Spectrum Analysis doesn’t have to be tricky. I like comparing spectrum analysis to detective work. With the right tools almost anyone can be a spectrum detective. When a crime occurs in the movies one of the first questions investigators ask each witness is “what were you doing at the time of the event?” This question is pretty effective because it will show any inconsistencies in any of the subjects’ testimonies. Sometimes detectives don’t find a lead until they assemble a time line of all of the events to make sure each witness’s line up. A time line of events can be equally effective in spectrum analysis
Good software tools will allow any spectrum detective to ask the same question “what happened from 12:00pm to 1:00pm?” and each witness would respond instantly. This is the fundamental principle behind MetaGeek’s most popular spectrum analysis software, Chanalyzer Pro. Some spectrum analysis programs have one panel showing an hours worth of data, another showing 10 seconds, and another showing a minute and a half. All of the panels in Chanalyzer Pro use a unified time range of data, creating the perfect time line to establish a baseline and to identify potential points of interference in real-time or in the past.
Time segment spectrum analysis shows how bad the problem was when it occurred.
Let’s change the analogy to focus on how the visualizations in Chanalyzer Pro can aid spectrum analysis. A seismometer measures the vibrations of the earth. Most commonly it is used to record earthquakes events. The seismometer draws straight lines the majority of the time it monitors seismic activity. This can be called the baseline or normal activity. When an earthquake occurs it draws large scribbles giving researchers a clear picture of the event.
The waterfall view in the Chanalyzer Pro spectrum analysis software does the same thing for your RF environment. Like the seismometer it is a historical record of amplitude levels but instead of scribbles the software uses a range of colors. It shows when the environment changed and to what scale as well.
Browsing by time segment is one of the most vital features in spectrum analysis solutions.
RF environments are always changing and effective spectrum analysis software can show how drastic that change may be. The adjustable time span in spectrum analysis is necessary for mobile site surveys. Old data from the kitchen will skew the visualizations of the office unless the software can account for a start and end time.
The results of spectrum analysis software without an adjustable time span can be compared to exposure values in photography. The exposure is turned on for too long to catch the details and it is especially poor in mobile environments. Car headlights turn into bright lines going across the image. The same can be true in spectrum analysis as a user walks through a building. With a shorter capture time frame the patterns of transmitting devices are crisp and clear. Recognizing the patterns of interference can be done quicker and on the fly. Many users of Chanalyzer Pro can build full reports as they do the site survey.
Chanalyzer Pro assigns each Wi-Fi (or ZigBee) Channel a grade based on the spectrum activity of any transmitter in its channel frequency range. The grades adjust automatically to the new time spans defined in the navigational waterfall. The higher the grade, the more clear a channel is. When the time range of the grade drops to 0 in the time range of 1:53 to 1:55 and returns to 77.
Chanalyzer Pro graphs real-time spectrum activity and generates density maps of the the RF activity. A density map is great for tracking patterns devices make in the spectrum. Every wireless device creates a pattern in the spectrum similar to walking paths in the snow. There may be a lot of seemingly random foot prints but from a birds perspective, you can tell where people are traveling. In Chanalyzer Pro the denser “paths” the RF activity take appear brighter.
Good density maps of spectrum activity continually adjust to a range of time otherwise the patterns eventually blur. Each view must drop off old data as it does in Chanalyzer Pro. Professionals typically maintain a time span of 1 to 2 minutes when they are walking to keep the data on the displays relevant to their location. As we mentioned earlier the kitchen should have a different looking spectrum than the warehouse and a blurry combination of both is never an accurate picture.
Time Segment Spectrum Analysis Tips:
- Use 2 minutes or less for on-the-go mobile site surveys or troubleshooting.
- For troubleshooting intermittent issues, leave Chanalyzer running and create a recording.
- Look for significant changes in the waterfall view to narrow in on for device identification.
Chanalyzer Pro is the ideal tool for troubleshooting interference by time segments. It quickly accesses any range of time to graphically display what caused interference and how bad it was. Download a trial of Chanalyzer Pro and see for yourself. You can also request sample recordings of WLAN interference from our support team.