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One of the causes of intersymbol interference is multipath propagation in which a wireless signal from a transmitter reaches the receiver via multiple paths. The causes of this include reflection (for instance, the signal may bounce off buildings), refraction (such as through the foliage of a tree) and atmospheric effects such as atmospheric ducting and ionospheric reflection.
Not every filter can be used as a pulse shaping filter. The filter itself must not introduce intersymbol interference — it needs to satisfy certain criteria. The Nyquist ISI criterion is a commonly used criterion for evaluation, because it relates the frequency spectrum of the transmitter signal to intersymbol interference.
The +1 and -1 states should have equal amplitude. There should be smooth transitions from the 0 state to the +1 and -1 states, however there should be no direct transitions from the -1 to +1 state (which would indicate the signal is PAM-3 rather than MLT-3). Eye pattern of a 125 Mbit/s MLT-3 signal
The raised-cosine filter is a filter frequently used for pulse-shaping in digital modulation due to its ability to minimise intersymbol interference (ISI). Its name stems from the fact that the non-zero portion of the frequency spectrum of its simplest form ( β = 1 {\displaystyle \beta =1} ) is a cosine function, 'raised' up to sit above the f ...
[16] C++, Python, and JavaScript: GPLv3 Light scattering from a multilayered sphere based on the algorithm by W Yang. [17] Very robust and stable, slower than Toon and Ackerman. Evaluate integral parameters and angular patterns, near-field and power flow streamlines plotting. Has a compilation option to use Boost.Multiprecision for higher accuracy.
In digital communications, a turbo equalizer is a type of receiver used to receive a message corrupted by a communication channel with intersymbol interference (ISI). It approaches the performance of a maximum a posteriori (MAP) receiver via iterative message passing between a soft-in soft-out (SISO) equalizer and a SISO decoder. [1]
A tutorial on the significance of Cyclic Prefix (CP) in OFDM Systems Archived 2023-10-05 at the Wayback Machine. Siemens demos 360 Mbit/s wireless; An Introduction to Orthogonal Frequency-Division Multiplex Technology; Short Introduction to OFDM – Tutorial written by Prof. Debbah, head of the Alcatel-Lucent Chair on flexible radio.
A complete PPM frame is about 22.5 ms (can vary between implementation), and signal low state is always 0.3 ms. It begins with a start frame (high state for more than 2 ms). Each channel (up to 8) is encoded by the time of the high state plus the lower state. (PPM high state + 0.3 = servo PWM pulse width).