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 WLAN Analysis Toolkit in which the issue was reported. If you discover the issue appears in an earlier version of the NI WLAN Analysis Toolkit 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- Resolved Version - Version in which the issue was resolved or was no longer applicable.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).
Known Issues by Severity
||Decoded bits may not be correct for DSSS signals in certain cases
Bits decoded from the received DSSS frame may not be correct in the following cases:
||Higher EVM values for the chips at the beginning of the DSSS signal payload with 33 Mbps data rate
When a DSSS packet with a 33 Mbps data rate is analyzed, the error vector magnitude (EVM) for around 10 chips at the beginning of the packet may be higher than the remaining chips. The chips at the beginning of the packet belong to the shift portion, which is needed for clock switching.
Workaround: Set the Measurement Start Location property or NIWLANA_DSSS_DEMOD_MEASUREMENT_START_LOCATION attribute to the number of chips you want to avoid from the beginning of the packet.
|330141||The RMS EVM, Data RMS EVM, and Pilot RMS EVM results may not return a number (NaN)
When you set the Standard property to 80211A/G/J/P OFDM or NIWLANA_STANDARD attribute to NIWLANA_VAL_STANDARD_80211AGJP_OFDM, the RMS EVM, Data RMS EVM, and Pilot RMS EVM results may not return a number (NaN) in the following cases:
|328584||Inaccurate CFO estimation using Preamble and Data for OFDM signals
When you set the CFO Estimation Method property to Preamble and Data or NIWLANA_OFDM_DEMOD_CFO_ESTIMATION_METHOD attribute to NIWLANA_VAL_CFO_ESTIMATION_METHOD_PREAMBLE_AND_DATA, the carrier frequency offset (CFO) estimate may be inaccurate for high sampling clock offsets and large number of symbols on which the measurement is performed. For example, if the sampling clock offset is 20 ppm, the estimated CFO becomes less accurate if the number of symbols on which the measurement is performed is greater than 700. Inaccurate CFO estimation degrades EVM.
Workaround: Set the CFO Estimation Method property to Preamble Only or NIWLANA_OFDM_DEMOD_CFO_ESTIMATION_METHOD attribute to NIWLANA_VAL_CFO_ESTIMATION_METHOD_PREAMBLE_ONLY. If the issue still persists, try decreasing the Maximum Symbols Used property or NIWLANA_OFDM_DEMOD_MAXIMUM_SYMBOLS_USED attribute value.
||Out-of-band spurious signals may affect EVM measurement
EVM measurement quality may be affected by out-of-band spurious signals if the RF signal analyzer bandwidth (defined as 0.8 * I/Q rate) is significantly greater than the channel bandwidth.
Workaround: Enable the software low-pass filter to reject the out-of-channel noise.
||I/Q gain imbalance and quadrature skew measurements may be incorrect in 802.11n Greenfield mode
For a multiple channel 802.11n Greenfield signal, the I/Q gain imbalance and quadrature skew measurements may be inaccurate if spatial mapping at the transmitter is not set to direct.
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. Please contact us if you find a workaround for an issue that is not listed in the document.