DE1246051B - Method for finding short-term incident electromagnetic waves, such as those that occur in thunderstorm lightning - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

GOIs

German El .: 21 a4 - 48/01

Number:
File number:
Registration date:
Lay-out day:

T26867IXd / 2ia4
22nd August 1964
3rd August 1967

The invention relates to a method for direction finding of briefly incident electromagnetic waves len, the energy of which lies in a wide frequency band. Such briefly incident electromagnetic Waves occur z. B: related to Thunderstorm lightning. A crossed directional antenna system comprising 360 ° azimuth is used for the bearing as well as an antenna with a pie chart.

For direction finding of thunderstorm lightning or other atmospheric disturbances it is known a rotating antenna system with two vertically crossed Loop antennas and a rod antenna for determining the sides to use. The output voltage of one loop antenna is fed to a "write amplifier" fed, while the input voltage of the other loop antenna to a so-called Blocking amplifier is supplied. This ensures that the bearing system is only aimed at atmospheric Addresses disturbances coming in from the direction that of the respective position of the connected to the write amplifier. Antenna corresponds. A synchronous add The aerial rotation of the pen, moved over the recording paper, registers the atmospheric disturbances as points. Registration allows an overflow about the direction of incidence of the disturbances as a function of time. This known system is liable however, the essential part of it; that only a fraction the atmospheric disturbance is registered, since a registration only comes about if the antenna is aligned in the corresponding direction when the interference occurs. Also is with this known method an assessment of the amplitude size is practically hardly possible.

In another known thunderstorm direction finder, two vertically crossed fixed frame antennas and a rod antenna are used for side identification. The two frame lengths are routed through amplification channels that are the same according to bed day and phase and fed to the deflection system of a cathode ray display tube. The voltage of the rod antenna is used for brightness control. With this method, every atmospheric disturbance is registered on the screen as a line starting from the zero point, the direction of this line indicating the direction of incidence. On the other hand, when registering with the film stationary, only a reading of the azimuth of the thunderstorm is possible over a longer period of time. A measurement of the amplitude method for finding bearings for a short time
incident electromagnetic waves,
like them for example
occur during thunderstorm lightning

Applicant:
Telefunken

Patentverwertungsgesellschaft mb H.,
Ülm / bonäu, Elisabethensir ·. 3

Named as inventor:

Dr. deer nät. Hans Volland, Bonn;

Günter Heydt, Berlin

division for the individual flock is not doctrinal possible.

The determination of the original place of the ethereal Disturbance can be caused in the known method by simultaneously of two locations from the atmospheric disturbances. However, there is a constant communication link for the evaluation of the two stations necessary. In addition, the evaluation must be carried out separately for each individual atmospheric disturbance. As a result, the personnel expenditure when using such direction finding systems is very high.

The object on which the invention is based is to provide a direction finding method which can be designed such that once a statement about the spectral distribution of the amplitudes of the atmospheric disturbances and from the data obtained at one location the distance of the place of origin from the Peilört can be inferred.

According to the invention, the information about the direction of incidence is that of an atmospheric Disturbance resulting electromagnetic waves accustomed that with the over a crossed Directional antenna system and a rod antenna with a pie chart received short-term signals Resonance circles with the same resonance frequency are excited to natural oscillations; the initial fraud of the two resonance circles assigned to the loop antennas are in phase by 90 ° shifted against each other, and then the difference between the two phase-shifted voltages won; hereafter the difference becomes

709 619/246

between the phase of the differential voltage and the phase of that triggered by the antenna with pie chart Voltage measured and represented in the form of a direct voltage. This DC voltage represents a measure of the angle of incidence.

The direction finding method according to the invention will be explained in more detail using the exemplary embodiment in FIG. 1 will. There are two vertical frame antennas 1 and 2 as well as an antenna Kreischarakteristik'eine rod antenna 3 is provided. The output voltages of these three antennas result from the following equations:

Output voltage of one loop antenna

= C ₁

df

(D

Output voltage of the other loop antenna

(2)

= C ₁ - ^ - sin φ.

di

Output voltage of the rod antenna
u _z = C _z - g _(<) = Cs-Z ₀ - ö (*>

(3)

In these equations, 5 (t) means the time-dependent magnitude of the vector of the magnetic field strength of the atmospheric disturbance, S ^ the time-dependent magnitude of the vector of the electric field strength, Z ₀ the field resistance of free space = 120 πΩ, φ the angle between the frame plane of the x antenna and the direction of incidence of the atmospheric disturbance and C ₁ and C ₂ antenna constants. The voltages u _x , % and u _z are resonant circuits 4, 5 and 6 with a resonance frequency ω ₀ of z. B. 10 kHz supplied; at the exit of the resonance circles one receives after the decay of the atmospheric ones. Disturbance of the following voltages:

