Abstract: A method of apparatus for determining the rectangular coordinate direction angles of a source of radio signals received by a four arm log spiral antenna and then processed by a beam-forming network to simultaneously generate both sum and difference modes. The sum and difference IF signals are heterodyned to a sum IF signal .SIGMA. and a difference IF signal .DELTA.. The .SIGMA. and .DELTA. signals are combined in an IF network to provide three IF signals, namely .SIGMA.+.DELTA., .SIGMA.-j .DELTA. and j .SIGMA., which are thereafter amplitude limited by respective limiting amplifiers. The three limited signals are processed by two phase detectors, which generate voltages E.sub.x and E.sub.y corresponding respectively to the sine of the phase angles of the limited signals .SIGMA.+.DELTA. and .SIGMA.-j .DELTA. relative to the limited signal j .SIGMA.. Since each combination of the voltages E.sub.x and E.sub.

Abstract: A method and apparatus for eliminating the sidelobe ambiguity in the range esponse of an FM-CW radar. An FM-CW signal with a periodic modulation frequency is transmitted and reflected from a target, received and combined with a sample of the transmitted signal to provide a combination signal. A portion of this combination signal including a selected harmonic and next adjacent harmonic is amplified and mixed with reference signals comprising the selected harmonic and next adjacent harmonic to provide two separate difference signals. These signals are in turn low pass filtered and further mixed to provide a range response with a mainlobe of one polarity and all side lobes of an opposite polarity. The energy under the mainlobe is detected and integrated to provide a voltage signal. When this voltage signal reaches a preset threshold level a further signal is generated.