Producer’s statement
ChameleonSDR is commercial SDR software intended for receiving, demodulating and analysing radio signals with compatible SDR receivers. The program works as a passive receiver and does not transmit radio signals by itself.
ChameleonSDR supports, among other things, decoding of DMR and TETRA transmissions. The mere ability to decode these standards does not mean that protected communications can be accessed without the appropriate authorisation.
For cryptographically protected transmissions, ChameleonSDR is not intended for breaking, guessing, recovering or circumventing cryptographic keys. Where a function requires a cryptographic key, the key must be supplied by the user. The user is responsible for holding the appropriate authorisation to use that key and to receive, decode and process the transmission in question.
The program does not grant the user any additional rights to receive, decrypt, record, transcribe, translate, store or disseminate radio communications. A user of ChameleonSDR must comply with the law in force in the country in which the program is used, in particular the rules on the confidentiality of electronic communications, the protection of personal data, the use of radio frequencies and access to information.
ChameleonSDR is a general-purpose software tool. The producer does not encourage obtaining unauthorised access to communications or circumventing cryptographic protection. The program's functions may be used, among other things, for hobby, technical, research and educational purposes and for professional analysis of radio signals, in accordance with applicable law.
The user bears responsibility for the way the program is used and for the lawfulness of the communications received and processed.
ChameleonSDR is not a tool for breaking cryptographic protection and neither guarantees nor claims access to communications for which the user does not hold the appropriate authorisation.
Notice to IP Holders, ETSI & Regulatory Bodies
We respect intellectual property rights. The software was architected from the ground up with compliance with international copyright and patent law in mind, and this page describes the design decisions that serve that goal. It sets out our position on the TETRA standard, patents and ETSI copyrights, and is not legal advice.
1. Where the code comes from, and copyright
- No ETSI code. The TETRA protocol stack and the ACELP decoder were written from the published description of the standard. The program does not contain, embed or distribute ETSI reference source code.
- Not everything is written from scratch, and that is said plainly. The TETRA and CW decoders and the SGP4 orbit model come from published specifications. The DMR privacy handling is a port from ISC-licensed code (DSD-FME), the Message Indicator expansion uses an MIT-licensed LFSR implementation, and the map symbol geometry comes from an MIT-licensed library (milsymbol). Each of those is listed below with its licence and its copyright holder.
- BYOF Architecture (Bring Your Own File). We do not distribute copyrighted Vector Quantization (VQ) tables or proprietary constants. Where certain decoding features require these files, users must source them independently, accept ETSI’s terms, and manually load them into the software. The executable remains free of ETSI copyrighted assets.
2. Expired Baseline Patents & Passive Reception
- Expired Core Technology. The software implements fundamental TETRA air-interface and baseline ACELP speech-coding protocols standardised between 1995 and 2000. As international patents have a maximum 20-year term, the foundational patents essential to these legacy specifications have expired.
- Passive Receiver Exemption. This software operates strictly as a passive, RX-only listener. It does not transmit, broadcast, or interact with network infrastructure.
3. Software Dependencies & Cryptography
- A decoding engine and nothing more. Chameleon SDR contains only a decoding engine. It has no ability to break, guess or bypass encryption keys. Playing back the audio requires the correct key to be entered by hand by the user.
- Strictly permissive licensing. The software is built without copyleft (GPL) code. Third-party dependencies use permissive licences such as Apache-2.0, MIT, ISC, BSD, zlib, Unlicense and CC0; the fonts use the SIL Open Font License and the sounds Creative Commons licences. The only GPL-licensed code is the GCC compiler’s runtime libraries inside voacap.dll, covered by the GCC Runtime Library Exception, which permits distributing the compiled program under any terms.
- On-device AI, no cloud. Speech transcription (Whisper, MIT) and translation (OPUS-MT via CTranslate2) run entirely on the user’s machine. No audio, transcript or translation is uploaded. NLLB-200 is deliberately not used because its licence is non-commercial.
- Where the offer applies. The program is offered only to customers in European Union countries; no sales are made outside the Union. Orders placed from outside it are refused, and that is stated in §1 of the shop terms.
- Export controls. Cryptographic components are provided for lawful, authorised analysis only. Within the Union the end user remains responsible for complying with the rules of their own country.
4. Trademark Nominative Fair Use
- “TETRA” is a registered trademark of the European Telecommunications Standards Institute (ETSI).
- Its use is limited to nominative fair use to accurately describe technical compatibility and interoperability.
- This product is independent and is not affiliated with, sponsored by, endorsed by, or certified by ETSI or the TETRA and Critical Communications Association (TCCA).
