Speech privacy for modern mobile communication systems

Speech privacy techniques are used to scramble clear speech into an unintelligible signal in order to avoid eavesdropping. Some analog speech-privacy equipments (scramblers) have been replaced by digital encryption devices (comsec), which have higher degree of security but require complex implementations and large bandwidth for transmission. However, if speech privacy is wanted in a mobile phone using a modern commercial codec, such as the AMR (Adaptive Multirate) Codec, digital encryption may not be an option due to the fact that it requires internal hardware and software modifications. If encryption is applied before the codec, poor voice quality may result, for the vocoder would handle digitally encrypted signal resembling noise. On the other hand, analog scramblers may be placed before the voice encoder without causing much penalty to its performance. Analog scramblers are intended in applications where the degree of security is not too critical and hardware modifications are pr...

• Type: Conference
• Year: 2008
• Where: ICASSP
• Authors: Jose Francisco de Andrade, Marcello Luiz Rodrigues de Campos, Jose Antonio Apolinario
• Keywords: Analog Scramblers, Digital Encryption, ICASSP 2008, Signal Processing, Speech Privacy