Tagged: rtl2832u

Installing OpenWRT and RTL-SDR on a Used $20 Router

Over on his YouTube channel GusGorman402 has uploaded a video tutorial showing how to take an old internet router and install OpenWRT and the RTL-SDR drivers on it. OpenWRT is a third party Linux based router firmware which can greatly expand the usefulness of a standard router. As it is Linux based it is possible to install the RTL-SDR Linux drivers on the router and use the router as a cheap RTL-SDR streaming or decoding platform.

Gus’s tutorial takes us from the beginning where he first shows how to install OpenWRT firmware over the stock firmware on the router and how to configure the settings. He then shows how to install the RTL-SDR drivers and run software like rtl_tcp and dump1090 with opkg and luci. 

Installing OpenWrt and RTL-SDR libs on used router

New Nano 3 RTL-SDR Available from NooElec

NooElec have just released their new NESDR Nano 3 RTL-SDR dongle for $27.95 USD. This is a new iteration in their line of ‘nano’ sized dongles, which are very small and suitable for use on small devices like Raspberry Pi’s and mobile phones. These nano form factor RTL-SDR dongles are also commonly used with the Stratux project which aims to bring lost cost ADS-B and UAT capabilities to small airplane pilots.

The Nano 3 appears to have a standard nano sized RTL-SDR PCB with TCXO inside, but comes with a new fully enclosed metal case with internal thermal coupling pads for cooling. A small external heatsink is also provided for optional use with the dongle. The dongle also uses a standard MCX connector, but the kit comes with an MCX to SMA F adapter. We’re not sure if the cooling from the small metal case will be enough to solve the L-band PLL lock problem, but perhaps when combined with the modified L-band driver tweak it might be enough. Failing that the external heatsink combined with slight airflow from a fan should be enough.

The NESDR Nano 3 small form factor RTL-SDR
The NESDR Nano 3 small form factor RTL-SDR

The previous model called the Nano 2, was also redesigned from the generic nano models for better cooling and to be able to use a TCXO. However, some tests by Chris of the Stratux project seem to show that the Nano 2 is quite a bit noisier than the cheaper generic nano dongles, and actually runs about 40 degrees F hotter. Noise is a problem with these small dongles as the noisy digital and switch mode sections are much closer to the RF sensitive parts. Heat is also an issue due to the lack of PCB space for heat dissipation. Hopefully the Nano 3 resolves these issues with the metal case and improved cooling.

There are now several generations and models of these ‘nano’ RTL-SDRs available. All briefly described below:

  1. Generic Nano Dongles:
    1. $16.99 USD + shipping costs.
    2. First nano dongles designed originally for DVB-T TV use. Difficult to find now, no longer seems to be sold apart from one US seller on eBay.
    3. Still a good choice, but the lack of TCXO limits the usefulness for many applications.
  2. NooElec Nano 2:
    1.  $21.95 USD without TCXO, $23.95 with TCXO.
    2. Slight redesign of the generic dongles for better cooling and TCXO. Although cooling and noise benefits are debated.
    3. Good choice if you like the Nano form factor and want a dongle with accurate TCXO clock.
  3. Stratux Dongle (with ADS-B/UAT Antennas):
    1. Two dongles for $40 USD with antennas, or two for $35 USD without antennas. We also wholesaled a few from them and sell them on our store for intl. buyers @ 16.95 USD each incl. shipping.
    2. Redesigned for low power usage and less noise. Uses a switch mode power supply for less power wastage, but designed to be unaffected by any additional switch mode noise. Runs about 60 degrees F cooler than the Nano 2 and 16F cooler than the generic. Does not have an enclosure so is a bit more fragile. Also does not have a TCXO.
    3. Good choice for Stratux or similar projects might struggle with the power requirements of multiple dongles on a Pi3. Doesn’t have a TCXO so mainly useful for frequency insensitive applications like ADS-B.
  4. NooElec Nano 3:
    1. $27.95 USD
    2. Redesigned enclosure with thermal pad coupling and heatsinks. Comes with TCXO.
    3. Untested by us, but we think it’s probably better than the Nano 2. So a good choice if you like the Nano form factor and want a TCXO dongle.

