Vadelma RX III Experimental
Vadelma RX III is the experimental SDRplay-based member of the VadelmaRX receiver family, used for HF, VHF and FM reception, DX monitoring and development of new OpenWebRX+ receiver features.
Welcome to Vadelma RX III Experimental. RX III is the development and experimental receiver of the VadelmaRX system, built around SDRplay and a locally enhanced OpenWebRX+ installation.
Unlike Vadelma RX I and RX II, which are primarily dedicated HF receiving systems, RX III is designed as a more flexible multi-band platform for experimenting with HF, VHF and FM reception, receiver profiles, signal processing and new VadelmaRX user-interface features.
The receiver is located in Kangaslampi, Jyväskylä, Finland. Multiple receiver profiles are available for different frequency ranges and listening purposes, including shortwave broadcast bands and FM broadcast reception.
RX III also acts as a practical development platform. New VadelmaRX controls, visual features, spectrum tools and OpenWebRX+ modifications may appear here before they are introduced on the other Vadelma receivers.
Experimental means experimental: settings, receiver profiles and locally developed features may occasionally change while the system is being tested and refined.
SDRplay Receiver
- SDRplay-based wideband receiver platform
- Multiple receiver profiles for HF, VHF and FM reception
- Runtime AGC and RF gain control directly from OpenWebRX+
- Band-specific profiles optimized for different monitoring tasks
- Suitable for both shortwave DX listening and FM broadcast monitoring
- Used as the experimental hardware platform for VadelmaRX development
Smart Bandwidth
- Manual 4 / 6 / 8 / 10 kHz presets
- Custom filter detection
- Smart Auto BW
- Automatic bandwidth selection using smoothed FFT SNR
DX-Focused Receiver Controls
- Receiver modes reordered for broadcast and DX listening
- AM, SAM, LSB, USB and DRM placed first for quick access
- Compact AGC, RF gain, bandwidth and EQ controls
- Receiver profiles tailored for individual bands and monitoring tasks
- Fast switching between HF, VHF and FM receiving environments
- Receiver panel optimized for rapid tuning during DX sessions
VadelmaRX UI Theme
- Custom VadelmaRX user interface theme integrated into the native OpenWebRX+ theme engine
- Deep navy and petrol-blue instrument-style colour palette
- Warm orange accent for active receiver modes and selected controls
- Cyan and blue-grey accents reserved for signal analysis and status information
- Custom control surfaces for AGC, RF gain, bandwidth and audio EQ
- Available directly from both the receiver UI and OpenWebRX+ settings
- Designed to retain the familiar OpenWebRX+ layout while giving VadelmaRX its own visual identity
VadelmaRX DX Waterfall
- Custom waterfall colour theme optimized for HF DX monitoring
- Very dark navy noise-floor region for a calm low-level background
- Expanded blue and cyan range to improve visibility of weak carriers and marginal signals
- Teal, green and muted yellow transitions for medium-strength signals
- Warm orange and red tones reserved for stronger signals
- Designed to preserve useful visual dynamic range instead of turning weak signals into a rainbow display
- Works together with the existing optimized FFT, overlap and automatic waterfall-level settings
- Available as VadelmaRX DX Theme alongside the standard OpenWebRX+ waterfall themes
Vadelma Watch
- Dedicated toggleable DX analysis panel integrated into the OpenWebRX+ receiver UI
- Four compact analysis cards arranged in a 2 × 2 layout
- SNR Watch – live 60-second SNR history with peak, fade depth and trend direction
- Signal / Noise – simultaneous signal and noise-floor tracking using a shared scale
- 5 Min Trend – longer-term SNR behaviour with average, direction and minimum / maximum values
- Events / Peaks – records only meaningful events such as SNR peaks, fades and noise changes
- Signal-state classification including Stable, Improving, Fading and Noise Rise
- Subtle colour coding for rapid visual interpretation without distracting from listening
- Opened from the dedicated Watch button in the receiver header
Shortwave SKED
- Integrated shortwave broadcast schedule directly inside the OpenWebRX+ receiver UI
- Automatically follows the currently tuned receiver frequency
- Live schedule data provided by Shortwave.sbs
- Displays the matching station, broadcast time, schedule, language, target area and transmitter site when available
- Frequency changes automatically trigger a new schedule lookup
- Stale results are ignored if the receiver is retuned while a lookup is still in progress
- Compact schedule card positioned directly below Vadelma Watch for quick DX identification
- Opened from the dedicated SKED button in the receiver header
- Integrated into the VadelmaRX receiver family, including Vadelma RX III Experimental
Audio EQ
- Client-side Web Audio equalizer
- Flat – neutral reference audio
- Speech – improved speech presence
- Warm – relaxed program listening
- DX – enhanced intelligibility for weak signals
S-Meter
- Native HF S-unit scale
- S9 = −73 dBm reference
- Smoothed meter movement
- Fast peak indicator
- S9+ dB display
Vadelma Spectrum
- Expanded 120 px spectrum display
- Custom signal-level colour palette
- Enhanced filled spectrum with bright signal trace
- 10 dB reference grid with live dB scale
- Receiver passband overlay
- Live noise floor, signal level and SNR display
- Center-frequency reference line
- Strongest live signal marker with dB readout
- Optional spectrum peak-hold tracking with slow decay
- Peak Hold state remembered locally by the browser
- Implemented as a local OpenWebRX+ receiver plugin
- Visual styling coordinated with the VadelmaRX UI and analysis colour system
DX Status Bar
- Always-visible compact receiver and propagation overview
- Live geomagnetic Kp index from NOAA space weather data
- Live planetary A index for geomagnetic activity
- Current tuned-channel SNR shown directly in the status panel
- Colour-coded bar indicators for quick visual assessment
- Kp, A and SNR integrated alongside the native OpenWebRX+ status meters
- Designed as the lightweight overview layer, while Vadelma Watch provides deeper signal analysis when needed
Receiver Session Recovery
- Current receiver profile remembered locally in the browser
- Current tuned frequency remembered before an unexpected WebSocket disconnect
- Automatic profile restoration after WebSocket reconnection
- Tuned frequency restored after the correct receiver profile has reloaded
- Prevents reconnects from falling back to the default receiver profile