Field of the Invention

10001 1 The present invention relates to hydrometeorology, in particular, active methods and devices for acting on atmospheric formations and their controlling, hail alerting and prevention, and may be used for automatic realization of anti-hai l protection of agricultural fields, gardens and various publ ic and social objects.

Background of the Invention

1 0021 Several anti-hail protection methods are known in the art. It is known an anti-hail protection method with an active effect (impact) on hail clouds by shells or rockets which spread reagents or aerosol in clouds | Ί ,2j.

1 00 1 It is known an anti-hail protection method with (including) an active effect (impact) on hail clouds by significant (powerful) shock waves directed upwardly to the sky | 3-5 | . It is believed that the succession of shock waves transports positive ions from ground level to cloud level which disrupt formation of hail nuclei. This method of anti-hail protection is ful filled by the following way. Supersonic and significant shock waves is generated by sequential (serial ) detonating an explosive mixture of combustible gas (combusti ble Tuel) and air in a combustion chamber (in an enclosed body) of a hail preventing sonic generator (an anti-hail shock wave generator) and is directed upwardly to the sky. By selecting material and quantity of the combustible fuel, number and duration of detonations it is possible to provide signi ficant shock waves and to effect on the hail clouds up to 1 0km of altitude, changing hail cloud structure, preventing further development of hail and transforming hail to (into) rain, to wet sno or to small ice drops. As the fuel or combustible gas may be used acetylene gas, a mixture of propane- butane gases or other gas or liquid fuel with high energy capabilities [3-5 j. The explosive mixture of injected into the combustion chamber combustible gas and air is detonated by an inside located igniter in accordance wi th external command signals incoming from a control ler (a control means). These command signals are created in the control ler by an assisting (service ) operator (stal ^' O manual ly or remotely by means of cell phone GSM system, by radio aids (by radio technical devices), by means of radio communication, by means of telephone communication, or by other technical means of communication.

[0004] It is known as well an anti-hail protection method when simultaneously with the injecting

of the combustible gas a reagent (argentum iodide, for instance) is injected into the combustion chamber and is mixed with the explosive mixture of combustible gas and air [6,7]. Coming up small particles of the burned reagent immediately (directly) effect on the process of hail forming in addition to the shock waves impact [6,7].

[00051 Known anti-hail protection methods have some limitations (disadvantages) related to the absence of automatic operation and self-management (self-controlling) capabilities. Known anti-hail protection methods are operated only when corresponding commands come from the assisting (service) operator (staff), which includes subjective factor, or when corresponding commands came from an anti-hail radar station (which is a very expensive one), which is not always possible to get (to receive), or is not always contained (included) correct (real) information about hail situation and stage regarding protected (considered or specified) area.

[0006] Current anti-hail protection method [4], which is more fit (match) to the present invention, comprises generation supersonic and significant shock waves by sequential (serial) detonating an explosive mixture of combustible gas (combustible fuel) and air in a combustion chamber (in an enclosed body) of the hail preventing sonic generator (the anti-hail shock wave generator) and direction generated shock waves upwardly to the sky, injecting the combustible gas into the combustion chamber of the hail preventing sonic generator and detonating explosive mixture of the combustible gas and air in the combustion chamber of the hail preventing sonic generator by an inside located igniter, the injecting of the combustible gas and the detonating of the explosive mixture are performed in accordance with external command signals incoming from a controller (a control means), wherein the external command signals are created in the controller by an assisting (service) operator (staff) manually or remotely by means of cell phone GSM system [3, or 4,5] .

[0007] Current anti-hail protection method's disadvantage is its low operation efficiency due to the absence of automatic operation and self-management (self-controlling) capabilities.

[0008] Current anti-hail protection system [4], which is more fit to the present invention, comprises a hail preventing sonic generator for generation of a shock wave by detonating an explosive mixture of combustible gas (a combustible fuel) and air in a combustion chamber of the hail preventing sonic generator and direction of said generated shock wave resulting from the explosion upwardly to the sky, a fuel supply system (fuel injection means) for supplying fuel to the hail preventing sonic generator, located inside or outside the combustion chamber an ignition means, located inside (in) the combustion chamber an igniter for igniting the fuel in the combustion chamber, a control means for creating command signals of operation of the hail preventing sonic generator, for controlling the fuel supplying and the fuel injecting into the combustion chamber and for the igniting the fuel in the combustion chamber, a power supply, and a remote control system for remote controlling of the control means by means of cell phone GSM system. The hail preventing sonic generator comprises a cylindrical combustion chamber having a neck (a joint tube) with an upper orifice, a conical barrel, a fuel injector for injecting the combustible fuel into the combustion chamber and air inlet ports with flaps, which are seated in the' ports and open inwardly to provide one way valves for air rushing into the combustion chamber after each ignition. The conical barrel has a small diameter lower end connected to the upper orifice of the neck and a large diameter upper end. The fuel supply system includes a fuel reservoir, a mechanical valve, a solenoid valve, and a pressure regulator.

