Category: RTL-SDR

September 19, 2015

Modifying an Aluminium Case to fit into our SMA RTL-SDRs

Recently we started selling modified RTL-SDR units that came with a more sturdy and common SMA antenna connector and a TCXO temperature compensated oscillator. At the moment our dongles are enclosed in a plastic shell. One simple way to improve the performance of an RTL-SDR is to enclose it inside a conductive metal box. This helps prevent out of band interference from strong signals that may enter the device directly and not through the antenna.

At the moment we do not sell any metal enclosures for our SMA unit (but we are working on one). In the mean time one of our customers has been able to modify an enclosure made for the older style dongles with MCX connectors, to be able to fit our new SMA unit. To get the dongle to fit they simply file down the edges of the PCB and drill a new hole in the case to fit the SMA connector.

We note that for good performance with a metal case it is very important that the metal be conductive, and make a good electrical connection to the dongle’s ground. The case purchased was anodized aluminum, which is non-conductive. It is important to file down the coating to ensure a good electrical connection is made otherwise the case will not work.

Modifying an RTL-SDR aluminium case to fit our new SMA RTL-SDRs.

September 19, 2015

Changes to SDR#: Update to .NET 4.6, Linux support and new install procedure

SDR# (SDRSharp) is probably the most popular software program that is used with the RTL-SDR. It is free, fast and fairly easy to use.

SDR# is coded in C# and so runs on the Microsoft .NET runtime. SDR# has always used the 3.5 version of the .NET runtime, however recently the programmers have made the decision to upgrade the runtime used to the latest 4.6 version of .NET. For non-programmers this means that compatibility with newer operating system such as Windows 10 is enhanced, performance and stability is improved and that SDR# can now be run on Linux and OSX with Mono 4.0. The downside is that Windows XP and Vista are no longer supported operating systems (Vista SP2 is supported). An OS compatibility list for .NET 4.6 can be found here.

If you are an SDR# user and run an older operating system such as XP or Vista we suggest that you either upgrade your OS, or simply continue to run the older versions of SDR#.

In addition to the new changes, the install procedure has also changed. Firstly, the old sdrsharp.com website now redirects to airspy.com. To install SDR# now, simply download SDR# zip file from airspy.com/download. Unzip it to any folder on your PC. Next, to download the RTL-SDR drivers simply run the install-rtlsdr.bat file. We will soon be updating our Quickstart guide to incorporate these changes.

To install SDR# on Linux or OSX you can follow the guide over at rtlsdr.org/softwarelinux.

The official announcement is as follows:

Hi,

We have been relying on the .NET Framework 3.5 for quite some time until it’s no longer installed by default into the new operating systems. Microsoft also provides minimalist support of this version of the Framework on Windows 10 which handicaped the core and plugin developers in many ways. This also resulted in obscure bugs in the user base. So we moved recently the entire code base to the .NET 4.6 in order to refresh the software and make it compatible with modern operating systems like Windows 10.

This has many implications:

Better performance

Better programming API

Support of Windows 10

Support of Linux and Mac with Mono 4.0 and up

End of support of Windows XP and Vista

End of support of the ExtIO interface (not portable)

We coordinated this migration with all the plugins and front-ends developers so no body misses the boat.
The installation procedure has also changed and now the main package contains a batch file to download the dependencies required to run RTL-SDR.
This might be disturbing for a few, but the overall impact was judged positive and a better investment for the future, especially with the new API offered by .NET 4.6.

Cheers,

The SDR# Team

September 14, 2015

DesktopSDR MATLAB RTL-SDR Text Book Released

Back in August we posted about an RTL-SDR related text book called DesktopSDR that was due to be released later in the month. The text book discusses technical SDR topics, with the RTL-SDR used as the radio receiver and MATLAB used as the digital signal processing tool. It looks to be very useful to students of radio or communications engineering. There were a few delays with the release, but it is now out at www.desktopsdr.com. The eBook version is free whilst the print version is soon to be released on Amazon for about $68 USD for the paperback and $89 USD for the hard back.

To go along with the book they have also released several accompanying videos that are available at desktopsdr.com/videos.

