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Radio spectrum: a critical natural resource

Edward Campbell

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Part 1 - Background

tomahawk6 said:
UAV's, aircraft and communications have put a strain on available bw breaking this bottleneck is essential or it will limit the use of all these assets we are using to becoe "netcentric".

Army Times:
Breaking the bandwidth barrier

Army works to increase capacity for ever-expanding network
kosborn@militarytimes.com - kosborn@militarytimes.com
Posted : January 21, 2008

Within five years, the Army may have too little radio spectrum to allow its next-generation, networked force to work as it is being designed to work, the service’s outgoing procurement chief said.

Battlefield communications networks that allow friendly forces to exchange voice, data and video signals will be key to an Army equipped with 27-ton Future Combat Systems vehicles instead of 70-ton Abrams tanks. Even with Joint Tactical Radio Systems that move bits hundreds of times faster than earlier radios, the needs of an information-powered force are poised to overwhelm the available bandwidth.

“We have enough to do the job today, but I am not convinced we have enough to do the job I see coming five years from now,” said Claude Bolton, outgoing assistant Army secretary for acquisition, logistics and technology.

Beginning in 2010 and continuing for several decades, the Army will introduce elements of an ever-more-networked force that moves vast amounts of data from soldier-mounted sensors, aerial and ground robots, manned vehicles and more.

Bolton, who stepped down from his job Jan. 2, said the Army is taking several steps to head off a communications crunch.

First, he wants a better sense of the magnitude of the problem. In December, Bolton commissioned the California-based think tank RAND Corp. to estimate his service’s bandwidth needs in 2012, 2017, 2022 and 2027.

“I commissioned a study because I think it is time to get real data, at least for the Army, because I could not find a study in the Department of Defense that gave me a database estimate of bandwidth requirements over the next 20 years in five-year increments,” he said.

Bolton has asked the Army Science Board to look at the problem.

One area of promise is advances in compression technologies, which condense transmitted information to more efficiently use bandwidth.

“If you were collecting streaming video of a moving hostile target, you could dial up or dial down the data compression capability so that you are only able to view what you need,” said Loren Thompson of the Lexington Institute, a Virginia-based think tank. “The idea behind data compression is that you use only as much transmission capacity as needed to get the fidelity of messages you want to see. By tinkering with data compression, you can get much more carrying capacity out of available bandwidth than most people realize.”

But compression and even the new JTRS radios aren’t going to solve the Army’s bandwidth problems, Bolton said.

“Whether you ask me to compress, prioritize or go to a different band, those are all Band-Aids. Eventually, you run completely out of bandwidth. Now what? I need that information,” he said.

One possibility, albeit long-term, may lie in the exotic world of quantum mechanics, where researchers are pondering methods of communication that use no radio transmissions at all, he said.

“My gut feeling is if we were allowed to come back in 100, or certainly 500 years, nobody would use electromagnetics and resulting bandwidth to communicate because it is a bankrupt approach,” Bolton said. “All I know is, we can’t go on with electromagnetics.”

Several physicists said there are early theoretical models now examining the possibility of using quantum physics to communicate information faster than the speed of light.

In the meantime, the Army is taking a pragmatic approach to the problem. Units that are testing early versions of FCS technology at Fort Bliss, Texas, are pushing the new systems to their limits — but also practicing to see what they can still do when parts of the network go dead.

A soldier who gets used to fighting amid a wealth of information is hampered when that network goes down, according to a 2006 RAND study.

“Message latency (delays) affected warfighter effectiveness by as much as 50 percent for a selected scenario,” the study said.

Bolton said the Army is trying to figure how to fight with its new gear when it works as advertised as well as when it doesn’t.

“That is going to be the key to success in the future for us,” he said. “We want to red-team the network and see what happens if some of it goes away.”
Faster radios

The next-generation JTRS radios move data far faster than existing radios. For instance, JTRS radios running the Soldier Radio Waveform can transmit up to five megabits per second, far more than today’s Enhanced Position Locating Reporting System, or EPLARS, radios, which move 200 kilobits per second, or the Single Channel Ground-Air Radio System, or SINCGARS, radios which move about 8 kilobits per second.

These new radios will provide a huge advance in access to information for troops in headquarters, in vehicles and even on foot.

“You can move maps and imagery as well as transmit voice and data with a tactical Internet capability,” said Howard Pace, JTRS deputy program manager for the Pentagon.