[0009 J Known anti-hail protection systems have some limitations (disadvantages) related to the absence of automatic operation and self-management (self-controlling) capabilities and require permanent staff of operators for direct or remote control of the anti-hail protection system.

( 00101 An object of the present invention is to enhance operation efficiency of the anti-hail protection system and to automate its exploitation.

General Description of the Invention

1001 1] The present invention proposes to overcome the limitation of the prior art with an anti hail protection method as claimed in claims 1 (or ) -4) and with an anti-hail protection system as claimed in claim 5 (or 5- 15). The anti-hail protection method is altered and the anti-hail protection system is configured for automatic detection of hail clouds by estimation of sky brightness temperature (by measuring the power of sky proper radio thermal emission) and for realization automatic operation and self management capabilities for the anti-hail protection system.

[00121 The anti-hail protection method according to the invention comprises: a) receiving signals of sky proper radio thermal emission;

b) squaring of the received signals of sky proper radio thermal emission;

c) accumulation of the sciuared signals;

d) comparison of the accumulated signals with N thresholds;

e) outputting (transferring) "one" (" 1 ") signal to a corresponding output of any of N thresholds if its input signal exceed the respective threshold, and a "zero" (naught, "0") signal otherwise;

f) considering jointly a set of the output (transferred) "one" and "zero" signals as a binary number in a binary code and creating (generation) a binary number code- signal corresponding to the binary number;

g) generation a warning (alert) code-signal in accordance with the binary number code- signal;

h) transferring by (through, via) electrical cords the warning code-signal to a controller (a control means) of a hail preventing sonic generator (an anti-hail shock wave generator);

i) setting by (in) the controller an operation mode of the hail preventing sonic generator, such as a switching-on mode, a waiting mode, an operating mode and a turning-off mode, in accordance with received by the controller the transferred warning code-signal, wherein the operating mode is set when the transferred to (received by) the controller the warning code-signal has value " " and more, the waiting mode is set when the transferred to (received by) the controller the warning code-signal has value "0", the turning-off mode is set when the transferred to (received by) the controller the warning code-signal gets upper-range (maximum) value of the binary number results when to any of the outputs of the N thresholds is outputted the "one" signal, and the switching-on mode is set when after the turning- off mode the next "0" value warning code-signal comes (is transferred) to the controller, the number N is defined on the basis of technical capabilities of the hail preventing sonic generator;

j) setting by (in) the controller operation parameters of the hail preventing sonic generator, such as power and duration of detonations, number of detonations and a detonation window, in accordance with the received by the controller the transferred warning code-signal;

k) generation command (control) signals by (in) the controller in accordance with the set mode of operation and the set operation parameters of the hail preventing sonic generator; and

1) generation supersonic and significant shock waves by sequential (serial) detonating an explosive mixture of preliminary injected combustible gas (combustible fuel) and air in a combustion chamber (in an enclosed body) of the hail preventing sonic generator and direction the shock waves upwardly to the sky, wherein the preliminary injection (injecting) before each detonating of the combustible gas into the combustion chamber and the detonating of the explosive mixture of the preliminary injected combustible gas and air in the combustion chamber by an inside located igniter are performed in accordance with the command signals incoming from the controller (a control means), the command signals corresponding to the operating mode of operation trigger the hail preventing sonic generator, the waiting mode of operation keeps the hail preventing sonic generator in operational readiness, the turning-off mode of operation interrupts the detonations and switchs off the hail preventing sonic generator, the switching-on mode of operation switchs on the hail preventing sonic generator and sets the waiting mode of operation for the hail preventing sonic generator.

m) Besides, the receiving of signals of sky proper radio thermal emission may be fulfilled (performed) at any distance far from the hail preventing sonic generator, at (under) any elevation angle of sensing, at any allowed central radio frequency from L to W-band of microwave, at any interference (noise) free bandwidth of receiving (reception), and at any polarization of sensing.

n) Besides, the anti-hail protection method comprises injecting a reagent together with the combustible gas into the combustion chamber and mixing the reagent with the combustible gas before the combustible gas detonating.

o) Besides, the warning code-signal is transmitted to and is received by the controller remotely by means of cell phone GSM system, by radio aids (by radio technical devices), by means of radio communication, by means of telephone communication, or by other technical means of communication.

