Changing Carrier Frequency on the Fly While Maintaining Phase Continuity Primary Software: Driver Software>>NI-RFSGPrimary Software Version: 1.2 Primary Software Fixed Version: 1.2 Secondary Software: N/A Hardware: Modular Instruments>>RF Measurement Devices>>PXI-5670, Modular Instruments>>RF Measurement Devices>>PXI-5671
Problem: Using my PXI-5670 RF generator, I want to change the carrier frequency on the fly while maintaining phase continuity of my signal. However, when I try to change the frequency on the fly the signal does not seem to maintain phase continuity. What seems to be the problem? Solution: The PXI-5670 RF generator does not have a digital upconverter (DUC) and therefore when changing the frequency, a new waveform is loaded to the ARB and hence you are losing phase continuity of your signal. To be able to generate your signal and change the frequncy on the fly while maintaining phase continuity, you would need to use the PXI-5671 that has the PXI-5441 ARB. The PXI-5441 ARB has an onboard DUC that is used for frequency translation. In other words, the DUC has an NCO circuitry that takes care of the carrier frequency so when you change the frequency all that is happening in hardware is that the NCO generates the new frequency and multiplies it by the IQ data of your waveform. Related Links: Attachments:
Report Date: 03/04/2006 Last Updated: 03/05/2006 Document ID: 3V3DHDKQ |
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