DE1269206B - Radio communication via artificial earth satellites - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CI .:

Number:
File number:
Registration date:
Display day:

H 04 b

German class: 21 a4 - 55

1269 206
P 12 69 206.7-35
February 7, 1961
May 30, 1968

The invention relates to an arrangement for establishing a communication link via artificial earth satellites using a common satellite search and tracking system, self-adjusting radar direction finder system working according to the scanning method, which is im Search operation with low focus and in pursuit operation with sharply bundled transmission and reception characteristics works.

It is known to use your own search radar device for the location of targets and after Finding the spatial coordinates of the target to transmit its further location to a tracking radar device. Such arrangements have the disadvantage that a great deal of effort is required for them and both devices must be well matched to one another.

It is Z. B. from the German patent 680 276, the search and tracking operation with a single antenna. With this anao order, however, the difficulty arises that with Switching from coarse bearing to fine bearing the target can be lost because it is by means of the coarse bearing cannot be determined so precisely that after the switchover it is still within the The detection range of the fine bearing. When switching from the coarse bearing to the field bearing If the target is lost, the coarse bearing process must be carried out again. For satellite transmissions but such an uncertainty is not permissible because that is required for a second bearing Time for message transmission would be missing.

The invention, which relates to an arrangement of the type mentioned at the outset, avoids this Difficulties due to the fact that the scanning during the transition from search mode to tracking mode is controlled in such a way that the working with low concentration and large stroke of the scanning movement Search characteristics by simultaneously reducing the stroke and tightening the Bundling is converted into a transmission and reception characteristic suitable for tracking operation.

Since, in the invention, the transmission from the coarse bearing to the fine bearing takes place gradually ensures that the target is not lost when switching from coarse to fine bearing, and it is also possible to carry out the direction finding process in the shortest possible time.

The invention and further details are explained in more detail with reference to drawings.

In Fig. 1 is a diagrammatic representation of the radio communication link
via artificial earth satellites

Applicant:

Siemens Aktiengesellschaft, Berlin and Munich, 8000 Munich 2, Wittelsbacherplatz 2

Named as inventor:
Dr.-Ing. Friedrich Baur, 8000 Munich;
Dr.-Ing. Karl-Ludwig Lenz, 8033 Krailling;
Dipl.-Ing. Gerhard Foeller, 8151 Söcking

Searching and tracking by a radar arrangement R shown, which is aimed at the satellite S above the earth's surface E by means of conical scanning movements. Conical scanning is known per se from radar technology and consists in the fact that a brush jet with an opening angle α moves on a cone surface with an opening angle β . The target direction is determined very precisely from the echo amplitudes at the individual beam positions.

In Fig. 2 an antenna arrangement suitable for this purpose is shown, in which a horn radiator H or other primary radiator for very short electromagnetic waves in the focal area of a parabolic mirror? is arranged. In order to achieve the conical scanning, the primary radiator moves in the focal plane on a circle around the focal point of the parabolic mirror. For searching, the primary radiator advantageously moves on a much larger circle, so that at a larger angle /? (Fig. 1) is searched. In order to cover the searched space without gaps, the distance between the mirror and the primary radiator can be changed mechanically or electrically so that the primary radiation center is no longer in the focal plane of the parabolic mirror. The focal point is denoted by F , and the focal plane passing through it is shown in dashed lines. This creates a brush jet with an enlarged opening angle Oi for the search movement. In this embodiment, the beam is broadened or narrowed by mechanical or electrical displacement of the radiator of the radar arrangement in the focal area of a mirror. The transition from searching with a broadened beam to tracking with a sharper beam becomes so expedient

809 557/164

made that the primary radiator slowly moves into the focal plane and at the same time the stroke of the Search movement is reduced. So it is the stroke of the scanning movement in search mode, i. H. with widened Beam, magnified and in tracking mode, d. H. when the beam is sharpened. at Generation of the scanning movement by pendulum or circular movement of the radiator of the radar arrangement At the focal point of a mirror, the emitter guides its movements with a large stroke during search operation out of focus, and when transitioning to tracking mode, it is simultaneously with the Moving the radiator into the focal point reduces the stroke.

The loss of antenna gain occurring at the same time as the beam broadening is in itself As is known, compensated for by increased transmission power. Since the search time is small compared to that The time that elapses during the satellite pass, i.e. during the tracking phase, is brief Sufficient power increase of the transmitter. When switching from search mode to tracking mode with increased beam sharpness, the transmission power again reduced to the level permissible for continuous operation. This is done in the radar array a circuit is provided that increases or decreases the transmitter power accordingly the change in the antenna gain during the transition from search mode to tracking mode and vice versa. The on- Actions required to search the satellite are also applied when the satellite is during its passage should have been lost due to erratic ionospheric influences. In order to this can take place at any time without loss of time, appropriate circuits are provided through which if the satellite is lost, the search process automatically starts and the tracking process after it is found is switched on.

Instead of the conical scanning, for the present purpose, the scanning from radar technology known monopulse technology can be used. With the monopulse technique there are two on each level uses antenna characteristics that diverge at a small angle. By amplitude or phase comparison of two of the received signals can be done after a single pulse transit time determine the exact direction from which the echo came back. If the location of the satellite changes continuously, the next measurement results in, i. H. at the next impulse, another one Deviation between antenna axis and satellite location. These measurements become control voltages derived, which track the antenna with a constant line of sight to the satellite. Here too the beam for the search process is expediently widened by removing the primary radiator from the focal plane a parabolic mirror can be moved out.

The conical scanning and the monopulse method are not related to use limited with the echo principle. Both principles can also be applied to direction finders. Such Recipients can be used to find and track an active communications satellite, a satellite that has a built-in transmitter. These recipients are also for that Searching and tracking of a satellite suitable, which is illuminated by a remote ground transmitter will.

Claims (4)

Patent claims: 1. Arrangement for establishing a communication link via artificial earth satellites using a self-adjusting, common for searching and tracking of satellites according to the scanning method working radar direction finder, which in search mode with low focus and in tracking mode works with sharply bundled transmission and reception characteristics, characterized in that that during the transition from the search mode to the tracking mode, the scanning is controlled in such a way that that with low concentration and large stroke of the scanning movement working search characteristic by simultaneously resulting reduction of the stroke and tightening of the bundling into a transmission and reception characteristic suitable for tracking operation is convicted. 2. Radio communication link according spoke 1, characterized in that the beam broadening or sharpening takes place by mechanical or electrical displacement of the radiator of the radar arrangement at the focal point of a mirror. 3. Radio communication link according to claims 1 and 2, characterized in that when generating the scanning movement by pendulum or circular movement of the radiator of the radar arrangement in search mode the radiator executes its movements with a large stroke outside the mirror focal point and in transition on tracking operation at the same time as moving the spotlight into the focal point of the Stroke is reduced and vice versa. 4. Radio communication link according to one of claims 1 to 3, characterized in that a circuit is provided which increases or decreases the transmitter power at the same time the radar arrangement according to the change in the antenna gain at the transition from search operation to pursuit operation and vice versa. Considered publications: German Patent Nos. 680 276, 1,036,941; U.S. Patent No. 2,907,030; "ETZ" magazine, issue A, June 1, 1958, pp. 375 to 382; Proceedings of the IRE, March 1959, p. 380. 1 sheet of drawings 809 557/164 5.68 © Bundesdruckerei Berlin