The anti-hail protection system according to the invention comprises:

a) a hail preventing sonic generator (an anti-hail shock wave generator) for generation of a shock wave by detonating an explosive mixture of combustible gas (combustible fuel) and air in an enclosed body and direction of the generated shock wave resulting from the explosion upwardly to the sky;

b) a fuel supply system (fuel injection means) for injecting the combustible fuel to the hail preventing sonic generator, the fuel supply system being in communication with said hail preventing sonic generator;

c) an ignition means (a high voltage generator) for generation of high voltage spike (step, potential) for igniting the combustible fuel in the hail preventing sonic generator;

d) a control means for creating command signals for the hail preventing sonic generator operation, for controlling the combustible fuel supplying into the hail preventing sonic generator and the supplied combustible fuel igniting in the hail preventing sonic generator, the control means being in electrical communication with the fuel supply

system and with the ignition means;

e) a power supply, the power supply being in electrical communication with the control means and with the ignition means; and

a) a detector-warner (detector-alerter), for hail detection and warning (alert) signals creation for controlling the control means, the detector-warner being in electrical communication with the control means and with the power supply.

b) Besides, the hail preventing sonic generator includes a cylindrical combustion chamber having a neck with an upper orifice, and air inlet ports provided with flaps, which are seated in the air ports and open inwardly to provide one way valves for air rushing into the combustion chamber after each ignition, the air inlet ports area is larger of the upper orifice area of the neck, a conical barrel having a small diameter lower end connected to the upper orifice of the neck and a large diameter upper end, a fuel injector for injecting the combustible fuel into the combustion chamber of the hail preventing sonic generator, the fuel injector being in communication with the combustion chamber and with the fuel supply system, and being in electrical communication with the control means, and an igniter for sparking and igniting the explosive mixture of combustible gas (combustible fuel) and air, the igniter being located inside the combustion chamber and being in electrical communication with the ignition means, the ignition means being located inside or outside of the combustion chamber.

Besides, the fuel supply system includes a combustible fuel reservoir, a mechanical valve, the mechanical valve being in communication with the combustible fuel reservoir, a solenoid valve, the solenoid valve being in communication with the mechanical valve and being in electrical communication with the control means, and a pressure regulator (a pressure reducer), the pressure regulator being in communication with the solenoid valve and with the fuel injector.

Besides, the detector-warner includes an antenna, for receiving signals of sky proper radio thermal emission, a radiometric receiver for measuring a power of the receiving signals of sky proper radio thermal emission and estimating sky brightness (apparent) temperature, the radiometric receiver being in electrical communication with the antenna and with the power supply, a controlling compensation device (circuit), the controlling compensation device being in electrical communication with the radiometric receiver and with the power supply, a controlling multi-channel thresholder for hail detection, the controlling multi-channel thresholder being in electrical communication with the controlling compensation device and with the power supply, and a warning device for warning signals creation, the warning device being in electrical communication with the controlling multi-channel thresholder, with the control means and with the power supply.

Besides, the detector-warner includes a separate power supply for separate feeding of the detector-warner, the separate power supply being in electrical communication with the radiometric receiver, with the controlling compensation device (circuit), with the controlling multi-channel thresholder and with the warning device.

Besides, the receiving of the signals of sky proper radio thermal emission may be fulfilled at any distance away (far) from the hail preventing sonic generator, at (under) any elevation angle of sensing, at any allowed central radio frequency from L to W-band of microwave, at any interference (noise) free bandwidth of receiving (reception), and at any polarization o f sensing.

j) Besides, the anti-hail protection system comprises a remote control system for remote controlling of said control means by means of cell phone GSM system, by radio aids (by radio technical devices), by means of radio communication, by means of telephone communication, or by other technical means of communication, the remote control system being in electrical communication with the detector-warner, with the control means, with the power supply and with the separate power supply, the remote control system includes a transmitter for transmitting the created warning signals to the hail preventing sonic generator, the transmitter being in electrical communication with the warning device and being in electrical communication with the separate power supply, and a receiver for receiving the transmitted warning signals and transferring the received warning signals by (through, via) electrical cords to the control means, the receiver being in electrical communication with the control means and being in electrical communication with the power supply.

k) Besides, the anti-hail protection system comprises a reagent supply system for supplying the reagent to the hail preventing sonic generator, the reagent supply system being in communication with the hail preventing sonic generator.

