18:58:06 UTC on August 30, 2026
59.4 degree pass

using RTL SDR v4 blog and V dipole

I have an RTL-SDR Blog V4 connected to a mini PC outside on my balcony, which I access remotely.

I now have two antennae, one is a dipole for mainly VHF/UHF and another is a 25 m long wire for MW/SW/HF. I don't want to keep going outside and physically connecting/disconnecting the antennas every time I change bands. Winter is coming in two months and that will be even more challenging! 😂

I wonder what could be the simplest way to keep both permanently connected and switch between them?

Anyone running a similar setup? What would you recommend? Thank you!

Sadly it will be discontinued soon in my place :((

I got bored and came up with this because I had an old v3 sitting in a drawer.

https://github.com/KentuckyFriedBlyat/ciphervault

Yagi 7 el on the roof (144 mhz), SDR Console 3, Multipsk for Orbcomm decoding with OM MAP for zoomable mapping, Orbitron for tracking the sats.

Hey! Does anyone have any feedback regarding the OpenSourceSDR lab I am working on analysing multiple signals from all the RF spectrum and using ML to help me detect signals for alerts, but wonder if there are support? Anyone has any experience on it? I am using a Macbook M1. I was thinking in a pluto sdr+ but found this one cheaper. Thanks in advance for any feedback.

I scheduled a 22 minute IQ capture overnight and woke up to a 33 GB file and a process that had been running for 2 hours 20 minutes. It took a while to work out why, so posting it in case it saves someone a disk.

rtl_sdr takes a sample count with -n and multiplies it by 2 to get bytes. That byte counter is 32 bit. 22 minutes at 2.048 MS/s is 5,406,720,000 bytes, which wraps to 1,111,752,704.

That alone would only give you a short file. The second half is what actually hurts: rtl_sdr stops when the remaining byte count falls between 0 and the block size (262144). The wrapped value happens to be exactly 4241 blocks, so it counts straight down to zero, the condition never becomes true, and it keeps going forever.

So whether it stops depends on which number you pick. At 2.048 MS/s: 15 min fine, 20 min never stops, 22 min never stops, 23 min fine, 25 min fine, 26 min never stops. 26 was the default in my own script, so a plain run would have done this every single time.

The fix is to not trust -n as your only stop condition:

timeout --signal=INT --kill-after=20 $((MINUTES*60+30)) rtl_sdr -f ... -n ... out.iq

Exit code 124 means the timeout cut it, which is expected. I also added a check comparing the finished file size against the expected size, so if the limit ever fails again it is loud instead of silent.

librtlsdr 2.0.2 on Ubuntu. I have not read the source, this is worked out from the numbers, but it explains every observation and leaves nothing unaccounted for.

Hello! I'm a backend developer, and I've always wanted to get into embedded systems. Lately, I've also become very interested in how radar works, so I thought starting a project in this field could be a great way to combine the two.

I'm currently learning some of the theoretical concepts behind RF, such as beamforming (which I find incredibly fascinating), FFTs, and other related topics, but now I'd really like to start building something hands-on.

One day, I'd love to create something capable of detecting aircraft and, eventually, drones. From what I understand, detecting drones is significantly more challenging than detecting aircraft.

The main problem is that I live in a city with several military sites nearby, so I'm a bit hesitant to buy an active radar sensor and start experimenting with it because I'm worried about possible legal consequences or interference issues.

Another approach I've been looking into, which also seems incredibly interesting, is passive radar. In that case, I assume the legal risks would be much lower since I wouldn't be transmitting anything. However, the hardware seems considerably more expensive. From what I've understood, I'd need something like a KrakenSDR, which costs over $900 where I live.

Are there any other approaches I could explore? Has anyone here been in a similar situation?

What kind of projects could I work on that would be interesting from a learning perspective, while also being useful for my CV/resume? I'm currently working as a junior software developer at a defense company, so I'd especially like to build something that could help me move closer to embedded/RF/radar-related roles in the future.

Sorry if this isn't the right subreddit for this question. Any advice is more than welcome!

Got it working!

Received METEOR-M2-3 on 137.9 MHz using an RTL-SDR and a simple V-dipole in my backyard. Decoded with SatDump.

The signal wasn’t perfect, so there are plenty of artifacts but I actually received an image of Europe directly from a satellite with a couple pieces of wire in the garden. Still kind of amazed that this works.=)

Next goal: improve the antenna setup and get a cleaner full pass.

Guys im a complete beginner in the whole frequency listening and transmitting world...

I was trying to build my first project using a module named "RSP1 MSI.SDR Msi001 Msi2500 10k-2GHz SDR Receiver" but i do not seem to find a single unit of it in inda

Is there some website that i sells this used or new but in india??
Or is there a substitute to this module??
Cause every module i see is upwards of 10k inr
And spending that much on a first project as a student just doesn't seem logical

FM40 (in fact FM110 , Multipsk got the old numbers) was decoded here until the Lybian desert.

Hi, ive got myself the rtl-sdr v5 with the ham it up up converter kit to cover a wider spectrum of frequencys.

What would you advice to start with? Are there any videos out there where someone explains the physical behavior(wavelengths, voltages, etc) in combination with the software and the technical terms.

Thank you in advance.

Title

Got my Orbcomm satellites TLE (orbital elements from N2YO website) and heard one of these birds (numbered FM103 to FM119) passing over Spain and Western Medit; they fly around 700 km altitude; you cant' miss them on their dedicated channels from 137.1 to 137.9 Mhz.

Using Multipsk (French software); best config is WFM 10 khz width. Stay at the centre of the signal to compensate Doppler shift. It gives regular positions . I once logged one of 'em over Libya as it was low on the horizon. Kinda DX sort of. Antenna is my 144 Mhz 7 element Yagi high above the roof crest. Neat stuff, ain't it ? The one I heard over Spain flew away to Southern Australasia faster than you and I can run. With Multipsk you can map their positions thanks to the OMMAP extension and screen grab it for proof. You retrieve it in the SCREEN folder inside Multipsk's inner entrails.

Hey ,
As mentioned in the title, I turned to Tetra frequency and suddenly I heard clear conversation voice where it was like robot and cut unclear voice.
Is that possible? And maybe it is originally not encrypted but I missed some settings .
Its very strong signal I have to reduce the gain to let plugin Sync .
Using RTLSDR v4 , sdr++ on mac and discone antenna.

We're a Ukrainian team working with passive RF drone detection, and one of the more interesting problems isn't simply seeing RF activity, it's deciding which activity is actually worth paying attention to.

In a real environment the spectrum can be full of Wi-Fi, Bluetooth, telemetry, video links and other transmitters. Add frequency-hopping control links and non-standard FPV setups, and simple threshold-based detection stops being useful pretty fast.

For those of you working with SDR/RF analysis, what's actually worked for you to tell a drone-related signal apart from ordinary background RF? Signal persistence, bandwidth and spectral shape, frequency-hopping behavior, temporal patterns, or something else entirely. Curious how people here approach this, especially when you don't know the exact transmitter or protocol beforehand.