How would I convert the plots on ezCon from ezRA (Easy Radio Astronomy Software written by Ted Cline) into dB?

In ezRA’s ezCon, the plotted values are usually displayed in the raw linear units from the processed data files. If you want to express them in decibels (dB), the conversion depends on what the plotted quantity represents.

If the plot represents power:

dB = 10 * log10(P / P0)

where:

P  = measured power
P0 = reference power

If the plot represents voltage, signal amplitude, or FFT magnitude:

dB = 20 * log10(V / V0)

where:

V  = measured voltage or amplitude
V0 = reference voltage or amplitude

For typical radio astronomy continuum data, it is common to normalize the strongest signal to 0 dB:

dB = 10 * log10(S / Smax)

where:

S    = signal value
Smax = maximum signal value

Example:

S    = 1500
Smax = 5000

dB = 10 * log10(1500 / 5000)
   = 10 * log10(0.3)
   = -5.23 dB

As far as I know, ezCon does not have an option to automatically display continuum plots in dB. The usual procedure is:

1. Export the processed data from ezCon.
2. Load the data into Python, Excel, LibreOffice Calc, GNU Octave, or similar software.
3. Apply the logarithmic conversion.
4. Replot the data.

Python example:

import numpy as np

signal = np.loadtxt("ezConOutput.txt")

signal_db = 10 * np.log10(signal / np.max(signal))

For interferometer fringe data, continuum drift scans, and HI spectra, the best choice of reference level differs.