1) Besides, the anti-hail protection system comprises a reagent injector-mixer for

injecting the supplied reagent into the combustion chamber and mixing the reagent with the combustible fuel before the combustible fuel igniting, the reagent injector- mixer being in communication with the combustion chamber and with the reagent supply system, and being in electrical communication with the control means, m) Besides, the reagent injecting system includes a reagent reservoir, a reagent mechanical valve being in communication with the reagent reservoir, a reagent solenoid valve being in communication with the reagent mechanical valve and being in electrical communication with the control means, and a reagent pressure regulator being in communication with the reagent solenoid valve, and with the reagent injector-mixer. [0014] Preferred aspects of the invention are defined in the dependent claims.

Brief Description of the Drawings

[0015] The invention will be better understood by way of the following detailed description of preferred embodiments, with reierence to the appended (accompanying) drawings in which :

Fig 1 is an outline of a first preferred embodiment of an anti-hail protection system;

Fig 2 is a detail block diagram of a preferred embodiment of a controlling multi-channel thresholder;

Fig 3 is a frequency diagram of a possible version of a controlling multi-channel thresholder thresholds maximum and minimum values.

Fig 4 is an outline of a second preferred embodiment of an anti-hail protection system with remote control facilities;

Fig 5 is an outline of a third preferred embodiment of an anti-hail protection system with reagent injecting facilities;

Fig 6 is an outline of a forth preferred embodiment of an anti-hail protection system with reagent injecting and remote control facilities.

Detailed Description of Pref erred Embodiments

[0016] Fig 1 gives an overview of a first preferred embodiment of an anti-hail protection system and shows the following high-level components and details thereof: a hail preventing sonic generator (9), a fuel supply system (10), an ignition means (12), a control means (1 1 ), a power supply (13), a detector-warner (detector-alerter) (20), an antenna (15), a radiometric receiver (16), a controlling compensation device (circuit) (17), a controlling multi-channel thresholder (18), a warning device (19), a cylindrical combustion chamber (1) which may comprise a substantially cylindrical body with a rounded bottom and a rounded top portion which leads into a neck (3). The bottom of combustion chamber (1) is solidly mounted to a concrete pad (34) by feet (8). One or more air inlet ports (5) are provided with flaps (not shown) which are seated in ports (5) and open inwardly to provide one way valves for air rushing into combustion chamber (1 ) after each ignition. Combustion chamber (1) is provided with a fuel injector (6) which may be located in or on the combustion chamber (1) and which may comprise a solenoid valve controlling flow of combustible gas from a combustible fuel reservoir (23) of a fuel supply system (10) through a mechanical valve (24), a solenoid valve (25) and a pressure regulator (a pressure reducer) (26) into a central portion of combustion chamber (1). An igniter (7) which may comprise spark gap electrodes and an ignition means (12) which may comprise a high voltage generator coil are provided for igniting the combustible fuel injected into combustion chamber (1) and which may be located inside or outside of combustion chamber (t). Solenoid valve (25), fuel injector (6) and ignition means (12) are controlled by control means (11 ). A conical barrel (2) has a large diameter upper end (35) and a small diameter lower end (36) which is connected to an upper ori fice (4) in neck (3) of combustion chamber (1).

[Ό017] Fig 2 shows the details of a possible embodiment of a controlling multi-channel thresholder (18) which includes N independent single level thresholders (SLT) with various threshold values.

[001 8 Fig 3 shows possible values of maximum and minimum threshold levels at various frequencies.

