Akos the author of the radioforeveryone.com blog has recently added two new articles to his blog. The first post is a comprehensive guide to setting up your own ADS-B station. The guide focuses on creating a system that is easy to use, has good performance and is value for money. In the post he shows what type of computing hardware is required, what software can be used and what RTL-SDR dongles work best. He also shows what choices are available when it comes to amplification and filtering to improve signal reception and goes on to talk a bit about adapters and the antennas that work best for him.
First generation (1G) mobile phone technology was brought out in the 80’s and was an unsecured analogue system. These days 1G technology is completely phased out in favor of digital standards like 2G (GSM), 3G and 4G LTE and so those old 1G handsets are now useless. However, at Shmoocon 2017 presenter Brandon Creighton delivered a talk where he showed how to use a TX capable SDR like a USRP or HackRF to create your own home 1G system that allows those old brick phones to be useful once again.
The actual video of the conference talk won’t be available online until about half way through the year but the blurb read:
AMPS, the first widely deployed cellular network in the US, was old enough that it had been designed by pre-breakup Bell, yet robust enough to survive for decades in service. Unlike LTE or even GSM, it was also a protocol simple enough to be described in a fairly short specification; if you wanted to you could listen to calls with a TV tuner (or modified phone).
This is a talk on the design and implementation of gr-amps, a set of GNU Radio blocks that can turn a TX-capable software-defined radio into a base station for AMPS devices–including that brick phone in your basement. No background in SDR is necessary to follow along (but it doesn’t hurt).
Expect detours into near-forgotten phreaker history: the weaknesses that enabled phone cloning, the efforts of wireless carriers and the US government to fight exploitation, and more.
The GNU Radio code to run your own AMPS (1G) system is available on GitHub. It has been tested on a USRP and HackRF.
The existing thermostat wireless receiver is a Danfoss RX2. In order to reverse engineer the protocol Andy opened up an older that one he had and saw that it used an Infineon TDA5210 RF receiver chip. Armed with this part number he was able to look up the datasheet and determine the operating frequency. Then by using an RTL-SDR he captured some packets while pressing buttons on the thermostat transmitter and piped the audio file into audacity, where he was able to clearly see the digital waveform.
Andy then wrote a Python program using the ‘wave’ library, which allowed him to easily read binary values for a .wav file. With his code he was able to extract the data from the signal and determine the preamble, sync word, thermostat ID and the instruction code (on/off/learn).
In a future post Andy hopes to show us how he’ll use an RF69 module with an Arduino to actually control the thermostat using the reverse engineered packet knowledge.
Over on our YouTube channel we’ve uploaded a new video that shows how bad the interference from Ethernet over Power devices can be. Ethernet over Power, Powerline Networking, Powerline Communications or ‘HomePlug’ is a technology that allows you to use any of your household power outlets as an internet Ethernet port, completely eliminating the need for runs of Ethernet cabling. They are capable of high speeds and can be used anywhere in the house assuming the two plugs are on the same power circuit.
Unfortunately these devices tend to wipe out almost the entire HF spectrum for anyone listening nearby. As household powerline cables are not shielded for RF emissions they radiate in the HF spectrum quite heavily. In the video we demonstrate what the HF spectrum looks like with one of these devices used in the house. The particular device used was a TP-Link brand adapter, and a WellBrook Magnetic Loop antenna was used outdoors, with the null facing the house. An Airspy R2 with SpyVerter was used to view the spectrum.
The video shows that even when the network is idling there are several brief bursts of noise all over the spectrum. Then when a file is downloaded almost the entire spectrum is completely wiped out.
Interestingly from the video it appears that the amateur radio frequencies are actually carefully notched out and those frequencies remain relatively clean. Most manufacturers of these devices appear to have worked with the ARRL to please ham radio enthusiasts, but SWLers will likely be in trouble if any of these devices are used in your house or neighbors house.
Over on his radioforeveryone.com blog, author Akos has uploaded three new posts. The first post briefly explains visually what is meant by line of sight when it comes to radio signals. Essentially at UHF and higher frequencies the radio antenna needs to be able to ‘see’ the transmitter, meaning that any blockages such as trees, houses etc will block the signal.
