Acquisition:Advanced:Downconverter Frequency Offset Mode Property
- Updated2024-05-08
- 2 minute(s) read
Acquisition:Advanced:Downconverter Frequency Offset Mode Property
Short Name: Downconverter Frequency Offset Mode
Property of niRFSA
Specifies whether to allow NI-RFSA to select the downconverter frequency offset. You can either set an offset yourself or let NI-RFSA select one for you.
Placing the downconverter center frequency outside the bandwidth of your input signal can help avoid issues such as LO leakage.
To set an offset yourself, set this property to Automatic or User-Defined and set either the Downconverter Center Frequency or the Downconverter Frequency Offset properties.
To allow NI-RFSA to automatically select the downconverter frequency offset, set this property to Automatic or Enabled and set the Signal Bandwidth property to describe your expected input signal. The signal bandwidth must be no greater than half the specified value of the Device Instantaneous Bandwidth property, minus a device-specific guard band. Do not set the Downconverter Center Frequency or Downconverter Frequency Offset properties. If all conditions are met, NI-RFSA places the downconverter center frequency outside the signal bandwidth. Set this property to Enabled if you want to receive an error any time NI-RFSA is unable to apply automatic offset.
When you set an offset yourself or do not use an offset, the reference frequency for gain is near the downconverter center frequency, and Downconverter Frequency Offset Mode returns User-Defined. When NI-RFSA automatically sets an offset, the reference frequency for gain is the I/Q carrier frequency, and Downconverter Frequency Offset Mode returns Enabled. Refer to the specifications document for your device for more information about gain, flatness, and reference frequencies.
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Note Below 120 MHz, the PXIe-5841 does not use an LO and Enabled is unavailable. Refer to the PXIe-5841 Automatic Frequency Offset topic for more information about using an automatic offset with an external LO. |
Default Value: Automatic
Supported Devices: PXIe-5830/5831/5832/5841/5842
Related Topics
PXIe-5830 Automatic Frequency Offset
PXIe-5831/5832 Automatic Frequency Offset
PXIe-5841 Automatic Frequency Offset
| Automatic (1903) |
NI-RFSA places the downconverter center frequency outside of the signal bandwidth if the Signal Bandwidth property has been set and can be avoided. |
| Enabled (1901) |
NI-RFSA places the downconverter center frequency outside of the signal bandwidth if the Signal Bandwidth property has been set and can be avoided. NI-RFSA returns an error if the Signal Bandwidth property has not been set, or if the signal bandwidth is too large. |
| User-Defined (1904) |
NI-RFSA uses the offset that you specified with the Downconverter Frequency Offset or Downconverter Center Frequency properties. |
Remarks
The following table lists the characteristics of this property.
| Datatype |  |
| Permissions | Read/Write |
| High-level VIs | N/A |
| Channel-based | No |
| Resettable | Yes |