This is just an announcement post to say that the RTL-SDR Blog V3 is now back in stock at Amazon USA and should be ready for shipping from there soon.
These include our bundle that comes with the new multipurpose dipole antenna kit for $25.95 USD. Please go to rtl-sdr.com/DIPOLE for further information about the new dipole kit.
Click here to visit our store for the links
The Outernet Dreamcatcher has recently gone on sale and is now only $39 USD. Previously it was priced at $79 and $59 USD. The Dreamcatcher is an RTL-SDR and computing board all built onto the same PCB. It has two SMA inputs - one is an L-band filtered and amplified input and the other is a standard wideband port good for all frequencies covered by a standard R820T2 RTL-SDR. For $39 it appears that you get the board itself, and a WiFi dongle, but no antennas, cables or SD cards are supplied with the unit.
In you are interested in the Dreamcatcher then back in June we posted a comprehensive review of it as well as their ceramic L-band patch antenna. Since then we've found that the Dreamcatcher has become much more stable and is very useful for applications like setting up a dedicated ADS-B receiver/feeder. At this price the Dreamcatcher is even better value than using a Raspberry Pi 3 plus external RTL-SDR dongle which can end up costing over $60 USD.
According to Outernet stocks appear to be fairly limited so this price probably won't last for too long.
Note: We'd advise not purchasing this for use with the Outernet data signal as we're unsure if that signal is going to last for much longer. Purchase it as a general purpose radio/computer instead.
A number of people have asked how to use SDR#'s SpyServer with an RTL-SDR. In this tutorial we will show how to set up SpyServer on both Windows and Linux systems. We try to assume as little knowledge as possible, but we do assume that you have decent experience with computers. Also for the Linux/Raspberry Pi setup we need to assume that you have some basic experience with Linux and setting up Raspberry Pi's.
SpyServer is a free RTL-SDR compatible SDR server that is designed to work with the popular SDR# software. It is actually designed for the Airspy range of products, but the author has also made it compatible with RTL-SDR dongles. Running a SpyServer allows you to connect to and use a remotely positioned RTL-SDR over a network connection (such as a local LAN/WiFi or the Internet). Once connected, using the dongle is the same as if the dongle was directly connected to the users PC.
Remote servers are useful as you may want to set up an antenna in a remote location (such as up on your roof or shack), and don't want to run a long lossy coax cable down to the PC. Instead you could run Ethernet cable, or avoid cables by using WiFi. All you'd need is power for a remote computing device like a Raspberry Pi 3. Perhaps you also have a great antenna location at a friends house, or other property and want to access that antenna remotely. Or maybe you want to use your radio while travelling.
SpyServer is similar to another tool that you may already be familiar with called rtl_tcp. However, SpyServer is regarded as superior because it is signficantly more efficient at network usage. Instead of sending the entire raw data like rtl_tcp does, SpyServer only sends the IQ data of the currently tuned in signal. Waterfall data is processed on the server and sent in compressed form. There is one disadvantage to SpyServer in that it requires slightly more powerful computing hardware like a Pi 2 or Pi 3, whereas rtl_tcp can run on the lowest end hardware.
Network usage when streaming with SpyServer will be about 120 KB/s when listening to WFM and about 38 KB/s when listening to narrow band modes for one client being connected. Multiple clients can connect to the SpyServer and share the same currently tuned bandwidth.
Over on GitHub Tom Wimmenhove has been experimenting with the car keyfob on his Subaru car, and has discovered that the rolling code scheme used is very weak and so can be easily exploited.
Most modern vehicles use some form of rolling code security on their wireless keyfobs to prevent unauthorized replay attacks. When the car owner presses a button on the keyfob, a unique rolling code is sent to the car. If it matches one of the codes currently stored in the car, the car will unlock and then invalidate that code so it can never be used again, thus preventing a replay attack. On the next press the keyfob sends a new code. In most designs when a code is used up, a new code is added to the list of valid codes via a random number generator based on a secure algorithm only known (presumably) to the engineers.
Essentially Tom found that instead of producing a randomly generated rolling code, the Subaru keyfob simply increments the rolling code number each time. This allows an attacker to perform a second key press simply recording an initial real key press, decoding the packet, increasing the decoded rolling code by one, then re-transmitting. It also means that the attacker could continually raise the rolling code value on the car himself, which would eventually make the real keyfob useless as the codes on the keyfob would be outdated and no longer match the same number range as the car.
The entire exploit was found on a super low budget. Tom used only an RTL-SDR and Raspberry Pi. The receive is obviously handled by the RTL-SDR, but the transmit side is handled by RPiTX which is software that allows the Raspberry Pi to transmit RF signals directly from a GPIO pin without the need for any additional transmitting hardware. Tom writes that the exploit probably affects the 2006 Subaru Baja, 2005 - 2010 Subaru Forester, 2004 - 2011 Subaru Impreza, 2005 - 2010 Subaru Legacy and the 2005 - 2010 Subaru Outback. Tom also writes that various dealers and spokes people have contacted him stating that the exploit probably only affects US models. If you have one of the affected models and are worried the only way to stay safe is to simply not use wireless entry on the keyfob, at least until/if Subaru fixes the issue with a recall. Although so far no statement from Subaru has been released.
