r/sdr

We are beginners exploring satellite communications. Failed many times so Need help to make an RTL-SDR setup to collect images from geostationary satellites
Any satellite preferably FengYun-2H
Where can i buy the antenna and its component online.

Hey everyone,

I’ve designed a reconfigurable uniform polyphase channelizer optimized for FPGAs, targeting two major pain points in conventional implementations: limited configurability and excessive hardware resource overhead.

Compared with classic polyphase channelizer architectures, this design supports one-time hardware instantiation with runtime reconfiguration, fully pipelined dataflow, and single-cycle throughput.

Here are the core technical capabilities:

1. The hardware is sized for a maximum channel count C and subfilter tap length K. After deployment, it can dynamically work with any channel count c that is a power-of-two divisor of C.
2. Under any selected channel count c, the design supports arbitrary decimation factors ranging from 1 up to c.
3. It accepts arbitrary filter coefficient sets with total tap lengths less than \(c \times K\).

In terms of FPGA resource consumption, the overhead is nearly identical to a standalone decimation filter of length K paired with a serial C-point IFFT block.

I’ve conducted a thorough literature and patent search, and I cannot find any existing published work or granted patents that deliver this full set of flexible reconfiguration capabilities.

State-of-the-art polyphase channelizer implementations only optimize resource usage or throughput for fixed, narrow application scenarios. Most existing designs are constrained by serpentine shift registers and circular output shifting logic, which rules out flexible runtime reconfiguration.

Many fixed-function channelizers achieve higher raw throughput, but that performance comes at the cost of rigid hardware partitioning and locked parameter modes. I believe further speed optimizations are still possible within my flexible architecture without sacrificing its reconfigurability.

I’m reaching out to ask for industry/research perspective: does this reconfigurable polyphase channelizer hardware architecture carry meaningful commercial or IP licensing value?

Thanks a lot for any insights!

Anybody seen this new law  https://www.legis.ga.gov/legislation/72945

The definition of device is very broad and covers many radios used in ham and other rf hobbies. I mean technically a Router running DD-Wrt would fit the definition as it could be used to deauth devices. It doesn't just say using the device while jamming, but merely possessing a device capable of doing so.

'Signal jammer' means any device, instrument, or apparatus which through emitting  

a signal is capable of preventing, disrupting, delaying, degrading, or otherwise interfering with the transmission of a communication signal over:  

(A) Any wireless communications system, cellular communications system, radar  

system, or global positioning system; or  

(B) Any radio, telephone, or cable line, station, or system.  

(9) 'Vital public services includes water, sewerage, drainage, energy, electric, gas, natural  

gas, telecommunications, internet, cable, navigation, collision avoidance, public  

transportation systems, railroads, and other services the loss of which would have a  

debilitating impact on the health, safety, or financial security of the public.

Hi everyone,

I'm currently working on my high school graduation project (Maturaarbeit in Switzerland) and I'm stuck on a frustrating DSP/SDR issue. I'm hoping some of the experts here might be able to point me in the right direction.

The Project: I am building a custom, license-free wireless protocol to bridge the gap between Wi-Fi (high bandwidth) and LoRa (high range). It operates in the 2.4 GHz ISM band using a 10 MHz bandwidth and a low Spreading Factor of 5 (SF5). To increase the data rate beyond standard LoRa, I expanded the modulation:

• CSS (Chirp Spread Spectrum) as the base.
• Slope-Shift Keying (SSK): Using both up- and down-chirps (+1 bit/symbol).
• QPSK: Embedding phase offsets into each chirp (+2 bits/symbol).
• LDPC: Forward error correction (IEEE 802.11n based).

The Setup & Code:

• Hardware: 2x ADALM-Pluto (modded to AD9361 for 56MHz BW), TCXO 0.5 ppm.
• Software: Built entirely from scratch in Python (NumPy, libiio). I purposely didn't use GNU Radio because I wanted to code the math and DSP pipelines myself to understand them fully.
• GitHub Repository: You can find the complete source code and simulations here:https://github.com/Valix-s/CSS_Hybrid_Modulation/tree/main

The Problem: My baseband simulation (including an AWGN channel and the full LDPC pipeline) works flawlessly, even at negative SNRs. However, when transmitting over the air, the packet synchronization fails completely. The receiver is unable to reliably detect the preamble (packet start). If the start index is off by just a few samples, the symbol boundaries shift, and the dechirped payload turns into garbage.

What I've tried so far:

1. Time-Domain Cross-Correlation (scipy.signal.correlate): Failed completely over the air. The slight Carrier Frequency Offset (CFO) caused phase rotation, leading to destructive interference when correlating over the 16-symbol preamble. Wi-Fi bursts in the 2.4 GHz band also caused massive false positives.
2. Frequency-Domain Sync (Dechirp + FFT): I switched to a sliding window approach using pure NumPy. I multiply the incoming signal with a local down-chirp and run an np.abs(np.fft.fft()) to find the peak, avoiding phase rotation issues. It works perfectly in simulation, but still fails on the actual hardware.

