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Old Jul 31, 2012, 02:36 PM
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Orlando, FL
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Did you know THIS about ***DJI NAZA?..***

I assume most of us are NOT aware of this issue since only few of us use 72 mhz systems these days. I am one of those that still use 72 mhz systems.
I put together an FPV platform recently. My radio is Futaba 9C 72mhz with a Futaba PCM Rx (149DP). I am using NAZA GPS as a controller. A few times, I realized that my failsafe got kicked in during normal flight at a very!.. close line of sight distance (like within 200 feet).
This prompted me to do a range check. That's when I realized I was in big trouble.
With the antenna down, radio failsafe was kicking in within 8 to 10 feet!.. Yes this is NOT a typo!.. 8 to 10 feet on a 72 mhz Futaba 9C system . Like a Joke!..
I thought my Rx was bad. I replaced it. Nothing changed. Then I thought my 9C Tx was bad; replaced that too; then I replaced the Rx crystal, Tx module and pretty much everything. Nothing helped!...
I was getting up to 10 feet range with antenna down and about 100 feet (LOS) with antenna fully extended.
This was unbelievable!.. and unacceptable!.. With these 72 mhz systems, I would get about 300 feet with antenna down (9C manual states only 100 feet) and with antenna extended at least 1000 feet or possibly more I never bothered checking after 1000 feet.
Well, the only thing left in my system that I did NOT change was the NAZA!..
I disconnected the NAZA and checked the alone Rx with a test servo and an external Rx battery and my range immediately went back up to 300 feet antenna down.
NAZA was interfering with 72 mhz system. How??? I was shocked.
I wanted to see what exactly was bothering 72mhz Rx. I started plugging in Naza wires one at a time and as soon as I made ONE SINGLE connection between Naza and 72 mhz Rx, the range was gone...
I did spend hours searching the internet about this issue, I found only one incident at Rcgroups forum. A guy was having an issue with his 72 mhz 9C and Naza. I pm'ed him and he said he did everything to solve this and finally had to switch over to 2.4 Ghz.

I am NOT trying to bash Naza or DJI here. I use their product but I also want to keep using my 72 mhz system. Now I don't know what to do.
Being in R/C for many decades, I do not have any explanation to how Naza would interfere with Rx system. Naza is NOT a transmitter nor it is a receiver.
If you have any knowledge/recommendation about this, I would like to hear from you.
I wish somebody would point out something I am overlooking and this issue would be resolved but I am not very optimistic about it...

Thanks
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Old Jul 31, 2012, 04:10 PM
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Well if your not optimistic about solving the problem switch to 2.4Ghz. The Turnigy9x with a FrSky modual is a very good, cheap solution.
You could try shielding your RX, maybe that will work. By the way, I have flown over 3 miles away with my 9c on 72MHz.
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Old Jul 31, 2012, 04:48 PM
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Originally Posted by Tarro View Post
Well if your not optimistic about solving the problem switch to 2.4Ghz. The Turnigy9x with a FrSky modual is a very good, cheap solution.
You could try shielding your RX, maybe that will work. By the way, I have flown over 3 miles away with my 9c on 72MHz.
Well if you already have a quality 72 mhz radio system (in fully working order) that you want to use, it doesn't make you feel good to spend extra money to switch to 2.4 GHz just because Naza mysteriously does not work with 72 MHz system.
It doesn't say anywhere in the Naza manual that this unit is designed to work with 2.4 GHz systems!..

I am open to the ideas of how to shield my Rx. With the included 2" jumper cables, I cannot separate the Rx from Naza much.

