September 14, 2013

Review of the SDR UP-100 Upconverter

Akos from the SDR for mariners blog has written a review on the SDR UP-100 upconverter. The SDR UP-100 is a 50 USD upconverter for the RTL-SDR and similar software defined radios which is made by the same person behind the LNA4ALL low noise amplifier. Upconverters allow the RTL-SDR to receive between 0 and 30 MHz, where ham radio, military, marine and many other interesting signals exist.

In the review Akos tests the SDR UP-100 with a 6 meter random wire antenna and an RTL-SDR. His results show that the upconverter works well as expected. In the future he hopes to compare the SDR UP-100 with the Ham-It-Up Upconverter from Nooelec.

SDR UP-100

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September 12, 2013

2-Channel AIS Receiver with RTL-SDR and GNUAIS

Blogger OZ9AEC has written a post on his blog showing how he made a 2-channel AIS receiver using the RTL-SDR, GNU Radio and GNUAis. AIS is a radio protocol used by boats to broadcast their position and speed which is then used to create a type of radar system to help avoid collisions. AIS signals are transmitted periodically on one of two channels. Two channels are used to improve capacity and help avoid interference if two signals from different boats are broadcast at the same time.

Before this, most AIS receiver implementations we’d seen that used the RTL-SDR received only on a single channel. OZ9AEC’s GNU Radio program receives on both channels simultaneously like a commercial AIS receiver does and is thus a better receiver. He eventually plans to get this receiver to run on a Beaglebone.

See his post for instructions and to download the GRC files.

Update: Another AIS decoder known as gr-ais is also capable of 2 channel AIS, and bristromat from Reddit has written a tutorial on setting it up and running it with OpenCPN.

Two channel AIS Block Diagram

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September 11, 2013

RTL-SDR on the Nokia N900

Over on the maemo.org forums, user xes has written a post explaining how to get the RTL-SDR working on the Nokia N900 mobile phone. The Nokia N900 runs a modified version of Linux known as maemo, and so is able to use the RTL-SDR drivers with some modifications. Attached to the post by xes are the N900 compatible RTL-SDR drivers, GNU Radio 3.6.2, GQRX and also MultimonNG.

Nokia N900 running RTL-SDR

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September 10, 2013

Exploring the Wireless World with the USRP B200

Ettus Research, creators of the high end USRP software defined radios have posted a well produced video on YouTube showing off various applications that an SDR can perform. In the video they go through and explain FM Radio, APRS, AIS, Multi-Channel Decoding, Pagers, ADS-B/Mode S, ACARS, RADAR Analysis and 802.11a decoding.

For these apps they use a USRP B200, which costs $675 USD. Most of the applications shown should also be compatible with other SDRs, such as the cheaper HackRF and BladeRFs. Even the cheap RTL-SDR will at least work for FM Radio, APRS, AIS, Pagers, ADS-B and ACARS. Of course, the USRP is still probably the most top of the line SDR available.

USRP B200: Exploring the Wireless World

Watch this video on YouTube

Update: The video creator, Balint has also uploaded a video on his personal YouTube channel which is a longer presentation of the topics that were briefly discussed in the USRP video.

Hacking the Wireless World (short version) @ iSec Open Forum

Watch this video on YouTube

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September 9, 2013

In Car ADS-B with a Raspberry Pi and RTL-SDR

Over on YouTube user adsbrus shows us his project which is an in car ADS-B aircraft tracker using a Raspberry Pi mini computer and an RTL-SDR. The system uses an LCD screen mounted where the car radio usually is to show aircraft identifier, altitude, and speed information in text.

ADS-B in CAR (Raspberry PI & USB TV RTL2832U+R820T)

Watch this video on YouTube

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September 7, 2013

Exploring Unintended Radio Emissions with the RTL-SDR – Talk now available on YouTube

A few weeks back we posted about some slides from the Defcon conference by information security researcher Melissa Elliot which detailed how she used an RTL-SDR to explore the world of unintended radio emissions.

The talk to go with the slides is now available on YouTube

DEF CON 21 - Melissa Elliott - Noise Floor Exploring Unintentional Radio Emissions

Watch this video on YouTube

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September 5, 2013

Tip to Reduce Radio Interference on the RTL-SDR

A few months back we posted about a tip to reduce RFI (Radio Frequency Interference) on the RTL-SDR. Now Akos from the SDR for mariners blog has tried this tip for himself and written about his experience with it, after getting inspired to by a post in the rtl-sdr.com/forum.

To reduce RFI, the tip recommends disconnecting the shield connection of the USB cable from the ground connection of the RTL-SDR dongle. This overcomes a design flaw in the RTL-SDR which allows the shield of the USB extension cable to act as an antenna, causing unwanted RFI.

What Akos did was to remove the metal part of the USB extension cables connector to prevent any ground connection. This already reduced an interfering signal by 10dB. He also found that wrapping the connection point in foil further reduced the noise. Connecting coax to the ground then coiling it up and putting the RTL-SDR in the center of the coil also appears to significantly reduce RFI.

Update: Akos has also tried using ferrite chokes on the USB cable, and also found they significantly reduce interference.

Check out the full post by Akos for more information here

RFI noise reduction in the RTL-SDR

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September 3, 2013

Improved SDR Support for Kali Linux

The blog at needsec.com brings us news that Kali Linux is soon to be updated to version 1.0.5 which will come with several software defined radio tools preinstalled. Kali is a Debian Linux based operating system that is popular with the security and penetration testing community as it comes with several relevant tools preinstalled. This new version adds several useful SDR software programs including