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Last updated: 31 October 2002
| Last updated: 31 October 2002 |
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PERFORMANCE ENHANCEMENT - CREATING THE PERFECT "GO TO" ETX OR LX 90
PART 2 - AutoStar Downloads and Post-Download Initialization
Thus far, in this performance enhancement guide, we have discussed the critical need to have of an optimum MECHANICAL operating system for the computerized ETX or LX 90 telescope to function properly with the AutoStar GO TO. Without a responsive, tight, and non-slipping telescope, all the computer firmware and programming knowledge in the cosmos will not help you slew from one object to the next.
Before proceeding to optimize your telescope through these "performance enhancement reports" make sure that your telescope has been thoroughly checked for all mechanical pitfalls that can be detrimental to the scopes performance and to your enjoyment of this hobby.
As mentioned previously, our problems with the ETX or LX 90 are a complication COMBINATION of: mechanical problems and glitches that can be fixed (Part 1); downloading and post-downloading improper initialization procedures (discussed here); and, user error, including alignment, calibration, training and leveling the telescope for perfect performance.
What - just two weeks ago - seemed like increasingly growing problems with the design and function of the Meade AutoStar today appears as if the problems ARE indeed surmountable and in most cases, easy to remedy if the steps in this three-part enhancement report are followed.
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DOWNLOADING AND UPLOADING SOFTWARE/FIRMWARE -
I will be the last to pretend that my downloads of new AutoStar data and versions from Meade have been anything but fun and easy; had it not been for the help of fellow-ETX-ers Dick Seymour and Mike Weasner and others on the ETX web site, I still would not understand the errors of my ways.
The purpose of this series is to instruct you on ways to overcome the problems that we have all experienced in the past and tweak your telescope to perform as it was designed (and CAN) do. If you don't believe that such miracles happen, merely go back and read my test report on the night when all of my modifications, adjustments and inputs were finally corrected and/or added to the telescope/AutoStar combination!
I will leave the downloads and data editing to the computer experts among us, as I certainly am not among them. What I want to convey is the process AFTER you have edited you libraries or new ephemerides into the latest version of AutoStar that you have uploaded from the Meade web site.
IT IS IN THIS PROCESS FOLLOWING AUTOSTAR UPLOAD that we have been introducing what appears to be conflicting information to the AutoStar, and thus may be a possible culprit in such things as the "rubber band," improper tracking, random slews, and much difficulty in GO TO and alignment. Time will tell, but by following a simple procedure and adding ONE MORE SEQUENCE to your POST-DOWNLOAD commands to AutoStar, I believe that your ETX or LX 90 will suddenly become the "buffed" telescope it is supposed to be.
It is suggested (although NOT necessary with the new Meade Autostar Upload program v3.61) - after upgrading to any new version of Firmware - that you consider a full RESET to your AutoStar AFTER the first initialization is finished (this would be the initialization that AUTOMATICALLY COMMENCES after "Download Complete/Initializing AutoStar").
Following is the sequence which I have discovered allows considerably better communications between AutoStar and the ETX/LX90. I do not pretend to know WHY or HOW it works; I merely know that it DOES WORK, as will be seen in my carefully-controlled testing parameters. But first, let's review the SEQUENCE as I believe it SHOULD PROGRESS:
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POST-UPLOADING SEQUENCE FOR AUTOSTAR AND TELESCOPE -
This by far is one of the most important, combined with proper mechanical behavior, aspects of getting your ETX / LX90 and AutoStar to perform properly. We are set in our ways for sure, and usually unless we are TOLD to do something through instructional information we typically WILL NOT do a logical step, or often - as in this case - not think it important.
I stumbled across what may be the major factor in many computer flaws that users are reporting quite by accident: when my initialization sequence began AFTER "downloading complete" I NEVER HEARD my motors being calibrated. That - when AutoStar is "Reset" as it should be after every download - is one of the first processes that should take place with initialization.
