TRACER 4106/4206 System Manual | Section 2 Microwave Path Engineering Basics |
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1.LINE-OF-SIGHT
The TRACER 4106 and 4206 systems are designed for operation in the
Terminology
Wireless communication from a single site to another individual site. Contrast with
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
x |
| = 10 ⋅ log |
| | x | | (dBm) |
dBm | 10 | |
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| 1mW |
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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) |
© 2004 ADTRAN, Inc. | 15 |