# Make your own Bode plot paper

The code for BodePaper.m is available at https://github.com/echeever/BodePlotGui

When making Bode plots one needs two pieces of semi-logarithmic paper, one for the magnitude plot and one for the phase.  The program described here, BodePaper.m, can be used to make paper.   Download it and save it so that MatLab can find it (from the Matlab menu you can go to File→Set Path and include the directory where you stored the BodePaper.m file.) . There is also a fine in the repository called BodeMagPaper.m that creates only a magnitude plot.

The syntax for calling is given by the function's help file.

>> help BodePaper

BodePaper is Matlab code to generate graph paper for Bode plots. It generates
two semilog graphs for making Bode plots. The top plot is for magnitude, the
units on the vertical axis is set to dB. The bottom plot shows phase. The
units on the phase plot can be radians or degrees, at the discretion of the
user. The default is degrees.

The correct calling syntax is:
BodePaper(om_lo, om_hi, dB_lo, dB_hi, ph_lo, ph_hi, UseRad)
om_lo the low end of the frequency scale. This can be either
rad/sec or Hz. No units are displayed on the graph.
om_hi the high end of the frequency scale.
dB_lo the bottom end of the dB scale.
dB_hi the top end of the dB scale.
ph_lo the bottom end of the phase scale.
ph_hi the top end of the phase scale.
UseRad an optional argument. If this argument is non-zero the units
on the phase plot are radians. If this argument is left off
or set to zero, the units are degrees.

To make paper that goes from 0.1 Hz to 100 Hz, with the magnitude scale going from -60 to 40 dB and the phase from -180 to 90 degrees, the function call would be

>> BodePaper(0.1,100,-60,40,-180,90)

and the paper looks like: To change the units on phase the function call would be:

 BodePaper(0.1,100,-60,40,-pi,pi/2,1)

and the paper now looks like this: References

© Copyright 2005 to 2019 Erik Cheever    This page may be freely used for educational purposes.

Erik Cheever       Department of Engineering         Swarthmore College