Thread: Build Log A poor man's OSD
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Old Aug 22, 2011, 08:14 AM
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Once more I must write few words about GPS sattelite lock time .

GPS have long time for lock of satellites .
Usually the GPS problems are cause because of 5V (sometime12V) cameras jaming by step-up DC/DC converters .
Sometime by bad quality of supply voltage .
Sometime by Video TX (changing channel usually help) .
Sometime by metal pars near or under of GPS module somehow covering or suppressing signal (check if GPS looks at sky by proper side) .
Sometime by other equipment .

To obtain what happend the best is to connect only OSD and GPS directly to any monitor or TV at open space - then check satellites lock time . If still bad contact to me .
Then adding one by one rest of equipment (camera , video TX etc.) to see what is the jaming source .
Many confirmed cases of bad GPS work was because of cameras jaming - changing for other camera type solved problem.

About the backup battery for GPS - I made some experiments and when the whather is bad , battery is not helping a much in satellites obtain .
If condition are good - battery help - keep 6 sats after 5 seconds - but without battery GPS keep 7 sats within 50 seconds in the same good conditions .

Here is also very good tip for increasing GPS sensivity , this was checked by users with success on many platforms as quadro planes and others (even boat) .

We use alu tape or plate about 40x40mm , and place it under GPS module .
Alu plate is not grounded .
So , at platform where was a lot of jaming and glitches because of all electronic was packed in very small space as quadro , GPS hold only 4-5 sats after some minutes , what is a very bad result .
Now it detect at could start about 7-8 satelites within one minute (about 40-50 seconds) .
That means this modyfication rapidly improve GPS sansivity and suppress glitches.

Before mod :

After mod :

And add at plane
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Last edited by remzibi; Aug 27, 2011 at 07:27 AM.
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