Convert Vpk-Vpp-Vrms-dBV-dBu-mW-dBm

This is a conversion utility for some common units used for expression of sinusoidal signal voltage.

SVN:

The calculator does not do a lot of error checking, if you enter nonsense, it will produce nonsense. NaN means not a number, check the input values. Specify a load resistance, and enter a value in any one of the 'convert' cells and press Enter. Input values can be in exponential notation (eg 1e-6 for 1 micro Volt).

The load resistance is used for power calculations (mW, dBm).

Remember that the terminal voltage of an idealised source with a matched load is half that, or 6dB lower than with no load.

FAQ

Why doesn't the calculator do dBfs?

dBfs means dB wrt full scale and is used usually to express a signal level in a digital system or record referenced to the maximum possible digitised amplitude. It is not an absolute measure than can be converted universally to voltage, but can be converted to voltage knowing the voltage equivalent of 'full scale'.

Is dBu the same as dB wrt 1 micro Volt (dBµV)?

In expressing sensitivity of radio receivers, signal levels are often expressed in dB relative to 1 micro Volt (µV). There is a common practice to write this as dBuV rather than dBµV due to shortcomings of the character set in some contexts. dBµV may be qualified as 'emf' meaning it is the unloaded voltage of the source, otherwise it should be taken as the terminal voltage of a source terminated in a matched load.

dBu is often used to express signal levels in audio systems, and it means the signal level in dB relative to the voltage in 600Ω for 1mW (0.7746Vrms). dBu were often read directly from older multimeters with a dB scale, calibrated to read 0dB at 0.7746Vrms. Note that:

• dBu does not specify a power, but a voltage measured with a high impedance meter relative to the voltage in 600Ω for 1mW; and
• it usually assumes that the source is unloaded.

dBu and dBµV are not the same thing, 0dBu is equivalent to 117.78dBµV emf.

How can I convert -12dBµV to mW?

Convert -12dBµV to dBV by subtracting 120 for -132dBµV and using the calculator to obtain -118.99dBm.

To convert dBV to dBµV, add 120, so -105dBm is -118.01dBV using the calculator or add 120, 1.99dBµV.

Links

Changes

© Copyright: Owen Duffy 1995, 2021. All rights reserved. Disclaimer.