MT Generate CPM Synchronization Parameters (bit array)

Generates synchronization parameters for CPM demodulation using a synchronization sequence directly represented by the sync bits array. The generated synchronization parameters cluster avoids phase ambiguity at the demodulator, thus allowing recovery of the actual message bits.

1378

Inputs/Outputs

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CPM system parameters

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

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samples per symbol

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

Note The demodulation and detector nodes use timing recovery, which is optimized for four or more samples per symbol.

Default value: 16

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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 value: Empty array

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sync bits

An array of synchronization bits used to generate the CPM synchronization parameter cluster. For example, if you specify a preamble word of 1111 1111 1111 1110 for symbol synchronization, you can wire a 16-bit array with the above entries to the sync bits parameter. For reliable symbol synchronization, specify an array of length (10 × bits per symbol).

Note To prevent false synchronization, select a bit pattern with low correlation to nonsynchronized portions of the data stream.

Default value: 0

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Default value: No error

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expected sync location

The expected location of the synchronization parameters in symbols. Set this value to -1 to search the entire waveform for the synchronization symbols.

Default value: -1

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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 value: 10

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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 value: 0

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CPM synchronization parameters

Synchronization parameters to pass to the demodulation node.

If the synchronization parameter passed to the demodulation node is left empty, the constellation of the demodulated waveform has a 90° carrier phase ambiguity for two-dimensional modulation schemes (QAM, QPSK, and higher order PSK) and a 180° carrier phase ambiguity for one-dimensional modulation schemes (PAM/ASK/BPSK).

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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.

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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.

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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 value: 10

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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 value: 0

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior