MAKING YOUR WIRELESS CHANNELS VISIBLE….
The new Invisible Waves X combines radio spectrum analysis with the ability to select and monitor your wireless channels as well as other frequencies of interest, detect and identify potential interference, listen to the signals, seek clear spectrum, and set various alarms to warn of impending RF problems-creating what has been billed an “RF Command Center.” The solution includes both RF scanning hardware and a comprehensive software suite providing the various functions, and uses your PC for processing and display of the signals.
THE IWX HARDWARE
The Invisible Waves system consists of an RF scanner, power supply, articulating antenna, and connecting cables. The system can be used and stored in its fitted case, or can be mounted in a rack tray. An optional Smart LiPO battery pack may be purchased for use in areas where an AC connection is unavailable; it will typically provide power for three to six hours of use.
The scanner connects to a laptop or desktop PC via a four-foot multi-pin to USB cable. A three-foot audio cable ending in a 1/8-inch stereo mini-jack is permanently wired to the scanner, providing a line-level audio output of any selected frequency for monitoring purposes.
The software operates on a PC running Windows XP, Vista, or Windows 7, and requires a CPU with a speed of 2.0 GHz or above, and at least 2 GB of memory.
IWxAV Version for Higher Frequency RF
The standard Invisible Waves system covers the radio spectrum from 9 kHz-1,800 MHz. The optional WinRadio Down Converter allows the scanner to cover frequencies up to 3.5 GHz, for your 2.4 GHz wireless mics, WiFi, and other higher frequency equipment.
The down converter connects to the scanner's antenna connector, and gives the user the ability to view the spectrum in two 1,800-MHz blocks-basically zero to 1.8 GHz and 1.7 to 3.5 GHz. The range to view at any given time is selected within the software, and the scale values within the Spectral Trace window change appropriately.
THE INVISIBLE WAVES X SOFTWARE
The Invisible Waves X software is the display and control center for the system, with a rich feature set and the flexibility to adjust the display and hardware settings to meet your wireless management requirements. The four main components are:
Spectral Trace View - A graphical plot of the frequency sweep data in real time, with the ability to zoom, mark peaks, change ranges, and much more.
Heatmap View - A cumulative plot of the historical sweep data during an event or show, so that a picture of the RF
environment over time can be recorded and analyzed.
Master Status Display - An area of the screen where selected frequencies can be monitored in real time, with any changes or problems instantly visible via visual (and audio) alarms.
Dockable Status/Settings Panels - Where your most frequently used functions and their settings can be accessed via a mouse click or key stroke.
A conventional drop-down menu of features and functions is provided along the top of the screen. In addition, a series of graphical buttons just below the menu gives one-click access to the main features of the scanner. This tool has so many capabilities that I will highlight some of the critical ones.
FREQUENCY SWEEPS
When the Spectral Trace View is first activated in a session, the system takes several sweeps of the selected spectrum to gather enough detailed information to display an accurate trace of the RF environment and its signals. The first sweep collects information at selected frequencies, and the following sweeps collect additional data about the surrounding frequencies, until the entire range is mapped.
Based on the overall range of the sweep (for example, the 100-MHz block between 520 to 620 MHz), a drop-down menu in Sweep Settings allows you to set the
scan resolution value. The higher the resolution, the more points that are sampled and the more time the individual sweep will take. The end result, however, is a detailed view of the RF activity. Within Spectral Sweep Settings, the user can select to view any or all of the Current, Average, Maximum, and Shadow (previous) traces.
An Adaptive Sweep mode provides alternating moderate-resolution sample sweeps across the entire spectrum selected in the Spectral Trace view, followed by a detailed sweep that “concentrates” on the locations where significant RF activity is detected. This Adaptive Sweep can take a while to cover the selected spectrum, but when it is through, the useful detail is revealed.
CLICK-TO-LISTEN
The Invisible Waves X system allows you to listen in to any selected analog signal, be it your wireless mic, in-ear monitor, intercom, or other wireless device, as well as FM radio and other broadcast signals. Even if the transmission is digital you can monitor the particular digital noise to potentially identify the source.