The books blurb reads:

The availability of the RTL-SDR device for less than $20 brings software defined radio (SDR) to the home and work desktops of EE students, professional engineers and the maker community. The RTL-SDR can be used to acquire and sample RF (radio frequency) signals transmitted in the frequency range 25MHz to 1.75GHz, and the MATLAB and Simulink environment can be used to develop receivers using first principles DSP (digital signal processing) algorithms. Signals that the RTL-SDR hardware can receive include: FM radio, UHF band signals, ISM signals, GSM, 3G and LTE mobile radio, GPS and satellite signals, and any that the reader can (legally) transmit of course! In this book we introduce readers to SDR methods by viewing and analysing downconverted RF signals in the time and frequency domains, and then provide extensive DSP enabled SDR design exercises which the reader can learn from. The hands-on SDR design examples begin with simple AM and FM receivers, and move on to the more challenging aspects of PHY layer DSP, where receive filter chains, real-time channelisers, and advanced concepts such as carrier synchronisers, digital PLL designs and QPSK timing and phase synchronisers are implemented. In the book we will also show how the RTL-SDR can be used with SDR transmitters to develop complete communication systems, capable of transmitting payloads such as simple text strings, images and audio across the lab desktop.

September 14, 2015

Building an active wideband antenna for your SDR

As the RTL-SDR and other SDRs are wideband, we recommend that people use a wideband antenna if they want to scan over all the frequencies. Normally a discone or a scantenna is suggested as the wideband antenna of choice, however there are alternative designs such as the Dressler ARA-2000 which is a type of log spiral antenna that can receive from 50 – 2000 MHz. This particular product is no longer for sale, but an article detailing the breakdown of its construction can be found online.

The article shows how to build the antenna from scratch. The active element consists of a thin copper sheet (or copper foil) in the shape of a wedge which is rolled into a cylinder around a plastic sheet. It is then connected to a low noise amplifier (LNA), which is powered through a bias tee. For the LNA something like the LNA4ALL could be used if building it yourself.

This antenna may be something to consider if you are thinking about building your own wideband antenna. It has the advantage of being much smaller than a discone and it can also be fully enclosed in a plastic radome to that fully protects it from weather elements. The author of the article also writes that he saw better performance from this antenna than when compared with a discone.

September 7, 2015

ADS-B On Android App Now Supports 978 MHz FIS-B NEXRAD Weather and Traffic

The “ADS-B on Android” app has been updated and now supports the reception and display of 978 MHz UAT FIS-B Weather and Traffic data. The app also receives ADS-B data as per normal. To use the app you will need an RTL-SDR dongle and a USB OTG cable.

UAT stands for Universal Access Transceiver and is a protocol similar to ADS-B that is used mainly by smaller aircraft in the USA. UAT has some extra features for pilots compared to ADS-B. In addition to location information UAT provides a Traffic Information Service (TIS-B) which allows pilots in the air to see what ground control sees on their traditional RADAR system. It also provides a Flight Information Service-Broadcast (FIS-B) which includes NEXRAD weather data and other information. NEXRAD is an array of ground station weather radars that are used to provide pilots with accurate maps of precipitation and wind.

The free version of the app has ads and does not display NEXRAD weather radar on the default map. The pro version removes the ads and allows you to display a NEXRAD overlay on the map. It costs $2.50 USD.

Free Version: https://play.google.com/store/apps/details?id=com.wilsonae.android.usbserial

Pro Version: https://play.google.com/store/apps/details?id=com.wilsonae.android.usbserial.pro

NEXRAD FIS-B precipitation data displayed on map. — NEXRAD FIS-B precipitation data displayed on map on the pro version of “ADS-B On Android”

September 5, 2015

New product from FlightAware: A 1090 MHz Bandpass Filter for the RTL-SDR

FlightAware.com have released a new 1090 MHz bandpass filter that is intended for use with the RTL-SDR. FlightAware.com is a website that aggregates ADS-B aircraft location data from various contributors. The contributors are often users with RTL-SDR dongles running their PiAware software. By contributing to their service you gain access to their premium services for free.

The bandpass filter is available on Amazon for US customers for $19.95 USD and on eBay worldwide for $24.95 USD. This is the cheapest ADS-B filter we've seen yet. It comes in a metal case with SMA connectors, passes 980 MHz - 1150 MHz, has an insertion loss of about 1.65 dB at 1090 MHz and has about a 40dB drop outside the pass band. Over on their forums many users are reporting good results.

A bandpass filter blocks all frequencies apart from the range you are interested in, significantly reducing the effects of out of band interference. It is especially useful if you live near cell phone towers as these can easily interfere with the 1090 MHz frequency.

FlightAware also sell an ADS-B antenna on Amazon for $44.95 USD and worldwide on eBay for $54.99 which may be of interest to some people.

