Description
The Radio Data System (RDS) broadcasts small digital data over Frequency Modulation (FM) radios. The main purpose of RDS is to broadcast information such as the name of a song, artist, and radio station. The thesis presented here is an attempt to explore the potential of RDS by developing an ad hoc broadcast scheme. The design of the broadcast scheme consists of the following characteristics: a cyclic redundancy check (CRC) error detection for more reliable data broadcasts, the ability to support multiple transmitters and receivers, and a fragmentation disassemble and reassemble process to accommodate larger size data broadcasts. Traditionally, RDS is broadcasted over a metropolitan-scale distances by radio stations on a dedicated FM frequency. In this thesis, the broadcast scheme is designed to use an unlicensed FM frequency to broadcast data over a maximum distance of 200 feet. This is in accordance to the Federal Communication Commission (FCC) regulations for unlicensed FM broadcasting. To test the ad hoc broadcast scheme, we configured commercial FM transceivers and antennas, as well as custom built antennas. Real time performance measurements were conducted between a single transmitter and a single receiver. Measurements were based on short and long broadcasts ranging from 10 to 200 feet. Throughputs were determined for the short and long broadcasts and were observed to have a 52-53% error than the ideal RDS throughput rate. Additionally, the goodput was found to have a 68-69% percent error than the ideal RDS goodput rate for the short and long broadcasts. Overall, the real time performance measurements showed information on the behavior of the transmitter and receiver's hardware. In addition, testing with a single transmitter and a single receiver provided a baseline of the performance of the broadcast scheme. It is hoped that the information presented in this thesis will act as a starting point for future tests involving multiple transmitters and receivers using the unlicensed FM for short-distance digital communication.
