DE1268528B - Arrangement for the transmission of information between two stations - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Int. Cl .:

G08b

GERMAN

PATENT OFFICE

EDITORIAL

H 04 b
German class: 74 d- 8/02

Number: 1 268 528

File number: P 12 68 528.8-35

Filing date: July 6, 1966

Opening day: May 16, 1968

The invention relates to an arrangement for transmission of information between two stations (transmitter and receiver including optical antennas) by means of a modulated electromagnetic beam along one in a bad weather area transmission link located.

There have already been proposed and practically tested transmission arrangements, the modulated use coherent laser light. However, it has been found that a moisture content in the Atmosphere in the form of fog, haze, rain, snow or hail the energy of such rays absorbed and thereby the signal strength greatly reduced or a transmission via the individual makes transmission links impossible.

It is also known to use laser beams or other high-energy electromagnetic waves for this purpose use to convert atmospheric moisture into water vapor. The high required for this The energy of the rays and their wavelength makes the modulation of these rays for transmission purposes but difficult or impossible.

The invention is based on the object of creating a transmission arrangement for laser beams, by means of which the losses during the transmission as a result of bad weather conditions are reduced to a bearable one Measure to be reduced. The bandwidth ■ required to transmit the information at optical frequencies is intended to be maintained in all optical types of changing weather conditions will.

According to this invention, this object is achieved in that the arrangement at least one " additional source of high intensity electromagnetic radiation, e.g. B. of laser beams, and a device through which this additional high-intensity beam along the transmission path can be directed for the modulated beam which is used directly for message transmission and that the intensity of the additional electromagnetic beam is of such magnitude that at least substantial parts of the atmospheric moisture evaporate along the transmission path and the atmospheric attenuation caused by the moisture can be reduced.

It is known to have an arrangement for the transmission of information with modulated light with a source of high intensity electromagnetic rays, e.g. B. laser beams to provide and to direct this beam to a point along a predetermined transmission path. Through this However, as stated above, it does not become an arrangement for the transmission of information between two stations

Applicant:

International Standard Electric Corporation,

New York, N.Y. (V. St. A.)

Representative:

Dipl.-Ing. H. Ciaessen, patent attorney,

7000 Stuttgart, Rotebühlstr. 70

Named as inventor:
Dr. Armando Marzoli,
New York, NY (V. St. A.)

Claimed priority:

V. St. v. America of June 6, 1965 (469 495) -

reliable transmission in a bad weather area guaranteed. Only by the fact that an additional unmodulated electromagnetic beam is higher Intensity, which is not directly used for the transmission of messages, is intended to be flawless Message transmission through a bad weather zone with high attenuation enabled. This will namely achieved by evaporation of the atmospheric moisture in the bad weather zone a low-loss channel is created through which the message transmission directly serving modulated beam can carry out the transmission in a known manner.

Another feature of the invention is the selection of the wavelength of the electromagnetic Rays of high energy, which are expediently of such a size that the jet has a maximum Has absorption at atmospheric humidity. In contrast, the wavelength of the modulated The beam must be of such a size that it has minimal absorption in atmospheric humidity having.

In order to ensure reliable transmission, they are expedient in the arrangement according to the invention Switching and control means are provided which are the source of high intensity electromagnetic rays turn off when the transmission of the modulated beam is below a predetermined limit and switch on the radiation source if the transmission is above this value.

809 Mon I ■

The invention is explained in more detail in the drawing. In it shows

F i g. 1 is a schematic representation of the laser arrangement according to the invention in a block diagram,

1A shows a comparison of the cross section the high energy beam and the modulated beam,

F i g. 2 shows a schematic representation of the laser beam of the laser transmitter or the laser signal receiver in connection with an optical antenna,

F i g. 3 shows a graph of the dependence of the wavelength of the laser beam and the radius the drop of water in the mist,

F i g. 4 is a graphical representation of the relationship between the energy that is needed to about ₅ about 16 km to provide an aperture of about 0.565 cm ^2, and the horizontal ground visibility,

F i g. 5 shows a graph of the dependence between the frequency and the conductivity of Drops of water in the atmosphere.