But networked waveforms, such as SRW and Wideband Networking Waveform, use more of the electromagnetic frequency spectrum than today’s radios.

“WNW is capable because we are using a large chunk of spectrum to broadcast at megabits per second with continuous bandwidth,” Pace said.

Pace said the Pentagon must move more quickly to retire older radios so that the newer ones can have electronic room to operate.

“If you don’t decommission some of these waveforms, you are trying to take more from something that is not there,” he said. “As soon as SRW-capable radios show up, you need to take SINCGARS out. As WNW shows up, you need to take EPLARS out.”

But Pace’s boss, JTRS program manager Dennis Bauman, said that’s going to take some time.

“Part of the force will still be using SINCGARS until we introduce the new capability, so at least until we get WNW and SRW across the force, SINCGARS is here to stay,” Bauman said. “But once you get it across the force, you should be able to phase out waveforms like SINCGARS and EPLARS.”

Nor can the Army look beyond its narrow segment of the spectrum. Over the last few decades, the U.S. government has auctioned off to private companies many frequencies once reserved for the Pentagon, bringing in billions of dollars but constraining the options for military communications, Pace said.

Harvard University physicist Roy Glauber said the increasing use of frequency is a growing problem.

“The point is that every electromagnetic device uses a certain range of frequencies,” Glauber said. “So every electronic device has a bandwidth, so if you have another device with an overlapping frequency band, you will get overlap and cross talk. There is no alternative to having a bandwidth.”

End of Part 1



 

Edward Campbell

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Part 2 - Discussion

I am resurrecting a very old post and adding a civilian perspective from this article, which is reproduced under the Fair Dealing provisions of the Copyright Act from the Financial Post, to illustrate a natural resource problem ~ radio spectrum:

http://business.financialpost.com/2013/07/27/ruling-the-waves-behind-the-telecos-insatiable-hunger-for-wireless-spectrum/?utm_source=dlvr.it&utm_medium=twitter&__lsa=e4a4-c756
financial-post-logo.jpg

Ruling the waves: Behind the telecos’ insatiable hunger for wireless spectrum

Christine Dobby

13/07/27

Even George Cope, a wireless insider since the dawn of the cellphone, was blown away by the sector’s ravenous appetite for invisible radio waves when the government put new spectrum on the block five years ago.

“If you had told me the proceeds of the last auction in 2008 were going to be $4-billion – I was off by a couple billion,” says Mr. Cope, president and CEO of BCE Inc., the parent of Bell Canada.

Mr. Cope joined the industry at 23, built and sold a startup and helped launch Clearnet Communications Inc., the cellular provider Telus Corp. acquired in 2000 in a blockbuster $6.6-billion deal. He learned early in his career that it was a “big capital” business, but admits demand for mobile technology has outpaced his projections and continues to surge as the industry reinvents itself every 12 months or so.

“It all changed when the Internet went wireless – it really changed with smartphones. Now it’s all about video on wireless devices and ultimately it’s going to be a wallet and location services,” Mr. Cope says. “It is the Swiss Army Knife of technology.”

In an interview with the Financial Post this week, Mr. Cope made clear just how much he values protecting BCE’s access to the radio waves known as spectrum in an upcoming auction, echoing recent comments from his counterparts at rivals Rogers Communications Inc. and Telus.

The chief executives of Canada’s three national carriers are incensed with Ottawa’s policy on the wireless sector, which they say could lead to a U.S. giant running off with half of the most valuable spectrum to become available since the 1980s and leaving one of the trio empty-handed.

On the other side of the ring, the federal government says it is crafting policy to spur healthy competition and protect the interests of Canadians indignant over high monthly phone bills, onerous contract terms and no real choice between three players in an oligopoly.

Compared to European countries with well over one mobile device per person and even the United States, which has a cellphone penetration rate of more than 100%, the number of subscribers per capita in Canada is about 80%.

Many consumers hope that would change with the arrival of a company like Verizon Communications Inc., which they envision bringing ramped up competition and lower prices.

Right now Rogers, Telus and BCE together control 85% of the wireless spectrum the government has already handed out, while a handful of smaller players lay claim to the balance with none holding more than a 3% block.

“The biggest issue is just getting more spectrum,” says Alek Krstajic, the chief executive of Toronto-based startup carrier Public Mobile. “The government is essentially saying, ‘These highways, we’re not going to let the incumbents control them.’”

