Richard-Allan Scientific: Followup Site Survey
Friday, January 30th
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Richard-Allan Scientific: Followup Site Survey Friday, January 30th |
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| This graph details the area that was surveyed. It includes the floor plan and the dimensions of the building. It can be useful to refer back to this view from some of the other graphs to help orient yourself. |
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| This Coverage Area Plot details the 802.11 channels that were discovered while performing the site survey. The survey area is split into regions where each region consists of data points collected while communicating over the same channel and with the same access point. Each colored ring represents a different channel/access point combination. |
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| This Coverage Area Plot details the 802.11 data rates that were observed while performing the site survey. The survey area is split into regions where each region consists of data points collected while communicating at the same maximum data rate and with the same access point. Each colored ring represents a different data rate/access point combination. In this case, all transmissions occured at the maximum 802.11b data rate. |
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| This 2D Contour Graph represents the Signal-to-Noise Ratio (SNR) for the entire survey area. A contour graph plots the same color at every location that has the same value. In this case, every location that has a similar SNR is represented using the same color. You can quickly see areas with weak, medium, and strong coverage by focusing only on the main color. In this graph, Red indicates a weak SNR, Green indicates a medium or acceptable SNR, and Blue indicates a strong SNR. Shades of each of these colors provide more detail on the SNR values. Each band of a shaded color represents a fairly small range of SNR values. |
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| This 2D Contour Line Graph represents the Signal-to-Noise Ratio (SNR) for the entire survey area. A contour line graph draws lines that band together locations with similar values. Lines are drawn to separate small ranges of values. This produces a topological map that shows the SNR ranges for the entire survey area. |
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The above two graphs highlight the areas that were either improved or made worse between the intial site survey and the survey that occurred after some adjustments were made. The highlighting is done by exaggerating the high SNR values and the low SNR values and shrinking the middle (green) portion. Compare this to the next graph which has the color boundaries set to the exact same values. So, red areas in each graph indicate the same SNR values as do blue and green areas. Note that red areas do not necessarily mean poor signal coverage and blue areas don't necessarily mean strong coverage. Other included contour graphs show unacceptable or strong coverage areas. This one merely highlights the changes. The biggest difference between the before and after are noticed in the center of the area--in the main warehouse. The south half of the warehouse has fairly poor coverage now, especially compared to the previous survey. I'm fairly certain this has to do with the new location of the antenna in the warehouse. It was placed just north of a large, metal ventilation unit. This was done to protect the antenna from damage from forklifts, but the large amount of sheet metal blocks a large portion of the signal to the south end of the warehouse. However, coverage was improved on the northern half of the main warehouse. It appears that a similar affect occurred in the southeast warehouse. The antenna was lowered to prevent some bleeding of the signal out of the building. Again, to protect the antenna from damage, the antenna was mounted on the east side of a metal support beam. This location blocks a large amount of the signal from covering the west end of the warehouse. Coverage was improved in the Northeast Warehouse in the furthest most northeast corner by the relocation of an antenna into that room. The coverage in this room is now very good everywhere except the very northeast corner. The west side has SNRs in the 20's which should be acceptable even though it shows up as red in the graph. Previously, the west side had SNR values below 20. In the offices area, coverage remained similar between the two site surveys except for the boundary between the access points where it decreased. Since the antennas in the southwest corner where replaced by lower gain antennas to reduce the bleed of the signal outside of the building, this seems expected. The good news is that the new antennas still adequately cover the office area. |
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This 3D Contour Graph works with the same principals as the 2D Contour Graphs except that the color bands are given height as well as just different colors. The grid lines, shading, and colors all combined to give depth to the plot. Strong areas of coverage appear as tall mountains and weak areas appear as deep valleys. This type of graph is most visually effective when viewed interactively on the computer, but it can still easily and dramaticly reveal coverage issues when included in static reports. |
