Help choose 5.8 fpv


H

helloman1976

Ziptie Relocation Expert
Teco said:
Hi?
i am think buying a 5.8 TX/RX, I looking this one here, I just want to get range of 1 mile,

http://www.foxtechfpv.com/58g-500mw-long-range-8ch-txrx-p-246.html

or

http://www.foxtechfpv.com/58g-1000mw-vtx-p-679.html

any one with experience on 5.8 downlink?
Thanks
Click to expand...

There's a few rules when it comes to frequencies and I'll keep it simple. The lower the frequency the better the penetration through obstacles, the higher the frequency is the exact opposite. The lower the frequency the slower data will be send, the higher the frequency and you get the opposite. The lower the frequency the less power you need to send it the same range say 1 mile, the higher the frequency the more power you need to transmit the same distance say 1 mile. The lower the frequency the larger the antennas will be and the higher the frequency the smaller the antennas will get. That being said 5.8Ghz is great for line of sight only and will not penetrate through objects well at all. I personally run 900Mhz but cell phone bands run on 900Mhz so it isn't great inside the city limits but outside the city and it goes for miles without an issue. There's a video on YouTube that shows a 900Mhz system just like mine going 55Km. Because of so much interference on 900Mhz and the large size of the antennas most people who want good punch through power, the power to go through objects, go with 1.3Ghz. 1.3Ghz is pretty much an open band so you don't get any interference and the antennas aren't as big as the 900Mhz antennas which can get quite large and heavy.

If you still want to go with 5.8Ghz I'd highly recommend going to a different company, one that actually tests their products before they leave their website/store. I'd go with the following if I were you however note that I have never used 5.8Ghz myself but I understand the theory extremely well as I was a radar technician in the Navy on submarines and I did some radioman work and so on and I'm well versed in radio wave propagation etc etc etc.

Check out this page here, take note on how small the antennas are. http://www.readymaderc.com/store/index.php?main_page=index&cPath=11_30_33
 

R

RuralFPV

COWS!!!!
While 1G2/1G3 sounds like a panacea, be aware that it's first harmonic falls almost right on top of your 2G4 control signal. Many people have problems with that and will use UHF control.

Oh, 1000mW on 5.8G is a waste of money. You aren't going to get that far anyway as the signal at 5.8G acts more like light than RF... you can't shine a flashlight through a building.
 

H

helloman1976

Ziptie Relocation Expert
While that is possible with a cheap transmitter what you would due is put a filter on your transmitter which would filter those harmonics out. You are going to run into harmonics no matter what you do and going to UHF and running 1.3Ghz is no different as 433Mhz will produce harmonics on 1299Mhz so the problem is the same if not worse. You are further away from 2.4Ghz if you use 1.3Ghz video as in harmonics on 2.6Ghz which is 200Mhz off versus 1 Mhz with UHF.

Note that 1.3Ghz is not really 1.3Ghz, there are a couple channels to choose from on 1.3Ghz transmitters, they are 1280Mhz and 1258Mhz so you shouldn't have any issues with 2.4Ghz transmitters but you may if you go to UHF. If you do have an issue with your 2.4Ghz transmitter you'd put one of these on your 1.3Ghz transmitter, http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=165_108&products_id=1206 and problem solved.

While you cannot shine a flashlight though a building that analogy is far from radio transmission so it's not accurate at all. You can penetrate a building with radio if you have a strong enough and low enough signal just like you can hear bass from someone's car in your house but you can't shine your flashlight through it.
 


SMP

SMP

Member
Dunno, but I use notch filters on my 1.3 stuff and have never had to post a flyaway thread...
 

H

helloman1976

Ziptie Relocation Expert
baker55 said:
Would the notch filter be better than the low pass filter?
Click to expand...

Baker55 Notch filters are much better in this case as low pass filters attenuate the signal and can reduce the distance your signal will transmit as well as the quality by reducing the dB gain. Notch filters are the way to go and it's my personal opinion that you should use them whenever you can even if you don't "see" an issue. The further out you get the more a small issue because a big issue no matter how small that issue is.
 

B

baker55

Member
thanks, I think I will try one. On another note, since I dropped my vuzix glasses and had to replace with fatshark, I'm just not happy with the quality of return images. When I look through the monitor its a fairly good picture but with the fatsharks I have to say I am very disappointed! I bought the basic model because that is all that was available, but now that I have them I should have waited.
 

Bowley

Bowley

Member
Just signed on to start a new thread, but noticed this one running,
My question is about matching or mixing of Tx and Rx antenna. should you always use skew planar with clover leaf etc or is it OK to use a Rx patch panel antenna to get more range out of low powered Tx.
I want to limit myself to 25mW to stay legal, so was looking for some opinions on what the best antenna setup is.
Sorry to hijack your thread Teco, but thought this may be of interest to you also.

Steve
 


Hartz

Hartz

Herpaderpinator
Bowley said:
Just signed on to start a new thread, but noticed this one running,
My question is about matching or mixing of Tx and Rx antenna. should you always use skew planar with clover leaf etc or is it OK to use a Rx patch panel antenna to get more range out of low powered Tx.
I want to limit myself to 25mW to stay legal, so was looking for some opinions on what the best antenna setup is.
Sorry to hijack your thread Teco, but thought this may be of interest to you also.

Steve
Click to expand...

Steve my understanding is that you must use the same antenna. If you are using something like a skew planar you must even have the wire in the same orientatation. This is why we have left and right angle antennas.
 

H

helloman1976

Ziptie Relocation Expert
Bowley said:
Just signed on to start a new thread, but noticed this one running,
My question is about matching or mixing of Tx and Rx antenna. should you always use skew planar with clover leaf etc or is it OK to use a Rx patch panel antenna to get more range out of low powered Tx.
I want to limit myself to 25mW to stay legal, so was looking for some opinions on what the best antenna setup is.
Sorry to hijack your thread Teco, but thought this may be of interest to you also.

Steve
Click to expand...

You can mix and match antennas as long as they are polarized the same and are the same frequency. I use a linear whip antenna with a patch antenna on 900Mhz each. Many people use skewer planar wheels with patch antennas. If your skewer planar antenna is right hand circular polarized then make sure your patch antenna is right hand circular polarized as well.

As long as we are giving our opinions, forget going legal and blast away. I use 900Mhz at 1500mW all day everywhere I go but that's just my 2 cents. :D
 


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