SIGNAL GENERATION APPARATUS, SIGNAL GENERATION METHOD, AND COMPUTER PROGRAM
A signal generation device that includes a digital signal processing unit, a plurality of sub-digital-analog conversion units that respectively converts a plurality of digital signals output from the digital signal processing unit into analog signals, and an analog multiplexer that multiplexes the analog signals output from the plurality of sub-digital-analog conversion units to generate a broadband signal, in which the digital signal processing unit includes a band division unit that divides an input signal for each frequency width of a common divisor of a Nyquist frequency of the plurality of sub-digital-analog conversion units and a clock frequency of the analog multiplexer to generate N (N is a number of divisions) divided signals, a spectrum folding unit that has the N divided signals generated by the band division unit branched on a path, and folds back the branched N divided signals on a frequency axis to obtain complex conjugation to generate N folded divided signals corresponding to the N divided signals, a filter that receives the N divided signals and the N folded divided signals as inputs and generates N composite signals, and a band combining unit that receives the N composite signals as inputs and generates a plurality of digital signals corresponding to the respective sub-digital-analog conversion units.
1 . A signal generation device comprising:
a digital signal processor;
a plurality of sub-digital-analog converters configured to respectively convert a plurality of digital signals output from the digital signal processor into analog signals; and
an analog multiplexer configured to multiplex the analog signals output from the plurality of sub-digital-analog converters to generate a broadband signal,
wherein the digital signal processor includes
a band divider configured to divide an input signal for each frequency width of a common divisor of a Nyquist frequency of the plurality of sub-digital-analog converters and a clock frequency of the analog multiplexer to generate N (N is a number of divisions) divided signals,
a spectrum folder configured to have the N divided signals generated by the band divider branched on a path, and folds back the branched N divided signals on a frequency axis to obtain complex conjugation to generate N folded divided signals corresponding to the N divided signals,
a filter configured to receive the N divided signals and the N folded divided signals as inputs and generates N composite signals, and
a band combiner configured to receive the N composite signals as inputs and generates a plurality of digital signals corresponding to the respective sub-digital-analog-converters.
2 . The signal generation device according to claim 1 , wherein
the band combiner includes a plurality of band combiners configured to generate the digital signal for each of the sub-digital-analog-converters, and
each of the band combiners generates the digital signal for each of the sub-digital-analog converters by combining bands of the composite signals that are different from each other.
3 . The signal generation device according to claim 1 , wherein
the filter includes 2N×N convolution arithmetic operators and N adders,
the 2N×N convolution arithmetic operators receive the N divided signals and the N folded divided signals as inputs, and multiply the input N divided signals and the input N folded divided signals by a response function, and
the N adders output N composite signals obtained by adding the N divided signals multiplied by the response function and the N folded divided signals multiplied by the response function to the band combiner.
4 . The signal generation device according to claim 1 , wherein
the Nyquist frequency of the plurality of sub-digital-analog converters is larger than the clock frequency of the analog multiplexer.
5 . A signal generation method comprising:
by a digital signal processor, dividing an input signal for each frequency width of a common divisor of a Nyquist frequency of a plurality of sub-digital-analog converters and a clock frequency of an analog multiplexer to generate N (N is a number of divisions) divided signals;
by the digital signal processor, branching the generated N divided signals on a path and folding back the branched N divided signals on a frequency axis to obtain complex conjugation to generate N folded divided signals corresponding to the N divided signals;
by the digital signal processor, receiving the N divided signals and the N folded divided signals as inputs, and generating N composite signals;
by the digital signal processor, receiving the N composite signals as inputs and generating a plurality of digital signals corresponding to the respective sub-digital-analog converters;
by the plurality of sub-digital-analog converters, converting the plurality of digital signals output from the digital signal processor into analog signals; and
by an analog multiplexer, multiplexing the analog signals output from the plurality of sub-digital-analog converters to generate a broadband signal.
6 . A non-transitory storage medium that stores a program for making a computer perform processes, the processes comprising:
dividing an input signal for each frequency width of a common divisor of a Nyquist frequency of a plurality of sub-digital-analog converters and a clock frequency of an analog multiplexer to generate N (N is a number of divisions) divided signals;
branching the generated N divided signals on a path and folding back the branched N divided signals on a frequency axis to obtain complex conjugation to generate N folded divided signals corresponding to the N divided signals;
receiving the N divided signals and the N folded divided signals as inputs, and generating N composite signals;
receiving the N composite signals as inputs and generating a plurality of digital signals corresponding to the respective sub-digital-analog converters;
converting the plurality of digital signals into analog signals; and
multiplexing the analog signals to generate a broadband signal.