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Apr 11, 2009, 09:21 AM
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blackstork osd gps problem


As I“ve lost both helicopter and sailplanes when flying FPV by not finding my way home (
FPV adventure with RC heli T-Rex 600 (2 min 25 sec)
) I bought the Blackstork OSD with GPS. I now have two of them but none is working. Can“t get the GPS to work. It just says “starting GPS“ and keeps counting upward. Does anybody have a clue. Are there other GPS modules that would work better? Best regards Claes.
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Apr 11, 2009, 10:36 AM
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Capy-Norway's Avatar
wait 2-4 minutes before start flying. that helps for me.
Apr 11, 2009, 10:54 AM
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Quote:
Originally Posted by dukenuke
As I“ve lost both helicopter and sailplanes when flying FPV by not finding my way home (http://www.youtube.com/watch?v=Un5gNj2oBC8) I bought the Blackstork OSD with GPS. I now have two of them but none is working. Can“t get the GPS to work. It just says “starting GPS“ and keeps counting upward. Does anybody have a clue. Are there other GPS modules that would work better? Best regards Claes.

I've also bought a blackstork osd in last november, and it was not working, so i've decided to unsolder the microchip microprocessor on it and solder my own ATMEGA168, and now i'm building my own osd....because there was no way to make the blackstork osd work.
Apr 11, 2009, 01:48 PM
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I also have a blackstork osd and it also keeps counting.
I have tried to wait up to 5 minutes and never got it to work.

/lasse
Apr 11, 2009, 11:48 PM
Yeah Baby
bignose13's Avatar
Read my reply in this thread
https://www.rcgroups.com/forums/show...3#post12006889

also read my thread here about the problems I'm having, good luck if you get this working
https://www.rcgroups.com/forums/show....php?t=1020252
Last edited by bignose13; Apr 12, 2009 at 12:09 AM.
Apr 12, 2009, 04:44 AM
Registered User
Hi,

I solved this problem with a small electric wire directly plugged into an existing hole of locosys board just secured with hot glue.
Since this mod, I get fix in less than 45s at ALL times.

Apr 12, 2009, 06:23 AM
Registered User
That is very strange mod for GPS I ever seen.
Do you have backup battery or it still connected to BS with just 3 wires?

Quote:
Originally Posted by bandito66
Hi,

I solved this problem with a small electric wire directly plugged into an existing hole of locosys board just secured with hot glue.
Since this mod, I get fix in less than 45s at ALL times.
Apr 12, 2009, 03:06 PM
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Everything is stock except this mod.
Apr 18, 2009, 02:18 PM
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mmormota's Avatar
A backup battery is a must (I soldered in a CR2032 button cell). Both the gps modul and the CR2032 is fixed on the back of the OSD using double sided tape and heatshrink.
I had to wait long minutes before, now it's ready in a few seconds. Actually it's working for the time I put back the plane's battery cover and look into the goggles.
Last edited by mmormota; Apr 18, 2009 at 02:26 PM.
Apr 18, 2009, 03:43 PM
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Quote:
Originally Posted by mmormota
A backup battery is a must (I soldered in a CR2032 button cell). Both the gps modul and the CR2032 is fixed on the back of the OSD using double sided tape and heatshrink.
I had to wait long minutes before, now it's ready in a few seconds. Actually it's working for the time I put back the plane's battery cover and look into the goggles.
can u explain how the battery helps??
I had a similar prob with the blackstork i bought a couple of months ago, no sats. with GPS for over 5 minutes..I sent the GPS back and replaced with new one and now i get sats. within 25 seconds!
Apr 18, 2009, 04:11 PM
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mmormota's Avatar
Quote:
Originally Posted by hovaboy
can u explain how the battery helps??
I had a similar prob with the blackstork i bought a couple of months ago, no sats. with GPS for over 5 minutes..I sent the GPS back and replaced with new one and now i get sats. within 25 seconds!
It can't help if the GPS is not working at all.

