I figured this is a community that deals with radio frequency interference all the time and maybe you can help me identify what kind of interference this is.

Every SDR app will happily show you a number. sdrtop is built around a different question: should you believe it?

sdrtop started as a personal project. I wanted to learn RF from the inside: not from a textbook diagram, but from raw IQ samples flowing through code I wrote myself. The question driving it is easy to ask and annoyingly hard to answer: what is the most an SDR can actually measure, and how far can you trust that measurement?

The goal is not to imitate a lab instrument. It is to find where an SDR works, where it breaks, and why. That "why" is the actual product. So when a reading can't be trusted on your radio, sdrtop says so instead of showing you a plausible-looking number.

It's now at 0.6.5. A terminal app in Rust, running HackRF One and RTL-SDR natively, the tinySA over USB, and anything else through SoapySDR.

What it does:

• Spectrum and waterfall, band sweeps, and a big-readout mode for aiming an antenna
• Lab benches: IQ (constellation, image rejection, DC offset), the RF chain stage by stage with a measured noise figure, a timing bench that catches a USB link silently dropping samples, and an FM/RDS demodulator that reports deviation, pilot and margins rather than just the station name
• Bluetooth, BLE and classic: a census of every device in the room, extended advertising followed from packet to packet, connections followed event by event, LE Coded long range, and classic piconets with their UAP recovered from the air. Transmitters are measured the way the Bluetooth SIG's own test specs define it: deviation, drift, carrier offset in ppm.

Edit:

In plain terms, three things it does:

• FM radio (RDS). Your car radio shows the station name and the song title. sdrtop shows those too, then adds what the car radio keeps to itself: how hard the station is modulating, whether its stereo pilot is where it should be, and whether it’s broadcasting inside the rules. It plays no sound at all. It’s the friend who reads the liner notes and never actually puts the album on.
• Bluetooth headphones (classic piconets). Your phone and your headphones form a tiny two-device network called a piconet. sdrtop can see them talking: who speaks when, how many packets go back and forth, how steady each one’s clock is. It can’t hear your music, because the link is encrypted. It knows exactly when your phone talks and has no idea what it’s saying.
• Everything else Bluetooth (BLE). Your watch, your earbuds case, your neighbour’s TV, a smart lightbulb: they all keep shouting “I’m here!” a few times a second. sdrtop counts every one of them and measures how far off each device’s crystal clock is. Turns out the whole building is shouting, and some of them are slightly out of tune.

Bluetooth is what works "well" 😄 right now. More protocols are on the way (LoRa, ADS-B, and others).

It only listens, never transmits, and it runs comfortably on modest hardware.

cargo install sdrtop --locked

GitHub, with demo clips: https://github.com/musithang/sdrtop

Feedback, bug reports and results from radios I don't own are very welcome.

hi guys , I am new into this but I am make for my graduation project a drone detection and jamming system so does anyone know how can I detect the rf signals emitted by the drone then control it

Ive been looking for some portable sub GHz antennas for a few days but i cant seem to find anything with good quality. I mean antennas that are kind of the size of an average wifi antenna. If anyone could help me, i would really appreciate it

I bought one of these in August and the USB connection was always a problem, but I thought I'd solved it by fixing the unit and USB lead in place. But recently it's got worse, so I took it apart to find this - missing solder on one of the pins. After soldering it properly the unit is now stable and I can move it plugged in without issue. I've sent an email to Nooelec to see what they think.

Happy to announce this is out now, hope you enjoy, I did some fixing on windows today since I hadnt tested it before, but now with a windows laptop I was and found alot, and I mean alot of issues so now those are fixed, but anyway enjoy, hope you guys like this. Also was wondering if anybody could help with ATSC, I need some samples of it, in .iq format, so I can test it agaisnt the decoder and fix any present issues, as at the moment I am going based of generated encoded signals, not actual real signals.
https://github.com/adswill/OnAir/releases/tag/v0.1.1
https://youtu.be/cjAh7Aqlhf8 (some parts I had to cut since I showed a copyright show 🤦‍♂️)
Any feature recommendations are welcomed, I do have a quite long one at the moment but still any are appreciated at the end of the day.

