By comparing user-generated results with images in the database, it's easy to distinguish between pure signals and interference or other spurious signals.
Radio and TV, both analog and digital, second-, third-, and fourth-generation mobile telecommunications, emergency services communications, WLAN networks, and industrial control signals—all these services share frequency bands that overlap to a greater or lesser extent, and can sometimes interfere with each other or be subject to external interference, whether occasional or even intentional. To determine the type of interference, it's essential to know what the actual signal looks like beforehand.
The Narda Safety Test Solutions "Signal Guide" is a collection of signal characteristics in the time domain, including spectra and spectrograms. The images and their descriptions are grouped into categories such as "RF Services" or "Modulation Types." The images can also be displayed in a gallery format for comparison with the unknown signal. The Guide includes an appendix detailing how the images were obtained.
The “Guide to Signs” can be found here