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Analog & DSP, FIR Electronic Filters - Frequency Devices

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   Filters, AF

An audio filter is a type of filter used for processing sound signals. Many types of filters exist for applications including graphic equalizers, synthesizers, sound effects, CD players and virtual reality systems.

In its simplest form, an audio filter is typically designed to pass some frequency regions through unattenuated while significantly attenuating others. In some applications, such as in the design of graphic equalizers or CD players, the filters are designed according to a set of objective criteria such as pass band, pass band attenuation, stop band, and stop band attenuation, where the pass bands are the frequency ranges for which audio is attenuated less than a specified maximum, and the stop bands are the frequency ranges for which the audio must be attenuated by a specified minimum.

In more complex cases, an audio filter can provide a feedback loop, which introduces resonance (ringing) alongside attenuation. Audio filters can also be designed to provide gain (boost) as well as attenuation.

In other applications, such as with synthesizers or sound effects, the aesthetic of the filter must be evaluated subjectively.

Audio filters can be implemented in analog circuitry as analog filters or in DSP code or computer software as digital filters.

Non-linear filters are also used in audio applications: for example, compressors, fuzz boxes, ring modulators.

Generically, the term 'audio filter' can be applied to mean anything which changes the timbre, harmonic content, pitch or waveform of an audio signal.



Platinum Partners
Frequency Devices, Inc.
Bronze Partners
Aeroflex Laboratories Inc
Allied Components International
Alpha Components
Amecon, Inc.
American Trans-Coil Corp.
Anatech Electronics, Inc.
Avens Signal Equipment Corp.
Betatronics, Inc.
Chesterfield Products, Inc.
Communication Coil Inc.
Compel Electronics Inc
Corning Frequency Control
Data Delay Devices
Electrocom Industries
Electrocube, Inc.
Electronic Specialists Inc.
Gennum Corporation
Hisonic, Inc.
Inductive Technologies
Integrated Microwave Corporation
Integration Assocs. Inc.
JMK, Inc.
Keytronics, Inc.
KR Electronics, Inc.
Krohn-Hite Corp.
LCR Electronics, Inc.
Linear Technology Corp.
Magnetico, Inc.
Mainstar Industries Limited
Marchand Electronics
Microtran Manufacturing Division
Netcom Inc.
Networks International Corp.
Parker Hannifin/Balston
Pico Electronics, Inc.
Precision Filters, Inc.
RFI Corp.
Rsm Sensitron Semiconductor
Shure Incorporated
Solar Electronics Company
Synetcom Digital Inc.
Thordarson Inc.
Thordarson Meissner Incorporated
TOA Electronics, Inc.
Toroid Corporation of Maryland
TTE, Incorporated
Analog & DSP, FIR Electronic Filters - Frequency Devices

 

Books
Handbook of Filter Synthesis
Anatol I. Zverev

Excerpt - page 21: "... to 5000. The higher these values are, the better the filter that can be designed. Figure ... frequency of the filter and Af is the bandwidth (passband ). For the same absolute bandwidth ..."
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Principles of Adaptive Filters and Self-learning Systems (Advanced Textbooks in Control and Signal Processing)
Anthony Zaknich

Excerpt - page 72: "... then computing the average of the squared output from the filter (Bendat and Piersol 1971). This ... 2.82 as the filter bandwidth Af approaches zero. Gx(l) is termed one-sided as it is only ..."
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Converter and Filter Circuits (Newnes Circuits Series)
Rudolf Graf

Excerpt - page 42: "... Rl + R21'z fa-27rC R3 X R1Rz When designing a filter of this type it is best to select a value for C1 and C2, keeping them equal. Typical audio filters have capacitor values from 0.01 to 0.1 AF, which will result in reasonable values for the resistors. ..."
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Spectral Analysis and Filter Theory in Applied Geophysics
Burkhard Buttkus

Excerpt - page 166: "... be determined by filtering the signal with a narrow bandpass filter and calculating the mean square of the filter output: PT(f,Of) = ~i ~ 2T 1 _TX2(t,f,Af)dt . (8.48) x(t, f, 0 f) describes that portion of ..."
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Estimation and Prediction of Ballistic Missile Trajectories (Rand Report No. MR-737-AF)
Jeffrey Isaacson

The Photographer's Guide to Filters (Photographers Guide)
Lee Frost

Active Filter Cookbook, Second Edition
DON LANCASTER

The Circuits and Filters Handbook, Second Edition
Wai-Kai Chen

High Frequency Continuous Time Filters in Digital CMOS
Shanthi Pavan and Yannis Tsividis

