RTL-SDR Easy HF Dongle Mod

Over on YouTube user crookedninja5 has uploaded a video showing what he calls the “Easy HF dongle mod”. The mod involves soldering a wire from Pin 1 on the RTL2832U chip to the static protection diode near the antenna input. At the same time he also uses the modified RTL-SDR dll file for SDR# which enables the “no hardware mod” direct sampling mode.

Using this mod he is able to get decent coverage of 0 – 14.4 MHz.

SDR Shortwave Radio Mod "easy HF dongle mod"

Using an RTL-SDR to help open a Gated Community

Tomasz lives in a gated community, but as he doesn’t own a car he wasn’t given access to a gate remote control. This made it difficult for him to have friends who have cars visit him. So he decided to use an RTL-SDR to receive, capture, analyze the gate signal which is transmitted at 433 MHz and then copy the signal to use with his own homemade transmitter.

First Tomasz used his RTL-SDR with SDR# to capture a few sound files of the gate remote which transmits at 433 MHz. Then he viewed the sound waveform’s in Audacity, a free audio editing program. Just by looking at the waveform he was able to determine that the signal was On-Off Key (OOK) modulated and that each frame of the transmission was the same, meaning that no security scheme was used.

Next he wrote down the transmission parameters that he learned from his analysis and built a simple 433 MHz transmitter which he connected to a microcontroller. After programming his microcontroller to send a copied signal he was able to open the gate.

433 MHz Gate Remote Received on the RTL-SDR
433 MHz Gate Remote Received on the RTL-SDR

Making a Cheap Noise Figure Indicator with an RTL-SDR

Amateur radio hobbyists Frank Schmaling (DL2ALF), Wolf-Henning Rech (DF9IC) and Alexander Kurpiers (DL8AAU) have uploaded a pdf document containing slides which show how they made a cheap noise figure indicator using an E4000 RTL-SDR dongle. A noise figure indicator can be used to check the noise figure of various components used in RF applications.

The hardware of the device consists of an RTL-SDR, a MGZ 30889 preamp, a noise source, a 28V boost converter to power the noise source and a serial to USB converter to control the noise source. They also created their own custom software in C# to go along with the hardware.

Their results showed that this setup was comparable to a professional noise figure test set.

RTL-SDR based Noise Figure Indicator
RTL-SDR based Noise Figure Indicator
Noise Figure Indicator Software
Noise Figure Indicator Software

Receiving Russian Long Range Navigation System with an RTL-SDR, Upconverter and Mini-Whip Antenna

Over on YouTube user Mile Kokotov has uploaded a video showing his reception of the ALPHA Russian Long Range Navigation System on Very Low Frequency (VLF) in Macedonia using an RTL-SDR, Ham-it-up upconverter and a Mini-Whip active antenna.

Mile also uses a band pass filter and notch filter to improve the dynamic range of the RTL-SDR. Additionally, in the video he shows a comparison between a large delta loop antenna and the mini-whip active antenna which shows better performance by the mini-whip.

RTL-SDR on VLF (ALPHA Russian Long Range Navigation System receiving in Macedonia with MiniWhip)

Hak5: Using A RTL-SDR To Learn About The GSM Network Around You

The popular YouTube electronics channel Hak5 has uploaded a video showing how they analyzed GSM signals using an RTL-SDR, Wireshark and Airprobe. In their video they use parts of our analyzing GSM tutorial and explain and show visually how to set up all the software.

Using these methods they were able to receive GSM data from a base tower and see various system information.

Using A RTL-SDR To Learn About The GSM Network Around You, Hak5 1621

Update to the RTL-SDR Transmitting at 1270 MHz

In our previous post we featured a video by OH2FTG which showed an RTL-SDR transmitting at 1270 MHz. Now OH2FTG has written in to give us some more information about the RTL-SDR transmitter. He has done a short writeup explaining how it’s done on his website. It turns out that the RTL-SDR is actually capable of transmitting a FSK morse beacon using it’s leaky oscillator.

In the video, code written by another ham OH2EAT is used. OH2EAT’s code essentially changes the frequency on the transmitting RTL-SDR at up to 300 times a second using a modified driver. This is used to create a Frequency Shift Keyed (FSK) transmission.

The modulating transmitter code is not yet available as it is not yet ready for release. In the future OH2FTG hopes to build an amplifier to boost the signal output for further experiments.

New Signal Identification Guide Wiki: sigidwiki.com

We’ve recently created a new radio signal identification guide over a www.sigidwiki.com. This is a wikipedia styled site which is editable by anyone. We hope that some readers will make a contribution by adding new reference signals, fixing mistakes or identifying unknown signals. Any comments or requests about the page are also welcome.

You can still contribute known or unknown signals to rtlsdrblog__AT__gmail__dot__com and I will add them to the sigidwiki myself.

RTL-SDR Transmitting at 1270 MHz

Over on YouTube user oh2ftg has uploaded a video apparently showing an RTL-SDR transmitting a low power signal at 1270 MHz. His explanation as to how it is possible to transmit with an RTL-SDR is that the local oscillator in the RTL-SDR is leaky, so it can be abused as a low power transmitter.

We aren’t sure how he enabled the transmissions or if it even is transmitting a real signal or just noise, but we hope someone can let us know in the comments. At the moment we think its just noise which changes its tune as the oscillator tunes to different frequencies.

RTL-SDR Transmitting on 1270MHz

New AIS Decoder for the RTL-SDR: PNAIS

Over on our Forums  has told us about his recently released an AIS decoder called PNAIS which appears to directly connect to the RTL-SDR and decode AIS data. After decoding it then outputs the decoded NMEA data via UDP, which could then be received and used in map plotting software such as OpenCPN.

AIS is and acronym for Automatic Identification System and is a system used by ships to broadcast position and vessel information.

PNAIS Decoder

Receiving a VLF Transmission using a PC Soundcard

Over on YouTube user Alex swl has uploaded a video showing his reception of a Very Low Frequency (VLF) radio signal using a laptop running SDRSharp and a Chirio Mini Whip antenna connected directly to the laptop’s sound card input.

Every year on Alexanderson Day (this year on 29/06/2014) and some other days the Varberg VLF Radio Station in Sweden transmits a morse code message using a 1.9 km (1.2 mile) horizontal wire antenna at 17.2 kHz with callsign SAQ. Because the transmission frequency is so low, a standard PC soundcard can be used to directly receive the signal.

Alex swl was able to receive this signal in Italy.

VLF – SAQ transmission GRIMETON 29.06.2014 – Italy