Patent ID: 8121213

Claim:
A modulation apparatus comprising: a first frequency-increasing single side band (SSB) modulator that performs SSB modulation on a first input symbol to obtain an upper side band (USB) signal; a second frequency-increasing SSB modulator that performs the SSB modulation on a second input symbol to obtain a lower side band (LSB) signal; and a combiner that combines the USB signal and the LSB signal, wherein the second frequency-increasing SSB modulator performs SSB modulation to obtain the LSB signal using a carrier frequency, the carrier frequency being higher than a carrier frequency used in the first frequency-increasing SSB modulator by a symbol frequency of the first input symbol and the second input symbol, such that the LSB signal and the USB signal are multiplexed in the same frequency band, wherein the first frequency-increasing SSB modulator comprises a first Hilbert transformer and obtains the USB signal by multiplying a signal output from the first Hilbert transformer by a signal comprising a sine curve with a frequency (ω 1(first) −ω 0(first) /2), wherein the second frequency-increasing SSB modulator comprises a second Hilbert transformer and obtains the LSB signal by multiplying a signal output from the second Hilbert transformer by a signal comprising a sine curve with a frequency (ω 1(second) +ω 0(second) /2), and wherein ω 0(first) is the symbol frequency of the first input symbol, ω 0(second) is the symbol frequency of the second input symbol, ω 1(first) is the carrier frequency used in the first frequency-increasing SSB modulator, and ω 1(second) is the carrier frequency used in the second frequency-increasing SSB modulator.