NI 5441
Using an External Clock with the OSP Block

Some applications may require lower jitter or phase noise than the onboard High-Resolution clock of the NI 5441. You can use an external clock source to achieve spectral purity at any arbitrary IQ Rate. To determine the frequency of the sample rate for the external clock source, complete the following steps for the NI 5441.

1. Set the Sample Clock Source property or the NIFGEN_ATTR_SAMPLE_CLOCK_SOURCE attribute to the external clock source you are using.
2. Set the IQ Rate property or the NIFGEN_ATTR_OSP_IQ_RATE attribute.
3. (Optional) Set the EM FIR Interpolation Factor property or the NIFGEN_ATTR_OSP_FIR_FILTER_INTERPOLATION attribute.
4. (Optional) Set the CIC Interpolation Factor property or the NIFGEN_ATTR_OSP_CIC_FILTER_INTERPOLATION attribute.
5. Read the value of the Sample Rate property or the NIFGEN_ATTR_ARB_SAMPLE_RATE attribute.
6. Set the external clock source sample rate to the EM frequency of the Sample Rate property you just read.
7. Validate that the external Sample clock source is connected to the NI 5441 connector specified in the Sample Clock Source property or the NIFGEN_ATTR_SAMPLE_CLOCK_SOURCE attribute and generating a clock before you continue configuring the NI 5441.

For more information about using external clocks with the NI 5441, refer to External Sample Clock Sources.