NAVigation with Indian Constellation (NavIC) (previously known as IRNSS) is an Indian navigation system consisting of 7 satellites in geosynchronous and geostationary orbits above India. It is intended for both public and military use, with a public resolution of up to 20m, and military resolution of up to 1m. After a few set backs, the satellite constellation was completed in April 2018.
Over on his blog Radiojitter, Priyasloka has put up a post showing how he was able to receive and decode the IRNSS/NAVIC satellites. To do this he uses an RTL-SDR with a GNSS antenna connected, and a modified version of the MATLAB GPS code found in this previous post, and in SoftGNSS. His post first goes through how he was able to decode and receive GPS, then goes over the technical details of the NAVIC signal, and then shows some result screenshots where he was able to determine his location with both GPS and NAVIC.
Priyasloka writes that he hasn't uploaded the modified code yet, but he plans to do so soon.
NavIC positioning results received with an RTL-SDR
Over on CrowdSupply LimeMicro are currently preparing to crowdfund their next project called 'LimeRFE'. LimeRFE is an RF front end power amplifier with filtering. It is designed to be used in conjunction with a LimeSDR or LimeSDR Mini. The LimeSDR and LimeSDR Mini are 12-bit TX and RX capable SDRs that were crowdfunded in the past. The LimeSDRs appear to be mostly aimed at cellular/industrial/commercial use cases, but there have been efforts (mostly from Marty Wittrock) to make the LimeSDR useful for ham radio.
For ham radio usage the LimeRFE front end module contains band filters for the HF band (1.6 - 30 MHz), the 2m band (144 - 146 MHz), the 70cm band (430 - 440 MHz), the 23cm band (1240 - 1325 MHz), the 13cm band (2300 - 2450 MHz) and the 3300 - 3500 MHz band. They do note that for HF use, additional filtering may still be required. On these bands the power amplifier is capable of boosting the power up to a P1 point of 35 dBm on the lower bands down to 26.5 dBm at 3 GHz.
The LimeRFE is not yet available for CrowdFundng as it is still in the prototype stages, but they note that the board is close to being finalized. You can sign up to be notified of when the board is ready on the Crowd Supply page.
RadioCapture.com is a website run by Matt Mills that is capable of automatically capturing trunked radio communications from various agencies such as the emergency services and creating publicly accessible historical and live logs of the audio. This is a concept different to radio scanner streams, as all audio is logged and historical audio can be accessed easily at any time.
The system is based on SDR hardware such as the RTL-SDR. Currently Matt runs a receiver in Denver and captures Denver PD which can be listened to on the site without needing to log in. Once logged in (registration is free), other talkgroups available include various agencies in Colorado, New Jersey and Pennsylvania.
RadioCapture.com: Currently available talkgroups being logged
Recently Matt has put a call out for people to help support the site via Patreon. He notes that RadioCapture is currently run as a hobby, but with monetary support he hopes to be able to expand the site into a business and have receivers listening and uploading worldwide. He writes:
Hey! Thanks for supporting the continued operation and development of Radiocapture.com. This is a hobby project I've been working on this since late 2011. I'd like to turn it into a real business with your help.
Radiocapture.com is a software defined radio system I built that captures entire trunked radio systems. It demodulates and captures every call on every channel of one, or many systems.
A single RadioCapture server can capture hundreds of simultaneous voice transmissions and a bunch of sites, additionally it's designed in such a way that it can run across multiple computers. My biggest RF site uses 3 machines to capture 19 P25 systems, and easily hits more than 100 active voice channels recordings simultaneously every day.
Matt has also noted that if the site is able to become self-sustaining via Patreon, he hopes to also be able to bring out a RadioCapture kit consisting of 10-16 RTL-SDR dongles, hubs and cables which would allow anyone to easily capture and upload almost all trunked communications from their area. He also notes that at the time of writing:
RadioCapture has 701790271 unique recordings of 503779875 unique transmissions (some calls get captured on multiple transmitters) from the 21 systems that have been captured
If you're interested in talking to Matt about the site, you can also join his Rocket.Chat room at radiocapture.chat.
Corrosive from the SignalsEverywhere YouTube channel has recently released episode two of his new podcast. This episode is titled "Common SDR Mistakes and How to Resolve Them". In the podcast Corrosive discusses some tips like how to ensure that the gain on your SDR is set correctly, how to set the sample rate, how to optimize the waterfall display, and what antennas to use. Later he goes on to talk about our RTL-SDR Blog V3 dongles, and discusses some posts from our blog.
Thank you to Dimitris for submitting his article on creating an RTL-SDR based EMC probe. An EMC probe is a device that can be used to detect electromagnetic interference leaking from areas on electronic devices. For example an electronic PCB might have problems with RF leaking into other components. With the probe you could determine where the leak is coming from.
To create the probe he uses a 30cm semi-rigid coax cable and an RTL-SDR dongle. The semi-rigid coax is cut in half, the center conductor stripped back, then looped around on itself and soldered to the shield. Dave from EEVBlog did a video on this previously which is what inspired Dimitris. The next steps are simply to connect the probe to an RTL-SDR, put it into direct sampling mode and probe around for signals. Note that an RTL-SDR with direct sampling like our V3 model, or an RTL-SDR with upconverter is required to receive signals below 24 MHz.
His results show that he was able to successfully probe an OCXO oscillator, by seeing the 10 MHz signal in SDR#. The rest of his post goes on to discuss the limitations of this method, and compares it against professional EMC probes available on the market.
