Accurate sensors for push-to with Skeye

[Mokusatsu (Australia)]

I had an LG Gpad tablet which did a HORRIBLE job of push-to using Skeye. The GPS and sensors just didn't have the precision necessary to get me even looking in the right general direction and this was not much improved by careful calibration and using all the precautions advised like getting rid of magnetic objects, turning the tablet through that figure of eight to force the sensors to recalibrate etc.

My Samsung S3 phone did a somewhat better job, but wasn't anything much to write home about.

I am now on the market for a new tablet, ideally a small 8" one. I'm thinking of a Samsung Galaxy Tab S 8.3.

Has anyone who has used this model tablet got any feedback on the accuracy and precision of its onboard compass, GPS, etc for the purposes of using it as a push-to DSC with Skeye?

[bojan]

Built in compass is usually a problem here.
You must use it away enough from any metallic/magnetic objects.

[Mokusatsu (Australia)]

Sure, though my Samsung S3 phone, my 3rd gen iPad and my LG Gpad all had internal compasses, the Samsung and iPad were in general agreement about the direction of North, the LG was a definite outlier and pointed in a different direction.

I can conclude that my LG's internal compass was particularly rubbish.

My next tablet which I am considering to replace the LG once the warranty credit comes through may be a Samsung Galaxy Tab S 8.4. Has anyone used one of these for Skeye and can they report on the performance as a DSC?

The LG suffered significant drift and jitter. It just wasn't up to it, but other users of Skeye report that it can be good enough to get you within a low magnification eyepiece of your desired object. I want to know what tablets these happy users are working with!

[bojan]

Originally Posted by Mokusatsu

.....that it can be good enough to get you within a low magnification eyepiece of your desired object. I want to know what tablets these happy users are working with!

I very much doubt that. No compass is that accurate (~0.5°)

[Mokusatsu (Australia)]

Supposedly the software uses a fusion of several sensors in addition to the compass, and Skeye makes it easy to recalibrate by pointing your scope at celestial landmarks near your object and fixing onto them, meaning you can use it for high-tech star hopping.

It's therefore not entirely about the absolute accuracy of the compass, more the precision and stability, combined with other sensors like accellerometers.

These sensors in the LG apparently were worse than the ones in my iPad and Galaxy S3 phone.

[ZeroID (Brent)]

My 7" Samsung Tablet has GPS and seems to be pretty accurate when pointed at the sky with a live sky app. Does good with satellite finding as well
Compass is still rubbish but inclinometer is pretty good for dec settings as long as you are careful with a flat surface.

[julianh72 (Julian)]

Originally Posted by bojan

I very much doubt that. No compass is that accurate (~0.5°)

It's not just using the compass sensors, it's also using the accelerometers and gyroscopes. The accelerometers give a very good resolution on inclination, and the gyroscopes are very sensitive at detecting rotations. The clever thing is that the app doesn't require tremendously high absolute resolution, it works on detecting changes. You periodically align it with a star or planet in the area of the sky where you're viewing, then if you move the OTA, the sensors detect a change in Altitude and Azimuth to determine your current target.

It works extremely well for me. (Nexus 4 and Nexus 7 2013.)

By the way, the app recently received an update to be able to use remote sensors on a couple of Bluetooth LE sensor devices, which will allow you to use your phone or tablet handheld, coupled with a small "dongle" strapped to your scope. I'm waiting for them to write the code for the TI SensorTag with I already own, and I'll report back when I have the chance to test it.

[Meru (Michael)]

If the compass is the weak link, maybe try using a dedicated, accurate electronic compass? Even perhaps a digital tilt meter. One with a digital readout to get you in the right area

[bojan]

Originally Posted by Meru

If the compass is the weak link, maybe try using a dedicated, accurate electronic compass? Even perhaps a digital tilt meter. One with a digital readout to get you in the right area

Or just encoders.. coupled with CdC or Stellarium