Added Triple-D Bitrate Chart and Overview

[Abraxas3d]

Default Digital Downlink (Triple-D) chart and overview was added to the weekly report documentation.

[Abraxas3d]

The table is in bitrate order, but not in the order the modcods are laid out in the standard (Table 12, page 30, here https://www.etsi.org/deliver/etsi_en/302300_302399/302307/01.02.01_40/en_302307v010201o.pdf).

Kind of looks like the order they appear in the standard might be the way to send them. Plus, I didn't put in the 32APSK ones.

[MustBeArt]

I like the idea of sending them in performance order. Should be by Eb/N0 order or something. Maybe bit rate is a good proxy for that.

I suggest that in tables like this we should follow the lead of Table 12 in the spec and use “MODCOD” to refer to the numeric code, and “Mode” to refer to the description like “QPSK 1/4”. So, rename the MODCOD column to Mode and add a new MODCOD column with the numeric codes. (This would reveal that the table has some errors in it, including modes that are not in Table 12.)

This is also limited to DVB-S2 modes. Do we not want to include DVB-S2X at this point?

[MustBeArt]

Also, should include the assumptions behind the bitrate numbers: bandwidth 10 MHz, symbols rate 7407 kS/s, pilots on.

For our most immediate testing needs, we need pilots off, since pilots are not yet implemented.

Should probably also clarify whether the MPEG TS bit rates are only intended for short-term testing, or if ground stations are expected to implement TS reception as well as GSE.

Maybe this whole thing ought to be pulled out of the weekly report and put into a separate engineering document for technical review. Let the weekly report give the general description, but specifics and detailed tables need to be given more scrutiny than is usual for the weekly report.

[Abraxas3d]

OK - we also found that there are extra code rates in our code that are not in DVB-S2 specification.

QPSK has 11 code rates. In our code the same 11 code rates appear for 8PSK (should have 6), 16APSK (should have 6), and 32APSK (should have 5). So we should talk about removing the extra ones. It will reduce the switch case.

This would be a good time to add mechanism for pilots on or off too!

[Abraxas3d]

And, there are missing modcods in the project report.

I'll redo the project report with the modcods in performance order, with spec-compliant headers.

I think a separate issue/PR for the code would be the right way forward.

[Abraxas3d]

Done with correcting the chart.