Voice encryption system for FM transceiver applications

• Main Authors: Co, Joselito T., Gervacio, Giancarlo A., Mallari, Vincent P., Quisumbing, Christian G.
• Format: text
• Language: English
• Published: Animo Repository 1995
• Subjects: Voice; Speech scramblers; Data transmission systems; Digital modulation; Radio > Transmitter-receivers; Radio frequency modulation
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8641
• Institution: De La Salle University

The objective of this project study is to design and construct an electronic device which will be referred to as a voice scrambler for use in two-way radio communication.The scrambler or voice coder, as one may call it, converts the analog signal of the human voice into digital form. The original analog voice signal sent through a conventional microphone is converted into a digital format to take advantage of the relative ease in dealing with transmission and processing of digital signals. The circuit responsible for the said processing utilizes pulse code modulation with analog-to-digital and digital-to-analog conversion.The scrambler enables operators of frequency modulated (FM) transceivers to code or encrypt audio transmissions made over the airwaves. These coded modulations will be unintelligible to other radio operators without the proper decryption system. Only stations with the same type of encryption method used will be able to decipher transmissions over the air.Due to the vast number of radio users in the VHF band, some difficulties arise when a group or even an individual wants to keep transmissions as confidential as possible. The scrambled signal will be the basis on which private conversations may be made on air , with no threat to would-be listeners, human interference, or unwanted modulators.