Installing and Using SDRTrunk on Linux for Live Trunk Tracking with an RTL-SDR

SDRTrunk is a cross platform Java based piece of software that can be used for following trunked radio conversations. In addition to trunk tracking it also has a built in P25 Phase 1 decoder. Compared to Unitrunker SDRTrunk is an all-in-one package, and currently it supports most trunking system control channels, but unlike Unitrunker it still misses out on some systems EDACS and DMR.

Over on his YouTube channel AVT Marketing has uploaded an excellent 6-part video series that shows how to install SDRTrunk and the Java runtime environment on Ubuntu Linux. The sections covered include, installing Java, setting the Java environment variables, installing other SDRTrunk prerequisites such as Apache Ant and the JMBE audio codec for decoding P25, and finally actually using and setting up SDRTrunk. Like all of AVT’s other videos, this is an excellent tutorial that takes you through the entire process from the very beginning so is useful for beginners as well.

Installing SDRTrunk & Java JRE on Ubuntu Linux

If you’re new to trunking: Trunking systems are typically used with handheld radio systems (e.g. those that police, security guards, workmen etc carry around). The basic idea is that each radio constantly listens to a digital control channel which tells it what frequency to switch to if a call is being made. This allows the frequency spectrum to be shared, instead of designating one fixed frequency per user which would be very inefficient. But this system makes it difficult for scanner radios to listen in to, because the voice frequency could change at any time. Therefore software like Unitrunker and SDRTrunk which can decode the control channel is required. In addition many new systems use digital audio like P25 or DMR which requires digital decoders like SDRTrunk or DSDPlus.

Creating an Encrypted ADS-B Plane Spotter with a Raspberry Pi, RTL-SDR and SSL

These days it’s quite easy to share your ADS-B reception on the internet with giant worldwide aggregation sites like flightaware.com and flightradar24.com. These sites aggregate received ADS-B plane location data received by RTL-SDR users from all around the world and display it all together on a web based map.

However, what if you don’t want to share your data on these sites but still want to share it over the internet with friends or others without directly revealing your IP address? Some of the team at beame.io have uploaded a post that shows how to use their beame.io service to securely share your ADS-B reception over the internet. Beame.io appears to be a service that can be used to expose local network applications to the internet via secure HTTPS tunneling. Essentially this can allow someone to connect to a service on your PC (e.g. ADS-B mapping), without you revealing your public IP address and therefore exposing your PC to hacking.

On their post they show how to set up the RTL-SDR compatible dump1090 ADS-B decoder on a Raspberry Pi, and then connect it to their beame-instal-ssl service.

Encrypted ADS-B Sharing with the beame.io service.
Encrypted ADS-B Sharing with the beame.io service.

Detecting Car Keyfob Jamming With a Raspberry Pi and RTL-SDR

It’s been known for a while now that it is possible to break into cars using simple wireless attacks that involve jamming of the car keyfob frequency. Sammy Kamkars “rolljam” is one such example that can be built with a cheap Arduino and RF transceiver chip. One way to secure yourself against wireless attacks like this is to run a jammer detector.

A jammer detector is quite simple in theory – just continuously measure the signal strength at the car keyfob frequency and notify the user if a strong continuous signal is detected. Over on his blog author mikeh69 has posted about his work in creating a wireless jammer detector out of a Raspberry Pi and RTL-SDR dongle. He uses a Python script and some C code that he developed to create a tool that displays the signal strength on an onscreen bar graph and also conveys signal strength information via audio tones. He writes that with a pair of earphones and battery pack you can use the system while walking around searching for the source of a jammer.

