New blog post: Notes on debugging Rust microcontroller stack usage. This is story about low-level debugging of a RISC-V baremetal application that was running out of stack depending on the compiler options.

I've released gr-satellites v5.9.0. gr-satellites is a collection of GNU Radio decoders for amateur satellites. This release adds support for recently launched satellites, as well as new blocks that can be used to put together an AX100-compatible modem with CSMA.

New blog post: First analysis of the Lunar GNSS Receiver Experiment data. I have developed a high-sensitivity GPS acquisition algorithm in CUDA and ran it on the experiment datasets. 1 to 3 satellites are detected in 60% of the recordings.

I've added SatYAML (configuration) files to gr-satellites for 24 satellites launched during 2025 that transmit on amateur radio spectrum. I'd like to request help from the community to keep gr-satellites updated with new launches, as it is hard for me to keep track of everything.

New blog post: Decoding ESCAPADE. Here I decode a recording of the ESCAPADE spacecraft that I did with an Allen Telescope Array antenna the day after they were launched. The modulation is PCM/PSK/PM with rate=1/2 Turbo code. The telemetry uses CCSDS TM frames and Space Packets.

I have made a new release of the Maia SDR firmware. This is a maintenance release that updates dependencies and includes some USB Ethernet connectivity improvements to Android devices.

New blog post: sigmf-toolkit. I present a new Python package I've made and showcase one of its tools, which adds to a SigMF file annotations for each packet in a PCAP file. This is a good way of doing protocol analysis and debugging across the physical and upper layers. destevez.net/2025/11/sigm...

New blog post: Non-coherent m-FSK BER. Another short post in which I derive the following formula for the symbol error rate of non-coherent m-FSK and validate it using simulations. destevez.net/2025/10/non-...

New blog post: Non coherent FSK BER. A short note on how to compute the well known formula for the bit error rate of FSK, because I can never quickly find a source which contains this derivation. destevez.net/2025/10/non-...

New blog post: 10 years of blogging. Today it's 10 years since I wrote the first post in my blog. To celebrate I've made a summary of what I have been posting during these years. It can serve as a good index for people who are not too familiar with the blog's contents. destevez.net/2025/10/10-y...

New blog post: Synthetic aperture radar autofocus and calibration.

Would you like to work in RF signal processing at Muon Space for SIGINT and RF science missions with a team of great engineers including myself? If you are eligible to work on ITAR/EAR and interested in helping us grow our cloud-based and onboard processing, my DMs are open.

Synthetic aperture radar vs Gopro.

New blog post: Flip-flop timing experiments. I design an ASIC flip-flop using Magic and play around with some ngspice timing simulations of output delay, setup and hold. I have made my flip-flop (top) as small as possible, so it is half the area as the standard cell (bottom).

New blog post: 10 GHz FMCW radar LO board. I've finished assembling and testing my ADF4158+HMC391 3.9-4.45 GHz LO board, for which I asked for reviews a few months ago. In the post I explain some aspects of the board design, and the software I've written and testing I've done.

New blog post: Multispectral analysis of the Tres Cantos wildfire with Sentinel-2 data. This image shows vegetation surviving the fire in green, vegetation lost by the fire in magenta, and areas affected by the fire but with less vegetation loss (dry grass) in blue.

On Monday there was a large wildfire in Tres Cantos, Madrid, Spain, which is where I live (my family, friends and I are all okay). Today I have found some Airbus Space Pléiades Neo imagery that shows the extent of the fire more accurately than all other source I've seen.

I've made new releases of gr-satellites: 5.8.0 (GNU Radio 3.10), 4.15.0 (GNU Radio 3.9), 3.22.0 (GNU Radio 3.8). This will be the last release supporting GNU Radio 3.9 and 3.8. Maintainance for these branches will stop now.

New blog post: n78 band 5G NR recordings. I comment on some recordings I have made that are representative of the current state of 5G deployment on this band in Spain (100 MHz cells for Movistar and Orange, 90 MHz cell for Vodafone).

Wrote code for SAR image antenna pattern normalization and polarimetric calibration (channel imbalance and crosstalk). Image looks very nice now.

Some months ago I shared my design of a PCB with an ADF4158 PLL/waveform synth and HMC319 VCO intended as an LO source for an FMCW radar in the 10 GHz band. I have finished soldering all the components, and the HMC319 appears to be working. The next step is the ADF4158 config.

New blog post: Galileo OSNMA chain renewal. OSNMA is the Galileo open service navigation message authentication system, which authenticates cryptographically the navigation data broadcast by the satellites. Here I comment on a TESLA chain renewal test done on Tuesday.

New blog post: About FLLs with band-edge filters. This post is motivated by some bugs in the @gnuradio.org FLL that I've been working on fixing. I explain what band-edge filters are, and how they can be used in an FLL.

New blog post: Z-Sat VHF transmissions. Recently Daniel Ekman has noticed that Z-Sat, a Japanese satellite launched in 2021 that has an amateur radio payload, is transmitting a digital signal continuously. Here I analyze a recording of this signal.

New blog post: 5G NR PDSCH. In this post I show how to decode the 5G PDSCH (downlink data) by using the SIB1 from an srsRAN gNB recording as an example. I go into the details of how LDPC and the rest of rate matching and other encoding work.

Found motivation to write some SAR processing code. Fast factorized backprojection generates several small polar format images and then interpolates them to one big image. It's faster, but has slightly worse image quality due to all the interpolations.

