RadioProcessor
Acquisition Parameters
The RadioProcessor performs quadrature signal detection, as shown in Figure 8 below. The incoming RF
signal, as captured by the ADC, is multiplied by the internal cos and sin signals to form the real and imaginary
signal channels respectively. These channels are then filtered and decimated to produce a baseband signal,
which can optionally be averaged with previous scans, and is then stored in the internal RAM.
Basic acquisition parameters that need to be set are the desired spectral width of the stored baseband
data, the number of points to capture, and the number of scans that will be performed. Based on these values,
the driver will set the internal acquisition and filtering parameters appropriately. This method of setting up the
acquisition hardware should suffice for many if not most applications. Complete control over all filtering
parameters is possible however, and users wishing to take advantage of this should contact SpinCore
Technologies.
Spectral width:
This is the bandwidth of the captured baseband (i.e., after quadrature detection) data.
Number of points:
Number of complex baseband (FID) points to capture. This is typically set to the
maximum number of points, although smaller numbers may be used if a lesser number of points is sufficient.
Number of scans:
Number of scans that are intended to be taken. The actual number of scans is
determined by the number of times the
trigger_scan
bit is enabled in the pulse program, but the maximum
number of scans that will be performed needs to be specified here so that the acquisition system can be setup
to avoid overflows.
Relevant spinapi functions:
pb_set_num_points()
pb_setup_filters()
NOTE:
To bypass the Digital Quadrature Detection use the spinapi function:
pb_get_data_direct()
2020-10-07
18
www.spincore.com
Figure 8:
Quadrature detection block diagram. The incoming analog signal is digitized and mixed with
the receiver cosine and sine waveforms to create the real and imaginary channels. Those channels are
then filtered and stored in on chip memory for the user to read back. The RadioProcessor's agile control
system allows for all aspects of the data acquisition to be user programmable.
Signal
Averaging
and
Storage
Filtering
and
Decimation
Real Channel
ADC
DDS
cos
sin
Tx
Filtering
and
Decimation
Imaginary Channel
CYCLOPS
Control
Incoming
Analog
Signal
To Tx Output
Channel