Over on Reddit freelance investigative journalist Emmanuel Freudenhal has put up a very interesting post about how he is using ADS-B tracking to keep an eye on the travel habits of dictators around the world. If you were unaware, ADS-B is a signal transmitted by aircraft which contains aircraft ID info, and data such as speed, altitude and GPS location. Websites like ADS-B Exchange aggregate ADS-B data from volunteer ground stations that are running (mostly) RTL-SDR dongles. Emmanuel notes that by watching the movements of aircraft registered to dictators, it is possible to keep an eye on their travel habits.
One story that Emmanuel has written using this data is a piece on Paul Biya, Cameroon's president. His article discusses how Paul Biya is often seen in Geneva Switzerland, away on private visits. In a comment, Emmanuel notes that since his story ran, Paul Biya has almost stopped travelling to Switzerland.
Emmanuel has also been running a Twitter bot that uses ADS-B data to automatically tweet when a dictator aircraft is detected at Geneva airport. A list of known dictator aircraft is kept on a publicly accessible Excel file.
Now he is hoping to expand his tracking operation, and is asking for more people to feed the ADS-B Exchange aggregation website. ADS-B Exchange is the site recommend to feed because it is the only ADS-B aggregation website that does not censor any aircraft. Other aggregation sites such as Flightradar24 and FlightAware have come under scrutiny in the past for their willingness to upon request censor and block the tracking of military/political aircraft and private jets owned by several companies. In particular several aircraft owned by dictators are reportedly censored. However, the counter argument is that not censoring aircraft may result in ADS-B tracking eventually being made illegal, or that costly legal suites may be brought against ADS-B aggregation companies.
I'm a freelance investigative journalist (www.emmanuel-freudenthal.com / @emmanuelfreuden). I'm getting into SDR/ADSB and very glad I found this group because I need your help to track aircrafts!
With a colleague, we started a project to look into the travels of dictators around the world. It's an evolution of a Twitter bot (https://twitter.com/GVA_Watcher) started a few years ago. This bot tweets every time an aircraft owned by a dictatorship lands or takes off at the Geneva airport, Switzerland. And dictators visit Geneva, a lot. There's secretive banks and good healthcare, enjoyed by Algeria's departing president or Cameroon's president Paul Biya.
We want to expand this project to all of the world's airports. See our place-holding website: https://dictatoralert.org(which will get expanded soonish). To do so, we've partnered with ADSB-Exchange, which as you probably know, is the only website that doesn't censor flights. Usually the planes owned/chartered by dictatorships don't show up on flightaware or flightradar24 (anyone can asked to be removed). Some planes also don't share their GPS coordinates (e.g. Mode S) and so they don't show up.
In addition to the Dictator Alerts, we'll also use the data to do investigations into dictatorships, human rights violation and corruption.
The idea is to allow everyone to keep tabs, so the data will be available publicly, via Twitter bots and on a dedicated website (with e.g. a page per dictatorship and per airport).
To succeed, we need a lot more antennas! So, it'd be great if you could feed ADSB-Exchange. You can do that in addition to feeding other services. See how to do it here: https://www.adsbexchange.com/how-to-feed/ If you want to feed, please contact me on [email protected], my twitter DM are open. It's quite important that you contact me before feeding, so that we also capture aircrafts that don't share their GPS coordinates.
That also means, you'll be able to see ALL of the data that you're collecting online.
What do you think? Would you be keen to participate? Any questions?
Your feedback is very welcome, i'm still learning!
Best,
Emmanuel
Dictator Alert. A Twitter bot reporting on dictator movements via ADS-B data. dictatoralert.org
Over on YouTube user Techminds has uploaded a video that shows how he is using a Raspberry Pi Zero to transmit WSPR. To do this he uses the WsprryPi software which allows you to transmit WSPR by connecting an antenna directly to a GPIO pin on the Pi Zero. With this no extra hardware is required, although a filter is highly recommended to reduce spurious emissions from harmonics.
In his test Tech Minds directly connected the Pi Zero to an unun and HF wire antenna and ran WsprryPi. His results showed that even with the tiny 10mW output power of the Pi Zero's GPIO port his WSPR messages were able to reach several receivers halfway across Europe, and even to Iceland and Morocco from his home in the UK.
WSPR is an amateur radio digital HF mode designed to be decodable even if the signal is transmitted with very low power and is very weak. It can be used to help determine HF radio propagation conditions as WSPR reception reports are typically automatically uploaded to wsprnet.
WSPR - Weak Signal Propagation Reporter - From A Pi Zero ?
Over on his YouTube channel SignalsEverywhere, Corrosive has uploaded a new video about setting up a KerberosSDR for direction finding. KerberosSDR is our new 4-input Coherent RTL-SDR that was crowdfunded on Indiegogo, and has now shipped to all backers. With KerberosSDR applications like direction finding and passive radar are possible. If you're interested, there are still about 70 units available in this batch. After that a second batch will be available in a few months.
In the video he goes over the full set up procedure, from setting up his chosen computing platform (a Raspberry Pi 3) to connecting up the KerberosSDR, connecting to it's web interface, calibrating, setting up the antennas, and then demonstrating some direction finding with four whip antennas on his car and a HackRF used as a signal source.
Radio Direction Finding Equipment KerberosSDR Coherent 4 x RTL SDR RDF Setup
