RTL-SDR.com reader Marty Wittrock has written in to let us know that he has been successful in getting his HF modified “KN0CK” RTL-SDRs (and by extension standard RTL-SDRs) to work with Zadig and HDSDR on a PC running the Windows 10 technical preview on a VMWare image.
We decided to also test RTL-SDR compatibility with other common software on our own Windows 10 system. We tested SDR#, SDR-Radio, CubicSDR and Unitrunker and found them all to work fine with no problems either. Finally, we also tested the Airpsy and SDRPlay on Windows 10 and found no problems with those devices either.
After reading an article by the Washington Post about FBI surveillance aircraft spotted in the air after the West Balimore riots, John Wiseman decided to look for more information about these aircraft. Fortunately, John had on his hands a database of about 2 months of ADS-B data that was collected by his continuously running RTL-SDR + BeagleBone Black ADS-B decoder set up.
From reports on the internet John found out that FBI aircraft squawked with 4414 or 4415 codes, and used call signs like JENNA or JENA. With this information John decided to take a look through his ADS-B logs to see if if he could find anything similar. Out of 15,000 aircraft he had tracked, he found 9 aircraft in his logs that matched the criteria, and saw that they did exhibit suspicious behaviour such as circling over LA for hours at a time. Then by looking up their FAA records of the tail numbers of the suspicious aircraft, he was able to discover that these aircraft where licensed to companies with names like NG Research, OBR Leasing, Aerographics Inc. and PXW Services which are suspected Department of Justice front companies. John also writes:
If you Google the tail numbers of aircraft registered to those companies, you start to find forum and mailing list posts (often at sites that tilt toward paranoid/conspiracy/right wing, but not always) with people discussing these specific tail numbers and linking them to the FBI. Some of the supposed evidence includes details of radio communications that people have heard, e.g. talking about “being on station” or using callsigns that start with JENNA, JENA or ROSS, which are supposedly used by the FBI. Other posts claim that DOJ/FBI surveillance aircraft often squawk 4414 or 4415 on their transponders.
The planes use “persistent wide-area surveillance” to photograph large areas for hours at a time, Stanley said. The captured images allow authorities to go back in time, if necessary, to trace pedestrians and vehicles who come to their attention.
Other devices known as “dirtboxes,” “Stingrays” or “IMSI catchers” can capture cellphone data. Stanley said it’s still unclear what technologies have been used in the surveillance flights.
Possible FBI Surviellance Aircraft Path from flightradar24.com
Back in 2013 we posted about Juha Vierinen’s project in which he created a passive radar system from two RTL-SDR dongles, two Yagi antennas, and some custom processing code. Passive radar can be used to detect flying aircraft by listening for signals bouncing off their fuselage and can also be used to detect meteors entering the atmosphere. The radar is passive because it does not use a transmitter, but instead relies on other already strong transmitters such as FM broadcast radio stations. Juha writes:
A passive radar is a special type of radar [that] doesn’t require you to have a transmitter. You rely on a radio transmitter of opportunity provided by somebody else to illuminate radar targets. This can be your local radio or television station broadcasting with up to several megawatts of power.
How passive radar works
His previous write up was brief, but now over on Hackaday Juha has made a detailed post about his RTL-SDR passive radar project. In the post he explains what passive radar is, shows some examples of his and others results, shows how it can be done with an RTL-SDR dongle, and finally briefly explains the signal processing required. In his next post Juha aims to go into further detail on how passive radar works in practice.
Below we show a video that shows an example of one of his passive radar tests that was performed with a USRP software defined radio and two Yagi antennas.
This video shows a lot of airplanes around the New England area detected using a simple passive radar setup, consisting of: one USRP and two yagi antennas, a quad core linux PC. Every now and then an occasional specular meteor echo is observed too.
Over on YouTube balint256 (Balint), a researcher at Ettus (creators of the USRP line of software defined radios) has uploaded a video showing how he is using his USRP to help with frequency management at FPV time trial racing events. FPV a.k.a First Person View is a term used to describe the act of flying a remote controlled aircraft such as a quadcopter with an onboard camera that transmits live video down to the pilot. FPV racing is a new sport where pilots race FPV controlled drones around a track.
One important technical challenge at these events is frequency management. FPV drones use many frequencies at around 2.4 GHz for control and 5.8/2.4/1.3 GHz for video. With many drones in the air it is important that frequencies are managed appropriately so as to not jam each others signals.