But helps a lot, if the gps is working, but the startup is very slow, sometimes takes as much as 15 minutes.

The GPS unit needs a correction database file (so called "almanac") to calculate the accurate position. Each GPS moon periodically sends it, but capturing it needs time. If there is no backup battery, the GPS unit has to wait until almanac downloading from a moon.
If there is a backup battery, the GPS unit keeps the almanac (captured in a previous mission) in memory and doesn't has to wait for a new one, starts almost immediately. Of course it replaces the almanac as soon as a newer version arrives.
Apr 18, 2009, 04:24 PM
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Quote:
Originally Posted by mmormota
It can't help if the GPS is not working at all.

But helps a lot, if the gps is working, but the startup is very slow, sometimes takes as much as 15 minutes.

The GPS unit needs a correction database file (so called "almanac") to calculate the accurate position. Each GPS moon periodically sends it, but capturing it needs time. If there is no backup battery, the GPS unit has to wait until almanac downloading from a moon.
If there is a backup battery, the GPS unit keeps the almanac (captured in a previous mission) in memory and doesn't has to wait for a new one, starts almost immediately. Of course it replaces the almanac as soon as a newer version arrives.
gocha ya! interesting info....thanks
so am I right to assume that the battery would help the GPS in flight as well...for instance when the aircraft makes hard banking turns it will help recovery time to the lost sat. signals?
Apr 18, 2009, 06:29 PM
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mmormota's Avatar
Quote:
Originally Posted by hovaboy
gocha ya! interesting info....thanks
so am I right to assume that the battery would help the GPS in flight as well...for instance when the aircraft makes hard banking turns it will help recovery time to the lost sat. signals?
No, it can't help then. During flight the unit has power supply and keeps the almanac in memory anyway. The backup battery only helps to keep the data when the video battery removed after flight.

I suspect - but not sure - that there was a hmmm... not so good series of GPS modules, that's why some people has problems whyle others are satisfied.
I had some problems with my first GPS module, then it killed in action (crashed), I ordered a replacement GPS modul, and this one seems much better.

If the satellites often lost during flight, there are the following possible reasons:

1. The GPS module is not good enough (either the chip or the built-in antenna).
A better, more sensitive GPS modul, or external, higher gain antenna could help.

2. The video transmitter disturbs the GPS module, makes it less sensitive.

2/a
because the GPS module input is sensitive to the frequency of the video, the GPS modul is not selective enough.
Higher distance to the transmitter, ferrite beads on the wiring or (if nothing else) a better GPS modul could help.

2/b
because the video transmitter radiates out-of-band harmonics even at 1576MHZ, the frequency of the GPS transmission.
A filter (1576MHz notch filter, or low pass filter in case of 900MHz Tx) could help on the video Tx output, or higher distance, ferrite etc.

A simple test to check if the problem is the video Tx or not: connect the video output of the osd to the goggles. Turn off the video Tx, and check how many satellites are in range. (do it outside of course) Bank the plane, check if the sats are still there.
If there are less then 6-7 satellites, or too much satellites lost on 45 degre banks, the problem is the GPS modul itself. A modern, sensitive modul has to work properly even at 90 degree bank.

Then test it again, but now through the video Tx. (re-connect the Tx, connect the goggles to the Rx as in normal flight) If much less sats received this way, the problem is 2/a or 2/b.
Last edited by mmormota; Apr 18, 2009 at 06:36 PM.
Apr 19, 2009, 01:41 AM
Registered User
I wonder how this issue has been solved in the GPS unit used by Remzibi OSD, which had no complaints so far...
After the initial fix, of 4-5 minutes, it starts decently fast, under one minute.
The GPS size is smaller than BS unit, I doubt there is any battery inside but I may be wrong.
May 13, 2009, 03:19 PM
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Thread OP

New GPS module


I will try soldering a small battery for the GPS. It also sounds interesting with alternative GPS module for the OSD as mmormota wrote. What was it called and where did you buy it? /Claes


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