10019] Preferred modes of operation of the system of Fig 1 are now described with reference to Fig 1 -Fig 3. After initial starting (running) of the ant-hail protection system, that is after opening mechanical valve (24) and switching on power supply (13) which begins feed control means (1 1), ignition means (1.2) and detector-warner (detector-alerter) (20) the anti-hail protection system continues its operation automatically. Control means (1 1 ) opens solenoid valve (25) and sets hai l preventing sonic generator (9) in a waiting mode of operation. Flow of the combustible gas through open solenoid valve (25) and pressure regulator (pressure reducer) (26) comes to the input of closed fuel injector (6). Up-directed antenna (15) observes the sky, receives continually signals of sky proper radiothermal emission and transfers them to the input of radiometric receiver (16). Radiometric receiver (16) processes received signals and outputs (transfers) to the input of controlling compensation device (circuit) (17) a signal corresponding to a sum of powers of signals of external emissions (from sky, surrounding (ambient) and external interference) and internal noises. Compensation device (circuit) (17) compensates (reduces) a part of the incoming signals corresponding to clear air condition of sky observation and outputs remainder of the signals to the input of controlling multi-channel thresholder (18). In controlling multi-channel thresholder (18) the remainder of the signals is compared with N various threshold levels in N single level thresholders (SLT). Each single level thresholder (SLT) outputs "one" (" 1 ") signal to the corresponding input of warning device (19) if its input signal exceeds the respective threshold, and a "zero" (naught, "0") signal otherwise. Warning device (19) records (processes) jointly received "one" and "zero" signals as a binary number in a binary code, creates a binary number code-signal corresponding to the recorded binary number, generates a warning (alert) code-signal in accordance with the binary number code-signal and outputs (transfers) generated warning (alert) code-signal to the input of control means (11) by electrical cords. Control means (11) sets the operation mode of hail preventing sonic generator (9) in accordance with the received warning code-signal, such as a switching-on mode, a waiting mode, an operating mode and a turning-off mode, and sets operation parameters, such as power (the combustible fuel quantity) and duration of detonations, number (frequency) of detonations and a detonation window. Control means (11) keeps hail preventing sonic generator (9) in a waiting mode of operation if received warning code-signal has the value "0". When control means (11) receives a warning code-signal with the value " 1 " or more it sets the operating mode of operation, sets operation parameters of hail preventing sonic generator (9) in accordance with the value of the received warning code-signal, generates (creates) command (control) signals and runs (triggers, activates, starts) hail preventing sonic generator (9).

I ^" 00201 When hail preventing sonic generator (9) is operated, control means (11) causes combustible fuel to be released through fuel injector (6) into combustion chamber (1) until sufficient combustible gas for a full explosion resulting in a significant shock wave is present in combustion chamber (1). Mixing of the combustible fuel (combustible gas) with air in combustion chamber (1) is automatic and rapid. A short time a ter solenoid valve of fuel injector (6) is closed control means (11) triggers spark gap coil of ignition means (12) to create a high voltage pulse resulting in a spark across the electrodes of igniter (7). As the gas in combustion chamber (1 ) rapidly combusts, a shock wave results which is directed by conical barrel (2). The momentum of the combustion gases is directed upwardly, and once the combustion gases have fully expanded, the upward momentum of the gases causes a negative pressure to be created in the combustion chamber (1) which results in flaps of air inlet ports (5) being drawn open so that fresh air may be drawn from ambient through air inlet ports (5) to fill combustion chamber (1).

[0021 ] It is important to select a fuel and ignition system which can operate even when rain water (ice, snow) passes through conical barrel (2) into combustion chamber (1). It is important to select the parameters of combustible fuel, combustion chamber (1) volume to upper orifice (4) size as well as conical barrel (2) dimensions in order that a good shock wave is generated and sufficient aspiration through air inlet ports (5) takes place in order to bring in sufficient fresh air for the next combustion. [0022] When control means (11) receives the warning code-signal corresponding to the upper- range (maximum) value of the binary number P— results when "one" signal is

transferred to any (each) of N inputs of warning device (19) the control means (11) sets the turning-off mode of operation, switches off hail preventing sonic generator (9) and interrupts detonations that is stops fuel injection and ignition. Control means (11) switches on hail preventing sonic generator (9) and resets for hail preventing sonic generator (9) the waiting mode of operation when it receives from warning device (19) next (next in turn) signal with the value "0" only.

[0023] The number N is defined on the basis of technical capabilities and performance to change operation parameters of hail preventing sonic generator (9), such as power and number of detonations, repetition frequency of detonations or a detonation window.

