Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
170 words
(1) A group modulator for providing a plurality of frequency division multiplexed modulated signals having different carrier frequency from one another relating to a plurality of input digital data comprising; a time division multiplexer for effecting time division multiplex of input digital data, a mapping circuit for assigning amplitude and phase for each pattern of the multiplexed signal to provide I-channel signal and Q-channel signal according to the modulation system which modulates said input digital data, a pulse shaping circuit for restricting bandwidth of output of said mapping circuit, a frequency shift circuit receiving an external carrier control signal so that the frequency of said output of said pulse shaping circuit is shifted by the frequency defined by said carrier control signal, an accumulator for accumulating output of said frequency shift circuit during a predetermined period, a digital-to-analog converter for converting output of said accumulator from digital form to analog form, and a modulator for modulating output of said digital-to-analog converter to provide frequency division multiplexed modulated high frequency signal.
Claim 2
Dependent Claim
33 words
(2) A group modulator according to claim 1, wherein said modulator is a quadrature modulator, and said mapping circuit provides I-channel signal and Q-channel signal having phase difference by 90° for quadrature modulation.
Claim 3
Dependent Claim
31 words
(3) A group modulator according to claim 1, wherein said digital-to-analog converter has a latch circuit to keep an input signal to the level at the initial stage of the conversion.
Claim 4
Dependent Claim
24 words
(4) A group modulator according to claim 1, wherein a low pass filter is provided between output of said digital-to-analog converter and said modulator.
Claim 5
Dependent Claim
44 words
(5) A group modulator according to claim 1, wherein a multiplicity control is provided so that a number of multiplicity in said time division multiplexer is adjustably controlled according to a multiplicity signal which is applied to said multiplicity control from an outside circuit.
Claim 6
Dependent Claim
37 words
(6) A group modulator according to claim 1, wherein said modulator is a frequency converter, and a bandpass filter is provided at output of said frequency converter to remove undesirable side band generated in said frequency converter.
Claim 7
Dependent Claim
20 words
(7) A group modulator according to claim 5, wherein multiplicity is adjusted according to amount of traffic of input data.
Claim 8
Dependent Claim
53 words
(8) A group modulator according to claim 1, wherein said frequency shift circuit is implemented by a plurality of digital multipliers each providing product of input signal of said frequency shift circuit and instantaneous value of said shift frequency, and an adder for providing sum of outputs of two of said digital multipliers.
Claim 9
Dependent Claim
51 words
(9) A group modulator according to claim 1, wherein said frequency shift circuit is implemented by a plurality of ROM's which store product of input signal of said frequency shift circuit and instantaneous value of said shift frequency, and an adder for providing sum of outputs of two of said ROM's.