Periodic error control

[Guest]

Just looking at periodic error control. Does it need to know the absolute position of the motor shaft in order to work? If so then how how does it know?

 

[andrew s]

You have to now where the motor is in its rotation. This could be an encoder or just a single position sensor. The information from these has to go to the software controlling the mount.

Regards Andrew 

[Guest]

Mine is an HEQ5. I'm pretty sure there's no encoder so I guess there must be a single position sensor.

Thanks

Steve

 

[andrew s]

13 minutes ago, woodblock said:

Mine is an HEQ5. I'm pretty sure there's no encoder so I guess there must be a single position sensor.

Thanks

Steve

 

That is very common it gives just gives a pulse per revolution. 

Regards Andrew 

[Guest]

I have an HEQ5 mount. As far as I know it doesn't have an encoder on the RA axis so for the purpose of PEC I assume that it must have some kind of index mark. I haven't tried PEC yet I'm just looking into it. So when you turn on the mount and want to turn on PEC the mount has to see the index mark before it knows where the motor shaft is. So I wondered if it does some kind of initialisation where it rotates the RA axis until it sees the mark before kicking off PEC.

[cletrac1922]

Find attached link for SynScan Controller

Go to page 42,and Periodic Error Checking (PEC) for EQ mounts

https://inter-static.skywatcher.com/downloads/Synscan_V4_Hand_Control_Manual_SSHCV4-F-161208V1-EN.pdf

John

 

  

[Guest]

Thanks John, I did read that before. It only says that it recommends you wait for at least one cycle before taking a photo.  I assume that is to ensure that it passes the index mark at least once. One book I have says that some mounts do a PEC initialisation when you turn it on.  I'm hoping to use the PEC built in to EQASCOM rather than the scope itself.

Steve