Can a TV antenna pick up cosmic radio waves? - SETI Style Distributed Radio Telescope (DRT), is it p

BoJangles · Jul 6, 2008

My question is specifically related to the capability of an average TV antenna, on an average roof top, in an average configuration, to pick up non terrestrial radio waves.Now I realise TV antennas are directional and they are optimised for things like sex and the city coming from your local radio tower. But what I specifically want to know is, assuming you could “magically” remove the interference from terrestrial radio sources, could that aerial be used to pick up cosmic radio frequencies.I’ll put some constraints on this question, which are as follows;  we are using an average TV antenna, it is connected to coaxial cable (like most TV antennas), I have magic that can remove “all” terrestrial interference(or we lived in a radio dead world), I have a $1000 budget to buy and build amplifiers and the appropriate electronics to connect my antenna to my computer, I do not need any triangulation or directional information in regards to the frequencies (just a graph).I would assume if any signal could be picked up it would be very faint ( due to the configuration and design of the average TV antenna), but all I really want to know is the capability of a normal TV antenna in a normal configuration to receive the right frequencies needed to listen to things from outside the earth.Answers I would expect to get are. TV antennas cannot pick up the right frequency range (they just can’t), or the atmosphere would kill any chance of using a TV antenna in that way. Or sure you could probably pick up the right frequencies but they would be so small your $1000 budget would have no chance of enhancing them enough for useful science. Or sure that sounds possible but you would definitely need a radio dead world or magic to cancel out interference.Thanks for any response in advance---- Basic ideaBy tapping into the world’s computers and idle TV antennas with a small amount of inexpensive hardware and isolating specific frequencies of interest, we should be able to connect computers and TV antennas to create the world’s largest telescope. Sound crazy? Well it is.Some of the base principles are as follows.<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Base Stations</h3></li></ul>Base stations would be just normal households with a TV antenna and a very small and inexpensive piece of hardware that can connect a TV antenna to a computer (combined with software). There will potentially be 2 ways to acquire the hardware, a build yourself kit, and a commercial not for profit product that can be shipped anywhere in the world. <ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Calculation nodes</h3></li></ul>If people don’t want to participate in the physical telescope they can always just download the software and become an idle calculation node. There will need to be a lot of these for obvious reasons.<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Command and control centre</h3></li></ul>This is for distributing the appropriate information for this to all work. Middleware could be written to look at particular science questions. i.e. workloads could be shipped out to the network to ask specific question for science, one day the foundation / trust might harness the network to look at one problem, the next, a new work load could be distributed and optimised for another adventure. <ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">The distributed network</h3></li></ul>This software would be developed and optimised in such away to distribute middleware (changeable /scriptable workloads). It would be a platform designed with distributed mathematics in mind and customisable by the command and control server. Why stop at radio astronomy? (Basically this network would just act as a dedicated calculator and could be used as such to solve many problems). This would have the potential to be the world’s largest supercomputer. Obviously there will be limitations imposed by the distributed nature of such a network including lag and limited data throughput from node to node, but anything is possible.Fundamental problems<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">The TV antenna</h3></li></ul>These things are obviously not built for radio astronomy, but they are an antenna all the same, surely something useful could come from them (that doesn’t involve sex and the city). Additionally I'm not sure what useful frequencies these things could listen to in our terrestrial environment, but I'm sure there must be something.<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">The hardware</h3></li></ul>Obviously the hardware to connect the antenna to the computer is a large problem. The right electronics here will be essential for both the quality of data and the ease of construction. The idea would be to sacrifice the quality of the device, for the ease of assembly to make the array as large as possible.Ideally this device would be fairly cheap and could be a DIY kit. If this was not possible, kits could be sold. The goal is to get as many of these things around the world as possible, as cheap as possible, to create the largest array as possible.<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Synchronization</h3></li></ul>First real problem would be to get the entire antenna array synchronized. I propose using a combination of time servers and cosmological radio sources, random or otherwise, to stitch the network together and synchronise base stations. I.e. by allowing base stations to communicate with each other and knowing there geographical location, while comparing and masking data we should be able to triangulate and calibrate the antennae and software to a very precise synchronous array.<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Source triangulation</h3></li></ul>By knowing a base stations geographical location , altitude and taking into consideration atmospheric impedance as derived from the angle of observation , it should be possible to triangulate radio sources removing the need for a directional telescope (it’s just more maths).<ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Terrestrial interference</h3></li></ul>All though this seems like an insurmountable problem, by using calculations nodes to mask and compare datasets, a crystal clear image shouldn’t be such a problem. The more base stations, the more calculation nodes, the more we can play off base stations against each other and the better the resulting science will be. There are many examples of how this sort of technology works in the real world, even if 99% of the data each base station produced were noise, by cross referencing, the useful information will start to add up. <ul><li><h3 style="margin-top:10pt;margin-left:10pt;margin-right:10pt">Distributed Calculation Platform</h3></li></ul>This platform would have to be capable of communicating not only with the main server/s but to communicate with other nodes. There are several advantages to this, firstly being able to calibrate the array without massive server load, also if base stations were are able to connect to other nodes (like a buddy system), cross referencing to eliminate all interference should essentially be easy. Additionally being able to dump large workloads on to calculation nodes should greatly enhance the capabilities and speed.Obviously with all these calculations and the massive amounts of data obtained there will be lag (seconds, minutes, hours, days, months). No one would expect this to work in real time.There is a lot more to thisIt is obvious I have left out a lot of information and associated problems out of this Post; additionally my lack of understanding with radio astronomy probably sticks out like a gamma ray burst. But what I do know is the nearly unlimited power of distributed computing and there is a radio receiver on just about every roof in the world, those resources, if harnessed properly could /should achieve all that I imagine and more. <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

