LOG SWEEP for Harmonic extraction - Home Theater Forum and Systems - HomeTheaterShack.com

Old 01-15-14, 04:42 PM Thread Starter
New Member

Join Date: Oct 2012
Posts: 2
LOG SWEEP for Harmonic extraction

Hi,

A little question about the log sweep equation used in REW.

following the Farina deconvolution to extract Hn.

delta t between H2 and main impulse is done by:
delta t=T.(ln(N)/(ln(f1/f2)
N=order of harmonic,f1 end,f2 start,T lenght of sweep in sec.

for a 20 to 20KHz,5.9 seconds sweep:
H2 is 600ms before impulse (according Farina equ.)

in REW,the same sweep gives 340 ms between H2 and impulse.

is it a non standard log sweep ?

Thierry.

Last edited by thierry38; 01-15-14 at 05:02 PM. Reason: picture error
thierry38 is offline

Old 01-16-14, 04:28 PM
REW Author

John

Join Date: Apr 2006
Location: UK
Posts: 6,296
Re: LOG SWEEP for Harmonic extraction

The overall measurement time REW displays includes silent periods at the start and end of the sweep, the duration of the sweep itself is about 1.1s less. The picture is a little more complicated if the selected start frequency is below 10 Hz, in that case REW actually starts the sweep at DC with an initial linear sweep to approx 10 Hz and then transitions to a log sweep from there, to avoid spending a disproportionate time at very low frequencies.
JohnM is offline
Old 01-18-14, 01:09 AM Thread Starter
New Member

Join Date: Oct 2012
Posts: 2
Re: LOG SWEEP for Harmonic extraction

thanks for the explanation.

Thierry.
thierry38 is offline

 Bookmarks

 Tags extraction , harmonic , log , sweep

Message:
Options

## Register Now

Random Question
Random Question #2

User Name:
OR

## Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.