- Hermes-Lite 2 external 10 MHz reference
Interested by the forthcoming HamSci December 2021 eclipse festival of frequency measurement, I have decided to enable and test the external 10 MHz input of my Hermes-Lite 2 DDC/DUC HF transceiver. This will allow me to use a GPSDO (the Vectron MD-011 which has appeared in other posts) to reference the Hermes-Lite 2 in order to measure frequency accurately.
- Decoding DART
DART, the Double Asteroid Redirection Test, is a NASA mission that launched last Wednesday from Vandenberg. The goal of this mission is to crash the spacecraft into the small asteroid Dimorphos, allowing us to measure the small change in the orbit of the asteroid caused by the impact.
From the communications perspective, this spacecraft is the first to use a Spiral Radial Line Slot Array (RLSA) as high-gain antenna. Details about the antenna design can be seen in this paper. The paper shows that antenna polarization is LHCP. Most DSN communications use RHCP, although there are a few notable exceptions (for instance Emirates Mars Mission), and the DSN stations are equipped to handle both polarizations. I’m not sure if DART is indeed using LHCP or if this is just a matter of the convention in the definition of the polarization used in the paper (there are actually two opposite conventions to define the sense of circular polarization).
A few hours after launch, as the spacecraft passed over Europe, Miguel CT1BYM and Iban EB3FRN recorded the X-band telemetry signal from DART at 8421.79 MHz. This post is a first analysis of the signal.
- Tianwen-1 remote sensing orbit
On November 8, the Tianwen-1 orbiter made a manoeuvre to move itself to the remote sensing orbit, as reported by Chinese media. This orbit is the final orbit in the mission, as depicted in this figure from Wikipedia. The main goal of this orbit is to study the geophysical properties of Mars with all the orbiter instruments (see this paper) and to continue acting as a communications relay for the rover Zhurong.
As usual, AMSAT-DL has been collecting telemetry from Tianwen-1 with the 20 metre antenna at Bochum observatory, including spacecraft state vectors. This allows us to study the orbit change manoeuvre and the properties of the remote sensing orbit. This post is a first look at the state vector data.
- An update about Lucy’s telemetry
In my previous post I presented a description of the X-band telemetry of Lucy, including a GNU Radio decoder, some recordings from the Allen Telecope Array, and an analysis of some of the telemetry received in the two days following the launch. This is a short post with some updates about the telemetry analysis of the Lucy mission.
- Decoding Lucy
Lucy is a spacecraft that will study the Trojan asteroids, during a twelve year mission. It was launched last Saturday at 9:34 UTC from Cape Canaveral on an Atlas V rocket. Its telemetry downlink is on X-band, at a frequency of 8445.768 MHz.
Iban Cardona EB3FRN made a 30 minute recording of the telemetry downlink at 19:00 UTC on Saturday, as the spacecraft first appeared over Europe after launch. r00t.cz did a brief analysis of this recording overnight, and then published some more details about the telemetry data. On Sunday, at 8:52 UTC, I did a long recording with one of the dishes in the Allen Telescope Array. This recording lasts 3 hours 26 minutes, and ends when the spacecraft set below the 16 degree elevation mask of the ATA. In this post I give a first analysis of the telemetry data in both recordings.
The recording done at ATA can be downloaded from the following datasets in Zenodo:
- Lucy recording with Allen Telescope Array on 2021-10-17: part 1/2, polarization X
- Lucy recording with Allen Telescope Array on 2021-10-17: part 1/2, polarization Y
- Lucy recording with Allen Telescope Array on 2021-10-17: part 2/2, polarization X
- Lucy recording with Allen Telescope Array on 2021-10-17: part 2/2, polarization Y
- Amateur radio
10ghz astronomy astrophotography ATA ccsds ce5 contests digital modes doppler dslwp dsp eshail2 fec freedv frequency gmat gnss gnuradio gomx hermeslite hf interferometry jt kits les lilacsat limesdr linrad microwaves mods moonbounce noise orbital dynamics outernet polarization radar radioastronomy radiosonde rf amplifiers satellites sdr signal generators tianwen vhf & uhf vlbi