Questions tagged [rtl-sdr]

Discussion related to the rtl-sdr project, which enables certain television dongles and other hardware to be used as a cheap SDR receiver

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How to fix correlator memory allocation error in GNSS SDRLIB while post processing?

I am using GNSS SDRLIB for postprocessing a RTL SDR signal sample and as you can see I was able to get the acquisition of the satellites, however I'm not getting any position fixes (the obs file is ...
darkmatter's user avatar
1 vote
1 answer
98 views

Signal Patterns on Waterfall are not Same for Two RTL-SDRs

I have two RTL-SDR Blog v3 dongles which are connected to same antenna with an antenna splitter. Steps that I follow: Connect them to a PC and run two gqrx instances Set 2.4Msps sample rate for both ...
mob's user avatar
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2 votes
0 answers
105 views

Receiving a lot of noise with RTL-SDR and SDR# for GOMX-1

Hi im new to SDR and having issues setting up SDR#. I'm trying to receive from GOMX-1 on 437.25 MHz for a project. My set up is the dongle, a LNA and a self built helical antenna for that frequency's ...
Rob's user avatar
  • 21
3 votes
3 answers
145 views

Why can a monopole antenna receive wavelengths significantly longer than its physical length?

I am new to ham radio and have been playing with a RTL-SDR receiver to which I have connected a vertical 1.5m monopole antenna. However, I can receive transmissions belonging to the 40m band (albeit ...
Fabián Iglesias's user avatar
1 vote
1 answer
158 views

What type of metal, length & diameter should i use to build a vertical antenna to listen to airband frequencies (118-137Mhz)?

I recently purchased RTL-SDR v3 dongle along with antenna kit. I used 60cm each length and built vertical dipole antenna with boom length of 58cm and listened to airband frequencies.The closest ...
Krishna Kanth's user avatar
1 vote
1 answer
357 views

Why is the Air Band distorted at times with SDR Sharp?

I am using SDRsharp to monitor air band with an RTL-SDR dongle. Sometimes I receive ATC voice clearly but at times it's distorted, I am using RTL AGC gain of 29dB with no tuner gain. My filter ...
user3696623's user avatar
0 votes
1 answer
164 views

Descrambling/dewhitening in GNURadio

I am currently working on project which utilizes RTL-SDR for capturing packets. I know that those packets are whitened with x^9 + x^5 + 1 polynomial. No matter what I do the descrambling each time ...
Artur's user avatar
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What is the point of using LNA if the SDR can increase the gain itself [duplicate]

Usually there is a LNA next to antenna, while SDR devices also have gain setting so we can increase the gain. As i know LNAs are amplifying all signals with same gain (Am I right?) So i wonder what is ...
Ariyan's user avatar
  • 143
0 votes
1 answer
58 views

Chaining multiple coaxial adapters

I want to connect an RTL-SDR dongle that has an MCX Female antenna port to an N-Type Male antenna feedline. I know there are thousands of pigtails and adapters for every possible need, seemingly ...
5eleven7's user avatar
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1 answer
706 views

Why can't I get the radio/waterfall to show in SDRAngel - GQRX works fine

I was wondering why the digital decoder in SDRAngel wasn't working, but now I see that even broadcast FM isn't showing a bump in the spectrum: I can play broadcast fm radio stations (the ones playing ...
NoBugs's user avatar
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1 vote
3 answers
476 views

What can be used to protect an SDR receiver against bursts?

I am using a USRP B205 to detect electromagnetic pulses. Sometimes the signal power bursts to 100 dB, average power is around 10 dB. What can be used to protect the SDR receiver against bursts?
kittygirl's user avatar
  • 600
5 votes
2 answers
783 views

Eliminating RFI from raspberry pi

I am trying to eliminate RFI coming from a raspberry pi 4. The Rtlsdr(enclosed in a metal case) is directly plugged into the pi without any USB extension cable. The frequency of interest is at 1420....
radastro's user avatar
7 votes
7 answers
10k views

Why is 20m band waterfall showing signals every 50 kHz?

