A method and apparatus for adjusting the modulation signal levels of overlapping beams which define along points of equal signal levels within the overlap a directional axis which in turn defines a desired navigation course for an airplane or similar maneuverable apparatus. At points offset from the directional axis, one or the other of the modulation signals will be greater in magnitude, depending on the direction of offset. The included angle between the two locus of points representing a predetermined difference in magnitude between the two modulating signals over the region between the landing field and the farthest reach of the beams defines the modulation course width for that particular difference in magnitude. In the illustrated embodiments, such a modulation course width may be effectively increased or decreased for a given antenna configuration and a given directional axis by altering the magnitudes of the modulation signals such that the difference in modulation levels is decreased or increased throughout the area of beam overlap. This is accomplished by introducing a portion of the modulation signal from one beam forming circuit into the other beam forming circuit, and viceversa, such that each radiated beam includes components of both modulation signals.
An indicator device for aiding a cyclist in locating a desired location for drafting another cyclist. The indicator device includes a support adapted for mounting the device against a bicycle, a vane having surfaces for alignment with the wind, the vane being pivotally mounted on the support, and a vane position orientation indicator. The vane orientation indicator being connected to the vane, so that the orientation of the vane relative to the bicycle is detected with reference to the vane orientation indicator.
Apparatus and method for use in instrument landing system (ILS) localizer and/or glide-slope receivers for deriving course deviation information are described. Specifically, a detected incoming ILS (localizer or glide-slope) signal is first filtered in order to extract appropriate 90 and 150 Hz navigation tones therefrom. Thereafter, two streams of timing pulses are generated; the first stream is phase-locked to the 90 Hz navigation tone and the second stream is phase-locked to the 150 Hz navigation tone. The peak amplitude of the 90 Hz navigation tone is sampled in response to the occurrence of a particular timing pulse occurring in the first pulse stream and the peak amplitude of the 150 Hz navigation tone is sampled in response to the occurrence of a particular timing pulse occurring in the second pulse stream. The sampled values of both navigation tones are then combined to obtain the difference therebetween which, in turn, is used to produce a signal which represents the actual localizer or glide-slope course deviation.
A phase reference navigation system and method employs a plurality of fixed narrow beamwidth antennas arranged to cover a predetermined angular sector and such that the patterns of adjacent antennas crossover one another at their half-power points. Each antenna radiates an RF carrier which is amplitude modulated by a reference phase signal and by one of two different frequency subcarriers. Adjacent antennas radiate different frequency subcarriers. Each subcarrier is frequency modulated by a variable phase signal which has a phase relative to the reference signal which corresponds to the direction of orientation of the antenna from which that subcarrier radiates. A receiver simultaneously receives the RF energy radiated by two adjacent antennas. Upon demodulation, the two variable phase signals are recovered and combined to produce a resultant signal which has a phase that varies as a function of angle between the two antennas. The invention utilizes FM capture effect principles to substantially reduce multipath effects and is useful for omni-directional, or bi-directional or uni-directional systems.
A method (for example, machine-implemented, e.g., via a receiver), for determining whether a transmitted pulsed-signal is a linear or non-linear frequency modulated (FM) signal, includes: iteratively determining upper and lower bound slopes associated with frequency components of a pulse of a signal during a time period of the pulse; and comparing each determined upper bound slope to a previous or initial upper bound reference slope and comparing each determined lower bound slope to a previous or initial lower bound reference slope in order to determine the linearity, or non-linearity, of the signal.
