METAL_DETECTOR
SPECTRAL_G4 // CORE_AI
Pushing the limits of traditional VLF detection. Spectral-G4 harnesses the power of the STM32G4 processor and an external 18-bit SAR converter to analyze the phase of three harmonics simultaneously. This is more than a detector – it's a mobile geophysical lab integrated with local AI.
Spectral signature analysis allows for precise discrimination between ferrous and non-ferrous metals even in extremely difficult ground conditions. The system operates on raw I/Q vectors.
- [01] PHASE_SENSITIVE_DETECTION (PSD)
- [02] VECTOR_GROUND_REJECTION
- [03] SPECTRAL_SIGNATURE (AI)
CORE_SYSTEM_
COMPONENTS
CODE AND DOCUMENTATION: PARTNERS ONLY [ REQUEST_ACCESS ]
FREQUENCY_ENGINE
F_CORE // Simultaneous analysis of 4.5kHz, 13.5kHz and 40.5kHz.
Detecting phase shifts for each harmonic separately. Allows building a precise spectral signature of the object (Spectral_ID).
ADC_ULTRA // 18-bit PulSAR for extreme dynamic range.
Fully digital ground compensation. Only the probe is analog (preamp and coil nulling) – everything after it is data, allowing for lossless Software-Defined filtering.
AI_BRAIN // Target classification via neural networks.
Instead of simple VDI thresholds, AI analyzes the full vector trajectory during coil movement, recognizing signature shapes of difficult targets.
SPECTRAL_G4 //
COMPLETE_DETECTOR
Spectral-G4 complete: the controller in a sealed enclosure on the grip, keypad under the thumb, a khaki shaft and a 12×9″ DD coil. On screen: Target Radar, a cloud of recent readings where the angle is VDI and the radius is signal strength.
128 × 157 mm wedge body designed for IP68. LCD window with a PMMA pane, 6-key membrane keypad sized for gloves, 2 M12 connectors.
The main board with the display sits in the enclosure with the screen under the LCD window. The keypad connects to it by a ribbon through a sealed slot in the lid.
The upper part of the detector (controller, grip and armrest) also plugs into a carrier profile with two rectangular antennas: RX flat at the front, TX upright at the back. Two-box mode for large, deep objects.
Board design is complete: every connection routed and checked (DRC), fabrication files prepared. Photos of the assembled boards will follow after fabrication.
4 layers, 105 × 134 mm. 240×128 graphic display, membrane keypad connector.
STM32G474, 18-bit PulSAR converter with a precision reference, RX path routed to ADI application notes, transmitter H-bridge, audio amplifier.
2 layers, 46 × 34 mm. Differential RX preamplifier and digitally controlled coil nulling with a toroidal transformer.
HOW_VDI_WORKS //
TARGET_RADAR
The heart of the detector. The angle is VDI, the target phase: from ferrite (−90°) through iron and foil (0°) to silver (+90°). Each point is a filter peak at the ID of the pass, so repeated swings over the same target build a cluster. Three frequencies measure the phase together and catch iron that poses as a good target. Pick a target and change the depth.
G4_UNIT_RESERVATION
G4_SET // FOUNDER_PACKAGE
CO-CREATOR // Receive a prototype in exchange for supporting development.
SERIES_0: 4 of 10 units reserved – 6 spots remain. Shipping planned for January/February 2027.
Access to 'Series 0' prototype at production cost. Direct contact with the creator, influence on functionality. Detector dispatch: January/February 2027.
Project support of 550 EUR (offer valid only until the end of 2026). Detector will be dispatched in January/February 2027. Ideal for enthusiasts who want to help bring this gear to life and be the first to receive it.
takzen.app@gmail.comMULTIDIMENSIONAL_
OPERATION
Pure vector compensation without motion filters. Allows for target detection at zero coil speed, ideal for precise pinpointing and analysis of deep signals.
Multi-stage band-pass filters designed on STM32G4. Maximum dynamic range while eliminating ground mineralization influence.
Not just the base phase. We analyze the 3rd and 9th harmonics (13.5 and 40.5 kHz), allowing for unique discrimination of objects with similar VDI but different material structure.
G4_ADVANTAGE //
Signal_
Characteristics
Target figures – to be verified by measurements on the prototype.
Vector Ground Balance system eliminates soil influence with 0.01-degree phase accuracy, ensuring stability in difficult terrain.
Thanks to the 18-bit SAR converter, the system detects microvolt-level signals previously hidden in quantization noise.
Agentic signal analysis. AI decides in real-time whether a signal is worthy of attention or just EMI interference.
Processor latency below 1ms. Every signal reaches the audio directly, without delays typical of legacy signal processors.
NEURAL_NETWORK //
LIVE
The neural network sees the whole swing on three frequencies at once. When a nail lies right next to a coin, both are under the coil together and give one signal: the network recognises the overlap and gives the VDI of the hidden coin. Further apart, they give two separate signals and two verdicts. Pick a target and change the depth.
PROJECT_CREATOR // Krzysztof_Takzen
I am Krzysztof. My goal is to redefine the modern metal detector by integrating low-level DSP with sovereign AI models. Spectral-G4 is the fruit of my search for the perfect balance between analog sensitivity and digital precision.
I specialize in Embedded Systems, STM32 microprocessor architecture, and digital signal processing. This project is a 'Code-First' manifesto in the hardware world – rigorous engineering and algorithm transparency.
As part of the Spectral-G4 project, I fulfill my mission through:
- >> Development of an open DSP platform for hobbyists
- >> Implementation of neural networks on microcontrollers
- >> Designing ultra-low-noise analog signal paths
REPOSITORIES //
DOCUMENTATION
FIRMWARE // STM32G4
Repository with the architecture overview, code and project status. Access for project partners only.
SYSTEM_OVERVIEW
Public technical documentation including block diagrams, interface specifications (SPI/I2S), and analog signal path characteristics. Full schematics exclusive to partners.