Amplification warning

[gpauk]

Word to the wise to those adding amplifiers to the TX (controller 5.8ghz) or wifi (2.4ghz repeater and camera). Be aware of the maximum input of the amplifier. Most amplifiers can only handle 20dbm (100mw) maximum input (many much less).

It is well known that the controller has two modes CE = 25mw (14dbm) and FCC = 126mw (21dbm). I just finished testing using an RF Power Meter and these power levels are accurate.

The published power level for the repeater is 17dbm (50mw). My testing with the RF Power Meter is showing 21dbm (126mw).
There is no published power level for the camera. My testing with the RF Power Meter is showing 21dbm (126mw).

The word to the wise, for best results and the life of your amplifier, be sure you use an attenuator to lower the power level before input into your amplifier.

Happy flying.

What RF power meter did you use?
I think I'll finally weaken and stick the stock repeater on the analyser, see what the power spectrum looks like... I'd resisted opening it up but the more I read from you guys that have.........

Good advice though for those with out test gear.
The PA I use for the 5.8GHz has +22dBm gain, so the tx has to be attenuated a fair bit....

 

[themosttoys]

What RF power meter did you use?
I think I'll finally weaken and stick the stock repeater on the analyser, see what the power spectrum looks like... I'd resisted opening it up but the more I read from you guys that have.........

Good advice though for those with out test gear.
The PA I use for the 5.8GHz has +22dBm gain, so the tx has to be attenuated a fair bit....

RF Power Meter = ImmersionRC http://www.immersionrc.com/product-deta ... er%20Meter

For the TX, just put it in CE mode and it will be 14dbm (25mw).

Cheers

 

[helixaviator]

Yes I am a bit confused as well. So if the camera has circular polarized antennas I am assuming the repeater has circular polarized as well since they appear to be the same. Is it best to match LHCP in transmitter with LHCP in receiver or do you want LHCP in one and RHCP in the other? If the cam is using LHCP does this mean its not wise to be using the linear polarized 8dbi tp link omni antenna since you dont want to mix linear with circular polarized?

Always best to use matching antennas. Especially with circular polarization, you MUST match, so if you use RHCP on the camera, you must use RHCP on the repeater (ore vise versa). Linear antennas work with circ pol but you lose 3dbi of gain. Ex: if you have a circ pol on the camera (like stock) and you use a 8dbi whip on the repeater, the 8dbi whip will perform like a 5dbi.

Great thank you for taking the time to answer our posts! Looks like I am going to be adding an antenna to the camera after all.

 

[themosttoys]

Great thank you for taking the time to answer our posts! Looks like I am going to be adding an antenna to the camera after all.

You are welcome, glad I could help.

Good luck and happy flying.

 

[flycamdfw]

Does the original Phantom transmitter come with the US power output set or does the back of the transmitter need the turn of the screwdriver to up the power. Again, original trans - When I turn it on it just flashes the light a couple of times and stays on.

Thanks

Ray-

 

[Pull_Up]

As per the manual.... CE mode by default (one beep when you switch on), you'll need to follow the procedure to get into FCC mode (2 beeps on transmitter switch on).

 

[gpauk]

What RF power meter did you use?
I think I'll finally weaken and stick the stock repeater on the analyser, see what the power spectrum looks like... I'd resisted opening it up but the more I read from you guys that have.........

Good advice though for those with out test gear.
The PA I use for the 5.8GHz has +22dBm gain, so the tx has to be attenuated a fair bit....

RF Power Meter = ImmersionRC http://www.immersionrc.com/product-deta ... er%20Meter

For the TX, just put it in CE mode and it will be 14dbm (25mw).

Cheers

FYI the immersion RC one should be considered to be about +/- 3dB accuracy. I got hold of one and tested it. It's very good value and excellent for relative measurements though.
On the other hand -- I suspect there's a fair bit of variation in the output of the dji Tx (not unreasonably), as there seems to be significant variation in the range people experience.....

 

[gpauk]

What RF power meter did you use?
I think I'll finally weaken and stick the stock repeater on the analyser, see what the power spectrum looks like... I'd resisted opening it up but the more I read from you guys that have.........

Good advice though for those with out test gear.
The PA I use for the 5.8GHz has +22dBm gain, so the tx has to be attenuated a fair bit....

RF Power Meter = ImmersionRC http://www.immersionrc.com/product-deta ... er%20Meter

For the TX, just put it in CE mode and it will be 14dbm (25mw).

Cheers

That's ok for most wifi booster type amps but would overdrive mine.. So I added a microstrip attenuator...

 

[helixaviator]

themosttoys, do you have a link for the attenuator that you used?

Thanks!

 

[themosttoys]

RF Power Meter = ImmersionRC http://www.immersionrc.com/product-deta ... er%20Meter

For the TX, just put it in CE mode and it will be 14dbm (25mw).

Cheers

That's ok for most wifi booster type amps but would overdrive mine.. So I added a microstrip attenuator...

Wise move.

 

[themosttoys]

themosttoys, do you have a link for the attenuator that you used?

Thanks!

I have a number of 3db and 6db hanging around. The one I'd recommend is something like this: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... OC:US:3160

 

[helixaviator]

don't you need rp-sma?

 

[themosttoys]

don't you need rp-sma?

I used converters. If I make it permanent, I'll change the cable out of the camera from u.fl -> rp-sma to u.fl -> sma (eliminate one converter). The amp I'm using is rp-sma, so I still need that converter (unless I change the amp.)

 

[theSelf]

hi everyone- since normally if you have a linearly polarized antenna on the VTX you must have a linear (non circularly polarized) antenna on the VRX and equally if you have a circularly polarized antenna on the VTX you must have a circularly (non linearly) polarized (polarized in the same direction to the right or left) antenna on the VRX.. from this thread, it's news to me that the camera (VTX) antenna is circularly polarized.. I'm confused since for some time I've been looking at all the successful attempts to extend range people have had by only updating one or both of the VRX/repeater's antennas with linearly polarized omni directional or patch (non circularly polarized) antennas like those from TP-link (which I have invested in myself already but yet to install)...can anyone explain how this is working well (linearly polarized antennas on the repeater/VRX receiving signal from the stock vision camera's VTX circularly polarized antenna/s?.. Are there two antennas on the camera/vtx (like the repeater or only one and if the camera/VTX's antenna is circularly polarized for sure is the stock camera/VTX antenna right hand or left circularly polarized?

also - on the side- I have this (unused) 1W 2.4GHz wifi booster/amplifier- http://twins-net.blogspot.com/2012/11/a ... oster.html (I got it almost 2 years ago to boost my FRsky TX signal for long range fixed wing FPV as proven with rangevideo but still untested)- is the conclusion for if I were to use this on my VRX/DJI repeater (too big/heavy for mounting onto the p2v) that I will need an attenuator and if so from looking at the amplifier's specs, can anyone recommend an appropriate specific model that will work well?

Thanks for anyone's feedback in advance!

 

[themosttoys]

hi everyone- since normally if you have a linearly polarized antenna on the VTX you must have a linear (non circularly polarized) antenna on the VRX and equally if you have a circularly polarized antenna on the VTX you must have a circularly (non linearly) polarized (polarized in the same direction to the right or left) antenna on the VRX.. from this thread, it's news to me that the camera (VTX) antenna is circularly polarized.. I'm confused since for some time I've been looking at all the successful attempts to extend range people have had by only updating one or both of the VRX/repeater's antennas with linearly polarized omni directional or patch (non circularly polarized) antennas like those from TP-link (which I have invested in myself already but yet to install)...can anyone explain how this is working well (linearly polarized antennas on the repeater/VRX receiving signal from the stock vision camera's VTX circularly polarized antenna/s?.. Are there two antennas on the camera/vtx (like the repeater or only one and if the camera/VTX's antenna is circularly polarized for sure is the stock camera/VTX antenna right hand or left circularly polarized?

also - on the side- I have this (unused) 1W 2.4GHz wifi booster/amplifier- http://twins-net.blogspot.com/2012/11/a ... oster.html (I got it almost 2 years ago to boost my FRsky TX signal for long range fixed wing FPV as proven with rangevideo but still untested)- is the conclusion for if I were to use this on my VRX/DJI repeater (too big/heavy for mounting onto the p2v) that I will need an attenuator and if so from looking at the amplifier's specs, can anyone recommend an appropriate specific model that will work well?

Thanks for anyone's feedback in advance!

Circular polarized (circ pol) and linear are compatible. The only draw back will be a loss of 3dbi. Aka, if you use a 8dbi linear antenna on the VRX / repeater it will only have 5dbi of gain (max) because the VTX is circ pol.

Specific to circ pol, you can NOT mix RHCP & LHCP. Aka, if you use a LHCP (left-hand) on one side (TX), you MUST use LHCP on the other (RX).