MeteorWayne · Jul 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>.Answers I would expect to get are. TV antennas cannot pick up the right frequency range (they just can’t), or the atmosphere would kill any chance of using a TV antenna in that way. Or sure you could probably pick up the right frequencies but they would be so small your $1000 budget would have no chance of enhancing them enough for useful science. Or sure that sounds possible but you would definitely need a radio dead world or magic to cancel out interference.Thanks for any response in advance  Posted by Manwh0re</DIV> I think the answers you expect to get pretty much sum the whole thing up. Don't think there's too much I could add. Even if you increased you budget by a factor of 10,000 I think you would still fall short. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

BoJangles · Jul 6, 2008

The reason I ask, is because, if you could combine 1000’s of TV antennas with a distributed computing power of likeminded people on the internet, triangulation gained from knowing the elevation and location of each antenna, and maths to remove interference from terrestrial interference, you could have the world’s largest radio telescope, it would just come down to the ability of a TV antenna to pick up the even smallest useable frequency and the budget to build an amplifier capable of enhancing the right frequencies. as allways thanks for your response <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

derekmcd · Jul 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I think the answers you expect to get pretty much sum the whole thing up. Don't think there's too much I could add. Even if you increased you budget by a factor of 10,000 I think you would still fall short. Posted by MeteorWayne</DIV>I guess it depends on what type of signals are being looked for.  If we're talking about turning your antenna into a SETI station... I'd agree.  Not possible.But your antenna is always picking up interference from the Sun and the CMB.  Turn your tv to a channel with no station and you can see this signal in the static.  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

BoJangles · Jul 6, 2008

Hrm interesting all the same, when we talk interference from the sun and CMB, I wonder if useful information could be gleaned from that with such a distributed array <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

MeteorWayne · Jul 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>The reason I ask, is because, if you could combine 1000’s of TV antennas with a distributed computing power of likeminded people on the internet, triangulation gained from knowing the elevation and location of each antenna, and maths to remove interference from terrestrial interference, you could have the world’s largest radio telescope, it would just come down to the ability of a TV antenna to pick up the even smallest useable frequency and the budget to build an amplifier capable of enhancing the right frequencies. as allways thanks for your response Posted by Manwh0re</DIV> Actually, that is exactly the concept behind a project underway. It could be the SKA (Square Kilometer Array) or one of the other large scale projects.See http://en.wikipedia.org/wiki/Square_Kilometre_Array <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

derekmcd · Jul 6, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hrm interesting all the same, when we talk interference from the sun and CMB, I wonder if useful information could be gleaned from that with such a distributed array Posted by Manwh0re</DIV>You might thinking about the Very Large Array in New Mexico?  Not precisely sure how all that works, but I doubt a bunch of TV antennae would increase your resolution much.  I honestly don't know.  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

