Method and apparatus for zero i.f. frequency and ionospheric pulse reception

摘要

1,047,887. Pulse radar; radio receiving systems. E.M.I.-COSSOR ELECTRONICS Ltd. June 25, 1963 [June 14, 1963], No. 25308/63. Headings H4D and H4L. A receiver, receiving a signal which includes pulses (pulse function F) of an oscillation having a predetermined mean frequency #/2#, wherein the phase (#t + #) of the oscillations as received may vary indeterminately with time, e.g. an ionospheric pulse sounding receiver or a communication receiver, comprises means 1 forming the product ¢akF[cos # - cos(2 #t+#) between the signal F 1 and a signal F 2 =a sin #t, from local oscillator 3 (which may form the transmitting oscillator in a pulse radar sounding system), filter means 8 extracting the low frequency term ¢akF.cos # from the product, this term being a series of pulses having amplitudes dependent on the phase of the received signal, and full wave rectifying means 5, operating on the low frequency term after amplification at 4, to produce a signal of one polarity, having, since the variations of # will be largely random over a period, an average value independent of # and dependent only on the amplitudes of the received pulses.