Showing papers on "Secondary surveillance radar published in 1984"

Using Roll-Angle Measurements to Track Aicraft Maneuvers

Abstract: Present day radar trackers used for air traffic control purposes perform satisfactorily during straight-line flight, but their performance during maneuvers is sometimes degraded The introduction of the secondary surveillance radar mode S system makes transmission of several airborne measurements to the ground station possible This paper investigates the use of one such parameter, roll angle, to assist present trackers during maneuvers to achieve accuracies comparable to those achieved during straightline ine flight

Adaptive MTD digital processor for surveillance radar

Abstract: A digital MTD processor interposed between a coherent video detector and a signal extractor of a surveillance radar comprises a plurality of Doppler filters connected in parallel to the video-detector output, including a zero filter, working into respective modulus extractors connected by way of respective threshold circuits to a common OR gate Each threshold circuit includes a fixed-threshold comparator and an adaptive-threshold comparator with inputs connected in parallel to the output of the associated modulus extractor, either of these comparators being connectable to the OR gate via a switch controlled with the aid of a rain-clutter map so that the adaptive threshold is used only during exploration of regions with heavy rain A ground-clutter map, which can be updated on the basis of level measurements performed on the output of the zero filter, controls the selective loading of each Doppler filter with one of three preselected sets of weights depending on the intensity of the ground clutter in the region being explored Where ground clutter is heavy, the threshold circuit of the zero filter may be cut off from the OR gate Both the fixed and the adaptive thresholds can be incremented in response to a command from the signal extractor generated upon the occurrence of an excessive number of false alarms

An mtd digital processor for surveillance radar with a bank of doppler filters and system of thresholds both selectable and dependent on the interference

Abstract: Digital processor for surveillance radar, in particular for air traffic control, constitude by a set of transverse fitters which cover the unambiguous Doppler frequency interval with Doppler frequency response selectable for each filter in order to adapt the filtering to the interference characteristics produced by unwanted echoes (clutter). At the output of the filters there is the extraction of the modulus and the comparison with the detection threshold, possibly adaptive. The result is sent to the overall detection logic. The selectable filtering and the selectability between the fixed and adaptive threshold allow the limitations of fixed filtering to be overcome by optimizing the capability of detecting targets in various types of interference.

Drive device for a surveillance radar antenna

Abstract: The radar antenna (8) is driven directly, without a step-down transmission, by means of a synchronous or asynchronous motor (1), which is supplied from the supply network (2) via a frequency converter (3) whose rated frequency (fn) is preferably adjustable, the rotor of which motor has a central hollow shaft (7) whose bearings at the same time carry out the function of the bearing for the antenna drive, and through whose interior a stationary waveguide is passed. A rotary waveguide coupling is fitted at the upper end of the waveguide to provide a connection in radio-frequency terms between the stationary waveguide and the antenna, which is driven via the waveguide. The drive device according to the invention can be used, for example, in surveillance and reconnaisance radar antennas of small to medium size.

Collision avoidance system for aircraft

Abstract: A collision avoidance system for aircraft in which one aircraft is equipped with an interrogation station having a secondary surveillance radar. .[.Coarse.]. .Iadd.A .Iaddend.distance measurement is effected either by passive or active distance measurement or by both of them. If the detected distance lies within a certain limit, the output power and/or period of the interrogation signal of the secondary surveillance radar of the subject aircraft is altered .[.so as to effect fine distance measurement.].. This system can be applied without increasing interference against the existing secondary surveillance radar system by keeping the output power and period of interrogation signal in a minimum required extent. By the same reason the system can keep the interference at a small extent between proximate aircraft, each mounting this collision avoidance system.

Closely Spaced Independent Parallel Runway Simulation.

Abstract: : As an outgrowth of the recommendations of the Industry Task Force on Airport Capacity and Delay Reduction, a simulation of closely spaced independent parallel runway operations under instrument meteorological conditions was conducted at the National Aviation System (NAS) Simulation Support Facility (NSSF) of the Federal Aviation Administration Technical Center. The simulation was conducted to determine (1) the impact of reduced runway spacings on the air traffic controller's ability to detect and resolve potential conflicts, and (2) the surveillance sensor accuracy and update rates needed to support closer runway separation. The NSSF environment was configured to simulate a terminal radar control room conducting independent parallel runway operations. Sixteen full-performance-level field controllers with monitor controller experience participated in the simulation as monitor controllers; final and local control positions were manned by Technical Center controllers. Six experimental conditions were simulated involving 48 1-hour data gathering experimental runs conducted over a 4-week period. Results indicated safe operations can be conducted at 3,400 feet runway separation provided a surveillance radar of at least a 2-second update rate and 2-milliradin accuracy is used. Some increase in penetrations of the no transgression zone will likely result from this reduction. (Author).

Motor drive device for a surveillance radar antenna

Abstract: The radar antenna (10) is driven according to the invention by means of a synchronous motor (1) which is supplied from the power supply network (2) via a frequency converter (3). In contrast to known drive solutions by means of asynchronous motors, DC motors or stepping motors which are directly supplied from the network, the drive according to the invention results, in particular, in a simple control capability of the torque and speed in wide limits and simple positioning, so that the most varied requirements which are placed on the radar antenna drive with respect to the torque, the control properties and the positionining capabilities can be met. The antenna drive according to the invention can be used in very many different radar systems having mechanically driven surveillance antennas.

Inexpensive multipurpose airborne surveillance radar

Abstract: Airborne radar has now been in operation for over 40 years, and nose-mounted microwave equipment is fitted to the majority of civil passenger jets for the early detection and subsequent avoidance of severe storm centres. The ground-mapping and sea-search equipment described here provides a high-quality operator PPI display without the expense of either a special cosec2 aerial or a stabilised aerial platform. A novel feature is the provision of a permanent flight record on a low-cost audio tape recorder for subsequent playback on the ground or in the air. This may be used for debriefing or archival use without the inconvenience of airborne photography or the expense of carrying an airborne quality video tape recorder. Extensive results of maritime, sea pattern and terrain targets are reported.