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Analog data is carried by an alternating current. If we were to graphically represent alternating current, it would appear as a wave, with voltage bouncing above and below the zero level. There are three factors to consider: frequency, amplitude, and phase.
Frequency is the rate at which the current alternates above and below the zero current level. When the current rises above zero, dips below zero and then returns to zero, we say the current has completed one "cycle". The name applied to the number of cycles per second is Hertz (Hz). Therefore, if there are 500 cycles per second for an analog signal, we say the frequency is 500 Hertz (500 Hz).
Amplitude would be viewed as the height (peak) and the depth (trough) of the graphic wave. As analog data travels over distance, the amplitude of the wave decreases. This characteristic is called "attenuation". The amplitude of analog waves is measured in watts, amps or volts. The measurement decibel is often used to describe the power of a signal.
Finally, phase describes the difference in the start of the cycle of one signal to the start of the cycle of another. One signal acts as a reference signal, the other signal is the phased signal. The level of non-synchronization is measured in degrees. If a signal is 180º out of phase, it means that as the reference signal reaches zero voltage following a peak, the phased signal begins. Thus as the reference signal is peaking, the phased signal is (for lack of a better term) troughing. The figure below illustrates this more clearly.
Phasing is the result of creating a signal out of sync with a reference signal.Altering the frequency, amplitude or phase of a signal is called modulation
.ASK:AM radio is produced by taking a basic signal (radio wave) and modulating its amplitude according to another signal (i.e. voice and music). AM stands for Amplitude Modulation. We may use the same technology for carrying computer data as well. For digital data, it's called Amplitude-Shift Keying (ASK).
Figure 5.2: Amplitude Modulation can be used to encode data in analog signals.
FSK: FM radio is produced by taking a basic signal (radio wave) and modulating its frequency according to another signal (i.e. music and voice). In this case, FM is an acronym for Frequency Modulation. In the digital data realm, the same technology can be applied using Frequency-Shift Keying(FSK). Fig illustrates a couple of examples.
Figure 5.3: Frequency Modulation may be used to encode data into an analog signal as well.
PSK:
Figure 5.4: Phase Modulation can be used to encode data in an analog signal. The amplitude is varied in some technologies.
In analyzing methods for carrying digital data, Amplitude-Shift Keying is fairly easy to accomplish. On the other hand, any kind of amplitude modulated signal is very susceptible to outside interference. Therefore, ASK is not really suitable for transmission over long distances.
Just as FM radio is not generally affected by weather, neither are FSK transmissions. In spite of this, Frequency-Shift Modulation is seldom used for transmission over high-speed lines as the technology does not allow as many bits per second throughput as PSK does.
Phase-Shift Keying technology is what is utilized by most high speed modern modems. It allows four different phases (in degrees) to encode data. The result is a potential for 600 phase shifts per second. Each phase shift represents a certain combination of 2 bits (i.e. 00 01 10 or 11). It then logically follows that since two bits are transmitted per phase shift and there are 600 phase shifts per second.
PSK is very resistant to external interference as it enjoys most of the same characteristics that FM or FSK devices do. The signals encoded using PSK may be used for synchronization purposes as well for the sender and receiver.
What else can I help you with?
Which modulation is used with digital data?
-- PSK -- DPSK -- 16, 32, 64, 128, and 256 QAM
Why Qpsk?
QPSK is used in CDMA because it helps achieve higher data rates. It is much better than simple PSK.
How can you Change your Passport application from normal to Tatkal scheme in India?
In case you want any change in submitted applicationdetails, please visit Passport Seva Kendra (PSK).
What is the wideband semiconductor?
The WSC6100 Demodulator Monitor & Analysis system provides satellite and microwave communication managers with real-time monitoring and analysis reports by recovering PSK and QAM symbols from digitally modulated Intermediate Frequency (IF) signals.
Compear fsk and psk?
fsk and psk
What are modulation techniques in satellite communication?
frequency modulation, preferably.
Advantages of psk over fsk and ask?
