Communications Blockset

Calculating the Error Rate

The Error Rate Calculation block, in the Comm Sinks library, compares the decoded bits to the original source bits. The output of the Error Rate Calculation block is a three-element vector containing the calculated bit error rate (BER), the number of errors observed, and the number of bits processed.

In the mask for this block, the Receive delay parameter is set to 96, because the Traceback depth value of 96 in the Viterbi Decoder block creates a delay of 96. If there were other blocks in the model that created delays, the Receive delay would equal the sum of all the delays.

BER simulations typically run until a minimum number of errors have occurred, or until the simulation processes a maximum number of bits. The Error Rate Calculation block uses its Stop simulation mode to set these limits and to control the duration of the simulation.

Viterbi Decoding

Evaluating Results