development of the theory and technology of the SPP made it possible to improve its parameters and increase the tracking range of ARP by almost a factor of two [4, 5].

The method for receiving and processing an interrogation signal used in the operation of known SPPs with external superization consists in the fact that the electromagnetic microwave radiation of the ground-based radar of the atmospheric radio sounding system is received by an antenna, converted into microwave oscillations of the interrogation radio pulses, and acted upon by the microwave generator at the time of the start of the regenerative the self-oscillation amplitude growth process, amplify and detect the reaction of the microwave generator with the inertial auto-bias circuit of the active element, and then form a response pause in the radiation of the microwave generator under the condition of exposure to a request radio pulse of sufficient amplitude. At the same time, the parameters of the superimposed pulses are modulated in frequency by a radio telemetry signal for transmitting meteorological data from the ARP board to the ground-based radar of the atmosphere radio sounding system (see RF patent RU 2345379 C1, publ. 27.01.2009, bull. No. 3)

However, the known method and devices that implement it have significant drawbacks.

1. Insufficient sensitivity of the SPP in the receive mode, which is limited by shock oscillations inherent in the super-regenerative mode of operation of the microwave generator during the formation of the leading edge of the radio pulse (see pp. 140-146, monograph [6]; Fig. 4, RF patent RU 2345379 C1, Published January 27, 2009, Bulletin No. 3; Fig. 4, RF patent RU 2470323 C1, published December 20, 2012, Bulletin No. 35; article [7]).

2. The asynchrony of the processes of forming the receiving window of the SPP and sending interrogating radio pulses of the ground-based radar causes additional fluctuations in the time position, depth and duration of the response pause (see Fig. 5 of the RF patent RU 2368916 C2, publ. 27.09.2009, bull. No. 27; p. 566, Fig. 4.4.18 of monograph [5]). This is the reason for the fundamentally unremovable component of the additional error in measuring the slant range.

3. Insufficient noise immunity of the NGN from the effects of active interference. When interference occurs at the receiving frequency, the SPS generates false response pauses, which, with prolonged exposure to interference, disrupt the operation of the channels for measuring the range and receiving telemetry information of the radio sounding system.

4. The wide emission spectrum of the SPP and its noise nature creates problems of electromagnetic compatibility, for example, in the operation of GLONASS/GPS systems (see pp. 532-537, Fig. 4.3.34, [5]). The half-power spectrum width is usually 6...8 MHz, depending on the duration of the generated radio pulses (see Fig. 36, p. 103, [8]; see Fig. 2 of the RF patent RU 2368916 C2, publ. 27.09.2009, bul. 27).

Free from these disadvantages is the method of receiving and processing the interrogation signal used in the operation of the autodyne transceiver (ALL) according to the patent of the Russian Federation RU 2624993 C1 (publ. 11.07.2017, bull. No. 20) [9].

The method for receiving and processing the request signal of an analog device in accordance with the description of the principle of its operation consists in the following sequence of actions. The radio pulse of the request signal in the form of electromagnetic microwave radiation of the ground-based radar of the atmospheric radio sounding system is received by the antenna AMS, converted into microwave oscillations of the radio pulse of the request, the oscillations are sent to the resonant system of the microwave generator, mixing them with the natural oscillations of the microwave generator, the resulting mixture is converted by means of a microwave generator into an autodyne response in the form of changes in the amplitude of oscillations and the average value of current and voltage in the bias circuit of the active element, by means of a recording device, the autodyne response of the microwave generator is isolated in the form of a radio pulse of an intermediate frequency of the beat signal, after which the radio pulse is sequentially amplified in amplitude, filtered by a bandpass filter, then by amplitude detection, the radio pulse is converted into a video pulse, its amplitude is compared with the threshold level, selection is made according to the time parameters of the request signal, and a response pause pulse is formed, which interrupts the radiation of the microwave generator, at In this case, in the time intervals between receiving the interrogation signals, the frequency of the microwave generator is modulated by a radio telemetry signal for transmitting meteorological data from the ARP board to the ground-based radar of the atmosphere radio sounding system, and the frequency of the microwave generator is preliminarily detuned from the frequency of the radar interrogation signal by more than half-width of the synchronization bandwidth.

However, the analog device has the following significant disadvantages.

