Operating Manual

Chapter3 Installation 3
3. Installation
3.0 Overview
The n920T 2020 complies with FCC part 15 at the modular level for operation
in the license-free 902-928 MHz ISM band. This chapter provides guidelines
for installing and deploying equipment which incorporates the n920T 2020
module.
3.1 Estimating the Gain Margin
Successful communication between n920T 2020 modules is dependent on
three main factors:
 System Gain
 Path Loss
 Interference
System gain is a calculation in dB describing the performance to be expected
between a transmitter-receiver pair. The number can be calculated based on
knowledge of the equipment being deployed. The following four factors
make up a system gain calculation:
1. Transmitter power (user selectable)
2. Transmitter gain (transmitting antenna gain minus cabling loss between
the transmitting antenna and the n920T 2020 module)
3. Receiver gain (Receiving antenna gain minus cabling loss between the
receiving antenna and the module)
4. Receiver sensitivity (Specified as -108dBm on the n920T 2020 module)
In the following illustration, the transmitting antenna has a gain of 6 dB, and
the receiving antenna has a gain of 3 dB. The cable loss between the module
and the antenna is 2 dB on both the transmitting and receiving side.
Transmitter
30 dBm
Output Power
Receiver
Sensitivity =
-105 dBm
Cable Loss = 2 dBCable Loss = 2 dB
Antenna Gain = 6 dB
Antenna Gain = 3 dB