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The Stretched Survey Trail graph is a way of plotting three-dimensional data (X and Y location and the signal value) on a two-dimensional graph. To do this, the two location dimensions are taken away and replaced with a single dimension. The one location dimension is a count of the strides taken while collecting the survey data. This is plotted along the X-axis of the graph. The other dimension, plotted along the Y-axis, is the collected value of interest. This graph plots the number of TCP/IP receive errors received at each location. At most locations, no receive errors were experienced. But at around the 700th stride, a large number of receive errors occurred. If you were to zoom in on the spike that occurs near the 700th stride, you would learn that the receive errors occurred during two different visits to the location at (-56, -108). You can then look that location up on the area coverage map. |
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This graph represents a vertical cross section of the survey area. Any data collected within the ten-foot wide cross section is plotted on the graph. The left most part of the graph represents the south most part of the building and the right most side represents the north most part of the building. From this graph, you can see the deep valley that occurs about 20 feet south of the center of the building and another large decline that occurs when transitioning from the Main Warehouse to the Northeast Warehouse. |
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-181 - -144ft |
-144 - -107ft |
-107 - -70ft |
-70 - -33ft |
-33 - 4ft |
4 - 41ft |
41 - 78ft |
78 - 115ft |
115 - 152ft |
152 - 189ft |
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210 - 173ft |
Data Points | 0 | 25 | 92 | 127 | 145 | 42 | 64 | 50 | 68 | 29 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
17.7
σ=1.95 |
28.6
σ=10.05 |
38.4
σ=1.84 |
23.0
σ=8.28 |
21.9
σ=4.78 |
20.6
σ=3.71 |
25.6
σ=3.29 |
20.6
σ=5.30 |
15.4
σ=1.30 |
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173 - 136ft |
Data Points | 0 | 24 | 85 | 74 | 81 | 45 | 37 | 47 | 42 | 21 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
37.0
σ=12.25 |
43.7
σ=5.15 |
42.2
σ=2.12 |
29.0
σ=7.51 |
25.3
σ=4.41 |
24.8
σ=1.66 |
33.6
σ=3.41 |
25.6
σ=4.27 |
20.3
σ=1.39 |
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136 - 99ft |
Data Points | 0 | 56 | 101 | 58 | 93 | 58 | 48 | 48 | 26 | 48 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
43.4
σ=1.97 |
41.8
σ=10.70 |
41.5
σ=5.30 |
31.2
σ=6.87 |
30.6
σ=4.17 |
28.4
σ=3.49 |
32.7
σ=6.23 |
24.9
σ=4.54 |
20.2
σ=2.43 |
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99 - 62ft |
Data Points | 0 | 11 | 31 | 49 | 105 | 76 | 57 | 49 | 63 | 84 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
42.3
σ=2.20 |
15.4
σ=1.23 |
22.0
σ=9.59 |
26.8
σ=8.70 |
41.4
σ=4.07 |
36.9
σ=9.00 |
32.8
σ=8.13 |
27.1
σ=7.74 |
28.5
σ=9.70 |
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62 - 25ft |
Data Points | 0 | 0 | 0 | 110 | 141 | 91 | 52 | 39 | 37 | 66 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
22.5
σ=2.38 |
35.3
σ=6.31 |
36.2
σ=3.82 |
36.4
σ=4.77 |
33.8
σ=2.67 |
30.6
σ=4.11 |
28.0
σ=3.43 |
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25 - -12ft |
Data Points | 0 | 0 | 23 | 20 | 69 | 27 | 44 | 31 | 46 | 16 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
0.0
σ=0.00 |
18.7
σ=1.40 |
19.4
σ=0.99 |
22.8
σ=5.96 |
23.4
σ=4.92 |
28.0
σ=2.95 |
29.7
σ=5.08 |
26.0
σ=4.76 |
28.1
σ=2.02 |
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-12 - -49ft |
Data Points | 0 | 0 | 0 | 0 | 69 | 49 | 57 | 42 | 48 | 34 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
22.9
σ=3.78 |
21.0
σ=4.33 |
21.2
σ=4.68 |
22.0
σ=6.42 |
25.0
σ=1.99 |
24.9
σ=1.96 |
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-49 - -86ft |
Data Points | 0 | 60 | 126 | 181 | 116 | 203 | 157 | 95 | 70 | 68 | ||
| Signal to Noise Ratio |
0.0
σ=0.00 |
31.6
σ=2.06 |
33.6
σ=1.88 |
39.4
σ=2.47 |
44.2
σ=3.00 |
43.1
σ=3.55 |
37.5
σ=2.33 |
30.8
σ=3.35 |
23.1
σ=2.85 |
19.8
σ=2.71 |
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-86 - -123ft |
Data Points | 141 | 148 | 190 | 182 | 214 | 224 | 133 | 162 | 142 | 76 | ||
| Signal to Noise Ratio |
37.9
σ=2.97 |
32.9
σ=9.64 |
24.0
σ=8.00 |
34.8
σ=10.35 |
46.0
σ=2.52 |
48.5
σ=5.20 |
40.9
σ=2.86 |
33.9
σ=2.64 |
26.9
σ=4.45 |
22.0
σ=2.06 |
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-123 - -160ft |
Data Points | 195 | 211 | 191 | 209 | 93 | 138 | 101 | 106 | 85 | 0 | ||
| Signal to Noise Ratio |
41.6
σ=3.60 |
45.4
σ=7.72 |
31.8
σ=8.40 |
27.1
σ=8.13 |
43.8
σ=1.49 |
45.6
σ=2.27 |
39.4
σ=2.87 |
33.9
σ=2.57 |
26.3
σ=4.12 |
0.0
σ=0.00 |
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-160 - -197ft |
Data Points | 239 | 271 | 138 | 65 | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Signal to Noise Ratio |
39.8
σ=4.63 |
45.4
σ=6.02 |
37.5
σ=4.25 |
28.4
σ=3.50 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
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-197 - -234ft |
Data Points | 27 | 47 | 6 | 8 | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Signal to Noise Ratio |
34.3
σ=2.72 |
37.8
σ=2.01 |
34.3
σ=2.16 |
24.9
σ=1.89 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
0.0
σ=0.00 |
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