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Ali and Ben,
PHD2 pulse guiding direct from EQ mount to laptop requires Ascom based PHD2 compatible Goto , acquisition and or capture software like EQMOD , APT , SGP etc.... either direct EQ connect or wifi connect to mount and a separate USB cable from guide camera to laptop.
To install PHD2 including camera drivers , cameras , cabling and general information to get started , please refer to the latest PHD2 manual which comes with the software
Below are some general procedures and tips to assist with PHD2 guiding -
PHD2 Set Up and Guiding tips
1/ Try to Polar align to around 1arc minute error on Alt and Az
2/ “Auto select guide star” (recommended by PHD2) or manually select star that’s not too bright or saturated to avoid lost stars
3/ If guiding is poor ( above 2 arc seconds ) utilise the Guiding Assistant
4/ Check and adjust focus of your guide scope and camera to minimise lost stars
5/ Set your guide camera exposure time between 2 and 4 seconds ( Looping ) 2 seconds is a good starting point
6/ The SNR value of the guide star should be between 15.0 and 40.0 to avoid losing the guide star
7/ Don’t over correct settings , under correcting will let you manage your guiding performance better
8/ If Guiding is poor try and keep your min mo above 0.25 in RA and DEC . Don’t go above 0.6. A good starting point for min mo is 0.20 or 0.25
9/ Important- Build a Dark Frame library and a Bad pixel map to provide good calibration and stable guide star. PHD2 will only allow you to use one or the other
10/ The RA Osc value should be between 0.3 to 0.5
If it drops to 0.1 or lower then increase the RA aggressiveness or decrease the hysteresis
If it gets quite high say 0.8 then reduce the RA aggressiveness or increase the hysteresis
11/ Use Ascom Guiding - Laptop direct connect to mount ( preferred by PHD2 Developers) in lieu of ST4 connected guiding via camera to mount
12/ USB 2 cable to camera is not to exceed 5 metres
13/ Try and avoid cabling through a hub even a Powered hub, direct connect to the computer , you will have less issues
14/ Ensure you have the latest driver installed for your guide camera
15/ If guide camera is USB2 make sure you connect into a USB2 port with USB2 cable
If the guide camera is USB3 it most probably will connect with a USB2 cable
16/ Ensure you enter all the correct data for your guide camera into PHD2 brain tabs
17/ Make sure you get good Calibration. Calibrate within 10deg of celestial equator and within an hour of meridian
Once Calibrated save it and reuse it ( go to Brain in guiding tab and tick box “Auto restore Calibration”)
18/ if you lose guide star often , go to Brain in guiding tab and increase “Search region” and increase “ Star mass detection”
PHD2 Extra Guiding Tips
1/Try and keep your min mo in RA and Dec just above your arc sec error in both axis or leave as default (0.20) and see how the guiding performs over a few minutes
2/ Only make small adjustments in RA and Dec Aggressiveness. Wait for guiding to run for a few minutes to see any change or improvements
3/ If guiding is saw toothing in RA ( blue ) badly you maybe over correcting , reduce RA Aggressiveness and increase Min mo in RA only
4/ If guiding is saw toothing badly in DEC (red) then you could be over correcting, reduce DEC Aggressiveness and increase Min Mo in DEC
5/ If DEC ( red ) is staying for the most part above or below the centre line you are under correcting , so increase DEC Aggressiveness a bit and reduce Min mo
6/ If RA (blue) is receiving 2 or more consecutive pulses to correct it , then RA Aggressiveness is to low so increase by 5 at a time over a while to monitor its performance
7/ A random big spike in RA ( blue ) could be caused by many things like cable snag or drag , gust of wind , slight bump of the tripod , loose equipment or lost Guide Star
8/ A big random downward spike in DEC (red) can be caused by a “dither” command from your capture software through PHD2 , but you should see the word “dither” above the spike area on the PHD2 graph
9/ If guiding is still bad , go to the Brain and change the Guiding Algorithm from Hysterisis to “Predictive PEC”
It usually takes 20minutes of guiding on this algorithm to run 2 worm cycles of the mount and allow PEC training of the mounts performance. Sometimes the mount performs better using this PEC algorithm
10/ You can also try the Guiding Assistant which will make suggestions after letting the mount track after a test period of 2 minutes
11/ Only use the Backlash Compensation setting If Guiding Assistant advises to do so.
Go to Brain then Algorithms
Use only if your backlash value from the Guiding Assistant is 3 seconds or less or if the Guiding Assistance says to use this function
Advanced Functions for PHD2 - Predictive PEC ( Periodic Error Correction) in PHD2
PPEC is an alternative to the Hysteresis algorithm normally used for your mounts RA guide corrections and can provide improvements to your mounts overall guiding
Go to Brain
Select Algorithms
In ‘Right Ascension’ select “Predictive PEC”
Use all default settings for Predictive Weight, Reactive Weight and Min Move ( Period Length can be adjusted to suit your mounts worm cycle period but always leave “Auto Adjust Period” checked or ticked )
Do your normal Calibration then start guiding
PPEC takes time to train itself and perform
It starts out using the normal RA Hysteresis algorithm then shifts seamlessly to the PPEC algorithm after about 2 worm cycles of the mount when it learns the mounts performance
HEQ5 mount worm cycle period is 638 sec or 10 minutes 38 seconds
EQ6-R mount worm cycle period is about 480 sec or 8 minutes
PPEC will remain whilst guiding , stopping and starting guiding for focusing and dithering on the same target
If you stop and slew to a new target , PPEC must be turned off and then on again , start guiding and then re train itself again on the new target
Once training is complete after 2 worm cycles, the PPEC algorithm uses both reactive and predictive guide corrections which in principle is usually more accurate than just Hysteresis on its own
EQMOD has a feature to store your mounts PEC curve which is created by a third part software like PECprep and allows PHD2 to retain and use this data when running the PPEC algorithm. This saves PHD2 time when setting up and guiding for the next imaging session
The mounts Synscan handcontroller also has a function to record PEC and store it in the mount for PHD2 to use along side the PPEC function
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