Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Methods for Recovery of Missing Speech Packets
Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
2011 (Engelska)Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
Abstract [en]

In packetized voice communication, speech packets are sometimes lost due to data transmission problems, e.g., signal fading, or interfering users and noise. For the recovery of missing speech packets, different methods are proposed. This thesis analyzes some recovery methods, and four variants of a waveform substitution method used during the objective analysis. This method is based on slow varying speech parameter estimates. These parameters include the short time energy (STE) and the zero crossing (ZC) measure. This technique is implemented in two different ways based on the slow varying parameters. These parameters are stored in the previous packet. If a speech packet is lost, it is recovered by the information stored in the previous packets. Both implementations differ only in the use of the zero crossing information. The short time energy estimation is the same in both implementations. A slight modification is made in these two implementations where the estimated speech parameters are stored in the previous and in future packets in order to recover two consecutive packets. This modification is applied only if the speech signal is already saved at the transmitter because it requires the future packets to store the information of previous packets, i.e., a non-causal solution. However, a causal solution is obtained if the signal is allowed to be delayed by one packet. The speech quality of the reconstructed speech signal is analyzed and compared between the four implementations. The implementation of these methods has been validated by subjectively observing the recovered speech packets, and by considering the improvement of the objective measures mean opinion score (MOS), mean square error (MSE) and signal-to-noise ratio (SNR). The recovery of samples within the packets is also discussed. The recovery of samples within a packet is done by the Fast Fourier Transform (FFT) block code method. The FFT block code method is implemented by an iterative algorithm. This method is validated by subjective observations and improvements in objective measures mean square error (MSE) and signal to noise ratio (SNR). The VAD is also used for the waveform substitution method and in the introduction of channel noise. After subjective observations and objective measures, it is concluded that modified method A provides better performance for the recovery of speech packets and the FFT block code method has been validated for recovering the samples within a packet.

Abstract [sv]

Denna magisteravhandling beskriver två metoder för återskapande av förlorade talpaket, samt rekonstruktion av talsignal då ett fåtal signalsampel saknas. Därtill föreslår avhandlingen utökningar till dessa två metoder för att hantera två efterföljande saknade talpaket. Metoderna är presenterade och utvärderade på talsignaler där signalvärden har förstörts enligt en given kanalmodell.

Ort, förlag, år, upplaga, sidor
2011. , s. 93
Nyckelord [en]
Slow varying parameters, Short time energy (STE), Zero crossing (ZC) measure, Modified STE methods, FFT block code method, STZR, STZL, Consecutive speech packets.
Nationell ämneskategori
Signalbehandling Telekommunikation
Identifikatorer
URN: urn:nbn:se:bth-6024Lokalt ID: oai:bth.se:arkivex40EC7F884C012DB6C125793A004855EFOAI: oai:DiVA.org:bth-6024DiVA, id: diva2:833441
Uppsök
teknik
Handledare
Tillgänglig från: 2015-04-22 Skapad: 2011-10-31 Senast uppdaterad: 2015-06-30Bibliografiskt granskad

Open Access i DiVA

fulltext(1469 kB)186 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 1469 kBChecksumma SHA-512
eec2f03bd45918d226fdd8a3adc23c386ed4343ffd5ca92a6fb91a8613115ba9f9e456ce7bb6b2a5f0262e2f29a375e0fd96f359f792d9106bb2364bb0d2ab53
Typ fulltextMimetyp application/pdf

Av organisationen
Sektionen för ingenjörsvetenskap
SignalbehandlingTelekommunikation

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 186 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

urn-nbn

Altmetricpoäng

urn-nbn
Totalt: 257 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf