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Old 01-06-2012, 06:30 PM
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Tandum (Robin)
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Join Date: Apr 2008
Location: Wynnum West, Brisbane.
Posts: 4,161
Peter,
I have recently been looking at guiding via the sky controlled telescope driver as there was some chatter about guiding a paramount via ascom on the maxim forum. I got hold of the source code for the sky controlled telescope driver and found as you did that you need to tick some boxes to enable pulse guiding but the actual function in the driver to pulse guide simply adjusts the tracking rate of the mount. Some people found this method unreliable and instead of guiding via telescope in maxim, they are using the micro guide setting in maxim guiding settings and getting acceptable results. I don't see the difference as there is only one guiding function in the driver although micro guiding will send smaller corrections to the mount?

I then went looking for the sky direct guide functions mentioned in that thread and found them registered in the Windows COM sub system in my sky6 machine. This Sky function has only just been added to the skyx documents but it looks like it's been there all the time, undocumented. I believe the ascom driver guys will move guiding from the current adjusting of tracking rates to using this direct guide function to allow the sky to handle guiding movement instead of mucking around with tracking rates externally. I am surprised that Robert Denny didn't know of this function when he wrote the sky driver, after all he was one author of ACP Obs Control which is known to combine maxim, paramount and dome control. I mean I found it registered in windows without an issue?

As for the tpoint issue, maybe all these tracking speed changes are sending it bonkers but I don't see why there would be an issue using a guide cable from the camera, maybe up your exposure times so it sends less corrections.



Here is the guiding function from the sky controlled telescope driver if interested :-

Public Sub PulseGuide(ByVal Direction As GuideDirections, _
ByVal Duration As Long)

If Not m_bPulseGuide Then
Err.Raise SCODE_NOT_IMPLEMENTED, ERR_SOURCE, _
"Method PulseGuide()" & MSG_NOT_IMPLEMENTED
End If
' cdr try to implement pulseguide by using the SetTracking command
CheckConnected
If Duration > 10 Then
Dim RaRate As Double, DecRate As Double
RaRate = 0
DecRate = 0
Dim Rate As Double, dur As Long
' avoid short guide times by setting the guide time to 100 millisecs and reducing the rate
' try a maximum rate of 50% sidereal
If Duration < 100 Then
dur = 100
Rate = 0.075 * Duration
Else
dur = Duration
Rate = 7.5
End If
Select Case Direction
Case GuideDirections.guideNorth
DecRate = Rate ' in arc sec per sec
Case GuideDirections.guideSouth
DecRate = -Rate
Case GuideDirections.guideEast
RaRate = Rate ' in arc sec per sec
Case GuideDirections.guideWest
RaRate = -Rate
End Select
m_SkyTele.SetTracking 1, 0&, RaRate, DecRate
SleepEx dur, True
Select Case Direction
Case GuideDirections.guideNorth, GuideDirections.guideSouth
' set dec rate to 0
m_SkyTele.SetTracking 1, 0&, 0&, 0&
End Select
' resume tracking
m_SkyTele.SetTracking 1, 1&, 0&, 0&
End If

End Sub

Last edited by Tandum; 01-06-2012 at 07:29 PM.
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