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Rf frequency

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mpj111

New Member
Is it possible to convert RF signal(TV signal) transmit through cat6 or cat5 cable.
I heard there are conversion kits available to that then reverse itat the oyher end.
your healp much appreciated.
 

MikeMl

Well-Known Member
Most Helpful Member
Are you talking "over the air"TV (Chan 2 on up, >54Mhz), or are you talking video baseband bandwidth (< 5Mhz)?
 

ke5frf

New Member
What are you trying to do?

I don't care if it is possible or not, coax cable is the proper conductor for RF signals in terms of shielding and preventing electromagnetic interference both radiated and recieved, unless you are using balanced ladder line to an antenna or something (which is still debateable)

Now if you wanted to set up a simple wireless "cable wifi" in your home, hooking rabbit ears into a cable wall outlet will rebroadcast the cable to another room but thats technically wrong to do as well.
 

RadioRon

Well-Known Member
Is it possible to convert RF signal(TV signal) transmit through cat6 or cat5 cable.
I heard there are conversion kits available to that then reverse itat the oyher end.
your healp much appreciated.

Yes it is possible. The most common method would be to use industry standard methods to transport the signal digitally. Easiest way to do this would be to stream the data via ethernet (on CAT6 cable) between two computing devices. Here is some info:

How to Connect a PC to an LCD HDTV Via Ethernet | eHow.com
 

Sceadwian

Banned
ke5frf, you're saying that anyone that is using an 100 base TX ethernet card is using the wrong technology. Differential signaling over twisted pair transmitting lines works juuust fine. Must be doing something right if they can transmit a few hudred mhz signals over appreciable distances. Sending a baseband TV signal over twisted part cat5 is nothing new.
 
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ke5frf

New Member
ke5frf, you're saying that anyone that is using an 100 base TX ethernet card is using the wrong technology. Differential signaling over twisted pair transmitting lines works juuust fine. Must be doing something right if they can transmit a few hudred mhz signals over appreciable distances. Sending a baseband TV signal over twisted part cat5 is nothing new.


"sending a baseband TV signal over....yadda yadda"

Where did he mention baseband?
 

ke5frf

New Member
This is the first wiki paragraph (I know, wikipedia....) for baseband:

In telecommunications and signal processing, baseband is an adjective that describes signals and systems whose range of frequencies is measured from zero to a maximum bandwidth or highest signal frequency; it is sometimes used as a noun for a band of frequencies starting at zero. It can often be considered as synonym to lowpass, and antonym to passband, bandpass or radio frequency (RF) signal.

He clearly said RF. I answered the question as it was posed.
 

Sceadwian

Banned
Right about....
Is it possible to convert RF signal(TV signal) transmit through cat6 or cat5 cable.
I heard there are conversion kits available to that then reverse itat the oyher end.
your healp much appreciated.
There..

To convert an RF signal into a TV signal it has to be demodulated, so then you have a TV baseband signal, which he then wants to transmit through a cat5/6 cable. TV signals have a pretty large bandwidth that extends well into the RF range, but it is not typically speaking an RF signal. The primary consideration being that an 'RF' signal should be modulated by the baseband signal. It's a little open to interpretation in the ELF/VLF area as the signal being transmitted has a carrier frequency so low it can hardly be called modulated.


I would personally distinguish baseband from RF to mean that the baseband must have a lower bandwidth than the RF channel spacing.
 
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ke5frf

New Member
Transmitting radio frequency signals via non-shielded, non RF-designed transmission line is pooooor, in fact pi55555 poor engineering and is likely to have radio amateurs using triangulation techniques to find the source of interference on harmonics if they happen to fall on our bands. I'm just sayin'.
 

ke5frf

New Member
OK, you must be an engineer.
(kidding)

Point still stands, avoid RF signals on transmission lines it wasn't intended for.
Maybe his post was a little vague and open for interpretation, but making that point was worth my effort and bears repeating in the future :)

And I'm not sure that you are absolutely using the right terminology when you imply that a "TV signal" is demodulated TV baseband. I'm sure, as I reread his post, that this is what he meant, but before a TV signal is demodulated, it first must pass through an IF filter and THEN it becomes demodulated into audio and composite video...am I not correct? And I've never heard those called TV signals.
 