This section addresses TWO new avenues that are open to you to improve your telescope's computer performance: 1) the post-firmware/software upload initialization process that you MUST follow AFTER upgrading your AutoStar, and, 2) adjustments of the NEW MEADE "Altitude Percent" and "Azimuth Percent" values AFTER MOTOR TRAINING that are available on Autostar to remove backlash as well as improve RESPONSE TIME when using the "slow" and "fine" rates of your arrow keys. This, as you will see, is a MAJOR contribution toward getting your AutoStar to GO TO as well as track more efficiently.
POST-UPGRADE READYING SEQUENCE -
It is exciting to download new data from the Meade web pages that you expect to improve the accuracy and enjoyment of your telescope; at the present time Meade has done an excellent job of providing faster and more simple methods of data-sharing with the ETX and LX 90 users than before. It is not the purpose of this document to discuss downloading from the Meade site, nor uploading into your AutoStar.
What WILL be discussed are the many steps after that familiar "Download Complete" message appears on your PC (or MAC) once the AutoStar has sucked all the information from your files.
Notice that IMMEDIATELY after "Download Complete" your AutoStar shows the initialization sequence, usually hung up on repeating 1) the sun warning until you tell it to go away. From there, you go to 2) the instruction page, next to 3) the date and 4) local time and on to 5) "Daylight Savings?" and off to 6) "Afghanistan" probably, then to towns in your state or province, and finally to 7) to "Telescope Type."
NOTE: on versions other than 2.1ek, the initialization process includes as the first step (before sun warning) your selection for language; at the present time, there is no prompt for this as the v21.ek is English only. Once your selection of language is made, "testing motors" appears and there is slight movement (calibration) in both altitude and azimuth axes.
Once all those parameters have been entered, you TURN OFF the telescope power, disconnect the cables from the AutoStar and telescope, turn off power to your computer and disconnect cables from its port and you are ready to go outside and align....right? WRONG.
HERE IS THE POST-DOWNLOAD COMPLETE SEQUENCE THAT YOU SHOULD FOLLOW TO ASSURE OPTIMUM COMPUTER CONTROL OF THE ETX / LX 90 TELESCOPES:
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PRE-MOTOR TRAINING INITIALIZATION SEQUENCE -
Now you have (hopefully) downloaded your new information into AutoStar, disconnected everything and are ready to go out for an evenings observing to "test the new stuff." In the past, such evenings have been major disappointments to many observers with new idiosyncrasies popping up all over the place: "rubber banding," random slewing, poor tracking, horrible alignment....
Remember that your AutoStar has already "initialized itself" immediately following its last download. BUT IT DID NOT RESET ITSELF...that is something you must do to REMOVE the previous data on motor training recognition. It "appears" that your last motor training is not erased like other data (your name, site location, telescope type, etc.); indeed, the conflicts between locating objects with AutoStar suggests that a data recognition problem exists in its memory, likely caused by two conflicting drive motor training sequences of which the AutoStar must reckon with the best it can.
With the newest updater from Meade (ASU 3.61) it is NOT necessary to always RESET the telescope after a new version of firmware is uploaded; only if you think you are having problems with communication, data recongition or motor failures do you need to reset. The Autostar will now retain all user data that is stored - if you wish. This includes your 1) training; 2) calibration; 3) locations (sites); 4) ephemeris objects (suchs as tours, comets, etc.); and 5) personal (owner) data.
SO....here are additional steps that you might consider taking PRIOR to training your motors outdoors (if you RESET!), and of course PRIOR to aligning for the night's use. Some of these appear repetitive but are necessary because you are CLEARING OUT your entered data from AutoStar to give it a fresh start after installing the new versions of firmware. Forget the fact that an initialization has already taken place.....you are about to do ANOTHER ONE!
Once you have finished this last series of preparatory steps, you are getting close - but not there yet - to actually TRAINING THE MOTORS (Part 3) and aligning your telescope for operation.
There is ONE MORE NEW - and very important and helpful - process that you must do prior to training the motor drives of your ETX or LX 90.
SETTING YOUR ALTITUDE AND AZIMUTH BACKLASH PERCENTAGES -
New on the latest AutoStar uploading tool (A2.4 and beyond with 2.1ek and above firmware) is a wonderful addition that eliminates sloppy tracking, problems with reaction time using the fine tracking arrows, creeping after slewing, sidereal oscillations and general gear train backlash.
