ADTRAN 4206 Plan A, 4106 Plan A Line-Of-Sight, Terminology, Decibels, Calculating the Fade Margin

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TRACER 4106/4206 System Manual

Section 2 Microwave Path Engineering Basics

 

 

1.LINE-OF-SIGHT

The TRACER 4106 and 4206 systems are designed for operation in the license-free 2.400 to 2.4835 GHz and 5.725 GHz to 5.850 GHz industrial, scientific and medical (ISM) bands, respectively. Radio wave propagation in these bands exhibit microwave characteristics which are ideally suited for point-to-point, line-of-sight communications. Line-of-Sight requires that the transmitting antenna and receiving antenna are able to “see” each other, and that the straight-line path between the two antennas is free of obstructions, such as buildings, trees, mountains, and, in longer paths, even the curvature of the earth. In addition, for maximum signal strength the area around the visual line-of-sight where microwave signals reflect (Fresnel zone) must also be free of obstructions. Fresnel zones are discussed in more detail on page 22.

Terminology

Point-to-Point

Line-of-Sight

Wireless communication from a single site to another individual site. Contrast with point-to-multipoint.

An unobstructed, direct path exists between the transmitting and the receiving antennas.

2.DECIBELS

Understanding the decibel (dB) format is key when discussing microwave path engineering because the received signal power is often expressed in decibel format. In general, any quantity can be expressed in decibels. If the quantity x is a power level (in Watts), the decibel equivalent is defined as

xdB = 10 log10(x)

(dB)

If the quantity x is referenced to a milliwatt (mW), then the decibel-milliwatt (dBm) is used instead of a generic decibel.

x

 

= 10 log

 

x

(dBm)

dBm

10

------------

 

 

 

1mW

 

Using the decibel format simplifies power calculations by reducing multiplication and division operations into addition and subtraction operations.

3.CALCULATING THE FADE MARGIN

It is imperative to determine if the proposed microwave path is suitable (at a minimum) for ideal, nondistorted signals before attempting installation.

The fade margin (F ) is a value in decibels (dB) that represents the amount of signal reduction that can be tolerated before the link exceeds the specified bit error rate (BER). Fade margin is simply the difference between the available signal power at the receiver (PR ) and the receiver sensitivity (Psens ).

F = PR Psens = PT + GT + GR - L - LP - Psens

(dB)

612804206L2-1A

© 2004 ADTRAN, Inc.

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Contents Tracer 4106/4206 Trademarks To the Holder of the ManualAbout this Manual Revision History Save These Important Safety Instructions Safety InstructionsRadio Frequency Interface Statement FCC-Required InformationExposure to Radio Frequency Fields FCC Output Power RestrictionsPre-Sales Inquiries and Applications Support Repair and ReturnInstallation and Maintenance Support Post-Sale SupportTraining Table of Contents Table of Contents Tracer 4106/4206 System Manual System Description Operational Features and BenefitsConfiguration and Management System OverviewOther Considerations Receiver PowerLine-of-Sight Receiver Sensitivity Antenna InformationADTRAN, Inc Calculating the Fade Margin LINE-OF-SIGHTTerminology DecibelsReceiver Power Antenna Gain Transmitted Power PTCarrier Wavelength λ Path Distance dSystem Losses L Typical Coaxial Loss for Common Cable Types Path Loss LPT1 Ports Receiver SensitivityAntenna Beam Patterns Antenna InformationAntenna Alignment Tracer Rssi Test PointsFresnel Zones, Earth Curvature, & Antenna Heights Other Considerations Path AvailabilityTerrain Terrain Factor Description Climate Climate Factor Description Values normally used are listed belowReviewing the Front Panel Design At-A-Glance SpecificationsRssi Monitoring Interface Equipment DimensionsPower Requirements Reviewing the Front Panel DesignReviewing the Tracer 4106/4206 Rear Panel Design RS-232 Connection Pinout Name Connector DescriptionRS-232 Connection DB-25 Terminal Use Rear Panel DescriptionTracer 4106/4206 DCE to Terminal DTE Diagram DB-25 RS-232 Connection Modem UseTracer 4106/4206 DCE to Personal Computer DB-9 T1 Interface Connector Pinout T1 Connections RJ-48CTracer 4106/4206 DCE to Modem DCE DB-25 Fuse Alarm Contacts Plug-In Terminal BlockDC Power Connection Plug-In Terminal Block Antenna Interface N-Type connectorHardware Description Specification Transmitter AT-A-GLANCE SpecificationsVT100 Terminal Interface Engineering Guidelines Tracer 4106/4206 System Manual Unpack and Inspect the System Network Turnup ProcedureUnpack and Inspect the System Contents of Adtran ShipmentIntroduction Tools RequiredChannel Selection Customer ProvidesGrounding Instructions Supplying Power to the Unit Mounting OptionsInstructions for Rackmounting the Tracer 4106/4206 Inch Rackmount Illustration Connecting the T1 InterfaceMenu Descriptions User Interface GuideTerminal Menu Window Navigating the Terminal MenuTo do this Press this key Navigating using the Keyboard KeysPassword Protection Terminal Menu and System ControlRF Status Menu DescriptionsElapsed Time Contact InformationRemote Tracer Status T1 Status Error/Alarm OnlyRx Power Tx PowerMain Menu Tracer System Options Tracer System Options RF Bandplan Receiver Sensitivity Active Bandwidth Receiver Sensitivity for the Tracer 4106/4206Resets all system error counters for the Tracer 4106/4206 T1 Interface Alarms T1x Status/Configuration/LoopbackT1X STATUS/CONFIGURATION/LOOPBACK T1X Line Build OUT T1 Remote Link Loopback T1X Performance History Overview Installing/Troubleshooting the Tracer HardwareRF Down LED LED Indicators PWR LEDOverview TST LEDRF LOW LED T1 Interface Alarm LEDsSTEP-BY-STEP Troubleshooting RF ErrorsINSTALLING/TROUBLESHOOTING the Tracer Hardware Installing/Configuring T1 Hardware