At a racing event, a damaged VTX was broadcasting at full power on two channels simultaneously, interfering with another pilot. A spectrum analyser was essential for diagnosing this issue—two peaks at different frequencies were clearly visible when only the damaged VTX was powered on. This project makes this critical diagnostic tool accessible to every pilot and race organiser.
What is Hertz Hunter?
Hertz Hunter is a "poor-man's RF Explorer" for FPV drones. It's a DIY spectrum analyser that scans the 5.8GHz frequencies used by FPV video transmitters and displays the signal strength on a small OLED screen. It's designed to be:
Key Benefits:
Why You Need a Spectrum Analyser
A spectrum analyser is essential for race organisers and serious pilots. Here's what it helps you diagnose:
- Find VTX interference — Quickly see which frequencies are in use and spot conflicts
- Diagnose malfunctioning VTXs — Detect VTXs broadcasting on wrong frequencies or multiple channels
- Identify background noise — Find sources of RF interference at your flying field
- Verify VTX output — Confirm your VTX is actually transmitting on the channel you set
- Race day troubleshooting — Essential tool for resolving video issues quickly
At a race event, one pilot's damaged VTX was broadcasting at full power on TWO channels simultaneously—knocking out another pilot's video feed. Without a spectrum analyser, this would have been nearly impossible to diagnose. With Hertz Hunter, the dual peaks were immediately visible on the graph.
Features
Frequency Scanning
Hertz Hunter uses a common RX5808 video receiver module to scan the FPV frequency bands:
- Standard band: 5645MHz to 5945MHz (covers most FPV channels)
- Low-band: 5345MHz to 5645MHz (for low-band channels)
Selectable Scan Resolution
Input Options
Multiple ways to control the device:
- Three buttons: PREV, SEL, NEXT for simple navigation
- Rotary encoder: Turn anticlockwise (PREV), click (SEL), turn clockwise (NEXT)
Additional Features
- Battery monitoring with low battery alarm
- RSSI calibration between known low and high values
- Signal strength display for selected frequency
- Settings persistence saved between reboots
- Wi-Fi API for integration with other software
- USB serial communication with official client program
Getting Started
The Hertz Hunter project is fully open source and well-documented on GitHub. Here's everything you need to build your own:
Full source code, documentation & build guides
GitHub Documentation:
- HARDWARE.md — Hardware designs and component list
- SOFTWARE.md — Software setup and firmware flashing
- USAGE.md — Firmware usage and settings guide
- API.md — API documentation for Wi-Fi integration
- USB.md — USB serial communication documentation
What You'll Need
The build uses readily available components. The total cost should be under $60 AUD:
Core Components:
Check the HARDWARE.md file on GitHub for the complete component list with recommended suppliers and exact part numbers.
Future Development
The project is actively developed with exciting features in the pipeline:
- Custom PCB — Integrated power management circuitry for a cleaner build
- 3D printed case — Designed for the custom PCB
- Web interface — Interact with the scanner and view detailed graphs (currently in development on the
web-uibranch)
Released January 21, 2026, this version adds USB serial communication for connecting to client programs on your PC. Check the release notes for full details.
Summary
Hertz Hunter puts professional-grade diagnostic capabilities in the hands of every FPV pilot and race organiser. For under $60 and a few hours of building, you'll have a tool that can save race days, diagnose mysterious video problems, and help maintain a clean RF environment at your flying field.
DIY Build
~$60 AUD + a few hours
Commercial
$200-500+ for RF Explorer