5.3.10.2.3  TVC Value (Time Variable Compensation) 

This menu item helps compensate for the response delay caused by gear backlash when 

changing direction in Dec.  The TVC can eliminate the hysteresis that causes this to 

happen.  You can select a value between 0 and 255, which is the number of steps made at 

high speed whenever the Dec. direction is changed.  

 You should choose a "TVC Value" that results in a short or no delay when changing the 

guiding direction in Dec.  If you see a short jump, you have to decrease the value. 

5.3.10.2.4  PEC (Periodic Error Control) 

Train PEC

Clear Data*

PEC Off (On)*

Delay Correction*

Drift Correction*

Smooth Data*

Average Data*

Restore Data*

Periodic Error Control ("PEC") helps eliminate the periodic error caused by the very 

slight helical path variation in the shape of the RA worm.  You experience these as 

changes in the tracking speed, causing a star to periodically move a few arc seconds 

forward or backward while the worm gear turns.  The "period" is defined as the time of 

one worm revolution   about 4 minutes for the G 11, HGM 200 and MI 250, 5.33 

minutes for the HGM Titan, and about 8 minutes for the GM 8 and CI 700. 

As long as "PEC" isn 

t trained, the only submenu item that appears is "Train PEC."  You 

should only select this if you already having a star centered in the eyepiece reticle and are 

ready to train.  If you select "Train PEC," a counter on the display, begins counting down 

from 240 to 0 for the G 11/HGM 200/MI 250, from 320 to 0 for the HGM Titan, and 

from 480 to 0 for the GM 8 or CI 700. 

See Chapter 4, section 4.3 of this manual for a thorough explanation of PEC and for 

detailed instructions on how to use each one of the submenus. 

5.3.10.2.5  Mount Type 

Losmandy G 11

HGM 200/MI 250

Celestron CI700

Losmandy Titan

Losmandy Titan 50

Losmandy GM 8

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