In FIG. 1, a transmission of laser beams between stations A and B is shown schematically. The arrangement contains a transmitter that transmits information, as well as an optical antenna 1 at station A for the transmission of a modulated laser beam along a transmission channel to an optical antenna and a receiver 2 at station B. For the return transmission is a laser transmitter and an optical Antenna 3 is provided at station B which sends the beam to an optical antenna and a receiver 4 at station A. So far the arrangement for the transmission of the laser beam is known per se. However, if bad weather or unfavorable atmospheric conditions exist, the laser beam from either or both of the transmitters 1 and 3 is attenuated by the moisture content in the atmosphere to such an extent that the transmission is no longer reliable or between the stations .1 or B or vice versa is no longer possible.

In order to prevent this, the invention provides for a channel or a hole to be "bored" into the bad weather area between stations A and B using at least one high-energy laser beam. The laser source is shown in station A at 5. The beam is amplified and emitted by the optical antenna 6 along the transmission channel between stations A and B. The wavelength of the laser 5 is chosen so that the moisture absorption in the atmosphere has a maximum and the beam emitted by the antenna 6 has sufficient energy. to evaporate the moisture surrounding the laser beam.

In order to reduce the atmospheric attenuation in the bad weather area 18 and to support the penetration of the laser beam, a high-energy laser 7 and an optical antenna 8 are installed at station B, which are aligned with the laser 5 and the optical antenna 6. The opposing laser beams cause a zone of low attenuation in the bad weather area 18 and allow a transmission between the transmitter 3 and the receiver 4 from the station B to the station 4 and the transmitter 1 to the receiver 2 between the stations A and B.

In the case of the laser arrangement described, a known per se is connected to the output of the receivers 2 and 4 Control and switching device 9 and IO connected to perform demodulation when at as the atmospheric moisture content increases, the atmospheric attenuation increases. If that received signal at receivers 2 and 4 is below a predetermined threshold value which a reliable transmission is no longer possible. are controlled by the control devices 9 and 10 control switches 11 and 12 actuated, which switch on the laser sources 5 and 7. Through this arrangement an automatic switching is achieved in the sense that lasers 5 and 7 are switched on when unfavorable weather conditions cause a strong attenuation of the transmission laser beam.

The switches 12 and 12 can also be hand-operated Control switches can be configured by means of which the lasers 5 and 7 can be switched at will.

So that all the individual parts of the device according to FIG. 1 can be clearly shown is the Representation not chosen true to scale. The one for the emission of the beam of high energy and the one The equipment required for generating the modulated beam is in the transmission path arranged and not at an angle to it, as shown.

For practical operation, it is necessary that the laser beam modulated with the information 15 (Fig. IA) has a cross section that is larger than the cross section of the damping channel 16 caused by the bad weather it is achieved that at any time a part of the modulated laser beam passes through the zone of lower attenuation passes through. This has the advantage that small deviations of the beam between the transmitter and the associated recipient, which could result in the information not being created by the Canal 18 goes through, then avoided, when an extremely narrow carrier tape is used.

For the high energy laser beam, it is desirable that this is as narrow as possible. to reduce the energy required. The wavelength of the beam carrying the information must also be chosen so that that through the atmospheric Gases and water droplets took place at a minimum while the wavelength of the absorption occurred High energy laser beam must be in such a range. that the absorption of this beam through the atmosphere is at its maximum.

The physical processes involved in creating the low-loss channel 18 in the hatched areas indicated unfavorable weather zone 19 or when generating the area of lower atmospheric Attenuation play a role will be discussed later. Play in the formation of the channel Anyway, ionization and pressure effects play a role, which lead to the diameter of the channel becomes larger than the cross-section of the high-energy laser beam, so that a relatively wide channel is created, thereby reducing the interactions of atmospheric moisture on the laser carrier beam avoided or reduced.

