Naza M v2 Satalite Problem

[BigPete]

Hello. I'm having a problem with my Naza loosing satalites with altitude. With take off I have 8-10 sats all the way up to about 25-30m. Above 25-30m I start loosing sats all the way down to zero sats. Happens every time. Decrease altitude, sats come back, increase, and they disappear. There is no obstructions. Only thing I can think of is the 900mhz vTx is interfering with gps, but doesn't make sense that the gps only goes out with higher altitude, and never with low altitude.

Any suggestions?

Setup:
DJI F550
Naza M v2
Spektrum dx9 2.4ghz
900mhz vTx 500mw /Rx
Fatshark base model goggles

 

[OneStopRC]

Did you try to fly without the 900 mHz VTX to see if that is causing the problem?... Also check your connections, maybe your vibration is increasing with wind resistance?.

 

[Motopreserve]

I've been hearing a lot about bad sat lock due to solar flares being intense lately. Not sure if this would change from ground to 30m???

 

[BigPete]

I moved the vtx antenna to a different location on the f550, farthest away from the gps puck. No change 25m and above, still loses all gps signal. All connections have been checked and are good quality. I unplugged the power to the vtx and that's it, zero problems at any height with gps signal. So if it's the 900 MHz vtx interfering with the gps why does it only cut out the gps signals above 25m? GPS below 25m has 8-10 sats 100percent of the time, likewise above 25m has zero sats at all times.

Anything I can do to my current setup? Still confused why the problem is altitude related.

Thanks for your guys replies.

 

[OneStopRC]

It has been said by a few, solar flares do not disturb satellite signals. To me radio is radio, I know the noise levels can be less on UHF bands and is not as susceptible to noise as is the HF bands. Not sure what your problem is, but I would test with no VTX and see if the same issue is there, just an elimination step.

 

[BigPete]

It has been said by a few, solar flares do not disturb satellite signals. To me radio is radio, I know the noise levels can be less on UHF bands and is not as susceptible to noise as is the HF bands. Not sure what your problem is, but I would test with no VTX and see if the same issue is there, just an elimination step.

Yes I tested with no VTX and the problem is gone. So it's the VTX. Just confused on why the problem is only above a certain altitude.

 

[OneStopRC]

Could be more noise from other systems that are covered when closer to the ground, I think you can put a filter on your GPS, Ferrite ring maybe? I am not 100% sure... Let me look into it and see what I can find.

 

[Motopreserve]

Big Pete, glad you narrowed it down. I'm sure you'll be able to figure it out with some trial and error. Have you tried copper tape? Not sure why it's altitude dependent - but it couldn't hurt.

OneStop: are you saying the flares cant effect the signal? I've read from Nasa that they predicted GPS/radio/ communication issues from the large flares that happened mid-June. Apparently we are in the throws of some intense 11 year cycle. That being said, the little flying I've done in the past month has not been hampered by lack of lock/signal.

 

[OneStopRC]

Here is your solution, which is not 100% fool proof. You will need to separate your GPS and VTX as much as possible. I have read it is hit and miss with your combination, I can only presume both frequencies have a close resonation, hence the interference. Mind you, 900mHz is very close to the 1.2gGhz Satellite Frequency.

http://www.rangevideo.com/en/rf-connectors/149-900mhz-13ghz-low-pass-filter.html

This is a Low Pass filter, you will put it on your VTX to cut down on the rouge emissions on the GPS frequency.

 

[OneStopRC]

Big Pete, glad you narrowed it down. I'm sure you'll be able to figure it out with some trial and error. Have you tried copper tape? Not sure why it's altitude dependent - but it couldn't hurt.

OneStop: are you saying the flares cant effect the signal? I've read from Nasa that they predicted GPS/radio/ communication issues from the large flares that happened mid-June. Apparently we are in the throws of some intense 11 year cycle. That being said, the little flying I've done in the past month has not been hampered by lack of lock/signal.

That is what I have heard.... Now remember, most of the Aviation systems use GPS. The GPS in your car also uses the same systems, whether is be in your car, in a fighter jet or on your RC Aircraft, we are all using satellites that use the same frequency 1.2 - 1.4 GHz and you don't see issues with them.

Radio systems are affected by solar activity, don't get me wrong. I am an amatuer radio operator and on certain bands we have to use during the day, some we use at night due to solar activity.

Anyway, here is an article back in may that was talking about the 11 year cycle you was referring too. Note the headline "Solar Flares May Interrupt GPS Navigation, Researcher Says"

http://www.utdallas.edu/news/2013/5...upt-GPS-Navigation-Research_article-wide.html

Also note the part about it may weaken the signal not knock it out, again this was back in may also..

The OPs problem is mainly from his 900 Mhz VTX bleeding all over his GPS frequency which we have already determined with an experiment by removing the 900 Mhz VTX.

 

[Motopreserve]

Thanks for the link. I saw the problem was unrelated - but I've been trying to determine the extent of the flares for my own peace of mind, so I figured I'd ask.

Ive seen the issues with the various freq interference. As you said - some people have great luck with just separation , others don't. I built a couple of those filters. They're cheap enough to buy pre-made, but if you want to put them on multiple craft it's cheaper (and damn easy) to make them yourself.

 

[OneStopRC]

Thanks for the link. I saw the problem was unrelated - but I've been trying to determine the extent of the flares for my own peace of mind, so I figured I'd ask.

Ive seen the issues with the various freq interference. As you said - some people have great luck with just separation , others don't. I built a couple of those filters. They're cheap enough to buy pre-made, but if you want to put them on multiple craft it's cheaper (and damn easy) to make them yourself.

Very true, and with a lot less weight in some cases...

 

[BigPete]

Thanks for all the great replies guys. I fixed the issue. So I bought my 900 MHz vtx used. It came with 4 different frequency Channels. It figured out it was actually set on 1040mhz from the other user. I tried each frequency channel and it looks like 910mhz worked the best. I'm guessing it because it's the farthest away from the gps frequency as someone else had stated. GPS locked on 100% of the time now. This forum is awesome. Thanks!

 

[OneStopRC]

Pete, be careful on the channel you use, I have read people saying in certain countries US and UK I think... That only 1 channel can be used, you are inside the 33cm Amatuer radio band and require a license to be there. Not only that, Ham radio are a secondary user on that band, primary users are government users, radar and so forth. If you interfere with operations someone might complain and come looking for your signal.

Just a heads up... 33cm band operates between 902.0 - 928.0 MHz... There is a pecking order, Primary (Government), Secondary (Amatuer Radio) and all others will accept interference from either of the Primary or Secondary. Which means if an Amatuer Radio is operating on this frequency around you, you could have your transmission stepped on and there is nothing you can do about it.

 

[BigPete]

Thanks for the heads up OneStop.