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MT MLSE Demapper (CPM) (G Dataflow)

Last Modified: January 9, 2017

Maps a CPM-modulated complex baseband waveform to an output bit stream using maximum likelihood sequence estimation (MLSE). The node expects the input complex waveform to be synchronized, in every aspect, to the receiver.


This node assumes that the sample rate of the input complex waveform is exactly samples per symbol × the symbol rate. If this relationship does not apply to your application, use MT Resample (Complex Cluster) to resample the waveform to the desired sample rate.


input complex waveform

The modulated complex baseband waveform data.



Trigger (start) time of the Y array.

Default: 0.0



Time interval between data points in the Y array.

Default: 1.0



The complex-valued signal-only baseband modulated waveform. The real and imaginary parts of this complex data array correspond to the in-phase (I) and quadrature-phase (Q) data, respectively.


CPM system parameters

Parameter values defining the CPM system. Wire the CPM system parameters cluster from MT Generate CPM System Parameters (M) or MT Generate CPM System Parameters (map) to this cluster. Do not alter the values.


samples per symbol

An even, positive number of samples dedicated to each symbol. Multiply this value by the symbol rate to determine the sample rate.

Default: 16


symbol map

A two-dimensional array of desired frequency deviations. Each column corresponds to a symbol, with the binary representation of the column index being the mapped bit-representation of the symbol. Each row corresponds to a modulation index in the order in which it appears in the modulation index, h(i) parameter of MT Generate CPM System Parameters (M) or MT Generate CPM System Parameters (map).

Default: Empty array


pulse shaping filter coefficients

An ordered array containing the coefficients of the pulse-shaping filter used during the modulation of the received waveform.


CPM MLSE settings

CPM MLSE settings.


traceback depth

Number of trellis stages to trace back during the Viterbi decoding process. The output bit sequence is delayed, in time, by this amount with respect to the incoming waveform.

Default: 15


h(i) start index

Index of the array of modulation indexes, h(i), corresponding to the modulation index of the first symbol. The node ignores this parameter if the reset? parameter is set to FALSE.

Default: 0


block size

Length, in symbols, of a block of the received waveform, used during block-wise processing. At the beginning of each block, the node resets the Viterbi decoding process. Each block overlaps with the previous block for a number of symbols equal to traceback depth. To enable block-wise processing, set this value to a positive integer greater than the traceback depth.

Default: -1


error in

Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

Default: no error



A Boolean that determines whether the node continues demodulating using the previous iteration states.

TRUE Restarts the demodulator. The node resets on the first call and when reset? is set to TRUE.
FALSE Continues demodulating using the previous iteration states.

Default: TRUE


output bit stream

The demapped information bit stream.


error out

Error information. The node produces this output according to standard error behavior.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

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