In his second post Akos briefly explains why USB cable quality can matter when it comes to SDRs. He shows that some USB cables tend to pick up more interference than others.
Finally in his third post Akos reviews the Uputronics 1090 MHz Filtered Preamp. Uputronics is a UK based company that sells various filtered LNA’s. Akos writes how he’s very impressed with the premium packaging, look and feel of the device and thickness of the metal case. In performance tests the preamp together with a V3 dongle with bias tee power clearly improves ADS-B position reports significantly. We note that we also have 1090 MHz filtered preamp from Uputronics (an older model), and can also highly recommend their products.
The LimeSDR is a RX/TX capable SDR with a 100 kHz – 3.8 GHz frequency range, 12-bit ADC and 61.44 MHz bandwidth. Back in June 2016 they surpassed their $500k goal, raising over $800k on the crowdfunding site Crowdsupply.
We predict that the LimeSDR will essentially be seen as an improved HackRF SDR, perfect for experimenting with and reverse engineering RF devices without the 8-bit ADC, poor sensitivity and half-duplex limitations of the HackRF. They also seem to be active in promoting software for the device, writing that they will eventually have an app store like marketplace for various LimeSDR apps.
Shipping Will Start in 24 Hours The first batch of LimeSDRs and accessories has arrived safely at the Crowd Supply warehouse.
Address Changes Must Be Processed Now
Shipping of the first batch of orders will commence within the next 24 hours. If you need to change your address, you should do it now by logging into your Crowd Supply account and viewing your order.
When Will My Order Ship?
The only way to know to know with certainty if your order is shipping within the next few days is if you receive a shipping confirmation email from Crowd Supply. The logistics of shipping hundreds of varied orders around the world is complex enough that it’s not possible to tell you your exact place in line. For example, Crowd Supply will likely send several test shipments to different countries to gauge how well they get through customs and the timing of future shipments to those countries may be affected by the results.
When Will My Order Arrive?
Once your order has shipped, you will receive a shipping confirmation email with a tracking number. For orders destined for outside the US, it is not uncommon for the tracking information to cease being updated after it leaves the US, though for some countries (e.g., UK, Germany, Australia) the packages can continue to be tracked using your national postal website and the same tracking number. If there is a delay in delivering your package, you should check with your local customs office to make sure they are not holding it and waiting for you to pick it up.
We look forward to beginning to use our own LimeSDR and will post reviews when it arrives.
Over on our new YouTube channel we’ve uploaded a video comparing the SDRplay RSP1 and RSP2 on reception of Non-Directional Beacons at around 350 kHz. Both radios had their gains adjusted for the best possible SNR and reception. They were connected through a splitter to a Wellbrook Magnetic Loop antenna. The Hi-Z port on the RSP2 was used as Port A and Port B don’t have good reception below about 1 MHz.
In all tests the RSP2 appears to have the better SNR, a lower noise floor and thus better audio, though from the spectrum view the RSP1 seems to have a little less spurs.
Subscribe and keep an eye on our new YouTube channel as soon we’ll be uploading more RSP1 vs RSP2 comparisons, Airspy vs RSP2 comparisons and other SDR related videos as well.
Bonito is a company that sells various products such as their own small active antennas. Some examples are the Bono-Whip (20kHz – 300 MHz), GigaActiv (9kHz – 3 GHz) and the MegaLoop (9kHz – 200 MHz).
Over on their blog they’ve uploaded a post titled “why even good antennas need good coax cable”. The post explains why high quality heavy shielded coax cable may be required to receive HF signals in noisy environments. The author writes how even placing an antenna in a quiet area outdoors may not work if the coax is still run through an high interference environment, such as through a house.
Typically RG58 cable is most commonly used with HF antennas. However, the author noticed that when using RG58 he was still receiving FM stations, even though the antenna that he was using was a MegaLoop with a built in broadcast FM filter. After switching his RG58 cable to H155 coax, the FM station disappeared. H155 coax is low loss and designed for GHz level frequencies, so it has much better shielding from its tighter braid.
The images below also show the difference in noise floor the author saw after replacing all his RG58 with H155 coax.