SDR# Co-Channel Canceller and Micro Tuner Updates

SDRSharp (SDR#) is one of the most popular SDR programs that is used often with Airspy and RTL-SDR devices. Recently Youssef, the developer of Airspy products and the programmer behind SDR# has again been adding new enhancements to the software that allow AM DX listeners to easily receive channels that are even on top of each other in frequency.

The Co-Channel Canceller has been in SDR# since 2020, but recently enhanced for better performance and easier use, and a 'micro-tuner' feature has been added, allowing users to easily select the overlapping channel that needs to be cancelled. 

Earlier in the year the noise canceller was also improved with a 'NINR' (Natural Intelligence Noise Reduction) algorithm that appears to be one of the best noise cancellers available in SDR software today.

Youssef's twitter @lambdaprog contains several videos demonstrating the effectiveness of the updates.

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WiFi Grid RTL-SDR Radio Telescopes featured in SARA2022 Conference Talks

Over on YouTube the Society of Amateur Radio Astronomers have recently uploaded talks from their SARA 2022 online conference. Two of the talks we've seen focus on describing results produced by small and cheap WiFi Grid RTL-SDR radio telescopes.

Back in early 2020 we first published an article about how it is possible to use get into amateur radio astronomy cheaply using off the shelf WiFi grid dishes, combined with a 1420 MHz LNA + filter, an RTL-SDR and the SDR# software with IF average plugin to measure the galactic hydrogen line.

In the SARA conference we've seen two talks expanding on the use of WiFi grids for radio astronomy. In the first talk Alex Pettit discusses how he's used a WiFi grid attached to an equatorial telescope mount, and a custom modified feed in his setup. In his talk he explains how to use the IF average plugin, and how he uses a MATLAB script to process and plot the saved data.

Alex Pettit: Galactic Hydrogen 1.42 GHz RF Emission Radio Astronomy for $300

In the second talk Charles Osborne describes his "Scope-In-A-Box" which consists of the WiFi Grid, LNA, Filter and RTL-SDR combination and compare the setup versus the same hardware used on a larger 3.7m dish.

Charles Osborne: Comparing Scope-in-A-Box to a 3.7m Dish

If you were interested in those talks, you might also want to check out the other talks from the conference, many of which also involve the use of software defined radios in the receive chain for various amateur radio astronomy experiments.

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SI-SDR-UG Recorded Livestream: Corey Explains DF-Aggregator for KrakenSDR and KerberosSDR

The South Indian SDR User Group (SI-SDR-UG) have recently held their fourth live stream conference. This conference included some interesting talks such as:

  • "Introduction to GNU Radio Series, Part 2" by Neel Pandeya
  • "Silice, a Language for Hardcoding Algorithms into FPGA Hardware" by Dr.Sylvain Lefebvre
  • "RF Geo-Location for Everyone" by Corey Koval
  • "Overview of Wireless Channels, Part 1" by Aditya Arun Kumar

In particular we were interested in Corey's talk which starts at 1:27:40 and talks about DF-Aggregator, an open source mapping program he's written for KerberosSDR, KrakenSDR and any other radio direction finding hardware that can be adapted to the software. In the talk Corey explains what DF-Aggregator is and how the clustering algorithm works.

South Indian SDR User Group (SI-SDR-UG) Live Stream Event-4

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A teardown of the early 2000’s Psion Wavefinder DAB SDR Receiver

The Psion Wavefinder was one of the first applications of SDR technology in consumer electronics. It was a Windows PC based USD DAB SDR radio receiver that released in the UK in October of the year 2000, for an initial price of £299. (In comparison RTL-SDR wasn't discovered until 2012).

Digital Audio Broadcast (DAB) is a digital replacement for analog broadcast FM. It provides high quality digital audio at the expense of higher cost receivers, and possibly greater difficulty with reception in weak or challenging RF environments. DAB is mostly only used in Europe and Asia Pacific regions, and is not found in the USA.

Due to the lack of popularity of DAB, combined with show stopping bugs in the official software (as seen in reviews), the Psion Wavefinder flopped as a product, and was promptly reduced to £49.99, and out of production by the year 2002.

Over on his YouTube channel backofficeshow, Andrew claims the Wavefinder as the first SDR Radio device and has filmed a teardown, and demonstration of the device working in a Windows XP virtual machine.

The main chips on the device consist of a CPLD DSP, RISC based USB controller, RAM and a fixed point DSP processor. According to some further information from a compatible third party Linux program called dabtools, the Wavefinder performs the COFDM demodulation in hardware on the DSP chips and then transfers the samples over USB for further SDR processing on the host computer.

Psion Wavefinder - The first SDR Radio Device

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Decoding Inmarsat STD-C with Command Line Decoder STDCDEC and SigDigger

Over on his YouTube channel Aaron has uploaded a video showing how to use SigDigger and a C based command line Inmarsat STD-C decoder called 'stdcdec' together on his DragonOS SDR based Linux OS image.

