Over on YouTube claudio giuliani has posted a video of his RTL-SDR Wide Spectrum Analyzer software. The software is written in the basic for gambas language and uses an RTL-SDR software defined radio to plot a wide chunk of the frequency spectrum by sweeping over it. It looks to be similar to the RTL-SDR Scanner software. Currently it is only available for Linux.
Programmer Tyler Watt has been working on software that automatically logs each call from an RTL-SDR running DSD (Digital Speech Decoder) and then stores it in a time stamped database as an mp3 file. There is also a web front end for the database which allows public users to search and play recorded calls.
Recently Tyler updated his code by rewriting it in PHP and making it multiplatform.
The old version of his web front end in action for his local P25 calls can be viewed here, and the newer one can be found here.
Radio controlled electricity power outlets are outlets that can be turned on or off using a wireless radio controlled remote. Over on the blog leetupload.com the author has written an article showing how he was able to reverse engineer the wireless power outlets radio protocol.
The author used an RTL-SDR and SDR# to listen to the outlets wireless AM transmissions at 434 MHz. He then recorded the signal audio and then used audacity to view the waveform. By analyzing the audio output he discovered that the signal was a Non-Return-To-Zero (NRZ), pulse width modulated (PWM), Amplitude Shift Keying / On Off Keying (ASK/OOK) signal.
Later he was also able to use the RFCat USB dongle to transmit an on off signal from his computer. RFCat is an USB dongle that is capable of transmitting on 433 MHz.
Akos from the SDR for Mariners blog has posted an article that highlights the effects of coaxial cable attenuation. Long runs of coaxial cable between the antenna and RTL-SDR can significantly attenuate signals. This means that strong signals at the antenna will become weak signals at the receiver. The solution to this is to either reduce the cable length or to use higher quality cable. A preamp like an LNA may also help to overcome long runs of coaxial cable. Akos’ article discusses these issues.
There are now some custom RTL-SDR kits available from Chinese and Russian manufacturers. These kits are essentially the standard RTL-SDR laid out on a custom PCB with extra upconverter (or direct sampling) circuitry on board.
This is a 100 KHz to 1 GHz RTL-SDR kit (~$23 USD), and this is another 100 KHz to 1 GHz pre made custom RTL-SDR in a nice box (~$40 USD) (alternative Chinese seller). The Chinese sellers page shows some examples of the performance on Youku (Chinese YouTube)
Over on YouTube user k2nccvids has posted a video showing how he was able to decode APRS signals and plot them on a map using APRSISCE32. APRSISCE32 is an advanced Automatic Packet Reporting System (APRS) decoder which has mapping capabilities and can also connect to the internet as an iGate. APRS is used by amateur radio hobbyists to send data like messages, announcements and also GPS coordinates.
Over on YouTube user taroz1461 shows real time GPS positioning done in software using a BladeRF. The BladeRF is a ~$400 software defined radio which similar specs to the HackRF and compared to the RTL-SDR is capable of receiving much larger bandwidths and transmitting.
To do this decoding he used RTKLIB and his own GNSS-SDRLIB software which is a Windows GUI program. We aren’t sure if this software will work with the RTL-SDR, but we note that other people have had success with GPS positioning and the RTL-SDR.
Over on YouTube Adam Alicajic has posted a video showing how much a bandpass filter at the front end of an RTL-SDR can significantly improve reception. He points out that it is a myth that modern software receivers do not need preselector filters at the front end for best performance.
He tests the RTL-SDR with and without a front end 2m triple helical bandpass filter on a CW beacon at around 144 MHz. With the filter on there is almost a 10dB improvement in signal reception.
