Why Waterfall
WHY Waterfall is a real-time audio spectrum and waterfall analyzer designed for radio enthusiasts who want a fast, intuitive way to visualize and listen to signals directly from their receiver.
It is especially useful for radios that do not include a built-in waterfall or spectrum display, turning any standard receiver into a powerful signal analysis tool using only its audio output.
The program focuses on simplicity, responsiveness, and practical usability — transforming audio into a clear visual and interactive signal experience.
Here is beta version 2 (3 is latest) running in full-span mode. Peak detection has now been added. In this example, the detected peak is the beacon SK6VHF.
After double-clicking on the trace, the span can be narrowed for more precise tuning. Adjust the waterfall gain as desired. To return to full span, right-click in the waterfall.
Below is a recorded audio sample from the screenshots above. The receiver is an old FT-290R II located inside the shack with a small rubber antenna. The signal is barely audible from the normal speaker.
why_144-406000_20260403_135036.wav
Key Features
Real-Time Spectrum & Waterfall
- Real-time waterfall and spectrum display
- Works with any radio via audio output
- Click-to-tune and fast navigation
- Peak detection and signal highlighting
- Adjustable filters and noise reduction
- Audio recording and playback
- Designed for weak signal work
Click-to-Listen Signal Monitoring
- Click any signal in the spectrum or waterfall to instantly monitor it
- Direct audio extraction using real-time DSP
- Ideal for CW, beacons, weak signals, and general signal hunting
Adjustable Filter Bandwidth
- Multiple selectable bandwidths:
- Narrow CW (100–500 Hz)
- SSB (1.2–2.4 kHz)
- Wide / FM (up to 12 kHz)
- Optimized for both weak signal work and wideband audio
Noise Reduction
- Adaptive real-time noise reduction for improved intelligibility
- Selectable strength:
- Mild
- Normal
- Aggressive
- Especially effective for weak CW and narrowband signals
Monitor Gain Control
- Independent monitor volume control
- Wide dynamic range for weak signal amplification
- No need to adjust system audio levels
Recording
- Record incoming audio directly to file
- Capture signals for later analysis
Flexible Frequency Control
- Manual frequency entry (works on any band)
- Accurate frequency scale across full audio span
- Click-to-tune functionality
- Calibration support for precise alignment
Zoom & Navigation
- Full 24 kHz span at 1× zoom
- Multiple zoom levels for detailed inspection
- Smooth switching between wide scan and focused view
Input Level Monitoring
- Real-time input level meter with peak hold
- Clip detection for optimal signal setup
Designed For
Ideal for:
- Older radios without waterfall display
- A better view of your band than most built-in waterfalls
- Portable / simple setups
- Weak signal listening (CW, beacons, digital)
Philosophy
WHY Waterfall is built to be:
- Fast – minimal latency, real-time response
- Simple – no unnecessary complexity
- Practical – designed for actual on-air use
No drivers, no SDR hardware required — just connect your radio’s audio output and start exploring signals.
Download beta version 3:
Note: the executable is still named WHY 847 because support for the Yaesu FT-847 is part of an ongoing project.
If you like the program and feel to donate use the Donate button.
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