, где Δω_пс - значение полуширины полосы синхронизации (см. стр. 38, [10]). Однако значение частоты биений ω_б ограничено сверху граничной частотой Ω_гр СВЧ-генератора, наличие которой обусловлено его внутренней инерционностью. Эта инерционность характеризуется постоянной времени τ_а автодинного отклика, по значению которой можно рассчитать граничную частоту Ω_гр (см. формулу (34) статьи [11]):1. The behavior of the AMS that implements the described method depends in a complex way on the ratio of the beat frequency and the synchronization bandwidth of the microwave generator. For the normal functioning of the AMS, it is necessary to provide a mode close to linear in the microwave generator, in which the shape of the beat approaches a sinusoidal one. In this case, the beat frequency ω _b should be far from the synchronization band of the microwave generator:

, where Δω _ps is the half-width of the synchronization bandwidth (see p. 38, [10]). However, the value of the beat frequency ω _b is limited from above by the boundary frequency Ω _gr of the microwave generator, the presence of which is due to its internal inertia. This inertia is characterized by the time constant τ _{a of} the autodyne response, by the value of which it is possible to calculate the boundary frequency Ω _gr (see formula (34) of article [11]):

Where

раза по сравнению с уровнем сигнала в области низких частот;Ω _gr - cutoff frequency at which the signal level in amplitude drops to

times compared to the signal level in the low frequency region;

τ _a - characteristic time constant (relaxation time) of the autodyne response;

ω ₀ - central (working) frequency of the microwave generator AMS;

ρ is the coefficient of nonisodromicity of the AMS microwave generator;

K _a - coefficient of autodyne gain of the microwave generator;

Q _ext - external quality factor of the oscillatory system of the microwave generator.

При остальных, входящих в (1) значениях параметров:

получим частоту

т.е. 8,5 МГц. Отсюда следует ограничение сверху на выбор частоты сигнала биений, т.е. частота биений должна быть не более величины

граничной частоты

В данном примере значение частоты

составляет 8,5 МГц.The autodyne gain coefficient _Ka in (1) shows how many times the autodyne changes in the amplitude of the microwave generator oscillations are greater than the amplitude of the radar interrogation signal that came into its resonator. Under this condition, the influence of the intrinsic noise of the microwave generator on its sensitivity as a receiver is reduced. But the increase in this coefficient, as can be seen from (1), also affects the value of the boundary frequency Ω _gr . Take for example the compromise value

For the remaining values of the parameters included in (1):

We get the frequency

those. 8.5 MHz. This implies an upper bound on the choice of the frequency of the beat signal, i.e. beat frequency should be no more than

boundary frequency

In this example, the frequency value

is 8.5 MHz.

где полуширина полосы

синхронизации СВЧ-генератора. Величина

в свою очередь, определяется относительным уровнем запросного сигнала (см. стр. 257-262, формулу (5.73), [12]):On the other hand, the AMS must satisfy the above strong inequality

where is the half-width of the band

synchronization of the microwave generator. Value

in turn, is determined by the relative level of the request signal (see pp. 257-262, formula (5.73), [12]):

Where

- полуширина полосы синхронизации СВЧ-генератора АПП;

- half-width of the synchronization band of the AMS microwave generator;

- коэффициент относительного уровня сигнала запроса;

- coefficient of the relative level of the request signal;

P _zap - the power of the request signal of the radar coming into the resonator of the microwave generator AMS;

P _out - output power of the APP microwave generator;

ω ₀ - central (working) frequency of the microwave generator AMS;

Q _ext - external quality factor of the oscillatory system of the APP microwave generator;

- угол между линией прибора (активного элемента) СВЧ-генератора и его линией годографа импеданса колебательной системы и нагрузки (см. рис. 5.16, стр. 260, [12]);

- the angle between the line of the device (active element) of the microwave generator and its line of the hodograph of the impedance of the oscillatory system and the load (see Fig. 5.16, p. 260, [12]);

γ - generator non-isochronism factor.

что соответствует расстоянию в десятки метров от РЛС до АРЗ, на частоте

при

и

получаем

т.е. 34 МГц. Это означает, что в диапазоне малых расстояний, от места пуска АРЗ и до порядка нескольких сотен метров, расширение полосы синхронизации препятствует нормальной работе АПП.As a result of the calculation of the half-width of the synchronization band by formula (2) at

which corresponds to a distance of tens of meters from the radar to the ARP, at a frequency

at

And

we get

those. 34 MHz. This means that in the range of short distances, from the launch site of the ARZ to about several hundred meters, the expansion of the synchronization band prevents the normal operation of the AMS.