Gregory Taylor, principal investigator for Canadian Spectrum Policy Research, a research team at Toronto’s Ryerson University, says with 20-year licence terms at stake, decisions on spectrum policy being made now will shape Canada’s digital infrastructure for a long time to come.

“A key point has got to be that this is a public resource and we often forget about that,” he says.

Industry insiders, fond of analogies to describe the importance of securing lots of spectrum, often compare it to a system of roadways that can handle fast-moving and high-volume traffic when expanded to four wide lanes but jam up when restricted to meandering one-lane roads.

There is, therefore, a strong impulse among all players in the wireless industry to capture the largest block of spectrum they can get their hands on, according to Stuart Jack, partner at Ottawa-based strategy consulting firm Nordicity.

“In every market in the OECD that’s the trend we’re seeing. There is a concerted effort to make sure in the future that they will have enough spectrum to do what they want,” he says, adding that mobile data consumption habits help explain their voracity.

For example, Cisco Systems Inc. projects that by 2017, consumer mobile data traffic in Canada will grow tenfold from where it stood in 2012, increasing at a compound annual growth rate of 57%.

Canadians will have 255 million mobile devices by 2017, up from 140 million last year, according to Cisco, and monthly mobile traffic will be 122 Petabytes, akin to streaming 30 million DVDs per month.

These numbers represent a huge opportunity and lend context to why Canada’s largest mobile providers as well as regional operators and even the financially stressed startup carriers are prepared to spend billions between them at the next spectrum auction.

If wireless airwaves are all like beachfront property, mobile operators say, then low-band frequencies are the priceless — and prized — Malibu shoreline.

Mobile services operate on specific frequency bands between 300 and 3000 megahertz along the electromagnetic spectrum. Other bands of spectrum in the same range are designated for uses such as air traffic control, search and rescue and GPS (global positioning system).

Transmitters at cellular sites – whether installed on rooftops, hydro poles or specifically designed cell towers – reuse different spectrum frequencies to deliver service to mobile phones.

For their part, handsets contain chip sets specifically designed to communicate with frequencies in certain bands and while some can function across a number of bands, that tends to put a drag on battery life.

Since radio spectrum has many possible uses, if countries did not use the same frequency bands for complementary purposes, cellular services across borders could be a disaster. So an agency of the United Nations, the International Telecommunication Union, designates certain bands for cellular use and countries around the world allocate spectrum in those bands at roughly similar times.

The spectrum Canada first licensed for mobile cellular services in the 1980s was in the lower end of the range in the 800-megahertz band, known as the cellular band. Lower-frequency radio waves have longer wavelengths and can travel longer distances and penetrate buildings and other obstacles with ease.

That also means operators can build fewer cellular towers than they would have to with higher-frequency spectrum with less optimal propagation qualities.

In later decades, the government allocated spectrum in higher frequencies and while operators were happy to build networks with those airwaves, they are more enthusiastic about the next auction of spectrum in the 700-megahertz band, which used to be allocated to over-the-air television and became available after its transition to digital.

“We need 700 spectrum in order to be able to provide LTE cost effectively to our rural customers,” says John Meldrum, vice-president of regulatory affairs at Regina-based SaskTel. He says the provincial carrier (which has built an HSPA network, a form of third-generation digital transmission) wants to upgrade to long-term evolution or fourth-generation technology.

“We could do it without adding extra towers if we could get the 700 spectrum,” he says, adding that SaskTel sees that as crucial to ensuring rural customers have access to quality service.

“I don’t think I’m exaggerating when I say 700 is the best spectrum the government has ever made available for wireless services,” says Mirko Bibic, chief legal officer at BCE.

The last time a comparable spectrum band was available was when cellular technology was in its infancy in the 1980s. While the government now sells spectrum to the highest bidder (taking in $4.3-billion during the 2008 auction), in 1983 it awarded spectrum on the basis of a competitive review, a process often referred to as a “beauty contest.”

Cantel, a company formed by a group of telecom entrepreneurs including Ted Rogers, won a national licence and the government awarded the remaining half of available spectrum on a regional basis to local telephone operators.

The government handed out more licences in 1995, this time for a higher-frequency band known as PCS (personal communication system) spectrum between 1850 and 1990 megahertz.

To encourage new competition it granted airwaves to two new players – Clearnet and Microcell Telecommunications Inc. – as well as existing licence holders.

Through a wave of consolidation throughout the 1990s, Telus was formed out of the Alberta Government Telephones Commission, the city of Edmonton’s telephone company and a merger with BC Tel in 1998, capped off with the Clearnet acquisition in 2000.