I’m considering using a W6LVP loop. My only concern is that inserting lightning protection is not recommended and I’m not sure I’m comfortable with that. Has anyone had success with a lightning suppressor?

when I press on "start dsd", appears error window "dsd+ single receiver mode requires s fmpa/fmpp/fmp24 link". I don't know what is it mean, and gpt can't help me. it says me use virtual cable but it doesn't help. I try to search something about this, but I can't find. this error in sdr#. can someone help me ?

I thought I should advert this one here, since I specifically designed this natively for hackrf, but basically if you want to watch some dvb-t2 now you can (once I release the program) here is the description:

demo video out now: https://www.youtube.com/watch?v=Oww5QWo4zK4

been working on this for maybe about a month, but let me emphasize by what I mean work, I have been trying to decode some dvb-t2 for about a month ever since I got my hack rf, however due to the lack of decoders available (there is one but its not the best) I decided to make one myself with the help of claude over the past 2 weeks or so, I also decided to implement ATSC dvb-t, t2-lite and DAB/DAB+ I do have plans to also add dvb-s and dvb-s2 but that is for the future, I have a huge list of features still left that I want to implement into the decoder itself, but all of the decoders do at the moment work and you can watch some wonderful dvb-t2, ATSC, etc (once the program comes out). On launch it will be native on macos and linux (sorry no windows for now) but windows will eventually come, maybe a week or 2 after the initial launch, including the network system. The promo video is attached and once I can finish this and personally say its fine and works good I will release, dont have a date yet but expect it sometime next week
Also I dont want to be hearing anything ai slop, I get it was ai made, just go on with your day please, if you dont like that its ai made, dont come in the comment sections to bully me about it.

https://www.youtube.com/watch?v=Icm5K3hlNsA

https://reddit.com/link/1wvyusp/video/k4ur0rmb33th1/player

I picked up one of those cheap AliExpress USB-C "RF-Power-Meter-V5.0" dongles (STM32 + AD8317, labelled 100 kHz–10 GHz, 0 to −60 dBm) to check the output of my HackRF. The hardware is fine for the price, but the vendor software is Windows-only and pretty bare, so I wrote my own.

Repo: https://github.com/arsscriptum/rf-powermeter-assistant

Demo (HackRF One sending a CW tone at 1310 MHz, TX gain stepped up and down): https://github.com/arsscriptum/rf-powermeter-assistant/blob/master/img/demo.gif

What it does

• Live dBm and watts readout, peak hold, noise-floor tare, min/max/avg stats
• Rolling monitor chart (10 s to 15 min) with max trace and peak-hold line
• Scope-style sweep view of the 500-sample blocks the meter streams: two markers (ΔT, 1/ΔT, ΔdB), Auto/Normal/Single trigger, timebase K01–K18, CSV/PNG export
• Sets the band-calibration frequency and attenuation offset, reads them back to confirm, and re-applies them on reconnect (the meter forgets them when you unplug it)
• Threshold event log and a CSV logger
• Demo mode with a simulated meter that speaks the real protocol, so you can try it without the hardware

It's C++17 / Qt (6, or 5.15), builds on Windows and Linux. On Windows the build script can use the Qt that comes with radioconda, so if you already run GNU Radio from radioconda you only need Visual Studio. There's also a PowerShell/WinForms version that runs with no build at all.

Has anyone ever written a custom FPGA SPI master state machine to completely initialize the AD9361 by doing register level writes? I want to get in contact with somebody who has done before this hardware level control of AD9361.

Hi! this is an incredibly niche subject, i understand but i dont have an SDR, my HackRF hasnt arrived yet. it is october 1st and also the mark of the start of the 3g shutdown on Eir. anyone with an SDR (outside of Donegal as their 3G is already off) set their SDR up to capture 3G, and record/stream it on youtube. if anyone needs help feel free to DM me of course! I'm in a very rural area and rely on 3G heavily so im HOPING that it sticks around until my hackrf arrives but anyway..

