DATA COMMUNICATION PRINCIPLES Frequency Shift Keying FSK Frequency

DATA COMMUNICATION PRINCIPLES : Frequency Shift Keying (FSK)

Frequency Shift Keying (FSK) In binary FSK, two signals with different carrier frequencies are used to represent binary data. Since these carriers have different frequencies, they can easily be distinguished at the receiver. It has the added benefit over the ASK that if a bit is lost during transmission, it is known that the bit is lost, since there should always be a carrier signal for zero or one. The baud rate in this case is again equal to the bit rate. As compared to ASK, signal synchronization is easier to maintain in FSK. In ASK, it is possible for the receiver to lose sync with the transmitter when a long string of no-carrier signals occurs. In FSK, the difference between the carrier frequencies is kept large enough so that energy is not trapped in their byproducts. If M carriers are used for FSK with M > 2, then we have the M’ary FSK with the baud rate equal to of the bit rate, The binary FSK shown in Figure 3 - 15 modulates a positive baseband pulse with a low frequency carrier and a negative baseband pulse with a high frequency carrier signal.

REFERENCES • Ahmad A. - Data Communication Principles. For Fixed and Wireless Networks • Cornelius T. Leondes - Database and Data Communication Network Systems, Three-Volume Set_. . -Academic Press