Chapter 2: Background The history of radio broadcasting is short, but rich. Over the last century, radio broadcasting techniques have been constantly shifting, with a variety of methods introduced, implemented, and revised as necessary to maintain reliable transmission quality for a broadcast coverage area. This chapter provides an overview of some of these methods, their strengths and weaknesses, and emerging trends in radio broadcasting. 2.1 History of Radio Technology The first step in radio technology came from James Clerk Maxwell who showed mathematically in 1873 that electromagnetic waves could propagate in the air, and Heinrich Hertz first confirmed this theory in 1888. In 1894 Guglielmo Marconi was credited as the first to successfully build a wireless telegraphy system, although the patents were debated by Nikola Tesla who claimed that they were identical to his patents. Marconi did however make the first transatlantic experimental radio transmission in 1901. At this point, all communications were using “spark gap” technology, which meant that a single broadcast covered the entire spectrum. In 1906 the first Amplitude Modulation (AM) radio was invented by Reginald Fessenden allowing more than one station to broadcast in an area. The first radio broadcast as we recognize it, complete with a human voice and music, occurred in San Jose in 1909. This radio station, called “San Jose Calling” was using spark gap technology, however daily radio broadcasting didn’t begin to occur until 1916 when Harold Power began to broadcast out of Tufts University. At this point receivers were built as crystal sets, however by the mid-1920s vacuum tube radios revolutionized receivers and transmitters allowing for much higher amplification of the signal. The invention of frequency modulation (FM) as well as single sideband (SSB) were invented by amateur radio operators during the 1930s and were established as commercial modes
4.1 Results The project aimed to solve the issues presented to the IQP team by WICN. The proposed solutions at the beginning of the project included expansion of the radio broadcast signal, opening of a new booster station, purchasing of an existing radio tower or the development a prototype internet booster station. After researching each of these potential solutions, the team focused on the development of the prototype internet booster station. The team divided the development of the internet booster station into two main parts to the prototype: the hardware and software. The hardware consisted of the AM modulation and RF modulator and transmitter. The software was an android app that would obtain WICN online station, synchronize the clock through GPS, and output the audio at precise times based on the distance between the two booster stations. When developing the prototype the team was able to successfully obtain the GPS location and stream WICN’s online station. The prototype would output the stream to audio jack to the AM transmitter. The AM transmitter was then able transmit the signal to an AM radio receiver on the other side of the room. Unfortunately the team was unable to properly synchronize the clocks down to a microsecond due to the precision of the on board GPS. 4.2 Errors As the project moved forward the team encountered several problems that prevented the team from truly finish building either of the possible solutions. The team ran into issues with both the hardware and with the software. For the hardware, there were some problems with the circuit including that the team had to design an AM modulation circuit, not a FM modulation because of the difficulty the team