Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Jul 05, 2012, 12:37 PM
Aerial Photography
Canada, BC, Vancouver
Joined Jun 2012
103 Posts
Discussion
RangeLink and 1.3G interference

Hey. I am getting a lot of interference on my 1.3G video system with the RangeLink. I am using this setup from bevrc (2 rx for diversity): http://www.bevrc.com/bev-13g-1500mw_p82.html
I am using the H channel (1.32G) which is the only one that will not interfere with the NAZA GPS.

I would like to know what I can do about this interference. Maybe put a low pass filter in RL? But it is supposed to have one already.

I have read that getting some Lawmate 1.2 tx/rx will solve the problem due to their superior filtering but before I go that route I would like to know what your guys experience is with GPS interference and LM and what channel should be used to avoid GPS problems.

By the way I am using a Hex for the platform and have already separated the GPS and Tx antenna as far as I can.

I am going to be using SPW and cloverleaf antennas.

Thanks for your input.
kdrcguy is offline Find More Posts by kdrcguy
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 05, 2012, 12:54 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
Those digital display video Rx's pick up interference from all UHF Txs and a low pass filter
won't help. The only way you can use em is if you separate the UHF Tx antenna
from the ground station by 10-20 feet. Get a Racewood or Lawmate Rx.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 05, 2012, 01:10 PM
Aerial Photography
Canada, BC, Vancouver
Joined Jun 2012
103 Posts
Aw, that is too bad. I just found a $15 LPF too and was happy it would solve my problem. I guess I have to change out my entire video system.

Any ideas as to the interference with LM 1.2G equipment and GPS?

Maybe I should go to 2.4G video. How is it for UHF interference and obstacle penetration compared to 1.3g?

Thanks for the quick reply.
kdrcguy is offline Find More Posts by kdrcguy
Reply With Quote
Old Jul 05, 2012, 01:16 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
From what I've seen, the problem between 1.2Ghz video and GPS is more related to
the quality of the GPS Rx. Some of them pick up more noise than others.
I'm surprised that 1320Mhz works better for you than 1280Mhz, as GPS operates at 1.5Ghz
so I'd expect the higher video frequency (closer to it) to be worse.
The OMM Dual Notch filter can fix that problem, but it doesn't appear to be available any more.

1.3Ghz definitely has better penetration than 2.4Ghz, and there's so much more external
noise on 2.4Ghz band.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 05, 2012, 01:31 PM
Aerial Photography
Canada, BC, Vancouver
Joined Jun 2012
103 Posts
I was surprised the 1320Mhz worked better too but I always thought that GPS works at both, 1.5Ghz and 1.2Ghz, at least according to wikipedia: "All satellites broadcast at the same two frequencies, 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal)" http://en.wikipedia.org/wiki/Global_Positioning_System

So I assumed that being right between the two is the best thing. I also have a 1400Mhz low pass filter on my video tx.

So the recommendation is to get some LM equipment. Where would I get some genuine LM TX/RX? I have read that some sell non-genuine LM products. They are out of stock everywhere but would Foxtechfpv or ReadyMadeRc be safe to purchase from?

Thanks again for the lightning reply, you are awesome.
kdrcguy is offline Find More Posts by kdrcguy
Reply With Quote
Old Jul 05, 2012, 01:32 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
Personally, I like the Racewood Rx more than the Lawmate Rx because its four frequencies
all overlap directly with the Sunsky Tx, while Lawmate does not.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 05, 2012, 01:38 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
BTW, Civilian GPS Rx generally depend only on the L1 band signal. L2 is encrypted
and meant for use by Military grade GPS Rx. Some high end civilian GPS Rx
do some tricks to gather information directly from the L2 carrier signal (without decrypting
it), but any GPS should be able to get a full lock with nothing but the L1 band signal.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 05, 2012, 01:43 PM
Aerial Photography
Canada, BC, Vancouver
Joined Jun 2012
103 Posts
What kind of benefits does the overlap with Sunsky TX give?