Water Treatment Principles and Design
James M. Montgomery

Excerpt - page 170: "... size distributions of both the raw water particles and the filter aid, filtration rate, and desired filtration efficiency. When head loss ..."
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Medical Instrumentation: Application and Design
John G. Webster

Excerpt - page 349: "... m/s The do component must be removed with a high-pass filter in the AF amplifier. We require a corner frequency of about 100 Hz ..."
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Turbulent Flows
Stephen B. Pope

Excerpt - page 580: "... ~ 6.90 (13.78) t-; ti and that for the Gaussian filter it is af = 122/3r( 3 ~ i 7.10. 13.15 Consider (13.79) E(x) ..."
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Radar Signal Processing (McGraw-Hill Electronic Engineering)
Mark Richards

Excerpt - page 169: "... time and in response to Doppler mismatches. The ambiguity function (AF) is an analytical tool for waveform design and analysis that succinctly characterizes the behavior of a waveform paired with its matched filter. The AF is useful for examining resolu- tion, side lobe ..."
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Principles of Network and System Administration
Mark Burgess

Excerpt - page 380: "... their own printjobs: # /etc/printcap (lprng) myprinterllp :if=/local/bin/lpf # LF/CR filter :af=/var/spool/lpd/acctfil :lf=/var/spool/lpd/printlog :sd=/var/spool/myprinter :lp=xxx.yyy.zzz.mmm%9100 :rw :sh The IP address of the ..."
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Fibre Optic Communication Devices
Norbert Grote and Herbert Venghaus

Excerpt - page 359: "... optical signal (correlator) At filter Icomp. ft) output fO+AC optical filter Afb--a fO+Af fO+Af optical clock - time wavelength:X2 -o- electrical optical Fig. ..."
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Unlimited Power: A Black Choice
Anthony Robbins and Joseph McClendon Iii

Excerpt - page 345: "... we do or do not do in our lives. These filters affect anchoring and everything else we've discussed in this book. ..."
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Spacecraft Sensors
Mohamed M Abid

Excerpt - page 69: "... The signal in Figure 2.15 is filtered by a band-pass filter of band- width Of, and ... a function of the frequency. s(t,f,Af) s2t,f,Af Averaging Y~s(f,~f Gs(f) s(t) Modulator Band-pass filter: Af circuit ..."
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Renewable Energy: Sources For Fuels And Electricity
Thomas B. Johansson, Henry Kelly, Amula K. N. Reddy, and Robert H. Williams

Excerpt - page 823: "... are the contact process (see figure 2a, [4]), the anaerobic filter(AF), operated in upflow (see figure 2b, [51) and downflow versions ..."
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Schaum's Outline of Electronic Devices and Circuits, Second Edition
Jimmie J. Cathey

Excerpt - page 68: "... sin cotj V; (b) VLO = 2Vr 2.51 A shunt filter capacitor (see Example 2.13) is added to the full-wave rectifier of Problem 2.50. Show that the ripple factor is given by F, = 2/(4fRLC - 1) ti 1/2fRLC. 2.52 Add a 470 AF filter capacitor across points a, b in the full-wave rectifier ..."
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Modern Digital and Analog Communication Systems (The Oxford Series in Electrical and Computer Engineering)
B. P. Lathi

Excerpt - page 149: "... output g2(t) is applied to a unity gain ideal low-pass filter of bandwidth A f Hz (Fig. P3.7-6). Show that if A f is very small (Af --+ 0), the filter output is a dc signal of ..."
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Linux System Administration, Second Edition (Craig Hunt Linux Library)
Vicki Stanfield and Roderick W. Smith

Excerpt - page 322: "... 322 Chapter 10 Printers and the Spooling Subsystem :if=/var/spool/lpd/epson/filter: :af=/var/spool/lpd/epson/acct: :lp=/dev/null: This pri ntcap file example contains the configuration for ..."
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Mastering Red Hat Linux 9
Michael Jang

Excerpt - page 727: "... effect of a new line. of Associated with an accounting filter (af). i f Uses an input filter (i f) for a ..."
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Fluorescence Spectroscopy in Biology: Advanced Methods and their Applications to Membranes, Proteins, DNA, and Cells (Springer Series on Fluorescence)
Martin Hof, Rudolf Hutterer, and Vlastimil Fidler

