Khanfar Spectrum Analyzer

Technical Specifications:

• Sample Rate: 2.4 MS/s
• Bandwidth: 1.2 MHz
• Update Interval: 50-200ms
• FFT Size: 4096 points
• Supported Hardware: RTL2832U-based SDRs

Additional Features:

• Offline Map Support: Cache map tiles for offline use
• Additional Controls: Latitude/longitude input and max signal distance setting
• Error Handling and Logging: Improved diagnostics and error recovery
• Visual Enhancements: Updated heatmap colors and compass design
• Performance Improvements: Optimized update intervals and thread management

Technical Highlights:

• GPU Backend: OpenGL-powered spectrogram for minimal latency
• Open Source: Fully customizable under the GNU license
• It is getting its name from Phosphor, materials that exhibit slow decay of light, which are used in radar screens and CRT displays. Fosphor is essentially a spectrum analyzer, but it is a beautiful one, a convenient one and very suitable for real-time and burst signal applications.
• This project's main developer is Sylvain Munaut, who is working on this as part of the Osmocom project. Fosphor and GNU Radio are free, open-source projects licensed under the GPL license.

Fosphor UI Elements:

• Live spectrum – a red line showing frequencies of the signal in the window
• Waterfall – the bottom part of the window showing frequencies in time on the time axis
• Histogram – the top part of the window showing frequencies in time as a histogram
• The live spectrum and waterfall are pretty standard, though nicely done, detailed, responsive and clearly colored. The histogram "charges" and "discharges" over time, making it easy to notice short bursts of signal.

New Features Details:

• Frequency Scanning Functionality:
  • Users can set start frequency, stop frequency, step size (kHz), and dwell time (ms) via text inputs.
  • "Start Scan" and "Pause Scan" buttons to control scanning, with keyboard shortcuts ('O' to start/stop, 'P' to pause/resume).
  • Automatically loops from start to stop frequency, stepping by the specified increment.
  • Dwell time adjustable down to 50ms for rapid scanning!
• Preset Scan Buttons:
  • Added preset scan buttons for quick ± range scans around the center frequency.
  • Simplifies rapid analysis of frequency bands with predefined ranges.
• Enhanced Keyboard Shortcuts:
  • '+' or '=': Increase frequency by the step size (default 100 kHz, adjustable via dropdown).
  • '-': Decrease frequency by the step size.
  • 'O': Start or stop the scan.
  • 'P': Pause or resume the scan.
  • Note: "Keyboard shortcuts for frequency tuning (+/-) and scan control (O/P) for faster operation."
• 3D Visualization (Beta 1.2):
  • Interactive 3D spectrum rendering for a deeper understanding of signal behavior
  • Adjustable viewing angles and zoom for detailed inspection
  • Enhanced GPU utilization for smooth performance

Additional Features:

• Zoom: Splits the display vertically and lets you select a narrow frequency band of interest
• Pause: Stops processing and lets you closely examine an interesting signal before it scrolls away
• Scale: Changes the dB scale and offset to hide noise and focus on key signals
• Keyboard Shortcuts:
  • z: Toggle zoom mode
  • a/d: Move zoom frequency down/up
  • s/w: Adjust zoom width
  • q/e: Adjust screen split between waterfall and FFT/histogram
  • space: Pause display
  • (left)/(right): Adjust dB/div
  • (up)/(down): Adjust dB offset

Fosphor Main Parts:

• FFT: Processes every sample at the input in at least one FFT window
• Live Spectrum: IIR average of all computed spectra for smooth responsiveness
• Waterfall: Displays all spectra with potential future aggregation
• Histogram: Statistical view of spectra, perfect for bursts and transients

Source Code

Technical Highlights:

• Multi-SDR Hardware Support:
  • RTL-SDR: Frequency range 24 MHz - 1766 MHz with sample rates up to 3.2 MS/s
  • Airspy: Frequency range 24 MHz - 1800 MHz with sample rates up to 10 MS/s
  • HackRF: Frequency range 1 MHz - 6 GHz with sample rates up to 20 MS/s
• Unified Block Scanning: Transforms multiple independent SDR devices into a single, powerful spectrum analysis system
• Intelligent Frequency Allocation: Devices automatically adjust to maintain appropriate overlap between adjacent SDRs
• Automated Multi-SDR Management: Handles the complexity of coordinating multiple SDRs, presenting a unified interface

New Features:

• Frequency Locking Across Multiple SDR Instances: Creates a continuous spectrum view by intelligently aligning frequency ranges of all connected devices
• One-Control Operation: Control all connected SDR devices through a single interface with synchronized parameter adjustments
• Turbo Scanning with 8ms Dwell Time: Ultra-fast frequency scanning capabilities for rapid signal discovery
• Cross-Device Type Integration: Seamlessly combines RTL-SDR, Airspy, and HackRF devices into a unified monitoring system
• Enhanced User Interface: Scrollable control panel and improved layout for better usability