In FIG. 2 shows an optical antenna, which has a lens 13 of small diameter, which is emitted by the arrangement 20 Absorbs light. The arrangement 20 can, for. B.

be formed by the lasers 5 and 7 or the laser transmitters 1 and 3. After the light beam has been guided to the focal point of the lens 13, the light of the diffraction image falls on the larger lens 14, which emits the light for the transmission essentially in parallel. The optical antenna is essentially an inverted telescope and has a gain of (ρ j. The gain of the optical antenna has the effect of reducing the output power of the transmitters 1 and 3 and the lasers 5 and 7.

The receivers 2 and 4 contain an optical antenna similar to that shown in FIG. 2 shown is similar. so that the radiation picked up by the lens 14 is collected and reduced by the lens 13 Diameter is recorded, from where it is focused on the input of the laser amplifier.

Different types of lasers can be used for the transmitters 1 and 3 and the high-power lasers 5 and 7 be e.g. B. Solid-state lasers, the ruby. Rare earths, containing trivalent uranium, also Gas lasers, the helium-neon. Noble gases and cesium diminishes, as well as semiconductor lasers, the gallium arsenite - Contains diodes, as well as fiber - cavity lasers and finally liquid and organic Laser.

Various modulation methods can be used for the laser transmitters 1 and 3, of which In particular, two prove to be reasonably favorable for solving the modulation problem of laser light beams have proven. One type is called "external modulation," which the light emerging from the source is treated independently of the operation of the source. These external modulation is achieved by applying the Pockel effect. Kerreffects. Faraday effect. the conductivity modulation and the supersonic pressure effects achieved. The second type of modulation is the so-called "Internal modulation" in which the laser source itself is subject to change will. The internal modulation can take the form of feedback control, which turns out to be very Has proven useful for controlling high power pulses and is equally applicable for the amplitude modulation of uniform waves. Zeeman and Stark modulation as well as geometric Variations.

The receivers 2 and 4 contain an active preamplifier or a passive filter a coherent Mixer stage or a video detector, an intermediate frequency or video amplifier and finally one second detector or a frequency discriminator or the like. A radiation converter is located in the receiver arranged, which converts the received radiation into electrical signals. Known types of such Radiation converters are particle transmitters that work with detectors that emit photons, such as z. B. Phototubes. Photomultiplier. Traveling field microwaves. Phototubes, photoconductive detectors and finally energy integrators or thermal detectors.

With the help of an automatic auxiliary and self-control system at stations A and B, the aim is to ensure that the laser transmission is maintained during unfavorable weather conditions. This is intended to ensure that the majority of the modulated beam transmitted by one station is received at the other station both in clear and in unfavorable weather.

Before looking at the physical processes in the channel created or when reducing the atmospheric Attenuation zone is discussed, briefly the most important properties of the atmospheric Water drops are explained.

Fresh distilled water has a relative dielectric constant of 80 and a conductivity of K) "·" ■ MHO m at 20 C with direct current and a very low frequency. At higher frequencies the relative dielectric constant becomes complex, with the imaginary part giving a measure of the absorption. The impurities present in the atmosphere are dust. Smoke and salt particles of various substances including solutions of gases such as carbon dioxide (CO ₂ ). Nitric oxide (NO ₂ ). Ozone (O,) and small traces of nitric acid (HNO ₁ ).

Nitric acid is the result of the oxidation of NO ₂ with O during electrical discharges in thunderstorms, whereby the conductivity of the water droplets is reduced to IO ³ MHOm. Due to the presence of atmospheric impurities, every drop of water in the atmosphere can be viewed as a dielectric matter in a high frequency field.

