Site Survey Tool - TamoGraph

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System Requirements
Driver Installation
Licensing and Trial Version Limitations
Interface Overview
Access Point List
Floor Plan / Site Map
Plans and Surveys, Properties, and Options Panel
Main Menu
Performing a Site Survey
New Project Wizard
Data Collection
Understanding Survey Types: Passive, Active, and Predictive
Active Survey Configuration
Best Practices, Tips, and Tricks
Survey Job Splitting
Predictive Surveys
Drawing Walls and Other Obstructions
Drawing Attenuation Zones
Placing and Configuring Virtual APs
Working with Presets
Applying Visualizations
Working with Multi-floor Sites
Mixing Real and Virtual Data
Best Practices, Tips, and Tricks
Analyzing Data – Passive and Predictive Surveys
Selecting Data for Analysis
Adjusting AP Locations After Passive Surveys
Splitting an AP into Multiple Unique APs
Working with Multi-SSID APs
Visualization Types
Signal Level
Signal-to-Noise Ratio
Signal-to-Interference Ratio
AP Coverage Areas
Number of APs
Expected PHY Rate
Frame Format
Channel Bandwidth
Channel Map
Analyzing Data – Active Surveys
Selecting Data for Analysis
Visualization Types
Actual PHY Rate
TCP Upstream and Downstream Rate
UDP Upstream and Downstream Rate
UDP Upstream and Downstream Loss
Round-trip Time
Associated AP
Spectrum Analysis
Hardware Requirements
Spectrum Data Graphs
Performing Spectrum Analysis Surveys
Viewing Collected Spectrum Data
Exporting Spectrum Data
Reporting and Printing
Customizing Reports
Google Earth Integration
Configuring TamoGraph
Plans and Surveys
Plan / Map
Client Capabilities
Colors and Value Ranges
AP Detection and Placement
Visualization Settings
Configuring GPS Receiver
Using GPS Configuration Dialog
Finding the GPS Receiver Port Number
Taking Photographs
Voice Control
Using TamoGraph in a Virtual Machine
Frequently Asked Questions
Sales and Support

Signal-to-Noise Ratio

This visualization shows the signal-to-noise ratio (SNR) measured in dB. SNR is a measure to quantify by how much the signal level exceeds the noise level. Noise is generated by non-802.11 sources of radio waves (this includes 802.11 frames damaged during propagation). In low SNR zones, client devices may not be able to communicate with APs. SNR is shown for the AP that has the strongest signal in the given map area among the APs selected for analysis. You can deselect one or several of the selected APs to see SNR values for less strong APs.

In a typical environment, the noise level is about -90 dBm. The signal level measured within a few meters from the AP would be about -50 dBm. This gives an SNR value of 40 dB, which is considered excellent. Marginal connectivity is possible when the AP signal level is -85 dBm, so an SNR value of 5 dB is considered poor. A higher noise level and, correspondingly, a lower SNR are usually caused by Bluetooth devices, cordless phones, and microwave ovens.

Double-clicking on the SNR legend on the status bar allows you to configure the color scheme and change its value range.

Suggested Solutions

When low SNR areas are discovered, two possible strategies should be considered: increasing the signal level or decreasing the noise level. The first strategy is discussed in the previous chapter; to decrease the noise level, the following solutions are suggested:

· Check the environment for potential sources of noise and turn them off, if possible, to see how that affects SNR.
· If you experience low SNR values in the 2.4 GHz band, consider switching your APs to the 5 GHz band, where noise level is typically lower.
· If switching to the 5 GHz band is not an option, try to select a different channel in the 2.4 GHz band.

Note that identifying and removing the source of noise might not be an easy task. In practice, the easiest solution is usually increasing the signal level rather than decreasing the noise level.