From: John Woodgate
Subject: Re: Psophometric Noise ?? how to measure ?
Date: Mon, 20 Jan 2003 17:42:10 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Mon, 20 Jan 2003 20:03:10 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Sagaert Johan
wrote (in <firstname.lastname@example.org
e>) about 'Psophometric Noise ?? how to measure ?', on Mon, 20 Jan 2003:
>noisy question :
>If i have a signal and pass it trough a bandpass filter (ie 300-3400 hz) ,
>and then i use
>a true RMS meter to measure the result (for example 0dBm ) .
>Is it then true to say that the psophometric noise level is 85dBa
>(referenced to 3.16 pW) ?
No. Not if that 'a' in your very non-standard symbol 'dBa' means 'A-
weighted', which is nothing like psophometric weighting. Your
measurement is *unweighted, band-limited*.
Also, there are several different psophometric noise measurements, so
you need to define which one you mean. The ITU-R one, for example, uses
a quasi-peak meter, not true r.m.s.
0 dB(mW) is indeed 85 dB ref. 3.16 pW.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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