In the following considerations we take the laser beam as a uniform electromagnetic one High intensity field on. in which perfect spheres of matter are immersed. It should Each sphere has a complex relative dielectric constant that varies with frequency changes and in which the conductivity corresponds to the one shown in FIG. 5 is subject to changes. A part the energy is scattered depending on the frequency, while another part of the energy is through the molecules are absorbed. The maximum absorption is present at frequencies consistent with the Ionization of atmospheric conditions is in resonance and at a frequency at which the dielectric loss is greatest in the drops. The operation of the high intensity lasers 5 and 7 is best at a wavelength at which the scattering in relation to the molecular absorption is low. Wavelengths which are larger than the particle radius and which the dark windows in the Corresponding to the frequency spectrum, lasers 5 and 7 are the most favorable. At frequencies at which the absorption resonants are high, the molecular Absorption must be large enough to meet the ionization threshold of the atmospheric gases that due to the plasma effect, an attenuation around the laser beam must be exceeded. This will make the The initial temperature along the jet is increased, which lowers the conductivity of the water droplets will. The action of a strong electromagnetic wave on a dielectric sphere results in a strengthening of the field inside this sphere and a sudden increase in its temperature.

The first part of the energy consumed is in the

Drops stored until the evaporation threshold is reached. Every additional amount of energy caused by at this point an increase in the pressure on the environment (expansion effect). An enlargement The molecular energy consumption in the newly formed water droplets causes a kind of chain reaction. The initially narrow beam that the

Lasers 5 and 7 emitted is given a coat by hot water vapor, which in turn is surrounded by a cold aqueous atmosphere.

In order to consider how long this phenomenon lasts in a stagnant atmosphere, one must consider that the relaxation lines of the ionization are around 15 seconds for small ions and around 500 seconds for large ions. Since in reality the atmosphere is not stagnating, the channel is kept open by a continuous supply of energy in the form of repetitive pulses or a source of continuous energy. The penetration efficiency of the high-intensity rays from lasers 5 and 7 can be improved by using different frequencies, since the droplets in the atmosphere are of different sizes, mainly two or three main sizes. Fig. 3 shows the frequencies applicable to fog at which the scatter is less than 0.33 " ₀ from that in the visible range.

To get an idea of which The energy required for the penetration process in the case of fog will be the. the following ^ calculations carried out. :. '! , -

After the Lambertsehet! Law for monocromatic parallel light is the power in one DistanceX from source:

P _x =

. - ΒΛ "

(D

where · the power emitted by the optical antenna 6 or the optical antenna 8 is F ₀ and B is the total attenuation coefficient in the "hole" created in the atmosphere. B is usually the number of scattering and absorption coefficients. ·

From equation 1 it can be seen that the performance at the interface with the mist changes with distance. In the following, an average power between the transmitter and receiver is assumed ^ If the average power is denoted by P and the distance between the transmitter and receiver by R. then the following equation applies:

45

P =

P _o e- ^BX dX

P ₀

(2)

(3)

Fog boundary layer P is ₁₁ because the fog is pushed back by the jet.

The short-distance transmissions in which BR <: 1. the factor e " ^K can be replaced by a MacLaurin series, so that equation 3 has the following value:

ρ - ^ A.

BR

I «. + ψ]

When the fog is in the beam and or a longer distance between the transmitter and receiver has not evaporated. one can assume that equation 3 approaches the following value:

BR

The value

BR

acts as a kind of quality factor,

ie. the larger BR is, the larger P ₀ must be in order to achieve the same average power.

A general expression can now be derived for the value of the energy that is required to get a complete "hole" in the fog. Since a straight line transmission is taken as a basis the speed of propagation can be neglected and it can be assumed that the ray is currently established between the transmitter and receiver. The total energy of the beam is

E _n = Pf.

(10)

where P is the average power and f is the length of time for which the power source is switched on is. The following expression can be derived from equation 3:

E -

(1 -e

-flK,

f.

