| 主权项 |
1. A method of digital down conversion of a signal in a radio frequency (RF) receiver, the method comprising:
selecting a first sampling frequency as the selected sampling frequency to sample an analog signal, the selecting being based at least in part on a predetermined bandwidth and a safety margin; determining whether a bandwidth of the analog signal falls substantially within a predetermined frequency zone associated with the first sampling frequency; when the bandwidth of the analog signal does not fall substantially within the predetermined frequency zone, then selecting a second sampling frequency, higher than the first sampling frequency, as the selected sampling frequency to sample the analog signal; sampling the analog signal at the second sampling frequency as the selected sampling frequency to produce a digitally down converted signal; and digitally demodulating the sampled signal at a demodulation frequency that is tunable, the demodulation frequency based at least in part on a carrier frequency of the analog signal wherein the demodulation frequency depends on whether frequency inversion is applied to the signal, and when frequency inversion is not applied to the signal, the demodulation frequency is determined by the relationship:fdemod=fcarrier-fs⌊fcarrierfs⌋;and
when frequency inversion is applied to the signal, the demodulation frequency is determined by the relationship:fdemod=fs-(fcarrier-fs⌊fcarrierfs⌋); where fdemod is the demodulation frequency, fcarrier is the carrier frequency, fs is the sampling frequency and the function, └arg┘, denotes the greatest integer less than the argument. |
