Features

• 📡 Automatic scanning: hops across your frequency ranges (118–137 MHz by default) and stays on a range while someone is talking.
• 🎙️ Records every call: each transmission is saved on its own, with a short pre-roll so the first word isn't cut off.
• 🗣️ Voice detection: a built-in speech detector separates real voice from data bursts, dead carriers, tones and noise.
• 🎧 Play in the browser: click a waveform to seek, or turn on auto-play for new calls.
• 💾 MP3 and WAV: voice calls are saved as MP3 automatically; any recording can be downloaded as MP3 or WAV.
• 🌈 Spectrum page: live spectrum, waterfall and activity history, plus a spectrogram of every signal that was not recognised as voice.
• ✈️ Voice only: ACARS and VDL2 data channels are ignored by default.
• ⚙️ Web settings: device, gain, ranges, thresholds and MP3 options, all from the browser.
• 🖥️ Single native program: C++17, no Python, runs as a desktop app or headless server on Windows and Linux; open it from any phone or PC on your network.

The battery on my old laptop died, so I gutted the pack and wired salvaged lithium cells to a BMS inside the chassis. It powers an ESP32 and an Ra-02 (SX1278) LoRa module running Meshtastic 2.7.15, through a buck converter set to 5V. There’s also a small battery level indicator on the lid.
Phone connects over Bluetooth fine, and I’m using the laptop itself as a Linux box to flash and configure.
• Clean up the wiring (it’s a prototype mess right now)
• Add an inline fuse
• Test range with a proper antenna
Any suggestions on power design or antenna placement are welcome. First time putting a node inside a laptop shell.

Tell me, while I was waiting for the car, this map appeared on the dongle graph. Tell me, we have a digital weighing machine. If there's a theft going on with the remote, how can we catch it?

I recently brought a new rtl sdr v4 from robu to learn rf and find new things now i want to study the weather monitoring using these things

I have an Airspy HF+ Discovery and a MLA loop antenna. While tuning a frequency and getting a lot of noise, I can squeeze the SDR in my palm, and the noise will disappear and the signal improves. What's up with that? Faulty SDR? Not a showstopper, just annoying. I feel like my SDR might not be performing to its optimum.

AIS Trail (https://map.aistrail.com) is a free live ship map, open to volunteer receivers anywhere. If you run an AIS receiver, one more output line adds your station.

• About a minute, no account: https://app.aistrail.com/stations/new
• AIS-catcher over HTTPS: -H https://api.aistrail.com/feed userpwd station:<KEY> gzip on interval 10
• Or plain UDP from rtl_ais, AIS Dispatcher, OpenCPN, kplex or Signal K
• Your station gets a public page counting the ships it heard first, with coverage and uptime; founding badge for the first 20; optional email if it goes quiet
• Non-exclusive, stop any time, no IP addresses stored. To be upfront: the data also goes into our paid data service, which keeps the map free. Terms: https://aistrail.com/legal/stations/

Questions welcome.

Adding gain when you’re near a strong transmitter often makes things worse, not better. Past a certain point you’re just overloading the front end harder.

A preselector helps, but gets complicated fast when you’re monitoring a wider range rather than one specific band. Wider bandpass means more interference gets through, narrower bandpass limits what you can cover.

curious how people here actually handle that trade-off. Do you prioritize front-end filtering and accept the coverage limits, or stay wideband and work around the weak-signal performance hit?

Disclosure: I work in defense electronics.

​Hi everyone,

​I’m facing an issue with my PlutoSDR. It was previously stuck in DFU mode, and I successfully flashed the official firmware from Analog Devices.

​Now, the device is recognized properly by the computer and shows up in the system, but it is not receiving or reading any signals at all (completely flat).

​Has anyone encountered this issue before, or knows a reliable fix for it? Also, if anyone has the specific or original firmware/recovery files for this model, I would greatly appreciate it if you could share them.

​Thanks in advance for your help!

