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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19
votes
5answers
8k views

SDR: Quadrature demodulation vs direct RF sampling

I see that many SDRs use a quadrature demodulator and sample I and Q signals. But is it possible to downconvert the RF signal instead, sample it with only one ADC, and get the same capabilities of ...
10
votes
1answer
355 views

Confusion about SDR

I've just written code for the RTL2832 to receive and decode ADS-B packets (very cool!). I had some confusion about what is actually happening: Is the raw data coming from the USB dongle literally ...
10
votes
2answers
728 views

Can an amateur use cellular technologies with SDR?

Software Defined Radio is opening up many new possibilities for amateur digital modes. One family of technologies that interests me is cellular. 2G GSM voice/sms and 2.5G GPRS data has been proven to ...
9
votes
3answers
1k views

AIS and RTL-SDR Dongles

I am looking for an Windows-based AIS Decoder for RTL Dongles. Currently, there is a solution available using GNU Radio and SDR# but it is complicated to set up and keep running. ADSB has a dedicated ...
9
votes
3answers
14k views

How can I reduce the noise coming in from an RTL-SDR dongle?

I've recently received an RTL-SDR dongle, and I'm picking up a lot of noise that is probably coming from my PC, especially a lot of "spikes" on the 2M band. I've already started using a USB extension ...
9
votes
1answer
349 views

Why do SDR control apps have two frequency settings?

Why do many SDR control apps have two frequency settings, even when the app is designed or set up only for listening to or decoding one signal? Should the two SDR frequency controls be set ...
8
votes
1answer
7k views

How to choose the right sampling rate and bandwidth for RTL-SDR dongle?

Receiving the frequency of 97.9 MHz I have a Terratec SDR dongle and I am trying to capture a radio frequency. The FFT window shows the frequency range from -500 to 500 KHz. Is there a way to ...
7
votes
3answers
3k views

Using an RTL-SDR as a spectrum analyzer

I've been trying to get into RF electronics, but one thing that is holding me back is lack of test equipment. I have an old analog oscilloscope, but that doesn't help much for things like verifying ...
7
votes
4answers
743 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 ...
7
votes
1answer
592 views

How to make a ferrite bar antenna for RTL-SDR?

I bought a RTL-SDR (blue one with little MCX antenna). I modified its Q branch, and can receive short wave radio with Degen 31MS antenna now. For MW, Degen 31MS antenna has a ferrite bar antenna ...
6
votes
2answers
385 views

Advantages of IQ generation at Mixer Stage or within FPGA for SDRs

I draw two possible architectures for Software Defined Radios below. In the first architecture, I,Q signals are generated at the mixer stage and two ADCs are required. The FPGA down-samples the ...
6
votes
1answer
937 views

Cell Tower distance measurement

I am developing a hobby project to detect/measure the distance between my cell phone and a cell tower (GSM tower). I am newbie. I don't even know whether this is possible or not. I have following ...
6
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1answer
2k views

RX antenna and RTL SDR with upconverter ..How to hear something?

I mounted a small RX antenna (mini whip, bought from eBay) (on 10-th floor) and I want to try to listen to something. I bought a RTL-SDR with Upconverter which supports HF. RX antenna's operating ...
6
votes
1answer
590 views

SDR - FM Radio station interference

I want to learn about software defined radio and how wireless transmission work in general. So I started messing around with SDRSharp and a little antenna I bought. I figured I would start looking ...
6
votes
1answer
819 views

Video transmission between ATV and SSTV

I'd like to experiment with amateur video transmission in a setup halfway between ATV and SSTV. 480 lines of B&W image would be sufficient with 10 FPS, and I'm interested in both digital and ...
6
votes
1answer
2k views

How to detect a tone on an FM Frequency using an RTL SDR receiver?

I'm transmitting a simple tone which lasts 50 ms using an FM transmitter. I can see clearly this tone being received on my RTL-SDR device when I look at a spectrum graph (using GQRX). I need to call ...
6
votes
1answer
697 views

What should I look for in an antenna for a DVBT Dongle used for SDR?

I use a cheap DVBT dongle that I control via RTL-SDR. Right now a very basic setup. The general consensus seems to be that a long usb cable should be used (to keep noise from the computer away from ...
5
votes
5answers
2k views

How important is the impedance and resonance of a receive antenna?

I'm very new to shortwave radio, as evidenced here: Can an antenna be too powerful for certain receivers? I want to build a longwire receive-only antenna for the HF frequencies. I've been using ...
5
votes
2answers
109 views

Digital transmission sounds

I'm playing with an RTL-SDR dongle and an LNA, on Linux Mint with GQRX and DSD A lot of frequencies show digital transmissions, which the DSD is not converting. I don't whether it is a format DSD ...
5
votes
2answers
3k views

How to determine the PPM value of a NESDR SMArt?

a) Given that I don't have a frequency standard or other known transmitter available, what is the easiest way to calibrate the NooElec NESDR SMArt which is using a TCXO rated at 0.5 PPM.? I.e. to ...
5
votes
3answers
1k views

Noise & shielding, SDR Dongle

First, I'm very new to SDR. This may turn out to be really obvious. I just want to verify my thoughts before I spend more dollars. I have a USB dongle with the RT28xx in it. Works great. Side by ...
5
votes
1answer
227 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 ...
5
votes
1answer
192 views

Images up and down the spectrum

I brought an rtl-sdr USB stick to a foreign country. I am listening with gqrx, and I am surprised to find audio (e.g. television or radio) up and down the spectrum, up to 600, 700 and 800 MHz ranges....
5
votes
2answers
8k views

How to play spectrum recordings made with rtl_sdr in gqrx?