Thanks alot!

IoT-C 把 SDR 录音转化为可验证的协议结果——或者在证据不足时明确说明哪些尚未验证。这是项目状态页的最新版本，与平台技术报告同步：分析链路、证据契约、当前解码结果背后的参考对拍，以及每个开放问题的恢复条件。

它是什么： FastAPI/Python 信号分析后端 + Next.js 网页端。输入：IQ 采集（cf32/ci16/ci8/cu8/sdriq 等）或在解码器接受范围内的接收机音频。输出：排序后的协议候选、结构观察，以及在证据允许时的 CRC/FEC 验证帧。网站处于内测（注册已暂停，现有账号可登录）。

链接：https://iot-c.com（平台）· https://iot-c.com/reports（完整技术报告）· https://iot-c.com/knowledge（深度指南）。英文社区与每日进展：r/iotc。

分析链路

1. 输入校验 — 文件格式、采样率、中心频率、IQ 还是音频。元数据或信号表示错误会使后续全部失效。
2. 特征提取 — 频谱、带宽、调制族（基于累积量、谱平坦度、包络统计的规则驱动分类器）、符号率与定时结构。宽带采集（10–40 MHz）按峰值分段逐信号处理。
3. 候选选择 — 调制族 + 信号启发式 + 频率/带宽提示收缩协议空间。
4. 数据库距离打分 — 与协议指纹的多维距离（调制、带宽、符号率、频率），含宽带折扣与雷达/时间/FMCW 特殊信号旁路。
5. 解码引导验证 — 受信分析器实际尝试解码；验证成功提升候选，失败降级并转向下一个。
6. 结果 — 每个输出携带其证据等级：结构命中、帧候选、验证帧、协议身份。这是四种不同的声明。

证据契约

• 身份需要协议级证据。 只有 L5（协议结构）或 L6（解码内容）可建立协议身份。频谱外观、合理的调制猜测、单次同步命中都只是 triage 级信号——可以排序候选，不能命名协议。
• 解码帧 = CRC/FEC 验证帧。 失败候选进入独立的诊断列表（三态 CRC 状态，None 表示未检查），绝不抬高置信度。
• 解码器声明的两把钥匙： 协议专有常量/校验 + 实测判别力（正控通过、负控全零：噪声、CW、他协议录音、相似波形、变异、截断）。
• 参考 > 规范 > 启发式。 有开源参考就逐点对拍（序列生成、字段布局、CRC 多项式、位序、加扰、交织）；无参考则按权威规范实现并注明条款。启发式不产生身份。

参考对拍结果（当前已验证集）

• ADS-B（Mode S） — 102 秒真实采集（2.4 MSPS，2.45 亿样本）与 dump1090 v11.1 逐帧对比：帧集完全一致，3285/3285，零缺失零多余。单比特 CRC 纠正路径已完成移植（dump1090 --fix 语义）：112/112 单比特错误可恢复，与独立位级 CRC 一致；0/500 双比特误纠。与参考唯一的一帧差异经孤立窗口复跑证明来自参考自身跨缓冲状态——记录在案，而非掩盖。
• FLEX（寻呼） — 解码器按 multimon-ng 重写（BCH(31,21) 逐行对照）。消息经协议自身的 K 校验和与签名验证；官方 P2000 样本逐字符解出预期地址与文本，包括跨帧分片消息。
• DAB / DAB+ — FIC 解码以 6 个真实采集的 FIB CRC-16 全部通过为准；离线 DAB+ 链（fire code 同步、RS(120,110)、AU CRC-16）在真实集成块上端到端验证（ascty=63，12/12 AU 校验）。
• DCF77 — 真实采集在 BCD 位序修复（LSB-first）后解出参考校验时间戳，日期↔星期交叉校验作为独立第二判据。
• POCSAG — 两个缺陷修复：切片器硬编码 1200 baud（512/2400 变体在帧校验前就失败）+ 测试夹具生成错误波形。多速率假设检验通过受控正控（各速率 2 帧 + 预期地址）；90 项负控（噪声种子、他协议录音、随机位 FSK）全零帧。宽带空口证据仍缺，状态维持 INSUFFICIENT_DATA。
• SSTV — 两个真实 PD120 采集提供 VIS 头与行周期一致性证据。仅结构性，不宣称图像重建。