This implies the limitation of the parameters of the known device in terms of range. It does not ensure the normal operation of the atmospheric radio sounding system in the range of small distances (from tens to about hundreds of meters), where data on the state of the surface layers of the atmosphere are also in demand for many consumers.

то занимаемая системой радиозондирования полоса частот

как минимум, равна удвоенному значению частоты сигнала биений

и может составлять исходя из полученных выше расчетов порядка 17 МГц. Тогда как ширина спектра запросного сигнала РЛС не более 1 МГц (см. рис. 136, [13]). Поэтому полоса разноса несущих частот излучения АПП и запросной РЛС является неоправданно широкой и создает проблемы электромагнитной совместимости иным радиосистем, например, работе систем ГЛОНАСС/GPS (см. стр. 532-537, рис. 4.3.34, [5]).2. Since the frequency ω _zap of the request signal can be both lower and higher relative to the average (working) frequency ω ₀ AMS by the value of the frequency ω _b of the beat signal

then the frequency band occupied by the radio sounding system

at least equal to twice the frequency of the beat signal

and can be, based on the above calculations, about 17 MHz. Whereas the bandwidth of the radar interrogation signal spectrum is not more than 1 MHz (see Fig. 136, [13]). Therefore, the separation band of the carrier frequencies of the radiation of the AMS and the interrogation radar is unreasonably wide and creates problems of electromagnetic compatibility for other radio systems, for example, the operation of GLONASS / GPS systems (see pp. 532-537, Fig. 4.3.34, [5]).

3. In the range of short ranges from the radar to the ARP, as noted, the request signal is strong and a number of undesirable nonlinear phenomena can be observed in the AMS. So, in the mode of high level of the request signal, the synchronization band expands significantly (2) and its boundary value can approach the frequency of the request signal. Under these conditions, natural oscillations of the microwave generator are subject to significant amplitude and frequency modulation (see pp. 37-42, [10]). The spectrum of these oscillations "splits" into harmonics (see Fig. 27, [14]) of beat frequencies, which create additional interference to radio equipment. In this case, the output low-frequency beat signal at the output of the APC microwave generator is formed with anharmonic distortions (see pp. 37-42, Fig. 1.14, [10]; article [15]), which create problems during its processing. In addition, in the high level mode of the interrogating radar signal, the beat signal may exit the passband of the band pass filter, as well as the acquisition of the ATC frequency. In both cases, there is no beat signal at the AMS output and the radio sounding system cannot function normally. This implies another drawback - the limitation of the dynamic range of the AMS from above in terms of the level of the input signal of the request.

Thus, the technical problem to be solved by the claimed invention consists in the simultaneous solution of a number of heterogeneous problems, namely: expanding the operating range of the range into the region of small distances (from tens to about hundreds of meters) of the atmospheric radio sounding system; narrowing the operating frequency band occupied by the radio sounding system; expanding the dynamic range by the level of the request signal.

The solution to this problem is to use the properties of radio signals transmitted from the radar of the atmospheric radio sounding system to the ARP, and the modes of operation of autodyne transceivers. The essence of this solution is to use oscillations with periodic intra-pulse frequency modulation as a carrier of an interrogating radio pulse and to transfer the microwave generator from the mode of an asynchronous autodyne frequency converter to the mode of a synchronous detector (converter) of frequency modulation.

To solve this problem, a method is proposed for synchronous reception and processing of an interrogation signal in an autodyne transceiver of an atmosphere radio sounding system, which consists in receiving electromagnetic radiation in the form of a microwave radio pulse with intra-pulse periodic frequency modulation by means of an antenna, acting on the microwave generator, causing capture and synchronization the frequency of oscillations of the microwave generator, as well as autodyne changes with the frequency of intra-pulse frequency modulation of the request signal of the amplitude of oscillations, the average values of current and voltage in the bias circuit of the active element, highlight the autodyne changes of the microwave generator in the form of a radio pulse at the frequency of intra-pulse frequency modulation of the request signal, after that this radio pulse at the frequency of interpulse frequency modulation of the interrogating signal is sequentially amplified in amplitude, filtered and converted into a video pulse, then the amplitude of the video pulse is compared with the threshold level and when exceeding amplitude of the video pulse of the threshold level, a pulse is formed, the duration of which is compared with the specified duration of the request signal, then, if they are equal, a response pause pulse is formed, which interrupts the radiation of the microwave generator, while the frequency of the microwave generator in the time intervals between the moments of receiving the request signals and the formation of the response pauses are modulated by a radio telemetry signal, wherein the average frequency of the modulated oscillations of the microwave generator is pre-combined with the average frequency of the radiation of microwave radio pulses with intra-pulse periodic frequency modulation of the interrogation signal, and the frequency deviation of the interrogation signal is limited by the condition of its being within the synchronization band of the microwave generator.

