Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
214 words
A signal transmitting apparatus using orthogonal frequency division multiplexing, comprising: an inverse fast Fourier transform circuit for converting a digital information signal into a first multi-value QAM modulation signal; a guard interval setting circuit for periodically generating a guard interval signal equal to a time segment of the first multi-value QAM modulation signal, and inserting the guard interval signal into the first multi-value QAM modulation signal to convert the first multi-value QAM modulation signal into a second multi-value QAM modulation signal; and a clock signal generating circuit for generating a first clock signal which drives the inverse fast Fourier transform circuit, and generating a second clock signal which drive the guard interval setting circuit; wherein the inverse fast Fourier transform circuit comprises means for generating a pilot signal which corresponds to a given-order carrier, and adding the pilot signal to the first multi-value QAM modulation signal, wherein the pilot signal has a predetermined frequency and an angle modulation component which remains constant over a plurality of symbol periods, wherein the pilot signal corresponding to a given integer times its wavelength is present in a guard interval occupied by the guard interval signal in the second multi-value QAM modulation signal, and wherein the pilot signal is continuously present over the guard interval and another interval.
Claim 2
Dependent Claim
20 words
The signal transmitting apparatus of claim 1, wherein the first clock signal and the second clock signal are the same.
Claim 3
Dependent Claim
33 words
The signal transmitting apparatus of claim 1, wherein a ratio between the frequency of the pilot signal and a frequency of the first clock signal is equal to a ratio between predetermined integers.
Claim 4
Dependent Claim
82 words
A signal receiving apparatus using orthogonal frequency division multiplexing, comprising: first means for reproducing a pilot signal from a multi-value QAM modulation signal by angle demodulation; second means for converting a frequency of the reproduced pilot signal to change the reproduced pilot signal into a clock signal; and a fast Fourier transform circuit for converting the multi-value QAM modulation signal into a digital information signal; wherein the fast Fourier transform circuit Is driven by the clock signal generated by the second means.
Claim 5
Dependent Claim
200 words
A signal transmitting apparatus using orthogonal frequency division multiplexing, comprising: an inverse fast Fourier transform circuit for converting a digital information signal into a first multi-value QAM modulation signal; a guard interval setting circuit for periodically generating a guard interval signal equal to a time segment of the first multi-value QAM modulation signal, and inserting the guard interval signal into the first multi-value QAM modulation signal to convert the first multi-value QAM modulation signal into a second multi-value QAM modulation signal; and a clock signal generating circuit for generating a first clock signal which drives the inverse fast Fourier transform circuit, and generating a second clock signal which drive the guard interval setting circuit; wherein the inverse fast Fourier transform circuit comprises means for setting a given-order carrier as a reference carrier, wherein the given-order carrier corresponding to a given integer times approximately its half wavelength is present in a guard interval occupied by the guard interval signal in the second multi-value QAM modulation signal, and wherein the inverse fast Fourier transform circuit comprises means for changing a phase of the reference carrier for every symbol interval by an amount corresponding to a given odd number times its quarter wavelength.
Claim 6
Dependent Claim
35 words
The signal transmitting apparatus of claim 5, wherein the first multi-value QAM modulation signal generated by the inverse fast Fourier transform circuit changes between a real part and an imaginary part for every symbol interval.
Claim 7
Dependent Claim
35 words
The signal transmitting apparatus of claim 5, wherein the inverse fast Fourier transform circuit comprises means for providing the reference carrier with information of a reference amplitude level and information of a reference angle level.
Claim 8
Dependent Claim
64 words
A signal receiving apparatus using orthogonal frequency division multiplexing, comprising: means for detecting a phase change of a reference carrier in a multi-value QAM modulation signal, and generating a symbol sync signal in response to the detected phase change; and a fast Fourier transform circuit for converting the multi-value QAM modulation signal into a digital information signal in response to the symbol sync signal.