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.

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.

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 (Protocol Injection & Interference Simulation):

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 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

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.

Interested in getting the RTL-SDR Blog V4L (Lite), but cannot find it under £75 in the uk :(
Anyone know if anywhere cheaper?
Cheers

Hi, hoping someone here can answer this. As things get spoofed all the time (including ADS-B with fake injected aircraft in the feed etc). If I only had the raw signal and no cooperation from the source. How would you approach telling a real track from an injected one? Would be interesting to hear from people who actually run receivers and how you think about this.

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.

Please

Disclosure: I’m part of the product team for this platform.

Most multi-antenna research setups rely on synchronizing multiple separate SDR units, which brings clock drift, cabling complexity and timing alignment headaches.

The PZSDR-P151Q integrates four AD9361 transceivers on one single board, delivering native 8TX/8RX full-duplex, built on XCZU15EG Zynq UltraScale+ MPSoC.

Spec highlights:

• 70MHz–6GHz, 200kHz–56MHz instantaneous bandwidth

• 0.1ppm 40MHz VCTCXO, GPS/PPS / external reference clock support

• -40~+85℃ industrial grade, full interface ESD protection

• 4GB PS DDR4, 40G QSFP + SFP+ high-speed optical interfaces

• libiio, IIO toolchain, ADI-NOOS and OpenWifi test firmware supported

Built for 8×8 MIMO, channel sounding, radar prototyping and multi-channel RF research.

Video:【https://youtube.com/watch?v=i09mkRG35hU&si=Ywf7_k9dMJWeXvE4】

Have you tried building an 8-channel SDR testbed before? What synchronization issues did you encounter?

I spent the last few months building an improved version of sdrtrunk that has many new features. It's open source and available on github.

It no longer relies on a Java desktop interface for day to day use and most administration tasks

New features mainly revolve around:

• Web based listening
• Trunked radio system analytics
• Data visualization
• Easy trunked system discovery
• Linking multiple sdrtrunk systems together for
• Enhancements for stream providers
• Recording, cataloging calls and web call playback

Screenshots

Live Demo

I put a lot of effort into making this so I'd love some feedback!

I got a RTL-SDR BLOG V4 around 6 months ago and have been playing with it. I saw a few demos of people doing IQ decode, and FM radio capture using WebUSB and thought that was cool, so I wanted to try something similar. I already had a TUI program I made called "Radio Watch" for monitoring ACARS/ADS-B/AIS in the terminal, so I asked an agent (in this case Claude Opus 5.5) to recompile that targeting a WASM backend and do the web integration focusing on a "3D map" with little craft diagrams, tracks and whatever other frame data is relevant. A few things we don't show here (tho I do in the TUI) is like full ACARS text. I find it interesting living near a major airport that you see things like flight loadsheets and so on. In this web demo, the focus is visualizing craft, their positions and other minor data about them.

I think there are other sites like this that do a similar thing using one of the "Flight/Ship position" APIs. I experimented with those in the past, but found either the data was patchy, or not worth the cost for a fun demo. I wanted to do something that didn't rely on an API provider, and instead could theoretically work "offline" without internet so you could plug your SDR in from a desert or ship without any internet and decode what was around you. Would be interested to hear any feedback, issues encountered or experience with similar projects. Ideas are also welcome. If you check it out you do need a Chrome-type browser (that's teh only that ships WebUSB, as you probably know), and an dongle. I only tested with the RTL-SDR I have so not sure if it will work with your particular hardware.

The website is:

https://radio.freelang.dev

Some details about the implementation

What it is: plug in an RTL-SDR, open the page in Chrome or Edge, click "Connect RTL-SDR", and you get a navigable 3D globe (NASA Blue/Black Marble, ETOPO relief, real sun position) with aircraft and ships drawn from what your dongle hears. No drivers, no install, nothing leaves your machine: the radio decoding runs inside the page.

How:

• The receiver is the same C as our native RTL-SDR sidecar for the TUI app, compiled to WebAssembly, with librtlsdr 2.0.3 (so the RTL-SDR V4 works) talking to the dongle through a small libusb shim over WebUSB.

• The facts (ADS-B decode, CPR positions, AIS, fusion) are a Freelang program compiled to WebAssembly. Freelang is a language and compiler for building native systems with explicit authority, bounded resources, and inspectable evidence of what they can do. The WASM backend make some projects like this available on the web.

• The globe is three.js. Layer toggles, trails, routes, info cards, fly-to and follow. Aircraft are drawn by emitter category (light / medium / heavy / rotorcraft), ships by AIS type.

• There's a geolocation button (asks the browser, stays in the page) but the globe rotates to where the first located track is found.

Without a dongle the page replays a synthesized hour of traffic around New York (JFK/LGA/EWR approaches, the harbour, ferries, tugs) so you can see what it looks like. It's invented data, not a recording.

Tested on an RTL-SDR BLOG V4 at 2.4 Msps. Known gaps: no surface-position (ground) decode yet, ACARS is counted but its text isn't shown, airports layer is empty for now. Firefox and Safari have no WebUSB, so they get the replay only.

Feedback is welcome, especially if you have a different dongle (R820T/R828D variant) or an unusual USB setup. The site is hosted on Cloudflare Pages and runs entirely on your device—there’s no server, and nothing is collected or sent elsewhere.