Comparison of the proposed method of synchronous reception and processing of the request signal with the method that underlies the principle of operation of the analog transceiver shows the presence of a change in the mode of receiving request signals and the operation of the microwave generator, which ensure the achievement of a positive effect. As a result of the search for alternative solutions in this and related areas of application of AMS and radar transponders among various sources, it has been established that known devices differ in the composition of actions and their sequences. Among these sources, ed. certificates of the USSR SU 671515 A1 (publ. 30.03.1984, bull. No. 12); SU 854163 A1 (published May 30, 1992, Bull. No. 20); SU 1818605 A1 (published May 30, 1993, Bull. No. 20); RF patents RU 2096805 C1 (publ. 20.11.1997); RU 2191403 C1 (published on October 20, 2002, Bull. No. 29); RU 2193783 C2 (published on November 27, 2011, Bull. No. 33); RU 2242020 C2 (published on July 10, 2004, Bull. No. 19); RU 2321021 C1 (published on March 27, 2008, Bull. No. 9); RU 2338221 C1 (published on November 10, 2008, Bull. No. 31); RU 2343501 C1 (published on January 10, 2009, Bull. No. 1); utility model patents of the Russian Federation RU 166135 U1 (publ. 20.11.2016, bull. No. 32), RU 87542 U1 (publ. 10.10.2009, bull. No. 28), RU 116650 U1 (publ. 27.05.2012, bull. No. 15); fig. 1 and 2 of US Pat. 489, Fig. 7, [18]; pp. 497-501, Fig. 11.1, [19]; pp. 83-86, Fig. 3.18, [20]; pp. 758-774, Fig. 14.12, [21 ]; pp. 43-47, Fig. 2.18, [22]). Thus, the search results allow us to conclude that the proposed solution meets the "Novelty" criterion.

The technical essence of the invention lies in the fact that the transfer of the microwave generator from the mode of asynchronous reception of a request signal to the synchronous mode of receiving frequency-modulated radio signals expands the dynamic range in terms of the level of the request signal, the operating range of the range to the region of small distances (from tens to about hundreds of meters) and narrows the frequency band occupied by the radiosonde system. The proposed mode of operation of the microwave generator is described in the public literature. However, its use in the proposed method provides opportunities that do not explicitly follow from the prior art, which corresponds to the criterion of "Inventive step".

The invention is aimed at improving the performance of radio sounding systems designed to obtain meteorological data on the state of the atmosphere, which is necessary for various branches of human activity. Thus, the claimed invention meets the criterion of "Industrial applicability".

The essence of the invention is illustrated by the drawing in Fig. 1, which shows a block diagram of an autodyne synchronous transceiver (ASTS). In FIG. 2 shows characteristics and timing diagrams that explain the principle of converting a frequency modulated radio signal into an information signal by means of a synchronized microwave generator.

ASS of the atmospheric radio sounding system, which implements the proposed method for synchronous reception and processing of a request signal, contains (see Fig. 1) series-connected antenna 1, a microwave generator 2 with the possibility of electrically controlling the frequency and turning it off, an autodyne signal recording device 3, an amplifier 4, band-pass filter 5, linear amplitude detector 6, comparator 7, time selector 8 and shaper 9 of response pause pulses, the output of which is connected to the control input of turning off the microwave generator 2 (see RF patent RU2624993C1, publ. 11.07.2017, bull. No. 20 , [9]).

Antenna 1 can be of various designs, depending on the requirements for the radiation pattern and the operating frequency range, for example, in the form of an asymmetric quarter-wave vibrator according to FIG. 4 and 8 of the RF patent RU 2214614 C2 (publ. 20.10.2003, bull. No. 29), slot or strip vibrator, horn, dielectric rod, helical antenna or type "wave channel" (see respectively p. 115, 149, 218 , 239, 260, [23]).

