Patent ID: 7375667

Claim:
A method of supplying a synthesized output signal, the method comprising the steps of: (a) selecting one of two non-disjoint bands B 1 or B 2 respectively representing staggered Nyquist regions that are a First Nyquist region for a basic sampling frequency FS 1 and a Second Nyquist region for an alternate sampling frequency FS 2 , where P/Q is some fraction less than one and FS 2 =(P/Q)(FS 1 ); (b) forming a sequence of digital values that represent, with samples at the sampling frequency for the band chosen in step (a), an analog waveform corresponding to the synthesized output signal; (c) if B 1 is selected, then: (c1) applying at sampling frequency FS 1 the sequence of digital values of step (b) to a digital input of a digital to analog converter; (c2) applying an analog output of the digital to analog converter to a low pass reconstruction filter, of cutoff frequency FS 1 /2 less a guard band, to produce a synthesized signal in the band B 1 ; and (c3) supplying an output of the low pass reconstruction filter of step (c2) as the synthesized output signal; else (d) if B 2 is selected, then: (d1) applying at sampling frequency FS 2 the sequence of digital values of step (b) to a digital input of a digital to analog converter; (d2) applying an analog output of the digital to analog converter to a bandpass reconstruction filter, of passband FS 2 /2 plus a guard band to FS 2 less a guard band, to produce a synthesized signal in the band B 2 ; and (d3) supplying an output of the bandpass reconstruction filter of step (d2) as the synthesized output signal.