BoJangles · Jul 6, 2008

It just seems a waste that all these TV antennas are being used on sex and the city (hundreds and hundreds of thousands of them) additionally with the internet we have the world’s largest computer (both are being under used). Surely there is something these things can be combined for. It’s a very seductive thought <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

MeteorWayne · Jul 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>It just seems a waste that all these TV antennas are being used on sex and the city (hundreds and hundreds of thousands of them) additionally with the internet we have the world’s largest computer (both are being under used). Surely there is something these things can be combined for. It’s a very seductive thought Posted by Manwh0re</DIV> The biggest problem is that TV antennas are picking up TV, particularly the VHF TV channels (2-13). While they soon will be shut down, that bandwidth is being sold to various other users so will be just as noisy in the future.That's why most Radiotelecopes are in remote areas, away from broadcast transmitters. Where I live, every channel from 2 to 13 is in use. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

BoJangles · Jul 7, 2008

As with adaptive optics and other systems that minimise noise by masking, if TV antennas could only pick up the smallest useful frequency, it would be worth while <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

MeteorWayne · Jul 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>As with adaptive optics and other systems that minimise noise by masking, if TV antennas could only pick up the smallest useful frequency, it would be worth while Posted by Manwh0re</DIV> Adaptive optics is a bad analogy. It is used to impove focus.Trying to use TV antennas for collection here would be like trying to use a telescope in NY City's Times Square.The only things you can see there are the moon, 3 planets, and 4 stars. I know, I've done the experiment

<div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

BoJangles · Jul 7, 2008

I appreciate your incite. And I am far from any expert in this field. But surely there must be something useful that can be massaged from such an array ( please read back ). Imagine 100,000 worldwide bits of metal connected to a computer connected to the world’s largest calculator. The resources we are talking about are massive, even if it only worked on the sun, CMB, or for atmospheric meteors, there must be something….Please believe me I am not trying to find an argument, just trying to find answers.Thanks for your time and I look forward to your response. <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

BrianSlee · Jul 7, 2008

Most TV antennas are tuned to be most effective at certain frequency ranges.  This is accomplished by matching the lengths of the receiving elements to some fraction of the wave length of the RF radiation you want to receive(if you look at the specs they might reveal the fraction i.e. 1/2 wavelength, 1/4 wavelength etc..).  I believe there is still quite a bit of signal activity in these ranges for your purposes.  I think what you are talking about might be possible with a decent spectrum analyzer and some software to interpolate the raw signals from all of the stations.  Not sure on the cost of the analyzer but I believe their are lots of choices that include a digital output.  Software might be alittle more problematic.  You might be able to adapt some existing programs or applications developed for the bigger systems if you could get your hands on the code. <div class="Discussion_UserSignature"> "I am therefore I think" "The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee </div>

BoJangles · Jul 7, 2008

Great! That’s the most positive thing I’ve heard to date. The software side of things, well that’s the easy bit in the scheme of things (software is just hard work, and with ‘open source projects’&hellip

, the physics on the other hand is the hard bit. If it can’t be done, it can’t be done. <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

BrianSlee · Jul 7, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Great! That’s the most positive thing I’ve heard to date. The software side of things, well that’s the easy bit in the scheme of things (software is just hard work, and with ‘open source projects’&hellip

, the physics on the other hand is the hard bit. If it can’t be done, it can’t be done. Posted by Manwh0re</DIV>You might also be able to use the radio transmissions from an atomic clock (or maybe GPS signals) as a calibrated time source for interpolation. <div class="Discussion_UserSignature"> "I am therefore I think" "The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee </div>