The microwave generator 2 can be made, for example, in the form of a microwave generator module based on a transistor (see Figs. 7 and 8 of patent RU 2345379 C1, publ. 27.01.2009, bull. No. 3), on a Gunn diode or transit diode (see pp. 194, 195, fig. 4.24 and 4.25, [24]). To ensure modulation of the generation frequency by a telemetry signal, a varicap can be placed in the resonator of the microwave generator (see pp. 80-84, [25]) or the method of modulation by changing the supply voltage can be used (see Fig. 18, article [26]).

The autodyne signal recording device 3 also has alternative technical solutions. For example, when registering a signal in the power circuit of a microwave generator 2, device 3 can be made in accordance with one of the circuits shown in Fig. 14 of the article [26], or according to the scheme with transformer-capacitive coupling of circuits (see Fig. 74, monograph [27]). In the case of registering a signal by changing the amplitude of oscillations, the device 3 for registering the converted signal is usually based on a detector diode. This diode is placed directly in the cavity of the microwave generator 2 or in a transmission line connected to the cavity, as shown in FIG. 2 patents of the Russian Federation RU 2295911 C1 (published on March 27, 2007, bull. No. 9) and in fig. 6a and 9a of [26].

The autodyne signal amplifier 4 can be made in the form of a conventional bandpass amplifier with a linear or logarithmic amplitude characteristic in the operating range of signal levels (see, for example, p. 60, Fig. 4.3, [28]).

As a bandpass filter 5, a filter on surface acoustic waves (SAW) can be used, with a central frequency equal to the frequency of the converted autodyne signal, and its bandwidth P _SAW is determined by the condition for the passage of the request radio pulse without significant distortion: P _SAW ≈6/t _n , where t _n - pulse duration (see Fig. 4.22, p. 72, pp. 241-243, [28]). As a linear amplitude detector 6, a diode amplitude detector can be used, made according to a serial or parallel circuit (see Fig. 7.1, p. 123, Fig. 7.8, p. 131, [28]). Comparator 7 can be made on a K521SAZ chip according to the electrical circuit shown in fig. 6.7b, p. 170, [29]. The time selector 8 of the pulses can be made according to one of the electrical circuits of the pulse duration selectors shown in Fig. 6.8 and described on pages 117-119 of the book [30], as well as on pages 509-511, 516-517, [31]. The shaper 9 of the response pause pulse can be made on the timer chip KR1006 VI1 (see Fig. 7.6, p. 191, [29]).

APCS that implements the claimed method works as follows.

When applying to the device supply voltage in the microwave generator 2 (see Fig. 1) there are microwave oscillations at a frequency ω ₀ that are emitted by the antenna 1 in the form of electromagnetic waves into the surrounding space. In this case, the telemetry signal U _ST supplied to the varicap built into the cavity of the microwave generator 2 or to its power supply circuit (see Fig. 18, article [26]) causes narrow-band frequency modulation of this radiation.

In accordance with the operation principle of the radar station (RLS) (see pp. 74-87, [5]), the radio receiver of the radar, using a directional antenna, receives a telemetry signal from the ARZ, detects and decrypts it, and records data. At the same time, the antenna drive and control systems measure the angular coordinates of the ARZ position relative to the radar, which, together with data on the distance to the ARZ, determine the wind speed and direction. Note that in the process of receiving ARP signals, the automatic frequency control system (AFC) of the radar corrects the frequency of the transmitter master oscillator to a frequency close to the average frequency ω ₀ of the radiation of the microwave generator 2 of the ASPP.

Заполняющие эти радиоимпульсы СВЧ колебания подвергнуты узкополосной частотной модуляции (ЧМ) квазигармоническими колебаниями с частотой порядка 10…20 МГц и постоянной величиной девиации частоты. Сформированные таким образом в передатчике РЛС радиоимпульсы далее с помощью направленной антенны РЛС излучаются в виде электромагнитных (ЭМ) волн в направлении АРЗ.The radar transmitter generates periodic microwave radio pulses of the request at a frequency ω _ref with a repetition period T _p and a duration t _app. For example,

The microwave oscillations filling these radio pulses are subjected to narrow-band frequency modulation (FM) by quasi-harmonic oscillations with a frequency of the order of 10 ... 20 MHz and a constant frequency deviation. The radio pulses formed in this way in the radar transmitter are further radiated by means of a directional radar antenna in the form of electromagnetic (EM) waves in the direction of the ARP.

