Patent ID: 6944238

Claim:
A method of processing digital signals to be transmitted in analog form, said method comprising: in a digital-to-analog converter (DAC) having a conversion frequency, converting a digital signal having an input frequency to produce an analog signal image output at a radio frequency greater than the input frequency, CHARACTERISED IN THAT: a) said digital signal is one of a plurality of digital input signals each of said digital input signals having an input frequency, and the input frequencies are positioned within non-overlapping portions of a frequency band whose width is one-half the conversion frequency; b) the analog signal image output of the DAC includes a plurality of images of the frequency band, and said plurality of images are grouped in successive non-overlapping frequency bands referred to as zones such that each zone contains one image of each of the plurality of digital input signals; and c) the method further comprises selecting digital input signal images for transmission, wherein at least two digital input signal images are selected from different zones and correspond to different ones of the plurality of digital input signals.