St4 or pulse?

[boabsta]

Just wondering what would be best for guiding with. I have a HEQ5pro and a QHY5v to guide it.

Am I better to plug the QHY into the st4 port on the mount or have it pulse guided through eqmod?

Rab.

[Stephen]

Not aware of any significant differences, but I prefer pulse as it's one less cable

[Spikey]

and I prefer ST4 as it's one less setting

[boabsta]

lol I think it shall just have to be a case of suck it and see then.

[Stephen]

and I prefer ST4 as it's one less setting

Go on then, you're going to have to explain that one to me?

[Spikey]

Go on then, you're going to have to explain that one to me?

The ASCOM pulse guide settings, I don't have to play with them - just the Autoguider port rate, which to be honest I've never changed

[boabsta]

Ascom pulse guide settings? Sounds like something I need to know?

[Stephen]

The ASCOM pulse guide settings, I don't have to play with them - just the Autoguider port rate, which to be honest I've never changed

I think the two are directly comparable? The only setting I've ever changed is a slider (think this is the pulse guide setting you are referring to) and I just whack it up to 0.9X and leave it there. Calibrates fine and off it trots

Then again I have got lucky with guiding, never had to change any settings really for anything (brain icon in PHD, though I'm on Maxim now) it's all just worked for me. I know others struggle with getting the settings right though

[steppenwolf]

I use both on my EQ6 (sometimes the pulse guiding doesn't work unless I re-boot the PC so I just change to ST4 as by then, I have acquired my object!!). I can see no difference in tracking ability with one caveat - if you also run PEC via EQMod, PEC and pulse guiding work in harmony whereas PEC and ST4 will fight one another.

[boabsta]

Thanks Steve, never knew that. I would imagine it would make sense to run pec with the guidescope. Shall give that a bash next clear night.

[Daniel-K]

whats pulse guiding?

[ollypenrice]

I've had so much hassle with ASCOM that I'd walk from here to Birmingham to avoid it, so it's ST4 for me.

Olly

[Stephen]

whats pulse guiding?

Rather than sending the corrective signal down the ST4 cable, software can send the corrective signal down the EQMod cable instead.

[Daniel-K]

Rather than sending the corrective signal down the ST4 cable, software can send the corrective signal down the EQMod cable instead.

so i dont need an st4?

[Stephen]

so i dont need an st4?

If you use pulse guiding, correct

[Pete Presland]

another vote for pulse guiding, i had nothing but troiuble trying to use the ST4 cable. EQMOD cable,ASCOM & PHD software and its been fairly trouble free since

[robbieince]

if you are already controlling the scope via laptop - then pulseguide is one less extra cable. If you aren't - lets say you are using a handset and just using the laptop to capture images and process guide images, then the st4 is the only option.

[kirkster501]

Rather than sending the corrective signal down the ST4 cable, software can send the corrective signal down the EQMod cable instead.

Speaking in the context of WITHOUT guiding......

This is interesting. It implies that the continuous movement of the mount is solely down to commands continually being fed to it by the PC. But I find that is not the situation since if I disconnect the serial lead from the PC the mount carries on tracking regardless. This would imply that ASCOM/EQmod just tells the mount "slew here and get on with it" - no further instructions are sent and if the mount wanders then that's tough.

WITH GUIDING ?????? I take it the whole idea of guiding is that continual commands *are* constantly sent to the mount via the serial lead in pulse guiding?

Sorry, I am not sure whether i am asking a question or making a statement - seeking clarification me thinks !

Rgds, Steve

[Stephen]

Speaking in the context of WITHOUT guiding......

This is interesting. It implies that the continuous movement of the mount is solely down to commands continually being fed to it by the PC. But I find that is not the situation since if I disconnect the serial lead from the PC the mount carries on tracking regardless. This would imply that ASCOM/EQmod just tells the mount "slew here and get on with it" - no further instructions are sent and if the mount wanders then that's tough.

WITH GUIDING ?????? I take it the whole idea of guiding is that continual commands *are* constantly sent to the mount via the serial lead in pulse guiding?

Sorry, I am not sure whether i am asking a question or making a statement - seeking clarification me thinks !

Rgds, Steve

I'm not sure either LOL

My statement says nothing about tracking, it's only referring to guiding as that was the question at hand

Guiding is sending a correctly signal (move left a bit, move up a bit) based on observations made on an image by software.

Given that you can change the tracking rate in EQMod (sidereal, lunar, solar) I would propose that the initial command to track is sent to the mount from the handset/software and then the mount continues until software tells it otherwise

[chrisshillito]

Speaking in the context of WITHOUT guiding......

This is interesting. It implies that the continuous movement of the mount is solely down to commands continually being fed to it by the PC. But I find that is not the situation since if I disconnect the serial lead from the PC the mount carries on tracking regardless. This would imply that ASCOM/EQmod just tells the mount "slew here and get on with it" - no further instructions are sent and if the mount wanders then that's tough.

WITH GUIDING ?????? I take it the whole idea of guiding is that continual commands *are* constantly sent to the mount via the serial lead in pulse guiding?

Sorry, I am not sure whether i am asking a question or making a statement - seeking clarification me thinks !

Rgds, Steve

The mount is semi-intelligent. It knows how to driver stepper motors but knows very little about astronomy or astronomical calculations. So essentially what EQMOD can tell the mount to do is:

• Move a motor a number of steps in a given direction
  
• Set the mount moving a given rate/direction
  

When EQMOD tells the mount to track it does so using the latter command. The mount, if left alone, will then just keep moving at the specified rate. If the mount has been correctly polar aligned then there is no reason why it should ever wander off - the electronics and serial protocol are all optimally designed for initiating and maintaining sidereal rate (but other rates are less accurate). That said there is a roughly periodic wobble (it isn't actually repeatable over any sensible time frame) due to the nature of the mechanics.

A guiding pulse simply consists of sending two rate change commands, one to move the mount at the guide rate and one to return to sidereal. The autoguider software specifies the interval between the commands and EQMOD does the rest. EQMOD's PEC also works on a similar approach with the tracking rate be regularly adjusted to counter the periodic error movement (and any pulse guide movements will be additive to the PEC correction).

ST-4 guiding is exactly the same in principle except the rate changes are commanded via a hardware interface on the mount itself. EQMOD is unaware of ST-4 guiding and so cannot arbitrate between it and PEC as a result ST-4 pulses are likely to trash any currently active PE compensation so the value of PEC+ST-4 may be questionable.

Chris.