Espritmodel.com Telemetry Radio
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Old Nov 23, 2011, 03:37 AM
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Originally Posted by daronj View Post
By the way, here is a quick 60 second sample of what I have. This is all well within 1/4 mile.
This really looks like if you would fly with the stock antennas. You are sure you use circular polarized antennas?

Markus
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Old Nov 23, 2011, 05:11 PM
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Prague, Czech_Republic
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Originally Posted by IBCrazy View Post
That looks like a camera or RX problem. Nothing to do with the antenna. It looks like a section of the video feed loses synchronization or the levels shift. It could be a setting in the camera. In any case, I think your camera is at fault. Do you have another camera to try?

-Alex
Thanks for the answer, Alex!
it seems that you shown me the"Columbus egg".
I was suspecting everything - expect the camera. I haven't made all tests yet but this broken image is really most dependent on the contens of a video frame so it's the most probably problem of the camera.
It seems to be bad coincidence that camera is providing non standard video with weak sync frames nad receiver destroys it even more... (RX output is from the factory AC coupled.) I will test diferent camera but I have to get some first. I have second camera, but this is the same type so most probably having the same problem.
Just BTW- this is the camera I use... http://www.ebay.com/itm/Mini-Pinhole...item415ccf6bf8

I can confirm, that cloverleaf is innocent in that problem!
Thanks for your guides and all work for us!
Roman
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Old Nov 23, 2011, 10:50 PM
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Originally Posted by markus123456 View Post
There is a simple 7805 linear voltage regulator inside. You best drive it off a 2s battery as with 3s it may get's too hot in summer days. The bad thing is that if this happens, it all of a sudden will turn to a black picture. So if you want to stay on the save side, either use an external DC/DC converter that goes down to around 7 volts, or use a 2S battery for it. I personally run it also off a 3s battery, so far without DC/DC regulator, but I'm aware of the problem and make sure it gets some cooling if it's really hot. Not really a problem here at this time of the year though. brrrr... winter is coming.

Markus
Thanks Markus. That's actually an even better setup as I was originally planning on slaving power from the power supply from my latest (not so great color contrast) goggles...which uses a 2S battery. Now I shouldn't have to worry about carrying around a separate battery for the VRx.
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Old Nov 23, 2011, 11:21 PM
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yzguy's Avatar
Florida
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Quote:
Originally Posted by markus123456 View Post
There is a simple 7805 linear voltage regulator inside. You best drive it off a 2s battery as with 3s it may get's too hot in summer days. The bad thing is that if this happens, it all of a sudden will turn to a black picture. So if you want to stay on the save side, either use an external DC/DC converter that goes down to around 7 volts, or use a 2S battery for it. I personally run it also off a 3s battery, so far without DC/DC regulator, but I'm aware of the problem and make sure it gets some cooling if it's really hot. Not really a problem here at this time of the year though. brrrr... winter is coming.

Markus
anyone know if there are different 305's? I have one that is slightly different(different channels)

http://www.rangevideo.com/index.php?...roducts_id=213



it is listed right on it, that it works with 12V, and I have only run it on 3S. I did not know I should be careful about that. (it gets hot here in FL)
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Old Nov 24, 2011, 12:02 AM
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Australia, SA, Adelaide
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Yes there is two types of 305's that i am aware of - that one you listed from range video in 5.8 is compatible with there tx's were say the 305 in 5.8 from Foxtech are compatible with there tx and both have different channels to each other.
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Old Nov 24, 2011, 02:41 AM
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Originally Posted by yzguy View Post
anyone know if there are different 305's? I have one that is slightly different(different channels)

http://www.rangevideo.com/index.php?...roducts_id=213



it is listed right on it, that it works with 12V, and I have only run it on 3S. I did not know I should be careful about that. (it gets hot here in FL)
The difference are some pull up / pull down resistors inside the HF module of the reciver. Those recivers HF (same holds true for the tx) modules come basically in three flavours. There is the 'A', 'B' and 'E' band available. The difference is the set of channel frequencies used. 'A' is what's legal in the US, 'B' is what would be legal in the EU (haven't seen any real live products with those module types though), and 'E' is kind of a channel mix choosen such that at least one or two channels fall into the legal frequency range of virtually every country on this planet.

In theory you could modify your 'A' type reciver to become an 'E' or 'B' and vice versa. The "procedure" is to open up the inner HF module and replace some pretty tiny smd resistors. The a bit less difficult aproach would be to replace the HF module all together (they are available for around $10 - $15 in various shops) but it's questionable if it's worth the effort considering the fairly low rx price.