I found this one here http://www.dronesvision.com/racewood...as-blue-label/

If I purchase the rx only can I use it with my bevrc 1.3G tx? they have the same frequency (1320Mhz). The racewood tx is 500mw while the bevrc is claimed to be 1500mw so I want to use the highest power output while saving some $.
kdrcguy is offline Find More Posts by kdrcguy
Reply With Quote
Old Jul 05, 2012, 01:52 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
It's also available at RMRC.
Yes it works fine with the BEVRC 1.2-1.3Ghz Tx (is rebadged Sunsky).
1500mW is way way more power than 99% of folks need.
The current out and back world record (100km) was set with an 850mW video Tx.
The problem with high powered video Tx is they thrash other electronics onboard
the plane (GPS, RC Rx, sometimes servos.. etc) but only provide marginal range
improvement. Takes 4x the power (6dB) to go 2x the distance, and you can get the
same 6dB with a higher gain Rx antenna without the onboard interference.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 05, 2012, 02:00 PM
Aerial Photography
Canada, BC, Vancouver
Joined Jun 2012
103 Posts
Hm that is a good point. I had no idea they are so bad for the electronics.
I think the 1500mW is overrated but even if it is it is still quite a bit and the
reason I got that much power was to have insurance and not lost the signal
behind obstacles.

However I am stating to understand that it is not the power output that matters
but the penetrating power of the signal.

I will be getting a different tx then, a 500mW racewood.

I was not able to find any racewood stuff on RMRC. Could you link me to
the TX and RX?

Again, thank you for lightning fast response.
kdrcguy is offline Find More Posts by kdrcguy
Reply With Quote
Old Jul 05, 2012, 03:19 PM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
1.3 Ghz Receivers are here http://www.readymaderc.com/store/ind...cPath=11_34_44
I don't know if some of the RMRC Txs are Racewood or not, but all their Txs will only
transmit on 2 channels 1258 and 1280 when sold in the US.
http://www.readymaderc.com/store/ind...cPath=11_30_38

I use the Sunsky FOX800 (bought directly from Sunsky) and Racewood Rxs
which play just fine with Rangelink UHF.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 05, 2012, 04:11 PM
Aerial Photography
Canada, BC, Vancouver
Joined Jun 2012
103 Posts
I ordered the racewood 500mw tx and rxs from dronesvision. Hope they are genuine
racewood equipment. Hopefully that will fix any issues with RL.

BTW I live in Canada but I don't know if this rule applies here.

A big thanks to you for all the help.

Dima
kdrcguy is offline Find More Posts by kdrcguy
Reply With Quote
Old Jul 06, 2012, 06:44 AM
Jose Angel
Espaņa, Comunidad de Madrid, Madrid
Joined Nov 2010
158 Posts
Quote:
Originally Posted by Daemon View Post
I use the Sunsky FOX800 (bought directly from Sunsky) and Racewood Rxs
which play just fine with Rangelink UHF.
I have ordered a rangelink and I'm looking for a new VTX....

Ian, do you mean this one?
http://www.sunsky-online.com/view/13...ransmitter.htm
The page does not show the exact channel frequency....
Currently have the racewood RX (1240,1280,1320,1360) and the 400mw RMRC TX (1080,1120,1160,1200,1240,1280,1320,1360)

So, no filters needed with your combo rangelink, racewood and FOX800, isn't it?
alvarezpja is offline Find More Posts by alvarezpja
Reply With Quote
Old Jul 06, 2012, 11:22 AM
Registered User
Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,200 Posts
Yes, that's the Sunsky Tx. It has the same frequencies as your 400mW Tx.
And yes, no external filters necessary to work with Rangelink UHF and Racewood video Rx.

ian
Daemon is online now Find More Posts by Daemon
RCG Plus Member
Old Jul 06, 2012, 11:50 AM
Jose Angel
Espaņa, Comunidad de Madrid, Madrid
Joined Nov 2010
158 Posts
Quote:
Originally Posted by Daemon View Post
Yes, that's the Sunsky Tx. It has the same frequencies as your 400mW Tx.
And yes, no external filters necessary to work with Rangelink UHF and Racewood video Rx.

ian
Thanks Ian
alvarezpja is offline Find More Posts by alvarezpja
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! Terrible problems with 1.28GHz video interfering with UHF Equiptment! Kahuna717 FPV Talk 75 Aug 08, 2012 06:27 PM
Discussion 1.2GHz interfering with 35MHz RC teopbako FPV Talk 3 Feb 20, 2012 11:59 AM
Discussion 72mhz amped interfering with 1.2 video? WBFlyer FPV Talk 15 Dec 25, 2011 12:48 AM
For Sale ALIGN 3G Programmable FBL units V2.1, 3G USB Link Primus2 Aircraft - Electric - Helis (FS/W) 1 Jul 29, 2010 02:49 AM
Channel 3 is interfering w/ 1 and 2 ??? rfaulk Beginner Training Area (Aircraft-Electric) 12 Jan 27, 2006 04:31 AM