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Does this mount use Sitech controller software?


dan adi
 

Hello, I found this mount on mr. Dan Gray site https://www.youtube.com/watch?v=UfvRGd9OuWE
Is this the Astelco NTM 500 mount?
Does it use a Sitech controller? 


Don W
 

That video is a view of a prototype mount demonstrating the SiTech Brushless control system.  Conventional SiTech controllers all control brush type servo motors, which must use gears to move the mount axis using either worm/gear or friction drives.  These mounts are limited in speed to a handful of degrees/second motion.

The video you reference  uses direct- drive brush type motors - no gears.  Using direct drive and absolute encoders (65 million tics/rev) the mount can move at phenomenal speeds like 90 degrees/sec and be extremely accurate.  These are expensive mounts and controllers.  However they use the same software we use on our SiTech mounts - SiTechexe.exe.

I don't know the name of this mount.  Dan Gray has made several brushless direct drive mounts over the years.  His first years ago was an Alt-Az mount that would swing around and up and down like it was doing batting practice.  It looked dangerous.

Don W


Dan Gray
 

It used an early version of the ForceOne.  We re-used the existing encoders, but we had to add an interpolator to the sine/cosine signal from the encoders.
I can't remember the model number, but it is an Astelco.
Dan


On Sat, Feb 20, 2021 at 5:45 AM dan adi via groups.io <cioc.adriandan=yahoo.com@groups.io> wrote:
Hello, I found this mount on mr. Dan Gray site https://www.youtube.com/watch?v=UfvRGd9OuWE
Is this the Astelco NTM 500 mount?
Does it use a Sitech controller? 


dan adi
 

It looked identical to the NMT-500, so I thought I should ask. 
I think they still use the sitech controller from what I saw in a few youtube videos.
I looked around at these direct drive mounts, but the price is pretty high :) 
The Astelco is around 40K EUR. 
In sitech.exe I know there is the modeling option. After the model is made, does it affect (improve) only pointing? or does it also correct the tracking, thus enabling long unguided exposures? 
For example, I looked at direct drive mounts from ASA, and the software corrects errors in real time, like 100 times per second, thus enabling crazy long unguided exposures. 
Very interesting technology but pretty expensive for amateurs. A more reasonable approach is done by 10 micron, absolute encoders, but not direct drive.
Do you think there is a big difference between absolute encoders coupled with classic gears/worms vs absolute encoders and direct drive?
I am thinking that direct drive mounts can go along time with no servicing required ... 


Don W
 

Hi Dan A
Absolute encoders do a remarkable job virtually eliminating periodic error.  That is with direct drive mounts and with servo worm/gear mounts.  The key is that the absolute encoders are on the mount axis for RA and Dec or Alt/Az or Alt/Alt mounts.  A recent example of this is the AstroPhysics Mach2 mount.  All these mounts require alignment to Earth - Polar Alignment or perfect Latitude/Longitude.  Non-equatorial mounts also require very accurate encoders on the rotators used to compensate for rotating sky.  Dan uses an Alt-Alt mount able to track satellites from horizon to horizon - something a GEM can't do easily.

The only thing direct drives do that worm drives can't is high speed slewing.  They both can rely on axis absolute encoders - no PE, but require alignment to operate properly.

One note is that direct drive require excellent (perfect) balance.  When power is off, direct drive doesn't hold the axis, unless there is a powered brake - the mount will fall to the balance point.

Don W