STD-C is a marine satellite service that broadcasts messages that typically contain text information such as search and rescue (SAR) and coast guard messages as well as news, weather and incident reports. With the right software, an RTL-SDR and an appropriate L-Band satellite antenna like our 'Active L-Band 1525 - 1660 Inmarsat to Iridium Patch Antenna Set' these signals can be received and decoded.

The stdcdec software provides a way for command line only systems to receive and view STD-C data. In his video Aaron shows an example setup that uses SigDigger to determine the audio frequency offset, and receive the audio which is then passed to the stdcdec software. We note that SigDigger is a GUI based program but could probably be replaced with another CLI based program, in order to run on a headless system (as long as the tuning and audio center freq is determined before hand). Aaron is hoping to explore solutions for this in the future.

DragonOS Focal Rx and Decode Inmarsat-C Messages w/ SigDigger + STDCDEC (RTLSDR)

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APT_COLOR: Add False Color to Black and White NOAA APT Images

Thank you to Sasha for submitting news about the release of their latest application called "apt_color". The most popular application for decoding APT weather satellite images from NOAA polar orbiting satellites is WXtoIMG. However, WXtoIMG is closed source and is abandonware. There are APT decoder alternatives, however unlike WXtoIMG most other open source APT decoders only provide black and white images, and do not have a false color feature.

The apt_color application can be used to turn black and white APT images received from NOAA satellites into false color images. Sasha writes:

I am working on an APT false color application here. The application is still in the very, very, early stages but still seems to produce good results. It does not need to rely on any overlays, it simply works off the data you give it - the original decoded image data. I will attach some results. NOAA-18 seems to be the best suited spacecraft for this program.

apt_color: Turn black and white NOAA images into false color
apt_color: Examples
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Rolling-Pwn: Wireless rolling code security completely defeated on all Honda vehicles since 2012

Back in May we posted about CVE-2022-27254 where university student researchers discovered that the wireless locking system on several Honda vehicles was vulnerable to simple RF replay attacks. A replay attack is when a wireless signal such as a door unlock signal is recorded, and then played back at a later time with a device like a HackRF SDR. This vulnerability only affected 2016-2020 Honda Civic vehicles which came without rolling code security.

Recently a new vulnerability discovered by @kevin2600 that affects ALL Honda vehicles currently on the market (2012-2022) has been disclosed. The vulnerability is dubbed 'Rolling-PWN' (CVE-2022-27254) and as the name suggests, details a method for defeating the rolling code security that exists on most Honda vehicles. Rolling code security is designed to prevent simple replay attacks, and is implemented on most modern vehicles with wireless keyfobs. However @kevin2600 notes the following vulnerability that has been discovered:

A rolling code system in keyless entry systems is to prevent replay attack. After each keyfob button pressed the rolling codes synchronizing counter is increased. However, the vehicle receiver will accept a sliding window of codes, to avoid accidental key pressed by design. By sending the commands in a consecutive sequence to the Honda vehicles, it will be resynchronizing the counter. Once counter resynced, commands from the previous cycle of the counter worked again. Therefore, those commands can be used later to unlock the car at will.

The vulnerability has been tested on various Honda vehicles with HackRF SDRs, and this seems to indicate that all Honda vehicles since 2012 are vulnerable.

Although no tools have been released, the vulnerability is simple enough and we've already seen people replicate results.

The story of Rolling-Pwn has already been covered by magazines and news organizations such as TheDrive, Vice, NYPost, and FoxLA.

It should be noted that when the previous replay attack vulnerability was highlighted, Honda released a statement noting that it has no plans to update its older vehicles. It is likely that Honda will not issue updates for this vulnerability either. It is possible that this vulnerability extends beyond just Honda vehicles too.

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SelfieStick: Combining noisy signals from multiple NOAA APT satellites for clean imagery

Researchers from Carnegie Mellon University have recently presented a paper detailing how they combined noisy signals from multiple passes of low earth orbit (LEO) satellites NOAA 15, NOAA 18 and NOAA 19 in order to create a higher quality image. For a receiver they used a low cost RTL-SDR Blog V3 mounted indoors with a whip antenna.

In a normal setup, weather satellite images from NOAA LEO weather satellites can be received with an RTL-SDR, computing device and an appropriate outdoor mounted antenna that has a good view of the sky. If the antenna is not suited for satellite reception, and/or is mounted indoors, at best only poor quality very noisy images can be received.  

The researchers demonstrate that it is possible to combine noisy images received over time, and from different satellites in order to generate a higher quality image. The challenge is that the different satellites and different receiving times will all produce different images, because the satellites will be at a different location in the sky each pass. They note that simply transforming the images in the image domain would not work very well for highly noisy images, so instead they have devised a method to transform the images in the RF domain. The RF signals are then coherently combined before being demodulated into an image.

The results show that 10 noisy satellite images from the indoor system are comparable to one from a comparison outdoor system. However, they note some limitations in that the system assumes unchanging cloud cover during passes. In the future they hope to extend the system to cover other modulation schemes used by other low earth orbit satellites in order to increase the number of usable satellites.

Selfiestick: Combining noisy images from multiple NOAA satellites received by an indoor RTL-SDR system.
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