NI 5670 Arb Waveform Mode Tuning Speed Factors
A user-specified complex IQ baseband signal is passed to NI-RFSG in arb waveform mode. Then, depending on different parameters, NI-RFSG upconverts the signal to IF and uploads it to the AWG module onboard memory.
In arb waveform mode, the following main factors affect RF signal generator tuning time:
- Waveform size—The bigger the waveform the longer it takes to be recalculated and uploaded to AWG module onboard memory. Increasing the waveform size increases the required tuning time in a linear fashion.
- Digital IF equalization—The process of digitally equalizing the waveform is computationally demanding and adds to tuning times.
- Phase continuity—If the Phase Continuity Enabled property or the NIRFSG_ATTR_PHASE_CONTINUITY_ENABLED attribute is enabled, NI-RFSG may repeat the IQ waveform before upconverting it to IF to ensure phase continuity. Repeating the IQ waveform changes the size of the IF waveform and, as noted, increases the NI RF signal generator tuning time. The final IF waveform size depends on the frequency tolerance, desired frequency, and input size.
- Desired frequency—A change in the RF output frequency may require calculation of a new IF waveform centered at a different IF frequency. This situation occurs when the RF frequency change desired is not a multiple of 5 MHz (for signal bandwidths ≤ 10 MHz and CW mode) or 1 MHz (for signal bandwidths > 10 MHz).
- Available RAM—Large waveforms require a large amount of RAM. If sufficient RAM is unavailable, the system uses virtual memory, which dramatically increases execution times.
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Note Refer to the specifications document that shipped with your RF signal generator device for specific tuning times. |
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Tips The following measures can decrease arbitrary waveform tuning times:
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