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English translation: main center of demand


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23:39 Mar 11, 2002
German to English translations [PRO]
German term or phrase: Bedarfsschwerpunkt
Ausgestattet mit Breitband-Glasfaseranschluß an allen Bedarfsschwerpunkten
Barbara Wiegel
Local time: 15:56
English translation:main center of demand
at the main centers of demand.

Selected response from:

Elisabeth Ghysels
Local time: 15:56
Grading comment
Thank you very much!
4 KudoZ points were awarded for this answer


Summary of answers provided
4 +2main center of demand
Elisabeth Ghysels
4stress points /(network? stress points) {at pop intersections?}Deb Phillips



9 mins   confidence: Answerer confidence 4/5Answerer confidence 4/5 peer agreement (net): +2
main center of demand

at the main centers of demand.


    Reference: http://www.fao.org/docrep/x5395e/x5395e04.htm
Elisabeth Ghysels
Local time: 15:56
PRO pts in pair: 971
Grading comment
Thank you very much!

Peer comments on this answer (and responses from the answerer)
agree  Dr. Stephan Pietzko
20 mins

agree  Endre Both
8 hrs
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1 hr   confidence: Answerer confidence 4/5Answerer confidence 4/5
stress points /(network? stress points) {at pop intersections?}

The most basic fiber optic measurement is optical power from the end of a fiber. This measurement is the basis for loss measurements as well as the power from a source or at a receiver. ...The first source of error is optical coupling. Light from the fiber is expanding in a cone. It is important that the detector to fiber geometry be such that all the light from the fiber hits the detector, otherwise the measurement will be lower than the actual value. But every time light passes through a glass to air interface, such as the window on the detector, a small amount of the light is reflected. Some is lost, but some can be re-reflected by the polished end surface of the connector back into the detector , the amount dependent on the type of connector and the quality of its polished surface. And although detectors have an antireflection coating, some light is reflected from the detector surface, which can be re-reflected from the window, connector, etc. Finally, the cleanliness of the optical surfaces involved can cause absorption and scattering. The sum total of these potential errors will be dependent on the connector type, wavelength, fiber size and NA.

Beyond the coupling errors, one has errors associated with the wavelength calibration. Semiconductor detectors used in fiber optic instruments (and systems too) have a sensitivity that is wavelength dependent. Since the actual source wavelength is rarely known, there is an error associated with the spectral sensitivity of the detector. By industry convention, the three cardinal wavelengths (850, 1300 and 1550 nm) are used for all power measurements, not the exact source wavelength. The source has a finite spectral width, very narrow for lasers, quite broad for a LED. In order to accurately measure the power of the source, one needs to know the spectral power distribution of the actual source being measured, the sensitivity of the detector and perform a complicated integration of the two...When one considers why FO power is measured (determining source output or receiver power to determine if a system in within margin or measuring loss), the impact of errors becomes apparent. But without knowing the system source spectral output, system detector spectral sensitivity and the spectral attenuation characteristics of the fiber, one cannot accurately predict system performance anyway.

Fiber optic components are sensitive to physical stress which can induce loss. One can see the effects of physical movement of fiber optic cables and connectors on fiber optic assemblies. A simple bend in singlemode fiber cable can induce several dB loss. All connectors are very sensitive to forces acting on the cable as it exits the backshell. Just handling fibers to make measurements can cause readings to vary by several tenths of dB.

NetCracker: A Network Design Dynamo
... black, twisted pair is blue, fiber optic is yellow, multicable wire is ... on designated
bandwidths. To locate stress points within the network, I set ...
After I set up a few simple network layouts, running the simulation was reminiscent of running an actual network. The packets flowed at varying rates over the different segments depending on designated bandwidths. To locate stress points within the network, I set up utilization bars next to the switches and routers, which displayed current utilization of the devices. I had the option to add other statistics, such as packets dropped and workload, to the devices' visual statistics.

Fiber-optic Networks Enable Innovative Strategies
... an intrinsic tensile stress of up to 600 ... service offerings. Regional fiber-optic networks
typically are ... transmission drop-off points (the POPs) typically ...
The technical direction a utility chooses for its communications network will reflect its operating and business aspirations. In general, the more complex and demanding the requirements, the more likely it is a fiber-optic network will best serve its needs (Table 1). Fiber-optic networks offer high capacity, a feasible technical solution for leasing excess capacity, reliable performance, low cost, ease of deployment, rapid upgradeability and a versatile range of network configurations.

