Pulse Code Modulation

Modulation Standards for convergence

There are many different types of Modulation standards that can be used for convergence. The ones that I will be discussing will be Amplitude-Shift Keying (ASK), Frequency-Shift Keying (FSK), Phase-Shift Keying (PSK), and Quadrature Amplitude Modulation (QAM).

The first modulation standard I will discuss will be Amplitude-Shift keying. ASK is any digital modulation scheme that uses a finite number of signals to symbolize the digital data. Every amplitude has its own pattern of binary digits. (Wikipedia, ASK) Each of the amplitudes has an equal number of bits, each pattern of bits forms a symbol represented by the amplitude. ASK is sensitive to atmospheric noise and distortions on different routes. (Wikipedia, ASK) ASK is generally used to transmit digital data over optical fiber.

The next modulation standard is Frequency-Shift Kyeing (FSK) which is a frequency modulation scheme which information is sent digitally through frequency changes of a carrier wave. (wikipedia, FSK) Binary Frequency-Shift keying (BFSK) uses two frequencies to transmit binary information, with BFSK the one is classed the mark frequency while the zero is called the space frequency. (wikipedia, FSK) Other forms of FSK are Minimum frequency-shift keying (MSK) and Audio frequency-shift keying (AFSK). In MSK the difference between higher and lower frequency is similar to half the bit rate, waveforms used to represent a zero and a one bit differ by exactly half a carrier period. AFSK is a modulation that digital data is symbolized by changes in frequency of an audio tone. Similar to BFSK a binary one represents a mark while a binary zero represents a space. (Ellis 1) AFSK differs from FSK because in preforming at baseband frequencies. AFSK is used for high speed data because it has the advantage that encoded signals that will pass through AC links. (wikipedia, FSK)

The next modulation standard is Phase-Shift keying; PSK is a digital scheme...