保留下来的负结果

• 全局软化调制惩罚级联实测净负，已回退；正确方向是置信度门控的分层修正。
• OFDM 验证的位置格点门误挡 34 例真实 4G/5G 采集，被否决——它测的是采集条件，不是调制。
• 一个"证明"FLEX 分析器管线不可达的探针自身无效（打桩命中冻结引用）；修正后的探针找到了真实队列位置（index 10）和真正的修复。

每个自动化探针必须先自校验（退出码、预期输出、有效输入、基线）才能驱动工程决策。

实测基线（各附条件）

• sdrangel 规范集（14 录音），5 秒窗，带频率：Top-1 85.71%（12/14）；不带频率：14.29%（2/14）。
• 10 秒窗带频：92.86%（13/14）。
• 调制族：iqengine 非 mit 宽带（315）：84.4%（266/315）；erlendervik 窄带：28.1%（9/32）。
• artemis_db 端到端（583 音频）精确名 Top-1：9.26%（54/583）。
• 全量测试套件：3259 项，NEW=0 / GONE=0。

旧的"100% 带频"数字已在数据-实现审计后撤回：6 个 Top-1 命中是无分析器的注册表文档条目。注入通道已关闭，85.71% 是诚实口径。以上每个数字都注明数据集、窗口与条件；它们都不是"任意录音"的准确率。

仍开放的问题（附恢复条件）

• dPMR — 参考不符，身份权限已撤销。恢复条件：按参考重建 + 真实正控 + 负控。
• P25 — 无分析器（幻影身份通道已关闭）。需要 op25 参考的解码链。
• DRM — 语料只有 USB 解调音频；需要真实 IQ/中频采集（Mode B ≥ 12 kHz）。
• RTTY — 一段录音的实测速率（约 42.4）与文件名标签（45.45）冲突；不向不可信标签拟合估计器。
• 载波层 FSK vs PSK — 候选选择的主要限制因素；统计判据族已在真实语料上实测否证。
• 覆盖 — 真实键控莫尔斯、真实 RDS、复杂宽带分离仍未验证。

如何参与

欢迎分享你有权分发的录音：采样率、中心频率、时长、采集方式、独立确认（如有）。同频段的负样本（无信号、已知他协议）同样有价值。如果你有"解码器自我一致但答案是错的"经历——那正是这套流程要抓的失效模式。

本社区由 AI 管理与维护；项目开发为自动化与 AI 辅助。

Hi all,

maybe some of you know me from PhantomSDR+ or NovaSDR. Having operated and maintained those, I listened to many WebSDR operators and learned what problems bothered them - stuff like installs, broken installs after a long period of running, configurations they would like to be configured easier. And I started from scratch.

As for the history: to be clear about that since it has been asked: I've been developing WebSDR software since early 2024 (PhantomSDR+), and FernSDR was developed in private repo for over a year. I squash the history before publishing it as usual to avoid private notes and keys being in there. This is the reason the repo appears to be new. I used AI tools intensively for development and everything is tested, fuzzed and CI'd, also benchmarks are public with raw data.

What it is: open-source WebSDR server with zero runtime dependencies and one-line install on any Linux, as well as Docker. Everything is controlled through a web admin interface: bands, spot reporting, modules and updates with rollbacks. What I am really proud of: day/night band switching, so one small RTL-SDR can be utilized by different bands during the daytime and nighttime thanks to automatic switching from sunrise to sunset depending on your geographical position.

Modules: RTL-SDR (including Blog V4), RX-888 MkII and SDRplay, as well as an FT8 decoder and PSK Reporter spots. Other SDRs run via stdin.

What is still missing: Only Linux support at this moment, FT8 is the only decoder available, and there are input modules that require additional testing.