I'm very new to shortwave listening and just got to grips with my RTL SDR HF dongle. Last night while on the 20m band, there were signals exactly every 50kHz, starting exactly at 14.000MHz, then at 14....
rcx935's user avatar
  • 401
2 votes
1 answer
285 views

How do I choose between T37-2 vs T37-6 for this High-Pass Filter?

My RTL-SDR V3 is being overloaded by an AM broadcast so I'd like to build a high-pass filter to block the AM broadcast band. I thought I'd start simple and try making the one shown in Fig 3 of "...
Bezewy's user avatar
  • 153
3 votes
3 answers
2k views

How to increase the range of the spectrum analyzer in SDRSharp?

I'm trying to visualize the frequency band utilization during a GSM phone call using SDR. Ideally, I would like to plot the whole 900 MHz range, i.e. 876-959 MHz. However, even setting the zoom to the ...
Dmitry Grigoryev's user avatar
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1 answer
132 views

How to analyse the distribution of the noise being received by my RTL-SDR device?

I'm very new to RTL-SDR and signal processing in general, but have managed to get my device (NOOELEC NESDR Mini) working and data into Python (via the pyRTLSDR library). I am able to output a complex-...
Kris's user avatar
  • 101
0 votes
1 answer
249 views

How to get the "real" number of samples coming in an sdr

so I am fairly new to this SDR and dsp thing, I am working on a project that calculates the ppm and adjusts the offset, now I kinda got the idea of how to calculate the ppm after going through the ...
RasenRhino's user avatar
5 votes
1 answer
337 views

Failing to detect Hydrogen line with 105cm dish

I've seen many examples of roughly 1 metre sized dishes being used w H+ sawbird and an SDR to detect and analyze Hydrogen line signal, and have been trying myself but can't seem to get anything beyond ...
Jack_SH's user avatar
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0 votes
2 answers
77 views

Not able to understand some operations in rtlsdr library in python

Here is the part of the program I am having problems with: samples = sdr.read_samples(16*1024) power, _ = mlab.psd(samples, NFFT=1024, Fs=sdr.sample_rate /1e6) ...
RasenRhino's user avatar
4 votes
2 answers
775 views

Problem with sample rate

So I am working on a project that involves me to check real time difference between samples.I am fairly new to this so after a bit of researching I wrote a simple python script for it, here is the ...
RasenRhino's user avatar
0 votes
2 answers
306 views

How do I set the RX frequency on a R820T/ R820T2 based SDR

My question relates to the specific programming of an R820T/ R820T2 based SDR for a specific frequency. I'm trying to build a self contained and auto initializing Raspberry Pi 4-based (ignore that ...
BigNutz's user avatar
  • 101
1 vote
0 answers
479 views

GNU Radio FM Receiver does not work on Ubuntu 20.04 nor on Windows 10

GNU Radio v3.8 with Qt-GUI on Ubuntu 20.04 Before starting on something new I always test my setup with this GNURadio hello world flow graph which I know for sure, that it used to work. The other day, ...
Duck Dodgers's user avatar
2 votes
1 answer
499 views

Heterodyning complex values in gnuradio

I have been working at educating myself on how SDR and GNU Radio works. In order to demonstrate heterodyning, I set up a flow-graph consisting of 2 signal generators, a Multiply block, and QT GUI ...
KevinHJ's user avatar
  • 215
4 votes
2 answers
1k views

rtlsdr - hearing an FM broadcast on different frequencies

There is an FM station in my city which transmits at 105 MHz. Today I discovered that I can also hear it quite well if I set the LO to 32.6 MHz and then shift the signal a bit. I'm using an rtlsdr ...
Ardavast Dayleryan's user avatar
1 vote
0 answers
329 views

