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Last updated: 19 April 2011
Subject:	Patch for Using ETX as a Panoramic Mount
Sent:	Monday, April 18, 2011 12:06:32
From:	richard seymour (
Here is the patch kit that will provide controlled pauses during a Landmark Survey.

It will require that you update to the current firmware (43Eg) as a part of the process.
The easiest way to do that is to download and install StarPatch  
Star Patch presents all of the optional patches as a tick-list.
(This one is labeled "ShortLandmark")
..but you can also use Meade's ASU updater for the process.

In the patch kit is a "ReadMe" file which explains (in the introduction)
how to fetch, modify and install the firmware.

Now for the patch:  I have "stolen" (well, "dual-purposed") the Focal
Length setting to serve as the pause interval control.
Focal Length is only used for two purposes in the normal code:
(1) as the basis of Utilities/Eyepiece Calculations
(2) to determine the size of the "Spiral Search" box that's invoked if
you tap GoTo a second time after arriving at a GoTo target.

You can restore the "normal" focal length at any time at the
Setup/Telescope/Focal Length  menu item, or by re-selecting your Telescope Model
(note: that "reselect" will revert the Train Drive results to their factory defaults).

Meade uses a 180,000-iteration loop as the delay during a Landmark Survey.
My 497 on my ETX90 showed that to pause about 4 minutes 15 seconds (255 seconds).
so we can quickly take ratios to yield:
180,000 = 255 seconds
18,000 = 25.5 seconds
1800 = 2.55 seconds
...or about 705 iterations per second
(due to Meade's wonky way of doing things, it's not an *exact* ratio, but it's close).

My ETX90's Focal Length is 1250, so that was about 2 seconds of pause.
I raised it to 2250, and the pause increased to a bit more that 3 seconds.
Due to the limits of the variable size in memory, you're limited to
32,255 as a maximum "Focal Length". (about 45 seconds)

have fun

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Copyright ©2011 Michael L. Weasner /
Submittals Copyright © 2011 by the Submitter