Example 4 - Mantracourt T24-BSi Technical Manual

Example 4

In this final example a T24-SA is fitted inside a Loadlink transmitting data to a T24-BS base station. The T24-SA
has an integral Rad24i radio and the Loadlink has been assembled with fibreglass RF windows for minimum signal
loss. The T24-BS contains a Rad24e radio that is connected to an antenna of 2.9dBi gain by a 3m length of RG174
cable; attenuation at 2.4GHz is 1.67dB/metre in this cable assembly. The arrangement is illustrated at Figure 3.
G = 1dB
T
Rad24i
Tx
Loadlink enclosure loss
= 0.2dB
G = Transmit antenna gain
T
G = Receive antenna gain
R
Sum of all the gains = G
Sum of all the losses = Enclosure loss + Path loss + Feeder loss
From the Path loss table we see that the loss over 150m is 75.92dB so the sum of losses is:
0.2 + 75.92 + 5.0 = 81.12
Subtract that from the sum of the gains: 3.9 – 81.12 = -77.22
So the estimated power at the receiver input is -77.22dBm
Refer to Table 1 below that shows the relationship between receiver input power and RSSI, an input level of -
77.22dBm will result in an RSSI between -80 and -85.
Mantracourt Electronics Limited T24 Technical Manual
Slant range = 150metres
G
Feeder loss = 5.0dB
Figure 3
+ G = 1 + 2.9 = 3.9
T R
= 2.9dB
R
3m of RG17 4
Rad24e
R
x
T24-BS
84