Used to view small (or large) changes in the RF spectrum over time. When scanning begins, the first trace is saved as a snapshot. For all subsequent scans, the snapshot trace is subtracted from the current trace and the difference, i.e. ‘delta’, is displayed. Plotting the data in this way makes it easy to detect RF changes in transmitted signals that occurred since the initial snapshot and is most useful in environments where RF transmissions change over time.
A three-dimensional representation of RF signal transmissions that displays accumulated RF energy as a function of frequency. The power of the signal strength in dBm is shown across the frequency span. A signal strength that appears with a relatively low occurrence is ‘blueish’ in color, whereas increasingly brighter colors are used for signal strengths that occur more frequently. Signal strengths that occur most often are ‘reddish’ in color. Another way of stating this would be to say the Topographic Map uses color to mark the rate of occurrence (i.e. how often) a particular signal strength occurs.
Over time, the Density Chart will approximate the steady-state RF energy signature of the current environment, giving the user a better, more general idea of the environment. This is because the Topographic Map deemphasizes outliers such as intermittent or random signals while at the same time emphasizing signal transmissions that occur more frequently.
Whitespaces And Intermod-Compatible Frequencies
Clear Waves can be used for locating open frequency space in crowded RF environments PLUS frequency coordination — that is, assigning channels that are both free of RF interference and intermodulation distortion. The ability to generate and display a set of intermodulation-compatible frequencies that is uniquely suited to the RF energy and transmitted signals in your environment is one of the software’s more powerful features. Clear Waves can compute a list of frequencies (i.e. a frequency set) that are both free of RF interference and intermodulation distortion. In the Control Panel a user specifies a signal strength to be used as the ‘White Space Threshold’ — frequencies that fall below this threshold are considered open and available and will be included in the intermodulation analysis (i.e. are considered candidates for inclusion in the final frequency set).
The White Space Setting control is used to specify the threshold signal strength (in dBm) below which is considered ‘White Space’. When you adjust this control you’ll also see the horizontal, white line in the Spectrum Trace view move up and down accordingly. Along those frequency spans where the white line is solid and not interrupted by a peak, then this would be considered a White Space region. It is up to the user to determine what is an appropriate threshold for this control — it depends on the environment you are working in and what level of background RF energy you feel can be safely tolerated. As with most things, there are trade-offs. The lower (more strict) the threshold, the less white space and fewer intermod-compatible channel assignments available. The higher (more lenient) the threshold, the more white space and more intermod-compatible channel assignments will be available.
The measurements for White Space regions are used for locating open frequency space in crowded RF environments and are applied to the intermodulation analysis. The computed results show the best channel assignments for setting-up multiple transmitters — as shown in the Intermods & Whitespace view. These channel assignments are free of RF interference and intermodulation distortion. This is most helpful when frequency coordination and RF interference are factors that need to be taken into account when selecting which frequencies or channels to use.
When you right-click the mouse button inside the Intermods & Whitespace chart then a popup menu appears — selecting More Info… dispalys a box (similar to above) that lists all White Spaces and Channel Assignments (the Frequency Set) in table format.
To save the frequency set to a file, from the main menu select File > Create Report…. This allows you to save the Frequency Set, list of white spaces, and current charts to a PDF file.
A 3-dimensional representation of the RF energy data (i.e. signal transmissions), where the X-axis is the frequency scale, the Y-axis is a time scale, and the “Z-axis” is the color scale. Each horizontal line in the Waterfall chart displays the signal strength (as a color) as a function of frequency as measured over the time period of one scan. That is, with each scan (or sweep) a new row is added at the bottom of the Waterfall chart. The color legend to the right shows that stronger signals will appear red and weaker signals will appear blue.
Under the Control Panel’s Scale Settings tab you will find the Waterfall Scale control, which applies only to the Waterfall History view. This control can be used to rescale the signal strengths to better spread them across the range of colors that are used. This is useful when all the signal strengths are large and the Waterfall appears mostly red or when all the signal strengths are low and the Waterfall appears mostly blue. For the best visual effect, ideally you’d like the peaks (strong signals) to appear red and the valleys (weak signals) to appear blue. But sometimes even the valleys have large signal strength values or the peaks have low signal strength values. This control is useful in remapping the color legend to better make use of the colors and how they are spread across the peaks and valleys of the signal strength values.
RF Spectrum Trace
Continuously scans and samples the signal strength (dBm) of RF transmissions within the specified frequency range. By default 3 traces are displayed — Current (green), Maxima (red) and Active (gray). The Current trace displays the signal strength data from the most recent scan, the Maxima trace displays the maximum signal strength for each frequency since the scan session began (similar to a ‘Peak and Hold’ function), and the Active trace displays real-time data as the RF Explorer device is actively scanning. Optionally, a Reference (blue) trace may also be displayed.
In the upper-right-hand corner of the Spectrum Trace view there is a small rectangle that displays the current [x,y] grid coordinates in MHz and dBm. As you move the mouse cursor around the chart, these coordinates are continuously updated.
When you right-click the mouse button, a popup menu appears with several choices you can select from:
◦ Create Marker points or ‘Hot Spots’ using the left mouse button
◦ Full Screen view
◦ Clear Markers
◦ Hide Maxima Trace
◦ Hide Reference Trace
These choices are discussed further below:
Left Button used for creating Marker points or ‘Hot Spots’:
When you select Left Button: Marker Points from the popup menu then subsequent left-clicks create Marker points or Hot Spots that display the corresponding frequency (in MHz) and signal strength (in dBm) for the location in the grid that you just clicked on.
Full Screen view:
When you select Full Screen from the popup menu, the Spectrum Trace view will enlarge to fill the entire screen, and the two lower windows will become minimized. To restore the Spectrum Trace view to its original dimensions, access the popup menu by right-clicking the mouse and select Restore Screen.
Clear Markers from the display:
If the Spectrum Trace view becomes too cluttered with Markers, then these can be removed from the display by selecting Clear Markers from the popup menu.
Hide Maxima Trace:
When you select this option from the popup menu then the Maxima trace is no longer displayed. If the Maxima trace is currently hidden and you wish to display it again, then from the popup menu select Show Maxima Trace and it will once again be displayed in the view.
Hide Reference Trace:
When you select this option from the popup menu, the Reference trace will no longer be displayed. If the Reference trace is currently hidden and you want it to be displayed again, then select Show Reference Trace from the popup menu. In order to show a Reference trace it is first necessary to save a trace to a file.