PXIe-5603 Downconverter IF Filter

You can allow NI-RFSA to automatically control IF filtering or you can manually select the IF filter.

Manual selection is useful when the PXIe-5622 IF digitizer is not being used as well as in other applications, such as in-band retuning.

The PXIe-5603 supports the following IF bandpass filters:

  • Through—Provides a nominal 80 MHz bandwidth at -6 dB, although the effective bandwidth of the device may be further reduced by the anti-aliasing filter in the digitizer or other options. The through path has a nominal IF output frequency of 187.5 MHz.
  • 300 kHz —Provides a nominal 300 kHz bandwidth at -3 dB and a nominal IF output frequency of 199 MHz.

    • IF Filter Selection in Spectrum Acquisitions

    For spectrum acquisitions, NI-RFSA automatically selects the appropriate filter based on the requested acquisition span.

    You can change the bandwidth using the Device Instantaneous Bandwidth property or the NIRFSA_ATTR_DEVICE_INSTANTANEOUS_BANDWIDTH attribute. You can use this property or attribute to determine the actual bandwidth achieved by the downconverter in (external digitizer mode) or the PXIe-5667.

    When you set the Low-Frequency Bypass Enabled property to Enabled or the NIRFSA_ATTR_LOW_FREQUENCY_BYPASS_ENABLED attribute to NIRFSA_VAL_ENABLED, the downconverter analog IF bandwidth filters are selected. For all other signal paths, the downconverter analog IF filters are bypassed to allow the PXIe-5694 IF conditioning module to provide the analog IF filtering.

    IF Filter Selection in I/Q Acquisitions

    For I/Q acquisitions, NI-RFSA defaults to the widest IF bandwidth available.

    You can change the bandwidth using the Device Instantaneous Bandwidth property or the NIRFSA_ATTR_DEVICE_INSTANTANEOUS_BANDWIDTH attribute. You can also change the bandwidth using the IF Filter Bandwidth property or the NIRFSA_ATTR_IF_FILTER_BANDWIDTH attribute. You can use these properties or attributes to determine the actual bandwidth achieved by the PXIe-5603/5605 or the PXIe-5667.
    Note When you set a bandwidth, NI-RFSA selects the smallest bandwidth filter that is at least as large as your specified bandwidth.