Features a unique program to estimate the power spectral density. The spectrum containing all significant details is calculated from a time series model. Model type as well as model order are determined automatically from the data, using statistical criteria. Robust estimation algorithms and order selection criteria are used to obtain reliable results. Unlike in FFT analysis, where the experimenter has to set the amount of smoothing of the raw FFT, the right level of detail is assessed using the data only.
在現代通信系統中，電話語音的頻帶被限制在300 Hz～4 kHz的范圍內，帶來了語音可懂度和自然度的降低。為了在不增加額外成本的前提下提高語音的可懂度和自然度，進行了電話語音頻帶擴展的研究。提出了一種改進的基于碼本映射的語音帶寬擴展算法：在碼本映射的過程中，使用加權系數來得到映射碼本。客觀測試結果表明，用此算法得到的寬帶語音的譜失真度比用一般的碼本映射降低至少2%。主觀測試結果表明，用此算法得到的寬帶語音具有更好的可懂度和自然度。
Abstract:
In modern communication systems， the bandwidth of telephone speech is limited from 300Hz to 4 kHz， which reduces the intelligibility and naturalness of speech. Telephone speech bandwidth extension is researched to get wideband speech and to improve its intelligibility and naturalness， without increasing extra costs. This paper put forward an improved algorithm of speech bandwidth extension based on codebook mapping. In the process of codebook mapping， weighted coefficients were used to get mapping codebook. Objective tests show that spectral distortion of wideband speech obtained by this algorithm reduces at least 2%， comparing to conditional codebook mapping. Subjective tests show that the wideband speech obtained by this algorithm has better intelligibility and naturalness.
ACPR (adjacent channel power ratio), AltCPR (alternatechannel power ratio), and noise are important performancemetrics for digital communication systems thatuse, for example, WCDMA (wideband code division multipleaccess) modulation. ACPR and AltCPR are bothmeasures of spectral regrowth. The power in the WCDMAcarrier is measured using a 5MHz measurement bandwidth;see Figure 1. In the case of ACPR, the total powerin a 3.84MHz bandwidth centered at 5MHz (the carrierspacing) away from the center of the outermost carrier ismeasured and compared to the carrier power. The resultis expressed in dBc. For AltCPR, the procedure is thesame, except we center the measurement 10MHz awayfrom the center of the outermost carrier.
This toolbox contains Matlab code for several graph and mesh partitioning methods, including geometric, spectral, geometric spectral, and coordinate bisection. It also has routines to generate recursive multiway partitions, vertex separators, and nested dissection orderings and it has some sample meshes and mesh generators.
The toolbox contains a Matlab interface to Leland and Hendrickson s Chaco partitioning package, but it doesn t contain Chaco itself. The file "chaco/README" tells how to install the interface to Chaco. It also contains a Matlab interface to Karypis et al. s Metis partitioning package, using Robert Bridson s "metismex" code.
Routine mar1psd: To compute the power spectum by AR-model parameters.
Input parameters:
ip : AR model order (integer)
ep : White noise variance of model input (real)
ts : Sample interval in seconds (real)
a : Complex array of AR parameters a(0) to a(ip)
Output parameters:
psdr : Real array of power spectral density values
psdi : Real work array
in chapter 12
一個非常好的時間序列工具箱，詳細使用說明見P. M. T. Broersen, Automatic spectral Analysis with Time Series Models, IEEE Transactions on Instrumentation and Measurement, Vol. 51, No. 2, April 2002, pp. 211-216.
Mobile phones are constantly decreasing in size, thereby complicating the acoustical
functionality. Signal processing methods can be used to partially mitigate
this problem. In this paper we suggest a method which uses multiple spectral
subtraction functions and two microphones, introducing only a short signal delay.
