hydrasdr_433 ISM Decoder, Android Support & SDR++ Nightly Builds
Three new open-source releases are now available for the HydraSDR RFOne
software defined radio:
hydrasdr_433, a wideband ISM band decoder supporting 290+ wireless protocols;
libhydrasdr v1.1.1 with native Android support; and
updated SDR++ nightly builds for desktop and mobile.
Pre-built packages are available for Windows, macOS, Linux, and Android.
hydrasdr_433: Wideband ISM Band Decoder for HydraSDR RFOne
hydrasdr_433 is a wideband ISM data receiver built specifically for
HydraSDR hardware. Based on the widely-used
rtl_433 project,
it adds native CF32 support, a polyphase filter bank channelizer, and host-accelerated
signal processing that take full advantage of the RFOne’s 10 MHz bandwidth and 12-bit ADC.
hydrasdr_433 decodes 290+ protocols
(full list)
across the 433.92 MHz, 868 MHz, 315 MHz, 345 MHz, and 915 MHz
ISM bands. Supported devices include weather stations, tire-pressure monitors (TPMS),
door/window sensors, remote controls, energy meters, and hundreds of other wireless
devices used in home automation and industrial monitoring.
hydrasdr_433 self-hosted web UI embedded directly in the binary.
No external CDN, no Google Fonts, no internet connection required, the entire UI loads from memory in under 50 ms.
Wideband Scanning Mode
Unlike traditional single-frequency capture, hydrasdr_433 can monitor an
entire ISM band simultaneously.
The -B option splits the RF spectrum into parallel narrowband channels,
each decoded independently:
# EU 433 MHz ISM band — 8 channels over 2 MHz
hydrasdr_433 -B 433.92M:2M:8
# US 915 MHz ISM band — 16 channels over 8 MHz
hydrasdr_433 -B 915M:8M:16
# EU 868 MHz SRD band — auto 1 MSps covers the full 600 kHz band
hydrasdr_433 -f 868.5MThis wideband approach captures every sensor transmission across the full ISM band
with a single HydraSDR RFOne, instead of tuning to one frequency at a time.
Polyphase Filter Bank Channelizer
Wideband mode is powered by a 2× oversampled analysis polyphase filter bank
(OS-PFB) designed for high channel isolation with minimal processing overhead.
| Taps per branch | 48 |
|---|---|
| Window function | Kaiser, 80 dB stopband attenuation |
| Adjacent channel rejection | > 41 dB |
| Passband ripple | < 0.1 dB within 90% of channel spacing |
| Oversampling | 2× — preserves signals at channel edges |
Runtime CPU SIMD Dispatch
A single binary automatically selects the best instruction set at startup — no
recompilation required:
| Architecture | Instruction Sets |
|---|---|
| x86-64 | SSE2 (baseline), AVX2+FMA, AVX-512 |
| AArch64 | NEON (baseline), SVE (Linux) |
On an AMD Ryzen 9 7950X3D with AVX-512, the channelizer reaches
85 MSps throughput — a 33× real-time margin at 2.5 MSps input.
This leaves plenty of headroom for all 290+ protocol decoders to run in parallel.
Native CF32 Pipeline
The HydraSDR RFOne delivers samples as complex float32 (CF32) natively.
hydrasdr_433 processes CF32 end-to-end without format conversion, providing higher dynamic
range than the CU8/CS16 paths used by RTL-SDR.
Polyphase Resampler
A per-channel polyphase resampler converts from the channelizer output rate
to each decoder’s expected sample rate, ensuring every protocol decoder receives samples at
the exact rate it was designed for.
| Taps per branch | 32 |
|---|---|
| Window function | Kaiser, 60 dB design stopband |
| Measured stopband | 74–76 dB |
| Rate conversion | GCD-based L/M ratio reduction for minimal computation |
| Bypass mode | Automatically engaged when channelizer output already matches decoder rate |
Cross-Channel Deduplication
A cross-channel deduplication filter (FNV-1a hash, 500 ms window)
suppresses duplicate decodes from overlapping channels while preserving legitimate
retransmissions on the same frequency.
Download hydrasdr_433
Pre-built packages for
Windows x64, macOS (ARM64 & x86_64), Ubuntu, Debian, Linux Mint,
Fedora, AlmaLinux, openSUSE, Arch Linux, and ARM64 (Raspberry Pi).
Download nightly build →
Source code & documentation on GitHub
libhydrasdr v1.1.1: Host Library with Android Support
The core HydraSDR host library has been updated to v1.1.1. The headline
addition is Android support, enabling mobile SDR applications to use
HydraSDR RFOne hardware via USB OTG — just a USB-C to USB-C cable for power and data,
no adapter needed. This builds on the
v1.1.0 release
that introduced the Hardware Abstraction Layer, DDC decimation, and lock-free streaming.
What’s New in v1.1.1
| Android support | Build and run on Android devices; connect the RFOne via USB OTG for portable SDR |
|---|---|
| API documentation | Full Doxygen-generated HTML & PDF with interactive call graphs and source browsing |
| DDC benchmarks | Automated CI benchmarks across all platforms for continuous performance tracking |
| Platform coverage | Native .deb, .rpm, and .pkg.tar.zst packages for 15+ GNU/Linux distributions including ARM64 (Raspberry Pi 3/4/5) |
Download libhydrasdr v1.1.1
Pre-built packages for
Windows x64, macOS (ARM64 & x86_64), Android,
Ubuntu, Debian, Linux Mint, Fedora, AlmaLinux, openSUSE, and Arch Linux
— including ARM64 for Raspberry Pi.
Download nightly build →
Source code & build instructions on GitHub
SDR++ for HydraSDR: Desktop and Android Builds
The HydraSDR fork of SDR++,
the popular cross-platform SDR application, ships with a native HydraSDR RFOne source module. This nightly build provides a full spectrum analyzer and receiver
with waterfall display, multiple demodulation modes, and recording capabilities on
Windows, macOS, Linux, and Android.
Available Builds
| Platform | Package |
|---|---|
| Windows x64 | sdrpp_windows_x64.zip |
| macOS ARM64 (Apple Silicon) | sdrpp_macos_arm.zip |
| macOS x86_64 (Intel) | sdrpp_macos_intel.zip |
| Android | sdrpp.apk |
| Ubuntu 24.04 / 22.04 / 20.04 | .deb |
| Debian Sid / 12 / 11 | .deb |
Setup Notes
Linux & macOS: If “HydraSDR RFOne” does not appear in the source list,
open the SDR++ Module Manager, locate hydrasdr_rfone_source, and add it with
the name “HydraSDR Source”. Windows and Android installations include it automatically.
Important: On Linux and macOS,
libhydrasdr must be installed before the
HydraSDR source module will appear. See the
troubleshooting page if you need
help with setup.
Download SDR++ for HydraSDR
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