There are several levels to contribute at but the ideal contribution is the ‘Voter’ level at $50 USD. By contributing to the fundraiser at the ‘Voter’ level you will be able to have a vote on what features are to prioritized. It is also possible to contribute at a lower level of $10 USD and forego the voting perk.
The list of features to be implemented and the voting system can be found at igg.kmkeen.com. Important improvements will be made to the librtlsdr library, rtl_sdl, rtl_adsb, rtl_tcp, rtl_power and rtl_fm..
We hope that if you have enjoyed the RTL-SDR in some form you will contribute to this developer and help make this hobby an overall better experience.
Over on YouTube user Guilherme Dattoli Cirigliano Cortes has uploaded a video showing his use of the RTL-SDR in some MATLAB based cognitive radio experiments. Cognitive radio is a upcoming technology which aims to increase radio spectrum use efficiency by finding and using the intermittent periods of unoccupied frequency space.
The uploader explains his task below.
The fundamental task of each Cognitive Radio (CR) user in CR networks, in the most primitive sense is to detect the licenced users, also known as primary users, if they are present and identify the available spectrum if they are absent. This is usually achieved by sensing the RF environment, a process called spectrum sensing. Here we use one of the technique of spectrum sensing called energy detection.
The ISEE-3 is a exploratory spacecraft that was launched in 1978 and placed in an orbit around the sun. It was mission was to study the interaction between solar wind and the earth’s magnetic field and was later the first spacecraft to pass through the tail of a comet. NASA suspended communications with the spacecraft in 1997 and it was last heard of in 2008.
Recently there has been interest in rebooting the spacecraft and bringing it back into an earth orbit. Once safely in orbit the spacecraft’s science instruments would be made publicly available for educational purposes. Unfortunately, the RF communications hardware and knowledge that was used to interface with the spacecraft has long been lost.
Amateur radio astronomer Y1PWE has uploaded a pdf document describing how he created a low cost hydrogen line telescope using an RTL-SDR dongle. Hydrogen atoms randomly emit photons at a wavelength of 21cm (1420.4058 MHz). Normally a single hydrogen atom will rarely emit a photon, but since space and the galaxy is filled with many hydrogen atoms the average effect is an observable RF power spike at 1420.4058 MHz. By pointing a radio telescope at the night sky, a power spike indicating the hydrogen line can be observed in a frequency spectrum plot.
Y1PWE created a radio telescope using a quad 22 element yagi antenna, several LNA’s and filters and an RTL-SDR dongle and laptop. Using this setup he can capture some raw IQ data from the RTL-SDR and then use an FFT averaging program to produce some plots. In his plots the hydrogen line is clearly visible.
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.
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.
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.
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)