Abstract: The present invention discusses a modulation method and apparatus for modulating an extended-cavity laser (211). The method and apparatus (200-203) entails the use of each pulse in an input modulating pulse train as the trigger for the generation of a brief or “notch” pulse, i.e. a pulse that briefly diminishes the normal drive current. Each “notch” pulse is used to drive the semiconduct (211) embedded in an extended cavity with a current that flows opposite to its normal drive current. This serves to diminish the inverted charge-carrier population essential to lasing action, so the laser output falls sharply in a form of amplitude modulation. The invention also discloses a simple, miniaturized means (372, 352, 312) of micropositioning, based on the differential rotation of nested conical plugs, that can serve to couple the semiconductor laser to the cavity.

Abstract: Disclosed is apparatus for continuous wideband tuning of lasers, along with means for relating such tuning to a reference wavelength, by maintaining any desired offset from that reference wavelength. Also disclosed are multichannel fiber optics communications networks employing the above means, said networks being self organizing in terms of the wavelengths of their channels.

Abstract: The range from which a collision avoidance system at an Own station can receive SSR interrogations and reply messages from Other stations, is extended by utilizing P2 pulses for timing TOA measurement in the event P1-P3 pulse pairs are unavailable from the scanning main beam or its side lobes. The amplitude of the P2 pulses in the SLS radiation pattern being greater than the P1-P3 side lobes of the main beam over an angular sector of about 60.degree. centered on the main beam can insure reception of P2 pulses at much greater ranges than P3 pulses contained in the main beam side lobes can be reliably received. Using P2 timing, interlaced Mode A and Mode C reply messages contained in a main beam burst reply sequence are separated into two "families" of TOAs, the Mode C (altitude) TOAs always being longer than the Mode A TOAs by 13 .mu.sec. A "true" TOA is obtained by subtracting an appropriate time period from the TOA of each family, from which identity, altitude and range information is readily derived.

Abstract: A virtual secondary surveillance radar (VSSR) of the type described in U.S. Pat. No. 4,115,771 can produce inaccurate or indeterminate range information for a transponder positioned on or near a line between the actual SSR and the VSSR, owing to unfavorable geometrical relationships. This can be avoided by receiving the SSR interrogation and reply signals at two or more separated locations and processing the signals to provide positional information at a display site. No radar transmissions other than those of the existing ATCRBS are required.

Abstract: There is disclosed a video processor, for use in a counter-countermeasure stem, to convert radar video signals into binary information, consisting of four parallel channels, the outputs of which are ORed to obtain a combined synthetic video signal. Two channels operate on video from a logarithmic detector to optimize sensitivity in the presence of jamming and to extract real target information. The third and fourth channels operate from the output of a wide band detector and can distinguish between swept noise pulses and true target signals.

Abstract: A virtual secondary surveillance radar (SSR) of the type described in U.S. Pat. No. 4,115,771 can produce inaccurate or indeterminate range information for a transponder positioned near or on a line between the actual SSR and the virtual SSR, owing to unfavorable geometrical relationships. When such condition occurs, the error or ambiquity is resolved by transmitting interrogations from the virtual SSR site toward the actual SSR. The time delay between transmission of an interrogation and reception of a reply to it is a direct measure of the range of the transponder from the virtual SSR.

Abstract: A position-finding collision avoidance system (CAS) at an Own station within the service areas of at least two identified SSRs at known locations derives differential azimuth (A), differential time of arrival (T), identity and altitude data regarding one or more transponder-equipped Other station from standard ATCRBS interrogations and replies. These data are used to compute the positions of Own and Other stations for display at the Own station.

Abstract: A position finding and collision avoidance system derives, at an Own station within the service area of an identified SSr at a known location, differential azimuth (A), differential time of arrival (T), identity and altitude data regarding any transponder-equipped Other station or stations within a predeterminable region surrounding Own station, from standard ATCRBS interrogations and replies. These data are used to compute the positions of Other stations for display at Own station.

Abstract: A simple active/passive proximity warning system for an Own station that uses differential time of arrival values, direct time of arrival values, and differential altitude values determined from 1030 MHz interrogations from ground-based SSRs and Own station and 1090 MHz transponder replies from Other stations to identify threats is disclosed. The invention combines a passive detection system and an active detection system into an integrated system that overcomes the limitations present when either type of system is used by itself. Generally speaking, the passive system identifies threats and produces a threat alert when the differential altitude value and the largest time of arrival value associated with an Other station are below predetermined values. A preferred embodiment of the active system monitors the environment for SSR density, classifies the environment into a plurality of "cases", and automatically selects in response thereto one of a plurality of control modes.

Abstract: A threat warning collision avoidance system at an Own station that produces pseudo range data, identity and, when available, differential altitude data from standard ATCRBS interrogations and Other station's replies, rejecting the identity and data from Other stations that are outside a proximity space surrounding Own station, and producing a threat alert signal and displaying the identity and associated data of any Other station entering said proximity space.

Abstract: Radiolocation, with respect to an Own station, of a transmitter-equipped Other station by triggering the transmitter to transmit identification messages in response to timing signals from a reference source such as an Omega transmitter, receiving the messages and the timing signals at the Own station and comparing them to obtain a line of position of the Other station.

Abstract: 1. A side lobe suppression device for use in a directional receiver system omprisingFirst means for receiving first RF signals and converting them to first IF signals;Second means for receiving second RF signals and converting them to second IF signals;First delay means connected to the second receiving means for delaying the second IF signals a predetermined time;Third means operatively connected to said first means and said first delay means for time sharing said first and second IF signals;Fourth means operatively connected to said third means for demodulating said first and second time-shared IF signals; andFifth means operatively connected to said fourth means for comparing one of said first and second demodulated signals with the other, said fifth means including means for inverting the demodulated signals carrying the same information as said delayed IF signals, and a second delaying means for delaying the other demodulated signals a predetermined amount.