[0024] Detector-warner (20) may be mounted at any distance (close, near, not so far, far) away from hail preventing sonic generator (9). Antenna (15) may be directed to the sky under any elevation (vertical) and azimuth angles. Preferable elevation angle is from the interval 0-30° from the vertical. When detector-warner (20) is mounted close (near) to hail preventing sonic generator (9) then more preferable interval for radiometric observation is 0- 10° from the vertical. Preferable azimuth direction for radiometric observation is the sector North West-North-North East, since it allows practically exclude the Sun direct influence on antenna at any time and at any season. For detector-warner (20) any kind of antenna may be used, e.g. horn, one mirror parabolic and hyperbolic, two mirrors (Cassegrainian) parabolic, dielectric, etc. with any beamwidth. Preferable antenna beamwidth is 10-20° at 3dB level. Radiometric receiver (16) may operate at any allowed central radio frequency from L to W-band of microwave (L, S, C, X, Ku, K, Ka, W), at any interference (noise) free bandwidth of receiving (reception) and at any polarization of sensing. Preferable bands for operation are X, Ku, K and Ka. For detector-warner (20) any type radiometric receiver may be used, such as a radiometer with a direct amplification, a superheterodyne radiometer, a noise-compensated (direct) radiometer, a Dick radiometer, a correlation radiometer, a crystal (detector) radiometer, etc. For radiometric receiver (16) preferred integration time is 1 -5 second and preferred sensitivity is 01 -05K in dependence on frequency band. 10025 1 When detector-warner (20) is mounted far (away) from hail preventing sonic generator (9) then it is preferable to control hail preventing sonic generator (9) remotely and transfer warning (alert) code-signals generated by warning device (19) to control means (11) by means of cell phone GSM system, by radio aids (by radio technical devices), by means of radio communication, by

means of telephone communication, or by other technical means of communication.

[0026] Fig 4 gives an overview of an alternative preferred embodiment of an anti-hail protection system which is controlled remotely. For sake of conciseness, only the differences with respect to the embodiment of Fig 1 are discussed below. Fig 4 shows in addition the following high-level components and details thereof: a remote control system (14), a transmitter (a transmitting phone) (21) for transmitting created warning signals, a receiver (a receiving phone) (22) for receiving transmitted warning signals and transferring received warning signals by (through, via) electrical cords to control means (11), and a separate power supply (27).

[0027] If there is not a possibility to use electrical network -1 10V or -220V as a basic electrical source for power supply (13) and for separate power supply (27) then a preferred embodiment for both power supply (13) and separate power supply (27) is 12V or 24V DC rechargeable solar battery with a solar power panel.

[ 0028] When detector-warner (20) is located far (away) from hail preventing sonic generator (9) its antenna (15) should be directed under the elevation angle providing a footprint at ~3.5km altitude just above protected agricultural area.

[0029] Fig 5 and Fig 6 show third and forth preferred embodiments of an anti-hail protection system with reagent injecting facilities in respect to the embodiments of Fig I and Fig 4. For sake of conciseness, only the differences with respect to the embodiments of Fig. 1 and Fig.4 are discussed below. Fig 5 and Fig 6 show in addition the following high-level components and details thereof: a reagent supply system (33), a reagent reservoir (28), a reagent mechanical valve (29), a reagent solenoid valve (30), a reagent pressure regulator (31) for providing required pressure for reagent injection, and a reagent injector-mixer (32) for injecting a reagent together with the combustible fuel into the combustion chamber (1) and mixing the reagent with the combustible fuel before the combustible fuel detonating. Reagent injector-mixer (32) which is control led by control means (11) may comprise a solenoid valve controlling flow of the reagent from a reagent reservoir (28) of reagent supply system (33) through reagent mechanical valve (28). reagent solenoid valve (29) and reagent pressure regulator (30) into a central portion of combustion chamber (1). Reagent mechanical valve (29) is opened together with mechanical valve (24). Reagent injector-mixer (30) is

opened and is closed by control means (11) simultaneously with fuel injector or so.

[0030] Detector- warner (20) should be mounted or it is necessary to mount detector- warner

(20)

under a convex radiolucent protective apron (shed, canopy, hovel) or/and to cover antenna (15) by radiolucent protective layer to prevent ice and liquid accumulation in front of antenna (15) and to protect antenna (15) and radiometric receiver (16) from direct influence of dust, precipitation, e.g. rain, snow, hail, etc,. If the protective apron is constructed from a non-transparent or partially transparent material, then the apron should not cover (cut) the beam (the main lobe) of antenna (15).

