Quatech, Inc. | Airborne Enterprise Module Databook |
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Link Margin provides a measure of all the parts of the RF path that impact the ability of two systems to communicate. The basic equation looks like this:
| EIRP (dB) = TxP + TxA – TxC |
| Link Margin (dB) = EIRP – FPL + (RxS + RxA – RxC) |
Where: | TxP = Transmitter output power (dBm) |
| TxA = Transmitter antenna gain (dBi) |
| TxC = Transmitter to Antenna coax cable loss (dB) |
| FPL = Free Path Loss (dB) |
| RxS = Receiver receive sensitivity (dBm) |
| RxA = Receiver antenna gain (dBi) |
| RxC = Receiver to Antenna coax cable loss (dB) |
This is a complex subject and requires more information than is presented here, Quatech recommends at reviewing the subject and evaluating any system at a basic level.
It is then possible, with a combination of the above items and an understanding of the application demands, to achieve a link quality optimized for the application and host design. It is important to note that this is established with a combination of hardware selection, design choices and configuration of the radio.
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