ACRO.IT Acronym Directory

Operation of QAM is somewhat simple; it operates by modulating a carrier sine wave signal in amplitude and phase. In QAM coding scheme each symbol is specific combination of signal amplitude and phase. The effects of modulation were that the resulting signal was not the single frequency, but rather the range of frequencies. The range of frequencies were related to the signal which is modulated to the some given carrier frequency. The BW of QAM signal is equivalent to the symbol rate (2400 symbols/sec ó 2400Hz). Simply 3200 symbols per second require about 3.2KHz of bandwidth. It later became obvious that telephone network offers more bandwidth. The highest rate [standard V.34] uses the QAM modulation carrier of 1959Hz, and symbol rate of 3429 symbols/sec. V.34 requires 3430Hz of bandwidth (244 - 3674) Hz.