(Π)

However, not all of the energy is absorbed by the mist. One accepts. that an amount kE _B of the total energy is expended for the evaporation of the mist, then applies

0 <A- <1.

(12)

In the borderline case B-η Ό applies: lim P = Po dB ⁽¹ ~ ^{e ßR)} B -> R. ■ d (B)
DB = ■ O P ₀
R ~ 0 + R
". Γ

(4)

(5)

= P ₀ ■ '"■ -' (6)

This is the expected result relating to the ideal case in which the power on the It is important that in order to penetrate the fog, or in other words to form a zone of reduced atmospheric attenuation in the bad weather zone, the wavelength must be chosen that a maximum absorption point in the frequency spectrum is obtained (ie, k must be made as large as possible). For the transmission of the signals, the wavelength must be selected so that there is minimal absorption by the moisture in the atmosphere.

If M is used to denote the number of grams of water per unit volume of the mist, A the cross-section of the jet and α the amount of energy required to heat 1 g of water from 15.5 to 100 C and to evaporate this amount of water, this gives

is the value for the energy required to evaporate all the water in the jet as

E ' = aMAR.

(13)

If you express M in such a way that it reflects the horizontal view of the ground, the following must be taken into account:

M = 1.620 1 (Γ ³ V ~ ^u43 , (14)

where M is in grams per cubic centimeter and V is the view per 0.30 cm.

Substituting equation 14 into equation 13, one obtains

E - 1.620

(15)

where AR, the radiation volume, appears in units of square centimeters. If one now sets the total energy of the jet, which is required for the evaporation of the water, to be equal to E ', one obtains

20th

Kp ₁ BR

(1 - e ~ ^BR ) t = 1.620 · ΙΟ " ³ α ARV ~ ^iAi . (16)

Solved for P _o t , the energy required at the output of the optical antenna is obtained as

Pot-

1620

Jfe (1 -

^(I7)

If one sets α = 2.61 ΙΟ ³ watt seconds = 2.61 10 ³ joules, the conversion to centimeters results in:

P _o t -

6.8 IQ ⁵ ABR ²

² ν ¹ - ⁴ - ³

35

(18)

This amounts to:

P _o t - the required transmitter energy (watt-seconds or joules)

A = cross section of the beam (cm ² )

B = the damping coefficient (miles = 1.61km " ¹ )

R - distance between the transmitter and receiver (1.61 km)

V = the horizontal floor view (30 cm)

k = the proportion of the total radiation energy required for evaporation of the fog.

For the practical case that BR> 2 applies:

Pot =

6.8 ⁵

In the ideal case, in which B- * 0, the application of L'Hopital's rule in equation 19 results

60

lim pot

6.8 ⁵

ARV

-1Λ3

(20)

tion of visibility is shown. The following values are used here:

k A. B. R.

0.8,

0.0565CM ² ,
1.61 km " ¹ ,
16.1 km.

B - * 0.

65

Equation 19 is in FIG. 4, the required energy of the transmitter as a radio frequency. The cross-section 0.0565 cm ² represents the narrowest beam. For a ruby laser beam emitted from an optical antenna, the bandwidth is:

7-10

-4

20-2.54

= 1.4 microradians, (21)

15th

(19) therefore less than ³ / io arc seconds.

The area illuminated at a distance of approximately 16 km from the source would have a cross-section of 0.0565 cm ² , which is a reasonable approximation of reality for a parallel beam.

