MT Generate QAM Synchronization Parameters (bit array)
- Updated2023-02-17
- 4 minute(s) read
MT Generate QAM Synchronization Parameters (bit array)
Generates synchronization parameters for QAM 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.
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Inputs/Outputs
QAM system parameters
Parameter values defining the QAM system. Wire the QAM system parameters cluster of MT Generate QAM System Parameters (M) or MT Generate QAM System Parameters (map) to this cluster. Do not alter the values.
samples per symbol
Number of samples per symbol in the modulated output complex waveform. For error-free operation, the samples per symbol value must be an even number.
Default value: 16
symbol map
An ordered array that maps each symbol to its desired coordinates in the complex plane. The number of QAM states in the array is 2N, where N is the number of bits per symbol. The vector length for the symbols farthest from the origin is 1.
sync bits
An array of synchronization bits used to generate the QAM synchronization parameters 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).
Default value: 0
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Default value: No error
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
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
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
QAM 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).
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 array from the specified synchronization bits or synchronization numbers.
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
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
error out
Error information.
The node produces this output according to standard error behavior.