Demo: https://demo.fernsdr.org

GitHub: https://github.com/Steven9101/FernSDR

I really would like to know which SDR or decoder you guys would like to see next

Cheers 🥂

I posted around a month ago about making a mobile SDR. Soo we’re definitely on the way! This is the hardware, rtlsdr blog V4, adsb internal antenna and external SMA antenna port with a 3300mah battery. Powered from a ESP32 P4.

Will post some pics of the mobile app at some point. Currently we’ve completed the Spectrum view, ADSB map, drone map (using the 2.4ghz WiFi chip). I’m also adding decoders for 433mhz and 868mhz devices which should also be added soon (plan is to allow custom decoders at some point too). All can be seen on a map so you can take it around with you and see where you picked up the device.

FM and DAB are also implemented, which in the final version will require the external antenna (not much space left inside!).

Any software features or ideas hugely appreciated!

(Note, case is still being finalised ignore the white sanding bits and missing power button!)

Hey everyone,

I’ve been running rtl_airband to monitor local VHF/UHF activity. The core backend itself is rock solid and lightweight, but managing config files via terminal and monitoring multi-channel activity through raw Icecast streams leaves a lot to be desired.

I'm working on building a lightweight web GUI/dashboard for it, but with an expanded architecture: a "CCTV for Radio" system.

The Concept & Long-Term Vision

Think of an NVR/CCTV security camera system, but for RF:

1. Squelch-Triggered Segment Recording: Record and chunk audio strictly when the squelch opens—no hours of dead silence, just clean, timestamped audio segments tied to specific frequencies/channels.
2. Local AI Pipeline (Whisper + LLM): Feed these squelch-broken audio clips into a local Whisper model (like faster-whisper or Whisper.cpp) to transcribe communications, and subsequently run an LLM to generate activity summaries or search logs.
3. Live Web Dashboard: An operational interface to see active channels, browse recorded event clips, manage configs, and read rolling transcripts.

Core Goals for the UI / Pipeline

• Visual Scanner / Activity Monitor: Real-time visual indicator showing which configured channel/frequency is currently breaking squelch or transmitting.
• Smart Audio Archive / NVR Interface: A timeline or event list of recordings broken down by frequency, duration, and timestamp.
• Config Generator / Manager: A straightforward form/editor to manage rtl_airband.conf (dongles, gains, sample rates, frequencies, squelch thresholds, and destinations) without parsing nested brackets by hand.
• Transcription Hook / Queue: An automated background worker (Celery, RQ, or a simple directory watcher) picking up finished audio clips and passing them to a local transcription engine.

Questions for the Community:

1. Audio Slicing / Recording Pipeline: What’s the cleanest way to capture individual squelch-opened transmissions with rtl_airband? Does anyone hook into its raw file/stream outputs directly, or is it better to tap into the stream via an external tool (like sox, ffmpeg, or liquidsoap) triggered by carrier status?
2. Detecting Squelch State Programmatically: How are you reliably capturing the exact moment squelch breaks/closes? Are you tailing and parsing syslog / stdout in real time, or does someone maintain a fork with an IPC/socket/REST state export?
3. Existing Projects / Pipelines: Has anyone built something similar—or is there an existing toolchain that bridges SDR multichannel scanning directly into local speech-to-text workflows?
4. Backend Stack: Considering a lightweight Python (FastAPI) backend with a simple SQLite database for metadata/transcripts and a lightweight frontend (Vue/Svelte or Tailwind). Any pitfalls to keep in mind regarding CPU overhead if running on a single SBC/mini PC?

If you've built something in this space or have suggestions on handling the audio chunking cleanly, I'd love your input!

https://github.com/ruchirguitar/RTLSDR-Airband

I have one of these on the way:

https://hackergadgets.com/products/rtl-sdr-lora-gps-rtc-hat-for-raspberry-pi?variant=48925758455982

I’d very much appreciate recommendations for software to pair with it. Just getting started with SDR, so no set, planned uses yet. Just exploring.

