MT Compensate Sample Clock Frequency Error (QAM)
- Updated2023-02-17
- 4 minute(s) read
MT Compensate Sample Clock Frequency Error (QAM)
Estimates and corrects sample clock frequency offset, which is the difference between the sample clocks at the D/A converter of the transmitting DUT and digitizer. Use this node before MT Demodulate QAM. You might need to call this node multiple times for high values of sample clock offsets.
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Inputs/Outputs
input complex waveform
The modulated complex baseband waveform data.
t0
Trigger (start) time of the Y array.
Default value: 0.0
dt
Time interval between data points in the Y array.
Default value: 1.0
Y
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.
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 value: 16
matched filter coefficients
An ordered array containing the desired matched filter coefficients. Wire the matched filter coefficients parameter of MT Generate Filter Coefficients to this parameter. When generating the filter coefficients, ensure that the value of the matched samples per symbol parameter of MT Generate Filter Coefficients is equal to the value of the samples per symbol input.
clock phase computation window (symbols)
Length of the symbol window to use in computation of the symbol timing offset in each iteration. Use a higher value to improve the accuracy of the estimated clock phase and sample clock frequency. Use a smaller value if the expected sample clock offset is large.
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
output complex waveform
The baseband complex waveform corrected for the estimated sample clock frequency offset.
t0
Trigger (start) time of the Y array.
Default value: 0
dt
Time interval between data values in the Y array.
Default value: 1.0
Y
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.
sample clock frequency error
The estimated offset, in parts per million (ppm), as the difference between the sample clock frequencies at the generator and analyzer. For example, if the symbol rate set at the analyzer is 30 ppm more than the corresponding symbol rate set at the generator, the parameter returns a value of -30 ppm.
error out
Error information.
The node produces this output according to standard error behavior.