GB1086846A - Improvements in or relating to radio and like transmitters - Google Patents

Abstract

1,086,846. Single sideband amplitude modulation. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. Dec. 3, 1965 [Dec. 4, 1964], No. 51488/65. Heading H3R. In a compatible single sideband modulating system a phase-modulated wave is synthesized from separate components which are added together and amplitude modulated. In one example the phase-modulated wave where the coefficients c and d are chosen to give the desired values of the coefficients a. In the drawing a generator G derives carrier frequencies 4/3#, 1/6#, and 1/3#, from a common source, and a modulation is applied to terminal E of a single sideband generating circuit EM to produce an output m cos (#/3 + w)t, where m is the degree of modulation and w the modulation frequency; this output is added to the #/3 carrier to produce three signals the coefficients d being adjustable by T1 - T3. In channel III this signal is cubed in unit K to produce #3, in channel I the signal is mixed with the 4/3# carrier in M1 to produce #- 1, and in channel II the signal is mixed with the #/6 carrier in M2 and squared in unit Q to produce #2. Each channel includes appropriate filters F, transit time equalizing networks L, and regulators R for adjusting the coefficients c. The signal # passes through a limiter B and amplifier V to a modulator M4 where it is amplitude modulated by the original modulation recovered from the output of EM by demodulator D. Non-linear networks N1-N3 may be provided to make the output signal # more nearly equal to that desired. It is shown that the coefficient C 2 is small so signal # 2 may be omitted; a further signal component # 1 = C 1 [cos #t + d 1 m cos (# + w)t] may be included instead of or in addition to # 2 .