DE2359240C2 - Device for measuring visibility on the glide path of airports - Google Patents

Description

There are a number of devices designed for automatic 20. Then b is known to the atmospheric visual measurement, which according to the transmittome scatter coefficient in the visible spectral range, ter - or according to the scattered light principle, the norm of the scattered light devices, except for one measure reliably for the visual range. The device's characteristic systematic standard visual range V _n is a physical error in automatic devices; the mreukoefncient b is measured directly. about the relationship
Under favorable circumstances, she agrees with the

meteorologically determined by observers during the day .

see visibility well match. The standard visual range ^b = ^2π JPvP) *

or equivalent sizes can be obtained with transmittometers 30 °

or measured with scattered light devices. if

the atmosphere is always clouded evenly and the volume scatter function ß (<p) is the same

is lit, the installation site of the devices can be selected with the luminous intensity of the in the direction φ against the Prifrei. In fact, the atmospheric light has scattered light, which is often produced in the volume sphere but often great inhomogeneities in the opacity of the scattering medium, when exercised both in the temporal course and in the spatial volume of this volume with the unity of the illuminating distribution. Therefore, a more favorable intensification is illuminated. In order to get exact values for b , the equipment is of particular importance. must be obtained by a primary light source in

An automatic visual measuring method, which also provides the air generated and scattered in all directions, satisfactory information in such cases , requires scattered light from the entire angular range φ = 0 to be measured a considerable technical and financial 180 °. The curve of the spreading effort over the angle of 180 ° is heavily dependent

For aviation, among other things, the norm of the droplet size and distribution,
sees and the fire view (runway visual range) from technically it is not possible to the entire

Meaning. Under the standard view (visibility) the 45 scattering angle range from φ = 0 to 180 ° is recorded. meteorological visibility at the airport and there is already a possibility that

understood in its immediate vicinity. The rehearsal is to get visibility on the glide path (Runway visual range) is the fire view of voices. So-called backscatters are used for this purpose the runway. The standard visual range is therefore not used for devices that are not identical to the scattered light scream with the RVR, because with the latter an additional 50 over an angle of about 180 ° the visibility the brightness of the surroundings and the brightness of the landing measurements, but from a small, narrow reverse orbit light must be included in the calculation. Spread of about 3 °. This visual measurement results

These quantities are very imprecise values about the visibility range because of the so-called Allardian Formula linked and give that it does not solve the formula for normal viewing distance. Background brightness threshold. .. 55 When the backscatter devices have been recalibrated,

they usually measure the visibility quite accurately and are therefore a useful aid, especially

ρ _ Le ~ ^zN L these devices can be created inexpensively. the

N 2 ' but measurement accuracy decreases very sharply when in

6q more or less long intervals the droplets

Therein means the size and distribution of the scattered volume changes.

_ _. ,. , ". After all, by varying the intersection

Z - cxtinKtionsKoernzient, point of the measurement and transmission channel the backscatter

N _L = runway view (RVR), with backscattera also continuous along the glide path

L = light intensity of the lights. 65 measure so that measurements are made over the back

scatter on the glide path in a given

A practical problem at the moment is the measurement of angular range are possible
the visibility on the glide path of landing ma- The object on which the invention is based

3 4

consists in the standard visual range on the glide path light transmitter a light beam 2 in the direction of the glide more precisely and more correctly than with a back switch device sends out the path on which the landing aircraft is to measure and to determine the fire visual range. reached the touchdown point on the runway. the

To solve this problem, according to the invention, the optical axis of the measuring channel 3 is opposite to the optical axis Such electronic coupling of the backscatter 5 see the axis of the light beam 2 inclined. Measured Suggested device with the scattered light recorder, that is from the scattering volume 4 against the primary that an automatic calibration of the backscatter beam direction backscattered light. Next to the rates during the measurement in its immediate backscatter device 1 is a scattered light recorder 5 nearby within a measuring period mk the help of the installed. Both devices are electronic with each other Scattered light recorder takes place. io connected.

The difficulties arising from the fact that the backscatter device 1, after a calibration, delivers the backscatter device the measuring accuracy on the basis of sufficiently accurate measuring results. If the measuring principle cannot be changed, the result of the aerosol distribution will be poor because of the electronically coupled scattered light of this device. The scattered light recorder S recorder eliminates this is able to determine the droplet distribution, corrected via the electro-visual range, and the formula for Benic coupling the measurement results via a 15 but captures every change in the droplet size and angle of 120 ° in the scattered volume of the backscat calculation of the standard visual range V _n . The automatic calibration of the back makes the advantages of the two devices useful. Adapted aerosol distribution.
fen. The measured quantities thus obtained can also

The drawing shows an exemplary embodiment according to Allard's formula

of the invention shown schematically. over the theoretical fire visual range on the sliding

1 with a backscatter device is referred to, the 25 path.

1 sheet of drawings

Claims (1)

machines. This range of vision is considered by Foizik as a so-called Patent accepted “oblique standard visual range” has been referred to as a patent claim. {^ Yearbook 1959 of the WGL ₃ p. 230). This means that the device for measuring the standard visual range is the distance from the measuring height ζ B 30 or 60 _m and for determining the fire visual range on the 5 oblique to the ground lunab a scattered light measurement height measuring base was specified to be able to measure theoretically scribe geke η η ζ η etdurch calibrating a sight -Praktisch this is the coupling of such electronic backscatter formation of a device of this ^ m high, ie _{In the} apparatus with the scattering light pen, that a »Approach area of an airport, not feasible, automatic calibration of the backscatter device With the help of scattering devices, for example with a scattered light recorder in its immediate vicinity during the measurement, as described in the above-mentioned vicinity within a measurement period with the help of the ten reference, the standard -Scattered light pen takes place. visual range in good approximation according to the for- ^{15 mel} 3.91