Excerpt - page 112: "... .*0* 001111111111111111 Excitation/ High NA Objective PiFoc Polarization =NEW Filter AF Z Dichroic Mirror CA PF ... / DS Dichroic Mirror Emission/Polarization Filter (EF/PF) Confocal Aperture (CA) 0U d 635nm Excitation/ Polarization Filter ..."
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Teach Yourself Electricity and Electronics, Fourth Edition (Teach Yourself)
Stan Gibilisco

Excerpt - page 433: "... not, and should not, be much greater. An audio notch filter is a band-rejection filter with ... 3000 Hz. Some sophisti- cated AF notch filters can tune themselves automatically. When an interfering carrier ..."
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An Introduction to Digital and Analog Communications
Simon Haykin and Michael Moher

Excerpt - page 77: "... Equation (2.138) states that the energy spectral density of the filter input at sonic frequency f equals the energy of the filter output divided by 2Af, where Af is the filter bandwidth centered on f. We may therefore ..."
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3D Studio MAX® R3 Bible
Kelly L. Murdock

Excerpt - page 466: "... Shellac 40 ~ _ p x p/Bottom AP NONE AF Adobe Photoshop Plug- In Filter AF Adobe Premiere Video Filter tmap ff Bricks AV ..."
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How to Test Almost Anything Electronic
Delton T. Horn

Excerpt - page 50: "... V -~ V+ - + 270 V Vi " To filter 150 AF D2 + (series) 135 V T C2 1 D1 (shunt) ..."
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UWB Communication Systems: A Comprehensive Overview (Eurasip Signal Processing and Communications)
Thomas Kaiser, Andreas F. Molisch, Ian Oppermann, and Maria Gabriella Di Benedett

Excerpt - Front Matter: "... important consequences for the design of optimum receiver structures (matched filters). Af- ter those fundamental investigations, Section 2.4 to Section 2.6 describe ..."
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Electronics: Circuit And Analysis
Dinesh C. Dube

Excerpt - page 339: "... APPLICATIONS 339 And the gain magnitude equation for the second-order filter is, AF V. [J{1+(f/fH)2}] vi Where, AF = (1 + RF/R1) is ..."
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Linux Samba Server Administration (Craig Hunt Linux Library)
Roderick W. Smith

Excerpt - page 221: "... Printing to an SMB/CIFS Shared Printer optra-e: :sd=/var/spool/lpd/optra-e: :mx#0: :sh: :if=/var/spool/lpd/optra-e/filter: :af=/var/spool/lpd/optra-e/acct: :lp=/dev/null: This queue includes several normal-looking options, including the sd, ..."
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Mathematical Physics: Applied Mathematics for Scientists and Engineers
Bruce R Kusse and Erik A. Westwig

Excerpt - page 293: "... If we pass the sampled signal through an ideal low-pass filter with wa, the output of the filter will have a Fourier transform Af(w) that is exactly equal to A(w), and consequently the signal ..."
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Building Scientific Apparatus
John H. Moore, Christopher C. Davis, Michael A. Coplan, and Sandra C. Greer

Excerpt - page 523: "... to zero as well. Common bandwidth-narrowing circuits are the resonant filter and low-pass filter. For resonant ... the filter is tuned and Af is the bandwidth. Practical values of Q for electronic resonant ..."
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Broadband Packet Switching Technologies: A Practical Guide to ATM Switches and IP Routers
H. Jonathan Chao, Cheuk H. Lam, and Eiji Oki

Excerpt - page 22: "... shared high-speed medium via an interface consisting of an address filter (AF) and an output FIFO buffer. The AF examines the header ..."
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Handbook of Industrial and Hazardous Wastes Treatment, Second Edition
Lawrence K. Wang, Yung-Tse Hung, Howard H. Lo, and Constantine Yapijakis

Excerpt - page 497: "... anaerobic sludge blanket (UASB), (b) anaerobic contact (AC'), (c) anaerobic filter (AF), (d) hybrid UASB with filter (UASB/AF), (e) expanded granular sludge ..."
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Acoustic Signal Processing for Telecommunication (The International Series in Engineering and Computer Science)
Steven L. Gay and Jacob Benesty

Excerpt - page 49: "... at the reduced rate Ft/D. In each subband, an adaptive filter (AF) with input xi (m) is used to cancel the echo ..."
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Biological Wastewater Treatment (Environmental Science & Pollution) (Environmental Science and Pollution Control Series, 19)
C. Leslie Grady

Excerpt - page 13: "... Packed bed Submerged packed tower with X small media Anaerobic filter AF Submerged packed tower with X large media 'Nitrification. bPhosphorus uptake ..."
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