The EM radiation received on board the ARZ by antenna 1 at a frequency ω _zarr is converted into electrical oscillations, which, in the form of request radio pulses with intrapulse frequency modulation, enter the resonator of the microwave generator 2. Here they are mixed with the natural oscillations of the microwave generator 2, having a frequency ω ₀ , which may slightly differ from the frequency ω _lock due to temperature shifts during the rise of the ARP and natural instabilities. The mixture of oscillations formed in the resonator, interacting on the nonlinearity of the active element of the microwave generator 2, causes a number of nonlinear phenomena in its self-oscillatory system.

One of the fundamental phenomena characteristic of these systems is that if the frequency of the signal acting on the microwave generator 2 is within its synchronization band, then its frequency is captured and held accurate to a phase shift. In this case, changes in the frequency and phase of the acting radio signal cause corresponding changes in the frequency and amplitude of the oscillations of the microwave generator 2, as well as the average value of the bias (current or voltage) of the active element. This phenomenon is widely described in the literature [10, 12, 14], and its applications are also noted, for example, it is used to detect frequency-modulated (FM) oscillations (see pp. 175-178, [32]).

In FIG. 2 shows diagrams explaining the principle of FM demodulation by means of a synchronized microwave generator 2. The diagrams under the letter "A" show the amplitude-frequency characteristics (AFC) a _n (χ) normalized relative to the maximum values, obtained for various values of the coefficient γ of the non-isochronism of the microwave generator 2: γ = 0 (curve 1); γ=0.5 (curve 2); γ=1 (curve 3); γ = 5 (curve 4) [13]. These characteristics show the dependence of the normalized value of changes in the amplitude of oscillations of the microwave generator 2 a _n (χ) (respectively, the response in the power circuit), on the value of the relative frequency detuning χ of the request signal from the center frequency ω ₀ of the microwave generator 2 within the boundaries of the synchronization band,

Where

- относительная отстройка частоты ω_с запросного сигнала от центральной частоты ω₀ СВЧ-генератора 2;

- relative frequency detuning ω _from the request signal from the central frequency ω ₀ of the microwave generator 2;

- полуширина полосы синхронизации;

- synchronization band half-width;

- абсолютная величина отстройки частоты запросного сигнала от середины полосы синхронизации;

- the absolute value of the frequency detuning of the interrogating signal from the middle of the synchronization band;

ω ₀ - the center frequency of the synchronization band of the microwave generator 2;

- коэффициент относительного уровня сигнала запроса;

- coefficient of the relative level of the request signal;

R _with , R ₀ - the power of the received request signal and the output power of the microwave generator 2, respectively;

γ - coefficient of non-isochronism of the microwave generator 2;

Q _ext - external quality factor of the oscillatory system of the microwave generator 2.

The diagram under the letter "B" shows the timing diagram χ(t) of instantaneous changes in the frequency of the request signal acting on the microwave generator 2 in the center of the synchronization band. The value of the frequency deviation of this signal is taken equal to half the half-width of the synchronization bandwidth.

The diagram under the letter "B" shows the timing diagram and _n (t) of the output signal for the case of a microwave generator 2, having a coefficient of non-isochronism γ=5 (see curve 4 in the diagram under the letter "A"). High values of the nonisochronism coefficient γ are typical for real microwave generators made on semiconductor devices (see Fig. 2.10, p. 48, Fig. 2.22, p. 64, [32]). In addition, the presence of a varicap in the oscillatory system, as a rule, additionally increases the value of the coefficient γ of the nonisochronism of the microwave generator 2.

From the graphs presented, it can be seen that with an increase in the nonisochronism coefficient γ, the frequency response of the synchronized microwave generator 2 degenerates almost into a straight line (see curve 4 in the diagram under the letter "A"). This type of frequency response ensures high linearity of the FM conversion into changes in the oscillation amplitude. In this case, the detection of changes in the amplitude of oscillations using an external detector or their auto-detection in the power circuit by means of the recording device 3 provides an almost linear FM demodulation.