It should also be mentioned that the assumption here was that the fog was itself behaves statically, and the "hole" caused by the impulse of high energy remains. In reality however, as a result of the movement of the mist and other dynamic effects, it is necessary that the impulses of high energy recur continuously. The required repetition rate must be a function of the fog properties and be determined experimentally for the individual case. The continuous power that is theoretically required to make the "hole" with a horizontal wind to maintain a speed of one mile per hour is:

(W

where Q is the value of grams of water per second that passes horizontally through the jet. After that is

Q = MV ₀ A ', (23)

where M represents grams of water per cubic centimeter of fog, V _D represents the speed of the droplets (which is assumed to be equal to the wind speed) and A 'represents the cross section of the jet times the length of the path. If, in a practical embodiment, the bottom view = 150 m, path length = 16.1 km, cross section of the beam = 0.268 cm (corresponds to a cross section of 0.0565 cm ² ), wind speed = 1.61 km / h, the result is at M = 2.3 · 10 ~ ⁷

P = 11.5 kW.

From equations 9 and 12, assuming that k = 0.8 and B = 2 and P = P , we get:

^p ° ⁼ nr ^{= 143kw (23)}

as required transmission power, d. H. the power required at the output of the optical antenna. The above calculations were for a single high power laser and one on it coupled optical antenna and do not take into account an important point that is the

SW 549/117

11 12

required power 'depressed. It is namely light to be absorbed more strongly than a smaller number. B. in rain, snow or difference between the outer shell and the interior hail is the case. In the visible range, that of the "hole" and the ionization in the "hole" loss during the transmission in DB have a directly proportional effect to the effect that the formation of new water is opposed to the ratio of the transmission distance and horitrop in the hole in a zontal view. When the view becomes along a route. The 16 km of moisture flowing into the "hole" is about 300 m, the loss would therefore be less than the calculated question, from the transmitter to the receiver about 1000 DB, so that the required amount. Energy can be smaller. In unfavorable weather zones, the Miesche by far outperforms Rayleigh scattering. In the visible area and the optical antennas coupled to it, the scattering is independent of the required wavelength, approximately by a factor of 2. With a radius of the water power at the output of a single arrangement, drop of 5 μm, a typical radius with the result of the fog occurring in the optical antennas, the dispersion is essentially with wave power amplification, the actual power lengths of less than 10 μτηηι constant. The optical output on the laser is reduced by the amplification factor of the paint frequencies of the high-intensity laser beam, optical antennas. ·. which penetrates into the unfavorable weather zone, the approximate calculation of the required lie in the area in which the scattering is low and the power of the beam to create a "hole" the molecular absorption is high. In fog, rain, snow or other bad weather causes the drops to be distributed in such a way that these open areas can be performed in the same way as sequences in the far infrared area, as described above for the case of fog When the hole is formed «Effect ionization was carried out. The energy that is required to create and pressure effects an enlargement of the "hole", the first "hole", is then to be used to calculate the power and / or energy of the laser, if the power is calculated that can be reduced to the source: Maintaining the "hole" is necessary. At frequencies at which the absorption resonance case of rain is high, under the same assumptions as nances, the molecular absorption is at. Fog evident. = one _; very high . Power large enough to meet the threshold required for ionization to cross a complete "hole" in the rain of atmospheric gases, so that it can be kept open. In fact, in light rain 30 · a damping path along the power .in; the order of magnitude of 200 kW er laser beam is created. This has the effect conducive to a channel of 0.0565 cm ² temporarily from that the temperature km along the beam a distance of 16 to keep open. Conversely, it is higher and the conductivity of the water droplets to form the mist is lowered as a result of the properties. Due to the presence of atmodes rain, however, with the transmission of only moderate 35 spherical impurities, every drop of water can lose; in moderate rain, as a dielectric in a high-frequency field over a distance of 16 km, these are 42 DB and must therefore be considered. The transmission loss at Lavon bearable extent. In the case of rain and rays due to rain it is less than in case of fog. other types of adverse weather conditions, in the event of moderate rain, e.g. B. a precipitation z. B. snow or hail, it is therefore only necessary- 4 ° of 4 mm per hour, the entire loss along licit is to create a "partial hole". With the described distance of 16 "-Km about 42 DB. The radius arrangement is only necessary in which" the raindrop " is: to provide a" hole "in the order of magnitude of unfavorable weather layers 600 μm and the scattering at wavelengths below - and to maintain it, by means of which the transmission of the information takes place essentially constant over half a millimeter. 16 km near Washington a 1-watt transmitter, however, since the transmission losses in the rain do not experience a time loss of 0.4% due to rain, ie are as high as, for example, in fog, is also 35 hours per year. This invention reduces total downtime because the 50 can achieve the required power of the laser to the degree of degradation downtime a function arrangement can be reduced, which represents the power of the high-power laser. As has already been mentioned above, it should be pointed out again that with all of the arrangements described, two bad weather types, the vapor pressure, the extreme separate lasers for penetrating the bad differences in temperature between the outside 55 weather zone and for the transmission of the information jacket and the inside of the "hole" as well as the functions are necessary, since the high-power laser ionization inside cause moisture - at a point of maximum absorption in the frequency drop into the; Fall into the inside of the hole. Out of spectrum (dark window) have to work. ' during which the gain of the optical antenna affects the information broadcast at one frequency and the fact that two laser arrays must be high 60, in which the absorption of a minimum energy is provided, affects that is.

