From SIG Symbols (Number of Spatial Streams) (802.11n/ac/ax/be)
When is selected, the VSA uses information detected within the HT-SIG High-Throughput SIGNAL field or VHT very high throughput (VHT) physical (PHY) layer protocol data unit (PPDU):A PPDU transmitted using the TXVECTOR FORMAT parameter equal to VHT.-SIG sections of the preamble to determine the number of Spatial Streams.
Assuming the signal has correct SIG symbols, this method of determining the number of spatial streams is more robust than the Automatic setting. This method can correctly handle all 802.11n/ac signal formats regardless of the number of streams, input channels, or HT high throughput-LTF Long Training field/VHT-LTF symbols.
See Also
