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• The application of adaptive filters to active sound control

Publication Year: 1989, Page(s):8/1 - 8/4
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Active sound control involves the introduction of a number of secondary acoustic sources whose outputs are arranged so as to destructively interfere with the sound from some primary' source. The technique works best with low frequency periodic signals where the wavelength is long and the waveform predictable. The method used is to adapt the output from a number of loudspeakers so as to minimise t... View full abstract»

• IEE Colloquium on Adaptive Filters' (Digest No.46)

Publication Year: 1989
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The following topics were dealt with: RLS algorithm as channel estimator; LMS for chirped signal tracking; fast algorithms for least squares linear prediction; digital data receivers adaptive adjustment using predetection filtering; time domain equalisers for digital microwave systems; adaptive filter algorithms; adaptive periodic noise cancellation for acoustic howling control; active sound contr... View full abstract»

• Fast algorithms for least squares linear prediction based on orthogonal rotations

Publication Year: 1989, Page(s):3/1 - 3/5
Cited by:  Papers (9)
| | PDF (152 KB)

Cioffi (see Proc. International Conf. on ASSP, vol.503, p.1584, 1988) presented a fast Kalman algorithm that is based on the QR-decomposition (QRD) technique. The key to Cioffi's algorithm is a connection between the solution to the linear prediction problem and the solution to an auxiliary problem (the so-called backward prediction problem). This is the same as the standard fast Kalman approach e... View full abstract»

• Adaptive periodic noise cancellation for the control of acoustic howling

Publication Year: 1989, Page(s):7/1 - 7/4
Cited by:  Papers (4)
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Presents a new method of containing the effects of acoustic echoes. The method is based on an adaptive periodic noise canceller (APNC), itself a variation on the well-known adaptive line enhancer. A simple but effective solution to the problem of containing howling in public address and handset free telephone systems has been proposed in the form of an APNC based on a FIR filter and driven by the ... View full abstract»

• Self-tuning active noise control

Publication Year: 1989, Page(s):9/1 - 9/4
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Presents the design and implementation of a self-tuning active noise control (ANC) system suitable for reduction of unwanted noise emanating from a compact source in a three-dimensional non-dispersive (linear) propagation medium. The concept of self-tuning control has been utilised by properly integrating the processes of identification and control so that it suits the application. Moreover, as re... View full abstract»

Publication Year: 1989, Page(s):4/1 - 4/4
| | PDF (156 KB)

Describes methods used for the adjustment of a decision feedback equalizer in a digital data transmission system. The equalizer minimizes noise in the equalized signal subject to exact equalization of the channel. The equalizer employs an adaptive linear feedforward filter at its input which replaces the roots of the Z-transform of the channel that lie outside the unit circle by the complex conjug... View full abstract»

• A performance study of the RLS algorithm as a channel estimator in a nonstationary environment

Publication Year: 1989, Page(s):1/1 - 110
Cited by:  Papers (2)
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The performance of an exponentially windowed RLS algorithm carrying out system identification of a nonstationary environment is considered. The two criteria used for assessing the performance of the algorithm are the steady state mean-squared error (MSE) and the initial rate of convergence. The effect of both filter order and level of nonstationarity is illustrated, with the LMS adaptive algorithm... View full abstract»

• Digital implementation of time domain equalizers for digital microwave systems

Publication Year: 1989, Page(s):5/1 - 5/4
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Line-of-sight microwave links are currently used to transmit high speed data in the telecommunication network. The trend in modulation formats is typically towards multilevel quadrature amplitude modulation (OAM) with symbol rates in the range 20-75 Mbaud and carrier frequencies in the region of 2-20 GHz. For systems operating at the lower carrier frequencies long hops are feasible, requiring adap... View full abstract»

• Superiority of LMS over RLS for tracking a chirped signal

Publication Year: 1989, Page(s):2/1 - 2/6
Cited by:  Papers (1)
| | PDF (200 KB)

When an adaptive filter, receiving coloured inputs, has to track a nonstationary environment, it is often said that the RLS algorithm will outperform the LMS one because it is known to converge faster. However, convergence speed is a transient property, independent of the amount of noise, while tracking is a steady-state performance and is therefore also influenced by the noise level. The answer i... View full abstract»

• Real time implementation of adaptive filter algorithms for high-speed data transmission

Publication Year: 1989, Page(s):6/1 - 6/3
Cited by:  Patents (1)
| | PDF (152 KB)

A method of reducing the overall number of operations performed by a near maximum likelihood detector by placing a filter (known as the pre-filter) ahead of it is described. The tap weights of the pre-filter are adjusted adaptively such that when it is cascaded with the channel, their combined sampled impulse response will be minimum phase. An algorithm developed at Loughborough University is used... View full abstract»