Backlash is simply the residual time necessary for the gear train (the gear teeth in particular) to "catch up" and reverse any motion; if you have been "going left" and suddenly wish to reverse and "go right" it takes some time to for the gears to "catch up with each other" to the point where torque is finally once again applied to the actual drive gear (Part 1). When using the very slow arrow keys with AutoStar, sometimes there is no motion whatsoever because of the great time necessary to turn the combination of so many gears. Hence, a lot of users have told me that they never even "used 1 or 2....because nothing happened!"
Believe me, if you follow all of these enhancement techniques, you will be able to effectively use "1" and "2" from now on - with little or no hesitation BEFORE and no residual creep AFTER you press the button!
Every Meade telescope is different and each has its own distinctive combinations of RA and DEC backlash. For example, my RA backlash was horrible when I first got the telescope; taking the base apart and cleaning, adjusting the clutch and drive system (Part 1) greatly helped reduce the backlash....but did not get rid of it altogether.
Conversely, my DEC axis had no backlash at all, even though it had mechanical "play" in its components.
So, mechanically, I have my telescope as good as it can be without going into custom drives and supercharged custom overhauls. But it still had tracking problems and it still suffered with backlash in RA. Just in the nick of time, a warrior arrives on a white stallion with....and AutoStar IMPROVEMENT, the Alt and Az percent adjustment function!
Here's how to get yours started.
1) Make an INITIAL SETTING prior to "Train Motors" (Part 3) on either or both axis percentages. Like me, if one (or neither - you would be blessed if that was the case) axis appears to NOT have backlash problems and drifting problems, just leave the two functions alone. We envy you.
2) Both Altitude Percent and Azimuth Percent are found on your AutoStar keypad (with A2.4 and above with v2.1ek and later firmware) under "SETUP/TELESCOPE/MOUNT...." then scroll down until you get to the two categories. DO NOT CONFUSE WITH "AZIMUTH RATIO" and "ALTITUDE RATIO" as these are factory presets for the engineering specs of the motor system and NEVER should be changed. In my opinion, the ability to change these options should not even be accessible to the user. Altitude Percent and Azimuth Percent are found AFTER the ratio categories.
3) When either appears on the lower line of the AutoStar readout, press "Enter" to bring to the top and open; both are factory present in the firmware at 01%; allowing for no restriction on backlash whatsoever. Meade suggests that, if you are having a backlash slop problem to "start with 50% and work your way DOWNWARD") back to "0" percent. I don't recommend this for two very clear reasons:
a. at 50% the motion of pressing the arrow key(s) would be very jerky, with the telescope drive suddenly surging ahead and then slowing to the normal rate ( 1-9 ) you have selected. The 50% actually is a speed surge of 50% faster for the first 0.3 seconds (roughly) than the rate selected to compensate for delays of backlash to allow the gears to engage much quicker. Once the backlash is removed by this surge, the rate of the slewing/tracking reduces to the normal rate selected.
b. you should have the backlash setting at a REASONABLE percent for correction for your scope PRIOR to "Train Motors" so that training will take the backlash percentage into account when "marrying" the AutoStar to the telescope drives.
Thus, I will toss out this suggestion that has worked perfectly for me. If you are having backlash and/or lagging problems in BOTH DEC and RA, even if it seems severe, try a setting of 15% for each axis (each must be set separately on the AutoStar). This should do the trick; I have found that even 20% is too high and unpredictable and above that is not usable. IF, on the other hand your ETX or LX 90 is like most of ours, your primary lag and response time/backlash troubles are in the RA/Azimuth axis ONLY. If so, then don't even bother the DEC/Altitude setting, merely set the Azimuth Percentage function to 15%. I think that value will cover nearly all ETX's out there; as far as the LX 90, its "newness" prevents any estimation but I would guess, based on the drive gear size over the ETX that the percent should be LESS, say 10% on either or both axes.
