Specifies the I/Q rate for the acquisition.

Syntax

NIRFSA_ATTR_IQ_RATE

Numeric Value

Data Type

Access

Applies To

1150007

ViReal64

Read/Write

N/A

Remarks


The value is expressed in samples per second (S/s).

Refer to the NIRFSA_ATTR_DEVICE_INSTANTANEOUS_BANDWIDTH attribute for more information about device specific instantaneous bandwidth limits. You can also refer to the NI PXIe-5665 Specifications for more information about instantaneous bandwidth device specifications.

Note

For the PXIe-5663/5663E/5665/5667/5668, NI-RFSA enables dithering by default. At I/Q rates above 50 MS/s, the dither noise can affect phase coherency performance and leak into the lower frequencies and the upper frequencies of the IF passband. Refer to the NIRFSA_ATTR_DIGITIZER_DITHER_ENABLED attribute for more information about dithering.

For the PXIe-5663/5663E/5665/5667, when you set the NIRFSA_ATTR_DIGITIZER_SAMPLE_CLOCK_TIMEBASE_SOURCE attribute to NIRFSA_VAL_ONBOARD_CLOCK_STR, the downconverter instantaneous bandwidth is greater than or equal to the coerced I/Q rate times 0.8. For the PXIe-5665, the actual signal bandwidth is further limited by the combination of the chosen IF filter and anti-aliasing filter.

PXI-5661: You should not need to configure an I/Q rate higher than 25 megasamples per second (MS/s) because the PXI-5600 RF downconverter bandwidth is 20 MHz. If you configure a higher I/Q rate, you may see aliasing effects at negative frequencies because the IF frequency of the PXI-5600 is 15 MHz.

PXIe-5663/5663E: Your maximum allowed instantaneous bandwidth depends on the I/Q carrier frequency you use. Refer to the PXIe-5601 RF downconverter overview for more information about instantaneous bandwidth.

PXIe-5665: Your maximum allowed instantaneous bandwidth depends on the downconverter center frequency if you have enabled the preselector (YIG-tuned filter).

PXIe-5667: Your maximum allowed instantaneous bandwidth depends on the selected RF preselector filter and whether the preselector on the RF downconverter is enabled.

PXIe-5668: Your maximum allowed instantaneous bandwidth depends on the downconverter center frequency you use and whether or not you enable the highpass filter or preselector (YIG-tuned filter).

Units: S/s

Default Values:

PXIe-5842 (4 GHz bandwidth option) using the 4 GHz Bandwidth personality: 5 GS/s only.

All Other Devices: 1 MS/s

Supported Devices: PXIe-5644/5645/5646, PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5820/5830/5831/5832/5840/5841/5842/5860

Related Topics

I/Q Modulation

High-Level Functions: