Transmission of video signals

[sri_reddy523]

`i want to transmit video signal output from camera. so i want to transmit the signal for a distance of 1km range. so which modulation is preferrable. also give me complete details on the above thread.

 

[Nigel Goodwin]

It's complicated, it's expensive, and it's almost certainly illegal - depending where you live you may be able to buy video senders?, but they don't have anything like that range.

 

[j.p.bill]

First pick a frequency, and then see if Uncle Charlie (the FCC) wants you to ship video over the airwaves at that spot. If you can find a freq, look at the way moden broadcast tv is transmitted - that's also video.

 

[RadioRon]

`i want to transmit video signal output from camera. so i want to transmit the signal for a distance of 1km range. so which modulation is preferrable. also give me complete details on the above thread.

FM is the preferred modulation but will require you to design a transmitter and receiver. AM is used in regular televisions so if you use a TV set as a receiver, you only need to build a transmitter. If you want to use the transmitter soon, there are many many products available to do this using FM to a range of about 100m that operate in the 2.4GHz band. Google search for "video transmitter receiver" for some examples. Most provide a good quality picture and sound but will be very difficult to get 1Km range.

If you want the experience of designing and building it yourself, beware that it is not easy. Complete details are impossible to give on a forum such as this, only a starting point for your own research can be suggested. Here is one:

https://www.google.ca/search?hl=en&q=video+transmitter+schematic&meta=

 

[ericgibbs]

hi sri,

In the UK, you can purchase, a legal A/V sender/receiver pair for around £40GBP, Freq 433mHz, [freeband] upto a range of 100mtr line of sight.

Some types will transmit/receive upto 1kmtr, line of sight, with a special dipole. [£100GBP. for the diploe]

They accept standard A/V Scart/phono signal levels and the receiver outputs A/V signals.

Not knowing where you are located, you should check which 'freebands' you are allocated.

EricG

 

[Blueteeth]

I blieve all UK video senders use either the 2.4Ghz or the 5.8Ghz bands. Eric, think you you made a boo-boo there, 433Mhz has very limited bandwidth an many restricitons . Can't see it carrying video legally.

The output of the standard senders (from memory) is limited to 10mW, thats about 100m line-of-sight, ideal conditions, and with standard antenna. For greater range, adding a RF amp is illegal (in the UK, and most countries) as most AV senders are already set to the maximum allowed output power. However, a directional antenna would get you your 1km, although both tx and rx locations would have to be fixed. Buy or build, theres loads of cheapo DIY antenna's on the web used for wifi, on the same band, so they should work just as well.

Wouldn't know about 'quality' of reception, I just use mine for data.

Blueteeth

ps. my knowledge of RF is extremely limited, I don't design em, I use em.

 

[Nigel Goodwin]

I blieve all UK video senders use either the 2.4Ghz or the 5.8Ghz bands. Eric, think you you made a boo-boo there, 433Mhz has very limited bandwidth an many restricitons . Can't see it carrying video legally.

You can do it as a radio ham - but it wouldn't make you very popular, as you take up all the 70cm band!

 

[Hero999]

Can you do it digitally using low resolution with compression?

 

[ericgibbs]

hi blueteeth,

Re-checked my latest [2007] product catalogs.
Says 433MHz A/V for a number of different manufacturers.

BUT, as we all know 'what the catalog claims' can be wrong.
I'll do some more checking. If I find its in error I'll let you know.

Regards
EricG

Update:
Scanned the web, 433MHz is a 'open frequency' also as you say, 2.4GHz
Lots of 433MHz A/V senders.

 

[JimB]

hi blueteeth,

Re-checked my latest [2007] product catalogs.
Says 433MHz A/V for a number of different manufacturers.

BUT, as we all know 'what the catalog claims' can be wrong.
I'll do some more checking. If I find its in error I'll let you know.

Regards
EricG

Update:
Scanned the web, 433MHz is a 'open frequency' also as you say, 2.4GHz
Lots of 433MHz A/V senders.

433Mhz is NOT an "open frequency" where any old rubbish can take place.
In the UK, the Primary User is the MOD, with Radio Amateurs allocated as a Secondary User.
There is a small band at 433.something for Low Power Short Range Devices.
Car remote keys, low power telemetry RF modules, things like that. These devices are supposed to be approved and tested.
It does not give carte blanche to someone who has not got a clue about RF to go building some piece of junk which splatters all over the RF spectrum.

JimB

 

[ericgibbs]

hi JimB,

Totally agree regarding the possible EMR pollution when using a 'home grown transmitter project', thats why I am suggesting to the OP, he buys an approved TXR link.

Ref the 'open' this is whats being stated on a number of reputable web sites. Perhaps we should challenge that claim?.

If he is in doubt he should consult the local authority regarding any restrictions, if he intends building this himself.

I don't know the country where the OP is based?

Regards
EricG

 

[Nigel Goodwin]

hi JimB,

Totally agree regarding the possible EMR pollution when using a 'home grown transmitter project', thats why I am suggesting to the OP, he buys an approved TXR link.

Ref the 'open' this is whats being stated on a number of reputable web sites. Perhaps we should challenge that claim?.

Just because they are advertised on the net doesn't mean they are legal to use!. All video senders were illegal in the UK, although I understand the 2.4GHz ones are now approved? - although don't work if you have wireless broadband!.

Quick edit:

I've just done a quick goggle, the video senders you're talking about are 2.4GHz - the 433MHz is for the REMOTE CONTROL - not the video.

 

[ericgibbs]

hi Team,

Had a more thorough look, Woops! you are correct.

Just goes to show, one's [hopefully] never to old to learn.

As they say ,when all else fails read the manual'.

Many thanks, Nigel, I hate to propagate mis-information.

I will now go and scourge myself with wet birch branches for 10 minutes!!!.

EricG

Hi JimB
15mins,,,, mmh
Problem is, I might get to like it!. I'll stick with 'horse hair' underwear for any future penance.
Thanks E

 

[JimB]

I will now go and scourge myself with wet birch branches for 10 minutes!!!.
EricG

Not enough! I insist that you do it for at least 15 minutes!

JimB

 

[Blueteeth]

The '433MHz' they quote IS used by many A/V senders, just not for the video/audio signal It's a utility RF link for carrying remote control signals from the Rx to Tx, so you can transmit the signal from a DVD player downstairs and still pause/ff/rw etc...

It is misleading, and it gets my blood up when I see 'Digital TV A/V sender!' when its just a standard analogue sender, but with a scart socket for the input, instead of RCA, and even then, scart is still analogue (despite a 12 minute argument with a bloke in Dixons, fool). Still, we're engineers here, we know different

To the OP, as I said before, a directional antenna would add a fair bit of gain, and I tihnk you may be able to add in an RF amp providing you don't go over the top, and that your antenna's are very direcitonal, I still say 2km is possible with these modules.

Try **broken link removed**

I have the smallers ones, but my app is portable.

Blueteeth

PS. just realised I repeated what nigel said, sorrry