32000 count encoders installed

[sn1987a (Barry)]

I just got the new 32k encoder kit from Gary at Stellarcat this afternoon and installed them on my 18" Plettstone. Pretty quick and easy, did a rough fake daytime alignment on the Argo all seems to work. Will test out tonight.

[Steffen]

Wow! That's, what, 40.5 arc seconds per blip?

How fast can you move the scope before the signal overwhelms the Argo? I'm impressed the Argo Navis supports that high resolution encoders out of the box.

Cheers
Steffen.

[sn1987a (Barry)]

Well it's the usual, new toy so the weather gods sent thick cloud and intermittent rain. Will try again tonight. I did a quick goto after installation during the daytime and everything worked. Gary has been working on this for awhile now so I don't expect to have any issues.
Will post results as soon as weather starts to play the game.

[sn1987a (Barry)]

Managed to get a few hours of clearish sky the other night. New encoders definately made an improvement in goto accuracy and tracking. Tracking seemed to be much smoother with objects nailed into the EP center fov. I only setup with my 10mm Ethos and Paracorr II. Nothing fancy just the straight forward Alt Ref, 2 star align and then go.

I was slewing all over the sky and in most cases the goto object was a bullseye. Any slightly off center I would say were due to mount errors.

At one stage I did a goto to the Tarantula Nebula where it stopped dead center fov, cloud rolled in and I waited just over an hour before the sky cleared. When I looked again there it was still dead center.

NGC galaxys picked at random out of catalog, bam!. Planets Uranus, Neptune Jupiter easy. Jupiter especially made an impression. The seeing was poor but the tracking was so smooth that it was delightful to just stand perfectly still at the EP and finely adjust the focus and wait for monents of clarity. I can't wait to get these on the 28 and a night of clear seeing.

I didn't see any issues with overloading the Argo by going too fast although I will say I didn't try to.

I'll leave it to others to do the detailed analysis but for this numpty I was sufficiently impressed and delighted and I won't be going back to dumb 'ol 10k encoders

[sn1987a (Barry)]

Just installed 32k encoders on my LB16 this afternoon. Will be trying out tonight.

[Allan]

Nice work Barry. Hey, would you mind giving your Dob a quick push to the other side of the sky and reporting back with how the GOTO accuracy fairs after that. I would find that very useful, thanks.

[sn1987a (Barry)]

The Plettstone 18 works beautifully tracking and goto across the sky in my backyard. The LB 16 is not at the same level yet (although close) due to I think either mount errors or the settings I put in the servocat or both. Still nutting it out. Cloud and wind not helping.

[Allan]

So Barry, in your 18" the 32k encoders are keeping up with the telescope's position and not loosing their alignment even when you give it a fast manual push around the sky? Actually now I think about it, does the Argo have a similar dual encoder system that my Orion dob has, whereby I can manually move it to the area of the sky where the target is and then hit GOTO for the final alignment? I realise some systems have single encoders and if you bump them or manually move the telescope the system loses it's alignment.

[sn1987a (Barry)]

Sorry Allen I didn't actually try disengaging the servocat, pushing to the other side of the sky and then re engaging.

I did however target objects across the sky by straight goto's in my backyard and was honing in on greater and greater accuracy ( like setting the time correctly, it was about 10 minutes out doh! ) I'm close but I know it can be better.

I had it on grass slightly sloping I'll try a different position.

Too much cloud began rolling in so I went to bed will try again tonight.

You can see the two encoders the Argo uses in the pictures on the Alt bearing and in the center of the Az board under the scope.

I got this cheat sheet by Tim Hickman off the Yahoo Argonavis group site that I'll give a go.

SETUP MNT ERRORS
AQUIRE DATA
SAMPLE MODE = ON
DO 2 STAR ALIGN
MODE CATALOG
OR MODE TOUR
ENTER TO DESCRIPTION
DIAL SAMPLE MNT ERROR
SAMPLE 4 STARS
SETUP MNT ERRORS
DIAL COMPUTE
ENTER - USE NOW - ENTER

[Allan]

Thanks Barry, seems the new system is performing better than the old one for you, so that's encouraging. The GOTO accuracy sounds impressive.

[gary]

Hi Allan,

Originally Posted by Allan

So Barry, in your 18" the 32k encoders are keeping up with the telescope's position and not loosing their alignment even when you give it a fast manual push around the sky?

I think I can answer that. With 32,000 step encoders interfaced
to the Argo Navis, the maximum slew rate per axis is a hernia inducing 90 degrees a second.

Actually now I think about it, does the Argo have a similar dual encoder system that my Orion dob has, whereby I can manually move it to the area of the sky where the target is and then hit GOTO for the final alignment? I realise some systems have single encoders and if you bump them or manually move the telescope the system loses it's alignment.

When coupled with the ServoCAT GOTO/track system, there are four
encoders (two pairs) installed in all. The ServoCAT installation comes
with a pair of levers that you can flick to disengage the motors if you
so choose. You are then free to manually push the mount around and
Argo Navis and its associated pair of encoders keep track of the
scope's position. Re-engage the levers to re-engage the motors and
the system tracks as normal as if nothing happened.

The system uses servo motors rather than steppers. Though servo motors
are more expensive than stepper motors, they have distinct advantages
in telescope control applications because of their higher dynamic torque
range. The servo motors have their own optical encoders fitted to the motor
shafts which forms the servo feedback loop.

Argo Navis computes the object offset and tracking rates on behalf of
the ServoCAT. In the case of an Alt/Az mounts, the tracking rates are
continuously changing on both axes.

Before the year is out, Wildcard Innovations and StellarCAT will be releasing
new firmware for both the Argo Navis and ServoCAT.

This release includes the latest revision of the ServoCAT-Argo Navis protocol
which brings about some new features. For example, it is now possible
to track man-made satellites and other solar system objects at their inherent
tracking rates.

Watching a Dob track a fast moving satellite is an impressive sight.

The new SmartTrack feature allows the user to make small corrections with
the ServoCAT handpad to center a moving target in the eyepiece and the
Argo Navis and ServoCAT lock to that moving position.

We suspect owners will have queues of people waiting at sunset wanting
to have a go. I coined it teaching a Dob a new trick. It is pretty cool to see it in action.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[Allan]

Thanks Gary, that's a very comprehensive reply. I understand how it works now.