ANUE Network Emulators are an essential tool forsatellite communications testing providing vari-

able path delays, jitter simulation, and dynamic errorintroduction, acting just like in a real satellite networklink. High-bandwidth satellite networks provide a grow-ing variety of network services. Before these servicescan be deployed they must be thoroughly tested on theground. Since satellites are frequently in orbits that aregreat distances apart, it is essential to emulate those dis-tances while testing on the ground.

Round-trip transmission times to and from geo-synchronous orbit – where satellites park some22,300 miles above the equator – are approximately250 msec, a long time for a communications network!The satellites’ position is not constant and, in fact,because they communicate with both ground stationsand other satellites, there will be transmission paths ofmany different distances to consider. Unlike a fixedlength of fiber optic cable, the Network Emulator is likea variable-distance cable without dB loss, so it can beused for all-distances testing rather than specific-distance testing.

Using Anue Nework Emulators to simulate satellite links

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Test Solution #301

Satellite CommunicationsSatellite Communications

The communication satellite is a moving object with acontinuously-varying distance to what it communicateswith. A Doppler effect simulation feature requested byAnue customers emulates the variations in distance witha continuous smooth slew of delay distance.

One of the Doppler effects is receiver signal jitter. Areceiver expects a pulse of data at very regular intervals.The receiver’s eye pattern determines which signals itfinds acceptable. Should the edge of a signal change at atime inside the eye pattern the receiver may go out of syn-chronization and communication might be temporarilylost. As the transmitter receiver pair move relative toeach other the regular intervals may not be regularenough. The Network Emulator forces the jitter to seehow the receiver and in fact the application reacts.

The impact on applications of long delays, jitter,Doppler effects, and other impairments, can be criticaland must be tested before any satellite-based communi-cation system is launched. After launch may be too late,that is why an Network Emulator is essential tothe satellite communications lab.

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Satellite services previously reserved for largebusinesses are becoming more available to smaller

enterprises with more consumers using servicesincluding telecommunications and TV distribution. Adirect-to-the-consumer architecture is used in directbroadcast systems, mobile communications satellitesystems, and now even in broadband, high data rate

multimedia satellite products and services.Applications such as collaborative computing,

distributed CAD/CAM, scientific visualization, remotesensing data relay, messaging and navigational

services, electronic publishing, and others, createdemand for new satellite telecommunications

networks. The effects of dynamic variation of datapath length and related jitter must be considered andtested for with each new application to assure it will

work before release to consumers.

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Applications

Satellite link emulation applications include the designing,building, and test of:

Free-space optics (FSO) – A line-of-sight technologythat uses lasers to provide optical bandwidth connec-tions that can send and receive voice, video, and datainformation on invisible beams of light.

Defense – Satellite communications is the backbone ofthe military’s missile defense system as well as itsworldwide communication system.

“Internet in the Sky” – Using satellite links in high-capacity network-centric global communications sys-tems.

Global Area Networking – Extending broadband ser-vices, multimedia, storage, transaction processing, ande-commerce applications to remote locations.

Private and public satellite-to-ground or satellite-to-satellite communications networks.

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Specifications

Specifications of Network Emulators for testing satel-lite link transmissions:

Doppler shift emulation

Automatically increase and/or decrease the delaytime in increments as small as one part per million(ppm) to simulate the movement of satellites in rela-tion to one another and Earth stations.

Multiple-protocol support at real-time full-line data ratesup to 10.7 Gbps, all frame sizes

SONET/SDH

OC3 @ 155 MbpsOC12 @ 622 MbpsOC48 @ 2.488 GbpsOC192 @ 9.953 Gbps

10/100 Ethernet

Gigabit Ethernet @ 1.25 Gbps

10 Gigabit Ethernet

9.953.28 Gbps WAN Phy10.3125 Gbps LAN Phy

Fibre Channel

1.0625 Gbps2.125 Gbps4.25 Gbps10 Gbps

10G FEC data rates up to 10.709 Gbps

Increase maximum delay path length with the delaydoubler, tripler, and quadrupler as shown below:

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Distances Rate 1x 2x 3x 4x

50,000 km 31,000 mi 2.5 Gbps 250 msec 500 msec 750 msec 1 sec

300,000 km 186,000 mi 1 Gbps 1.5 sec 3 sec 4.5 sec 6 sec

200,000 km 124,000 mi 10 Gbps 1 sec 2 sec 3 sec 4 sec

051012

Contact us for other protocols, data rates, and custom applica-tion requirements.

Specifications subject to change without notice.