Binary PSK
QPSK.
1. Two different phases are used to
represent two binary values.
1. Four different phases are used to represent two binary values.
2. Each signal element represents only one bit.
2. Each signal element represents
two bits
See the question "What is QPSK". If you want the difference between QPSK and some other modulation system, you'll need to name the other one.
the phase shift allowed in OQPSK is 900 whereas in QPSK it is 1800 . QPSK is used in uplink whereas OQPSK is used in downlink.
in psk,we use only single type of phase shift for a bit transition. in qpsk,we use 4 types of phase shifts for a bit transition.
BPSK=> 1.The BPSK stands for “Binary Phase-shift keying”. 2.DPSK is a not a method of BPSK, where there is no reference phase signal. 3.amplitude shift keying 4.lesser bandwidth more probability error DPSK=> 1.The DPSK stands for “Differential phase-shift keying”. 2.DPSK is a method of BPSK, where there is no reference phase signal. 3.It is one type of phase modulation used to transmit data by altering the carrier wave’s phase. 4.greater bandwidth probability error less
In abs. PSK only instant phase for the incoming bits are considered. For DPSK, the difference between previous phase and the present phase is considered. Example: If BPSK is used, then for 0 if phase if pi and for 1 it is 0, then for abs. BPSK the phase states for the bit stream 1010 will be 0,pi,0,pi for DPSK, we assume initial phase is zero and a rule that , if incoming bit is zero, then phase difference is 0 and if it is 1 then, phase difference is pi. So, phase difference will be--pi,0,pi,0 Instant phase will be, pi,pi,0,0....Easy!!
bit error is same for QPSK and BPSK. :
See the question "What is QPSK". If you want the difference between QPSK and some other modulation system, you'll need to name the other one.
the phase shift allowed in OQPSK is 900 whereas in QPSK it is 1800 . QPSK is used in uplink whereas OQPSK is used in downlink.
Qpsk has lesser bw than dpsk but has more probability in error than dpsk.
in psk,we use only single type of phase shift for a bit transition. in qpsk,we use 4 types of phase shifts for a bit transition.
BPSK=> 1.The BPSK stands for “Binary Phase-shift keying”. 2.DPSK is a not a method of BPSK, where there is no reference phase signal. 3.amplitude shift keying 4.lesser bandwidth more probability error DPSK=> 1.The DPSK stands for “Differential phase-shift keying”. 2.DPSK is a method of BPSK, where there is no reference phase signal. 3.It is one type of phase modulation used to transmit data by altering the carrier wave’s phase. 4.greater bandwidth probability error less
in qpsk we are using phases for representation of messages while in qam we hav amplitude levels. in qpsk 2 bits per symbol is used with four different phases. in qam depanding on type i.e 16 qam,64 qam,256 qam how many amplitude levels to be used accordingly i.e 16,64,256. sonender kumar
How to Generate digital data for bpsk modulation?
QPSK = Quadrature Phase Shift Keying In QPSK amplitude are not much.so the carrier is constant. transmission rate is higher when compared with PSK
QPSK require less bandwidth compare to psk
In abs. PSK only instant phase for the incoming bits are considered. For DPSK, the difference between previous phase and the present phase is considered. Example: If BPSK is used, then for 0 if phase if pi and for 1 it is 0, then for abs. BPSK the phase states for the bit stream 1010 will be 0,pi,0,pi for DPSK, we assume initial phase is zero and a rule that , if incoming bit is zero, then phase difference is 0 and if it is 1 then, phase difference is pi. So, phase difference will be--pi,0,pi,0 Instant phase will be, pi,pi,0,0....Easy!!
QPSK is used in CDMA because it helps achieve higher data rates. It is much better than simple PSK.