airFiber - Output Power Needed to Achieve Desired Modulation

Table of Contents


  1. Introduction
  2. Suggested Max TX Power
  3. Sensitivity

Introduction


Back to Top

In order to achieve certain modulation, enough signal strength is necessary to keep it stable. Radio sensitivity information is available in almost all our products' data sheets (downloadable at the bottom of each product page in www.ubnt.com). However, not all users know that the output power also determines what the maximum modulation rate is. Our airFiber 5X is a very powerful device and every dB matters in order to get maximum throughput and optimize efficiency.

For this reason we are sharing here two tables: one showing suggested maximum Tx Power and another showing radio sensitivity depending on channel width and modulation.


Suggested Max TX Power


Back to Top

NOTE:

Remember that maximum output power depends on country code and frequency.

Suggested Max TX Power:

 Modulation Output Power
8x 19-20 dBm
6x  21-22 dBm
4x  23-24 dBm
1-2x  26 dBm
1/4x 26 dBm

 

It means if you want to achieve up to 8x modulation it's highly recommended to use output power up to 20dBm, if you use higher levels, for example 21dBm output power you will be only able to get up to 6X.


Sensitivity 


Back to Top

Radio sensitivity depends on channel width and modulation, for example if you want to get 8X modulation using 30MHz channel you need a received signal strength of -62dBm or better (like -60dBm, -55dBm, etc...).

NOTE:

It's a good practice to keep a certain fade margin in case of weather changes or other situations that could temporarily affect your link. Recommended fade margin depends on your area and link distance. In most cases, it's recommended to keep at least 5dBm of fade margin.

 

BW (MHz) Rate RX Power (dBm)

50

8x

-60

50

6x

-67

50

4x

-74

50

2x

-81

50

1x

-83

 

 

 

40

8x

-61

40

6x

-68

40

4x

-75

40

2x

-82

40

1x

-84

 

 

 

30

8x

-62

30

6x

-69

30

4x

-76

30

2x

-83

30

1x

-85

 

 

 

20

8x

-64

20

6x

-71

20

4x

-78

20

2x

-85

20

1x

-87

 

 

 

10

8x

-66

10

6x

-74

10

4x

-81

10

2x

-88

10

1x

-90