Measuring Signal Performance
Edge
TM
Multipoint and Quickbridge - Hardware Installation Guide 63
Procedure
1. Start with the transmit power and the number of the channel to be used in dBm. Subtract the total loss of all transmission
elements between the antenna and the radio on one side of the link (dB).
2. Add the gain of the antenna you will be using. The total is the EIRP (Equivalent Isotropically Radiated Power).
3. Determine the path loss of the microwave link by using the mathematical formula of L
p,
illustrated in Calculating Link
Budget.
4. Add the gain of the antenna on the second side of the link.
5. Subtract the total loss of all transmission elements between the antenna and the radio on the second side of the link. The
result is the Received Signal Level (RSL).
6. For details on the receive sensitivity and data rate values used for the wireless link, for details refer to Edge
TM
Hardware
Installation Guide.
7. Subtract this value from the Received Signal Level; this is the Fade Margin.
:
• The RSL must be higher than the Receiver Sensitivity plus the Fade Margin for a good link. The amount of Fade
Margin indicates the reliability of the link. The more the Fade Margin, the more reliable is the link.
The results of this link budget calculation are very important for determining any potential problems during installation. If you
have calculated the expected RSL, you can verify that it has been achieved during installation and troubleshooting.
Tabulated below is the relation between the Distance and Link Budget, for a selected frequency:
Reference Frequency: 5600 MHz Center Frequency for Europe
Link Budget
(dB)
Distance
(m)
Fresnel
Zone (m)
Link Budget
(dB)
Distance
(m)
Fresnel
Zone (m)
Link Budget
(dB)
Distance
(m)
Fresnel
Zone (m)
61 4.8 0.3 91 151 1.4 121 4.8 8.0
62 5.4 0.3 92 170 1.5 122 5.4 8.5
63 6.0 0.3 93 190 1.6 123 6.0 9.0
64 6.8 0.3 94 214 1.7 124 6.8 9.5
65 7.6 0.3 95 240 1.8 125 7.6 10.1
66 8.5 0.3 96 269 1.9 126 8.5 10.7
67 9.5 0.4 97 302 2.0 127 9.5 11.3
68 11 0.4 98 339 2.1 128 10.7 12.0
69 12 0.4 99 380 2.3 129 12.0 12.7
Link Budget
(dB)
Distance
(m)
Fresnel
Zone (m)
Link Budget
(dB)
Distance
(m)
Fresnel
Zone (m)
Link Budget
(dB)
Distance
(m)
Fresnel
Zone (m)
70 13 0.4 100 426 2.4 130 13.5 13.4
71 15 0.5 101 478 2.5 131 15.1 14.2
72 17 0.5 102 537 2.7 132 17.0 15.1
73 19 0.5 103 602 2.8 133 19.0 16.0
74 21 0.5 104 676 3.0 134 21.4 16.9
75 24 0.6 105 758 3.2 135 24.0 17.9
76 27 0.6 106 850 3.4 136 26.9 19.0
77 30 0.6 107 954 3.6 137 30.2 20.1
78 34 0.7 108 1071 3.8 138 33.9 21.3
79 38 0.7 109 1201 4.0 139 38.0 22.6
80 43 0.8 110 1348 4.2 140 42.6 23.9
81 48 0.8 111 1512 4.5 141 47.8 25.3
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