Once your percent has been keyed in, press "Enter" and it remains until you once again "Reset" the Autostar! Now you are ready to TRAIN THE MOTORS and ALIGN you scope precisely for the "Perfect GO TO Experience!" REMEMBER!! be sure to ALWAYS train your motors with the telescope in the configuration (i.e., Polar or Alt-Az) that it is going to be used in....and ALWAYS set that configuration (under "SETUP/TELESCOPE/MOUNT...." to whichever you are using BEFORE training the drives! This is another pitfall that some users have fallen prey to that results in less-than-perfect performance!
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APPENDIX - The Test Parameters for AutoStar
Figure 2-c, following demonstrates the three variable parameters in evaluating my conclusions regarding AutoStar accuracy, the need for "Reset" function after downloading, the resulting performance increase by changing the backlash parameters, and finally, the decision that changing the backlash percents should be made PRIOR to "Train Motors."
I use two Autostars, one for actual operation at the scope and the other to download new data and AutoStar versions. Also, the second unit has been invaluable at helping unravel what must be done electronically to make the computerized Meade telescope perform electronically like they were designed.
"AutoStar #1" is the actual used AutoStar and you can see that it has been loaded with everything pertinent that has been discussed so far; it is the one that provides the incredible results demonstrated in Part 1. "AutoStar #2" for this test was similarly downloaded as can be seen, but had NOT been reset nor had the Azimuth/Altitude percentages been updated; "AutoStar #3" is merely Autostar #2 AFTER resetting it and programming in all the parameters that made "AutoStar #1" function as good as it does. The complete variables and parameters are listed below each one.
My conclusions are based on these "three" AutoStars and the variables, from the following results:
1) All three contained the latest A2.4 updater and v21.ek firmware, loaded on the same date off the same computer, etc. With the parameters shown for "AutoStar #1", tracking was near-perfect; the GO To (described in detail in Part 1) speaks for itself, and all delays seem to be eliminated; response is immediate and there is no residual "overcorrection" at any slew/center speed. In essence, this combination on my ETX 125 gave near-perfect performance in every respect, far better than I had EVER experience with the ETX or LX telescopes. Setting the "Azimuth Percent" (no need for the "Altitude") took out virtually EVERY BIT OF BACKLASH that my mechanical adjustments could not! Alignment was quick and accurate, even in Polar mode.
2) Everything in "AutoStar #2" is identical, EXCEPT the unit was NOT "reset" after the first initialization immediately following downloading of A2.4 with v2.1ek. Nor were either parameter changed for Azimuth or Altitude Percent. The results were identical to what everyone is experiencing: creep-after-beep; wild slews to alignment stars, imperfect GO TO's, sidereal tracking problems and significant rubber-banding in alt-azimuth mode. Perhaps the biggest problem was the ineffective "slow" and "fine" settings for centering (#'s "1" and "2" on the keypad) with bothersome waits to actualize and then residual travel after the object was centered; this was eliminated with the settings in AutoStar #1. It took three alignments on one night and two inaccurate ones on the next night to make a satisfactory start to observing with this setup.
This comparison was done ON THE SAME TELESCOPE! Only the AutoStar information was different; both A.S. handboxes were trained with the ETX 125 as well, so only the variables could be a source of change.
3) THEN, I took AutoStar #2 and "turned it into" Autostar #3 by redoing the "Reset", then a new initialization, then added the percent parameters and subsequently "trained the motors" after all had been reset and done. The results? "AutoStar 3" on the night of February 17 2001 performed 1-on-1 with AutoStar #1 with the identical and newly-loaded parameters that AutoStar 1 had all along. This merely proves that it is: A) not the telescope, since the same ETX 125 was used for all tests; and B) not the AutoStar, since "AutoStar #2" failed miserably, but when REPROGRAMMED to the configuration of AutoStar #1 (thus becoming my imaginary "AutoStar #3), it performed brilliantly!
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Okay, now we have seen the advantages of providing the best mechanical atmosphere possible for our ETX or LX 90 scopes, and also the importance of the crucial sequence necessary for a "clean" upload after new firmware/software is installed. We have seen that a "reset" might be the easiest way of fixing all your errors even though none of the literature or manuals suggest it should be done.
[end part 2]
P. Clay Sherrod
Arkansas Sky Observatory
Conway / Petit Jean Mountain
Arkansas
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