Multiplex system employing multiple quadrature subcarriers

Claim 3

The method recited in claim 1 wherein the frequency of the reference wave is twice the frequency of the pilot carrier wave, and the frequency of each of the altErnating current signals is one half the frequency of the pilot carrier wave, and wherein modulating the reference wave includes the steps of: applying said reference wave and said alternating current signals to a balanced modulator wherein said reference wave is double sideband suppressed carrier amplitude modulated by said alternating current signals to provide said second and third subcarrier waves.

Claim 4

The method recited in claim 2 wherein the steps of modulating each of said subcarriers include the step of: double sideband suppressed subcarrier amplitude modulating each of said subcarriers with the signal associated therewith.

Claim 5

Apparatus for transmitting three signals within a predetermined band of frequencies, including in combination: means for generating a pilot carrier having a predetermined frequency; means for generating a first subcarrier wave; first modulating means connected to said first subcarrier generating means for modulating said first subcarrier wave with a first signal having a first predetermined bandwith; means for generating a second subcarrier wave having the same frequency as said first subcarrier wave and in quadrature therewijh; sideband generating means coupled to said second subcarrier generating means for generating a pair of equally spaced sidebands about said second subcarrier wave to thereby generate third and fourth subcarrier waves, said sideband generating means including means for modulating said second subcarrier wave by two quadrature related alternating current signals, each having a frequency predeterminedly related to said pilot carrier wave, whereby the quadrature related sidebands resulting from the modulation of said second subcarrier wave by said alternating current signals provide the third and fourth subcarrier waves; second and third modulating means connected to said sideband generating means for modulating said third and fourth subcarriers with second and third signals, each of said second and third signals having a bandwidth narrower than said first predetermined bandwidth; and means connected to said pilot carrier generating means, said first modulating means and said second and third modulating means for receiving and combining said pilot carrier and said first, third and fourth modulated subcarriers to provide a composite signal.

Claim 6

Apparatus for transmitting three signals within a predetermined band of frequencies, including in combination: means for generating a pilot carrier having a predetermined frequency; means for generating a first subcarrier wave; first modulating means connected to said first subcarrier generating means for modulating said first subcarrier wave with a first signal having a first predetermined bandwith; means for generating a second subcarrier wave having the same frequency as said first subcarrier wave and in quadrature therewijh; sideband generating means coupled to said second subcarrier generating means for generating a pair of equally spaced sidebands about said second subcarrier wave to thereby generate third and fourth subcarrier waves, said sideband generating means including means for modulating said second subcarrier wave by two quadrature related alternating current signals, each having a frequency predeterminedly related to said pilot carrier wave, whereby the quadrature related sidebands resulting from the modulation of said second subcarrier wave by said alternating current signals provide the third and fourth subcarrier waves; second and third modulating means connected to said sideband generating means for modulating said third and fourth subcarriers with second and third signals, each of said second and third signals having a bandwidth narrower than said first predetermined bandwidth; and means connected to said pilot carrier generating means, said first modulating means and said second and third modulating means for receiving and combining said pilot carrier and said first, third and fourth modulated subcarriers to provide a composite signal.

Claim 7

Apparatus as recited in claim 4 wherein said means for modulating said second subcarrier wave by two quadrature related alternating current components includes a balanced modulator.

Claim 8

Apparatus for deriving three signals from a composite signal which has a first component having a predetermined bandwith modulating a first suppressed subcarrier to thereby provide a first signal, a second signal having a second suppressed subcarrier having a frequency equal to the frequency of said first suppressed subcarrier and in quadrature therewith, said second suppressed subcarrier having a pair of equally spaced suppressed subcarriers thereabout providing third and fourth suppressed subcarriers, and second and third components modulating said third and fourth suppressed subcarriers, said second and third components each having a predetermined bandwidth less than one half the bandwidth of said first signal component, said composite signal including a pilot carrier wave, said apparatus including in combination: means for receiving said composite signal; reference carrier means coupled to said receiving means and responsive to said pilot carrier wave for generating a first fixed frequency reference wave having a frequency equal to the frequency of said first suppressed subcarrier and a second frequency reference wave having a frequency different than the frequency of said first fixed frequency reference wave, the frequency of said second fixed frequency reference wave being equal to a predetermined multiple of the frequency of one of said third and fourth suppressed subcarriers; and demodulator means connected to said receiving meanS and said reference carrier means and responsive to said first and second signals and said first and second fixed frequency reference waves to provide three output signals representative of said first, second and third signal components in response to said composite signal, said demodulator means having first suppressed subcarrier demodulator means responsive to said first signal and said first fixed frequency reference wave for demodulating said first signal and providing a detected first signal component representative of the first signal component modulating said first suppressed subcarrier, said demodulator means further having second suppressed subcarrier demodulator means for demodulating said second signal and providing detected second and third signal components representative of the signal components modulating said third and fourth subcarrier waves, said second suppressed subcarrier demodulator means including 90* phase shifting means responsive to said first fixed frequency reference wave for providing a phase shifted reference wave, and means responsive to said phase shifted reference wave, said second fixed frequency reference wave and said second signal for demodulating said second signal under the control of said phase shifted reference wave and said second fixed frequency reference wave.

Claim 9

Apparatus for deriving three signals from a composite signal which has a first component having a predetermined bandwith modulating a first suppressed subcarrier to thereby provide a first signal, a second signal having a second suppressed subcarrier having a frequency equal to the frequency of said first suppressed subcarrier and in quadrature therewith, said second suppressed subcarrier having a pair of equally spaced suppressed subcarriers thereabout providing third and fourth suppressed subcarriers, and second and third components modulating said third and fourth suppressed subcarriers, said second and third components each having a predetermined bandwidth less than one half the bandwidth of said first signal component, said composite signal including a pilot carrier wave, said apparatus including in combination: means for receiving said composite signal; reference carrier means coupled to said receiving means and responsive to said pilot carrier wave for generating a first fixed frequency reference wave having a frequency equal to the frequency of said first suppressed subcarrier and a second frequency reference wave having a frequency different than the frequency of said first fixed frequency reference wave, the frequency of said second fixed frequency reference wave being equal to a predetermined multiple of the frequency of one of said third and fourth suppressed subcarriers; and demodulator means connected to said receiving meanS and said reference carrier means and responsive to said first and second signals and said first and second fixed frequency reference waves to provide three output signals representative of said first, second and third signal components in response to said composite signal, said demodulator means having first suppressed subcarrier demodulator means responsive to said first signal and said first fixed frequency reference wave for demodulating said first signal and providing a detected first signal component representative of the first signal component modulating said first suppressed subcarrier, said demodulator means further having second suppressed subcarrier demodulator means for demodulating said second signal and providing detected second and third signal components representative of the signal components modulating said third and fourth subcarrier waves, said second suppressed subcarrier demodulator means including 90* phase shifting means responsive to said first fixed frequency reference wave for providing a phase shifted reference wave, and means responsive to said phase shifted reference wave, said second fixed frequency reference wave and said second signal for demodulating said second signal under the control of said phase shifted reference wave and said second fixed frequency reference wave.