Mee_n_Mac · Jul 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>You might also be able to use the radio transmissions from an atomic clock (or maybe GPS signals) as a calibrated time source for interpolation. Posted by BrianSlee</DIV> The above point is a good one.  Let's pretend that the frequency range TV antennae can receive is of some use and is free of terrestrial interference.  Having 1000's of little antennae is better than having just 1 such small antenna but once you've ganged 30 or 40 of them together you've got all the increase in detection probability that you're going to get.  You'd still not match a single big antenna with a dedicated low noise receiver IMO.  Having the TV antenna/receivers spread far apart could give you better angular resolution but only if you have some way to have them all referenced to a common time source.  Hard to create a big phased array when you can't get the elements phased. I have to believe the modern radio observatories have just such a method because I know they have used antennae in different countries in some kind of VLBI arrangement to get higher resolution maps of astronomical objects. I don't know what they did to achieve this. <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

MeteorWayne · Jul 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>The above point is a good one.  Let's pretend that the frequency range TV antennae can receive is of some use and is free of terrestrial interference.  Having 1000's of little antennae is better than having just 1 such small antenna but once you've ganged 30 or 40 of them together you've got all the increase in detection probability that you're going to get.  Posted by mee_n_mac</DIV> That's the tough part. At TV antenna frequencies. there are only a handful of places where it is free from tereestrial interference. Any places where you receive TV signals with the device are almost by definition disqualified as a clean or useful source. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

BrianSlee · Jul 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>That's the tough part. At TV antenna frequencies. there are only a handful of places where it is free from tereestrial interference. Any places where you receive TV signals with the device are almost by definition disqualified as a clean or useful source. Posted by MeteorWayne</DIV> I don't think that this solution will ever replace large parabolic dishes with expensive LNB hardware but I think some basic functionality could be realised by aspiring radio-astronomers.  Probably would be better to go find an old parabolic dish with a cheap LNB and use that instead of a tv antenna.  I don't know if the LNBs for older satelite dishes would be useable though for this purpose. <div class="Discussion_UserSignature"> "I am therefore I think" "The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee </div>

bdewoody · Jul 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>My question is specifically related to the capability of an average TV antenna, on an average roof top, in an average configuration, to pick up non terrestrial radio waves.Now I realise TV antennas are directional and they are optimised for things like sex and the city coming from your local radio tower. But what I specifically want to know is, assuming you could “magically” remove the interference from terrestrial radio sources, could that aerial be used to pick up cosmic radio frequencies.I’ll put some constraints on this question, which are as follows;  we are using an average TV antenna, it is connected to coaxial cable (like most TV antennas), I have magic that can remove “all” terrestrial interference(or we lived in a radio dead world), I have a $1000 budget to buy and build amplifiers and the appropriate electronics to connect my antenna to my computer, I do not need any triangulation or directional information in regards to the frequencies (just a graph).I would assume if any signal could be picked up it would be very faint ( due to the configuration and design of the average TV antenna), but all I really want to know is the capability of a normal TV antenna in a normal configuration to receive the right frequencies needed to listen to things from outside the earth.Answers I would expect to get are. TV antennas cannot pick up the right frequency range (they just can’t), or the atmosphere would kill any chance of using a TV antenna in that way. Or sure you could probably pick up the right frequencies but they would be so small your $1000 budget would have no chance of enhancing them enough for useful science. Or sure that sounds possible but you would definitely need a radio dead world or magic to cancel out interference.Thanks for any response in advance  Posted by Manwh0re</DIV>We are talking about satellite dishes and not the old things we had on our roof's 30 years ago aren't we. <div class="Discussion_UserSignature"> Bob DeWoody </div>

BrianSlee · Jul 9, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>We are talking about satellite dishes and not the old things we had on our roof's 30 years ago aren't we. Posted by bdewoody</DIV> My previous answeres were based on simple dipole antenna arrangements. <div class="Discussion_UserSignature"> "I am therefore I think" "The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee </div>

BoJangles · Jul 9, 2008

This Post has been moved to the topic.  <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