The amp at your link has an input trigger max or 20dbm with a recommended range of 9 to 13dbm. This is right on the line, depending on the internals of the amp, it could simply pass the signal through (essentially no amplification), it could cause internal damage (over time) or it could automatically reduce gain (this also reduces output efficiency.) The best solution would be to use an attenuator (6db should be fine.)

 

[theSelf]

hi everyone- since normally if you have a linearly polarized antenna on the VTX you must have a linear (non circularly polarized) antenna on the VRX and equally if you have a circularly polarized antenna on the VTX you must have a circularly (non linearly) polarized (polarized in the same direction to the right or left) antenna on the VRX.. from this thread, it's news to me that the camera (VTX) antenna is circularly polarized.. I'm confused since for some time I've been looking at all the successful attempts to extend range people have had by only updating one or both of the VRX/repeater's antennas with linearly polarized omni directional or patch (non circularly polarized) antennas like those from TP-link (which I have invested in myself already but yet to install)...can anyone explain how this is working well (linearly polarized antennas on the repeater/VRX receiving signal from the stock vision camera's VTX circularly polarized antenna/s?.. Are there two antennas on the camera/vtx (like the repeater or only one and if the camera/VTX's antenna is circularly polarized for sure is the stock camera/VTX antenna right hand or left circularly polarized?

also - on the side- I have this (unused) 1W 2.4GHz wifi booster/amplifier- http://twins-net.blogspot.com/2012/11/a ... oster.html (I got it almost 2 years ago to boost my FRsky TX signal for long range fixed wing FPV as proven with rangevideo but still untested)- is the conclusion for if I were to use this on my VRX/DJI repeater (too big/heavy for mounting onto the p2v) that I will need an attenuator and if so from looking at the amplifier's specs, can anyone recommend an appropriate specific model that will work well?

Thanks for anyone's feedback in advance!

Circular polarized (circ pol) and linear are compatible. The only draw back will be a loss of 3dbi. Aka, if you use a 8dbi linear antenna on the VRX / repeater it will only have 5dbi of gain (max) because the VTX is circ pol.

Specific to circ pol, you can NOT mix RHCP & LHCP. Aka, if you use a LHCP (left-hand) on one side (TX), you MUST use LHCP on the other (RX).

The amp at your link has an input trigger max or 20dbm with a recommended range of 9 to 13dbm. This is right on the line, depending on the internals of the amp, it could simply pass the signal through (essentially no amplification), it could cause internal damage (over time) or it could automatically reduce gain (this also reduces output efficiency.) The best solution would be to use an attenuator (6db should be fine.)

thanks for your reply thermosstoys- you are helping greatly and I appreciate it..

so to confirm-both of the p2v camera's VTX's 2 STOCK circularly polarized antennas are LHCP and not RHCP..? (not planning on changing the camera/VTX's antennas) ...Harder to find LHCP clover leafs etc.. just trying to match on the repeater end with a correctly circularly polarized antenna..

I currently have this 14dbi patch antenna- http://www.amazon.com/dp/B003CFATOC/ref ... E06YCPLW6X

and these 2 U.FL Mini PCI to RP-SMA Pigtail Antenna WiFi Cables http://www.amazon.com/U-FL-RP-SMA-Pigta ... 005UWD0EG..

I was thinking of getting this 8dbi omini directional antenna to swap out from the patch when more convenient... http://www.newegg.com/Product/Product.a ... 6833997226 or this more portable smaller 5dbi equivalent- http://www.newegg.com/Product/Product.a ... 6833997208

however, should I Instead get this 2.4Ghz cloverleaf circularly polarized antenna (it is RHCP though) http://www.readymaderc.com/store/index. ... cts_id=813 instead of the 8dbi or 5dbi linear omnidirectional antennas? (would the clover leaf produce better range than the 5dbi, 8dbi or even 14dbi linear antennas above)? Should this antenna be RHCP or LHCP (connected to the VRX/repeater only based on which way you confirm the stock camera/VTX's antennas are polarized)? Cloverleaf or skew planar? (Should I get rid of the huge 14 dbi patch antenna altogether and get this 9dbi helical antenna instead of the patch (also RHCP or LHCP equivalent): http://www.readymaderc.com/store/index. ... cts_id=487

So amplifiers can indeed make a difference connected to the receiver (as opposed to transmitter)? (I would think the transmitted signal could and would only be amplified..you can amplify an incoming (unamplified) signal to the VRX/repeater for better reception also? So the 6db antennuators in the above ebay link you posted would best over the 3db ones?

You mentioned also in an earlier post that you can upgrade the stock p2v TX/remote controller 5.8GHz antenna to a 7dbi whip or 11 dbi patch- are there any specific proven versions of these antennas you can recommend and any specific info anywhere already posted on how to change the stock TX antenna?

