摘要:
Systems and methods for upgrading selected wavelengths in a WDM link to higher data rates at minimal expense are provided. Error correction coding techniques are employed such that the data encoded onto the upgraded wavelengths experiences higher coding gain than that experienced by data encoded on the non-upgraded wavelengths. This increases receiver sensitivity without the use of expensive opto-electronic components. In one embodiment, Reed-Solomon coding is employed on the upgraded wavelengths and no error correction coding is employed on the remaining wavelengths. These techniques may also be applied to new WDM links carrying channels with disparate bit rates.
摘要:
In a network including access points, via which communication units can connect to the network, wherein each of the access points belongs to a zone, a method comprising the steps of assigning a message type to each of the zones in the network; receiving from the communication unit a query message for each zone, where the query message for each zone is of the message type assigned to that zone; filtering the query messages at an access point, via which the communication unit is connected to the network, so that only the query message of the message type, which is assigned to the zone to which the access point belongs, is allowed to pass through; and determining the zone, to which the access point belongs, depending on the query message allowed to pass through in the step of filtering.
摘要:
A layer is disclosed for use in combination with an insert half to provide a sealing around a cable, wire or tube in a frame. The layer has the shape of an elongated circular arc with a first end and a second end. In at least one embodiment, the layer is provided with at least one indexing device arranged at the first and/or the second end of the layer.
摘要:
In a network including access points, via which communication units can connect to the network, wherein each of the access points belongs to a zone, a method comprising the steps of assigning a message type to each of the zones in the network; receiving from the communication unit a query message for each zone, where the query message for each zone is of the message type assigned to that zone; filtering the query messages at an access point, via which the communication unit is connected to the network, so that only the query message of the message type, which is assigned to the zone to which the access point belongs, is allowed to pass through; and determining the zone, to which the access point belongs, depending on the query message allowed to pass through in the step of filtering.
摘要:
An add/drop node of an optical WDN-network which has two fiber paths for light of a plurality of channels propagating in opposite directions comprises two add/drop modules (231, 23r) for each of the channels. All the modules are identically constructed. Each module comprises an add device (251, 25r) for adding light to one of the paths and a drop device (27r, 271) for deflecting a portion of light from a second one of the paths. A module comprises a house (41) enclosing the add device and the drop device. A first fixed connector (53, 73) is attached to the house for connection in the first path and to a an optical fiber (45, 65) which extends freely from the house and has a first free connector (43, 63) at its free end to be attached to the fixed connector of a neighboring add/drop module for continuing the first path through the considered add/drop module to the neighboring module. In the same way a second fixed connector is attached to the house for connection in the second path and to a second optical fiber which extends freely from the house and has a second free connector at its free end to be attached to the fixed second connector of a neighboring add/drop module for continuing the second path through the considered add/drop module to the neighboring module.
摘要:
An optical fiber network of WDM type comprises two fibers which carry light signals propagating in opposite directions and which are arranged in a ring configuration. One standby link between two neighboring nodes is inactive but is made active if an active link fails. An add and drop node used in the network has band blocking filters connected in a fiber between a drop coupler and an add coupler, taking out a share of the light power in each direction to be received through bandpass filters in receivers and adding new wavelength channels produced in transmitters, respectively. Switches are used for receiving and transmitting on the wavelength channels in correct directions. The positions of the switches can be changed when the inactive link has to become one of the two active links directly connected to the node. A very efficient use of the wavelength channels in the network can then be achieved for nodes having a minimum of in-line components, and particularly, a minimum of in-line filtering components.
摘要:
The invention relates to a method and to an arrangement for estimating total noise power (k·P&lgr;) at a specified point in a WDM-system which includes a predetermined number of amplifiers (51), and which is designed to transmit data in channels at mutually different signal wavelengths within a specific wavelength region. The method comprises the steps of: measuring total optical power (Pouttot) at said specific point. Filtering wavelength power (P&lgr;) out from the total optical power (Pouttot) at a given measuring wavelength (&lgr;m) within the transmitted wavelength range but outside the signal wavelength. The wavelength power (P&lgr;) is multiplied by a constant (k) which gives the total noise power (k·P&lgr;) at said specified point.
摘要:
A communication network has a flexible bi-directional bus architecture (FBDNA) and is arranged as a ring structure. Each node of the network has at least one on/off node switch, i.e., a switch that permits or blocks transmission around what would otherwise be a ring. If the network has one node switch per node, one node switch is set initially off to avoid problems with circulating amplified spontaneous emission (ASE) normally associated with a ring structure. If a fiber break occurs, the node switch (or node switches) in the node (or nodes) next to the break and on the same side of the node as the break switches off, and the node switch that was off before the break switches on, permitting the network to operate largely as before. If the network has two node switches per node, two node switches next to each other in neighboring nodes are initially set off, and if a cable break occurs, both node switches around a break switch off, and the node switches that were initially off switch on. The network provides protective switching of traffic and solves the problem of circulating ASE in a simple and economical way. The network also permits wavelength reconfiguration to reduce the number of required wavelengths.
摘要:
Device for selective climate control in vehicle cabins having a first air-vent duct (18) and a second air-vent duct (22) on respective sides or different zones in a vehicle cabin. The duct temperature on each side is measured and the duct adjustment is regulated by inner feedback control circuits. The cabin temperature (Tc1, Tc2 resp.) on both sides is measured, preferably at approximately head level, and fed to outer control circuits which determine the desired duct temperature as the deviation between the desired cabin temperatures (Tcs1, Tcs2 resp.) set by means of separate control knobs (38, 44) and the measured cabin temperatures (Tc1, Tc2 resp.). Desired duct temperature signals (Dts1, Dts2 resp.) are connected as input signals to respective inner control circuits.