It should be noted that on both axes of the frequency response (see Fig. 2) the denormalized variables Δ4 (vertically) and Δω _c (horizontally) equally (directly proportional) depend on the relative level of the request signal Г _c :

Where

Δ4 - absolute changes in the amplitude of oscillations of the microwave generator 2;

- нормированная величина изменений амплитуды колебаний СВЧ-генератора 2;

- normalized value of changes in the amplitude of oscillations of the microwave generator 2;

A ₀ - amplitude of stationary oscillations of autonomous microwave generator 2;

- коэффициент относительного уровня сигнала запроса;

- coefficient of the relative level of the request signal;

P _c , P ₀ - the power of the received request signal and the output power of the microwave generator 2, respectively;

K _a - coefficient of autodyne gain of the microwave generator 2;

- абсолютная величина отстройки частоты запросного сигнала от середины полосы синхронизации СВЧ-генератора 2;

- the absolute value of frequency detuning of the interrogating signal from the middle of the synchronization band of the microwave generator 2;

- относительная отстройка частоты ω_c запросного сигнала от центральной частоты ω₀ СВЧ-генератора 2;

- relative frequency detuning ω _c of the interrogation signal from the central frequency ω ₀ of the microwave generator 2;

- полуширина полосы синхронизации;

- synchronization band half-width;

ω ₀ - the center frequency of the synchronization band of the microwave generator 2;

γ - coefficient of non-isochronism of the microwave generator 2;

Q _ext - external quality factor of the oscillatory system of the microwave generator 2.

получим формулу для расчета крутизны характеристики преобразования СВЧ-генератором 2 ЧМ запросного радиоимпульса в напряжение преобразованного сигнала:Taking the ratio of expressions (3) and (4) taking into account that the maximum values

we obtain a formula for calculating the steepness of the characteristics of the conversion of the microwave generator 2 FM interrogative radio pulse into the voltage of the converted signal:

- максимальные изменения амплитуды колебаний СВЧ-генератора 2;

- maximum changes in the amplitude of oscillations of the microwave generator 2;

- абсолютная отстройка частоты запросного сигнала от середины полосы синхронизации СВЧ-генератора 2;

- absolute frequency detuning of the interrogating signal from the middle of the synchronization band of the microwave generator 2;

A ₀ - amplitude of stationary oscillations of autonomous microwave generator 2;

K _a - coefficient of autodyne gain of the microwave generator 2;

ω ₀ - the center frequency of the synchronization band of the microwave generator 2;

γ - coefficient of non-isochronism of the microwave generator 2;

Q _ext - external quality factor of the oscillatory system of the microwave generator 2;

- максимальные изменения частоты запросного сигнала.

- maximum changes in the frequency of the interrogation signal.

дает значение крутизны S_ЧМ = 18 мВ/МГц. При величине девиации частоты, например,

(0,5 МГц) амплитуда преобразованного сигнала на выходе СВЧ-генератора 2 и, соответственно, на выходе устройства 3 регистрации сигнала по изменению амплитуды колебаний (с помощью, так называемого, внешнего детектора) составляет 9 мВ. При выделении сигнала с помощью устройства регистрации в цепи питания амплитуда сигнала определяется его параметрами преобразования изменений тока или напряжения смещения активного элемента в напряжение выходного сигнала [26].From the obtained formula (5) it can be seen that the steepness S of _{the FM} conversion characteristics of the FM in the autodyne response of the microwave generator 2 does not depend on the level of the request signal. Calculation at A ₀ =5 V, K _a =2, Q _ext =100 and γ=5 at carrier frequency

gives the slope value S _FM = 18 mV/MHz. With a frequency deviation value, for example,

(0.5 MHz), the amplitude of the converted signal at the output of the microwave generator 2 and, accordingly, at the output of the device 3 for recording the signal by changing the amplitude of the oscillations (using the so-called external detector) is 9 mV. When a signal is isolated using a recording device in the power circuit, the signal amplitude is determined by its parameters for converting changes in the current or bias voltage of the active element into the output signal voltage [26].

Thus, the request signal in the form of a microwave radio pulse by the microwave generator 2 is converted into a radio pulse filled with frequency modulation frequency fluctuations of the radiation, while its amplitude at a constant frequency deviation is directly proportional to the amplitude of the signal of the request microwave radio pulse. It should be noted that the frequency deviation value is selected at the minimum level of the interrogation signal, which corresponds to the maximum range from the radar to the ARP. This ensures the stability of the automatic transmission system in the entire range of ranges from tens of meters to a range limited by the energy potential of the system and the terrain.

