# Thread: Urgent-Unit Conversion- dBmV to dB

1. ## Urgent-Unit Conversion- dBmV to dB

How to convert from dBmV to dB?

2. Originally Posted by wence
How to convert from dBmV to dB?
Not enough information a dB is always relative to some reference
unit, 1 dBmV is 1 dB re 1mV, so to do a conversion we need to know
the new reference unit.

A non referenced dB measurement can be used for a gain but then
the unstated reference unit is the input.

RonL

3. Hi read the dBmV value (-70) from the spectrum analyzer. Do you mean i need a reference voltage or a reference input voltage, only then i can calculate the dB value?

4. Originally Posted by wence
Hi read the dBmV value (-70) from the spectrum analyzer. Do you mean i need a reference voltage or a reference input voltage, only then i can calculate the dB value?
This is difficult to explain without a better idea of exactly what you
are doing. But I spspect there is a sensitivity figure that goes with
your apparatus, which gives mV per unit of input, which should provide
the conversion factor.

RonL