EQASCOM Pulseguide Monitor Tutorial

This document will attempt to explain how EQMOD plots Pulseguide events on the Pulseguide Monitor Screen and how to interpret these plots in order to maximimize the performance of your autoguiding/pulseguiding setup.

EQMOD receives ASCOM pulseguide command events from the controlling autoguiding software with two basic parameters;

* The direction of correction EAST, WEST, NORT, and SOUTH.

* and the duration of the correction (in milliseconds)

Refering to the screen shot of EQMOD's ASCOM Pulseguide Monitor (Figure 1), there you will see two graphs. The first graph is a plot of Pulseguide commands issued to EQMOD on the East and West side (RA Corrections). The second graph is plot area for pulseguide corrections for North and South side. (DEC Corrections)


FIGURE 1: Screen shot of EQMOD's ASCOM Pulseguide Monitor


Adjusting the Slider bars


FIGURE 2: Closeup Screen shot of EQMOD's ASCOM Pulseguide Monitor


Looking at the closeup screen shot (Figure 2), the vertical slider bars at the right side of the graphs allow the users to adjust  the plot's peak to peak display. It does not affect the actual guiding performance. The horizontal slider bars labeled as "RA Width Gain"  and "DEC Width Gain" adjusts the correction durations as issued by the autoguiding software in terms of percentage values. A 100% here means the duration values are processed as is without any changes. A 50% setting would mean half of the actual submitted correction duration.  At 50% RA Width gain for example, if EQMOD receives a pulseguide command at the East side with duration of 150 milliseconds, EQMOD will  execute an East wise correction with 75 milliseconds.


Interpreting the Pulseguide Monitor Graphs


As EQMOD receives a pulseguide command from the autoguiding software, a plot event is executed. All East wise correction commands are plotted (figure 3) at the top side of the first graph (1). West wise events are plotted at the lower part of the 1st graph (2). North wise correction are plotted on top part of the second graph (3) and southwise corrections are plotted on lower part of the second graph (4). The distance from graph center to the plotted curves is actually the duration data in milliseconds of each correction. This means a higher plot peak value equates a correction with a longer duration. This means that users should aim for plots at the center of the graph in order to conclude a good pulseguiding performance.  

FIGURE 3: Pulseguide Monitor Plot definitions


Different Plot possibilities and their respective interpretations


Figure 4 demonstrates different plot possibilites as labeled 1-8 and below is list on how to interpret them;

NOTE: Autoguiding Calibration should be done at 100% RA/DEC Width gain settings. Adjustments on the gain values should be done only during the actual autoguiding process and NOT before any calibration process.

FIGURE 4: Pulseguide Monitor Plot interpretations


  1. Pulseguide Oscillations on the RA side. It basically means that there are correction overshoots. To fix this, user has to lower the RA Width Gain settings. This has to be done right after an Autoguide Calibration process.
  2. Purely west side corrections. This means that there is a small amount of RA drift towards the east - may need to RA drift compensate
  3. Purely East side corrections. This also means an RA drift towards the west. - May need to RA drift compensate
  4. ZERO Duration corrections - MAXIMDL usually issues this kind of commands. It simply means a correction abort which is perfectly normal  
  5. Eastward drift correction. - In cases like this, multiple corrections are issued only on one direction with duration value getting smaller  at each correction instance. It means the duration value issued by the autoguiding software is very small. User may have to compensate by increasing RA Width Gain settings.
  6. Northside corrections - Succesive corrections on the North side would mean a DEC drift towards the south.
  7. Pulseguide Ocillations on the DEC side - Definitely a must to lower the DEC gain settings.
  8. Southward Drift Correction - Just like in #(5), user may need to increase the DEC width gain settings as the autoguiding application is issuing very small corrections.
#(2),(3),and (6) (single side corrections) should be ok as long as the fluctations are very small. Users even induce the drift to boost the performance of the autoguiding setup.