Carlson Wireless USA revision 1.05 Page 6
SYSTEM PLANNING
Certain requirements are necessary for the i-WLL-15 system to function.
(1) A radio path with losses fitting within the capacity of the system
.
We have a chart showing various antenna and distance combinations
.
What’s an acceptable “Link Margin“? An accepted theory is that 10 dB of
fade margin will deliver a 90% reliability and 20 dB will deliver a 99% reliability
etc.. There are other factors that affect this including vertical or horizontal po-
larization. At 2.4 GHz there is only a small ground wave component involved
in the radio propagation. This means that the above numbers are presuming
clear LOS (line of sight). Multi-path occurs when a reflector such as earth’s
terrain or man made structures cause additional delayed signals to be re-
ceived. If a signal was delayed 180 degrees out of phase with the line of sight
signal, and the magnitudes are the same, they will cancel out completely! In
the real world, if you do have line of sight path, multi-path degradation is the
reason why you need a minimum of 6 to 10 dB of margin. If you don’t have
line of sight, multi-path could easily cause 20 dB of degradation.
Distance Distance
Model
Path Loss
ERP
Link Margin
in Miles
in km
in dB
in dBm
1.5
2.4
I-WLL-15
108
27
27
2.0
3.2
I-WLL-15
110
27
25
5.0
8.0
I-WLL-15
118
27
17
7.0
11.3
I-WLL-15
121
27
14
8.0
12.9
I-WLL-15
122
27
13
8.0
12.9
I-WLL-25
122
29
17
10.0
16.1
I-WLL-15
124
27
11
10.0
16.1
I-WLL-25
124
29
15
12.0
19.3
I-WLL-25
126
29
13
15.0
24.1
I-WLL-25
128
29
11
20.0
32.2
I-WLL-35
130
36
24
25.0
40.2
I-WLL-35
132
36
22
50.0
80.5
I-WLL-35
138
36
16
Fade Margin Chart
Carlson Wireless USA revision 1.05 Page 15
PARTS LIST i-WLL-15
PART-REV # DESCRIPTION
19 – L PCB, LINE INTERFACE & POWER REGULATOR
18 – S PCB, DIGITAL TOP
17 – B MOUNT, FRONT ANTENNA
16 – (RESERVED)
15 – (RESERVED)
14 – G U-BOLT, 2-3/4 INCH
13 – E CLAMP BASE, 2 3/4 INCH
12 – B U-BOLT, 4-1/2 INCH
11 – C END CAP, FRONT
10 – (RESERVED)
09 – A RING, RETAINING
08 – G BRACKET, SADDLE
07 – G PLATE, MOUNTING
06 – B GRIP, CABLE & SEALING GLAND
05 – C O-RING 1/8 x 3.50 x 3.75
04 – B ANTENNA, 16 ELEMENT 13.5 dB GAIN
03 – D SHIELD, INNER SS
02 – D HOUSING, OUTER
01 – E END CAP, REAR