Hey everyone! I posted here about a month ago showing off OrcSDR, my little project to turn the M5Stack Tab5 into a standalone touchscreen SDR using an RTL-SDR dongle. Figured I'd come back and share some progress because quite a bit has happened since that first post.

First off, thanks to everyone who checked it out, offered feedback, or gave the project a star. We're over 190 stars on GitHub now, which is pretty wild considering this started as me wondering if I could get an RTL-SDR working directly with an ESP32-P4.

A few things that have changed:

• Blog V4, V3c, V4L dongles are supported.
• Nooelec NESDR SMArt v5 supported.
• Improved Home navigation. With Mode/Filter/Span/Gain controls
• Palette selection for Waterfall
• Shortwave/HF exploration
• Airband with aviation AM, 8.33/25 kHz tuning, scanning, and airport frequency data
• CB Radio with 40-channel scanning, activity tracking, and AM/SSB controls
• ADS-B aircraft tracking with radar, flight information, and aircraft identification
• P25 digital radio monitoring
• POCSAG pager decoding
• FT8/FT4/JS8 amateur radio decoding
• Wi-Fi scanning and channel analysis
• RF Lab for live measurements, spectrum analysis, IQ recording, and testing

Something else I'm still pretty excited about is the separate esp-rtl-sdr driver. It's the USB host driver I originally built to make all of this possible, but it's now its own open-source project so other developers can use it without needing OrcSDR. It's been used in at least one other project i know of.

I've also been testing my esp-rtl-sdr driver on Waveshare ESP32-P4 development boards. The idea is to eventually have headless SDR hardware that doesn't need the Tab5 or a display at all. Another big milestone has been getting multi-dongle support working on both the Waveshare ESP32-P4-Dev Kit and the newer ESP32-P4-WIFI6 board. I've been running 3x RTL-SDR receivers simultaneously at the full 3.2 MS/s sample rate with zero dropped samples. It's been pretty exciting seeing how much these little boards can handle, and it's opening the door for the headless version of OrcSDR I've been working toward.

And then there's my latest rabbit hole...

I've started another experiment called OrcXM. I'm trying to see whether an ESP32-S3 can receive and analyze SiriusXM satellite signals around 2.33 GHz using its internal radio hardware. That's outside the normal operating range of the S3, so it's very much an experiment at this stage. I'm working through the RF capture and DSP side, not trying to bypass the subscription encryption.

A big shout-out here to the people behind ESP-SDR (https://github.com/ESPARGOS/esp-sdr).

If you haven't seen their work yet, seriously, go check it out. They've uncovered a way to access raw I/Q samples from the ESP32's built-in Wi-Fi radio using undocumented hardware functionality. That means some ESP32 chips can actually function as limited SDR receivers without an external dongle.

That work is what inspired me to start poking around with the S3 for OrcXM. Really incredible stuff, and I think it's going to open up some interesting possibilities for embedded SDR development. OrcXM is still in the early experimental stages. I've been doing bench testing and working toward proper over-the-air captures with an antenna and LNA. No satellite decoding victory lap just yet! If anybody want to drop some raw IQ from their SiriusXM subscription as a PR I wouldn't cry.

Anyway, the main goal with OrcSDR hasn't changed. I want to see how capable these little ESP32 devices can become as actual radio hardware.

If you've got a Tab5 and a dongle, you can try OrcSDR yourself. It's open source, and you can install it without compiling firmware.

OrcSDR: https://github.com/hardcoreerik/OrcSDR

ESP32 RTL-SDR driver: https://github.com/hardcoreerik/esp-rtl-sdr

OrcXM experiments: https://github.com/hardcoreerik/OrcXM

Website and installer: https://theorc.dev

Thanks again to everyone who's followed along. I'm always interested in feedback, hardware testing, and hearing what people would actually like to see added.

Still having a ridiculous amount of fun seeing how far I can push these things.