Attached you find a little table listing the frequency to band mapping of this rx/tx familly.

HTH

Markus
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Old Nov 24, 2011, 04:02 PM
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1280MHz Cl/SPW VTX/VRX pair ... estimated range ??

Hi

I just need to know the expected range of a 1280MHz CL/SPW VTX/VRX pair ... I know there are several factors that affect the range but I need to know a round figure you know something like (From ??? to ???) ... in other words the maximum so I don't exceed it

Also does the rule of (Altitude should be at least 1/10th of the distance) apply to the radiation patterns of the CL/SPW antennas ??

Thanks a lot

Khaled
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Old Nov 24, 2011, 04:33 PM
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Quote:
Originally Posted by khaled_abobakr View Post
Hi

I just need to know the expected range of a 1280MHz CL/SPW VTX/VRX pair ... I know there are several factors that affect the range but I need to know a round figure you know something like (From ??? to ???) ... in other words the maximum so I don't exceed it

Also does the rule of (Altitude should be at least 1/10th of the distance) apply to the radiation patterns of the CL/SPW antennas ??

Thanks a lot

Khaled
The rule of thumb 1/10 can be safely applied generally to all kinds of radio transmission in the FPV section, regardless the type of antenna.
If you like heading for trouble or want more precise values, you can estimate your margins and use a range calculator as this one:

http://www.compex.com.sg/RangeCalFull.aspx
or this one:
http://www.afar.net/rf-link-budget-calculator/

...while maintaining the required Fresnel Zone for the given frequency band.
Therefore:
the lower the frequency, the higher you need to fly at a given distance.

Keep in mind that your RC-Control system might require more Fresnel Clearance (means, you need to fly higher) than your video link, if its frequency is lower than that of your video link.

Hartwig
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Old Nov 25, 2011, 05:59 AM
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Quote:
Originally Posted by hartwig View Post
The rule of thumb 1/10 can be safely applied generally to all kinds of radio transmission in the FPV section, regardless the type of antenna.
If you like heading for trouble or want more precise values, you can estimate your margins and use a range calculator as this one:

http://www.compex.com.sg/RangeCalFull.aspx
or this one:
http://www.afar.net/rf-link-budget-calculator/

...while maintaining the required Fresnel Zone for the given frequency band.
Therefore:
the lower the frequency, the higher you need to fly at a given distance.

Keep in mind that your RC-Control system might require more Fresnel Clearance (means, you need to fly higher) than your video link, if its frequency is lower than that of your video link.

Hartwig
Thanks a lot ... I really appreciate that .. What about the estimated range ??
BTW...I"m using 2.4 Ghz R/C link Futaba Fasst in stock form

Khaled
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Old Nov 25, 2011, 07:56 PM
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Quote:
Originally Posted by hartwig View Post
Therefore:
the lower the frequency, the higher you need to fly at a given distance.


Hartwig
I would like to test this in real life, I fly 1010mhz and I can get down low at 10km, does someone on a higher frequency get low at 10km?

Mark
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Old Nov 25, 2011, 08:43 PM
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Quote:
Originally Posted by mark hitchman View Post
I would like to test this in real life, I fly 1010mhz and I can get down low at 10km, does someone on a higher frequency get low at 10km?

Mark
Pls specify the exact altitude level.
Of course the result you get also depends on the area. I am referring to a flat surface, no hills or valleys between launch site and aircraft. One of my tests got me out past >3.2km at <20m AGL with me standing on the ground. Video link was on 2.4GHz and the RC on 433MHz.
Since there was no Fresnel Clearance fpr the RC link, this was the link that got affected first.
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Old Nov 25, 2011, 10:07 PM
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Las Vegas, NV
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Alex,

Quicky question on the CL/SPW sets you sell for 5.8G. What exact freq are they built to?
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Old Nov 25, 2011, 11:41 PM
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probqbly the legal freq for region they qre being shipped to
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Old Nov 26, 2011, 12:02 AM
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Originally Posted by chatch15117 View Post
probqbly the legal freq for region they qre being shipped to
And there are four legal freq's for 5.8G in the U.S. You should get best performance by setting the VTx/VRx freq to what the antenna is built for.
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Old Nov 26, 2011, 12:20 AM
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try thre one its built for then
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