PSK (Phase Shift Keying) is advantageous over FSK (Frequency Shift Keying) and ASK (Amplitude Shift Keying) because it provides higher data rates and better spectral efficiency. PSK is less susceptible to noise and interference since phase changes are more discernible than frequency or amplitude changes. PSK also allows for easier implementation in digital communication systems.
Why psk is better then fsk and ask?
Phase Shift Keying (PSK) is often considered superior to Frequency Shift Keying (FSK) in terms of bandwidth efficiency and resilience to noise. PSK encodes data by altering the phase of a carrier signal, allowing for higher data rates within the same bandwidth compared to FSK, which changes the frequency. Additionally, PSK is less susceptible to amplitude variations, making it more reliable in environments with signal degradation. Overall, PSK is preferred in many digital communication systems for its efficiency and robustness.
What is the advantage and disadvantage of fsk fsk and psk modulation?
advantages of fsk arelow noise,since amplitude is constantpower requirement is constantoperates in virtually any wires availablehigh data rateused in long distance communicationeasy to decodegood sensitivity
According to following constellation diagram if bit rate is 6400 bps what is the Baud Rate?
From the given constellation diagram determine whether its ASK, FSK, PSK or n-QAM. Then use the appropriate value of r to get Baud Rate = Bit Rate/r.
Difference between absolute PSK and differential 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!!
What the compare between psk and qpsk?
PSK (Phase Shift Keying) and QPSK (Quadrature Phase Shift Keying) are both digital modulation techniques used in communication systems. The main difference is that QPSK uses four distinct phase shifts, while PSK uses two. Therefore, QPSK can transmit twice as much data as PSK in the same amount of bandwidth.
What is the difference between pm and psk?
PM (Phase Modulation) and PSK (Phase Shift Keying) are both modulation techniques used in communication systems, but they have distinct applications. PM varies the phase of a carrier signal in accordance with the amplitude of the input signal, while PSK encodes data by changing the phase of the carrier signal among a finite set of values. Essentially, PM is more analogue in nature, while PSK is digital, making PSK commonly used for data transmission in digital communications.
Why fsk does not used for high speed mode?
Frequency Shift Keying (FSK) is generally not used for high-speed data transmission because it requires a larger bandwidth compared to other modulation techniques like Phase Shift Keying (PSK) or Quadrature Amplitude Modulation (QAM). The inherent nature of FSK, which relies on shifting between discrete frequencies, can limit the data rate and increase susceptibility to noise and interference. Additionally, as data rates increase, the frequency separation needed for reliable detection may become impractical, leading to reduced efficiency and performance in high-speed applications.
What is the advantage of qam over ask and psk?
PSK and QAM modulation have two advantages over ASK: *They are not as susceptible to noise. *Each signal change can represent more than one bit PSK Disadvantage more complex signal detection / recovery process, than in ASK and FSK QAM advantage: · data rate = 2 bits per bit-interval! · higher data rate than in PSK (2 bits per bit interval), while bandwidth occupancy remains the same • 4-PSK can easily be extended to 8-PSK, i.e. n-PSK • however, higher rate PSK schemes are limited by the ability of equipment to distinguish small differences in phase uses "two-dimensional" signaling • original information stream is split into two sequences that consist of odd and even symbols · PSK modulators are often designed using the QAM principle, but are not considered as QAM since the amplitude of the modulated carrier signal is constant. QAM is used extensively as a modulation scheme for digital telecommunication systems. Arbitrarily high spectral efficiencies can be achieved with QAM by setting a suitable constellation size, limited only by the noise level and linearity of the communications channel. · Noise immunity of QAM is very high. · QAM is best suitable for high bit rates. · Low error probability. · Baud rate is half the bit rate therefore more effective utilization of the available bandwidth of the transmission channel.
Why does your dsi ask you a security key is needed to connect to this access point enter the security key then tap ok and What is the security key?
The security key is the password for the wireless router. It'll show up if the wireless encryption is : WEP WPA-PSK (TKIP) WPA2-PSK(TKIP) WPA-PSK (AES) WPA2-PSK (AES).
