I know it's associated with digital overload power, but I'm looking for a more precise definition; something like: 0 dBOV = 10*log P1/Pref, where Pref is the maximum RMS SINEWAVE power possible. The basic question is this: is it RMS power or peak power, and if it is RMS power, for what type of waveform? -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124

# Definition of dBOV

Started by ●May 10, 2004

Reply by ●May 10, 20042004-05-10

Randy Yates <randy.yates@sonyericsson.com> writes:> 0 dBOV = 10*log P1/Pref,Sorry, that should read dBOV = 10*log P1/Pref, -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124

Reply by ●May 10, 20042004-05-10

Randy Yates wrote:> I know it's associated with digital overload power, but > I'm looking for a more precise definition; something like: > > 0 dBOV = 10*log P1/Pref, > > where Pref is the maximum RMS SINEWAVE power possible. The > basic question is this: is it RMS power or peak power, and > if it is RMS power, for what type of waveform?No answer, just another question. dBov is relative to system overload, but I see it quoted as large positive numbers. Is there an implicit minus sign? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������

Reply by ●May 10, 20042004-05-10

Jerry Avins <jya@ieee.org> writes:> Randy Yates wrote: > >> I know it's associated with digital overload power, but >> I'm looking for a more precise definition; something like: >> 0 dBOV = 10*log P1/Pref, where Pref is the maximum RMS SINEWAVE >> power possible. The >> basic question is this: is it RMS power or peak power, and if it is >> RMS power, for what type of waveform? > > No answer, just another question. dBov is relative to system overload, > but I see it quoted as large positive numbers. Is there an implicit > minus sign?Not that I know of, Jerry. I've seen it as a negative number. -- % Randy Yates % "Maybe one day I'll feel her cold embrace, %% Fuquay-Varina, NC % and kiss her interface, %%% 919-577-9882 % til then, I'll leave her alone." %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO http://home.earthlink.net/~yatescr

Reply by ●May 11, 20042004-05-11

Randy Yates wrote:> Jerry Avins <jya@ieee.org> writes: > > >>Randy Yates wrote: >> >> >>>I know it's associated with digital overload power, but >>>I'm looking for a more precise definition; something like: >>>0 dBOV = 10*log P1/Pref, where Pref is the maximum RMS SINEWAVE >>>power possible. The >>>basic question is this: is it RMS power or peak power, and if it is >>>RMS power, for what type of waveform? >> >>No answer, just another question. dBov is relative to system overload, >>but I see it quoted as large positive numbers. Is there an implicit >>minus sign? > > > Not that I know of, Jerry. I've seen it as a negative number.Thanks. A quick look with Google confirms that. I guess I generalized from a very small sample. If I wanted a measure relative to overload, I'd define overload first. For DACs and ADCs, it's peak voltage. It seems reasonable (but hardly proof) that dBov is defined that way. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������

Reply by ●May 11, 20042004-05-11

Jerry Avins <jya@ieee.org> writes:> [...] > If I wanted a measure relative to overload, I'd define overload first. > For DACs and ADCs, it's peak voltage. It seems reasonable (but hardly > proof) that dBov is defined that way.I would say it's clear what an overload is (something exceeding full-scale), but since there are a number of ways to specify it. The question is then "Which way was it specified" (e.g., "full-scale RMS sine wave" or "full-scale square wave power" are two most-probable methods). By the way, an SEMC colleague believes it is the full-scale RMS sinewave power method. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA randy.yates@sonyericsson.com, 919-472-1124

Reply by ●May 11, 20042004-05-11

Randy Yates wrote:> Jerry Avins <jya@ieee.org> writes: > >>[...] >>If I wanted a measure relative to overload, I'd define overload first. >>For DACs and ADCs, it's peak voltage. It seems reasonable (but hardly >>proof) that dBov is defined that way. > > > I would say it's clear what an overload is (something exceeding full-scale), > but since there are a number of ways to specify it. The question is then > "Which way was it specified" (e.g., "full-scale RMS sine wave" or "full-scale > square wave power" are two most-probable methods). > > By the way, an SEMC colleague believes it is the full-scale RMS sinewave > power method.Even analog amplifiers, as long as they have stiff power supplies and are not too heavily loaded, clip at some particular voltage. DACs clip at MAX_Int, etc. A*[sin(wt) + sin(3wt)] and A*[sin(wt) - sin(3wt)] have precisely the same RMS power, but the second will pass undistorted through a system that clips the first. That said, RMS sinewave power may indeed be the standard. I never got very far by taking for granted that the world is rational. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������

Reply by ●May 11, 20042004-05-11

Hi, I don't know about dBov, but perhaps it is similar to dBO, used in PCM (i.e. A-law and u-Law) telecoms. That is defined as 8 specific samples which will produce a 1kHz sine wave that is considered 0dBO. The clip point turns about to be about +3.14dBO for a sine wave. I would think it likely that dBov would be defined in a similar sine wave manner, but with the wave being considered 0dBov just below clip. Square wave are also a possibility, I guess, but engineers have a deep love of sine waves. :-) Regards, Steve Randy Yates <randy.yates@sonyericsson.com> wrote in message news:<xxpoeovne6i.fsf@usrts005.corpusers.net>...> Jerry Avins <jya@ieee.org> writes: > > [...] > > If I wanted a measure relative to overload, I'd define overload first. > > For DACs and ADCs, it's peak voltage. It seems reasonable (but hardly > > proof) that dBov is defined that way. > > I would say it's clear what an overload is (something exceeding full-scale), > but since there are a number of ways to specify it. The question is then > "Which way was it specified" (e.g., "full-scale RMS sine wave" or "full-scale > square wave power" are two most-probable methods). > > By the way, an SEMC colleague believes it is the full-scale RMS sinewave > power method.

Reply by ●May 12, 20042004-05-12

On Tue, 11 May 2004 13:55:40 -0400, Jerry Avins <jya@ieee.org> wrote:>A*[sin(wt) + sin(3wt)] and A*[sin(wt) - sin(3wt)] have >precisely the same RMS powerI could have sworn they have the same *average* power. Regards, Allan.

Reply by ●May 12, 20042004-05-12

Allan Herriman wrote:> On Tue, 11 May 2004 13:55:40 -0400, Jerry Avins <jya@ieee.org> wrote: > > > >>A*[sin(wt) + sin(3wt)] and A*[sin(wt) - sin(3wt)] have >>precisely the same RMS power > > > I could have sworn they have the same *average* power. > > Regards, > Allan.The total RMS power is the sum of the components' individual RMS powers. A component's RMS power is unchanged by changing its sign. I haven't (and won't) compute average power, but I guess you're right. I can see by inspection that the ratio of peak powers is about 5:8. How do we disagree? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������