Third-Party Legal Notes & Licences
Chameleon SDR is proprietary software. It contains third-party components under permissive licences that permit their use in a closed-source product when the required notices are provided. The full notices, including the complete Apache 2.0, BSD, zlib and SIL Open Font License texts, ship inside the program and are written out to the data folder at every start as THIRD-PARTY-NOTICES.txt. This page is the summary; that file is the full text.
Integrated components (permissive licences)
- mbelib (AMBE/IMBE speech synthesis). Used by the DMR decoder. Copyright (C) 2010 mbelib Author; distributed under the ISC licence, as is, without implied warranties or liability for damages. The DVSI patents at the core of AMBE+2 that were in force in the European Union have expired: US8315860B2 on 13 November 2022, US7970606B2 on 8 September 2025 and US7634399B2 on 7 November 2025. Outside the Union the picture is not the same: US 8,359,197 from the same family remains in force in the United States. It does not bear on this product, because the offer is limited to the European Union, but saying flatly that the patents have expired would be inaccurate without that sentence. “AMBE” and “AMBE+2” remain DVSI trademarks and are used here descriptively only; this product is independent of DVSI and is neither affiliated with nor endorsed by it.
- tiny-AES-c (AES-128/256 block cipher). A copy sits in the source tree but is not compiled into the shipped program: the AES used for DMR decryption was written here from FIPS-197. The notice is kept because the copy exists. Released to the public domain under the Unlicense, without conditions or warranties.
- DMR privacy handling, ported from DSD-FME. Copyright (C) 2010 DSD Author, ISC licence. From the ISC part of that tree come the Message Indicator expansions, the late-entry assembly and the per-frame keystream rules. No Basic Privacy key table is part of the program: that table was removed, and every key is entered by the user. The block ciphers themselves were written here from FIPS-197 and FIPS 46-3. No copyleft file of that tree is used.
- LFSR (Message Indicator generator). Copyright (c) mattames, MIT licence, https://github.com/mattames/LFSR. A maximal-length 64-bit linear feedback shift register after TIA.102-AAAD-A, used when expanding the Message Indicator.
- TEA1 / TEA2 / TEA3 keystream generators. Support the optional TETRA radio interface. Copyright 2023 Midnight Blue; licensed under Apache License 2.0. ETSI identifies TEA algorithms as restricted; compilation and use depend on the operator’s regulatory and business decision.
- Whisper (speech transcription, model + code). OpenAI’s Whisper code and weights are MIT-licensed, which is what allows the base model to be embedded in the product. whisper.cpp / ggml is MIT.
- OPUS-MT translation models (Helsinki-NLP). Apache-2.0, run by CTranslate2 (MIT, Systran) with SentencePiece (Apache-2.0, Google) and the Ruy backend (Apache-2.0, Google) in place of the proprietary Intel MKL. Embedded and loaded from memory. Modification notice as Apache-2.0 requires: the packs are converted from the Marian format into the CTranslate2 format and quantised to 8-bit integers. That changes the file layout and the numerical precision, nothing else; no retraining or fine-tuning was done.
- milsymbol (MIL-STD-2525 and APP-6 symbol geometry). Copyright (c) 2017 Mans Beckman, www.spatialillusions.com, MIT licence. Used are the shapes themselves, converted once into tables of coordinates, and the tables saying which pieces make up each symbol. The library is not used: it renders through a browser, and this program carries no JavaScript.
- Godot Engine (the 2.0 look). The 2.0 look (Chameleon SDR.exe) is the official Godot Engine 4.7.2 export template running the program’s own project; reception, the decoders and everything else run in csdr_core.dll. Copyright (c) 2014-present Godot Engine contributors, (c) 2007-2014 Juan Linietsky, Ariel Manzur; MIT licence. The engine contains components of its own (FreeType, HarfBuzz, ICU, mbedTLS, zlib, libpng and others) under permissive licences; their complete list with licence texts is the file
licenses\Godot-Engine-LICENSE.txt installed beside the program. The godot-cpp C++ bindings: Copyright (c) 2017-present Godot Engine contributors, MIT licence. - IBM Plex fonts (the 2.0 look). IBM Plex Sans, IBM Plex Sans Condensed and IBM Plex Mono, embedded unmodified. Copyright (c) 2017 IBM Corp. with Reserved Font Name “Plex”; SIL Open Font License 1.1 (the file
licenses\IBM-Plex-OFL.txt). The licence allows the fonts to be embedded in software that is sold, as long as they are not sold on their own. - VOACAP (the HF forecast on the Propagation page). HF forecasts are computed by VOACAP, the Voice of America Coverage Analysis Program, developed by an agency of the U.S. Government (NTIA/ITS), in J. A. Watson’s portable Fortran version (voacapl, https://github.com/jawatson/voacapl), built as
voacap.dll. According to the NTIA/ITS notice the software is not subject to copyright protection in the U.S. and may be used for any purpose; no warranty is given by NTIA/ITS or the U.S. Government, and distribution implies no endorsement by them. J. A. Watson’s modifications are released under CC0 1.0 (public domain). Two GPL utilities of the package (dst2csv, dst2ascii) are not built or shipped. The full notice ships beside the program as voacap\LICENSE.txt. - Sounds (the startup chime and the end-of-transmission beeps). From Freesound, under CC0, CC BY 3.0 and CC BY 4.0, unmodified. The author of each sound and a link to it are listed in THIRD-PARTY-NOTICES.txt.
