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Old Feb 12, 2012, 08:19 AM
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Originally Posted by Tracks View Post
Wrap the gps cable through a ferrite ring a few times. Also make sure the GPS cables are not crossing other cables. I was having horrible gps problems because the cable crossed over the throttle line from the ESC.
Indeed, my GPS cables are crossing other cable and the throttle line. But will this affect the GPS even if there is no current passing through the wires? Does your GPS problems occur when the GPS has set or has not set yet? The time I managed to get a lock was when there is only the GPS connected to the DOSD and powered up with a lipo, but I had to wait for two hours before I could get a lock on.
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Old Feb 12, 2012, 07:32 PM
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At the time, my DOSD was getting power from the current sensor, so I needed the ESC to be powered. This was one of the things causing me issues.

Once I moved the GPS away from the throttle cable, reception was fine. However, the GPS has to download an almanac. This can take an hour or so the first time you power it up. If you fly often and keep flying in the same location, then it shouldn't take more than a couple of minutes after that.

If you fly from distant locations... say an hour drive between sites, then it may have to reload the almanac. If you leave the GPS off for a long period of time, it may have to reload the almanac.

If it takes an hour or so everytime you power it up, but the GPS lock is good once it comes up, it may be that the battery in your GPS unit is dead. The batteries on my unit are replaceable, but on some units they are not.
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Old Feb 12, 2012, 08:29 PM
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Originally Posted by Tracks View Post
At the time, my DOSD was getting power from the current sensor, so I needed the ESC to be powered. This was one of the things causing me issues.

Once I moved the GPS away from the throttle cable, reception was fine. However, the GPS has to download an almanac. This can take an hour or so the first time you power it up. If you fly often and keep flying in the same location, then it shouldn't take more than a couple of minutes after that.

If you fly from distant locations... say an hour drive between sites, then it may have to reload the almanac. If you leave the GPS off for a long period of time, it may have to reload the almanac.

If it takes an hour or so everytime you power it up, but the GPS lock is good once it comes up, it may be that the battery in your GPS unit is dead. The batteries on my unit are replaceable, but on some units they are not.
I'm using the GPS that came with the DOSD. I tried again last night in an open space with just the DOSD powered up but have connected all the servo wire to the DOSD. Does this also affect the GPS fix? Just wondering, is it ok to mount the GPS at Ye side of the fuselage or under the wing?
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Old Feb 12, 2012, 08:32 PM
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Originally Posted by pyrojets View Post
I'm using the GPS that came with the DOSD. I tried again last night in an open space with just the DOSD powered up but have connected all the servo wire to the DOSD. Does this also affect the GPS fix? Just wondering, is it ok to mount the GPS at Ye side of the fuselage or under the wing?
The GPS needs to be facing towards the sky when mounted. It doesn't have to be on top of the plane though...as long as you don't have something (like carbon fiber) that might block the GPS signal from getting to the antenna.
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Old Feb 12, 2012, 10:53 PM
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The GPS needs to be facing towards the sky when mounted. It doesn't have to be on top of the plane though...as long as you don't have something (like carbon fiber) that might block the GPS signal from getting to the antenna.
By facing the sky, you mean it can be mounted on either side of the gps? Is it possible to mount the gps near a 1.2ghz video tx with a low pass filter? Is it ok to mount the gps between or near a carbon spar?
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Old Feb 12, 2012, 11:36 PM
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Originally Posted by pyrojets View Post
By facing the sky, you mean it can be mounted on either side of the gps? Is it possible to mount the gps near a 1.2ghz video tx with a low pass filter? Is it ok to mount the gps between or near a carbon spar?
There is one side of the gps that should face up. Even if you stick it on the underside of the wing, that side should still facing up. You should keep your gps as far from transmitters and other electronic devices as possible. But far is a relative term. I had mine 5 inches away from a 800mW Tx on my Floater Jet, and it worked fine.

Carbon fiber blocks radio signals. Try to keep the upward facing side of the gps clear of the carbon. I don't think mounting it on the top of the wing, over the carbon spar would be a problem, since the bottom doesn't really receive the signal.
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Old Feb 13, 2012, 12:19 AM
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Originally Posted by Tracks View Post
There is one side of the gps that should face up. Even if you stick it on the underside of the wing, that side should still facing up. You should keep your gps as far from transmitters and other electronic devices as possible. But far is a relative term. I had mine 5 inches away from a 800mW Tx on my Floater Jet, and it worked fine.

