[Ground-station] LDPC VHDL decoder review progress - need solid 5GHz RF prototype by late summer 2020

[Michelle Thompson]

-=-=-=-=-=-=-=-= LDPC VHDL =-=-=-=-=-=-=-=-=-=-

The LDPC VHDL decoder code review and video report is progressing fast.
Draft video report shared on Slack. Codebase on github is here:
https://github.com/aicodix/cnp

Huge thanks to Ahmet for the codebase and the explanations. Current focus
of Ahmet's work is the check node processor. Decoder organically growing
out from there!

-=-=-=-=-=-=-=-= 5GHz RF =-=-=-=-=-=-=-=-=-=-

After three or so attempts to get a good prototype 5GHz transmit chain, we
don't have one today. Skywave parts looked promising last year and we got
some results in the lab.

We need something that hooks up to something like the USRP x310 or
equivalent, and provides enough power to close the link up to GEO.

How much power is that? As much as we can get away with. Our link budgets
have numbers up to 10W on 5GHz.

Uplink signal is FDMA 4-ary minimum shift keying (modulation selected to
keep the RFs happy).

Forward error correction can obviously help. Re-using the work that we have
going on for the receiver (BCH and LDPC) makes the most sense.

Looking at the architecture and requirements for Gateway (LOP-G) LDPC
occurs over and over again. I'm in favor of selecting something that is
already specified in CCSDS/Gateway docs.

So, bottom line - we need a solid open-source RF transmit design by late
summer 2020.

We have *plenty* of funding to buy parts and PCBs. We need a solid design.
If you can help then step up and let's get this identified, designed,
documented, built, tested, and ordered.

We have 10MHz of uplink bandwidth to cover. We have channelization with 96
channels as the baseline 2020 demonstration. This is about 100kHz per
uplink channel.

Is there something off the shelf that can work? Is this something a student
can use for credit?

-Michelle W5NYV
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