LRIS-R red mosaic

This web page reiterates the comments from the file in CVS at

Notes about the nomenclature and conventions used with the LRIS-R upgrade, the CCD mosaic in the dewar, pre-amplifier, and CCD controller.

The current draft of the nomenclature for the LRIS-R focal plane is visible on the web here:
This defines CCD locations 1 and 2.
This defines amplifier locations 1, 2, 3, 4.

Mounted astride the LRIS-R dewar is the preamp enclosure which houses the preamp board. The preamp board identifies its 4 signal paths as
1A, 1B, 2A, 2B.
The design of the dewar internals and the hermetic seal to the preamp board do not permit permutation of the video signals between the amplifiers on the CCDs and the inputs to the preamp board.

In the CCD controller there are 2 video boards.
A jumper on each video board indicates to the software whether it is board 0 or board 1.

On each video board there are two video connectors.
When the CCD controller is oriented with the cooling plate on top, then video connector A is above video connector B.
Another way of saying this is that A is top and B is bottom.

Using the nomenclature on our drawing of the LRIS-R focal plane the only way that the CCDs can be connected to the preamp is

The wiring from the preamp board to the CCD controller can be permuted.
In fact, there are three different segments to each of these wires.

There is one internal segment from the video connector on the preamp board inside the preamp enclosure to the external connector of the preamp enclosure; these are easy to permute.
There is one external segment from the external connector of the preamp enclosure to the external connector of the CCD controller; these are part of a fixed cable bundle and cannot easily be permuted.
There is one internal segment from the external connector of the CCD controller to the connector on the video card inside the controller; these are easy to permute.

The permutable cables are basically anonymous, and there is little advantage to identifying all three parts. The only relevant aspect is the overall connection between preamp and controller video board.

The conventional wiring from preamp board to CCD controller is thus:

In the CCD controller the software maps from the CCD controller board signal connectors to the "Video Inputs" identified in the mosaic data structure. This has been consistent during LRIS-R development and is unlikely to change.
The conventional mapping is as follows:

By following the above mappings all the way through we produce the following wiring mapping which is the one which will be true for the conventional permutation of wires from the LRIS-R preamp to the LRIS-R CCD controller.

Steve Allen <>
Initial deployment 2009-04-15
$Date: 2010/04/16 21:41:28 $