SCA system (Subsidiary Communications Authorization) Implementation of Text Transmission on Broadcasting System

Abstract

FM Radio broadcasting systems almost entirely have used the stereo system. A transmitter and receiver FM able to process the information signal with the frequency more than 75 kHz so that stereo system can be realized easily. Stereo broadcast bandwidth requirement is equal to 53 kHz, the rest bandwidth is applicable to be other that is by adding SCA system (Subsidiary Communications Authorization). SCA used to deliver and accept the text data. Bandwidth of SCA system requires being limited in order not to bother the main broadcast program. Band from the limited SCA system used to deliver the digital information, for the reason need a digital modulation to optimize the bandwidth. Speed of data also require to be paid attention because the limited bandwidth. Data delivered have the start code so that only just certain receiver able to accept the data. Information delivery of SCA system is by using frequency modulation with the 67 kHz carrier frequency. To limit the bandwidth hence require to be filtered before transmitted. Digital information beforehand converted to in the form of analogue with the digital modulation FSK. Baud rate of delivery and data acceptance is same that is equal to 600 bps. Data delivered use the start code in the form of certain character which not present at the computer keyboard. Data Acceptance method represent the process which have reverse from delivery process. System have earned realized that is data sent acceptable successful and not bother the main broadcast program. By adding this system, modulation signal from stereo signal have to be decrease 11,11 %. Keyword: SCA, asynchronous serial, FSK, FM, Broadcasting system