RADIO-INTERFEROMETER ANALOG PHASE-CHANNEL COMBINER (MOD II) FOR UNAMBIGUOUS SPACE ANGLE MEASUREMENTS IN THE NAVY SPACE SURVEILLANCE SYSTEM
NAVAL RESEARCH LAB WASHINGTON DC
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An electronic system called the MOD II phasechannel combiner is described, which automatically combines several noisy phase channels into one quiet channel, with two additional channels being available for vernier readout. The phase displacement for each channel is carried by a separate 1-kc signal. For combining purposes, each of these 1-kc signals is translated to a new frequency proportional to the interferometer baseline length, thus normalizing each of the phase channels. This is done by heterodyning the 1-kc signal with a set of reference frequencies derived from the precision oscillator in the station clock. The space angle solution is obtained by coincidence determination of the zero crossings of the above baseline frequencies. Pulses are generated at each zero crossing and monitored in an AND gate circuit. This circuit produces an output for the duration that the pulses from all the new baseline frequencies are in time coincidence. The time displacement of this coincidence pulse from a reference pulse is proportional to the sine of the space angle. This time displacement is detected and transformed into a dc voltage by an analog phase meter for presentation on a recorder, or it is digitalized and fed to a computer.
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