Real-Time Spectrum Analyzers (RTSA)

A Real-Time Spectrum Analyzer (RTSA) is a device that continuously processes all signal samples within a given bandwidth without gaps. It uses Fast Fourier Transform (FFT) to convert time-domain data into frequency-domain insights, enabling the detection of transient or elusive signals. RTSA ensures gap-free analysis, which is crucial for observing dynamic signal behavior in real-time.

Traditional spectrum analyzers use swept or block-based FFT methods, which can miss short-duration signals due to gaps in data capture. RTSA, on the other hand, provides continuous, gap-free analysis, ensuring that no signal behavior is missed. This makes RTSA particularly effective for detecting transient and agile signals.

• Provides a more accurate picture of the signal environment. RTSAs do not rely on taking samples of the signal at discrete points in time. Instead, they analyze the signal continuously, providing a "true" representation of the signal's behavior.
• Faster measurement setups and easier identification of signal anomalies.
• Easily configured to display only the information that is important to you. They offer great flexibility and insight into your signal environment.

Probability of Intercept (POI) refers to the likelihood that an analyzer will detect a signal of a given duration and amplitude. In RTSA, POI is often expressed as the minimum signal duration that can be detected with 100% certainty. POI is influenced by factors such as sampling rate, FFT size, windowing function, and noise floor.

Six key factors influence POI in RTSA: sampling rate, time-record length (FFT size), windowing function, window size, FFT overlap, and noise floor. These parameters determine the minimum signal duration that can be reliably detected and measured with full amplitude accuracy.

A frequency-mask trigger activates when a signal crosses predefined frequency and amplitude thresholds. This allows RTSA to isolate specific signals in dynamic environments and initiate measurements or data capture based on signal behavior.

RTSA uses overlap processing and optimized window functions to ensure accurate amplitude measurements for short-duration signals. Overlap processing allows successive FFTs to share samples, improving the likelihood of capturing transient events with full amplitude accuracy.

Combining RTSA with VSA enables detailed post-processing, including demodulation and time-domain analysis. Captured signals can be replayed, zoomed, and analyzed using real-time analyzer software like Keysight’s 89600 VSA, providing a comprehensive view of signal behavior.

RTSA is used for detecting interference, characterizing bursty or agile signals, validating wireless system performance, troubleshooting transient issues, and ensuring compliance with spectral masks. Its gap-free analysis and triggering capabilities make it ideal for dynamic and complex signal environments.