公开(公告)号：US3611144A

公开(公告)日：1971-10-05

申请号：US3611144D

申请日：1969-03-03

Applicant: DATAMAX CORP

Inventor： HARMON SAMUEL T JR ,  ACKLEY JAMES R ,  MONROE KENNETH E

IPC: H04L27/02 ,  H04B1/68 ,  H03D1/22 ,  H04B1/30

CPC classification number: H04L27/02

Abstract: Digital or analog data to be transmitted is employed to amplitude modulate a carrier to generate a single-side-band signal which is provided to a receiver over a communication channel. At the receiver a signal having the frequency of the carrier component of the received signal and a constant phase with respect to the carrier component is derived by multiplying the incoming signal by both the output of a local oscillator and the oscillator output phase shifted by 90* and then comparing the two products to derive a feedback signal for adjusting the phase of the local oscillator. The oscillator output and the 90*shifted oscillator signal are each phase shifted by 45* and separately multiplied by the received signal and the output of the 90* multiplication is differentiated and summed with the other product to derive the original transmitted signal. In an alternate embodiment of the invention a double-side-band signal is detected by a pair of product multipliers having inputs which respectively lead and lag the carrier component of the received signal by 45* . The output of the product multiplier which has the 45* leading input is then differentiated and summed in a weighted manner with the output of the other multiplier to derive the original transmitted signal.