Design of an Active Noise Control System Using Combinations of DSP and FPGAs

We use cookies to personalise content and ads, to provide social media features and to analyse traffic. We share info about use of our site with social media, ads and analytics partners. By continuing to browse you are agreeing to use of cookies. See details or close this message.

Page

100%

Specifications	Design of an Active Noise Control System Using Combinations of DSP and FPGAs
Business section

April 1996 6-21 © 1996 Actel Corporation Paper published in the 1995 PLD Conference Proceedings 6 Design of an Active No

Specifications	Design of an Active Noise Control System Using Combinations of DSP and FPGAs
Suggested Link Details/Purchase
Content	April 1996 6-21 © 1996 Actel Corporation Paper published in the 1995 PLD Conference Proceedings 6 Design of an Active Noise Control System Using Combinations of DSP and FPGAs Reza Hashemian, Senior Member IEEE Associate Professor, Northern Illinois University Field Programmable Gate Arrays (FPGAs) offer a quick and cost effective implementation for medium to large size digital designs that traditionally have been carried out mainly by ASIC and DSP implementation. However, there are still a number of processing-intensive applications that no single FPGA chip, developed today, can handle the entire design. In this paper, an experimental design of an active noise control system is introduced that combines both DSP and FPGA in a task oriented structure. In this design, data received by the local microphone and the output signals to the secondary speakers in the noise field are handled by the FPGA. This include I/O buffers, data paths, memory access, FIFO, bit-wise manipulations (data shift and logical operations), and the control block (FSM). Data crunching such as high speed manipulations and additions for updating the coefficients in the Signal Processing Block is handled by the DSP. There are two major design criteria considered here: 1) split the task between the FPGA and the DSP in order to reduce the number of DSP instructions as much as possible, and 2) make the devices to work simultaneously and with minimum dependency. Introduction As an alternative to passive noise cancellation techniques and often in combination with them, active noise cancellation (ANC) offers an effective solution in certain applications. Although still in the development stage, ANC is receiving considerable attention for applications involving industrial apparatus, dynamic systems, and domestic appliances. In contrast to passive techniques, ANC systems are small, portable, adjustable to different environments, and less costly. An ANC system can be effective across the entire noise spectrum, but it is particularly appropriate at low frequencies of up to 300 Hz, where passive systems are less effective. The success of an ANC system depends mainly on fulfilling two criteria: first, the anti-noise waveform must closely match the shape and frequency of the noise waveform; and second, the anti-noise wave must be precisely 180 degrees out of phase with respect to the original noise waveform, when reached to the target area. Failure to fulfill one or both of these criteria may cause the ANC system to generate a second acoustic noise rather than cancel the original one. These criteria apparently impose some restrictions on the canceling system and somewhat limit its application. First, for a highly effective canceling system the noise source must be nearly stationary in relation to the speaker emitting the anti-noise waveform. Second, the noise source should be located in close proximity to the ANC system and, for the best results, the target noise must be dominantly propagating in one direction. This suggests more of an effective “zone silencing” rather than an open area cancellation. Acoustic delay is another important issue that must be dealt with in a noise canceling system. Physically there are always distances between the source, the anti-noise generator (speaker) and the residue noise detector (microphone). These physical distances provide noise propagation delays which in turn cause different phase shifts, depending on the relative location of objects. In a general case of a non-periodic noise, prediction techniques and adaptive systems are used to deal with the problem. In this case, an ANC system is dependent on its ability to predict noise from its memory of the past, or adapt the response to the incoming signal as closely as possible. In a periodic noise system, however, prediction is simply done by storing one or more cycles of noise. This makes the periodic noise cancelers much simpler and more effective. And, as a matter of fact, periodic noise is one of the most common and dominated source of noise in industrial and even domestic environment today. Traditionally, two basic methods are used in ANC systems. In the first method, known as adaptive cancellation, noise is detected by one or more microphones. The system then adapts itself to generate anti-noise waveform which minimizes the residue (mic.) noise. Adaptive cancellation can be used for both periodic and non-periodic noise. However, when used with non-periodic noise the adaptive method is limited because it usually involves a prediction or an estimation process. Feed forwarding is often used to predict the noise before it reaches the target. As for the periodic noise, the adaptation and estimation is basically reduced to utilizing the past noise cycle for the generation of the present anti-noise waveform. The second type of active noise cancellation system is based on the synthesis method. This involves sampling and storing one or more noise cycles and, based on this information Customer-Authored Application Note AC104
Navigation	Previous Page / Next Page
Suggested Link Details/Purchase

Following Datasheets	nov_radiationdate-e_4 (1 pages) NPA_SKY67002_396LF_SKY67003_396LF_SKY67102_396LF (1 pages) NPH-20_1 (8 pages) NPH-21_1 (8 pages) NPH-24_1 (8 pages) NPH-25_1 (8 pages) NPH-26_1 (8 pages) NPH-27_1 (8 pages) NPH-28_1 (8 pages) NPH-38_1 (8 pages)
Check in e-portals	World-H-News Products Extensions Partners Automation Jet Parts
Sitemap Folder	group1 group2 group3 group4 group5 group6 group7 group8 group9 group10 group11 group12 group13 group14 group15 group16 group17 group18 group19 group20 group21 group22 group23 group24 group25 group26 group27 group28 group29 group30 group31 group32 group33 group34 group35 group36 group37 group38 group39 group40 group41 group42 group43 group44 group45 group46 group47 group48 group49 group50 group51 group52 group53 group54 group55 group56 group57 group58 group59 group60 group61 group62 group63 group64 group65 group66 group67 group68 group69 group70 group71 group72 group73 group74 group75 group76 group77 group78 group79 group80 group81 group82 group83 group84 group85 group86 group87 group88 group89 group90 group91 group92 group93 group94 group95 group96 group97 group98 group99 group100 Prewious Folder Next Folder