the power of the laser can be reduced. The use of a high power laser after

In the following the physical processes of the invention are the conventional frequency

the arrangement and its advantages briefly move together, since those frequencies that

to get nabbed. ⁶ 5 penetrate the fog, in the lower infrared range

Fog is the most unfavorable range (of the order of 100 µm) and

In case of bad weather, as this usually results in a considerable loss in bandwidth

There is a large number of small drops, which is in contrast to the bandwidth in the transmission

in clear weather. For example, if the transmitter works at 0.5 [jtmm in clear weather and at If the fog changes by 100 μm, there is a loss of 99.5% of the original bandwidth. In the arrangement according to the invention, however, the Always transmit information at the same frequency regardless of weather conditions, so that the bandwidth is retained.

To ensure strong reception, the information that comes through the "hole" in the Bad weather area is transmitted on a relatively wide beam. This will be Deviations through which the information could possibly miss the "hole", as is the case with a very narrow information carrier beam could be the case, avoided. That in the bad weather area The "hole" created by the high-power laser does not have to be a perfect cylinder, the directed parallel to the ground. Because of the density differences outside and inside, the information remain inside the "hole" in the bad weather area.

The separate high-power lasers at each end of the transmission path can be operated with With the help of known auxiliary control devices.

The vapor pressure, the differences in temperature between the outer jacket and the inside of the "hole" and the ionization inside prevent the new water formation that fills the inside could (as with rain and non-static fog). The inward pushing flow per unit of time will be less than the calculated value.

Claims (4)

Patent claims:, s 1. Arrangement for the transmission of information between two stations by means of a modulated electromagnetic beam along one located in a bad weather area Transmission link, characterized in that that the arrangement has at least one additional source (5, 7) for electromagnetic High intensity rays, e.g. B. of laser beams, and a device by which this additional high-intensity beam along the transmission path for the Message transmission directly serving, modulated beam can be directed, and that the intensity of the additional electromagnetic beam is of such a size that at least substantial Parts of the atmospheric moisture evaporate along the transmission path and the atmospheric attenuation caused by moisture can be reduced. 2. Arrangement according to claim 1, characterized in that the wavelength of the electromagnetic High intensity rays of such size are such that the ray has maximum absorption exhibits at atmospheric humidity. 3. Apparatus according to claim 1, characterized in that the wavelength of the modulated The beam is of such a size that it has minimal absorption of atmospheric humidity having. 4. Arrangement according to claim 1, characterized in that switching and control means are provided that turn off the source of high intensity electromagnetic rays when the transmission of the modulated beam is below a predetermined limit value and switch on the radiation source if the transmission is above this value. Considered publications:
"Funkschau", 1965, issue 8, pp. 187 to 190. For this purpose 2 sheets of drawings «09 549/117 5.6S O Bundesdruckerei Berlin