A central requirement for communications media is operating reliability--one of optical fiber's key advantages. Optical fiber's dielectric nature makes it unaffected by electrical interference and therefore ideal for routing along existing powerline rights-of-way (ROW). Fiber-optic transmissions have few errors and low noise, are very secure from interception and are not susceptible to ill effects from weather conditions. Optical fiber is an extremely strong material. It is made from ultra-pure silica glass, which is nearly 200,000 times more pure than ordinary window glass. Optical fiber can withstand an intrinsic tensile stress of up to 600,000 pounds per square inch.

The reliability of optical fiber has been seen in extensive and long-standing use in the telecommunications industry. The earliest installations have been in operation since utilities began using fiber in the late 1970s for internal communications. Because of the inherent security of the power grid, fiber-optic cable deployment using the aerial power utility transmission ROW has gained a well-deserved reputation for reliability.

Fiber-optic networks often are cost-competitive with other options on the basis of initial installation and operation. The low cost of incremental capacity upgrades with optical networks means an initial installation has the potential to yield escalating savings and added revenues in future years with relatively low additional investment. Utilizing even a small portion of the potential transmission capacity of a fiber-optic network within the utility's traditional operations usually cost-justifies the network. A payback period of one to two years is not unusual and can be further shortened if some initially unused dark fibers are leased to third parties. In fact, partners may underwrite the initial system cost in return for access to ROW and easements for fiber-optic transmissions.
A utility's inherent advantage
Some utilities are choosing fiber-optic networks in order to implement a carrier's carrier strategy. Many of a utility's inherent benefits can make its network a superior solution for the establishment of new or extended telecommunications capability. Some of these include: Extensive ROW. The cost advantages of existing ROW and the quick deployment this allows make utilities attractive line-leasing partners for many communications carriers. Utilities have long acted as passive landlords by leasing pole attachments. Installing a fiber-optic network and leasing fibers rather than physical access allows for the creation of new revenue streams.
Reliability and security of the power grid. By installing aerial fiber-optic cable on transmission towers, a communications network can be accessed only by qualified personnel, making it invulnerable to dig-ups, the most common culprit behind telecommunications cable outages.
Existing infrastructure of utility substations and transmission and distribution lines. These lines are well positioned for the future deployment of fiber networks that run close to telecommunications end-user premises. Existing customer relationships with residences and businesses can provide the utility access and the ability to offer and bundle telecommunications services.
Qualified power utility personnel who are already qualified to work and place cables in the supply zone on a distribution pole.
Long, straight routes of the power transmission grid that are highly suitable for point-to-point telecommunications routes. The potential need for leased lines with high transmission rates is maximized at the area where the grid connects with populous areas.
The long-distance telecommunications market is expanding rapidly due to increased capacity demand and the addition of extensive redundancy circuits. This area also is growing because of the establishment of networks intended for resale to third-party wholesalers and retailers of long-distance services, and because the Regional Bell Operating Cos. now also are entering the long-distance market with their own competing facilities. Long-distance carriers, or interexchange carriers, operate the routes that connect the points of presence (POP) of different Local Access and Transport Areas (LATAs). These LATAs, which typically follow the boundaries of major metropolitan areas, may gradually change as the Telecommunications Act of 1996 takes effect. However, such changes will not affect the need for long-distance, point-to-point routes. The routes or networks have fairly simple topologies. Essentially they are point-to-point fiber-optic links between POPs in physically separate configurations that create enormous redundant loops. For example, routes that ultimately connect St. Louis with Sacramento might run via Denver and Salt Lake City, as well as Phoenix and Los Angeles.

Communications Engineering & Design - inDepth; September 2001: ...
... s looking glass, the sectors ... OMM’s transition to smaller ... to interconnect between high-volume
peering ... silica core fiber cable system ... Kasim points out ... and low cost ...

High Performance Fiber Optic Adhesives New high performance ...
... in novel ways, Dymax fiber optic adhesives offer ... Stress in Bonded Optics. ... 0.1% or
less Low to high glass transition points (T g ) A ...

New high performance adhesives minimize movement of parts on cure and during thermal excursions. By combining new ingredients in novel ways, Dymax fiber optic adhesives offer improved durability and reliability along with superior optical transmission, low outgassing and complete cure in seconds.