Dynamically loaded components (not bundled)
- SoapySDR (SDR runtime). Used to communicate with the LimeSDR and with radios outside the list the program handles itself. The RTL-SDR, SDRplay, HackRF, Airspy, ADALM-PLUTO and bladeRF are driven directly, through their vendors’ own libraries. SoapySDR uses the Boost Software License 1.0. Chameleon SDR dynamically loads
SoapySDR.dll at runtime and does not distribute that library or its modules; installation is the user’s responsibility.
Outside services the program contacts
- Map tiles. There are twenty-one sources. Each is either one you sign up for yourself (MapTiler, Stadia Maps, Thunderforest, Azure Maps, Mapbox, Geoapify or your own tile server) or a U.S. Geological Survey service, which is a work of the US government in the public domain. Two of the USGS sources need no key at all, and they cover the United States only. The program stores the key and nothing else, redistributes no tile, and asks no map server for anything until online tiles are switched on. No volunteer community tile server is offered, because those servers ask not to be used this way.
- Map data. The commercial sources render from OpenStreetMap data, © OpenStreetMap contributors, under the Open Database Licence 1.0. The attribution that licence requires is drawn in the corner of every view and on every exported picture, next to the provider’s own. It must not be removed or covered up.
- Address search. Goes to OpenStreetMap’s Nominatim, and only when you type something that is not a coordinate and press Find. What crosses the wire is the typed text and nothing else: no position, no identifier, no list of what has been heard.
- Orbital elements. From CelesTrak, which redistributes orbit determinations made from US government tracking data, not subject to copyright. Nothing is fetched unless you press the button, or unless you turn on the daily automatic update, which is off by default. Only short lists are requested, and a repeat is refused for two hours.
- NOAA data (the Propagation page, 2.0 look). Space weather comes from the NOAA Space Weather Prediction Center (services.swpc.noaa.gov): the 10.7 cm solar flux and its prediction, the planetary K index and its forecast, GOES X-ray flares, the solar wind, alerts and warnings, the NOAA scales, D-RAP absorption and the OVATION aurora forecast. The tropospheric forecast on the VHF / UHF tab uses NOAA NCEP’s GFS model, through the NOMADS grib filter (nomads.ncep.noaa.gov). These are works of the U.S. Government, in the public domain in the U.S.; the source is credited (“Data: NOAA SWPC”) and their use implies no endorsement by NOAA or the U.S. Government. SILSO sunspot numbers (CC BY-NC) are not used: the program derives an effective sunspot number from the 10.7 cm flux (the ITU-R P.371 relation). When the program contacts NOAA and what it sends is described in the privacy policy (section 8); every NOAA download is turned off by the “Fetch NOAA space weather” switch on the Station tab.
- Licence activation. Activation goes to our own licence server (license.c-sdr.pl, run on Cloudflare) in one HTTPS call written here; no third-party code is involved. Sent are the licence key, the program's version number and a machine code, which is a one-way hash of the computer name and the system volume serial number and cannot be turned back into either. The check repeats by itself at start-up, once seven days have passed since the previous one, and sends the same again.
- Files fetched on demand. A larger speech model and extra translation packs come from Hugging Face; receiver drivers come from GitHub (RTL-SDR Blog, Nuand, Analog Devices) and from the Zadig site. None of it is fetched until you press the button for it, we host none of those files, and you download them on their publishers’ terms.
- A demo key from inside the program. A trial key can be requested from the program itself. Only the machine code goes to our server, with no e-mail address, so that one computer receives one trial key.
Excluded copyleft components
- librtlsdr. This GPL-2.0 component is deliberately not distributed with Chameleon SDR. RTL-SDR devices are accessed through an
rtlsdr.dll provided independently by the end user.
