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MT Map CPM Symbols to Bits (G Dataflow)

Last Modified: January 9, 2017

Maps symbols comprised of CPM frequency deviations to an output bit stream based on the symbol map that you specify.

Programming Patterns
Use this node in conjunction with MT Matched Filter, MT Align to Ideal Symbols, MT Decimate Oversampled Waveform, and MT Calculate BER to perform waveform analysis on the modulated waveform.

The mapping of symbols to bits depends on the number of bits per symbol, which equals log 2 ( M ) with M representing the size of the modulation scheme. For example, in a 256-QAM system, 500 QAM symbols are mapped to ( 500 ) × log 2 ( 256 ) = 4000 m e s s a g e b i t s .



An array of frequency deviations for one-to-one mapping to the output bit stream.


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). To specify a prebuilt map, unbundle the symbol map element from the CPM system parameters cluster generated by MT Generate CPM System Parameters (M) or MT Generate CPM System Parameters (map).

Default: empty array


synchronization parameters

Parameter values describing the synchronization sequence and the range of bits over which to search for the sequence. Wire the CPM synchronization parameters cluster returned by MT Generate CPM Synchronization Parameters (bit array) or MT Generate CPM Synchronization Parameters (number array) to this cluster.


If the synchronization parameters cluster is not wired, the demodulator does not attempt to synchronize, and the constellation of the demodulated waveform has a carrier phase ambiguity.


expected sync location

The expected location of the first symbol of the sync sequence.

This value is an index to the input complex waveform. A value of -1 searches the entire input complex waveform and ignores the sync location uncertainty parameter.


sync sequence

The mapped symbol pattern. Although the data type is complex, only the real portion is used.

The real portion of the mapped symbols is the frequency deviation of the symbol value, and the imaginary portion is 0. To prevent false synchronization, configure this pattern so that there is a low probability of accidental correlation to nonsynchronized parts of the data stream. If this parameter is left empty, the signal is still demodulated.


sync location uncertainty

Number of symbols before or after the expected sync location where the first symbol of the sync sequence may be located. The node ignores this parameter if the expected sync location parameter is set to -1.

Default: 10


sync indent

Distance that the sync sequence is indented into the information block.

The distance is the number of demodulated symbols preceding the sync sequence. For example, a value of 10 indicates that the output bit stream consists of 10 data symbols, followed by the sync sequence, followed by the remaining data symbols.

Default: 0


error in

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

Default: no error


output bit stream

A bit stream with a one-to-one mapping to the input symbols based on the specified symbol map.


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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