MT Generate MSK Synchronization Parameters (bit array)
- Updated2023-02-17
- 5 minute(s) read
MT Generate MSK Synchronization Parameters (bit array)
Generates synchronization parameters for MSK demodulation using a synchronization sequence directly represented by the sync bits input 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
MSK system parameters
Parameter values defining the MSK system. Wire the MSK system parameters cluster returned by MT Generate MSK System Parameters to this cluster. Do not alter the values.
differential encoding enable
A value that indicates whether the bit sequence is differentially encoded.
| disable |
Disables bit sequence encoding. |
| enable |
Enables bit sequence encoding. |
Default value: enable
samples per symbol
Number of samples per symbol in the modulated output complex waveform.
For error-free operation, the samples per symbol must be an even number. Applying Carson's rule for MSK modulation [peak frequency deviation = 0.25 × symbol rate (Hz)], the 98% MSK bandwidth is given by 0.5 × (1 + r) × symbol rate + peak frequency deviation, where 0 < r ≤ 1 is the filter parameter. To satisfy Nyquist criterion, a good guideline is given by samples per symbol = 2 × ceil(1.5 × bandwidth/symbol rate) to obtain 3× oversampling.
Default value: 16
sync bits
An array of synchronization bits used to generate the MSK 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
symbol rate
The desired symbol rate, in hertz (Hz).
Default value: 1.0
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
MSK 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 pattern used to synchronize the bit stream. To prevent false synchronization, select this pattern such that there is a low probability of accidental correlation to nonsynchronized parts of the data stream. For MSK, the real portion of the mapped symbols is the frequency deviation of the symbol value, and the imaginary portion is 0. 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 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.