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General Topics => RC General Topics => Topic started by: Immanuel on November 28, 2014, 04:25:40 PM



Title: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 04:25:40 PM
So I'm planning to add an apm with telemetry, after I'm done with my fpv , I was wondering since ill have 3 radio devices in my quad will there be any sort of interference, my radio is 2.4 ghz , and fpv is 5.8ghz , and d telemetry will be 3drobotics telemetry from quadkopters.com , I was wondering if ill have any interference??

, This is d setup im planning 3s 3300 Mah lipo for the quads power requirements, I use sunnysky motors. X2212 , and to power up my fpv a 1200mah , 3s lipo after I m done doing that , I will buy apm clone (quadkopters.com), telemetry and GPS , ill remove d kk board and power up the apm via power module with a 3300mah lipo, ( which will also power the escs ,motors .) , and d GPS and telemetry will be powered via the apm .., and the fpv will be powered with a 1200mah 3s lipo,
The total weight of my quad is now 1100grms, if I add the fpv and 3s 1200 Mah lipo it'll be abt 1400grms
Max with apm and GPS myt go up to 1400-1500grms , will my motors be able 2 handle d weight with a 3s 3300mah lipo ??( sunnysky x2212 says each motor with 3s 11.1 v lipo will give 700-800grms, with a 4s ill get abt 1100grms of thrust but I have oly a 3s battery :-\) or will I need a 4s lipo?? ( if I can get 8- 10 mins flight tym it'll be enough), I wanted to just check out before I bought anything ( i have already set up my reptile quad). Any suggestions are welcome..
Thank u all for ur help in advance..



Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 04:41:18 PM
What is the discharge C rating of your LiPo ?


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 04:45:07 PM
It's 25c ..


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 28, 2014, 04:46:33 PM
What frequency of telemetry do you plan to use? Make sure that your transmitter has greater range than your FPV system or else you will be able to watch it crash in FPV  :giggle: You will need an LC filter in your power system which you can DIY. You will also need circular polarised antennae for your FPV system. Assuming 800 grams thrust each, your setup should weigh no more than 1600 grams. I think battery life may only be 7-8 minutes, you can use the eCalc tool to check.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 04:51:48 PM
 :giggle: , I'm not planning 2 go on Long range flights just want 2 see first person from my quad , I don't need more than 800mtrs , for what will I need a low pass filter ? ( telemetry?, or fpv)


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 05:11:50 PM
As you are using separate LiPo for FPV, you can avoid LC filter,
Your Battery pack can deliver, 3.3x25 = 82.5 A Burst curreent. which is enough for 2212 motors- So there is no problem with your set up- but consider decreasing AUW anywhere it is possible.

 Circular polarized antenna is addon- Stock antenna will give enough range for your purpose I think.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 28, 2014, 05:16:20 PM
A low pass filter is different. I am talking about a simple LC filter to prevent RF noise from your power system from interfering with FPV.  It can be made for less than 50 bucks. Do you plan to use 415 MHz or 933 MHz telemetry? I don't know about the law regarding these bands. I would suggest you do some research on FPV such as from Oscar Liang's blog. I suggest you first install either FPV or the APM and get comfortable with it before adding more. If I were you, I would install the APM first and play around with it. I would not trust a Kk board with expensive FPV gear since APM has useful features such a return to launch that can save your gear in case of trouble.  And sooraj, wouldn't regular antenna cause signal loss in FPV due to multipath interference?


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 05:24:41 PM
Stock antenna can provide enough range with out interference, But we can increase quality and Range of signal by using circular polarized or even directional antenna, Also LC filter is optional, It is to be installed only when there is serious interference.
Our aim is min. weight.

Still I don't have hands on experience in FPV or FPV gear till now, I don't have any proof to it.
It is to be experimented. :)


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 05:25:35 PM
Yeah I thought about that,  didn't want to risk the fpv,  but u should know I'm  not much not using the original apm... , telemetry is 433mhz,  and yes @sooraj,  I ll use a separate battery for fpv,  the total weight with everything will be 1500-1600 grams,  I can reduce 85grms by removing d foam balls,  ill try Nd keep auw within 1500grms


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 05:27:53 PM
LC filter to be installed if there is serious interference or range issues.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 05:30:20 PM
I'll not have interference between fpv and tx I'm sure fpv is 5.8ghz,  radio 2.4ghz,  telemetry is 433mhz if there is interference I'll add a lc filter


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 05:33:07 PM
As u said I'm using a separate battery for fpv,  so I'll have no problems hopefully


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 28, 2014, 08:28:12 PM
One of the best things about living in India (related to multirotors) is the availability of really cheap APM clones. Since it is open source, quality should not be too much of an issue unless the component quality itself is bad. The bad part about buying clones is that DIYDrones receives less money for R&D. I have heard of possible interference between 2.4 and 5.8 GHz due to them being harmonic frequencies though I don't know much about that. The 433 MHz band is available for low power use as per the WPC website. I would suggest that you first buy the APM, GPS module and telemetry. Practise flying with it and get used to using Mission Planner. Maybe afterwards you can get into FPV. I have just started flying the same Reptile quad and I am planning to upgrade to APM. I am eagerly waiting to see what you do with it and all the best  :thumbsup:


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 08:38:18 PM
 How come 2.4GHz and 5.8GHz Harmonic?
Harmonic means even multiples of a frequency, ie; 1.2GHz,4.8GHz ,are Harmonics of 2.4GHz.

