Search results
Results From The WOW.Com Content Network
The delay skew test is used to find the difference in propagation delay between the fastest and slowest set of wire pairs. An ideal skew is between 25 and 50 nanoseconds over a 100-meter cable. The lower this skew the better; less than 25 ns is excellent, but 45 to 50 ns is marginal.
Propagation delay is equal to d / s where d is the distance and s is the wave propagation speed. In wireless communication, s=c, i.e. the speed of light. In copper wire, the speed s generally ranges from .59c to .77c. [3] [4] This delay is the major obstacle in the development of high-speed computers and is called the interconnect bottleneck in ...
The cables are typically made with copper wires measured at 22 or 24 American Wire Gauge (AWG) (0.644 or 0.511 mm²), [5] with the colored insulation typically made from an insulator such as polyethylene or FEP and the total package covered in a polyethylene jacket.
The phase velocity at which electrical signals travel along a transmission line or other cable depends on the construction of the line. Therefore, the wavelength corresponding to a given frequency varies in different types of lines, thus at a given frequency different conductors of the same physical length can have different electrical lengths.
A time-domain reflectometer; an instrument used to locate the position of faults on lines from the time taken for a reflected wave to return from the discontinuity.. A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line, or if ...
Much of the development of delay lines during World War II was motivated by the problems encountered in radar systems. In 1944, Madison G. Nicholson applied for a general patent on magnetostrictive delay lines. He recommended their use for applications requiring delays or measurement of intervals in the 10 to 1000 microseconds time range. [10]
It is only after this round-trip delay that the short can be detected by the TDR. With knowledge of the signal propagation speed in the particular cable-under-test, the distance to the short can be measured. A similar effect occurs if the far end of the cable is an open circuit (terminated into an infinite impedance).
The group delay is a convenient measure of the linearity of the phase with respect to frequency in a modulation system. [3] [4] For a modulation signal (passband signal), the information carried by the signal is carried exclusively in the wave envelope. Group delay therefore operates only with the frequency components derived from the envelope.