I have an R820T DVB dongle and the rtl_sdr software on a linux computer. I can listen to various frequencies using the gqrx software which uses the rtl_sdr library as a device driver for the USB-...
4
votes
2answers
323 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 ...
4
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1answer
3k views

Why doesn't GNU Radio Companion's wx Constellation Plot doesn't give me the clean QAM constellation I get from its Qt sibling?

Using a RTL2832U USB dongle, I set up GNU Radio to produce a constellation plot of APRS traffic on 144.8 MHz. The result is what I expected: So far, so good. Why not try the same thing using the wx ...
4
votes
1answer
84 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....
4
votes
2answers
6k views

Where can I find a listening guide for different frequencies and their usages to listen to on SDR?

I just got an RTL-SDR dongle by Nooelec and am using CubicSDR on Mac (which supports AM, FM, and SSB), and I'm in Canada. I'm able to easily find FM radio stations, but outside of that I'm not sure ...
4
votes
1answer
1k views

SDR with the Raspberry Pi

I wanted to explore digital modes by connecting a Raspberry Pi via audio cables to a transceiver. However, I realized that thanks to the clock generator, the raspberry pi can produce RF signals ...
4
votes
1answer
967 views

FM Receiver on GNU Radio with RTL-SDR fails to produce any output sound

Here is how the FM Receiver I made using the GNU Radio Companion. (Basically, I was following this tutorial by VYE6Y on youtube.) FM Receiver Problem: Unfortunately for me, the GNU Radio gives no ...
4
votes
1answer
497 views

ADS-B for Trains?

Is there any kind of technology similar to ADS-B for trains? I'm aware of HOT/EOT/DPU messages, but as far as I can see these don't allow you to see its location. I'm specifically wondering about the ...
4
votes
1answer
2k views

Installing cuSDR on Ubuntu 13.04

I've been trying to install cuSDR64 on Ubuntu so as to have a 4-receiver 4-display SDR setup. I found the Windows repository on svn here. But, it gives an error (check this question). The cuSDR home ...
3
votes
2answers
622 views

RTL-SDR dongle - what antenna should I use for APRS receive only?

I was following this guide to setup an iGate using an RTL-SDR dongle and a Raspberry Pi. It worked, and I have been able to test it by seeing some APRS packets from a separate transmitter (Arduino+...
3
votes
1answer
174 views

RTL SDR “dark region”

I'm new to RTL SDR, and I noticed there's a "dark region" (around 700-900MHz), and I haven't figured out why this is. My device's tuner is a Fitipower FC0012, where could I find the pinout and ...
3
votes
3answers
2k views

Improving VHF airband reception

I'm trying to receive VHF airband transmitted from a nearby airport via RTLSDR and having a hard time doing so. Obviously the stock antenna is useless in this situation. I tried building a quarter-...
3
votes
2answers
115 views

Tips for HF Antenna with house near AM transmitter

My back garden is very small - about 500sqft. I also live near an AM transmitter and requires an AM filter. I would appreciate some general tips on the best approach to receiving HF signals (Ham and ...
3
votes
2answers
259 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 ...
3
votes
1answer
338 views

How can I determine if out of band interference is affecting my AIS reception?

AIS I am receiving ship AIS messages. These are low power, digital messages periodically sent on two marine channels close to 162mhz. This frequency is surrounded by FM broadcast, weather radio, and ...
3
votes
1answer
417 views

What is this Morse code-like station?

I’m trying to identify this signal at 928.807 MHz. A sample of the raw I/Q from gqrx is here (9.2 MB, .wav, 48000 Hz) and this is the waterfall: I’ve tried decoding some common digital modes (...
3
votes
2answers
2k views

Where can I download NESDR Smart (NooElec) drivers for Mac OS Sierra?

Just bought this NESDR Smart USB dongle from Amazon in Canada. Wrote the company asking for drivers, but they sent links which didn't help. Anybody have a better place to download drivers for Mac OS ...
3
votes
1answer
611 views

How to connect this Active Antenna Loop and 100MHz Upconverter?

I have bought the two devices in the image. The 100MHz Upconverter with a SMA connector is used to upconvert HF/MF signal for RTL-SDR to demodulate. I found that there is signal from the antenna (...
3
votes
1answer
678 views

Receive antenna design for a small apartment

I am looking to make a simple receive antenna from some wire, and I have some questions about resonance. Being that this wire can only be so long (about 3 meters maximum, as it must fit inside my ...
3
votes
0answers
139 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 (...
2
votes
3answers
878 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 ...
2
votes
2answers
355 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 ...
2
votes
1answer
224 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 ...
2
votes
3answers
349 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 ...
2
votes
3answers
273 views

SDR for Spectroscope

I'm looking into getting a cheap SDR (perhaps the RTL-SDR RTL2832U) to use as a spectroscope, especially to test the frequency output of Baofeng radios. I currently have reason to believe that one of ...
2
votes
2answers
139 views

FFT showing evenly spaced signals when tuned to ~56 MHz down to 25.680

I'm running GQRX on Mac OS X 10.11.6 hooked up to an RTL-SDR dongle. I noticed when I'm tuned anywhere between ~56 MHz on down to 25.680 MHz I see evenly spaced signals on the FFT. But when I tune ...
2
votes
2answers
179 views

RF scanner w/ graphic output

I debated putting this question on the electrical engineering forum vs. here. I settled on here since I figured many of you amateur radio experts have probably wondered about this too. I am ...