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How to transmit composite video

by Tesladude
Tags: composite, transmit, video
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Tesladude
#1
Jul18-14, 02:52 AM
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Can I use a 315MHz transmitter module to send a composite video signal to another reciever module?
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Baluncore
#2
Jul18-14, 04:43 PM
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Bandwidth of a 315 MHz module is probably too narrow for video signals.
315 MHz is usually used for lower data rate digital links.
davenn
#3
Jul19-14, 02:42 AM
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HI Tesladude

I dint know if you realise but there are dozens of AV sender and receiver modules out there
that a licence isn't required for ... here's one eBay example.....
http://www.ebay.com.au/itm/like/1213...=true&lpid=107


That one is 200mW quite high power. I don't know what country you are in or what the legal power limits are before a licence would be needed.

A composite video signal requires approx. 7MHz bandwidth

I would strongly suggest you experiment with these styles of modules as you really don't want to
be playing with RF electronics unless you have the skills and test equipment

cheers
Dave

sophiecentaur
#4
Jul19-14, 07:01 AM
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How to transmit composite video

Quote Quote by Baluncore View Post
Bandwidth of a 315 MHz module is probably too narrow for video signals.
315 MHz is usually used for lower data rate digital links.
PAL and NTSC get away with about 7MHz.
Baluncore
#5
Jul19-14, 09:04 AM
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Quote Quote by sophiecentaur
PAL and NTSC get away with about 7MHz.
Which is the problem. The SAW filters used in 315MHz modules are usually only 600 kHz wide.

http://www.maximintegrated.com/en/ap...ex.mvp/id/3587
Quote Quote by Extract from Maxim APPLICATION NOTE 3587
FCC Section 15.231(c) states that the emission bandwidth of the intentional transmission shall be no wider than 0.25% of the center frequency, where the emission bandwidth is determined by the points in the radiated spectrum that are 20dB below the modulated carrier. For 315MHz and 433.92MHz, the two most-used frequencies in the 260MHz to 470MHz unlicensed band, the maximum allowable bandwidths are 787.5kHz (394kHz) and 1.085MHz (542kHz).
sophiecentaur
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Jul19-14, 06:18 PM
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Quote Quote by Baluncore View Post
Which is the problem. The SAW filters used in 315MHz modules are usually only 600 kHz wide.

http://www.maximintegrated.com/en/ap...ex.mvp/id/3587
600kHz is too narrow but what about the units suggested by Davenn? They claim to be AV capacity.
Baluncore
#7
Jul19-14, 09:09 PM
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Quote Quote by sophiecentaur
They claim to be AV capacity.
Then they fail to meet the FCC specifications in USA where 315 MHz 394kHz is available for compliant devices.

Digital FSK has some immunity to interference, analogue ASK does not.
On 315 MHz the AV would be sensitive to interference from many compliant devices.

Chinese manufacturers are now flooding the world market with non-compliant broadband products.
There are frequency allocations available for AV distribution in the USA that are more appropriate than 315 MHz.
I don't think PF should encourage anarchy in the spectrum.
jim hardy
#8
Jul19-14, 10:41 PM
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The units Dave linked appear to be not 315 mhz but 5.8ghz

any relief there ?
davenn
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Jul19-14, 11:19 PM
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yeah that was on purpose, Jim
was trying to get Tesladude as far away as possible from the 315 and 433MHz bands

mainly cuz of the masses of available 2.4 and 5.8 GHz AV senders and receivers available at small prices :)

Dave
Baluncore
#10
Jul19-14, 11:50 PM
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Sorry, I missed that link.
Quote Quote by Tesladude, in the OP
Can I use a 315MHz transmitter module to send a composite video signal to another reciever module?
The answer is NO. Do not use 315 MHz or 433 MHz for video.
As others have pointed out, there are better bands allocated for short range video transmission.

Quote Quote by davenn
was trying to get Tesladude as far away as possible from the 315 and 433MHz bands
That is very wise.
sophiecentaur
#11
Jul20-14, 05:21 AM
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Quote Quote by Baluncore View Post
T

I don't think PF should encourage anarchy in the spectrum.
Absolutely; I couldn't agree more. Things are getting slacker and slacker as it is.
Tesladude
#12
Jul22-14, 10:37 PM
P: 135
i know im a little late with my response because guess my mind had responded and not my hands, those modules suggested seem totally reasonable and I will be purchasing them soon!


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