A Circuit for Slecting and Amplifying without Turning Adjustment a Reduced Cappier in the Presence of Voice Sidebands and Noise

摘要

A serious disadvantage of reduced-carrier voice single-sideband communication for tactical military use is the necessity to tune the receiver very accurately to the frequency of an incoming carrier, in order to “exalt” that carrier and permit demodulation to take place. Owing to the frequency instability of presently-available radio equipment, the incoming carrier may appear anywhere in a band of uncertainty whose maximum width is not less than 200 cycles. The receiver must normally be set to the carrier frequency with an accuracy of the order of plus or minus ten cycles.