A few days ago we posted about the release of Rpidatv, a program that allows a Rapberry Pi to transmit DATV without the need for any additional hardware. DATV stands for Digital Amateur TV, and can be received with an RTL-SDR using a program called leandvb.
Over on YouTube, the programmer of Rpidatv (Evariste F5OEO) has uploaded a video that shows a Rpidatv + leandvb system in action. The video demonstrates the touch screen GUI which can be used if a touch capable LCD screen is connected to the Raspberry Pi. It also shows the whole system in action with a video being transmitted from the Raspberry Pi camera to a Linux PC with an RTL-SDR running leandvb.
rpidatv with leandvb
Another video uploaded to YouTube by Qyonek also shows Rpidatv + leandvb in action.
Over on the SWLing Post blog contributor Mike Ladd has posted up a review of the Soft66RTL3 software defined radio. The Soft66RTL3 is a fully enclosed SDR unit that consists of a standard mini RTL-SDR dongle, a selectable upconverter circuit, several switchable bandpass filters for HF and a UPC1688 RF amp which is enabled in HF mode and is controllable through a trimmer pot. The selectable bandpass filters are from 0.4 MHz to 1.2 MHz, 1.2 MHz to 5 MHz, 5 MHz to 15 MHz and 15 MHz to 30 MHz. The unit also comes enclosed in an aluminum box with an SMA input connector and Micro-B USB port.
The Soft66RTL3 is custom produced by Kazunori Miura (JA7TDO) who is based in Japan. The Soft66RTL3 sells for $40 USD shipped, or $46 USD shipped with registered air mail.
In the review Mike shows us the insides of the Soft66RTL3 and discusses its features. Later he also shows an installation and user guide.
Akos from the RTLSDR4Everyone blog has recently come out with a new post where he explains how to get the best ADS-B reception with an LNA and filter. In his experiments he uses an LNA4ALL low noise amplifier and and ADS-B Filter, both of which are sold by Adam 9A4QV. New versions of the filter sold by Adam now also include a built in bias-tee circuit which allows you to easily power the LNA4ALL over the coax cable, allowing you to place it externally.
In the post Akos shows where to optimally place the LNA and how you can use your Raspberry Pi together with the ADS-B filter with bias-T in order to power an antenna mounted LNA4ALL. The post also discusses what the cheapest solution is for European customers attempting to optimize their ADS-B reception.
ADS-B Setup including a filter, bias tee, LNA and Raspberry Pi.
F5OEO writes that the software is capable of generating a symbol rate from 64k symbols to 1M symbols, which is enough to transmit one video with good H264 encoded quality. He also writes that using a low symbol rate may be useful for long distance transmissions as the signal will take up a smaller bandwidth. For example a 250K symbol transmission would only need 300kHz of bandwidth. He writes that this type of transmission could easily be used in the ISM band to replace WiFi video for FPV, but that at the moment video latency is about 1 – 2 seconds and is still being improved.
Once again we remind you that if you intend to transmit using these methods where a GPIO pin is modulated, then you MUST use a bandpass filter at the frequency you are transmitting at, and that you must be licensed to transmit on those frequencies.
A DATV transmission received from a Raspberry Pi transmitter.
Over on YouTube user London Shortwave has uploaded a video showing a comparison of the FunCube Dongle Pro+, Airspy with SpyVerter upconverter and SDRplay on shortwave reception. The Funcube, Airspy and SDRplay are all $150 – $250 USD software defined radios that have much higher performance compared to the RTL-SDR.
In the video he tests the reception of Radio New Zealand International (RNZI) at 9400 kHz using a 6m copper wire dipole and 9:1 matching balun raised 2m off the ground. He did not use any external antenna preselectors. The RNZI station is weak and appears to be almost blocked by a stronger station so reception of the station is difficult.
In his results it appears that the FunCube and Airspy/SpyVerter are able to clearly receive the RNZI station, but the SDRplay has trouble with images of other stations mixing into the signal.
Recently RTL-SDR.com reader Neil KM4PHK wrote in to us to let us know that he’s been having a good time searching for SDR related PCB’s over on OSH Park. OSH Park is a company that allows you to upload and share a PCB, and then have it cheaply printed and sent to you for construction.
Over on YouTube user Tobias Härling has uploaded a video showing how he used a Raspberry Pi and RTL-SDR dongle to set up an AIS receiver. AIS stands for Automatic Identification System and is a radio system similar to ADS-B which allows you to create a radar-like system for boats. For Windows we have a tutorial on AIS reception here.
In his setup he uses rtl_ais and the kplex software and shows how to install everything from scratch. He also shows how to set the system up so that decoding automatically starts up and begins outputing NMEA data through the network when the Raspberry Pi is powered on. This way an a device like an iPad could be used to run OpenCPN to view the plotted ships.
Partial discharge is the situation in which electricity arcs through an insulating dielectric material when high voltages above the rated voltages for the insulator are applied. Continued partial discharge can cause the insulator to eventually be destroyed and fail, potentially causing catastrophic failure.
Partial discharge can be detected using a spectrum analyzer to monitor the spectrum for noise signatures associated with a discharge. Using a program written in MATLAB to make the RTL-SDR act as a spectrum analyser they show that the measured spectrum can be used to detect when partial discharge is occurring and that the results are similar to a more expensive spectrum analyzer.
Lab set up for using an RTL-SDR to detect partial discharge.
