Gat3way has recently posted on his blog an article showing how he was able to receive a signal from the Lunar Reconnaissance Orbiter (LRO) using only an RTL-SDR, WiFi grid antenna and a low noise block (LNB). The LRO is a NASA spacecraft which is currently orbiting and being used to create maps of the moon.
The LRO transmits a tracking, telemetry and control (TT&C) signal at 2271.125 MHz which is in the S band (2 to 4 GHz). Since the S band frequencies are commonly used for Indovision satellite TV, gat3way was able to find a cheap LNB which could downconvert the GHz level S band frequencies down into a frequency receivable by the RTL-SDR. For the antenna he used a high 22dBi gain motor controlled WiFi mesh parabolic grid antenna.
After aiming the antenna at the moon, gat3way was able to clearly see the LRO carrier signal in the RTL-SDR waterfall as shown in the image below.
Amateur radio hobbyist DE8MSH recently wrote in to let us know about a project he has been working on. His project involves using a Raspberry Pi B and RTL-SDR to automatically log a wide band heatmap using rtl_power. Rtl_power is a command line tool that will log signal strengths to a csv file using the RTL-SDR over a very large definable bandwidth.
To do the automatic logging the Raspberry Pi runs rtl_power for 23 hours constantly writing data to a mounted hard drive. After 23 hours the heatmap image is calculated and then uploaded to a webpage at http://qth.at/de8msh/listheatmaps.php. The scheduling is performed by a cron job.
DE8MSH has also been working on a second related project over at http://www.qth.at/de8msh/hm/pic.html. The heatmap on this page shows various transmissions from weather balloons. As you mouse over those transmissions, the QTH (location) of those weather balloon transmissions is shown as well as the frequency and time of where the mouse pointer currently is.
To do this he used a CDCLVC1310-EVM board which provides up to 10 clock outputs and then connected four of the clock outputs to the clock inputs of four separate RTL-SDR dongles. He then uses a GNU Radio program to correlate the signals from each RTL-SDR stick.
Recently we have seen two applications of an RTL-SDR based coherent multichannel receiver used in passive a radar systems here and here.
On the RTL2832U dongle side, he modified the RTL2832U Linux DVB-T drivers (not the SDR drivers) to work on the 1.3 GHz band. The intention of this camera is for it to fly on a rocket mission. In the YouTube video below he has uploaded some sample footage with the RTL2832U dongle receiving the stream from 300 meters away.
Over on YouTube user Jiao Xianjun has uploaded a video showing how he was able to transmit an ADS-B signal from his HackRF One and receive it using an RTL-SDR with dump1090. He transmits a low power signal which shows a fake plane flying over the Senkaku islands.
Important Note: While this warning is also on the video we feel that we should re-emphasize that you should never transmit anything at 1090 MHz unless you are authorized to do so and are in a controlled RF environment.
ADS-B out by HACKRF and received by rtl-sdr + dump1090
Recently we posted how RTLSDR Scanner has been updated to allow interfacing with a GPS device. This allows you to make signal strength maps by driving around and recording both signal strength and GPS location together.
You can hover over each of the controls to see a tool tip explaining which each button does.
Recently a similar rtl_power GUI was released and shown in this post. There is also the more featured python based RTLSDR Scanner that is not based on rtl_power which does a similar job. However, the rtl_power based GUIs appear to be much faster at scanning.
Over on YouTube user Ben Silverwood has uploaded a video showing the results of his RTL-SDR passive radar. The passive radar works using two RTL-SDR dongles receiving a DAB radio tower’s radio waves that are reflected off the aircraft. On the video you are able to see the aircraft radar blip on the animated Matlab plots.
Back in March we showed a beta version of Tyler Watts ScanEyes trunked call log recorder software. Now Tyler has released a more complete version of his ScanEyes software. A live version of the software can be found at sdrscan.com. ScanEyes works by using a software defined radio such as the RTL-SDR combined with trunking following software Unitrunker and optional P25 decoder DSD/DSD+ to archive all calls made on a trunked radio system. A user can then later go into the web interface and view and listen to archived calls.