Radio DF method with frame aerials - uses sum and difference circuits and produces square wave outputs proportional to sine and cosine components

摘要

The direction-finding method uses a pair of loop of frame aerial fixed at 90 degrees to each other (1, 2). Their outputs are alternately switched to the input of a mixer (8). The switching frequency is double that of the timing generator (5). The output of an auxiliary antenna (3) is switched at the generator frequency by a polarity reversing switch (7) to the second input of the mixer. The mixer output product is amplified and switched at twice the timer frequency to demodulator inputs (11, 12). The demodulators are driven at generator frequency. - The demodulated signals are passed through filters and integrators (14, 15). The output of these circuits are square wave pulses which are proportional to the sine and consine of the angle of incidence of the received signal. The signals may be used to drive a cathode ray tube display