An alternative ADS-B filter for the RTL-SDR is the one made by Adam 9A4QV. Adams filter uses LTCC filter technology which gives lower insertion loss, but a less sharp cutoff.

September 4, 2015

Frequency Manager Suite Plugin for SDR#

Recently the popular Frequency Manager + Scanner plugin set for SDR# has been upgraded and renamed to the “Frequency Manager Suite”. The plugin can be downloaded from their new website at www.freqmgrsuite.com. The plugin suite includes a frequency scanner and manager, a scanner metrics recorder, a scheduler, an activity logger and a frequency entry plugin.

Apart from plugins the suite also now includes a plugin manager program called “Pluginator” which can help you to install and delete plugins without needing to edit the Plugins.xml file directly. There is also a new database manager tool which can help you to import frequency databases from online or other sources.

We have posted the full feature release below:

The Frequency Manager Suite (FMS) adds 4 more plugins to the previous set of 3:

Scheduler – allows you to schedule listening activities by date and time.

Activity Logger – records scanner activity to a file for later use.

Scanner Decisions – now a first-class plugin and also available as the classic stand-alone window. And you can change the position of the plugin without restarting SDR#.

Frequency Details – displays details about a frequency from your database. And you can change the position of the plugin without restarting SDR#.

New standalone applications also come with FMS:

Data Tools – this significantly upgraded import/export application lets you import data from 6 popular internet databases as well as generically-formatted files, and permits you to export your FMS databases to standard file format.

The Pluginator – an application that lets you add, delete, and change the order of plugins without ever having to hand-edit the SDR# file Plugins.xml. Just fill in the blanks.

New features in Frequency Manager + Scanner:

The new Preferences dialog allows customization without hand-editing a configuration file.

FMS configurations are now kept in a file separate from those of SDR#, permitting easier upgrades to SDR#.

You can have multiple frequency databases, and can change to a different database without restarting SDR#.

When tuning manually you can optionally change the radio settings (mode, BW, etc.) according to what’s in the database for the tuned frequency.

Scan resolution – high-res or low-res to favor speed over accuracy or vice versa.

Adjacent Frequency Rejection now displays its bandwidth on the spectrum analyzer.

Plus many other improvements and bug fixes.

fms_2

September 2, 2015

Detecting Pulsars (Rotating Neutron Stars) with an RTL-SDR

The RTL-SDR has been used for some time now as an amateur radio astronomy tool. Radio astronomers Peter W East and GM Gancio have recently uploaded a paper that details their experiments with detecting Pulsars with an RTL-SDR (doc file).

A pulsar is a rotating neutron star that emits a beam of electromagnetic radiation. If this beam points towards the earth, it can then be observed with a large dish antenna and a radio, like the RTL-SDR. The abstract of the paper reads:

This project sought to determine the minimum useful antenna aperture for amateur radio astronomers to successfully detect pulsars around the Hydrogen line frequency of 1420MHz. The technique relied on the collaboration with GM Gancio, who provided RTL SDR data of the Vela pulsar (B0833-45, J0835-4510) and others, collected with a 30m radio telescope. This data was processed to determine the achievable signal-to-noise ratio from which, the minimum useful dish size necessary for some effective amateur work, could be calculated. Two software packages were developed to do synchronous integration, a third to provide a power detection function and a fourth for spectrum analysis to recover pulsar rotation rate.

With their system the authors were able to detect and measure the rotation period of the Vela pulsar. Also, from their data they were able to estimate that the minimum dish aperture required to observe the Vela pulsar would be 6m, noting that the Vela pulsar is probably the strongest pulsar ever detected. They also write that by utilizing 5 RTL-SDRs to gather 10 MHz of bandwidth together with some processing that the minimum required dish aperture could be reduced to 3.5m.

The Vela pulsar pulse power integrated over a 50 second 100MB file, combining some 560 pulsar pulses.

In addition to these Pulsar experiments, Peter has also uploaded new papers about improving his Hydrogen Line RTL-SDR Telescope (pdf), and has updated his paper on improving the frequency stability of RTL-SDR’s with air cooling (doc file). Peter found that the frequency stability of the RTL-SDR (with standard oscillator) could be significantly improved by adding heat sinks and aircooling them. The graph from his paper below summarizes his results.

The air cooled and heatsinked RTL-SDRs — The air cooled and heat sinked RTL-SDRs

All of Peters papers can be found on his website at y1pwe.co.uk/RAProgs/index.html. He has many RTL-SDR radio astronomy related resources there, so check it out if you are interested.