staggered quadrature phase-shift keying

In SQPSK, the data is placed alternately on two channels or streams called the I channel (for "in phase") and the Q channel ("phase quadrature"). A single phase transition can never exceed 90 degrees. This property contrasts SQPSK with conventional quadrature phase-shift keying (QPSK), in which the phase can sometimes change by 180 degrees (two 90-degree shifts in a single transition). The average magnitude of the phase transitions is smaller with SQPSK than with conventional QPSK. The result of the smaller average phase "jump" is an improved signal-to-noise ratio (SNR) and a reduced error rate.

SQPSK and QPSK are not the only methods of PSK in common use. In binary phase-shift keying (BPSK) there are two possible states for the signal phase: 0 and 180 degrees. In QPSK and SQPSK there are four possible states: 0, +90, -90 and 180 degrees. In multiple phase-shift keying (MPSK) there can be more than four possible states for the signal phase. An example is the use of eight phase states: 0, +45, -45, +90, -90, +135, -135 and 180 degrees. More than eight phase states are rarely used because that takes the signal complexity past the point of diminishing returns and the error rate actually increases.

Read more about staggered quadrature phase-shift keying: - TDRSS Telecommunication Services compares three methods of PSK. - Crosslink describes digital modulation methods including PSK. - Phil Karn describes the implementation of SQPSK in amateur radio digital communications.

Do you have something to add to this definition? Let us know. Send your comments to techterms@whatis.com

Digg This!     StumbleUpon     Del.icio.us

RELATED CONTENT Network management frameworks: FCAPS and ITIL Network management is a complex topic. Thus far, two frameworks exist that can be of some use for understanding and taming network management: FCAPS... What is a logical network? How do you improve one? Learn what logical and physical networks are and how to improve them, in this expert response with networking fundamentals expert, Chris Partsenidis. Interop Las Vegas 2008: Special news coverage SearchNetworking.com editors were in Las Vegas to bring you the most detailed coverage of Interop Las Vegas 2008.

RELATED GLOSSARY TERMS Terms from Whatis.com − the technology online dictionary AMTOR  (SearchNetworking.com) availability  (SearchNetworking.com) 1) In a telephone circuit, availability is the ratio between the time during which the circuit is operational and elapsed time. 2) In a network...