Carbon fiber blocks radio signals. Try to keep the upward facing side of the gps clear of the carbon. I don't think mounting it on the top of the wing, over the carbon spar would be a problem, since the bottom doesn't really receive the signal.
By mounting the gps at the underside of the wing, the signal may be affected by the carbon spar? Is it ok to run the gps cable parallel to the other wire such as servo wire, power cable and ESC cable?

Edit1: Found out that the place I tested the GPS was not "open spaced" enough (some wooden beam above it). Have switched to another place and the gps seems to be blinking after 6 mins. Though home has not set but I have a sat reading of 5. That is a good sign. Will see whether mounting at the wing will give better results. Just wondering, will the GPS be affected by the video TX though it has already locked onto a sat?

Edits2: Back to square one again. No flash on the gps and 0 sats. Plane and gps unit as it was before. One thing I did was to power up the video TX to check whether home has set. When has not set, I turned off my video TX and restarted my DOSD. From then onward, no light after 10mins, 20mins, 30mins and 40 mins. ( all these timings are individual test and not one test as a whole.) Have tried putting the gps unit at the wing. Will let you guys know of the result.
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Old Feb 13, 2012, 04:37 AM
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LC-Filter between Current Sensor and OSD board

I have a question, can I use this LC filter http://beta.ivc.no/lc_power_filter/ between the current sensor and the Dragon OSD board ?

The LC-Filter is limited to 1A can it be connected or does the OSD uses more Current ? How much current is the Dragon OSD using actually.
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Old Feb 13, 2012, 06:16 AM
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Have tried putting the gps unit at the wing. Will let you guys know of the result.
Can you post a picture of the gps placement, including cable?
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Old Feb 13, 2012, 08:29 AM
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Originally Posted by pyrojets View Post
The gps on the wing produces the same result as mounting it on the canopy.
It looks pretty good. The wiring is clean. What frequency and power is your video Tx? I would get a ferrite wring and wrap the GPS cable through it about 6 times.

(edit: "Wiring is clean" is a relative term in FPV )
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Old Feb 13, 2012, 11:28 AM
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mike thecrash. I have a little problem. How do i put the wires from my usb to my osd. can you display it on a picture
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Old Feb 13, 2012, 06:15 PM
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Originally Posted by Tracks View Post
It looks pretty good. The wiring is clean. What frequency and power is your video Tx? I would get a ferrite wring and wrap the GPS cable through it about 6 times.

(edit: "Wiring is clean" is a relative term in FPV )
Transmitting at 1280 Mhz at 800mW. Managed to coil the wire around the ferrite ring. Made an extension for the gps cable and when I powered up the DOSD the GPS started blinking in less than 5 mins. Not sure how long it took to set the home as my video was not plugged in but I can safely say that it should take less than 30 mins. Wanted to make sure that it is more or less working so I restarted the DOSD and the home was set almost immediately. Shall try it again tomorrow afternoon. Keeping my fingers crossed.
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Old Feb 14, 2012, 12:39 AM
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Originally Posted by MikeTheCrash View Post
First off I would double check that you have got the video in and out pins the right way around on the DOSD

after that, it may be that the VTx is out of design spec. The common fixes for this are a 100 Ohm resistor either in series with the video signal or linking the signal to ground, or even both.
Hi Mike

I checked all of my wiring again, all is as it should be, to the best of my knowledge, and the issue is still present

Quick non-techo question...
I went to Jaycar Electronics and they asked what wattage at 100 Ohm... I had no clue lol so I bought some 1W & some 0.5W resistors... which would be better to utilize?

Cheers folks!
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Old Feb 14, 2012, 02:16 AM
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Originally Posted by gazzzz View Post
mike thecrash. I have a little problem. How do i put the wires from my usb to my osd. can you display it on a picture
gnd>gnd
rx>tx
tx>rx
5v>power input



Quote:
Originally Posted by AussieHoppy View Post
Hi Mike

I checked all of my wiring again, all is as it should be, to the best of my knowledge, and the issue is still present

Quick non-techo question...
I went to Jaycar Electronics and they asked what wattage at 100 Ohm... I had no clue lol so I bought some 1W & some 0.5W resistors... which would be better to utilize?

Cheers folks!
I'm no electronics whizz but I'm thinking 0.5w would be plenty
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