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Sep 20, 2010, 07:44 AM
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On the topic of the KPC VSN505PHB, here's a few spectrum analyzer plots showing the radiated RFI from this camera. It indeed is pretty noisy, covering the entire 433MHz ISM band and then some. One marker is dead on the center of the 433MHz band at 432MHz. With -79dBm the transmitted RF power is just 12.6pW (that's pico indeed), so here the same recipe applies, space the camera and the UHF Rx antennas as far apart as possible.



Fig 1. Baseline plot, KPC VSN505PHB camera turned off.



Fig 2. Plot with the KPC VSN505PHB camera turned on.



Fig 3. Center band marker at 432MHz at -79dBm, 12.6pW.

So, would I recommend this camera for flying long range with a UHF RC control system? No, I wouldn't, however this camera can be made a lot less noisy with some extra measures. Would I recommend this camera for general FPV flying on non-UHF RC control, most certainly!

In the end it all comes down to intended use, so please keep that in mind.

Cheers,

Sander.
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Sep 20, 2010, 07:46 AM
FPV Desert Beta Test Center
No need to tiptoe around the 505 problem with UHF. If your bought UHF it wasn't to fly around the airport. You are after long range and the 505 is now known to be a bad choice for that purpose. Being a UHF manufacture you don't need to be told that and the attempted group buy is forgiven since the problem wasn't apparent at that time.
Sep 20, 2010, 07:53 AM
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Quote:
Originally Posted by Gary Evans
No need to tiptoe around the 505 problem with UHF. If your bought UHF it wasn't to fly around the airport. You are after long range and the 505 is now known to be a bad choice for that purpose. Being a UHF manufacture you don't need to be told that and the attempted group buy is forgiven since the problem wasn't apparent at that time.
I'm not, don't for one minute think I ever would tiptoe around an issue. Rest assured that if there's an issue I would be the first one to own up to it.

However you seem to be operating under the assumption that folks buy a UHF control system just for long range flying. Most of our customers seem to not be interested in that, but are mostly interested in rock solid reliability of their RC control and having the peace of mind that they'll run out of video range long before RC control becomes an issue.

If you take a moment to browse through some of the configurations listed on these forums you'll realize most folks don't even fly a plane capable of >10km flights, hence long range might be of interest to some, but not to all of them.

So, I'm sorry, but I don't agree with you, UHF isn't solely used for long range flying. And as I have pointed out above (please take a moment to read my replies fully as I take great care in wording them so they address the issue at hand and do not raise more questions) I don't think the KPC VSN505PHB is suitable for long range flying indeed.

Cheers,

Sander.
Sep 20, 2010, 08:07 AM
FPV Desert Beta Test Center
Quote:
Originally Posted by ssassen
I don't think the KPC VSN505PHB is suitable for long range flying indeed.

Cheers,

Sander.
Agreed!
Sep 20, 2010, 08:41 AM
KJ6BFN
henkvdw's Avatar
Good information there. Thanks Sander.
Envy you guys with the cool equipment to do these measurements.
What is considered to be long range flying?
Long range to some will be flying further than their Standard 2.4 GHz , 35 MHz, 72 MHz etc. system will allow.
Others would define it as upwards of 10 km. And some in between and some more.
Matter of definition too.
Sep 20, 2010, 08:55 AM
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Quote:
Originally Posted by henkvdw
Matter of definition too.
Certainly, but the aim is to get maximum range, in that case reducing all unwanted RFI in a setup is paramount.

Cheers,

Sander.
Sep 20, 2010, 09:07 AM
On a holiday?
boopidoo's Avatar
Yeah, thanks for these tests Sander, they are very interesting. If it's possible and you feel like you have the time it would be interesting to see results from the popular Turnigy Plush ESCs, some BECs and the very common HK SS ESC. I don't know if you have these but if you do it would be interesting.
Sep 20, 2010, 09:13 AM
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Quote:
Originally Posted by boopidoo
Yeah, thanks for these tests Sander, they are very interesting. If it's possible and you feel like you have the time it would be interesting to see results from the popular Turnigy Plush ESCs, some BECs and the very common HK SS ESC. I don't know if you have these but if you do it would be interesting.
Oh, I can answer that for you. From HK the Turnigy Plush 10A, 25A and 30A are excellent, as is the Turnigy Plush 40A with 3A switching BEC. The Plush 60A and 80A also have a switching BEC but that's considerably more noisy.

The SS I never tried as I find the Plush series offers great bang for the buck so to speak and I'm not interested in saving a mere few dollars.

Cheers,

Sander.
Sep 20, 2010, 09:17 AM
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Oh, adding to that, the HK Turnigy 3A UBEC (switching) is great too, but they vary with batches, some are great (very low noise) others are okay but are more noisy. I always use one of these on my builds if >3 servos.

Cheers,

Sander.
Sep 20, 2010, 09:21 AM
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boopidoo's Avatar
Do you think it's necessary to have an extra BEC if I use the Turnigy Plush 40A? The motor itself doesn't draw more then max 25A and I'm not using more then maximum 6 servos, most often only four.
Sep 20, 2010, 09:34 AM
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Quote:
Originally Posted by boopidoo
Do you think it's necessary to have an extra BEC if I use the Turnigy Plush 40A? The motor itself doesn't draw more then max 25A and I'm not using more then maximum 6 servos, most often only four.
I use that ESC on my FunJet a lot, with three or four HS65HB servos, works fine, but on larger planes I add the external BEC and only route the signal wire to the ESC.

Cheers,

Sander.
Sep 21, 2010, 03:55 AM
Suspended Account
Upon popular request I'd like to show how to get the KPV-VSN505PHB to behave, or basically reduce its RFI to levels which are at, or below, the noise floor. The solution is pretty simple. After taking a closer look at the KPC-VSN505PHB it was clear that all of the RFI was radiated from the camera wires.

How to remedy this? Start with twisting the camera wires (which means removing the outer protective sleeving). Then feed the twisted cable (VCC, GND and VID) through a ferrite ring >4 times, this solves the problem. Below are the spectrum analyzer plots that show the results.



Fig 1. Baseline plot from 300 to 500MHz, KPC-VSN505PHB camera off.



Fig 2. KPC-VSN505PHB camera on, no more RFI.



Fig 3. Twisted camera cable fed through ferrite ring >4 times.

Cheers,

Sander.
Sep 21, 2010, 04:01 AM
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trappy's Avatar
hmmm, I guess that'll shut up the hayabusa driving redneck? thanks, excellent post as always sander ... time to revive the 505's from my drawer!
Sep 21, 2010, 04:10 AM
On a holiday?
boopidoo's Avatar
Thanks Sander! I guess I'll have to order this camera after all.
Sep 21, 2010, 07:50 AM
my karma ranover my dogma
galaxiex's Avatar
Thanks sander, nice to see someone with the know-how and equipment to test this stuff doing this.

Did you take any other steps, like making sure the camera case was grounded?

I know you say it's all radiated from the wires, but there was a report of paint inside the camera case, sometimes preventing said case from being solidly grounded.
It may be a minor point, but surely it helps?


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