NI 5441
Carrier Frequency

The carrier frequency determines the frequency of the cosine waves (both I and Q) exported from the NCO. You can use the Carrier Frequency property or the NIFGEN_ATTR_OSP_CARRIER_FREQUENCY attribute to set the carrier frequency. This frequency is programmable during signal generation.

For IQ Rates below the interpolation range of the OSP block, NI-FGEN selects a lower Sample clock rate in order to achieve the requested IQ Rate. Because the carrier cannot be more than 0.43 × Sample Rate, these lower sample rates translate to lower valid carrier rates. The largest carrier frequency that can be generated for a given IQ Rate with a maximum CIC interpolation of 256× can be calculated using the following formula:

Max Carrier Frequency = IQ Rate × 256 × FIR Interpolation × 0.43

The following table summarizes the maximum carrier frequency for all FIR interpolation factors.