# 1.343 Vrms = 2.555 dbV, how? using the digital analyzer HP3561

#### tuan.le007

Joined Nov 29, 2016
46
I have the hp 3561a dynamic signal analyzer.
using the function
LINEAR, I measured 1.343 Vrms
using LOG, I measured 2.555 dbV.
Can someone explain to me how this work?
formulas and calculations would help. I need to convert this in my code in order to measure 1.343 on the display.
It is showing 2.5555 dbV right now.

thanks

#### Papabravo

Joined Feb 24, 2006
13,724
$$20 \times log(\frac{1.343}{1})\;=\;2.56 \text dBV$$

#### crutschow

Joined Mar 14, 2008
24,963
dBV is the voltage in dB relative to a 1V reference.
That's shown in the equation in PB's post.

To convert dBv to volts, you use the inverse equation:
10^(2.56dBV/20)= 1.343V