Download the technical papers:
Movement Between Bonded Optics
Stress in Bonded Optics

Low to no movement during cure and thermal excursions
(from -50°C to 200°C)
Exceptionally low shrinkage to 0.1% or less
Low to high glass transition points (Tg)
A range of refractive indices from 1.40-1.58
Low outgassing to 10-6 grams/gram
Superior optical transmission
Lower stress on bonded parts regardless of Tg

Plastic Fiber Optics for Lighting - Fiber Optic Lighting Products
... is hydroscopic. Optics ends must ... Aperture: 0.65; Glass Transition Temp: 53.8 ... lighting
system, low in ... core being high-purity ... 6 points of fiber per ...

Introduction - IR Fiber Review
... or softening points, and greater ... lensing and low laser induced ... For these high index
fibers ... common IR fiber optics: ZBLAN ... Glass transition or ...
Infrared (IR) optical fibers may be defined as fiber optics transmitting radiation with wavelengths greater than approximately 2 µm. The first IR fibers were fabricated in the mid-1960's from chalcogenide glasses such as arsenic trisulfide with losses in excess of 10 dB/m.1

IR fiber optics may logically be divided into three broad categories: glass, crystalline, and hollow waveguides. These categories may be further subdivided based on either the fiber material or structure or both as shown in Table 1. Over the past 25 years many novel IR fibers have been made in an effort to fabricate a fiber optic with properties as close to silica as possible, but only a relatively small number have survived. A good source of general information on these various IR fiber types may be found in the literature. 3,4,5,6 In this review only the best, most viable and, in most cases, commercially available IR fibers are discussed. In general, both the optical and mechanical properties of IR fibers remain inferior to silica fibers and, therefore, the use of IR fibers is still limited primarily to non-telecommunication, short-haul applications requiring only tens of meters of fiber rather than kilometer lengths common to telecommunication applications. The short-haul nature of IR fibers results from the fact that most IR fibers have losses in the few dB/m range. An exception is fluoride glass fibers which can have losses as low as a few dB/km. In addition, IR fibers are much weaker than silica fiber and, therefore, more fragile. These deleterious features have slowed the acceptance of IR fibers and restricted their use today to applications in chemical sensing, thermometry, and laser power delivery.

Main Subcategory Examples
Glass Heavymetal fluoride - HMFG ZBLAN - (ZrFM4-BaF2-LaF3-AlF3-NaF)
Germanate GeO2-PbO
Chalcogenide As2S3 and AsGeTeSe
Crystal Polycrystalline - PC AgBrCl
Single crystal - SC Sapphire
Hollow waveguide Metal/dielectric film Hollow glass waveguide
Refractive index < 1 Hollow sapphire at 10.6 µm Property Glass Crystal Hollow
Silica HMFG
ZBLAN Chalcogenide
Sapphire Hollow Glass Waveguide
Glass transition or melting point, oC 1175 265 245 412 2030 150
(usable T)
Thermal conductivity, W/m oC 1.38 0.628 0.2 1.1 36 1.38
Thermal expansion coefficient, 10-6 oC-1 0.55 17.2 15 30 5 0.55
Young's modulus, GPa 70.0 58.3 21.5 0.14 430 70.0
Density, g/cm3 2.20 4.33 4.88 6.39 3.97 2.20
Refractive index
(l,µm) 1.455
(0.70) 1.499
(0.589) 2.9
(10.6) 2.2
(10.6) 1.71
(3.0) NA
dn/dt, 10-5 oC-1
(l, µm) +1.2
(1.06) -1.5
(1.06) +10
<10.6) -1.5
(10.6) +1.4
(1.06) NA
Fiber transmission range, µm 0.24-2.0 0.25-4.0 4-11 3-16 0.5-3.1 0.9-25
Loss at 2.94 µm, dB/m ~800 0.08 5 3 0.4 0.5
Loss at 10.6 µm, dB/m NA NA 2 0.5 NA 0.4

... Fiber Optics: The technology ... Glass transition temperature (Tg ... arrangement of points
in a ... at a high temperature. ... temperature a glass can ... at low temperatures ...

Glass transition temperature (Tg): Temperature at which a glass changes from a supercooled liquid into a solid.

    Reference: http://www.cedmagazine.com/ced/2001/0901/id4.htm
Deb Phillips
PRO pts in pair: 77
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