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INDI Library v1.9.5 Released (08 Mar 2022)

Bi-monthly INDI Library released with new drivers and bug fixes.

Polaris Hour Angle & GPSD

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Hello

I have a just setup an USB GPS module for my Pi4.
GPSD is working and VirtualGPS is disabled.

Do you know why "Polaris Hour Angle" is different between Ekos panel and INDI panel?
And which one should I use?


Thanks
Nico
Last edit: 1 year 10 months ago by Nicolas MONNEINS.
1 year 10 months ago #56153
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Hello,

Location is in multiple places within AstroBerry. A quick check is to open GPSPANEL. The default location is Warsaw, Poland. If that is your location, then the clock of the PI has drifted. The PI does not come with an RTC. RPI cases are not RTC friendly. Look at PI time. Adding an RTC is doable with planning.

If GPSD is working, INDI Device Manager should accept GPSD when selected to do so. If not selected or not working, INDI takes the System.

This leaves us with the multiple places of location. KSTARS and PI have a GEOGRAPHICAL LOCATION. In PI and KSTARS, the default location is Warsaw, Poland. Change both locations to your geographical area. Then look at Polaris angle.

Synchronization of location is a manual effort. KSTARS is dependent on the OS for many time and location stores. INDI logs will show the clock difference between its time and the system.

It is an aesthetics issue. I like harmony. So, I normalized my AstroBerry. It should make smaller log sizes.
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1 year 10 months ago #56161

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Thanks.
"GPSPANEL" and "INDI-KSTARS-EKOS" both give my current location, retrieved from my GPS module, so I think that my GPS module & GPSD are working properly.

But I still don't understand why the "Polaris Hour Angle" is different between Ekos panel and INDI panel? There is more than 20minutes difference.

However, the HA value given by the left GPSPANEL seems closer to the correct one (the one I get with SynscanInit).
1 year 10 months ago #56166

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Replied by Andrew on topic Polaris Hour Angle & GPSD

I have seen this before. Often different polar finder apps calculate a different PHA. Without understanding what they are doing under the hood I can only guess as to why. But I've always suspected some do not factor in the Time Zone Meridian offset correctly.

Edit: Here are the results from various tools.
GPSD 2:03
KStars 1:37
SynscanInit 1:46
Stellarium: 1:37
Cartes Du Ciel 1:38
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
The following user(s) said Thank You: Nicolas MONNEINS
Last edit: 1 year 10 months ago by Andrew.
1 year 10 months ago #56167

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Hello,

The big take away from this is that each solution says to believe their story on where they think we are. In the meantime, our scope and its location are tied to a system. Each system must sync the mount to its internal clock. Therefore the polar pole has a million differences depending on where each system calculates its PHA.

The true test comes when the first GOTO and SYNC command goes to M81 and you see nothing by space. What is interesting is that KSTARS, Stellirium, and Cartes Du Ciel have very similar solutions. 1 sec difference is insignificant. No mention was given of syncronized clocks in these findings. The other are significantly different. Who does everyone believe?

I just recently added RTC to my RPI4B and RPI3B+. GPSD was nice but Raspbian and NTP don't mix. As proof, my RPI4B clock time was 1 hour behind the GPSD time in EKOS. I was puzzled. Then I remember the Raspbian and PI caviat about no RTC. Ok, the geographical location profile needs to be changed. Yes, I am not in Warsaw Poland.
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Last edit: 1 year 10 months ago by John Robison. Reason: syntax
1 year 10 months ago #56172

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Replied by Andrew on topic Polaris Hour Angle & GPSD


I had each application open at once with common location and time settings. Then quickly noted their figures to within the minute.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
Last edit: 1 year 10 months ago by Andrew.
1 year 10 months ago #56180

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Hello,

Fantastic. Then the difference between is pretty significant. GPDSD +29 secs and SynscanInit +9 seconds is pretty big swag calculations.
1 year 10 months ago #56182

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Replied by Andrew on topic Polaris Hour Angle & GPSD

It's worse than you think. The smallest significant figure I provided was Minutes, not Seconds.
GPSD 2:03:ss
KStars 1:37:ss
SynscanInit 1:46:ss
Stellarium: 1:37:ss
Cartes Du Ciel 1:38:ss

Also I live at Longitude 75°W, just a few kilometers from the Eastern Time Zone Meridian. So Time Zone offset is not a factor at play here.
INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Waveshare Stepper Motor Board - DIY Focuser
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
1 year 10 months ago #56186

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Hello,

Thank you for the correction. Minute deviations are pretty dramatic. Even in minutes, KSTARS, Stellarim, and Cartes Du Ceil are more aligned than GPSD and Synscaninit. NTPD GPSD is supposed to not be working with Raspbian INDI. No hooks are in the process. This would explain its drift faster. Then again, NTPD requires configuration. That would make it a guess.

It should not matter the location of Polaris in one sense. We are looking at establishing the Celestial Pole. After that, time becomes critical. If not, deep space is all the view we will get. If we wait 8 minutes, the object will be in the view eventually.
1 year 10 months ago #56226

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Note that GPSD calculates Polaris Hour Angle for the time of last fix (the clock does not tick after), whereas sliding GPS Panel provides ticking clock synchronized with GPS (or system if you use Virtual GPS).
As the result Polaris Hour Angle displayed in sliding GPS Panel is current (and constantly changing), which is not the case for GPSD.
--
Radek Kaczorek
Astroberry Server | Orion CT8 | Askar FRA 400 | NEQ6 (hypermod) | Atik 460EX | ASI 1600 | ASI 120MM | Atik EFW2
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1 year 9 months ago #57762

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Replied by Joaquin on topic Polaris Hour Angle & GPSD

“RPI cases are not RTC friendly”
Which problems they have ?
Stellarmate gadget comes with a RTC...
Celestron AVX
Celestron SCT 8” Edge HD, Primaluce ESATTO
TS Optics Photoline 80mm f/6 FPL53 Triplet-Apo, Primaluce SESTO SENSO 2
Celestron OAG, Lodestar X2 guide
Pegasus PowerBox Advanced
Stellarmate Gadget
AstroPhotography Tool (APT)
Nikon D90
1 year 9 months ago #57802

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Hello,

Cases with heatsinks and fans around the big chip IC. Usually the RTC wants Pins 1,3,5, and 7 for the 3V device needs. This is where the conflict happens.
1 year 9 months ago #57810

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