P.S. You got 3 miles with 9c on 72 MHz. Is that WITH NAZA hooked up to it???
9c isn't the problem here. The problem is when it is paired with the NAZA!..
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Old Jul 31, 2012, 05:51 PM
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VA
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Don't know anything about a Naza but if it is as you say you will probably need longer wires and they may need to be wrapped around ferrite donuts. They are the round rings that some servos and esc have their servo wires wrapped around. Usually way more rf interference is transmitted through a direct connection than an indirect one (air).
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Old Aug 01, 2012, 05:23 AM
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I agree, a ferrite over the connections from the RX to the Naza should solve the problem.

best regards Ferdinand
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Old Aug 01, 2012, 05:34 AM
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I've got a Naza laying around and a spektrum analyzer.
I'll put two and two together and see what kind of RF noise naza spews out.
I guess there's some harmonics from something that ends up drowning 72mhz band.
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Old Aug 01, 2012, 06:55 AM
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Orlando, FL
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Thanks guys!..

Filter/ferrite over the connections doesn't seem that will help in my opinion. I am not an expert but it feels like the RF interference is caused by direct connection rather than thru air.
I will use a longer jumper wire to separate the Naza and the Rx and see if the separation would make any difference. I didn't try this...

Also I will anxiously be waiting for timecops's test.
Welcome back timecop by the way. It is good to see you back here again...
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Old Aug 01, 2012, 07:01 AM
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That is the very reason for using the ferrite (direct connection), but of course you can also just wait what others will do for you.

best regards

Ferdinand
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Old Aug 01, 2012, 09:07 AM
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Orlando, FL
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Originally Posted by EndOfDays View Post
That is the very reason for using the ferrite (direct connection), but of course you can also just wait what others will do for you.

best regards

Ferdinand
Thanks Ferdinand. I am not ruling out anything. You might be right. As I said, I am not much familiar with filtering systems. I will do some read up on this soon...
If ferrite works, then I am thinking how to work it out as there are 8 male-to-male extension between the Rx and the Naza...

I will do some more tests while waiting for timecop's input...
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Old Aug 01, 2012, 09:59 AM
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Well dudes I setup the test and results aren't encouraging.
It spews out a TON of noise in low VHF.

DJI NAZA VHF RF GARBAGE SPEWAGE FAIL [72MHz] (0 min 53 sec)


Analyzer is centered at 72MHz with 60MHz span.
Camera ran out of SD card space at the end, but you get the idea.
ESCs/Motors/GPS doesn't emit anything on VHF. FC does. Oops.
Better upgrade to turnigy 9X and FrSky module.
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Old Aug 01, 2012, 10:38 AM
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Timecop, thanks for the quick reply. I wasn't expecting anything till tomorrow.

I see sadly that your test result confirms my claim. Naza messes up the 72mhz system.

In this case, do you know of anything(ferrite ring etc.) that would reduce the noise coming from the Naza FC?
If there is something cheap; worth to try, I would. Otherwise, I will think about other modulations. I may pick up a FrSky for my Futaba 9C for example...
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Old Aug 01, 2012, 10:50 AM
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I don't think shielding is gonna stop much here, i guess you can try getting your RX as far away as possible from the controller (maybe out on an arm or something) the noise is def there... its not the RC wires that emit it but the unit itself... So wrapping ferrite around RC signals isn't gonna do anything to it.
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Old Aug 01, 2012, 12:04 PM
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I got tired of chopping up antennas with my Gaui so I got the FrSky module and a few receivers for my 9CHP to use on my quads. They work good but also means I needed to change my video channel to 5.8 as 1.2 and 2.4 do not play well, even less well with the FrSky system. I prefer the smaller antennas (CP) on the helis anyway, and I just received my telemetry screen for the FrSky so I can keep an eye on my voltages etc. Takes me a second to swap out the Frsky with the 72Mhz tx if I'm flying my plane.
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Old Aug 01, 2012, 01:23 PM
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Heard good things about FrSky module. I will keep that as one of the options.

Before that I will move the Rx to one of the arms as much as the wires let me and see if I can gain some range by doing that.
Timecop since the source of the RF noise is the Naza FC, do you think that wrapping the FC with aluminum foil (or something similar) a few times would also help?
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Old Aug 01, 2012, 02:36 PM
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It is annoying when electronic devices interfere with other devices. If only there was a standard in place to ensure this wasn't allowed.
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