Mikeh69’s post goes into further detail about installing the software and required dependencies. He also writes that in the future he wants to experiment with creating large area surveys by logging signal strength data against GPS locations to generate a heatmap. If you are interested in that idea, then it is similar to Tim Haven’s driveby noise detector system which also used RTL-SDR dongles, or the heatmap feature in RTLSDR Scanner.

[Also seen on Hackaday]

RTL-SDR + Raspberry Pi Jammer Detector.
RTL-SDR + Raspberry Pi Jammer Detector.

Receiving ADS-B Jetliner Traffic with a Simple Paper Clip

Over on YouTube user icholakov has uploaded a new video showing how easy it can be to build a cheap ADS-B antenna out of a simple paper clip and coax connector. Modern aircraft carry an ADS-B transceiver and antenna which broadcasts the current GPS location of the aircraft. This is used for collision avoidance and air traffic control, but anyone with a receiver like an RTL-SDR can also receive and decode these signals, and plot locally received air traffic on Google maps. We have a tutorial for decoding ADS-B signals available here.

In the video Thomas Cholakov (N1SPY) explains the concept behind the antenna design, which is a standard 1/4 wave ground plane cut to the correct dimensions for ADS-B at 1090 MHz. He cuts 5 pieces of the same length, with one piece used as the active whip element, and four pieces used in the ground plane element. The paper clip pieces are then soldered onto a coaxial connector and then the antenna is ready to be used.

2017: Paper Clip vs. Jetliner Traffic

QIRX SDR Updated: Legacy DAB, DAB Transmitter Identifications and more

Back in May of this year we posted about QIRX SDR, which back then was a brand new multimode SDR program compatible with the RTL-SDR. One of its defining features is that it has a built in DAB+ decoder. Recently QIRX SDR has been updated to version 0.9.1, the new features are quoted below:

General:

  • Updated Documentation
  • Device Frontend: Manual Center Freq. Correction in kHz
  • Waterfall Spectrum
  • Raw Recording: Playback Control, for a timed positioning (“seek”) in “arbitrary” large (GBytes) recorded raw files.

DAB:

  • Legacy DAB, intended for users where DAB+ is not generally available, like in the UK or Spain. As this could only be superficially tested here in Germany (no standard DAB any more, I used some raw samples recorded in Madrid), I would be very interested in feedback of users about it.
  • Synchronization of raw files recorded with central frequency offset
  • Enhanced manual synchronization control, mainly for tests in mobile environments
  • Detection of the Transmitter Identifications (TII). However, as this is a feature only useful for specialized applications, it is not included in the distribution. To my knowledge, qirx is the only DAB SDR having this feature.

Some Bug fixing.

The QIRX team have also added a new Quickstart Guide to help users get set up with their software quickly. In addition QIRX author Clem also writes that the QIRX software will be demonstrated during this weekends Ham-Radio fair in Friedrichshafen, Germany.

QIRX SDR Updated
QIRX SDR Updated

OpenWebRX Updates: 3D Waterfall and BPSK31 Demodulator

OpenWebRX has recently been updated and now includes a 3D waterfall display and a BPSK31 demodulator. OpenWebRX is a popular program which allows you to stream an SDR like the RTL-SDR over the internet efficiently. A number of clients can connect to your server and tune anywhere within a predefined bandwidth. Many examples of OpenWebRX running on RTL-SDRs and KiwiSDRs can be found on sdr.hu.

The 3D waterfall is quite an interesting feature as it allows you to visual signal strength, frequency and time all at once. BPSK31 is a popular amateur radio digital mode for making QSO’s (contacts). The new decoder allows you to zoom in closely on the band with high resolution and select with the mouse which BPSK31 channel you’d like to decode.

András Retzler, creator of OpenWebRX also writes that he’s now completed his Masters Thesis (congratutions!) on the topic of “Integrating digital demodulators into OpenWebRX”. His thesis is available for download here and looks to be an interesting read.

OpenWebRX BPSK31 Mode
OpenWebRX BPSK31 Mode