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This document contains the NI-USRP 1.2 known issues that were discovered before and since the release of NI-USRP 1.2. Not every issue known to NI appears on this list; it is intended to show the most severe and common issues that can be encountered.
Each issue appears as a row in the table and includes the following fields:
Issue ID - The number in at the top of each of the cells in the first column. When you report an issue to NI, you may be given this ID, you can also find IDs posted by NI on the discussion forums or in Knowledge Base articles. "N/A" indicates that there is no ID assigned to the issue.
Issue Title (in italics) - Describes the issue in one sentence or less.
Problem Description - A few sentences which describe the problem in further detail. The brief description given does not necessarily describe the problem in full detail, and it is expected that you may want more information on an issue. If you would like more information on an issue, contact NI and reference the ID number given in the document.
Workaround - Possible ways to work around the problem. The workarounds that appear in the document are not always tested by NI and are not guaranteed to resolve the issue. If a workaround refers you to the NI KnowledgeBase, visit www.ni.com/kb/ and enter the KnowledgeBase number in the search field to locate the specific document.
Reported Version - The earliest version of NI-RFSG in which the issue was reported. If you discover the issue appears in an earlier version of NI-RFSG than is reported in this field, report the discrepancy to NI to have the field updated.
Resolved Version - Version in which the issue was resolved or was no longer applicable. "N/A" indicates that the issue has not been resolved.
Date Added - The date the issue was added to the document (not the reported date).
Transients exist for both Tx and Rx.
For IQ sampling rates that are divisible by 2, transients may appear in the first 20 or so samples for both Rx and Tx.
Workaround: For Tx, pad the end of each generated waveform with zeros to eliminate the transient samples at the beginning of the subsequent waveform generation. For Rx, acquire sufficient extra data before the expected beginning of the packet and discard the first 20 samples.
Poor streaming performance for multi-device sessions
NI-USRP sessions configured to control multiple devices exhibit lower than expected streaming performance. The streaming rate for multi-device sessions should be approximately half that of single device sessions, but actual performance is less than half. For multi-device sessions, it is sometimes not possible to stream at high I/Q rates.
NI-USRP returns one of the following errors during Tx: "Packet loss between host and device." or "Packet loss within a burst."
A continuous Tx operation that uses a high IQ sampling rate and a small waveform size per write creates a very large number of underflows. The underflows cause the operation to eventually error out with one of the packet loss errors. When one of these errors occurs, a packet has actually been dropped between the host and the device.
Workaround: Implement one or more of the following changes: -Use a larger write size in each write call. -Use a smaller IQ sampling rate, if possible. -Use a finite Tx operation that provides all the data in a single write call and sets the end of data? parameter of the write VI to TRUE, if possible.
NI-USRP incorrectly coerces carrier frequency for the NI 292x.
If you set the carrier frequency to a value that is out of range for the NI 292x, NI-USRP does not coerce the carrier frequency to a value within range of the NI 292x.
Workaround: Set the carrier frequency to a value within range of your device. Select values within the following ranges: NI-2920: 50 MHz - 2.2 GHz. NI-2921: 2.4 GHz - 2.5 GHz; 4.9 GHz - 4.9 GHz.
niUSRP Write Tx Data sometimes ignores timeout if end of data? is true
If you call the niUSRP Write Tx Data VI with end of data? set to true, the driver will in some cases ignore the timeout. If the device is configured to start generating at a time that is later than the timeout, the driver will wait for the device to start generating, even if the wait time exceeds the timeout.
Workaround: Do not set Start Trigger times further in the future than you want to wait.
NI-USRP Configuration Utility fails to reset after Firmware/FPGA Upgrade
The utility reports that it was unable to reset the device after a firmware/FPGA upgrade. The upgrade was successful, but the reset action did not complete.
Workaround: Unplug and replug the device to manually power cycle the device and complete the reset action.
Reported Version: 1.1
Resolved Version: N/A
Contact NI regarding this document or issues in the document. If you contact NI in regards to a specific issue, reference the ID number given in the document. The ID number contains the current issue ID number as well as the legacy ID number (use the current ID number when contacting NI). You can contact us through any of the normal support channels including phone, email, or the discussion forums. Visit the NI Website to contact us. Also contact us if you find a workaround for an issue that is not listed in the document.