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.

New blog post: Tianwen-1 second apoapsis raise. For a second time in a short while, Tianwen-1 has performed an apoapsis raise manoeuvre two days ago. The delta-V for this burn was 25 m/s. Read more: destevez.net/2025/01/tian...

New blog post: Tianwen-1 apoapsis raise. With @amsat-dl.bsky.social and Bochum observatory we've been receiving telemetry from Tianwen-1 for multiple years now, and monitoring its state vectors. The orbiter has been for more than 3 years in a remote sensing orbit without any manoeuvres.

Proof of concept for sweepfft (480Mhz span) using plutosdr and modified maia-sdr hdl design. Still some work to do for interface, but hope a good start.

New blog post: 5G NR PBCH. In this post I explain how to decode the Physical Broadcast Channel in 5G. This contains the Master Information Block, which is the first piece of data that a phone decodes after synchronizing to a cell. It contains basic configuration about the cell.

Yes! We received Voyager 1 on the Dwingeloo telescope! Not bad for a telescope from 1956 and spacecraft from 1977 📡🛰️ More at www.camras.nl/en/blog/2024...

Just released a new stable Maia SDR firmware for Pluto and Pluto+ that includes these geolocation features. The firmware also includes SSL certificates that are generated at boot for HTTPS. Take a look at the installation instructions if you want to use this feature.

I'm adding geolocation in SigMF metadata to Maia SDR. The HTML5 geolocation API is used to get the position from a mobile device's GPS and other sensors. This is how the feature looks like. The geolocation is opt-in and can be cleared at any time.

New blog post: Hera telemetry. An in-depth analysis of the telemetry I received with the Allen Telescope Array just after launch. The telemetry uses TM Space Data Link frames with Space Packets and ECSS PUS v2. There are 3 virtual channels in use.

New blog post: Decoding Hera. I report about the recordings I did of the Hera X-band telemetry with the Allen Telescope Array shortly after launch and show how to decode them with GNU Radio.

New blog post: Europa Clipper telemetry. A detailed analysis of the telemetry decoded from the recording I did with the Allen Telescope Array shortly after launch. I go over the contents of each virtual channel and APID.

New blog post: Decoding Europa Clipper. A summary of my observation with the Allen Telescope Array after the launch, including a GNU Radio decoder and the IQ recording. Some highlights: the modulation and coding is PCM/PM/NRZ r=1/6 Turbo with 1115 byte frames.

We are tracking Europa Clipper with one 6 meter antenna at the Allen Telescope Array. Massively strong telemetry signal. Interestingly for such a low rate telemetry signal, there is no subcarrier.

I've implemented a spectrum display for the Maia SDR waterfall. I'd like feedback about the UX (is it readable?, is it functional?, is it obvious?...). Head over to maia-sdr.org/waterfall-de... to try it in your browser.