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Apr 04, 2016, 04:36 AM
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Thread OP
Discussion

Why we cannot use old analog TV frequency for FPV video link ?


Hello,

With the full migration from analog TV over the word, there is a lot of interesting frequency that are free.
We dont care about HD, so we can use them for FPV ? (maybe only for radio amateur)

The frequency are a lot lower, the range should be a lot better.


Can you tell me why there is nothing about this ?
Julien
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Apr 04, 2016, 05:40 AM
A man with too many toys
That’s a good question. I wonder what happened to all those old VHF frequencies.
https://en.wikipedia.org/wiki/North_...on_frequencies


.
Apr 04, 2016, 05:53 AM
Registered User
Thread OP
I also cant understand why people said that with video link at 1.2 Ghz you have a lower quality than 5.8Ghz, because the old analog TV frequency was a lot lower !! 54 mhz for band 1 ! And the quality was OK

For the use of this kind of frequency I think the problem is juste the size of the antenna, it would be really big for a 250 mini quad !
Apr 04, 2016, 10:19 AM
Team AlienWarpSquad
Quote:
Originally Posted by jujun
I also cant understand why people said that with video link at 1.2 Ghz you have a lower quality than 5.8Ghz, because the old analog TV frequency was a lot lower !! 54 mhz for band 1 ! And the quality was OK

For the use of this kind of frequency I think the problem is juste the size of the antenna, it would be really big for a 250 mini quad !
54 mhz = 54 milli Hertz!!!
Do you really mean 54 MHz (Mega Hertz)?

Might also be that 1.2GHz vTXs are just of poor quality and has nothing to do with the frequency.
Apr 04, 2016, 10:42 AM
Registered User
Thread OP
Quote:
Originally Posted by waltr
Do you really mean 54 MHz (Mega Hertz)?
Yes, Mhz, sorry.
Apr 04, 2016, 01:06 PM
A man with too many toys
Quote:
Originally Posted by jujun
I also cant understand why people said that with video link at 1.2 Ghz you have a lower quality than 5.8Ghz, because the old analog TV frequency was a lot lower !! 54 mhz for band 1 ! And the quality was OK

For the use of this kind of frequency I think the problem is just the size of the antenna, it would be really big for a 250 mini quad !

I fly some 1.2 and the problem is there is not a good selection of good quality transmitters, they are all very old designs. The other problem with 1.2 is there are only two US legal channels. On the other hand 5.8 is very popular so many companies are making new high quality equipment.

If come company would start making high quality for FPV equipment for the old TV bands they would be popular for long range FPV.

BTW for those lower frequencies you donít need CP antennas because multipath is not a problem. You can just use a simple linear antenna.


.
Apr 04, 2016, 09:20 PM
Long Range FPV addict
For a start I doubt the Governments will give up those frequencies for anything non commercial. They are in the PRIME frequency range in my opinion.

But the thing you are missing is bandwidth. On 5.8ghz the bandwidth is greater per channel than on 1.2ghz hence the slightly degraded color/quality of the signal.

The lower you go in frequency the bandwidth eats up a lot of the frequency allocation.
Apr 04, 2016, 10:06 PM
Registered User
Daemon's Avatar
The analog channel usage of that frequency band is gone, but the frequencies are still in
used by digital TV. It's just a little confusing because the digital TV channel #s often have
nothing to do with the particular frequency range. Old analog Ch7 frequencies might be used
by new DTV ch2, and so orth. And there actually already exists a couple amateur TV frequencies in this
band (have always been there). They're just not popular because the antennas are huge
and the VTX/VRX gear is all ancient, and often hand build by hams.
Apr 06, 2016, 02:11 AM
Registered User
Quote:
Originally Posted by jujun
Hello,

With the full migration from analog TV over the word, there is a lot of interesting frequency that are free.
We dont care about HD, so we can use them for FPV ? (maybe only for radio amateur)

The frequency are a lot lower, the range should be a lot better.


Can you tell me why there is nothing about this ?
Julien
The existing FPV equipment runs in amateur radio TV bands because that is what it is based on. Many of those flying FPV are doing so illegally because they do not have the required license for the gear they are using.

Most of the analog TV frequencies are being used by digital TV and other services. They are not free. Radio spectrum is a limited resource that governments sell access to or provide conditional access to.

For example, the Australian government sold of the 700MHz segment that was once used for TV, and some of the 2.5GHz range, to be used for 4G/LTE services. That brought in slightly less than A$2B. I'm sure a similar sale in the US what make many times that amount.

http://www.acma.gov.au/Industry/Spec...uction-results
Apr 06, 2016, 07:29 PM
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v2rocketeer's Avatar
Quote:
Originally Posted by Robert_AU
Most of the analog TV frequencies are being used by digital TV and other services. They are not free. Radio spectrum is a limited resource that governments sell access to or provide conditional access to.

For example, the Australian government sold of the 700MHz segment that was once used for TV, and some of the 2.5GHz range, to be used for 4G/LTE services. That brought in slightly less than A$2B. I'm sure a similar sale in the US what make many times that amount.

http://www.acma.gov.au/Industry/Spec...uction-results
Well said mate,

Which is why people who fly fpv should get the appropriate Ham license for their country. The radio spectrum we use has an awful lot of value to companies and spectrum is limited. There are nice portions of the rf spectrum put aside by most governments of the world for ham radio operators to use. If people bootleg it and fly fpv without a lic they may never get caught but more importantly they will never be counted as a legal user. We need to increase the number of hams there are using these frequencies to keep the governments from selling them.

Bear
Apr 07, 2016, 05:22 AM
A man with too many toys
Is their such a thing as an International Ham license so I can fly in any country when I travel?
Apr 07, 2016, 08:55 AM
Team AlienWarpSquad
Quote:
Originally Posted by RC Man
Is their such a thing as an International Ham license so I can fly in any country when I travel?
There are Reciprocal agreements among many countries that allow say a US license to be used in Germany or the UK.
Some of these are automatic others require the licensee to obtain permission.

http://www.arrl.org/reciprocal-permit-faqs
Apr 07, 2016, 11:29 AM
400' + is where fun starts.
Martin Y's Avatar
For my first set-up I used UHF ch14 (470 mhz)for video tx. There was nothing around untill you got to ch17 and that TV station was 90 miles away.


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