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Sceadwian

Banned
ke5frf this is why data lines for all modern digital transmission techniques use LVD signaling, the voltage is so low the outputted power even on high frequencies is incredibly low and even this doesn't occur because of the shielding. Signal cables in modern PC's and digital devices goes well into 100mhz bandwidth. Which unfortunately is also WELL inside the RF range for audio communication bellow the baseband, so it redefines gray area =) Missing or poor shielding can raise the noise floor big time for RF.
 
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ke5frf

New Member
Good point, and believe me I know how bad the noise floor is at times and Plasma TVs are another sore spot.

Like I said, avoid it, please. Even a poorly crimped or loose CATV connection can be a potential radiator and create havoc for licensed radio stations.

Contrary to popular belief, radio hobbyists still exist...perhaps not to the degree of the 50s and 60s "boom", but our numbers are plentiful enough to have reason to protect the radio spectrum. With proper technique there can be peaceful coexistance :)
 

Sceadwian

Banned
If the numbers are plentiful enough to protect the radio spectrum they're doing a piss poor job of it.
There's still a lot of broadband over power stuff going on, though that's hitting a lot of brick walls I think. And the subtle (but technically very large) increase in the noise floor on a lot of bands is a problem that really can't be addressed by any other means than educating people that are causing the problem in the first place.
 

ke5frf

New Member
Well, I know what you mean about BPL...and the ARRL is hunting that dog but I havn't kept up with the issues. I mentioned in another thread I've been "QRT" for a while know (newlywed with a baby)...so I let my ARRL membership and QST magazine subscription expire.

This is politics and clearly the radio spectrum is under pressure and competition. Fortunately HF frequencies aren't good for much more than casual hobbyist or emergency response use with satellites handling global communication infrastructure...so they are safe from encroachment in that respect. It is the UHF,VHF, SHF and microwave frequencies that we are doomed to eventually lose :( I imagine anyway.
 

Sceadwian

Banned
I'm sure there will always be available bands for amateur work, how usable they are is another story.

I only catch brief flashes of BPL off the net, I'm pretty sure it's doomed to failure, the infrastructure for proper transmission of high bandwidth data is already in place to all but the most isolated places, and the universal increase in the noise floor to those locations can't be justified by the population its serves. Satelite or directed line of site RF makes much more sense in those areas.

I'm just an observer from the outside but as far as the amateur radio spectrum goes I've always thought BPL was going to be the absolute dead end for <30mhz DX'ers, even at power. Broadband data looks just like noise to a receiver unless you have access to the data source, and if you do have access to the data source WTF are you using it for in the first place?! =P
 
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ke5frf

New Member
Good conversation and points.

The ironic thing about this is that much of the technology that BPL has its roots in was pioneered or heavily experimented with by radio amateurs in the 70s and 80s. I mean, much of the early technology and concepts that helped create the internet stemmed from packet radio and even radio teletype way back in the 40s and 50s..

I agree that there will always be legitimate spectrum for experimentation and recreational use, but the radio amateur hobby is very broad in scope and interests and certain bands are suitable for certain techniques while others are not, and the bands that are most at risk as far as the FCC reassigning them are the higher frequency bands that digital systems covet. A lot of commercial interests and big money salivating for more real estate. While I'm not a big user of those frequencies and never was except when I had only Technician privelages, I am all for protecting them. Actually, I take that back, one of my favorite bands is 6 meters (50Mhz) and it is just on the borderline of useability by localized commercial entities. It is the inbetween band because long distance communication is very sporadic (called sporadic E in fact) and instances of local users being interfered with by E signals is rare. But this is the fun of the band, I think. Many 6 meter enthusiasts literally sit near a computer and wait for spotters to announce an E opening when conditions are favorable. One old timey technique is to monitor broadcast television for ghost stations that pop up on locally unoccupied channels. I wonder if the end of analogue means that technique is nullified? I suppose it does because digital signals are either there or not, no snow.
 

Sceadwian

Banned
Actually you can get periodic interference on digital RF transmissions just the same as you can analog ones especially one way ones, the effects are much more like jumping off a cliff than a gradual loss in signal quality though. Really tiny glitches in digital transmissions can look like mpeg artifacts, aka the blockies, or other subtle either unnoticed or unobservable glitches in the converted data stream.
 
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