DocumentCode :
1475748
Title :
Nonintrusive measurements of the telephone channel
Author :
Gänsler, Tomas ; Salomonsson, Göran
Author_Institution :
Dept. of Appl. Electron., Lund Univ., Sweden
Volume :
47
Issue :
1
fYear :
1999
fDate :
1/1/1999 12:00:00 AM
Firstpage :
158
Lastpage :
167
Abstract :
Algorithms for a system which performs in-service nonintrusive measurements of telephone line parameters such as echo path delay, echo attenuation, speech and noise levels are presented. It forms the theoretical background of a hardware implementation of the ITU-T P.561 recommendations for nonintrusive assessment of quality of a telephone network for voice transmissions. The type of input signal to the echo path, whether it is speech, fax, or data, has to be determined during the measurement procedure. In the system, the relevant parameters are estimated by means of frequency-domain block-processing algorithms and the estimation process is controlled by algorithms monitoring the signal flow. The complexity of the echo path estimation algorithm is determined and compared to a standard procedure based on the adaptive normalized least mean square (NMLS) algorithm. Simulations showing the performance of the system in single-and double-talk situations are presented. Examples of results from the hardware real-time implementation operating on an international connection are also shown
Keywords :
attenuation measurement; frequency-domain analysis; parameter estimation; signal processing equipment; telecommunication equipment testing; telephone lines; telephone networks; voice communication; ITU-T P.561 recommendations; NMLS algorithm; adaptive normalized least mean square; data; double-talk; echo attenuation; echo path delay; echo path estimation algorithm; estimation process; fax; frequency-domain block-processing algorithms; hardware implementation; in-service nonintrusive measurements; input signal; international connection; noise level; signal flow monitoring; simulations; single-talk; speech level; telephone channel; telephone line parameters; telephone network; voice transmissions; Attenuation measurement; Delay; Frequency estimation; Hardware; Noise level; Noise measurement; Parameter estimation; Performance evaluation; Speech enhancement; Telephony;
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/26.747823
Filename :
747823
Link To Document :
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