Communications: directive radio wave systems and devices (e.g. – Air traffic control
Patent
1994-08-22
1996-03-05
Sotomayor, John B.
Communications: directive radio wave systems and devices (e.g.,
Air traffic control
342 29, G01S 1391, G01S 1393
Patent
active
054971578
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of monitoring an area with the aid of a frequency-modulated continuous-wave radar, and to a device for carrying out the method.
2. Background Information
The invention is especially suited for aircraft, e.g., airplanes, as onboard radar so that these can also land safely under unfavorable visibility conditions, i.e. low visibility aircraft landing, e.g., fog. Furthermore, under unfavorable visibility conditions during taxiing, a monitoring of the taxiway located ahead of an aircraft is also possible.
Such an onboard radar requires a small range, e.g., less than 5 km, and a relatively good resolution [sic], e.g., 1 m to 3 m in range direction or 0.1.degree. to 0.5.degree. in azimuth direction. For such applications, the use of a so-called pulse radar is known. This pulse radar has the following disadvantages, inter alia: required high ratio of range to range resolution, requires the use of a tube transmitter, e.g., a magnetron. This tube transmitter has drawbacks known per se, e.g., a short working life and a high maintenance expenditure (because of the high voltage to be produced); (transmitting) antenna gain may lead to injuries to health, especially to the eyes. Such a pulse radar is therefore unsuitable, especially for monitoring the taxiways and/or the apron of an airport; is, in a disadvantageous manner, very cost-intensive and therefore uneconomical; these in an unfavorable manner. These can only be avoided through cost-ineffective expenditure with regard to the EMC (electromagnetic compatibility).
SUMMARY OF THE INVENTION
It is therefore the object of the invention to propose a method of the generic type with which a monitoring of traffic routes on the ground, in particular landing runways and/or taxiways, becomes possible in a cost-effective and reliable manner. Furthermore, it is an object of the invention to propose a device for carrying out the method.
A first advantage of the invention is the fact that a frequency-modulated continuous-wave radar is used, which, in the following, is also referred to as FM-CW radar. Such a FM-CW radar only needs a low voltage for producing the transmitting power, e.g., 12 volts, so that economical and reliable electronic components , e.g., semiconductor circuits, can be used.
A second advantage is that for both the transmitting antenna and the receiving antenna, which may also both consist of a plurality of individual antennas, frequency-controlled antennas are used. In these, the main direction of the directional patterns depends on the frequency of the transmitting or receiving signal so that, advantageously, a mechanical swivelling and/or a generally expensive phase adjustment network for beam swivelling is not required.
A third advantage is that a very fast switch-over to different operating modes becomes possible, e.g., different ranges and/or different azimuthal scanning ranges.
Additional advantages emerge from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the invention is described in greater detail on the basis of embodiments with reference to schematically illustrated drawings.
FIG. 1 is a frequency/time plot showing a time-dependent transmitting frequency characteristic and the receiving frequency characteristic associated therewith;
FIG. 2a is a diagram illustrating the directional relationship of transmission and receiving lobes for a single transmitting antenna and a single receiving antenna which are offset (squinting antennas), and FIG. 2b shows the relationship corresponding to FIG. 2a for a single transmitting antenna and two individual receiving antennas;
FIG. 3 is a block diagram of an exemplary FM-CW radar according to an embodiment of the invention;
FIG. 4 shows a stair-shaped transmitting frequency characteristic for a step-by-step electronic beam swivelling;
FIG. 5 illustrates switch-over to different distance bands effected during the landing approach of an aircraft;
FIG. 6 is a block diagram of an arrangement ac
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Gruener Wilhelm
Liem Tiang-Gwan
Deutsche Aerospace AG
Sotomayor John B.
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