Name | Type | Range |
---|---|---|

Block Diagram | System Diagram | N/A |

BER/SER Meter | System BER/SER Meter | N/A |

Modulation Type | List of options | N/A |

Statistic Type | List of options | N/A |

The measurement plots a theoretical QAM bit or symbol error
probability along the y-axis and the swept variable (typically
E_{b}/N_{0} or E_{s}/N_{0}) along the x-axis. The
y-axis should normally be set to use log scaling.

The measurement generates a reference curve based on the type
and settings of the meter block selected in the BER/SER
Meter setting. If the BER/SER Meter parameter
is set to "Auto", the measurement will
compute the bit error probabilities P_{b} for BER
meters and symbol error probabilities P_{s} for
SER meters. Values for P_{b} or P_{s} are
calculated for each power value specified in the meter's
SWPTV parameter.

When M is an even power of 2 (M=2^{k}, k
is even) the following equations are used [1]:

where Q(x) is the Gaussian integral or Q-function:

and is approximated numerically, E_{s} is
the average symbol energy, N_{0} is the
noise power spectral density and M is the number
of signal levels.

For other values of M an approximate upper bound is calculated from [1]:

The measurement computes bit error probabilities from the symbol error probabilities using the following approximation [1]:

This approximation assumes Gray coded square QAM constellations, which is not realizable for all values of M.

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