By clicking the listen button in the software, a scrolling cursor can be pulled across the Spectral Trace display, and the RF signal is demodulated. The line-level audio appears on a mini-stereo connector and can be plugged into the computer microphone jack or into a mixer channel for monitoring. Signals of interest (such as your wireless mic channels or radio stations) can be placed on the Master Status Panel for easy access, and then directly monitored throughout the production. Also in a production setting, when an unknown signal appears, the ability to listen to it may help identify the source.
MASTER STATUS PANEL
After you have used the Spectral Trace View with the sweeps to determine what RF signals are in the production environment, and have seen where your wireless mics and other equipment fall in the spectrum, the next step is to move those mic frequencies to the Master Status Panel and give them each an identifying name.
From there, you are able to monitor the activities of those selected channels on an ongoing basis throughout the event-including frequency, signal level, the ability to listen to a channel with a mouse click, and be warned visually/audibly of a potential problem. Signal peaks can be selected by dragging or right-clicking from the Spectral Trace or Signal Peaks windows.
ALARMS
Invisible Waves X allows the user to set a signal-level threshold as an aid to monitoring your wireless channels, as well as warning you of rogue frequencies that might appear during a production. For channels in the Master Status Panel, the alarms will flash a yellow border around a particular channel if the signal level drops too near the threshold, and that border will turn red-accompanied by an audio alarm-if it drops below threshold.
ABILITY TO SAVE SETUPS
Once you have set up a session with your selected wireless channels in the Master Status Panel, selected your thresholds and your scan range in the Spectral Sweep, and made any other adjustments to customize the view to your liking, you can save this information to a file that can be reopened at a later time. It is similar to saving scenes in other software, and speeds up the process of setup and monitoring for the next event.
EXPERIENCES IN INITIAL SETUP
Because Invisible Waves X uses the computer for display and monitoring, it is subject to the settings and quirks of the particular computer and operating system. As I was learning to use the tool and clicking on various buttons, I managed to crash it a couple of times. Also, the computer settings seem to affect the screen configuration and layout.
Setting up the Click-to-Listen feature through the computer microphone jack had a couple of false starts, but it worked the first time and then either my computer or I changed the audio settings during a restart and I didn't hear the audio at first-and then with some perusing of menus got it back. Once set up and with a bit of familiarity, it is not difficult to put the scanner into action.
EXPERIENCES IN USE
I used the Invisible Waves X system in a test context, with various UHF and 2.4 GHz wireless microphones and a laptop PC. All in all, it performed well in scanning and highlighting RF signals from both the wireless equipment and the environment, and in presenting that information in usable ways.
One thing that was surprising at first is that traces build slowly when initially scanning a frequency range, so the peaks are not immediately visible. The scanner samples across the frequency range, at an increment that you can set from a dropdown, and then on subsequent passes gathers data on either side of these points to build the spectral display. The recommended Adaptive Sweep will take more time initially, but generates much more detail in each pass; when it completes a pass the display will typically show the detailed peaks. I've concluded that the user needs to learn the best combination of wider, faster sweeps and the Adaptive Sweep to build an accurate spectral display within a reasonable time.
If you are using both VHF/UHF/900-MHz and 2.4-GHz wireless mics, you will be able to monitor only one of those frequency bands at a time-since the split point for the down-converter is 1.8 GHz. Even when all of the wireless units of interest are on the Master Status Panel, you will receive an “Out of Range” notice on those frequencies that are above/below that split point. This is something to be aware of, but is not likely to be a problem because the few 2.4-GHz digital wireless products are typically quite reliable, with robust interference avoidance algorithms; you can also monitor their performance on their receiver front panels. When you switch ranges in the software, you will be able to check the performance of the other wireless group in Invisible Waves X.
CONCLUSIONS
The Invisible Waves X spectrum analyzer is a welcome addition to the tool set of users with multiple wireless channels, changing production requirements and equipment from event to event, and those who tour with wireless in often crowded RF locations. It has always been a challenge to second-guess the wireless environment and keep interfering signals from compromising the presentation. Invisible Waves X provides a window of visibility and control in a powerful and cost-effective manner, ideally saving both time and frustration for the wireless portion of your production.
