When tuning an SDR 1000, if spur reduction is turned off, the DDS is tuner 11025 khz below the frequency of interest and the software (DttSP) oscillator is set to -11025 khz to recover the frequency of interest. This works well but for the spurs from the DDS.
If spur reduction is turned on (the normal case) the DDS is tuned to the nearest low spur point (as documented by some of the AD docs) and then DttSP oscillator is set to an appropriate value to recover the signal of interest. This generally results in a DttSP oscillator value between -9.5 and -12.5 khz.
On the SoftRock all the tuning is done with the DttSP oscillator and it ranges over +/- 24 khz - giving a tuning range of 48 khz.
Regards,
Bill (kd5tfd)
