How can I create a digital data eye pattern diagram?

[pekos]

I need to create a simulation tool (for educational purposes) which will simulate a basic digital communication system (Tx, channel (+noise), receiver). My first step is to create an eye pattern diagram which displays data transmitted by the source (PRBS or user specific 8-bit word). How can I create this VI (eye pattern diagram)? I know the theory behind (need to extract the clock info with PLL[phase locked loop] probably, but I need more in depth information)

[Ben]

Hi Pekos,

Please elaborate or post a picture that would help us (well maybe just me) understand what you mean by an "eye pattern diagram".

Ben

[DiegoF]

Hi,

From what I've researched on the web, in an eye-pattern diagram segments of the signal are superimposed in the same time-amplitude graph. The segments have a time length multiple of the 1/transfer rate (bit time in some cases). Also, the triggering of the acquisition plays an important role. The idea is to be able to look at whole transmition symbol (bit).

There's not much information on the web, and I haven't worked with eye pattern diagrams. The information I found is at:

http://www.leader.co.jp/english/gijyutu/gij_d1.html

http://www.finisar.com/news/franks.news.php?franks_news_id=6

http://www.altera.com/products/devices/apex/features/apx-eye_diag.html

National Instrument does not have anything in particular that would acquire a eye
pattern diagram. You could program an application that would do it, but we don't have anything ready-made. An eye pattern diagram is just a form of representation of the acquire data. So it's just a matter of programming how to represent the data.

I don't know if you're using LabVIEW or other programming enviroment, or if you want to acquire a signal and then present it in an eye-pattern diagram.

DiegoF
National Instruments

[pekos]

A big thanx for Diego. However I already have this kind of info by other sites, but I would like to know how you found these sites as I never came up with these when I searched with google,altavista,yahoo, and lycos. Is there any search engine that deals with electronic engineering matters and/or software programming issues? Thanx again Diego.....

[DiegoF]

Hi,

I don't remember the exact way, but I just used Google.

I did two searches. One for "eye pattern diagram" and the other for "eye pattern" (include the quotes).

These web sites are not the first hits, but you can go through the results fairly quickly.

DiegoF.