In this episode of Frugal Radio's ongoing SDR Guide videos Rob demonstrates how he uses Unitrunker and SDR Trunk with SDRs like an RTL-SDR to monitor Public Safety networks in his area. Rob writes:
This is a video demonstrating how I use UniTrunker and SDRTrunk with Software Defined Radios to monitor multiple Public Safety networks in my area.
There is some information on how trunked systems work, and you can hear how my SDRs produce better P25 audio on a Simulcast (LSM) system than some scanners.
I use a couple of RTL-SDR v3s and an Airspy R2 in this episode.
2020 SDR Guide Ep 6 : Trunk tracking Public Safety systems with UniTrunker and SDRTrunk
At this years ICNP 2020 IEEE conference a paper titled "Real-World ADS-B signal recognition based on Radio Frequency Fingerprinting" (pdf file) was presented by researchers from Harbin Engineering University in China. The idea presented in the paper is to use RF "fingerprinting" techniques to uniquely identify and confirm that the ADS-B signal originates from the correct aircraft source.
RF fingerprinting works on the premise that every transmitter has small manufacturing variances that result in slightly different signals be transmitted, resulting in a unique "fingerprint" that can be traced to a particular transmitter. The idea here is to use these fingerprints to ensure that a known aircraft is indeed transmitting an ADS-B signal and the signal is not being transmitted from a fake spoofer. ADS-B is completely unencrypted and not authenticated, so spoofing of ADS-B signals may be a real security threat.
In the teams research they use an RTL-SDR to collect ADS-B signals from five different aircraft. They then use that data to create "Contour Stellar Images" and train a deep learning neural network which after training accurately identifies which aircraft a signal comes from.
Thank you to a few users who have submitted links to u/ThePhotoChemist's Reddit post showing his e-ink display for his live GOES-16 weather satellite images. The post doesn't go into much detail about the setup, however it seems that he is using a Raspberry Pi, and displaying the images via a 9.7 inch E-Ink display which he notes does not come cheaply. He also notes that the resolution is quite low, and that it's limited to 16 shades of grey, however the images do still look good on it. The display is mounted into a picture frame which makes a very nice display piece.
If you're interested in receiving live GOES (or GK-2A) weather satellite images with an RTL-SDR we have a tutorial available here.
Thank you to Happysat for reviewing the QO-100 Bullseye LNB which we have available in our store, eBay and Aliexpress. The Bullseye LNB is an ultra stable TCXO (temperature compensated oscillator) based LNB which makes it very good at receiving the narrowband signals on the QO-100 amateur geostationary satellite.
Standard LNBs that are sometimes used for QO-100 are not designed for narrowband signals and hence do not have temperature compensated oscillator which can result in the signals drifting in frequency significantly as the ambient temperature fluctuates. Happysat also notes that the extra stability seems to have increased signal strength on the more wideband DATV reception as well.
First test's on Es-Hail Narrow SSB transponder compared to my old regular sat-tv LNB clearly is showing more signal stability overall.
It does need some time for both the tuner and LNB to get stable, but that's only a few minutes.
Weather conditions shows less "drifting" of the pll where the old LNB was very sensitive of temperature changes, clouds before the sun did have immediately effect on the signal stability.
Some days with storms reception was impossible on SSB Narrow band.
Winter is coming over here so it gets a lot colder and more storms, but I don't expect any problems with this LNB.
Wideband testing DATV reception also shows a more stable signal although its a wider signal then narrowband, it also did increase the signal, e.g. a signal lock happens much faster.
More information about Happysat's setup and his use of the Bullseye QO-100 LNB can be found on his QO-100 website.
Evariste (F5OEO) has just announced the release of an update to RPiTX which allows it to now be used on a Raspberry Pi 4. If you are unfamiliar with it, RPiTX is a program for Raspberry Pi single board computers that allows you to transmit almost any type of signal on frequencies between 5 KHz up to 1500 MHz with nothing more than a piece of wire connected to a GPIO pin. Evariste also notes that the new version is compatible with the beta 64-bit version of Raspbian.
Some examples of signals you can transmit with RPiTX include a simple carrier, chirp, a spectrum waterfall image, broadcast FM with RDS, SSB, SSTV, Pocsag, Freedv and Opera. You can also use an RTL-SDR to record a signal, and replay the IQ file with RPiTX. However, please remember that transmitting with RPiTX you must ensure that your transmission is legal, and appropriately filtered.
Over on YouTube a few more videos showing the new AM and FM co-channel cancelling algorithms available in recent versions of SDR# have been uploaded. In the first video YouTuber channel "Peter .DXChannel" shows an example of broadcast FM Sporadic E signals (temporary long range reception due to Tropospheric ducting) being recovered with the FM co-channel canceller.
A demonstration of the SDRsharp FM Co Channel Canceller with Es signals
In the second video "icholakov" shows the AM co-channel canceller recovering a weaker signal being broadcast directly on top of a stronger one (zero carrier offset).
SDR Sharp Co-channel interference AM canceller. Several tests using Airspy HF+ Discovery
Over on his blog Ian Renton has posted about his dual plane and ship tracker project that he's titled "Plane/Sailing". The project consists of several elements including one FlightAware Pro Stick and Pimoroni ADS-B antenna for the aircraft tracking, and an RTL-SDR Blog V3 dongle and Diamond X-50 AIS antenna for the ship tracker.
Ian runs each dongle on a seperate Raspberry Pi. For aircraft the dump1090 software is used to decode the data, and it passes that data to multiple aggregator feeders such as FlightAware, FlightRadar24, ADS-B Exchange and OpenSky. For ships he uses rtl_ais which feeds into AIS Dispatcher which in turn feeds multiple marine aggregators such as Marine Traffic, VesselFinder, AIS Hub, Pocket Mariner and Ship Finder.
His system also feeds a personally hosted web front end based on his umid1090 software. umid1090 is a replacement for dump1090's web interface, the main difference being that the map is presented using military symbology. For the "Plane/Sailing" project he also extended umid1090 to be able to read the AIS ship position data from AIS Dispatcher's KML output file, and created a clean dark interface. The result is a slick looking map displaying both the tracked aircraft and ships. Ian's web interface for his system is public, and can be viewed at planesailing.ianrenton.com.
The Plane/Sailing Web Interface (Based of UMID1090)
Simple dPMR decoder. No external dependencies, no settings, uses SDR # audio path. Designed for listening to unencrypted dPMR channels.
To install the plugin simply copy the dll's from the zip file into the SDR# folder, then copy the line from the magline.txt text file into the plugins.xml file which can be opened with any text editor.
We note that there is also an open source version of DSD which includes a dPMR decoder which we posted about here.