; Cos ψ ■ sin (GJ ₀ 1 + α) ■ e ^T ,

- C ₃

= - C ₄

I - sin φ ■ sin (<»" t + cc) ■ e ^T ,

sin

«) -E ^T ,

ρ)

The variables C ₃ and C ₄ take into account the resonant circuit data as well as the constants C ₁ and C ₂ and Z ₀ . T is the decay time constant of the oscillating circuits, which must be large compared to the duration of the atmospheric disturbance. The quantity g _{(o) 0} ) is the magnitude of the spectral amplitude of the atmospheric stoning at the angular frequency a> ₀ , oc is proportional to the phase of the spectral amplitude. The tensions Un _x and uuy are shifted in the links 7 and 8 by 90 ° against each other. The difference between these two voltages is then formed in element 9. The differential voltage u \ j is given by the following equation:

sin

The peak value of the voltage u _v is independent of the direction of incidence. In contrast, the phase of this voltage is directly influenced by the angle of incidence φ . After amplification and limitation in the limbs 10 and 11, the phase difference between the 'difference voltage U ₉ and originating from the oscillating circuit 4 voltage is then measured to. In the present case, this measurement is carried out with the aid of a flip-flop 12 with a subsequent low-pass filter or integrator 13. The output voltage Um of the integrator 13 is proportional to the

ίο angle of incidence φ. The angle of incidence is thus determined by measuring or displaying the direct voltage U _m .

If, in addition to the information about the direction of incidence, the spectral amplitude of the incident signals is also of interest, an arrangement according to FIG. 2 used. A rod antenna 14, which can be identical to the rod antenna 3, is provided, the output signal of which is passed through a low-pass filter 15 when it comes to finding atmospheric disturbances. This low-pass filter has the task of removing frequency components from z. B. hold back above 60 kHz to avoid the formation of image frequencies. The low-pass filter is followed by a mixer 16 with an associated oscillator 17 which varies, for example, in a frequency range from 85 to 130 kHz. can be. The output frequencies of the mixer stages move, provided that the intermediate frequency amplifier 18 connected has an input frequency of 80 kHz with a bandwidth of 250 Hz, between 5 and 50 kHz. The output signals of the intermediate frequency amplifier 18 are fed to a rectifier 19, the output DC voltage U _{0 of} which is a measure of the quantity \ g ( _m ) \ of the set receiving frequency.

In order to be able to display both values U _m and ΰ _ω together, the following display method is used according to a development of the invention: The voltage U _m , which represents a measure for the direction of incidence of the atmospheric disturbance, is used by one

+0 deflection system fed to a Braun tube, e.g. B. the Y- deflection system; furthermore the voltage is ύ _ω

■ fed to the Z-channel of the Braun tube, and it is also ensured that the electron beam is only brightly controlled when the voltage ύ _ω has a maximum due to a disturbance that is just present. A point of light is thus generated on the screen of the Braun tube, the vertical position of which indicates its direction of incidence and the horizontal position of which indicates its spectral amplitude.

When registering over a longer period of time, e.g. B. 5 or 10 minutes is the distribution of the spectral amplitudes as a function of the angle of incidence at the measurement frequency just set in Form of point clusters visible. These records can be captured photographically. The frequency dependence can be achieved by successive Measurements at different frequencies are examined. This is done using the frequency of the oscillator 17 set to different values. A clear assignment is also obtained with this training between direction of incidence and spectral distribution. In the F i g. 3 to 5 possible screens are shown, namely, these images were taken one after the other at different oscillator frequencies.

The point clusters on the left edge of the images, particularly in FIG. 3, are due to small atmospheric factors Disturbances. From these point clusters stand out in FIG. 3 five thunderstorms

