You can also derive jitter from power-spectral-density, or phase-noise, measurements. Table 1 presents these various measures of jitter for a 155.52-MHz system clock. Expressed in decibels relative to one unit interval (dB UI ), jitter power in this case is 10log(0.0000049)=–53.1 dB UI. For the above case of 100-psec jitter, you find the rms jitter power by dividing the peak-to-peak jitter by seven and then squaring the result: 0.01555/7) 2 =0.0000049 UI 2. A reasonable expectation of peak-to-peak jitter, and a standard industry number, is approximately 7, or seven times the rms value. To define jitter power, you typically use rms, 1-sigma ( ) measurements. All three numbers describe the same amount of jitter. In this case, 100 psec of jitter=0.01555 UIs=5.598°of peak-to-peak jitter. One UI equals the period of the signal, which you can then translate to time and degree units as follows: 1/155.52X10 6 UIs=6.43 nsec=360°. As a power measurement in units of radians or unit intervals squared, which is often expressed in decibels relative to one cycle squared (Reference 2).Īs an example of these units, consider a clock rate of 155.52 MHz.Jitter expressed in units of time describes the magnitude of the jitter in appropriate orders of magnitude, usually picoseconds. Jitter expressed in degrees describes the magnitude of the jitter in units of degree for which one cycle equals 360°. Jitter expressed in UIs describes the magnitude of the jitter as a decimal fraction of one UI. One UI is one cycle of the clock frequency, which is the normalized clock period. You can quantitatively express jitter in the following ways: All other jitter that this discussion refers to is stochastic in nature, and you may describe it only as a random variable with respect to time. Pattern jitter is deterministic jitter that you can attribute to a unique source. When you view this type of jitter in the time domain, it appears as multiple modes of jitter. For example, pattern, or pattern-dependent, jitter is sometimes called “flanging.” This type of jitter is not random it generally results from subharmonics. It is important to understand the definitions of jitter and the quantitative ways that you can express jitter. The PD power port helps users in passing up to 100W of power from the charger to the host device (laptop/tablet/phone) so that users can simultaneously charge their device while using those multiple connections.Figure 2 An eye diagram is a cumulative graphical portrait edge placement due to noise of jitter and can reveal ideal (a), typical (b), and corrupted (c) data streams. There’s also a dual memory card reader slot for standard SD cards and micro/TF cards for transferring data from phones and cameras. The dock has an audio jack that allows users to plug in their headsets for calls and entertainment or route to a home-theatre system. It has a 100mbps LAN/Ethernet port that allows the smartphone, tablet or laptop to hold stable and higher-speed networking and internet connections. The Mport 11C also hosts an HDMI (4K) and VGA (1080p) port where it can connect up to two additional displays to extend the desktop to multiple monitors. These include input devices like– keyboard, mouse, gamepad, fingerprint readers, cameras, etc, or other USB peripherals such as audio DACs, printers, scanners, storage drives, and more. The 11-in-1 hub expands a single USB-C port on your host laptop, tablet, or smartphone to four USB 3.0 Type-A ports using which users can simultaneously connect a plethora of devices. Portronics Mport 11C is a multifunctional hub that hosts both– USB-C and USB Type-C ports.
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