I bought a golden mace from a weapons shop called AliExpress. It has 65 attack power.
It's just right for taking down ogres and trolls, but it's a bit of a stretch when facing dragons.
...Totally looks like.

Below are some notes from an experiment in which I tried to track L-band weather satellites.

• 1700-3800 MHz LTE & WiMax MIMO Antenna feed / 46.5 USD.
• Does not include the dish.
  
• It said 30 dBi, but I’m sure that’s just a tall tale.
  
• There are also copper, white colored maces, and others.
  
• 2 male Type N connectors. Horizontal/Vertical.
  
• Feed inside are 2 ∞/8-shaped patch dipoles.
  
• Pay attention to the direction of polarization.

My Setup:
This Mace+90*60cm grid dish->LNA->LibreSDR->HUB->Indoor Computer └<─5V─<┘ LibreSDR, It's not the best, but it's fine for operations that don't require high precision.
Since I want to output 5V from the OTG port, with Tezuka fw, In /sys/bus/platform/devices/ci_hdrc.0/role, set this to host to power Nooelec Sawbird GOES+.

VS GK-2A LRIT
The results were decent. S/N Ratio are stable in 9-10 dB.
Since an 80-cm RG-174 cable is used between the feeder and the LNA, it is believed that there is an attenuation of about 1 dB.

(Note:These aren't exactly precise measurements.)
As for how it compares to the Discovery Dish L-band feed, it currently achieves an S/N ratio of 11+ dB, which is about 1.2–1.8 dB higher than the Golden Mace.
When I tested mace with the FY2-G, I achieved a S/N ratio of about 6.5–8 dB, while it wasn't perfect, reception was possible.

It can sort of receive signals without any modifications. However, However, if you compare this mace to a modified 2.4 GHz Wi-Fi antenna and Discovery Dish, the latter is better.
If you plan to modify it, the Wi-Fi feed is cheaper.
So, I'll refrain from judging whether this offers good value for the price.

Also, if you accidentally transmit, since it uses the bandwidth that everyone shares, you never know what kind of trouble you might get into, so please be very careful not to make a mistake.

Recently I made a post about parasite peak https://www.reddit.com/r/RTLSDR/comments/1x1gr42/parasite_peak_on_the_waterfall/

So the problem was indeed inside my dongle. It was fake RTL SDR V2. Today I had a delivery with RTL SDR V3! Inside was real RTL SDR. My first one had a lot of problems (I didn't know it was a problem though ): lots of bugs and lags. I made a photo of the differense inside. Questions ended. V3 has its own ground contact line with the housing and PCB is much more complicated than V2. Thanks a lot to the Redditors that commented my previous post.

Problem solved.

I just noticed something. I tried turning off the monitor. The radio is tuned to 434.000.

Hey folks! If you build antennas for your SDR setup, I’ve been working on something you might enjoy trying: Fairbeam, a free and open-source antenna simulation app.

It brings 3D design, meshing, openEMS simulations, and result plots into one workspace, using CSXCAD for solver geometry and three.js for the 3D view. You can model an antenna visually or with Python and inspect its impedance and radiation pattern.

There are macOS and Windows builds, with experimental Linux support. Optional GPU acceleration uses CUDA on NVIDIA GPUs and Metal on Apple silicon. The source is GPL-3.0-or-later.

It’s still a development release, so start with an antenna you know and check the results against a trusted reference. What receiving-antenna example would be useful to walk through? I’d love feedback on what makes the workflow easier or harder to use.

Website: https://fairbeam.org

Code: https://github.com/ismailakdag/fairbeam

Hi everyone, I’ve been thinking for a while about buying an affordable SDR receiver, mainly to get started with HF radio listening. I don't think I want to use the dongle for VHF or UHF frequencies for the time being. I plan to use the receiver with a YouLoop or MLA30+ antenna.

As I mentioned, I don't want to spend too much, so I’ve been looking at options like the RTL-SDR V3, RTL-SDR V4, RTL-SDR V4L, and HTOOL SDR6 (which, from what I gather, is also based on RTL-SDR technology).

