High speed binary data communication system

A high speed data transmission system for transmitting a binary data signal over a communications path, said binary data signal clocked at a given period, comprising:

• encoding means responsive to a binary NRZ input data signal to provide at an output an encoded digital signal having time periods greater than multiples of said clock period and at a given bit rate whereby said encoded signal occupies a lesser effective bandwidth than said NRZ signal alone, said lesser effective bandwidth being 1/2 to 1/3 that of said NRZ signal;
• balanced modulator means having an input responsive to said encoded signal and another input adapted to receive a carrier frequency signal to provide at an output a double sideband suppressed carrier signal shifting in phase 180 degrees with changes in said encoded signal;
• filtering means coupled to said output of said balanced modulator to provide a narrow bandwidth less than 1/2 the maximum bandwidth of said sideband signal and by which said carrier frequency and low frequencies are prevented from propagating to reject all sideband frequency components which are lower than 1/4 the bit rate and which are higher than 1/2 the bit rate of said encoded signal to provide at an output a narrow sideband signal for transmission characterized in that transitions between binary levels in said encoded signal are manifested by distinct phase changes in said single sideband signal, said filtering means operative to minimize phase distortion within the sideband signal, while passing only a part of one of said sidebands.