Spectrograms are a type of waterfall display that plots the spectrum activity over time. As in a typical spectrum display, the start frequency is on the left-hand side and the stop frequency is on the right-hand side. Time is the on Y-axis and color indicates signal amplitude—red being the highest amplitude and black being the lowest. The spectrogram is composed of the peak detected data from the persistence display, and the amount of spectrum data aggregated is defined by the user.
With these controls the user can record the data for long periods of time (hours) and then export and share the results. This is especially useful when there is a stubborn interference problem and the spectrum needs to be monitored for a long time. In the event that you are dealing with an intermodulation issue, the spectrogram can help determine the fundamental elements of the mix.
Keep in mind that with RTSAs the spectrum information is instantaneously measured for the entire time span. This means that we can use the data to perform a visual carrier correlation to confirm the timing relationships between source carriers and intermodulation products.
Interference is a meddlesome guest in our wireless world that will never leave. The best solution to this thorny problem is to become good hunters with real-time spectrum analyzers whose displays are up to the task of pin-pointing and displaying interfering signals no matter how elusive.
About the Author
Dean Miles is a senior EMEA Technical Marketing Manager at Tektronix responsible for Tektronix’ High Performance Product Portfolio. Dean has held various positions with Tektronix during his more than 20 years with the company, including Global Business Development Manager for Tektronix RF Technologies and Business Development Manager for Tektronix’ Optical Business Unit. Dean has presented Tektronix’ technologies in more than 80 countries around the world, met with more than 10,000 engineers and had more than 40 technical papers published.