About Symbol Table (802.11b/g DSSS/CCK/PBCC)

When 802.11b/g DSSS Direct sequence spread spectrum. The data transmission scheme (sometimes referred to as a "'modulation" scheme) used in 802.11b WLANs. DSSS uses a radio transmitter operating at a fixed centre frequency, but using a relatively broad range of frequencies, to spread data transmissions over a fixed range of the frequency band. 802.11a and 802.11g (when not operating in 802.11b mode) use Orthogonal Frequency Division Multiplexing (OFDM)./CCK complementary code keying/PBCC packet binary convolutional code demodulation is enabled, selecting the Syms/Err trace data displays the symbol table. The symbol table shows the error summary data and the symbol data (binary bits) for each PSDU 1) PHY Service Data Unit, or 2) PLCP SDU payload data symbol.

Symbol Data

The lower section of the symbol table shows the symbol data bits for the demodulated signal as described in the following table for the specified demodulation format:

Modulation Format	Symbol Table Data
Barker, CCK	Shows the PSDU Payload symbol data bits.
PBCC	Shows the coded, covered symbol data bits (PSDU Payload data after descrambling)

For the demodulated PSDU payload data symbols, only the data bits for the specified measurement interval and offset will be displayed.

The first bit in the symbol table corresponds to the first bit of the first payload data symbol following the PLCP Physical layer convergence protocol Preamble/Header data. For PPDU PLCP Protocol data unit frames with long preamble its symbol number 192 and for short preamble its symbol number 96

When the symbol table marker is enabled, the trace marker highlights the data symbol bits for the highlighted symbol and the marker readout provides the symbol number and its decimal value.

To make the table easier to read, the data bits are shown in groupings of eight characters followed by a space. The characters can represent a binary digit or a hexadecimal digit as specified by the Symbol Table Format parameter. The number to the left of each row indicate either the bit or symbol offset position depending the symbol table format as described below:

Binary Format: The symbol data bit format is binary and each character represents a binary digit. The number to the left of each row indicates the bit offset of the first bit in the row.

Hexadecimal Format: The symbol data bit format is hexadecimal and each character represents a hexadecimal digit. The number to the left of each row indicate the symbol offset of the first symbol in the row.

There must be at least 4 bits/symbol to use the hexadecimal format, that is, symbols that have less than 4 bits/symbol will only be displayed in binary format regardless of the Symbol Table Format setting.

The following Tips will help you to use the Symbol Table:

The symbol data bits can be viewed in either binary or hexadecimal format, see Symbol Table.
The measurement interval and offset determines the number of symbols (in chips) shown in the table. However, the table only shows PSDU payload data symbols, never preamble or header symbols.
Here's an easy way to identify symbol bits and their corresponding symbol points in the constellation diagram: Display the constellation diagram in one grid and the symbol table in another. Then turn on the markers for both displays and enable marker coupling. When the marker is placed on a point in the constellation diagram, the VSA highlights the corresponding symbol bits in the symbol table.
Marker Movement:The keyboard arrow keys or the mouse wheel can be used to move the marker from one symbol to the next. The Marker Position - X Position parameter can be used to move the marker to a specific symbol location.

Error Summary Data

The upper section of this display shows the modulation quality error data results and PLCP Header information for 802.11b/g DSSS/CCK/PBCC demodulation. Go to the Error Summary Data (802.11b/g DSSS/CCK/PBCC) topic for information about 802.11b/g DSSS/CCK/PBCC modulation Error Summary results.