After amplification in amplifier 4, this radio pulse is frequency-selected by a bandpass filter 5, then it is detected by a linear amplitude detector 6, receiving video pulses, and, if the threshold level of the comparator 7 is exceeded, the received pulses from the output of the comparator 7 are fed to the input of the time selector 8 request pulses. The time selector 8 pulses in accordance with the duration and repetition period of the received pulses to the time parameters of the request signals of the radar, generates a pulse input to the shaper 9 pulse response pause.

The response pause pulse shaper 9 produces a short-term (of the order of 1 ... 2 μs) interruption of the operation of the microwave generator 2 and, accordingly, the transmission of electromagnetic waves from the microwave generator 2 to the antenna 1. This interruption is achieved in the simplest case by electronically turning off the power of the microwave generator 2.

In accordance with the principle of operation of the radar (see pp. 74-87, [5]), according to the time position of the pause received by the radio receiver of the radar relative to the moment of sending the interrogating radio pulse, the slant range to the ARP is measured, which is necessary along with the angular coordinates to determine the current coordinates of the location of the radiosonde . At the same time, the time delay introduced by the proposed device associated with the reception, processing and formation of a response pause is easily taken into account when calibrating the radar.

The microwave generator 2 in the device, made according to the proposed method of synchronous reception and processing of request signals, operates with practically continuous radiation in the mode of stationary oscillations of an autodyne synchronous converter of narrow-band frequency-modulated request radio pulses. At the same time, the microwave generator 2 in the time intervals between the moments of receiving the request signals is a narrow-band frequency-modulated transmitter of information of the ARP telemetry channel. Narrow-band frequency modulation and the formation of response pauses by short interruptions of the microwave generator 2 does not significantly affect its mode of operation and the emission spectrum. The exclusion of the frequency separation between the interrogation radar and the automatic transmission system significantly reduced the bandwidth occupied by the atmospheric radio sounding system, which reduced the likelihood of interference with the operation of other radio engineering systems, including the GLONASS/GPS systems.

Thus, the proposed method for synchronous reception and processing of interrogation signals of the atmospheric radio sounding system, while maintaining the functionality of known analogs, ensures the achievement of the technical result of the invention - increasing the stability of the mode and the reliability of the microwave generator in a wide range of distances, from the launch site of the ARP to its range limit, limited by the energy potential of the automatic transmission system and the terrain, as well as expanding the dynamic range in terms of the level of the request signal and solving the problem of electromagnetic compatibility with other systems.

At the same time, it should be added that when using the proposed method for synchronous reception and processing of interrogation signals in existing radio sounding systems, it will require only minor design changes in the radar, associated with the introduction of a frequency detector into the telemetry signal reception channel, and a frequency modulator of the interrogation transmitter. The experimental results obtained for the APCS layout based on a transistor generator at a frequency of 1780 MHz confirmed the possibility of implementing the proposed method [13].

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Claims (1)

A method for synchronously receiving and processing an interrogation signal in an autodyne transceiver of an atmosphere radio sounding system, which consists in receiving electromagnetic radiation in the form of a microwave radio pulse with intra-pulse periodic frequency modulation by means of an antenna, acting on the microwave generator, causing capture and synchronization of the microwave generator oscillation frequency , as well as autodyne changes with the frequency of intra-pulse frequency modulation of the interrogation signal of the oscillation amplitude, average values of current and voltage in the bias circuit of the active element, allocate autodyne changes of the microwave generator in the form of a radio pulse at the frequency of intra-pulse frequency modulation of the interrogation signal, after which this radio pulse at the frequency of the intra-pulse frequency modulation of the request signal is sequentially amplified in amplitude, filtered and converted into a video pulse, then the amplitude of the video pulse is compared with the threshold level and, if the amplitude of the video pulse exceeds the threshold levels, a pulse is formed, the duration of which is compared with the specified duration of the request signal, then, if they are equal, a response pause pulse is formed, which interrupts the radiation of the microwave generator, while the frequency of the microwave generator in the time intervals between the moments of receiving the request signals and the formation of the response pause is modulated by a radio telemetry signal , moreover, the average frequency of the modulated oscillations of the microwave generator is pre-combined with the average frequency of the radiation of microwave radio pulses with intra-pulse periodic frequency modulation of the interrogation signal, and the frequency deviation of the interrogation signal is limited by the condition of its being within the synchronization band of the microwave generator.

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