The case itself is a treat, as it borrows design elements from another bit ... The pains he went to to get the spectrum analyzer working, including a deep dive into FFT, are impressive.

9 kHz - 3 GHz Spectrum Analyzer Boasts High-End Specs High specification spectrum analyzer evaluates signals from 9 kHz to 3 GHz. Real-Time Spectrum Analyzer Boosts Mid-Range Performance RSA5000 ...

For example, whereas an oscilloscope would show total noise level, a spectrum analyzer would show the noise as related to frequency. Available in both analog and digital models, digital analyzers ...