Example Python script to implement the Spectrum Analyzer (plotting)

This example Python script shows how to setup Moku:Lab's Spectrum Analyzer instrument and how to plot the data in real time. This example is not compatible with Moku:Go or Moku:Pro.

#
# pymoku example: Plotting Spectrum Analyzer
#
# This example demonstrates how you can configure the Spectrum Analyzer
# instrument and plot its spectrum data in real-time. It also shows how
# you can use its embedded signal generator to generate a sweep and single
# frequency waveform on the output channels.
#
# (c) 2019 Liquid Instruments Pty. Ltd.
#
from pymoku import Moku
from pymoku.instruments import SpectrumAnalyzer
import logging

import matplotlib.pyplot as plt
from matplotlib.ticker import FuncFormatter

logging.basicConfig(format='%(asctime)s:%(name)s:%(levelname)s::%(message)s')
logging.getLogger('pymoku').setLevel(logging.INFO)

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

# Use dBm scaling on the y-axis
dbm = True

try:
 i = m.deploy_or_connect(SpectrumAnalyzer)

 # Set spectrum analyzer configuration
 i.set_defaults()
 i.set_dbmscale(dbm)
 i.set_span(0, 70e6)
 i.set_rbw() # Auto-mode

 # Set up the embedded signal generator
 i.gen_sinewave(1, 1.0, 0, sweep=True)
 i.gen_sinewave(2, 0.5, 20e6)

 # Configure ADC inputs
 i.set_frontend(1, fiftyr=True)
 i.set_frontend(2, fiftyr=True)

 # Set up basic plot configurations
 line1, = plt.plot([])
 line2, = plt.plot([])
 plt.ion()
 plt.show()
 plt.grid(b=True)
 if(dbm):
 plt.ylim([-200, 100])
 else:
 plt.ylim([-0.5, 1.0])
 plt.autoscale(axis='x', tight=True)

 # Get an initial frame of data to set any frame-specific plot parameters
 frame = i.get_realtime_data()

 # Format the x-axis as a frequency scale
 ax = plt.gca()
 ax.xaxis.set_major_formatter(FuncFormatter(frame.get_xaxis_fmt))
 ax.yaxis.set_major_formatter(FuncFormatter(frame.get_yaxis_fmt))
 ax.fmt_xdata = frame.get_xcoord_fmt
 ax.fmt_ydata = frame.get_ycoord_fmt

 # Get and update the plot with new data
 while True:
 frame = i.get_realtime_data()
 plt.pause(0.001)

 # Set the frame data for each channel plot
 line1.set_ydata(frame.ch1)
 line2.set_ydata(frame.ch2)
 # Frequency axis shouldn't change, but to be sure
 line1.set_xdata(frame.frequency)
 line2.set_xdata(frame.frequency)
 # Ensure the frequency axis is a tight fit
 ax.relim()
 ax.autoscale_view()

 # Redraw the lines
 plt.draw()
finally:
 m.close()