BoJangles · Jul 9, 2008

There is no doubt (even without the radio astronomy part) there would be a considerable amount of merit in such a large calculator. I propose this could be a ”limited open source project” (limited in respect to we don’t want people to run off with the code, but to help develop the project to fruition). All the code would belong to the foundation / trust (whatever).Additionally there is more money than brains floating around the world, Google has more money than they deserve, and people get grants for much less, raising money with the right academic help and or public support shouldn’t be a problem, if only people were to believe in the dream (assuming this is all possible from a mathematics and EM point of view).My question to the reader is can you help? Do you think this idea has merit? Can you see any problems? can you contribute anything to this (every word will be more than greatly appreciated).I realise, about now, you all think im a crack pot, but this is why i am here, to work through the problems, to work out if this would be feasable. if its not possible its not possible.Note: This all might be better under a new thread and topic   <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

skeptic · Jul 9, 2008

I'm not a radio astronomer but I am an RF engineer and I think I can partially answer your question.  One problem is that cosmic electromagnetic radiation isn't evenly spread across the spectrum so the VHF and UHF antennas may not do any good if there isn't much radiation at those frequencies.  Jupiter for instance radiates at between 5 and 40 MHz with peaks at 18 and 24 MHz.  Best times are between 9:00 PM and dawn.  Use a good shortwave receiver and a simple dipole for 18 to 24 MHz oriented east-west.  The signal sounds like rising and falling swooshing sounds.I'm told the first person to detect a pulsar was a female graduate student who didn't have money for time on a radio telescope.  She constructed hundreds of dipoles that covered about an acre and was able to focus them by electronically adjusting their phase. If you're serious you should pick up some books about antennas and radio astronomy.  I referenced Practical Antenna Handbook by Joseph Carr for this post.

BoJangles · Jul 9, 2008

Great thanks, I know I'm well and truly out of my league when it comes to this stuff, but I plod away all the same. My main concern is the ability of antenna to pick up frequency ranges, ie I'm sure a tv antenna ( not to mention the technology I propose) has some sort of limits on min and max frequency it could theoretically deal with, I'm just quietly hoping that it has a broad enough range to make it useful.   <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

BrianSlee · Jul 10, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Great thanks, I know I'm well and truly out of my league when it comes to this stuff, but I plod away all the same. My main concern is the ability of antenna to pick up frequency ranges, ie I'm sure a tv antenna ( not to mention the technology I propose) has some sort of limits on min and max frequency it could theoretically deal with, I'm just quietly hoping that it has a broad enough range to make it useful.   Posted by Manwh0re</DIV>Here is your frequency chart**from Wikpedia**<h3>[edit] North and South America (most countries), South Korea, Taiwan and the Philippines</h3><dl><dd><div class="noprint relarticle mainarticle">Main article: North American broadcast television frequencies</div></dd></dl>Channel 1 was finally withdrawn on 14 June 1948 and allocated to fixed and mobile services. In some countries using the standard, channels 5 and 6 are allocated to non-broadcast services. An international agreement provides for a unified television bandplan, with 6-MHz channels throughout ITU Region II for both VHF and UHF bands, except for French territories, Falkland Islands, Greenland and Netherlands Antilles. Not all territories observe this bandplan.During World War II the frequencies originally assigned to channels 13 to 18 were appropriated by the military, which still uses them. It was also decided to move the allocation for FM radio from the 42-50 MHz band to a larger 88-106 MHz band (later extended to the current 88-108 MHz FM band). This required a reassignment of the VHF channels to the plan currently in use. [1]<a id="Assignments_since_25_February_1946" name="Assignments_since_25_February_1946" title="Assignments_since_25_February_1946"></a><h4>[edit] Assignments since 25 February 1946</h4><table border="1" class="toccolours" style="border-collapse:collapse;text-align:center"><caption>System M 525 lines (most countries in the Americas and Caribbean, South Korea and the Philippines) System N 625 lines (used in some South American Countries) VHF low-band (band I) </caption><tbody><tr><th>Channel</th><th>Lower edge</th><th>Video carrier</th><th>DTV carrier</th><th>Audio carrier</th><th>Upper edge</th></tr><tr><td>1*

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