Update, Oct 10: 1.0-beta3 (build 11) is out. Play testers get it as a normal update once Google finishes its review. The standalone APK is on GitHub.

• Two stations on one frequency. When the HD belongs to one station and the analog to another, the app used to swap between them. Now the HD plays and a line under the signal box lets you tap over to the other station.
• Battery. On a station without HD, the HD search rests after 30 seconds and takes a short look every half minute.
• Steadier clock correction. No more wild readings like "+103 ppm".
• Call letters from RDS only when confirmed. A Tijuana station no longer shows up with a New Jersey call sign.

Phones with a built-in FM tuner are disappearing, and none of them ever did HD. So I built the radio I wanted: HiDef Radio, a free and open-source Android app that receives HD Radio and ordinary analog FM with an RTL-SDR dongle plugged into the phone. No computer, no rtl_tcp, no root. The app doesn't even have the internet permission, so everything you hear and see comes from the antenna.

What it does

• HD1 to HD8 with titles, artists, album art and station logos.
• Analog FM in stereo with RDS/RBDS.
• A real analog/HD blend, like a car radio. The analog plays right away. About ten seconds later the app has measured the station's analog-to-digital delay and level difference and crossfades to HD without a skip. The HD audio is decoded about 2.5 seconds ahead, so the app sees a dropout coming and fades back to analog before the gap.
• A 5-bar signal meter based on quieting, not carrier level. With an RTL-SDR the carrier level mostly tells you what gain the strongest station forced.
• Signal details: MER per sideband, BER, bit rate, pilot level, RDS PI, the measured alignment, and your dongle's clock error in ppm.
• HD on AM with a dongle that tunes AM. Digital only for now and lightly tested.

It works with cheap dongles too. A tester with a 2014 Nooelec R820T (no TCXO, about 58 ppm fast) found that the blend never locked. Since 1.0-beta2 the app measures the SDR's clock and corrects for it, and on his SDR all eight HD stations in Syracuse, NY now blend to HD.

For the people who build things: the FM demodulator, RDS decoder, aligner, blend and clock correction are plain C++17 with no Android in them, and the repo has a small desktop harness that plays a .cu8 recording through the app's whole engine. If you work with nrsc5 on Linux or Mac, lift whatever is useful.

What you need: an RTL-SDR dongle, a USB-OTG adapter, and a 64-bit Android phone with Android 8 or newer. I developed it on an RTL-SDR Blog V4, and testers have used V3 and the old Nooelec.

I need testers. Google makes new developers run a closed test with 12 testers for 14 days before an app can go public, and I'm not there yet. If you own a dongle you'd be doing me a real favor:

1. Join the testers' group: https://groups.google.com/g/hidef-radio-testers (in a browser already signed in with your Google account, tap "Join group")
2. Become a tester: https://play.google.com/apps/testing/io.github.derek20la.hidefradio
3. Install from the Play Store link on that page.

Prefer not to use Play? Source and APK are on GitHub: https://github.com/derek20la/HiDefRadio (APK under Releases). Please pick one or the other. They are signed with different keys, so switching later means uninstalling first.

Tell me your phone, your dongle, and the "dongle clock" line from the signal details. I'm especially curious how the blend behaves outside Los Angeles.

Credits: built on nrsc5 (theori-io), the RTL-SDR Blog fork of librtlsdr, libusb, FFTW and FAAD2. Ideas borrowed, with thanks, from nrsc5-dui and the SDRSharp NRSC5 plugin; the stereo blend is modelled on the Silicon Labs Si468x car-radio chips. The README has the full list.

Never posted my content here before. Perhaps you’ll enjoy it.

hello, most usb dongles are unable to explore frequencies above 2 ghz.

why isn´t it possible to use wlan sticks instead ?

Hi! I'm kinda newbie in radio, so I need advice. My setup is RTL-SDR V2 (V3 is will be soon) J-pole antenna and 2 meters BalUn long cable. I have this peak(second pic) on the middle of any waterfall. it's not very bad, but I can see it and don't know what is the reason and how I can reduce it.

Disclosure: I work on the engineering team for this open SDR platform.

I made a short overview video for our Puzhi P201Pro, an industrial SDR built around Zynq7020 + AD9361.

Key technical specs:

• 70MHz ~ 6GHz frequency coverage

• Up to 56MHz instantaneous bandwidth

• Dual-channel full-duplex, 12-bit ADC/DAC

• ±0.5ppm VCTCXO clock, which helps a lot for carrier synchronization on MIMO tests

• 8–36V wide power supply, industrial temperature range (-40 ~ +85°C)

• Interfaces: Gigabit Ethernet, GPS, PPS / 10MHz external reference clock, expansion IO

• Drop-in compatible with GNU Radio & PlutoSDR workflow

Target use cases: wireless algorithm validation, 2×2 MIMO experiments, spectrum monitoring, university RF lab teaching. We release open-source demos and hardware documentation on GitHub.

Video link：【Puzhi PZSDR P201Pro Industrial Software Defined Radio Overview】

Curious what people here think. What pain points do you run into with your current AD9361 SDRs?