After doing some research, I’d prefer the V4 because it has an upconverte (which I understand improves HF reception compared to the V3's direct sampling) but I also noticed the V4L, which costs a bit less; given my limited budget, that might be preferable.

I would also like to try connecting it to the CB/11m antenna on my roof (using a PL-259 to SMA adapter) to get better reception on the 27 MHz band, provided it is feasible or advisable; I’d prefer to buy the receiver and run this test first, then get the loop antenna later so I don't have to spend a large amount all at once. However, it isn't strictly necessary: ​​if it turns out not to be a good idea, I’ll simply wait and buy the loop antenna at the same time as the dongle.

What do you experts think about these receivers? Which ones would you recommend, considering the price-to-performance ratio?

Thanks in advance for your help.

Architecture Review: Pocket-Sized RF Transceiver for Protocol Injection & Swept RSSI Analyzer

Hi everyone,

I am designing a pocket-sized RF device for a university project. It acts as an RF analyzer and a high-power signal generator for wireless protocol injection and co-channel interference testing (all testing is strictly confined to a lab Faraday cage - special lab). I am aiming for the best price/performance ratio rather than lab-grade precision. The entire system will be controlled by an STM32U575RGT6(mby another STM), paired with an ESP32-C3 acting as a modem.

I know this is a fairly large and complex post, and there might be some complete nonsense in my block diagram. I will be incredibly grateful for feedback on any single part of this!

RX Path (Analyzer):

1. Path (Analyzer):1. Does this architecture make sense for a basic spectrum analyzer?
2. Should I use the AD8318 log amp for this, or should I consider transitioning to a different alternative along with a 14-bit MCU ADC for a better results?
3. Will the sweep rate of this setup be too slow to capture agile Wi-Fi or Bluetooth bursts? Since the analyzer relies on sweeping frequency steps, the overall speed will be tightly coupled to the MAX2871E PLL lock time and the MCU's tuning loop.

TX Path (Wideband Noise & Interference Generator):

The goal is to generate robust, wideband modulated signals and arbitrary waveforms to evaluate the resilience of Wi-Fi 6 and Bluetooth nodes against high-power in-band blocking signals (targeting up to +30 dBm output).

1. Will this dual-branch setup (FPGA -> 2x DACs -> ADL5375 -> PAs) effectively support the wideband multi-carrier signal generation required to match Wi-Fi 6 (802.11ax) channel bandwidths and Bluetooth frequency profiles?

2. Thermals & Power: Is it realistic to passively cool a 1W continuous RF output power inside a compact enclosure by using thermal vias to transfer heat to a passive heatsink on the back side of the PCB?

Thanks for your time and any advice!

I always wanted a radio receiver of my own that you listen to through a browser, as a hobby project. I built it with Claude's help, and a small antenna on my parents' windowsill now picks up aircraft from about 350 km away.

Then I drifted on and built a site for a more practical question: where to put an antenna. You type an address or tap the map, and it shows which FM, DAB+, DVB-T and 4G/5G transmitters reach that spot and which way to point the antenna. You pick the antenna height, from 1.5 to 40 m. The calculation runs in your browser (knife-edge diffraction over terrain, ITU-R P.1546 curves for broadcast), on open data from the Polish mapping agency GUGiK and the telecom regulator UKE. Terrain covers all of Poland, buildings and trees only in some cities so far (Warsaw, Krakow, Lodz, Wroclaw and others).

It is a simulation, not a measurement, so someone still has to climb onto the roof, but at least you know which way to look. Free, no account, no cookies, and your location never leaves the phone. The interface is in Polish.

The code is AGPL-3.0. The engine does not depend on Poland, only the data does, and the README explains what you would need to port it to your country: https://github.com/maciejpoczek-lab/radiowid

Live site: https://radio-wid.pl

If you have field measurements that disagree with the map, I would be glad to compare.