Python: FIR Filter Box

Example Python script to implement the FIR Filter Box

# pymoku example: Basic FIR Filter Box
#
# This example demonstrates how to run the FIR Filter Box and configure its
# individual filter channel coefficients.
#
# (c) 2019 Liquid Instruments Pty. Ltd.
#

from pymoku import Moku
from pymoku.instruments import FIRFilter

# The following two example arrays are simple rectangular FIR kernels with 50
# and 400 taps respectively. A rectangular kernel produces a sinc shaped
# transfer function with width inversely proportional to the length of the
# kernel. FIR kernels must have a normalised power of <= 1.0, so the value of
# each tap is the inverse of the total number of taps.
filt_coeff1 = [1.0 / 50.0] * 50
filt_coeff2 = [1.0 / 400.0] * 400

# Connect to your Moku by its device name
# Alternatively, use Moku.get_by_serial('#####') or Moku('192.168.###.###')
m = Moku.get_by_name('Moku')

try:
i = m.deploy_or_connect(FIRFilter)

# Configure the Moku:Lab's frontend settings
i.set_frontend(1, fiftyr=True, atten=False, ac=False)
i.set_frontend(2, fiftyr=True, atten=False, ac=False)

# Load the coefficients for each FIR filter channel.
#
# The channel's decimation factor determines the filter sample rate (Fs)
# and the maximum number of filter kernel coefficients (N) for the channel.
# The defining equations are given by:
#
# 3 <= decimation_factor <= 10,
# Fs = 125 MHz / 2^decimation_factor,
# N = 2^(decimation_factor) * 29.
#
# To implement 50 FIR taps, N = 2^(3) * 29 = 232 > 50
i.set_filter(1, decimation_factor=3, filter_coefficients=filt_coeff1)
# To implement 400 FIR taps, N = 2^(4) * 29 = 464 > 400
i.set_filter(2, decimation_factor=4, filter_coefficients=filt_coeff2)

# Both channels have unity gain and no offsets
i.set_gains_offsets(1, input_gain=1.0, output_gain=1.0, input_offset=0,
output_offset=0)
i.set_gains_offsets(2, input_gain=1.0, output_gain=1.0, input_offset=0,
output_offset=0)

finally:
m.close()