Measuring Radio Recombination Lines (RRL) with the Dwingeloo telescope (@radiotelescoop.bsky.social), in the Omega Nebula (M17/W38).

New blog post: 5G NR PDCCH. In this post I show how to decode the Physical Downlink Control Channel, by using as example the PDCCH for the SIB1 in a srsRAN gNB recording. The PDCCH is used to transmit control information such as downlink scheduling and uplink grants.

New blog post: Time-dependent delay in @gnuradio.org. I have added a new block to gr-satellites that performs a time-varying delay. This block works similarly to the Doppler correction block: the delay versus time is defined by a text file prepared beforehand.

Is there anyone using gr-satellites in GNU Radio 3.8 or 3.9? What would be the impact of stopping gr-satellites releases for these GNU Radio versions? I'm considering dropping support for the maint-3.9 and maint-3.8 branches, since these cause more trouble each day.

At the beginning of March, I published a post studying the S-band Doppler of Blue Ghost Mission 1's lunar landing, using recordings by @amsat-dl.org Bochum Observatory and @radiotelescoop.bsky.social. I got an unexplained difference of 55 Hz between both stations, after correcting for Doppler.

A week ago I posted here a PCB design I've been working on with an ADF4158 and HMC391 for the LO of an FMCW 10 GHz radar. Thanks to all who reviewed this and sent suggestions. I have now switched to a 4-layer FR4 stackup, added M2 mounting holes and done other tweaks.

New blog post: Analysis of the CAMRAS Venus radar experiment. A deep dive into the Earth-Venus-Earth L-band radar experiment done in March by @radiotelescoop.bsky.social, Astropeiler Stockert, the Deep Space Exploration Society, and Open Research Institute. 🧵

I've been designing a PCB with an ADF4158 and HMC391 that generates a 3.9 - 4.45 GHz LO for an FMCW radar. The idea is to use this with a subharmonic mixer to build a radar in the 10 GHz amateur band, inspired by the ADALM-PHASER but much cheaper.

A bit late, but here is some additional analysis of the Earth-Venus-Earth radar experiments with @radiotelescoop.bsky.social from March 22nd, 2025. It takes the 4 recordings at the Dwingeloo and Stockert telescopes and searches in Doppler frequency and Doppler rates for the radar reflections.

Highly recommend even if you don't code in Rust but want to understand how atomics and memory orderings work.

We used the historic Dwingeloo telescope to bounce a signal off the surface of Venus, and receive its echo! This marks only the second time that amateurs have achieved an 'EVE' (Earth-Venus-Earth) bounce. Venus was about 40 million kilometers from Earth. www.camras.nl/en/blog/2025...

New blog post: Decoding BGM-1 GMSK telemetry. Here I show how to decode the coherent GMSK telemetry transmitted by @firefly-aerospace.bsky.social Blue Ghost Mission 1. I start reviewing the math of the Laurent decomposition, which allows to approximate GMSK as OQPSK with an certain pulse shape.

The spectrum on the right is an interesting reminder that GIOVE used plain BOC(1) for the open service modulation, instead of the fancier CBOC used by the later Galileo satellites.

As ever, the data recordings from @radiotelescoop.bsky.social are public and can be downloaded. bsky.app/profile/radi...

New blog post: BGM-1 Doppler during the lunar landing. Some quick plots of the Doppler of @firefly-aerospace.bsky.social's lander as received by the @amsat-dl.org and @radiotelescoop.bsky.social groundstations.

With the #BGM-1 lander from @firefly-aerospace.bsky.social now safely on the surface of the Moon, we've had some time to take a closer look at the @radiotelescoop.bsky.social's observation of the #BGM-1 signal during the landing, which shows several events during the landing sequence.

New blog post: Coding NEON kernels for the Cortex-A53. In my talk about qsdr I briefly showed a hand-written assembly NEON kernel for the Cortex-A53 that is 2x faster than code generated by LLVM from Rust or C++. Here I explain the details and tricks that went into this kernel.

Testing again Galileo OSNMA on a small RISC-V microcontroller. Bob N6RFM wanted some help troubleshooting his system, so I built and tested a known-good firmware image for him. The Galmon data feed is down, so I'm using my own uBlox receiver.

A new stable version of gr-satellites has been released for GNU Radio 3.10, 3.9 and 3.8. This adds support for recently launched satellites and a few other minor improvements and features.

The recording for my #FOSDEM talk "Yet another new SDR runtime?" is now up. In this talk I speak about high-performance SDR runtimes in embedded systems, and present an experimental runtime I have been writing in Rust.

New blog post: decoding HYDRA-T. Here I show that this commercial satellite from Hydra Space that is transmitting in the amateur satellite 435 MHz band uses the same modulation, coding and telemetry format as HADES-R, an AMSAT-EA satellite launched at the same time.

I'll be all Sunday roaming around FOSDEM. If someone wants to meet, just ping me.

New blog post: Decoding IEEE 802.11ah. Here I analyze a recording of a baby monitor camera, which happens to use 2 MHz BW WiFi HaLow at 866 MHz. Similarly to my LTE and 5G posts, I write a Jupyter notebook to decode the signal from scratch, and write the MAC frames to PCAP.

Today January 12, 2025 #Mars is on closest approach with #Earth at 96.08 million km. Next Mars clostest to Earth is on February 20, 2027 with 101.41 million km. Perfect time to listen to Mars on X-Band, even with a smaller antenna.