The input to this block is a baseband representation of the modulated signal. The M-ary number parameter, M, is the size of the input alphabet. M must have the form 2K for some positive integer K. This block supports multi-h Modulation index.
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The input to this block is a baseband representation of the modulated signal. The M-ary number parameter, M, is the size of the input alphabet. M must have the form 2K for some positive integer K. This block supports multi-h Modulation index. When you set the Output type parameter to Bit, then the block produces groupings of K bits. Each grouping is called a binary word. In binary output mode, the block first maps each input symbol to an intermediate value as in the integer output mode.
Finally, the block maps each nonnegative integer to a binary word, using a mapping that depends on whether the Symbol set ordering parameter is set to Binary or Gray. This block accepts a scalar-valued or column vector input signal with a data type of single or double. 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 the Samples per symbol parameter value, and the input can be a column vector. When you set Output type to Bit, the output width is K times the number of input symbols. When you set Output type to Integer, the output width is the number of input symbols.
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 the Samples per symbol parameter value.
When you set Output type to Bit, the output width equals the number of bits per symbol. When you set Output type to Integer, the output is a scalar. Traceback Depth and Output Delays Internally, this block creates a trellis description of the modulation scheme and uses the Viterbi algorithm. The Traceback depth parameter, D, in this block is the number of trellis branches that the algorithm uses to construct each traceback path. D influences the output delay, which is the number of zero symbols that precede the first meaningful demodulated value in the output.
When you set the Rate options parameter to Enforce single-rate processing, then the delay consists of D zero symbols. The optimal Traceback depth parameter value is dependent on minimum squared Euclidean distance calculations.
Parameters The size of the alphabet. Output type Determines whether the output consists of integers or groups of bits. Symbol set ordering Determines how the block maps each integer to a group of output bits.
This field is active only when Output type is set to Bit. The default is 0. The value of this property must be a real, nonnegative scalar or column vector. Phase offset rad The initial phase of the modulated waveform. Samples per symbol The number of input samples that represent each modulated symbol, which must be a positive integer. Rate options Select the rate processing method for the block. Enforce single-rate processing — When you select this option, the input and output signals have the same port sample time.
The block implements the rate change by making a size change at the output when compared to the input. The output width is the number of symbols which is given by dividing the input length by the Samples per symbol parameter value when the Output type parameter is set to Integer. Allow multirate processing — When you select this option, the input and output signals have different port sample times.
The output period is the same as the symbol period and equals the product of the input period and the Samples per symbol parameter value. Output datatype The output data type can be boolean, int8, int16, int32, or double. Supported Data Types.
The output is a baseband representation of the modulated signal. To modulate a signal using the continuous phase frequency shift keying method: Define and set up your CPFSK modulator object. See Construction. Call step to modulate the signal according to the properties of comm. The behavior of step is specific to each object in the toolbox. This object modulates the input signal using the continuous phase frequency shift keying CPFSK modulation method.
Continuous phase modulation
Phase memory[ edit ] Each symbol is modulated by gradually changing the phase of the carrier from the starting value to the final value, over the symbol duration. The modulation and demodulation of CPM is complicated by the fact that the initial phase of each symbol is determined by the cumulative total phase of all previous transmitted symbols, which is known as the phase memory. Therefore, the optimal receiver cannot make decisions on any isolated symbol without taking the entire sequence of transmitted symbols into account. Although this linear phase trajectory is continuous, it is not smooth since the derivative of the phase is not continuous.