Turn a cheap RTL2832U USB stick into a complete terrestrial TV receiver and FM radio with full RDS on any Android TV box or phone (USB OTG). No root, no kernel drivers — everything runs in userspace.
The FM panel: vintage dot-matrix display with live RT+ now-playing metadata (song title & artist), 8-character PS frame display, stereo blend indicator and signal bargraphs — decoded from plain FM broadcast by a $15 dongle.
- Full channel scan (PAT/PMT/SDT/NIT) with real LCNs, ISO-8859-7 names
- Hardware-accelerated playback via libVLC (MediaCodec), 1080i tested
- EPG (EIT now/next + schedule browsing), subtitles toggle, channel zapping
- Radio services included in the channel list (audio + now-playing metadata)
- Wideband FM with the proven rtl_fm recipe (high-rate capture, fs/4 offset tuning to dodge the zero-IF DC spike, 171 kHz MPX — 3×57k, integer RDS math)
- Stereo with signal-driven blend — modeled on classic car-radio chips (Philips TDA1591 SNC, Sanyo LA1888NM): gradual mono↔stereo transition driven by RSSI with asymmetric dynamics (fast to mono on signal drops, slow back), so weak stations never turn into a hiss bath. To our knowledge no other open-source SDR implements blend.
- Full RDS decoder, built from the standards and vintage chip datasheets:
- Carrier recovery: fixed 57 kHz mix → narrow LPF → Costas loop with gear-shifted bandwidth, FFT-based frequency acquisition (Hann, quality gate)
- Carrier-slaved symbol clock (encoder derives bit clock from the same oscillator — so do we)
- Block layer per SAA6588 receiver-chip practice: flywheel sync hold, any-pair sync, ±1 bit-slip recovery, burst-error FEC with per-block correction classes (text only from lightly-corrected blocks)
- PS as an 8-char frame display per NRSC-G300 (no reassembly heuristics), confirm-or-timeout publishing with chimera protection, RadioText with cumulative assembly and A/B-flag framing, CT clock (error-free groups only)
- RT+ (RadioText Plus): ODA 3A registration (AID 0x4BD7) → tagged song Title/Artist on their own quasi-static lines — the "MP3-player feel" found in BMW/Toyota head units
- AFC: acquire→lock FSM modeled on SDRangel's frequency tracker — hardware micro-retune for coarse acquisition, then a digital NCO smoothly follows the transmitter (drifting analog exciters included), zero audio glitches
- Per-tuner RF gain in real dB (R820T/FC0012/E4K/FC0013 tables), remote-key gain stepping, manual gain by design (the R820T hardware AGC pumps and splatters on FM — measured, not guessed)
- Dual-stick support with functional role detection: on startup the app probes which stick locks DVB-T — that one has the TV antenna, the other gets FM. Identity follows the antenna, survives replugging, self-heals.
- Vintage dot-matrix UI: amber display windows, red STEREO / green mono lamp, signal bargraphs
- RTL2832U USB stick (RTL-SDR). Tested: R820T (recommended) and FC0012 tuners
- Android 7.0+ device with USB OTG / USB host (TV boxes work great)
- For simultaneous-style TV/FM switching with two sticks: a powered OTG hub
Note: DVB-T demodulation runs in the RTL2832's hardware (as designed); FM is true SDR — raw I/Q via rtl_tcp, all demodulation in Kotlin on the device (~1 core of a low-end TV box for FM + stereo + RDS).
- Download the latest
dvb-fm-android-*.apkfrom Releases - On the Android device allow Install from unknown sources (Settings → Security, or per-app prompt on Android 8+)
- Install the APK — via file manager / USB stick, or from a PC:
adb install dvb-fm-android-v1.0.apk - Plug the RTL2832U stick into the USB OTG port (TV boxes: any USB port, ideally a powered hub) and open Επίγεια TV
- Grant the USB permission when Android asks
- TV: run a channel scan from the channel list (first start).
FM: press the FM button, tune with ◀ ▶ / ▲ ▼ or type the frequency
with the digit keys (e.g.
984→ 98.4 MHz)
The APK is debug-signed (hobby project) — Play Protect may warn on first install; that is expected for any sideloaded debug build.
- JDK 17, Android SDK 34, NDK 26.1, CMake 3.22 (native usbxfer + librtlsdr)
- Set
JAVA_HOME(ororg.gradle.java.homeingradle.properties), putsdk.dirinlocal.properties ./gradlew :app:assembleDebug
| Key | TV mode | FM mode |
|---|---|---|
| ◀ ▶ | — | tune ±0.1 MHz |
| ▲ ▼ | zap channel | tune ±1.0 MHz |
| CH± | zap channel | RF gain ± |
| OK | info banner / EPG | — |
| MENU | subtitles | RF gain + |
| digits | channel number | frequency (e.g. 984 → 98.4) |
| Back | list / exit | back to TV |
The FM side uses a raw hub design borrowed from car-radio IC block diagrams: one owner of the device produces a single raw MPX ring buffer; audio (stereo decoder) and RDS are independent subscribers with their own filters and threads. A slow consumer drops its own samples and can never stall the producer — the stereo path structurally cannot degrade RDS.
Comments in the source are currently in Greek (the project grew up bilingual); translations are welcome — the code itself tells the story in plain Kotlin.
- signalwareltd/AndroidDvbDriver — userspace DVB driver (GPLv2)
- martinmarinov/rtl_tcp_andro- — rtl_tcp for Android (GPLv2)
- rtl-sdr-blog/rtl-sdr-blog — modern librtlsdr (GPLv2)
- VideoLAN libVLC — playback
- f4exb/sdrangel — the FLL that inspired our AFC
- windytan/redsea — reference RDS decoder used as test oracle
- Standards & datasheets studied page by page: EN 50067 / IEC 62106, NRSC-G300, Silicon Labs AN243, EBU tech review 307 (RT+), and the glorious service manuals of the Philips SAA6588, TDA1591 and Sanyo LA1888NM
GPL-2.0 — same as the vendored drivers this project stands on. See LICENSE.
Use a legal antenna setup and respect your local broadcast regulations. Built with love, measurement instruments, and a pair of magic eye tubes. 📻