To try and solve this problem Balint has been using GNU Radio coupled with a USRP X310 software defined radio to get very wide band RF spectrum waterfall views of the 2.4 and 5.8 GHz bands. In the waterfalls he is able to see when control signals and video signals are transmitted and at what frequency, and is able to tell if any are overlapping and jamming each other.
SDR Wideband Spectrum Monitoring for Drone FPV Frequency Management
In addition to this, Balint has also been working on his custom software defined radio based digital video downlink. Back in March we posted about his earlier work on this concept. In the video Balint demonstrates his drone with an on board USRP E310 which is used to send a custom 4.2 Mbps video downlink.
SDR digital video downlink (custom drone FPV) with E310 + webcam
Radio-Sky Spectrograph is a software application that is designed to produce waterfall displays similar to other software, but with a focus on observing radio astronomy phenomena.
Radio-Sky Spectrograph displays a waterfall spectrum. It is not so different from other programs that produce these displays except that it saves the spectra at a manageable data rate and provides channel widths that are consistent with many natural radio signal bandwidths. For terrestrial, solar flare, Jupiter decametric, or emission/absorption observations you might want to use RSS [Radio-Sky Spectrograph].
Over on YouTube user Adam Alicajic has uploaded a video showing how coax cable loss affects the frame rate when receiving ADS-B. To do this test Adam uses a precision attenuator in between his ADS-B antenna and RTL-SDR dongle to simulate attenuation from coax cable loss. His results show that for every 1 dB of attenuation the frame rate drops by about 10%.
Coax cable loss for common type of cable can be estimated with calculators available at http://www.net-comber.com/cable-loss.html and http://www.arrg.us/pages/Loss-Calc.htm. RG-6 cable has a low loss at 1090 MHz of about 0.23 – 0.32 dB per meter, whereas RG58 has a loss of about 0.5 – 0.6 dB per meter and RG174 (stock antenna cable on most RTL-SDR units) has a greater loss of about 1.2 dB per meter.
Coax length loss contribution to the bad ADS-B reception
The LightSail is a solar sailing spacecraft that has been launched by the planetary society. It is based on the “solar sail” concept, which uses a large reflective foil to harness the suns energy as a means of propulsion. The planetary society write about solar sails:
Solar sails use the sun’s energy as a method of propulsion—flight by light. Light is made of packets of energy called photons. While photons have no mass, a photon traveling as a packet of light has energy and momentum.
Solar sail spacecraft capture light momentum with large, lightweight mirrored surfaces—sails. As light reflects off a sail, most of its momentum is transferred, pushing on the sail. The resulting acceleration is small, but continuous. Unlike chemical rockets that provide short bursts of thrust, solar sails thrust continuously and can reach higher speeds over time.
The LightSail Concept
Currently a test mission of the LightSail concept is under way. The LightSail is in orbit and expected stay in orbit for about 1-2 months. Initially the mission had trouble with communications, but after an automatic reboot of the on board computers they have now confirmed that the LightSail is transmitting properly.
With an RTL-SDR and appropriate satellite antenna, it should be possible to monitor the LightSail. The LightSail transmits at a frequency of 437.435 MHz with the AX.25 protocol, FSK encoding at 9600bps and with a call sign of KK6HIT. The LightSail can be tracked at http://sail.planetary.org/missioncontrol and the planetary society are also requesting that amateur radio tracking enthusiasts email over any data they capture. Over on twitter some users have confirmed LightSail downlink hits:
Over on the swling.com blog, Thomas has uploaded a review of the TitanSDR Pro that was published in the May 2015 version of The Spectrum Monitor online magazine. Although the TitanSDR pro software defined radio is an expensive (1,380 EUR for the basic / 1,970 EUR for the PRO), it may be of interest to those looking to go further into the short wave listening hobby. The TitanSDR is a high performance 9 kHz to 32 MHz receiver with 16 built in preselectors and a bandwidth up to 2.1875 MHz. It’s main markets appear to be government intelligence and military, but it also finds good use in general short wave listening.
Thomas reviews the TitanSDR positively, liking its easy to use software and its superb sensitivity, but noting that it’s high price may be a bit off putting.
Also, in the current June version of The Spectrum Monitor magazine Thomas also reviews the SDRPlay, a $149 USD HF capable radio, also giving it a favourable review.
