[sdiy] Equation for converting V PP to dBm?

[Justin Owen]

>>On 2011-12-29, at 9:01 AM, Justin Owen wrote:

>> What I'm trying to do is plot the response curve of the 2164 based on the data sheet spec of -33mV/dB. I figure if I can convert V PP to dB I'll also have mV to V PP.

Thanks for all the input into this - much appreciated.

Based on the replies here and a reading of http://en.wikipedia.org/wiki/Decibel - this seems to do the job

GdB = 20log10(Vout/Vin)

20log10(10/10) = 0dB and 20log10(10/5) = 6dB "...an increase of 6 dB corresponds to approximately four times the power and twice the voltage..." Right?

For the purpose of comparing the response of one VCA against another in the comfort of my own home - is there any reason why I can't call a 10V PP sine from a given output '0dB' (Vin) and plot any gain/attenuation as +/-dB (Vout)?

If the 2164 is capable of a maximum of -100dB then if I (am able to...) measure 20log10(0.0001/10) = -100dB - can I accept that is indeed -100dB as referenced in the data sheet?

Assuming this all makes sense and that GdB = 20log10(Vout/Vin) = x ...is a suitable equation for my current task - has anyone got any advice on resolving

GdB = 20log10(y / Vin) = x - where I know the value of 'x' and need to calculate the value of 'y' - e.g. GdB = 20log10(y / Vin) = 40 ?

J

P.S. - I'm not ignoring the thorough workings that some of you were kind enough to offer up - just need to work through this one step at a time. Ta!