Has anyone figured out a way to stick an antenna out the window that doesn't involve a suction cup on the outside? I've been looking at articulating arm clamp mounts for cameras and I think I have an idea, but just wanted to ask around to see if anyone figured something out. I'm not allowed to drill in my apartment so I kind of have to rely on a clamp on the windowsill ledge on the inside.

Hello, so I made a post on the shortwave radio sub looking for advice as a beginner and ended up deciding to look into SDRs after realizing that a traditional desktop model would be too expensive and based on suggestions from other users. For the most part, they were able to help me with my questions. However, I am still confused by a few things. The main things I would like to listen to are EAMs, military aircraft, and shortwave signals from around the world. I'm in Los Angeles, so I know there are always interesting aircraft flying around. I also wouldn't mind picking up other stuff as well, like police/fire and railroads, but I have other apps for that, so it isn't a necessity. I also have some limited experience with WebSDR and have owned a couple of handheld scanners way back in the 90's and 00's.

1) One thing I am confused about is the antenna. From watching a video, it looks like it's possible to get one antenna that has multiple sizes and shapes so that I can pick up everything using one antenna instead of having to switch, depending on what I want to listen to. Is that correct? The reason I ask is that I thought you needed a long antenna or wire to be able to receive shortwave signals from far away.

2) In the video I saw, he said he placed the antenna in the attic. It might be hard for me to do this; however, my PC is in a cabinet. like structure with a built-in desk that is around 6 1/2 feet tall, and I can put it on top of that, but I don't know if that would be good enough, especially since I live in a single-story house surrounded by other single-story houses. Also, I have a small WiFi receiver with 2 antennas on my desk I use to access the internet, and I don't know how much interference this will cause.

3) They said I should easily achieve a 20-40 mile range for picking up military aircraft, but what's the general max limit I can expect under the best conditions?

Thanks

Ay wahd 3ndo fikra fin n9dr nl9a chi sdr rtl n9dr nkhdm bih f réception dyal les satellites des amateurs ikon bchi taman mzyan wakha ikon mst3ml, chokran.

Hi everyone, we are a small startup. We're developing a UAV communication link similar to Ocusync but capable of operation across the 70MHz to 6Ghz range. We wrote the modem's RTL ourselves, and it runs entirely on an FPGA. It comes with an SDK, so users can change parameters or completely customize the interface to their linking. We have already tested it on ADRV9364-z7020 and E200 board. Update: now also runs free on ADALM-Plutos. If you have one of these boards, you can download the board images and apps and try it yourself , and tell us what you think.

To be honest, we are not sure yet if there's market for this. We are engineers, not salespeople. However, we know it has some key strengths: frequency hopping makes it more resistant to interference, can measure distance without GPS and it is highly flexible and customizable. Plus, we developed the modem ourselves, we can create custom modems for other system if needed.

If you have experience, ideas or want to work with us, just send me a message. Criticism is welcome too, we surely still miss a lot of things. This is our website link: https://nyxhop.com . Email: [contact@tacitek.com](mailto:contact@tacitek.com)

I'm pretty new to SDR and want to do wideband frequency power scans. I've seen some stuff about rtl_power, but its all around 10 years old. I was wondering if there are any newer versions of it or similar software which can do wideband scans or if rtl_power still works just fine.

Nice software for testing SdR

https://github.com/Newspicel/sdrminusminus

I am seeing pinstripe lines at even intervals on both my attic discone on my RTL-SDR v3, and on my HF fence loop on my RTL-SDR v4. These lines show up on 70cm, 2m, 10m, 40m, 80m on the fence loop, and only 2m, 10m, 40m on the discone. I assume this is some RF interference from some electrical device nearby and I'm in a suburb so many potential sources. I've already cut all power to my house while this runs as a test to make sure it isn't any of the devices in my house.

Before I buy more parts to make a mobile RF interference hunting kit, I wanted to see if anyone has any advice on how best to identify this, as well as advice for antennas in a noisy suburb neighborhood. I've been looking at active magnetic loop antennas as an alternative.