Tom has also uploaded a demonstration video to YouTube which is shown below.
[Also seen on Hackaday, Bleeping Computer and The Register]
As part of their senior project Matthew May & Brendan Harlow of Champlain College worked on a project that involved creating their own software defined radio based portable cell phone network. If you're interested their setup is nicely documented on their project page. Basically it consists of a bladeRF software defined radio and Raspberry Pi running the YateBTS base station software. This is nothing new in terms of work done before, but the clear documentation makes it a good starting point for anyone looking at building their own SDR based cell basestation.
A custom cell basestation may be useful for those in remote areas without commercial cell phone reception, during disasters or even just to create a type of secondary network in your home.
[Also seen on Hackaday and Motherboard]
Over on Twitter Denis (@uhfsatcom) has recently been teasing us with photos of his 16 dongle RTL-SDR V3 setup. The system looks like it's designed to be a satcom band WebSDR receiver.
The satcom band is around 240 - 270 MHz and mostly consists of various military satellites that act as simple repeaters which are often hijacked by pirates. WebSDR is a piece of software that allows for online web streaming of SDR radios. Users from all over the world can listen in if made public. Denis has also uploaded a short video showing a test of 8 dongles running and receiving the satcom band on his WebSDR system.
We look forward to hearing more updates on this project!
first launch of the 16x rtl sdr v.3 websdr pic.twitter.com/gYKsqNt5Ap
— Denis (@uhfsatcom) October 14, 2017
native rtl dongle vs rtl-sdr v3. No preamp, little satcom antenna. So... native lossed ~ 3db SNR. pic.twitter.com/rOoQ7yBO86
— Denis (@uhfsatcom) September 23, 2017
Over the last month SDRSharp's SpyServer has been updated several times. SpyServer is a streaming server for SDR# which allows you to use Airspy and RTL-SDR radios remotely over a network connection.
The updates brought improvements such as IQ PCM compression at various bit depths including an efficient 8-bit mode, removing the DC spike residual in the 8-bit streaming mode, and recently improving the 8-bit mode to work like lossy compression for strong signals.
We tested the new 8-bit PCM streaming mode and found it to be extremely efficient with network usage. When streaming at 2 MHz with an RTL-SDR a WFM signal on the older SpyServer versions used to use about 1.2 MB/s without any compression modes, and now with 8-bit compression active it only uses 322 KB/s. A NFM signal used to require 120 KB/s, now only requiring about 38 KB/s. No DC spike is present and no degradation in reception quality is noticeable unless the signal requires over 70 dB of dynamic range, which is unlikely for most signals.
If you've had trouble with SpyServer or rtl_tcp not working well on your slow network connection, then the new updated SpyServer may be the solution for you.
Prog, the author of SDR# and SpySever writes about the update on the Airspy group:
This new development allows you to stream large signals over 8bit and reduce the network bandwidth.
The server will try to pack the useful signals into whatever bit depth you select ensuring optimal SNR for the transport. No manual scaling required.
Alexander Csete (OZ9AEC) is the programmer behind the popular GQRX software. Recently Alexander has received a review sample of the upcoming Airspy HF+ and has been uploading videos showing it in action to his YouTube channel.
The Airspy HF+ is a soon to be released low cost (expected price $149 USD) yet high performance HF/VHF receiver designed for DXing with exceptional performance in the presence of strong overloading signals. If you are interested we also have our own review of the HF+ available here.
In the video below Alexander demonstrates the HF+ on SSB and CW modes in his GQRX software. See his YouTube channel for the rest of the videos. Currently there are about 7 videos demonstrating the HF+ on his channel.
Over on his Twitter account @csete Alex has also been uploading several images of the HF+ in action as well as some screenshots of it being compared against the RFSpace Cloud-IQ which is a $629 USD SDR. So far his impressions of the HF+ seem very high.
Looks like the radar guys have learned to stay outside the amateur radio bands. Now we can study selective fading ? pic.twitter.com/8y8rDoXJh0
— Alexandru Csete (@csete) October 22, 2017
Side by side comparison of Cloud-IQ and Airspy HF+ on MW
— Alexandru Csete (@csete) October 18, 2017
Cloud-IQ: 370120 sps (RBW 22.6 Hz)
Airspy HF+: 768000 sps ↓2 (RBW 23.4 Hz) pic.twitter.com/uUUard2XmZ
Wow, I have never seen the timing signals around 1.8 MHz so strong with this antenna, which only goes down to 3.6 MHz. pic.twitter.com/qoj8fryXBZ
— Alexandru Csete (@csete) October 15, 2017
