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.
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.
Recently FlightAware released a new RTL-SDR dongle sold at zero profit at $16.95 USD. It’s main feature is that it comes with an ADS-B optimized low noise amplifier (LNA) built directly into the dongle. FlightAware.com is a flight tracking service that aims to track aircraft via many volunteer ADS-B contributors around the world who use low cost receivers such as the RTL-SDR. In this post we will review their new dongle and hopefully at the same time provide some basic insights to LNA positioning theory to show in what situations this dongle will work well.
FlightAware Dongle Outside
A good LNA has a low noise figure and a high IIP3 value. Here is what these things mean.
Last time we tried AISRec we found its performance to be very good, with it decoding more messages than other software we tried. The new version includes the following updates:
Added auto detection of devices when devices are plugged in.
Added the support for airspy. Allow selection of devices by serial number for rtlsdr dongles.
Added AISRec core 3.0. The new core is 2x faster than AISRec core 2.0.
Added one embedded multi-user TCP server. Any client works with AISRec should implement auto reconnection.
Added auto display of local IP for the TCP server.
Added one output to one serial port.
Added interactive changes of gain parameters for devices.
A few changes on GUI.
Added an icon for GUI. Users should reset the windows icon buffer to allow the display of the new icon.
In addition, while AISRec hopes to be commercial software one day, at the moment they are currently offering free registration. See their FAQ for information on registering for free.
