M.Sc. Tezi Görüntüleme
In order to prevent the unwanted eavesdropping to the communications over theanalog handheld two-way radios, a low cost, small voice encryption unit with easy
integration capability through the radio microphone and speaker jacks has been designed.Before the design phase, subjects like analog handheld two-way radio, two-way radio
communication, modulation types and cryptology have been studied. C programminglanguage and dspic microprocessor is used in the design. Hardware with embedded
software was used in the design approach.Before the audio signal is sent to the microphone input of the transmitting radio,
signals are digitized, encrypted and converted back in to the analog signal by the DigitalEncryption unit.
On the receiving end, the encrypted analog audio signal levels are adjusted throughan equalizer in order to attain the appropriate logic1 and logic0 signal levels. The
adjusted signals are digitized, decrypted and converted back in to the analog audio signalby the Digital Encryption unit.
The developed Digital Encryption unit has been tested in the laboratory environmentas well as with the PMR handheld two-way radios in the UHF band and successful results
has been achieved.
Key Words: Two Way Radio, Analog Two Way Radio, Two Way Radio Communication,
Half-Duplex, Push-to-Talk (PTT), Secure Communication, MSK, Crypto,Digital Crypto, Encryption, Audio Encryption.