Capture Uplink GSM packets using 820T2 and SDR

I am an extreme beginner with SDR. I am trying to use the 820T2 & SDR device to capture uplink gsm packets sent by my phone to the nearest Base Station. I have an Rx Monitor App installed on my ...
anonymous's user avatar
1 vote
1 answer
706 views

Adapt old AvermediaTV DVB-T tuner as SDR

I want to adapt the DVB-T AverMedia TV Pilot" tuner as a software defined radio, but it is not built on a RTL chip, so the question arises, is there some kind of driver to use my tuner as a radio?...
Антон's user avatar
2 votes
2 answers
463 views

Broadcast signal deviating with time

I've been just scanning through the HF band at night seeing what all I can pick up, and I'm trying to figure out a particular signal. I'm using a VHF discone, which isn't ideal, but it works well ...
directedition's user avatar
4 votes
1 answer
170 views

How to track down and neutralize this apparent mixer creating noisy emissions around my signal?

When I transmit, it there seems to be something mixing and reflecting my signal. For example, when I transmit on 14.300 MHz, I see signals above my transmitted signal at at 14.500, 14.700, 14.900, etc....
Rosa's user avatar
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0 votes
1 answer
893 views

Implementing FM receiver using GNU Radio C++ API

This is my first ever experience with GNU Radio. I am trying to implement a simple FM receiver shown below with its C++ API. I seem to have pedantically deconstructed this receiver into its smallest ...
Oleksandr Kravchuk's user avatar
2 votes
3 answers
815 views

Problem with RTL-SDR v3 dongle - unusable PLL

I own an RTL-SDR v3 USB dongle (official version from rtl-sdr.com). I've successfully used it for decoding weather satellites past year. I use (GQRX + Audacity)/(Arch Linux 64bit) + (WXtoIMG)/(Windows ...
Drobot Viktor's user avatar
0 votes
1 answer
650 views

GNURADIO: What does the complex output of an osmosdr source translate to?

Warning: Noob question. I'm new to Software Defined Radio. My aim is to write a program that tells me the signal strength of a radio emitting source (I'll use three such sources and then try to ...
mathemagician's user avatar
3 votes
2 answers
447 views

HDMI to VGA adapter interference with 138.5 MHz carrier

(sorry for my English) I'm using the HDMI to VGA adapter on my pc, and receiving weather satellites on ~137 MHz with RTL-SDR V3. There was a problem: my VGA adapter creates a powerful signal, who ...
lethanner's user avatar
2 votes
1 answer
291 views

How is gqrx producing audio?

How exactly is GQRX converting signal in any frequency to produce audio output? Is it actually done by gqrx or some other element of the stack?
Łukasz Zaroda's user avatar
1 vote
1 answer
115 views

Ham radio listener is split up on old hardware

I'm trying to get a ham radio listener working with RTLSDR on an old Pentium 4. Unfortunately it is playing for a few seconds, then not playing for a split second, very split up. Is there a way I can ...
NoBugs's user avatar
  • 241
3 votes
2 answers
848 views

Can I use a “bunny ears” TV antenna for RTL-SDR?

I'm trying to get into SDR and was planning on buying an RTL-SDR. For an antenna, I was thinking of using an old set of bunny ears I have lying around. However, I first want to make sure that they'll ...
genghiskhan's user avatar
7 votes
4 answers
2k views

DIY SA612 + RTL-SDR HF receiver: good on laptop, but huge wideband noise on Raspberry Pi

I recently built a SA612 mixer for HF reception. I used an USB-frequency oscilator to shift the incoming frequency up by 28.8 MHz. I used a random wire antenna outside my balcony and connected it to ...
比尔盖子's user avatar
1 vote
2 answers
102 views

Batch sampling SDR

I am using RTLSDR on macOS with Cubic SDR, it works great and is very intuitive. Now I want to do a frequency envelope analysis where I need to basically 3-d plot intensity versus frequency and time. ...
William Entriken's user avatar
1 vote
0 answers
406 views

Compare signal strength with Software Defined Radio

I want to compare field strength with an RTL-SDR dongle or HackRF One. With comparing I mean being correct relative to one another, like if I know field strength of one in mW/m^2 then I know the other....
Peterilu's user avatar
4 votes
2 answers
368 views

Demodulating ISO14443 (part of NFC) using SDR?

