DSP: Simulator
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at a precise time.
There are three major classes of digital modulation techniques used for transmission of digitally represented data:
Amplitude-shift keying (ASK)
Frequency-shift keying (FSK)
Phase-shift keying (PSK)
BPSK is the simplest form of phase shift keying (PSK). It uses two phases which are separated by 180. It does not particularly matter exactly where the constellation points are positioned, at 0° and 180°. Therefore, it handles the highest noise level or distortion before the demodulator reaches an incorrect decision. That makes it the most robust of all the PSKs. It is, however, only able to modulate at 1 bit/symbol and so is unsuitable for high data-rate applications.
QPSK uses four points on the constellation diagram, equispaced around a circle. With four phases, QPSK can encode two bits per symbol,with Gray coding to minimize the bit error rate (BER). Offset quadrature phase-shift keying (OQPSK) is a variant of phase-shift keying modulation using four different values of the phase to transmit. It is sometimes called staggered quadrature phase-shift keying (SQPSK).
DPSK is a common form of phase modulation that conveys data by changing the phase of the carrier wave. As mentioned for BPSK and QPSK there is an ambiguity of phase if the constellation is rotated by some effect in the communications channel through which the signal passes. This problem can be overcome by using the data to change rather than set the phase.
Manchester encoding
In data transmission, Manchester encoding is a form of digital encoding in which data bits are represented by transitions from one logical state to
the other. This is different from the more common method of encoding, in which a bit is represented by either a high state such as +5 volts or a
low state such as 0 volts.
Duobinary coding
It is possible to transmit f sysmbols/sec with zero ISI, using the theoretical minimum BW of f/2 Hz, without infinitely sharp filters. The basic idea
is to introduce some controlled amount of ISI in to the data stream rather than trying to eliminate it completely.
There are three major classes of digital modulation techniques used for transmission of digitally represented data:
Amplitude-shift keying (ASK)
Frequency-shift keying (FSK)
Phase-shift keying (PSK)
BPSK is the simplest form of phase shift keying (PSK). It uses two phases which are separated by 180. It does not particularly matter exactly where the constellation points are positioned, at 0° and 180°. Therefore, it handles the highest noise level or distortion before the demodulator reaches an incorrect decision. That makes it the most robust of all the PSKs. It is, however, only able to modulate at 1 bit/symbol and so is unsuitable for high data-rate applications.
QPSK uses four points on the constellation diagram, equispaced around a circle. With four phases, QPSK can encode two bits per symbol,with Gray coding to minimize the bit error rate (BER). Offset quadrature phase-shift keying (OQPSK) is a variant of phase-shift keying modulation using four different values of the phase to transmit. It is sometimes called staggered quadrature phase-shift keying (SQPSK).
DPSK is a common form of phase modulation that conveys data by changing the phase of the carrier wave. As mentioned for BPSK and QPSK there is an ambiguity of phase if the constellation is rotated by some effect in the communications channel through which the signal passes. This problem can be overcome by using the data to change rather than set the phase.
Manchester encoding
In data transmission, Manchester encoding is a form of digital encoding in which data bits are represented by transitions from one logical state to
the other. This is different from the more common method of encoding, in which a bit is represented by either a high state such as +5 volts or a
low state such as 0 volts.
Duobinary coding
It is possible to transmit f sysmbols/sec with zero ISI, using the theoretical minimum BW of f/2 Hz, without infinitely sharp filters. The basic idea
is to introduce some controlled amount of ISI in to the data stream rather than trying to eliminate it completely.
Document was informative
ReplyDeletegreat content, good to know about DPSK, QPSK
ReplyDeletegreat to know about these techniques
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