Lecture 28 - Engineer’s Computation Pad [\10.311E Dam-oz...

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Unformatted text preview: Engineer’s Computation Pad [\10.311E Dam-oz pmwr 77mg :44 DP? FM’W erorm Mwafigpflgflfflg H (Ja‘)§fmm p42- Mum— M N “Na )1 KAt=Zoly$ tAi- figuyflrnfé $414724 g, HQJJWJW (e; «4 v 140;.) (M 7 "a Tara/7L;S " "2‘:n<y,~‘; (5 {CW e ‘P(ot AJAQQ M; 5 - w E?" (fee/rm 5" Q: .. - M— fSW/e’ you”; N"‘°O°F°’\Uf5 Tawov at = 20 m5 at: 20/45 50H}- <——> W090 94779444 we 474(44ch ou/v Rafa/gel PW Wad/t? =5m5?‘ Z1 0-! tof~6.Wm1/o bffeyé'dm H(J+\) weqég/b‘jm 4‘4 7+ QVM7 4 “aka/“45 Fain/T5 W m/Wagfix 179W] "‘_ s 4 Ma bye oénuz MM, 577% 79¢ Max 4,5 WMJ. TMM/gzfi a V” FFW we rig; /3¢ur/f# aw} \Tzzcms / fidu/fl fies/W (AK-~— 50H?) 4 2ykrnc & 1mm 3— z ‘11 § K‘ \ 'er—lz _ -r. ‘__§:£M_m ffifl/g/‘m/m 'Avu /% d» 4M5 '3'-‘~.7 f1] 7 F lii‘igii‘iecr’s Cmnputa‘tion Pad No. l l V-W-v #2? [Jane M W41 h‘leée/Auk (Afi— A7>3+e19 {AH/d] fl-i pseuaéo ‘WM flag/“75% biz‘ Wu (PFM) WW 40w; jasmé/e I'S Md“ 0/3, férfm/fi 4: W 44%. We will use an m—sequence generator that is based on a 15—stage shift register for simulating a ran- dom data sequence. See the block diagram for the configuration of the xxx-sequence generator. The clock frequency is 1 MHz, which yields abit duration of 1 us. The period of the waveform is (215—1) 115 = 32.767 ms, thus the repetition frequency is approximately 30.5 Hz. BE! 15 Stage PN Generator -1+-1+1+-1+1+1+-1 -1 71M, MMDQW‘ 507% iii flLS Ms M meég ' 1%AJW‘WK%MM AXX' W W S/Lijizr” Mm (‘ZV‘93I~W’> «‘31me 7/6/43 7%! [\mQu/QL W, C I 1 Pa winter’s Computation 1 l LG enl- “Maximum-Num- can 11m: to nu Yime (rm) m.e«uoou«ic.eo‘m fllillflf 26-5 Impulse response of a loudspeaker measured at a distance of 1 m, with a single reflect ing surface nearby. (Courtesy of Doug Plumb, AcoustiSoft.) Impulse response of a loudspeaker measured at a distance of 3 m, with multiple reflec- tions. (Courtesy of Doug Plumb, AcoustiSqft.) l an. WIMowzaI-dmummmu Och Wlnflw:Ilnhnun-Hnrflu a.“ Time: 2 m- an. Tin-u: 2 m- - Frequency response of a loudspeaker measured at a distance of 1 m, with a single Frequency response of a loudspeaker measured at a distance of 1 m, with minimal ' reflections. (Courtesy of Doug Plumb, AcoustiSaft.) fllillfll 25-5 ' Frequency response of a loudspeaker measured at a distance of 3 n1 reflections. (Courtesy of Doug Plumb, AcausfiSoft.) , with multiple P I “r Q J 0 m p uta'i: i o n sllE C Engim:er"- N :1: . E o :r 8 a HlillilE 25-1 Frequency offset Time delay The basic principles of Heyser’s time-delay spectrometry measurements. The outgoing signal is swept linearly from A to B. After a delay appropriate to select out the reflec- tion desired, the receiver is swept from C to D. Only energy from the desired reflection is accepted; the receiver is detuned to all others. Left Ref Ch Impulse Response HEIIHE 28-2 Right Test Ch MLS test signal saved in memory loudspeaker microphone loudspeaker & environment Fast ‘FHT applied to Hadamam recorded data Transform Impulse response saved a???“ in buffer for path reference p 8. measurement channels for post processing. Block diagram of ETF 5’s impulse response measurement methodology. (Courtesy of Doug Plumb, AcoustiSoft.) #28 i, 5’ Impulse response Frequency response + delayed curves from later portions of the impulse response. applied gate gated response foun'er transform f l [i I! ll E 2 Ii -1 R Block diagram of Er F 5’s time slice frequency response computation methodology. (Cour- tesy of Doug Plumb, AcousfiSofl.) Onto Vllndowzalackmlmfllwh XI! 0“ SPL act- 11m: no .11. am mmm-m-H-nk L .MMICF mm:nm IIIllllllflllil A - ‘ -- - . v I...“ V .II IIIIIIIIIIIIIIIIHMEIIIWI IIIIIIIIIITIIIIIIII T I r 74 - lell (‘8) IIllllllllllllllllllllllllll llllllllllllllllllllllllllll IIIIIIIIIIIIIIIIIIIII Frequency (Hz) www.meoufllc.eorn Hfillflt 26-13 fllillflf 26-11 Low-frequency response measurement, showing frequency response and different time intervals ("time slices”). Resonances can be identified as peaks that appear every time slice, with varying level. Peaks that do not vary in level can be assumed to be noise. (Courtesy of Doug Plumb, AcaustiSofi.) One-third octave frequency response measurement, with a 20-ms gate. (Courtesy of Doug Plumb, Acousthafi.) ...
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This note was uploaded on 02/08/2011 for the course EEL 4930 taught by Professor Staff during the Spring '08 term at University of Florida.

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Lecture 28 - Engineer’s Computation Pad [\10.311E Dam-oz...

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