Atmospheric Effects of Precipitation through Energetic X-Rays (AEPEX)

[git-addrian]

Introduction

Our team at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder (CU) is preparing for the launch and commissioning of AEPEX in the near-future (2025). We would like to add gr-satellites support for AEPEX telemetry.

LASP has previously created decoders for the following missions: CUTE, CTIM, CIRBE

AEPEX Mission

AEPEX is a 6U CubeSat that will study radiation belt losses through energetic particle precipitation (EPP) in the upper atmosphere, magnetopause shadowing, and wave-particle interactions. It uses a novel method to distinguish and quantify the impacts of these different components by measuring flux, spectrum, spatial scales, and temporal scales of EPP.

Spacecraft Radios

Band	UHF	S-Band
Type	SpaceQuest TRX-U	Clyde Space HSTX
Downlink Frequency	437.325 MHz	2405.0 MHz
Downlink Mode	GFSK	OQPSK
Downlink Baud	9.6 kbaud and 19.2kbaud	5 Mbaud and 10 Mbaud
Downlink Encoding	AX.25 -- G3RUH	CCSDS -- (Waiting on more details)
Uplink Frequency	437.325 MHz	None
Uplink Mode	GFSK	None
Uplink Baud	9.6 kbaud and 19.2kbaud	None
Uplink Encoding	AX.25 -- G3RUH	None

I have collected this information on the spacecraft radios. Please let me know if more info is needed!

Decoder

In the next few days I will submit a pull request for the decoder I have built for AEPEX, from this fork of gr-satellites.
For testing purposes, I have uploaded the file "aepex_beacons.bin" within "aepex_beacons.zip", which can be decoded with the aepex_70cm.py decoder.
aepex_beacons.zip

[K4KDR]

the file "aepex_beacons.bin" within "aepex_beacons.zip", which can be decoded with the aepex_70cm.py decoder.

Sorry to bother, but I've tried as many methods as I can think of but only get errors when I try this. Could I trouble you for the syntax or process that one would use to decode that sample file with your python decoder?

Many thanks!

[daniestevez]

Thank you for opening a discussion for AEPEX!

I've taken a quick look at lasp@9e098d7 and this is the kind of thing that is needed to support the 70cm telemetry in gr-satellites: a SatYAML file and the telemetry definitions using construct. When the code is ready, send it as a pull request for review.

For the S-band radio, more information would be needed to support it, since CCSDS has many variants (some of which are already supported in gr-satellites). If you get more details, share them here. Also, an IQ recording would help.

[git-addrian]

Hey Daniel,
I have a pull request ready for you: #675

For the S-band radio, more information would be needed to support it, since CCSDS has many variants (some of which are already supported in gr-satellites). If you get more details, share them here. Also, an IQ recording would help.

For now, it is likely that AEPEX will only be able to provide a 70cm decoder (similar to CUTE, CTIM, and CIRBE). As I track down more details on our specific variant of CCSDS, I can share them.
I can also see if I can find an IQ recording to supplement the binary file.

[daniestevez]

If you have details or recordings about the S-band downlink, please share them. Implementing a decoder for this is something that I might do.

[K4KDR]

Thank you both for all the work to get another LASP satellite into gr-satellites!

I fed the provided .BIN sample data file into a GNU Radio flowgraph using the newly added support for AEPEX...

... and the output frame matches the source:

... I'll attach the telemetry decoder output here if you would like to review it to confirm that Amateur end-users such a myself are processing your data correctly!

aepex_decoder_k4kdr.txt

[git-addrian]

Hi @K4KDR,

Nice! This exactly matches my output. Thank you for running that through a flowgraph.