Integer-Valued Signals and Binary-Valued Signals

When you set theOutput typeparameter toInteger,然后e block produces odd integers between -(M-1) and M-1.

When you set theOutput typeparameter toBit,然后e block produces groupings ofKbits. Each grouping is called a binaryword.

In binary output mode, the block first maps each input symbol to an intermediate value as in the integer output mode. The block then maps the odd integer k to the nonnegative integer (k+M-1)/2. Finally, the block maps each nonnegative integer to a binary word, using a mapping that depends on whether theSymbol set orderingparameter is set toBinaryorGray.

This block accepts a scalar-valued or column vector input signal with a data type ofsingleordouble.

Single-Rate Processing

In single-rate processing mode, the input and output signals have the same port sample time. The block implicitly implements the rate change by making a size change at the output when compared to the input. The input width must be an integer multiple of theSamples per symbolparameter value, and the input can be a column vector.

Multirate Processing

In multirate processing mode, the input and output signals have different port sample times. The input must be a scalar. The output symbol time is the product of the input sample time and theSamples per symbolparameter value.

Traceback Depth and Output Delays

Internally, this block creates a trellis description of the modulation scheme and uses the Viterbi algorithm. TheTraceback depthparameter,D, in this block is the number of trellis branches that the algorithm uses to construct each traceback path.Dinfluences the output delay, which is the number of zero symbols that precede the first meaningful demodulated value in the output.

The optimalTraceback depthparameter value is dependent on minimum squared Euclidean distance calculations. Alternatively, a typical value, dependent on the number of states, can be chosen using the “five-times-the-constraint-length” rule, which corresponds to 5·log2(numStates).

For the definition of the number of states, seeCPM Demodulator BasebandHelp page.