Gratefully,

Justin

 

[RemE]

As an additional data point, I just added a RP-SMA connector to a stock range extender to add an 8db Omni whip as others have done. I put my immersion power meter on it just now and measured 79mW so they do seem to vary I guess?

 

[BJay]

don't you need rp-sma?

I used converters. If I make it permanent, I'll change the cable out of the camera from u.fl -> rp-sma to u.fl -> sma (eliminate one converter). The amp I'm using is rp-sma, so I still need that converter (unless I change the amp.)

http://www.ebay.com/itm/161171689186?_t ... EBIDX%3AIT

A converter for the lazy ones who are interested

 

[themosttoys]

thanks for your reply thermosstoys- you are helping greatly and I appreciate it.. Thanks, you are welcome

so to confirm-both of the p2v camera's VTX's 2 STOCK circularly polarized antennas are LHCP and not RHCP..? (not planning on changing the camera/VTX's antennas) ...Harder to find LHCP clover leafs etc.. just trying to match on the repeater end with a correctly circularly polarized antenna.. Correct, the stock antennas are LHCP

I currently have this 14dbi patch antenna- http://www.amazon.com/dp/B003CFATOC/ref ... E06YCPLW6X Great linear patch antenna.

and these 2 U.FL Mini PCI to RP-SMA Pigtail Antenna WiFi Cables http://www.amazon.com/U-FL-RP-SMA-Pigta ... 005UWD0EG.. Link didn't work for me, but I'm sure they are fine. It will not make a real world difference, but if given the choice I use rg178 cables for permanent installations.

I was thinking of getting this 8dbi omini directional antenna to swap out from the patch when more convenient... http://www.newegg.com/Product/Product.a ... 6833997226 or this more portable smaller 5dbi equivalent- http://www.newegg.com/Product/Product.a ... 6833997208 Both good omni antenna's

however, should I Instead get this 2.4Ghz cloverleaf circularly polarized antenna (it is RHCP though) http://www.readymaderc.com/store/index. ... cts_id=813 instead of the 8dbi or 5dbi linear omnidirectional antennas? A great antenna, I'm a BIG IBCrazy fan, but for this situation I'd go with Skew Planar rather than Cloverleaf.(would the clover leaf produce better range than the 5dbi, 8dbi or even 14dbi linear antennas above)? There is not a simple answer, the linear antennas have higher gain and theoretically greater range, but it also depends on the ontenna on the other side and flying conditionsShould this antenna be RHCP or LHCP (connected to the VRX/repeater only based on which way you confirm the stock camera/VTX's antennas are polarized)? Cloverleaf or skew planar? (Should I get rid of the huge 14 dbi patch antenna altogether and get this 9dbi helical antenna instead of the patch (also RHCP or LHCP equivalent): http://www.readymaderc.com/store/index. ... cts_id=487 Another great IBCrazy antenna. Personally I would / will go with a Skew Planar and Helical. It's not that much more inconvenient than the whips and produces better overall results for me.

So amplifiers can indeed make a difference connected to the receiver (as opposed to transmitter)? (I would think the transmitted signal could and would only be amplified..you can amplify an incoming (unamplified) signal to the VRX/repeater for better reception also? Yes, most amps are bidirectional and will also amplify RX signal, but the overall effect will be much less than amplifying TX.So the 6db antennuators in the above ebay link you posted would best over the 3db ones? In my situation they are best, although either will work fine (I initially used 3db and it worked fine but after testing my stock TX output, I switched to 6db).

You mentioned also in an earlier post that you can upgrade the stock p2v TX/remote controller 5.8GHz antenna to a 7dbi whip or 11 dbi patch- are there any specific proven versions of these antennas you can recommend and any specific info anywhere already posted on how to change the stock TX antenna? I use this http://www.amazon.com/dp/B00E37BPKA/ref ... 1_ST1_dp_1 and this http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... OC:US:3160

Gratefully,

Justin

 

[themosttoys]

don't you need rp-sma?

I used converters. If I make it permanent, I'll change the cable out of the camera from u.fl -> rp-sma to u.fl -> sma (eliminate one converter). The amp I'm using is rp-sma, so I still need that converter (unless I change the amp.)

http://www.ebay.com/itm/161171689186?_t ... EBIDX%3AIT

A converter for the lazy ones who are interested

This is an example of what I used: http://www.ebay.com/itm/SMA-male-to-RP- ... 233349e8bf