| 摘要 |
A bearing indicating R.F. system comprising two spaced, broad-beam antennas supplying signals via power dividers to amplitude comparison means and phase comparison means, both operating without down-conversion to I.F. The main lobes of the radiation patterns of the antennas are inclined towards one another so that for non-normal incidence there is a difference between the amplitudes of signals received by the antennas. The amplitude comparison means comprises detector diodes, logarithmic amplifiers, and a first subtractor, the magnitude of the output signal (sensed with a threshold detector indicating which side of normal the radiation is incident. The phase comparison means comprises a hybrid ring having "sum" and "difference" output ports connected to an instantaneous frequency measuring apparatus and a detector diode, and further comprising logarithmic amplifiers and a second subtractor, the outputs of detector diodes in IFM being summed to provide a signal output connected to one amplifier. The output of the second subtractor is an accurate but ambiguous representation of the bearing angle with respect to normal (being an even function; the ambiguity can be resolved by reference to the output signal of the first subtractor which may also be used as an approximate representation of the bearing angle. Using broad-band R.F. components, the system may be operable over a broad bandwidth, e.g. an octave. A data comparator and a pulse repetition frequency filter control gates inhibiting the provision of bearing data except for pulsed incident radiation having desired frequency and PRF.
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