If you’ve ever used a software-based music player, or an older hi-fi system with an LCD display, then you might have noticed a row of vertical bars, which change sizes in accordance with the music being played.
This is a very simple version of what’s known as a spectrum analyser. It works by splitting the signal into various frequency bands, and displaying the relative volume of those bands. When there’s a big bass drum, the lower bars grow, when there’s a sizzling crash symbol, the higher ones do.
But this is just one kind of spectrum analyser. In a laboratory setting, it’s possible to analyse the spectrum of a variety of signals – including entirely non-audible ones. This is done using a hardware-based spectrum analyser, which works via the same principles – albeit to a much greater level of precision.
These more advanced spectrum analysers look a little bit like oscilloscopes. The key difference is that they operate in the frequency domain, rather than the time domain. This makes it possible to see, at a glance, whether a particular frequency is prominent.
This information can be used for many different purposes.
Telecommunications and Wireless Networks
Most obviously, spectrum analyzers are used to monitor signal quality in telecommunications. If a particular frequency is prominent, it might interfere with the radio signals that help wireless networks to function. By picking out these problems, an engineer can troubleshoot them much more quickly and effectively.
EMC Testing and Regulatory Compliance
There are some devices that naturally emit radiation and electromagnetic noise. In some cases, these emissions might cause the device in question to fall on the wrong side of the rules for a certain territory. A spectrum analyser might allow an engineer to identify interference before it becomes a problem.
Audio Engineering and Sound Analysis
As we’ve mentioned, spectrum analysers are often used in the world of audio. While most audio professionals will rely on their ears, a spectrum analyser can be very useful in pinpointing undesirable frequencies and subduing them (or cutting them out entirely).
General RF Testing and Development
More generally, spectrum analysers can be used to debug and troubleshoot any circuit that relies on radio frequencies. They might be used as part of the quality control processes on a production line, or they might be used at the research and development stage, as a given product is first being developed. By constantly analysing the signals being emitted, engineers can refine their products much more quickly, and ensure excellent real-world performance.
