Eye pattern

Graphical eye pattern showing an example of two power levels in an OOK modulation scheme. Constant binary 1 and 0 levels are shown, as well as transitions from 0 to 1, 1 to 0, 0 to 1 to 0, and 1 to 0 to 1.

In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital data signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep. It is so called because, for several types of coding, the pattern looks like a series of eyes between a pair of rails.

Several system performance measures can be derived by analyzing the display. If the signals are too long, too short, poorly synchronized with the system clock, too high, too low, too noisy, or too slow to change, or have too much undershoot or overshoot, this can be observed from the eye diagram. An open eye pattern corresponds to minimal signal distortion. Distortion of the signal waveform due to intersymbol interference and noise appears as closure of the eye pattern. ^[1][2][3]

Example

• 

  The eye diagram of a binary PSK system

• 

  The eye diagram of the same system with multipath interference effects added

• 

  Eye diagram of a 4 level ASK signal

Measurements

There are many measurements that can be obtained from an Eye Diagram^[4]:

Amplitude Measurements

• Eye Amplitude
• Eye Crossing Amplitude
• Eye Crossing Percentage
• Eye Height
• Eye Level
• Eye SNR
• Quality Factor
• Vertical Eye Opening

Time Measurements

• Deterministic Jitter
• Eye Crossing Time
• Eye Delay
• Eye Fall Time
• Eye Rise Time
• Eye Width
• Horizontal Eye Opening
• Peak-to-Peak Jitter
• Random Jitter
• RMS Jitter
• Total Jitter

Interpreting Measurements

Eye-diagram feature	What it measures
Eye opening (height, peak to peak)	Additive noise in the signal
Eye overshoot/undershoot	Peak distortion due to interruptions in the signal path
Eye width	Timing synchronization & jitter effects

See also

• Constellation diagram
• Signal integrity
• Raised-cosine filter

Notes

1. ^ Christopher M. Miller "High-Speed Digital Transmitter Characterization Using Eye Diagram Analysis". 1266 Hewlett-Packard Journal 45(1994) Aug., No,4, pp. 29-37.
2. ^  This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).
3. ^ John G Proakis, Digital Communications 3rd ed, 2001
4. ^ "Matlab's help file description of how to use the Eye Diagram Functions in the Communications Toolbox". http://www.mathworks.com/access/helpdesk/help/toolbox/comm/index.html?/access/helpdesk/help/toolbox/comm/ref/commscope.eyediagram.html. 

References

• "HP E4543A Q Factor and Eye Contours Application Software" (PDF). 1999. http://cp.literature.agilent.com/litweb/pdf/E4543-90004.pdf. 
• "Agilent 71501D Eye-Diagram Analysis User’s Guide" (PDF). http://cp.literature.agilent.com/litweb/pdf/70874-90023.pdf. 

External links

• Ruckerbauer, Hermann. "An Eye is Born". http://www.youtube.com/watch?v=my7CI84le5g.  Gives an example video of construction of an eye pattern

This article related to telecommunications is a stub. You can help Wikipedia by expanding it.v · Categories: Data transmission Telecommunications stubs Wikimedia Foundation. 2010. Игры ⚽ Нужна курсовая? Extinction ratio Telecommunications facility Look at other dictionaries: eye pattern — noun An oscilloscope display of a data signal passed through a transmission line, clocked synchronously to the data symbols …   Wiktionary Eye color — is a polygenic trait and is determined by the amount and type of pigments in the eye s iris.Wielgus AR, Sarna T. Melanin in human irides of different color and age of donors. Pigment Cell Res. 2005 Dec; 18(6):454 64. PMID 16280011.] Prota G, Hu… …   Wikipedia Eye tracking — is the process of measuring either the point of gaze ( where we are looking ) or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual… …   Wikipedia Pattern 1853 Enfield — Rifle Musket 1853 Enfield Rifle Musket Type Rifled Musket Place of origin …   Wikipedia Eye Movement Desensitization and Reprocessing — (EMDR) is a form of psychotherapy that was developed to resolve symptoms resulting from disturbing and unresolved life experiences. It uses a structured approach to address past, present, and future aspects of disturbing memories. The approach… …   Wikipedia Eye dialect — is the use of non standard spelling for speech to draw attention to pronunciation. The term was originally coined by George P. Krapp to refer to the literary technique of using non standard spelling that implies a pronunciation of the given word… …   Wikipedia eye|let — «Y liht», noun, verb. –n. 1. a small, round hole for a lace or cord to go through, as in most shoes. 2. a metal ring around such a hole to strengthen it. 3. a hole to look through; peephole. 4. a small, round hole with stitches around it, used to …   Useful english dictionary eye|ground — «Y GROWND», noun. the fundus of the eye, as viewed through an ophthalmoscope; the back part of the interior of the eyeball: »More emphasis is being placed upon the examination of the eyegrounds…as an index of the general arteriolar pattern… …   Useful english dictionary eye, human — ▪ anatomy Introduction  specialized sense organ capable of receiving visual images, which are then carried to the brain. Anatomy of the visual apparatus Structures auxiliary to the eye The orbit       The eye is protected from mechanical injury… …   Universalium eye disease — Introduction  any of the diseases or disorders that affect the human eye (eye, human).       This article briefly describes the more common diseases of the eye and its associated structures, the methods used in examination and diagnosis, and the… …   Universalium 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”