Claims (3)

i 246, the spectral distribution of which can be clearly seen on the screen at the set frequency of 10 kHz. The screens of FIG. 4 and 5 were recorded at a set receiving frequency of 5 and 40 kHz. The thunderstorm distribution is the same as in FIG. 3. In the F i g. 4 and 5 only the strong herd can be seen. It has been shown that the following relationship applies when evaluating the registration: JV = JVoe "~ Λ (8) Here JV is the number of atmospheric disturbances that exceed a certain threshold S, JV0 is the total number of thunderstorms during the Measuring time emitted atmospheric disturbances; and A can be regarded as the product of a mean statistical spectral amplitude g0 and the transfer function of the waveguide earth-ionosphere. As a first approximation, A is a measure of the distance of the thunderstorm from the bearing location. To determine A and JV0, a The following method is proposed as a further development of the invention: The display as shown in FIGS For example, a directional antenna that only receives from the direction of a single thunderstorm, u nd feeds the received signals via threshold levels to counters, which count the atmospheric disturbances exceeding a threshold. It is even cheaper than using a directional antenna to use an amplitude discriminator for selection. With the appropriate setting, this only selects those disturbances for which the voltage Um lies within a certain interval that corresponds to the direction of the thunderstorm to be measured. Several values N are thus obtained, to which certain values S belong. If these values are entered in a coordinate system in which InJV is plotted on the ordinate and S on the abscissa, a straight line is obtained (FIG. 6). The intersection of this straight line with the JV co-ordinate gives the value JV0, that is to say the total number of atmospheric disturbances emitted by the thunderstorm in question during the measurement period. The number JV0 is a good measure of the activity of the thunderstorm. Λ is a measure of the slope of the straight line found. It can be determined from the graphic representation, which gives a statement about the distance of the thunderstorm source from the bearing location. As already said, the distance information obtained is only an approximation; at different frequencies one obtains different straight lines with different slopes which, however, intersect at point JV0. The fact that there are different slopes stems from the fact that the value A is not only dependent on the distance but also on the frequency. The values for A found at the various frequencies allow a statement to be made about the distance from the thunderstorm source, if one has previously assigned distance values to the various A values at the various frequencies with the help of another device that also allows distance measurement. A "calibration" is therefore necessary beforehand. Practical experience with the method according to the invention has shown that it is possible to locate thunderstorms at distances of a few 1000 km. The bearing accuracy achieved with the method according to the invention is approximately as good as the bearing accuracy of the known thunderstorm direction finder described above. It has also been shown that the distance error is around 15%. Claims 1. Procedure for bearing briefly incident electromagnetic waves, the energy of which lies in a wide frequency band, e.g. B. from Thunderstorm lightning, using a crossed directional antenna system comprising 360 ° azimuth and an antenna with a circular diagram, characterized in that with the Brief signals received via these antennas are resonance circles of the same resonance frequency are excited to natural oscillations that the output voltages of the two directional antennas assigned resonance circles are shifted in phase from one another by 90 °, and then the difference is formed from the two phase-shifted voltages and that then the difference between the phase of the differential voltage and the phase of the Antenna with pie diagram measured voltage triggered and shown in the form of a DC voltage which is a measure of the angle of incidence. 2. The method according to claim 1, characterized in that that the measurement of the phase difference and the generation of the dependent on the phase difference DC voltage brought about by a multivibrator with a downstream integrator is, whereby the flip-flop is in a stable position and due to the limited differential voltage into its other by the limited voltage triggered by the antenna with pie chart stable position is brought and the output voltage of the flip-flop between the two flip-flops is integrated. 3. The method according to claim 1 or 2, characterized characterized in that for additional measurement of the spectral amplitude of the briefly incident electromagnetic waves at the respective measuring frequency via an antenna with a circular characteristic received signals mixed with the voltage of a variable frequency oscillator, after the implementation are passed through a narrow-band filter and then rectified and that the direct voltage dependent on the angle of incidence and that of the spectral amplitude dependent DC voltage are displayed together. 4. The method according to claim 3, characterized in that the voltage u ₉ dependent on the Einfausrichtung is fed to one deflection system of a Braun tube and the direct voltage u _m dependent on the spectral amplitude is fed to the other deflection system of a Braun tube and that the electron beam of the Braun tube Tube is only light-controlled _{when the voltage m occurs.} 5. The method according spoke 3 or 4, characterized in that the 'size of the spectral Am- I 246 amplitude of the briefly incident electromagnetic Waves at different frequencies by setting different frequencies on the frequenzvariäbien Oscillator is measured. 6. The method according to any one of claims 3 to. 5, characterized; that after finding the Direction of incidence of the briefly incident electro-magnetic Waves finely determined for the place of origin the number JV of the incursions from this direction of incidence per time period depending on the incidence amplitude with the help of a threshold value step with an adjustable threshold S and a downstream counter for the purpose of determining the slope of the straight line resulting from plotting In N over 5 in a coordinate system and / or the one measure for the activity representing, is determined from the intersection of this straight line with the In jV coordinate resulting value N _a . 1 sheet of drawings 709 619/246 7.67 © Bundesdruckerei Berlin