5.8G is not.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: pushpreet on November 28, 2014, 08:39:43 PM
If you do fpv, go get circular polarised antennas.
The stock ones will work ( blah, they are good for nothing ), but circular polarised antennas won't cost much and would instantly make your fpv setup better., without adding any weight.

The problem with the stock antennas is not range, rather, their orientation. If both the antennas are vertical, you'll be fine, but if even one of them changes its orientation ( you roll or pitch or quad too much or even hit your receiver antenna by mistake ), you will just loose all video and the panic starts. You don't want that.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 08:43:35 PM
Well, no comments here as I don't have hands on experiance on FPV,
Even I would prefer a circular polarized antenna over a omnidirectional antenna.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 28, 2014, 08:45:45 PM
Wow that was a really dumb mistake of me  :violent: . Forget what I said about harmonics, I don't know what I was thinking  :banghead:. I agree with pushpreet about the antenna, circular polarised are highly recommended, especially if there are obstacles nearby which cause interference or even dropouts in the video signal. Circular polarisation prevents interference from obstacles.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 08:51:28 PM
:rofl:


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 09:15:09 PM
Yeah I think I'll set it up with the apm first,  then order the fpv... With a circular polarised antenna,  and if I buy the original apm 2.6 it'll cost me something around  20k,  I checked it out,  customs for 3drobotics stuff is really high...,  and there will be no harmonics between 2.4 Nd 5.8.. Like sooraj said...,  A 6ch tx rx,  enough for apm2.6 right?


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 09:19:41 PM
NO, get a 9CH, for APM.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 28, 2014, 09:23:04 PM
6 channels ought to be enough unless you plan to control a gimbal. However 9 channels is definitely better. Which Tx do you have. It should have 2/3 position switches to get the most out of your flight modes.
EDIT: You probably should get a 9 channel radio with a 5 position switch to change flight modes. This will allow you to get the most out of your APM.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 09:28:40 PM
Ha, ha, he already says he is in to mission planning and FPV, so he definitely need a 9Ch, Why buy a 6Ch first and later 9Ch ???


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 28, 2014, 09:35:02 PM
He already has a quad, so I was asking whether he already has a 6ch radio and which one. I agree that 9ch is best, even the ArduCopter website says 6 channels minimum, 9 recommended. If he does not want to buy a new Tx, he could try mixing his channel 5 and 6 to get more flight modes though it depends on the model and is more convenient to get a new Tx.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 09:38:27 PM
Yeah I kept into consideration d apm requirements before I bought my tx,  it has a 3 position switch for channel fly,  and two position switch for channel 6, i can't add a gambolling to much of weight, maybe next time I'll upgrade it..


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 09:39:57 PM
I already bought a 6ch tx 3 months back :banghead:,  never at that time did I even dream about apm,  only kept it in consideration,  my initial budget was only 17k


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 09:40:12 PM
well then it's ok.
I haven't used APM, but I thought, need of extra channels for each of it's functions.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: linked on November 28, 2014, 09:43:56 PM
I am using APM 2.6, ublox gps and 900mhz telemetry with FS th-9X.
5.8ghz FPV works fine with 900mhz telemetry and 2.4GHZ radio. Better you use circular polarised antenna.
if you invest something on your radio get a 9 channel. otherwise 6 ch is good.




Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 09:45:41 PM
well,  There we have an experienced user.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 09:53:02 PM
Great, are u using the original apm 2.6?, @ linked


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 10:00:27 PM
 And thank u so much for all Ur help guys...  :)


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: radiocraft on November 28, 2014, 10:34:31 PM
Apm work better with 9ch rc and use 433mhz telemetry. I use the same no issues if signal interference yet. Don't go for 900mhz as our mobile companies use that frequency for communication.!


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 28, 2014, 10:37:23 PM
3DR introduced this two telemetry kits for coping with laws in different country, We can use 433MHz or 900MHz depending on what is allowed here.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: Immanuel on November 28, 2014, 10:45:21 PM
Yes I'm using the 433mhz one,  I'll invest on a better radio later on( maybe in 3 or 4 momths)


Title: Re:
Post by: rcrcnitesh on November 29, 2014, 03:08:23 PM
Well I saw a deal on eBay.com for an apm for 1$ it was an auction.
It was from a top rated seller.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: SK1701 on November 29, 2014, 05:11:47 PM
It would help if you posted a link. I believe that if it seems too good to be true, it probably is. 1$ is unreasonable, unless it is liquidation of defective pieces.


Title: Re: couple of doubts regarding apm , telemetry and fpv
Post by: sooraj.palakkad on November 29, 2014, 05:40:21 PM
yes dude it is true, if you are so lucky and no one but you bid on it before it ends, you can get it for 1$ !! (which probably won't happen as it is an APM for sale and people all around world will be watching it :( ) .
And this is how I sourced all my parts, dirt cheap !