My Suspicions:

• Python Processing Latency: My pure Python DSP loop might be too slow. While processing a chunk, the PlutoSDR hardware buffer might overflow/overwrite, effectively "cutting" the preamble in half.
• OS Timing Jitter: I tried implementing a rudimentary TDMA slot system to separate TX and RX windows and give Python time to compute, but Windows OS timing jitter makes my slots highly inaccurate.
• 2.4 GHz Interference: The AGC might be getting crushed by high-energy Wi-Fi bursts, suppressing my preamble peaks.

Next Steps: I ordered u-blox NEO-6M GPS modules to extract the hardware PPS (Pulse Per Second) signal via an ESP32 to enforce strict, hardware-level TDMA slots and eliminate the Python/OS timing jitter.

My Questions for the Community:

1. Has anyone implemented a custom CSS/LoRa sync algorithm in pure Python? How did you handle continuous buffer reading vs. heavy processing time?
2. Are there any known tricks for robust preamble detection in heavy ISM-band noise environments using PlutoSDRs?
3. Am I overlooking a fundamental hardware limitation when doing 10 MHz wide CSS via libiio in Python?

Alot of you tinker with these on here. What's some of your takes on it?? I've started out with SDRPLAY rsp1B and I'd like to broaden my horizons with the Airspy! Tell me! Blow me up!

​

Hi, I'm in a real hurry to find a fixed salary or commission-based income, so I've been researching this topic. I learned the basics at HubStop through their free training, but it's very introductory, although I liked the format. I have a general understanding of using CRMs, but I don't know how to move forward. What should I do now?

I am a Spanish speaker and I have a B2 level of English fluency. If you help me, I would really appreciate it 🙏

Hey r/RTLSDR & r/SDR! 👋 I’m xyz‑rainbow, and I’ve been building xyz‑sdr, a Python TUI SDR controller that works with any SoapySDR device (RTL‑SDR, HackRF, Airspy, SDRplay, etc.).

Here’s what it looks like (FFT + Waterfall + Timeline fully synchronized): [Demo xyz-sdr] - https://github.com/user-attachments/assets/6bf02f3e-dbbf-41fc-9be9-94ce2defc04c

What main features xyz‑sdr does today

• Loadable band profiles (FM, Airband, PMR446, HF‑LSB, etc.)
• Bookmark system for save frequencies
• Demod modes: WBFM, NBFM, AM, USB, LSB, CW, DSB, RAW, "auto"
• Band scanner while RX is active
• IQ bandwidth presets 250 kHz → 8 MHz
• DROP‑rate indicator + debug mode Simulation mode (run the full TUI with no hardware): run.ps1 --sim

Im using this stack; python 3.9–3.12 · SoapySDR · pytest/pytest-cov · TOML config primary: Windows 10/11 (with DX packaging + installer scripts) Linux/macOS: scripts/run.sh (works, less polished — help welcome!)

I'm looking for collaborators and Hardware testers,

Especially: HackRF, SDRplay, Airspy
(But anydevice helps) Even without hardware, -Sim mode lets you run the TUI without any hardware and see the app working with simulation audio. Linux/macOS testers — the shell launcher works but I haven't tested nothing on those OS :( DSP contributors — demod pipeline is functional but minimal; FM stereo, NFM, AM demod improvements are needed asap TUI contributors: If you know Python, curses, urwid, textual, or just enjoy terminal UI work you’re welcome. Any feedback — bugs, missing features… UX, missing band profiles etc.. it needs much works, its the first version

Repo: github.com/xyz-rainbow/xyz-sdr
Roadmap: roadmap.md

Thanks!

Usefull commands: (windows only for now)

.\setup\install_drivers.ps1 .\scripts\run.ps1 .\scripts\run.ps1 -Driver sdrplay .\scripts\run.ps1 -Check

Hello everyone! I am new to the hobby and got a rtl sdr v3. It came with the sdr and an antenna package, i am trying to listen to my local dispatch using a trunked software but i cannot seem to find any signals.

I dont know enough about this so i did a little research with ai and it said it was likely due to the antenna, ive tried using the smaller antennas and put them to 3.7 inches and mount them where one was facing the ceiling and another the floor. This helped but it was still a very weak signal and nothing would come through the software. It still said idle even when i could see stuff being transmitted via openMHZ.

I am about 30 ish miles from the main dispatch tower. Is it possible to receive this with this antenna or any antenna?

Thank you for your help!

https://preview.redd.it/mavxfhgmy49h1.png?width=500&format=png&auto=webp&s=d0e028e17922e03d49dbf78f4f0548d3fce567ac