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Topic: soloshot project, Auto-Filming yourself in motion while doing sports (Read 2 times) previous topic - next topic

PeterH


I don't think it uses GPS at all.  I believe it has to do with the timing or phase of 2 antennas.


There is an obvious antenna on the base unit which can only be used to communicate with the transponder. There is only one antenna and it looks like a non-directional antenna so I don't think there is any clever radio direction finding going on. This comment on the kickstarter page "Hey everyone- we designed SOLOSHOT with outdoor use in mind- the technology involved doesn't allow for indoor use." plus the fact you are recommended to be at least 50 meters away from the camera leave me certain that the system is based on GPS. I believe the transponder is essentially a GPS receiver plus radio transmitter and the base unit is a radio receiver, GPS receiver and compass.
I only provide help via the forum - please do not contact me for private consultancy.

sbright33

Great deduction Peter!  I believe you may be right.  I will build one.
If you fall... I'll be there for you!
-Floor

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sbright33

#12
Jan 12, 2013, 06:59 am Last Edit: Jan 12, 2013, 07:52 am by sbright33 Reason: 1
After learning more I can see there is only 1 GPS and no magnetic compass.
What if it could also do vertical tracking?  
Who would use it then?
Which sports?

His is not very accurate when <200m away.
What if I could make it work up close? 
Would this be valuable?

Off topic a little.  You might see where I'm going. 
How accurately could I measure distance apart by measuring the time of a radio signal?
The PPS pin of GPS has only 10ns jitter.  I figure I can measure about 30-300m distance precision with only a TX and RX.
Going one way that is, not round trip.

If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

PeterH

Are you sure there is no GPS or compass in the base unit? If not, I suppose it would be necessary for it to be given it's initial position by putting the transponder next to it and telling it to zero its position, and the operator would also need to tell it which way it was facing. I'd have thought a second GPS and compass would make it much more use friendly. However, maybe the cost would be prohibitive.

The radio direction finding based approach you're describing would potentially be a faster and more accurate solution, could be used indoors and would be better in many respects - but it would be *much* harder to get working IMO and would a lot of technological development. What Soloshot already does just needs a neat idea and some readily available technology brought together.
I only provide help via the forum - please do not contact me for private consultancy.

johnwasser


After learning more I can see there is only 1 GPS and no magnetic compass.

Where did you learn that?  I'd be surprised if there was not a GPS in the base station because the difference between two nearby GPS fixes will be much more stable than a new GPS fix and a previous GPS fix.


His is not very accurate when <200m away. What if I could make it work up close?  Would this be valuable?


Yes, short distance would be useful.  Indoor use would be useful.


How accurately could I measure distance apart by measuring the time of a radio signal?
The PPS pin of GPS has only 10ns jitter.  I figure I can measure about 30-300m distance precision with only a TX and RX. Going one way that is, not round trip.

Light travels about 1 foot per nanosecond.  With each end having 10-foot jitter I would think you would need a significant baseline (several meters) to triangulate a position.
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