[003 1 ] Threshold levels of controlling multi-channel thresholder (18) depend on operation frequency (frequency band) of radiometric receiver (16). A curve of minimal threshold level ^' s frequency dependence of Fig 3 corresponds to a radiothermal contrast's frequency dependence of cumulonimbus clouds caused (generated) a rainfall with rare hail stones. Minimal values of radiothermal contrasts of Fig.3 were estimated and approximated from the results of multi- frequency and dual polarization (vertical and horizontal) radiometric measurements carried out under elevation angles 20° and 30° of sensing [8- 10] and from the known theory of passive (radiometric) remote sensing. Theoretical approximations show that these curves are acceptable for elevation angles from the interval 0-30° as well.

[0032] Maximal threshold level's frequency dependence of Fig 3 was estimated and approximated from the results of theoretical and experimental researches [ 10- 12] and corresponds to a radiothermal contrast' s frequency dependence of cumulonimbus clouds caused (generated) a hard hail storm which is impossible to prevent by any technical means.

[00331 Radiothermal contrasts of Fig 3 are given in Kelvin. Corresponding thresholds values in volts depend on structure and technical parameters of used (utilized) radiometric receiver (16) and may be defined from the results of theoretical estimations or from the results of experimental measurements and calibration. A preferable solution is to carry out preliminary calibration of radiometric receiver (16) in laboratory conditions or to carry out calibration of detector- warner (10) in field conditions. [0034] A threshold interval between maximal and minimal threshold levels of Fig 3 may be divided in N-1 parts, where the dividing by 2 or 4 or 8 or 16, etc. parts that is when N-3 or 5 or 9 or 17 etc. is preferable. In dependence on application features (conditions) of the present method and system of anti-hail protection the values of maximal and minimal threshold levels of fig 3 may be changed. When the value of minimal threshold level of Fig 3 is decreased then hail detection probability and false alarm are increased simultaneously. Taking into account a low exploitation expenditures (low price of combustible fuel) of hail preventing sonic generator (9)

[5 1 , it is possible to agree with high false alarm probability and to decrease the minimal threshold level of Fig 3 by 3-

1 5K in dependence on operation frequency of radiometric receiver (16).

10035 J It is possible to save material resources and to decrease exploitation expenditures of hail

preventing sonic generator (9) by decreasing the values of maximal threshold levels of Fig 3 which will cause increasing of a target (hail storm) drop-out probability.

| 0036 ] Maximal and minimal threshold levels may be corrected and may be changed individually during the exploitation of anti-hail protection system by controlling multi-channel thresholder (18).

[0037] Detail descriptions of structural, technical, operational and application features of hail preventing sonic generator (9) are presented in [3-5,7 1 . Although, in [4] is mentioned that for more efficiency the air inlet ports (5) area should be at least 1 .2 times larger of the upper orifice (4) area of the neck (3) and the igniter (7) should be placed in the geometrical center of the combustion chamber (1), the ratio of areas of upper ori fice (4) of neck (3) and air inlet ports (5) and the place of location of igniter (7) may be varied in dependence on geographical and climatological conditions of the location (position) of anti-hail protection system.

[0038] Detail descriptions of operational and application features of reagent supply system (33) and reagent injector-mixer (32) are presented in | 7 |.

[0030] Types and applications of remote control system (14) are presented and are discussed in P-7] .

[0039] Methods and realizations of hail preventing sonic generator's (9) automatic switching off at alert conditions and possible methods of organization of security of anti-hail protection system work territory o f (from) external attacks or encroachments are discussed in detail in [7 |. [0040] The hail preventing sonic generator's impact area is limited in a size and usually is about 500-600m in a radius over the generator [1 -7]. Therefore, the hail preventing sonic generator is mounted (is built) near protected agricultural fields and lands and is set in its waiting mode of operation after clari ication of the value of a compensation signal of controlling compensation device (circuit) (17). The value of the compensation signal for hail preventing sonic generator (9) work area is defined experimentally for each protected area individually by averaging the results of measurements of clear sky brightness temperatures (more exact antenna or apparent temperatures) carried out during days and nights under (for, at) various ambient (near surface) air temperatures 10-30°.

Reference

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2. Patent RU 1839961 , A01 G 15/00, 2006

3. Patent US 538 1955, E01 H 13/00, 1995

4. Patent AM 2505, KO I 1 1 13/00, 201 1 - a prototype

5. www. barva,am/ AM/Techno logy . html

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