December 18, 2013

Cooling the RTL-SDR

Over at the SDR for Mariners blog, Akos has put together a write up on his methods for cooling the RTL-SDR dongle. Cooling can help reduce temperature related frequency drift, which occurs as the dongles crystal oscillator heats up over time.

One of his recommendations is to try oil cooling the dongle. This involves completely immersing the dongle in sunflower or vegetable oil. Since oil is not electrically conductive, it will not short the circuits, and the oil will help to dissipate the heat buildup generated by the dongle. Some of his other recommendations involve drilling extra holes in the dongle casing, and adding fan cooling.

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December 17, 2013

Locating an Interfering Signal with Radio Direction Finding and the RTL-SDR

The people at the MIT Haystack Observatory discovered recently that someone was transmitting an interfering signal on their licensed radar band. The interferer was effectively jamming the radar, preventing them from carrying out any experiments.

After checking for local causes of interference and finding nothing, they decided that the interferer must be coming from further away. To find the location of the jamming signal they did some radio direction finding. This involved driving around with Yagi and magnetic loop antennas and RTL-SDR and USRP N200 SDRs and then measuring the signal strength at various points.

For the software they used a custom GNURadio block which calculated the power spectra using the FFTW C library, and averaged the results to disk. They then post processed the data to calculated the RFI power, and correlated the data with GPS coordinates recorded on his phone.

After all the data was processed, they discovered that the interference originated from an FM radio tower which had a faulty FSK telemetry link. They notified the engineer responsible who then replaced the link and the interference disappeared.

RFI strength at various geographic locations

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December 17, 2013

Simplified RTL1090 Installer

The popular RTL-SDR ADS-B decoder RTL1090 requires the rtlsdr.dll and libusb.dll files to be manually downloaded and then placed into the RTL1090 folder. However, now the author of RTL1090 has created an automatic installer which will download and install all the required files automatically.

This internet based utility helps you with setting up a complete RTL1090 installation with almost no manual intervention. It automatically downloads the relevant files as rtlsdr.dll, zadig.exe and helps to configure zadig with a built in tutorial.

The installer is called the IMU (Installer and Maintenance Utility) and can be download from the RTL1090 website at rtl1090.web99.de.

News via sonicgoose.com.

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December 17, 2013

ADS-B Virtual Radar RTL-SDR Tutorial in the ARRL QST Magazine

The American Radio Relay League (ARRL) a.k.a The American National Association for Amateur Radio has put online a freely available ADS-B tutorial featured in their monthly QST magazine, written by Robert Nichols, W9RAN. The tutorial focuses on using an R820T RTL-SDR dongle to receive ADS-B signals, and then using computer software to decode the signals and create a virtual aircraft radar.

ADS-B is a protocol used by most modern aircraft to broadcast their position and altitude which is determined via GPS. ADS-B is intended to supplement and eventually replace traditional radar.

In this ADS-B tutorial, they show how to create a weatherproofed 1090 MHz collinear antenna from RG-6/U coax and PVC pipe and how to use the ADSB# and virtual radar server software to decode and visualize aircraft positions, like a radar.

If interested, we also have an ADS-B virtual radar tutorial that can be found here.

ADS-B Virtual Air Radar Tutorial by the ARRL

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December 16, 2013

Receiving the Chinese Yutu Moon Rover with the RTL-SDR

Amateur radio hobbyist EB3FRN was able to use his RTL-SDR to receive the telemetry signal from the recently landed Chinese Yutu moon rover. The Yutu rover transmits at 8462.08000 MHz, which is outside of any RTL-SDRs frequency range, so he used a downconverter with a local oscillator at 8 GHz to convert the signal to 462 MHz.

For the software he used Baudline and rtl_fm as the receiver. He has posted a short audio clip of the received signal on his blog as well.

Chinese Yutu Moon Rover Received with RTL-SDR and Baudline

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December 16, 2013

Review of Various Lesser Known RTL-SDR Dongles

While the standard R820T dongles are the cheapest, most popular and best overall performing, there are other lesser known dongles variants out there which contain RTL2832 chips. Gough Lui has reviewed two lesser known dongles with Belling Lee (PAL) connectors on his blog.

One dongle uses the FC0013 tuner, and the other uses the R820T chip. Gough opens the dongles up and inspects their electronics and gives his opinions on the design.

One of the alternative R280T models with PAL antenna connectors — One of the alternative R280T models with a PAL antenna connector

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December 12, 2013

Modified RTL-SDR with Temperature Controlled Oscillator (TCXO)

Nobu Saito, a Japanese RTL-SDR hardware developer has come out with a modified RTL-SDR which has a +-2PPM 28.8MHz Temperature Controller Oscillator (TCXO) instead of the standard 28.8 MHz stock oscillator. (Note this link is machine translated to English from Japanese).

Normally 28.8 MHz TCXO’s are difficult to find, but Nobu was able to find a source in Japan, and he is now selling on his Amazon Store (with international shipping) modified dongles.

The oscillator on the RTL-SDR is prone to thermal drift, which means that as the dongle heats up from use, the frequency you are tuned to may change over time. A TCXO compensates for differences in temperature, and thus keeps the frequency stable as the temperature changes. This is extremely useful for applications such as receiving GPS, Beacons, APT, HFDL, and for radio astronomy.

Nobu sells the modified dongle with TCXO on this page. We expect to receive a sample of his product soon and will write a review when we receive it.

Edit: Now available at the 1090 MHz webstore.

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December 12, 2013

Linux LiveDVD that Supports RTL-SDR and HackRF

Andy (KB1OIQ) has put together an Ubuntu Linux LiveDVD which has preinstalled RTL-SDR support, as well as a large number of amateur radio programs. The LiveDVD also supports both 32 and 64 bit machines.

A LiveDVD allows you to boot Linux directly from a DVD, rather than needing to install Linux onto your hard drive.

You can download the iso files directly from these links below

http://hivelocity.dl.sourceforge.net/project/kb1oiq-andysham/ubuntu-remix-14-32bit.iso

http://hivelocity.dl.sourceforge.net/project/kb1oiq-andysham/ubuntu-remix-14-64bit.iso

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