Recently, M. Khanfar released a new free program, "Analog Radio Hunter," described as a "professional RF analysis and monitoring application built around GNU Radio and Fosphor." The software currently supports RTL-SDR, Airspy, and HackRF. Khanfar writes:

Analog Radio Hunter is a professional RF analysis and monitoring application built around GNU Radio and Fosphor.

It is designed to scan large RF spans, quickly lock onto active signals, and monitor analog transmissions with NFM, AM, or WFM audio demodulation.

• Real-time FFT + waterfall spectrum display
• Fast scan with dwell, pause-on-squelch, and skip-ignored channels
• Detection list with hits, timestamps, and smart deactivation
• Favorites profiles with monitor and favorites-only scan modes
• Built-in recorder with auto-record and event log
• Dedicated WFM broadcast receiver with presets
• Multi-SDR device support (RTL-SDR, Airspy, HackRF) with auto-detect and device switching
• NFM and AM audio demodulation (in addition to WFM)
• Peak-follow in span (auto-tune to strongest signal inside the current MS/s window)
• Frequency list filtering to skip/mute ignored channels
• Scan and detection profiles (save/load named presets)
• PPM correction for RTL-SDR calibration
• Spectrum interaction controls (cursor readout, click-to-tune, wheel step, drag-pan)
• Recorder options (record when muted, timestamp/frequency in filename, beep on favorite)
• WFM de-emphasis selection (50/75 µs) and preset management
• Audio Output menu with refresh (route audio to speakers, VB-Cable, or USB output)
• Signal Stability Filter with Min Open + Grace timing and per-target routing
• Histogram IQ Rec with live IQ follow controls and inspectrum integration
• Auto Squelch Calibrate (noise floor + margin) for faster field setup
• Smart Deactivate dual-layer logic (time-based + hit-rate busy rule)
• Favorites cooldown auto-reactivation for busy channels
• Favorite TX tones (Tone 1-9), edge selection, and tone test buttons
• Learning Mode hover guidance for faster onboarding
• Status bar live metrics for Last, Active, Favorite, Peak SNR, and Level

Unique scanning and detection approach: Traditional sweep scanners only see the center frequency they step to. Analog Radio Hunter monitors an entire chunk of spectrum at once and reacts to peaks inside it. That is a major differentiator.

 

High-Impact Capabilities

• Wide-span reactive scan engine that hunts activity across a full chunk, not one center point at a time.
• One-click IQ capture and histogram visualization with follow and idle flow controls.
• Carrier-resilient channel management using Smart Deactivate + favorites cooldown logic.
• Field-ready setup speed using Auto Cal squelch and persistent live status metrics.
• Operator-selectable audio routing to speakers, VB-Cable, or USB audio output devices.
• Operational clarity from GUI color heatmaps, scan debug reasons, and learning-mode tips.

Signal Stability Filter: Logic and Tuning

• Purpose: reject short squelch flicker and noisy open/close chatter before actions trigger.
• Min Open (ms): raw squelch must stay open this long before stable-open is accepted.
• Grace (ms): stable-open is held briefly after raw close to avoid tiny dropouts.
• Apply targets: Detection, Rec+Alerts, Scan Hold, and optional Audio Out gating.
• Start values: Min Open 150-250 ms, Grace 40-80 ms, then tune by channel behavior.

Like his other software, which we previously covered, it is free but not open source. Anti-virus programs may flag the software as suspicious due to heuristics. We believe this to be a false position, but please proceed at your own risk.