Date: Thu, 21 Oct 2010 18:07:39 -0400
From: Patrick Allison <barawn@mps.ohio-state.edu>
Subject: Re: ARA DDA schematic

All:

So here's a graphic to help people out so they have a bit of reference
to work with. This is a kindasorta 3D model of the system, with the
DDAs, TDAs, ATRI board, and SBC (and the FPGA on the ATRI and the IRS
on the DDAs marked).

Presumedly the GPS board will mount on the ATRI as well, which will
just route its serial interface to the SBC via the daughterboard
connector - there's something like 4"x5" of real estate on the ATRI
available anyway, so, might as well. Dimensions of interest are
indicated (Amy, note: I bumped dimensions around a bit since I gave
you this copy): all of these dimensions were just chosen by me, and
not set.

So the DDA/TDA form factor is ~4.125" x 2.25", and the ATRI form
factor is 8.125" x 9.5" (this is ~half of 155 in^2: there's a board
vendor I know of that this makes it quite a bit cheaper for a
prototype run, although I'm not sure if it matters. The DDA form
factor in width (2.25") is set by a combination of 4x SMA edge-mount
connectors, and 4x 0.5" RF shields (on the TDA to protect the
amplifiers) - in length (4.125") it's set just by trying to cram the
connectors and the IRS on the same board. Then the ATRI's dimensions
are set by basically cramming 4 DDA/TDA-form factor cards beside each
other, and the SBC behind them.

Comments, please, on the form factor. It might be a good idea to pass
this around to the rest of the collaboration and see what they think.

I'm going to forward around a parts list (showing prices, etc.) in a moment.

Patrick