I'm looking for info on demodulating both sides of an ISO14443 communication using a cheap SDR, preferably an RTL-SDR (R820T2+RTL2832U). The application is passively monitoring an NFC exchange for ...
fgrieu's user avatar
  • 141
0 votes
1 answer
382 views

Using dvb-t device as rtl-sdr

I am wondering if I can use that dvb-t device to listen 48-836 mhz? if it's no, why? thanks..
gks's user avatar
  • 1
2 votes
1 answer
2k views

how to select an SDR stick remotely from gqrx via soapysdr

I have a raspberry pi 3b on my roof (in a plastic box) with two SDR sticks attached to it. On the raspberry pi the "soapysdr" program runs. ...
Folkert van Heusden's user avatar
1 vote
0 answers
845 views

Capturing Bluetooth / WiFi on an SDR

I have a question, right before purchasing SDR for some tests: Commercial hardware for bluetooth (even Ubertooth) allows you to receive packets on a 1MHz channel. Which practicaly means that if you, ...
Jentel's user avatar
  • 11
1 vote
2 answers
5k views

GNU Radio does not run flow graph

I am sorry but yet again a question about GNU Radio. (I just started following some tutorials a couple of months ago and am learning about it. I am unfortunately not that proficient in it yet, but I ...
Duck Dodgers's user avatar
1 vote
2 answers
1k views

How much power does an RTL-SDR draw?

Background: Last night (and the night before) I was playing with my RTL-SDR and GNU-Radio again. Working with my FM Receiver, (which was working previously by the way), I detected that last night I ...
Duck Dodgers's user avatar
1 vote
2 answers
231 views

What to take in consideration when buying an RTL SDR dongle? (Amateur)

I want to buy an SDR RTL USB dongle and I'm looking for one on Amazon. I currently saw ones from 100 MHz to 1.7 GHz. I can't decide and I know almost nothing about radio, but I want to experiment ...
Lorthas's user avatar
  • 141
0 votes
0 answers
268 views

No module named 'analog_swig' [duplicate]

I know guys you gonna tell me tat there is something wrong about GnuRadio or Pybombs installation. Well, this is my third time during the past 48 hours I reformat the OS of my mini pc fitlet2 mint ...
Hadad's user avatar
  • 325
0 votes
0 answers
170 views

No module named _osmosdr_swig [duplicate]

I am trying to run GnuRadio python code in my python web server and got the "No module named _osmosdr_swig" error. Please, what is the cause for this error? I know it sounds like so obvious that I ...
Hadad's user avatar
  • 325
2 votes
3 answers
1k views

VHF 50 Ω Antenna Over 75 Ω TV Coax

I have a 50 Ω VHF airband antenna which I’m planning to install in my loft, for use with a RaspberryPi-based RTLSDR scanner/receiver. I already have a UK-standard UHF/Freeview antenna using standard ...
Craig Watson's user avatar
3 votes
0 answers
224 views

HackRF One and IoT overloaded?

I'm transmitting Z-Wave frames using HackRF One in loop, one frame every second. Has anyone clue why are some frames not transmitted? You can see several too long gaps between frames on Waterfall (...
Simon Štefunko's user avatar
1 vote
1 answer
269 views

Unitrunker Receivers Not Displaying Fields

I've been playing around with RTL-SDR and Unitrunker attempting to get a police scanner working. I followed the tutorial here: https://sites.google.com/site/policescannerhowto/ Everything works as ...
shenk's user avatar
  • 113