Navigation Home / Tags / drop

ranking Sort Sort   |   date Sort Sort   |   member Sort Sort

Date Submitted Fri. Jul. 12th, 2013 6:41 AM
Revision 1
Syntax Master claireling
Tags add | con | Cross | drop | Filters | multiplexer | optical | WDM
Comments 0 comments
The OADM, or optical add drop multiplexer, is a gateway into and out of a single mode fiber. In practice, most signals pass through the device, but some would be ˇ°droppedˇ± by splitting them from the line. Signals originating at that point can be ˇ°addedˇ± into the line and directed to another destination. An OADM may be considered to be a specific type of optical cross-connect, widely used in wavelength division multiplexing systems for multiplexing and routing fiber optic signals. They selectively add and drop individual or sets of wavelength channels from a dense wavelength division multiplexing (DWDM) multi-channel stream. OADMs are used to cost effectively access part of the bandwidth in the optical domain being passed through the in-line amplifiers with the minimum amount of electronics.

OADMs have passive and active modes depending on the wavelength. In passive OADM, the add and drop wavelengths are fixed beforehand while in dynamic mode, OADM can be set to any wavelength after installation. Passive OADM uses WDM filter, fiber gratings, and planar waveguides in networks with WDM systems. Dynamic OADM can select any wavelength by provisioning on demand without changing its physical configuration. It is also less expensive and more flexible than passive OADM. Dynamic OADM is separated into two generations.

A typical OADM consists of three stages: an optical demultiplexer, an optical multiplexer, and between them a method of reconfiguring the paths between the optical demultiplexer, the optical multiplexer and a set of ports for adding and dropping signals. The optical demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by a cross connection panel or by optical switches which direct the wavelengths to the optical multiplexer or to drop ports. The optical multiplexer multiplexes the wavelength channels that are to continue on from demultipexer ports with those from the add ports, onto a single output fiber.

Physically, there are several ways to realize an OADM. There are a variety of demultiplexer and multiplexer technologies including thin film filters, fiber Bragg gratings with optical circulators, free space grating devices and integrated planar arrayed waveguide gratings. The switching or reconfiguration functions range from the manual fiber patch panel to a variety of switching technologies including microelectromechanical systems (MEMS), liquid crystal and thermo-optic switches in planar waveguide circuits.

CWDM and DWDM OADM provide data access for intermediate network devices along a shared optical media network path. Regardless of the network topology, OADM access points allow design flexibility to communicate to locations along the fiber path. CWDM OADM provides the ability to add or drop a single wavelength or multi-wavelengths from a fully multiplexed optical signal. This permits intermediate locations between remote sites to access the common, point-to-point fiber message linking them. Wavelengths not dropped, pass-through the OADM and keep on in the direction of the remote site. Additional selected wavelengths can be added or dropped by successive OADMS as needed.

FiberStore provides a wide selection of specialized OADMs for WDM system. Custom WDM solutions are also available for applications beyond the current product designs including mixed combinations of CWDM and DWDM.
Date Submitted Thu. Feb. 7th, 2013 11:58 AM
Revision 1
Helper hexahow
Tags country | Down | drop | geolocation | List
Comments 0 comments
The following codes populate the country list into dropdown box based on browser's languages. The country information is getting from
Date Submitted Mon. Aug. 11th, 2008 11:50 PM
Revision 1
Scripter Fordiman
Tags analytics | drop | google | in | JavaScript
Comments 1 comments
Forgive the formality here; this is one of my professional scripts.

Analyte 1.0 (c) 2008 Bryan Elliott
Simplify inclusion of Google Analytics into any site, add GA tracking to non-HTML links, and reduce 'blocking' action of Google Analytics scripts.


Unlimited license granted to Abacus Studios, Inc. and I-Site, Inc.
All other parties licensed under CC-BY-SA-3.0:

Creative Commons Attribution / Share Alike 3.0 US
Fulltext and synopsis at

This license need not appear in minified or otherwise compressed forms
of this script, so long as the script is in active use by a web site or
application, and no other credit is claimed.
Date Submitted Fri. Aug. 25th, 2006 7:46 PM
Revision 1
Helper psykoprogrammer
Tags .Net | C | drag | drop | treeview
Comments 2 comments
Below is a bit of code which sets up drag and drop in a treeview. This is handy for if you have a list of items that can be sorted by the user.

Here is a bit of code to demonstrate how to do this. First create a new Windows executable project. Drop a TreeView component on the form, and let's name it 'myTree' for this demonstration. Go ahead and populate it with some dummy data; enough data to see the dragging and dropping in action. You will need a variable global to the form's scope.

private TreeNode sourceNode;

This is used to track the item we are dragging in our TreeView. Then define the event handlers listed below.