VU question pop quiz

[Tim Ressel]

To clarify:

For voltage ratios, 20 * log (V2/V1), 6 dB down is half the voltage
for power ratios, 10 * log (P2/P1), 3 dB down is half the power

0 dBm refers to 1mW into a certain impedence like 50 or 600 ohms, is a power
measurement i.e. +3 dB = 2mW

0 dBV would be a voltage measurement with some reference like 1Vrms=0dBV. +6 dB
= 2Vrms.

Accoring to the Recording Engineer's Handbook (I was just informed), VU is a
power measurement, with 0 dBm = 1mW into 600 ohms.



Tim Ressel--Compliance Engineer
Hewlett-Packard
Verifone Division
916-630-2541  
tim_r1 at verifone.com                     



-----Original Message-----
From: Peter Blackett [mailto:dragonser at clara.net]
Sent: Wednesday, February 23, 2000 1:21 PM
To: Tim Ressel
Subject: Re: VU question pop quiz


DEar Tim Ressel wrote:
VU meters display voltage , and there are two standards [or more ] for
what
 voltage = 0dB   .
I think -3dB is half ?
regards Peter 
confused in South London England