Data Collection

Once the project configuration has been completed, you are ready to perform the actual survey by walking the site with a laptop that runs TamoGraph (unless you perform predictive modeling, where no on-site data collection is necessary). To facilitate the data collection process, TamoGraph offers three survey modes that can be selected by pressing the corresponding buttons on the tool bar: Continuous (the left button on the illustration), Point-by-Point (the middle button on the illustration),  and GPS (the right button on the illustration) for GPS-assisted outdoor surveys.

IMPORTANT: GPS functionality is available to Pro License users only.

In the default continuous mode, after you mark your initial location on the map by clicking on it, the application scanner continuously scans the air by sweeping through the Wi-Fi channels. When you mark the next location on the map, the data that has been collected between the two clicks on the map is spread evenly along the path between the two data points. This means that your path should consist of straight lines and that you should walk steadily, clicking on the map every time you change direction.

In the point-by-point mode, TamoGraph collects data only when you click on the map. In that mode, you should stay where you are after marking your location on the map, until the scanner completes the cycle. Then the scanner stops, until you mark your next location, where the scanner makes another full cycle. This means that your path can have any shape, but less data will be collected, as compared to the continuous mode, and a smaller area will be covered.

In the GPS mode, the data collection process is similar to the one in continuous mode, but the location is automatically determined by the GPS receiver connected to the computer. Continuous and Point-by-Point surveys can be conducted both indoors and outdoors; GPS surveys can be conducted outdoors only, as GPS receivers cannot receive location data when indoors.

Before you begin, spend some time thinking through your walkabout path. Decide which areas you need to survey and how you are going to do that. Remember that it is quite all right to mix the three data collection modes—that is, you can survey some areas where walking steadily in a straight line is not a problem in continuous mode; you can then survey other areas in point-by-point mode, and then survey the area outside the building in GPS mode. You can also stop the survey at any moment and continue after a break, as you can select several survey segments for data analysis. Once you have thought through your walkabout path, begin the actual survey.

TamoGraph allows you to perform two types of surveys: active and passive (or both at the same time). Every time you start data collection, you will be prompted to select the type of survey, as shown below.

It is extremely important to understand the difference between the two survey types, as they focus on different WLAN characteristics. Please refer to Understanding Survey Types: Passive, Active, and Predictive for more information. When performing an active survey, an additional configuration dialog is displayed before you can start data collection. This dialog is explained in the Active Survey Configuration chapter. Additionally, when a compatible spectrum analysis device is connected to the computer, you will be able to collect spectrum data either in parallel with a passive survey (the first dialog option will be titled Passive Survey + Spectrum Survey) or in spectrum-only mode (another option titled Spectrum Survey will be added to the dialog).

Continuous Mode: To start data collection, click on the Start button (illustrated on the left) and then mark your initial location on the map by clicking on the corresponding spot. Walk along the planned path at a steady pace in a straight line. You should walk a bit slower than you normally do. Every time you reach the end of the straight line on your path (i.e., every time you need to change direction), click on the map again to mark your current location. Data collection stops when you click on the Stop button (illustrated on the right.) If you want to suspend data collection temporarily without stopping your current survey (e.g. when you want to answer a phone call and then continue), click on the Pause button (illustrated on the left) to pause the survey and then click it again to resume. Important: if you paused the survey, you can move freely, but you must return to the exact location where you paused the survey before you resume it, otherwise your survey data will be invalid.

Point-by-Point Mode: To start data collection, click on the Start button. Mark your location on the map by clicking on the corresponding spot. TamoGraph will collect data by scanning the channels twice and display a notification at the bottom of the window when all the data has been collected. Proceed to the next point on your path and mark your location again. Repeat until you have surveyed all the planned points. Data collection stops when you click on the Stop button.

GPS Mode: To start data collection, turn on your GPS receiver, connect it to your computer, and then click on the Start button. Your current location will be displayed on the map with a circle. Make sure that the displayed location matches your actual location. If it does not, you made a mistake while calibrating the map with reference points, and you need to re-calibrate the map. Walk or drive slowly along the planned path. The slower you drive, the more Wi-Fi data will be collected, and the more accurate the data analysis will be. GPS surveys can be conducted outdoors only, in open areas where a GPS receiver can see many satellites. Location data accuracy is directly related to the number of satellites in view. As you move along the path, location data accuracy is indicated on the application status bar, as shown on the illustration. If location data accuracy becomes poor, you may want to stop the survey until more satellites become visible to the receiver (you can click on the data accuracy indicator to display the GPS receiver configuration dialog that displays accuracy level and visible satellites).  Data collection stops when you click on the Stop button.

When you are through with the survey, you can proceed to the data analysis of a passive and/or active survey. However, before you do, it is recommended that you read the next three chapters, especially if you are new to Wi-Fi site surveys. They provide important information about the available types of surveys, their purpose, as well as some valuable tips and tricks to make your site surveying more efficient.