I am doing some BER simulations with GNU Radio (stay tuned for the next post), and during my experiments I have stumbled upon a bug in the “Decode CCSDS 27″ block. This block is a Viterbi decoder for the CCSDS convolutional code with \(r=1/2\), \(k=7\) (note that the convention used by this block is first… Continue reading Degradation bug in GNU Radio “Decode CCSDS 27”
Results for "CCSDS"
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Coding for HIT satellites (and other CCSDS satellites)
The Harbin Institute of Technology satellites LilacSat-2, BY70-1 and the upcoming LilacSat-1 all use a concatenated code with an \(r=1/2, k=7\) convolutional code and a (255,223) Reed-Solomon code according to the CCSDS TM Synchronization and Channel Coding blue book specifications. The GNU Radio decoder gr-lilacsat by Wei BG2BHC includes a custom implementation of the relevant… Continue reading Coding for HIT satellites (and other CCSDS satellites)
LTE downlink: PDSCH
This post is a continuation of my series about LTE, where I decode a recording of the downlink signal of an eNB using Jupyter notebooks written from scratch. Here I will decode the PDSCH (physical downlink shared channel), which contains the data transmitted by the eNB to the UEs, including PDUs from the MAC layer,… Continue reading LTE downlink: PDSCH
Decoding Queqiao-2
Queqiao-2 is the second Chinese lunar relay satellite. It was launched on March 20 from Wenchang, and it carries a large 4.2 m deployable dish for communications on X-band with assets on the lunar surface (up to 10 simultaneous channels, according to Wikipedia). The satellite will be placed on a frozen elliptical orbit that gives… Continue reading Decoding Queqiao-2
Decoding IM-1
IM-1, the first lunar lander mission from Intuitive Machines, also called Odysseus, was launched on February 15 from KSC, and landed on February 22 near Malapert crater, in the lunar south pole region. The mission has been a partial success. The vehicle did not manage to land upright, and broke one of its legs due… Continue reading Decoding IM-1
Trying to decode LEV-1
LEV-1 is a small lunar hopper that was carried by the SLIM lunar lander. It was released a few metres above the surface on January 19, as part of the lunar landing of SLIM. LEV-1 transmits telemetry in the 435 MHz amateur satellite band (it has an IARU satellite coordination approval), and also in S-band.… Continue reading Trying to decode LEV-1
Decoding Peregrine Mission One
Peregrine Mission One is a lunar lander built by Astrobotic Technology. It is the first mission to be launched under the NASA Commercial Lunar Payload Services program, and Astrobotic’s first mission. It was launched in January 8 from Cape Canaveral in the maiden flight of ULA‘s Vulcan Centaur. Shortly after the launch, the team detected… Continue reading Decoding Peregrine Mission One
Decoding MOVE-II
MOVE-II is a cubesat from Technical University of Munich that was launched in December 2018. It transmits telemetry in the 145 MHz amateur satellite band using a protocol that uses CCSDS LDPC codewords. Back in the day, there was a GNU Radio out-of-tree module developed by the satellite team to decode this satellite. Given the… Continue reading Decoding MOVE-II
ssdv-fec: an erasure FEC for SSDV implemented in Rust
Back in May I proposed an erasure FEC scheme for SSDV. The SSDV protocol is used in amateur radio to transmit JPEG files split in packets, in such a way that losing some packets only cases the loss of pieces of the image, instead of a completely corrupted file. My erasure FEC augments the usual… Continue reading ssdv-fec: an erasure FEC for SSDV implemented in Rust
Psyche telemetry
In my previous post I spoke about the recording of the telemetry signal from the Psyche spacecraft that I made just a few hours after launch with the Allen Telescope Array. In that post I analysed the physical aspects of the signal and the modulation and coding, but left the analysis of the telemetry frames… Continue reading Psyche telemetry