RadioProcessor
Tips on obtaining data using singlepulse_nmr
The ability of this program to capture usable data is highly dependent on entering the correct parameters
for a given NMR setup. It is expected that the user is familiar with how to best specify PULSE_TIME,
TRANS_TIME, TX_PHASE, SPECTROMETER_FREQUENCY, etc. Setting the SPECTRAL_WIDTH,
however, may not immediately be obvious.
If the signal is very short (on the order of microseconds), for example as in NMR with solid samples or with
inhomogeneous magnetic fields, there is ample room in the on board RAM to capture the entire signal with a
very large spectral width (1 MHz or more). Often this is the best approach, even if the signals are near DC
(i. e. near or at spectrometer frequency) and thus do not require a large spectral width to be represented. To
do this, the FIR filter can be bypassed with the BYPASS_FIR parameter to achieve the large spectral width.
This will result in signals being attenuated near the edge of the passband, but this will not matter since the
signal of interest is near DC.
For longer FID signals, where a smaller spectral width is more useful, the FIR filter may be bypassed as
well. The FIR filter is necessary only for very low spectral widths (on the order of several Hz) when a flat
response is needed over the entire spectrum. Please note that when the FIR is enabled, the spectral width
must be the ADC_FREQUENCY divided by some multiple of 8. If such a value is not specified, the spectral
width will be rounded appropriately. The FIR filter also adds an initial latency to any acquired data that is
dependent on the number of FIR coefficients. These initial points should be discarded. In general, lowering
the spectral width will reduce the noise in the signal.
The source code of the
singlepulse_nmr.c
program is included in the SpinAPI Examples and is well
commented. Users wishing to create custom programs may refer to this to get the details of how to control the
RadioProcessor.
Graphical User Interfaces
In addition to the Single Pulse NMR code included with SpinAPI, graphical user interfaces have been
created for use with MATLAB and LabVIEW. Please see Appendices III and IV for sample screenshots, or
visit the following links for further information.
http://www.spincore.com/support/RadioProcessor/MATLAB/
http://www.spincore.com/support/PBLV/RP.shtml
2020-10-07
15
www.spincore.com