Ted Rogers initially put his own money into Cantel; but by 1989 Rogers Communications invested about $1-billion from the sale of U.S. cable assets into the wireless business. In 2004, Rogers bought out the remaining interest in Cantel for $1.8-billion and acquired financially struggling Microcell for $1.6-billion.

When Ottawa was formulating the rules for the 2008 auction of AWS (advanced wireless services) spectrum in the 1700- and 2100-megahertz frequencies, it set aside 45% of the licences specifically for new entrants to the wireless market in an effort to promote new competition.

Those licences were sold at a discount and included a ban on their sale or transfer for five years, a moratorium period that is set to expire at various points next year depending on when the owners registered the licences.

Since then Quebecor Inc.-owned Videotron has built a wireless business in Quebec, regional players SaskTel and MTS Inc. have enhanced their cellular services and Nova Scotia-based cable operator Eastlink Inc. launched LTE services earlier this year.

Startup carriers Wind Mobile and Mobilicity both won set-aside spectrum licences in Ontario, Alberta and British Columbia, but beset by a series of challenges, both are now for sale.

Stewart Lyons, president and chief operating officer of Mobilicity, says interest in the company — including a bid by Telus shot down by Ottawa — has come primarily due to its spectrum holdings: “We always believed it would be relatively valuable real estate.”

The third of the trio of startups, Public Mobile, bought a block of rarely used spectrum in the 2008 auction and built a network in Ontario and Quebec. Last month it announced a recapitalization with new backing from Thomvest Ventures as some of its original investors got out. While Thomvest has committed to support the company until it is cash-flow positive, Mr. Krstajic says he is open to sale opportunities.

The regional players have had some success, but the dismal prospects of the new entrant carriers in Ontario, Alberta and B.C. have been a disappointment for the government, which has become more determined over the past six months in its call for at least four players in every region.

And while spectrum auctions always present an opportunity for investors even if they don’t plan to build, Ottawa’s policy on the wireless file and the way it has structured the auction rules have also drawn the interest of U.S. telecom giant Verizon.

The rules around investment in the telecommunications sector changed last year, and now foreigners can acquire Canadian companies with revenues of up to 10% of the overall telecom market, which was $42.7-billion in 2011, the latest figure available.

The government blocked Telus from acquiring debt-ridden Mobilicity’s spectrum in early June. Ottawa subsequently made clear it will not condone deals that allow the incumbents to purchase new entrants’ set-aside spectrum.

A company like Verizon, however, would be able to buy Mobilicity and its larger peer Wind Mobile and the New York-based company said last week it is indeed considering the opportunity.

Up for auction are four prime blocks of 700-megahertz spectrum but the incumbent players are restricted to bidding on no more than one, while new entrants can bid on up to two blocks.

Verizon, which owns the two “Upper C” blocks of 700 spectrum in the United States, would likely want to acquire the same airwaves in Canada.

Now the big three Canadian carriers are waging a public campaign in protest of what they say are “loopholes” in government policy that have opened a door Verizon could soon ram a truck through.

Calling for a “level playing field,” they are asking the government to change auction rules to open up competition before a Sept. 17 deadline for initial bids.

That argument is rich, critics say, coming from companies that control the vast majority of existing spectrum, much of which they received for free in the 1980s and 1990s.

Rogers and its telephone company peers counter that they took huge risks in building those initial networks and have paid expensive annual licence fees for years.

“The average Canadian tends to look at this from how it will affect their monthly bill – so a big company with deep pockets like Verizon can come in and not just participate in the auction but possibly dominate it and become instantly a large carrier across the country,” spectrum researcher Mr. Taylor says.

But he adds that there are real concerns about the U.S. carrier’s long-term commitment to Canada and whether it would build in rural areas.

Plus, while it has huge buying power due to its 100 million wireless subscribers and could provoke price competition in Canada, financial analysts note that Verizon is a premium carrier in the United States and not likely to bring a discount model north of the border.

“I think that to look upon the arrival of Verizon as some sort of saviour of the Canadian system is a bit naïve,” Mr. Taylor says. “On the other hand, most Canadians have no great love for the domestic incumbents either.”


The spectrum is a finite natural resource which is, as the article mentions, managed on a global basis. It is, in a way, rather like oil: when oil was $10/barrel there was no way to recover heavy oil in Alberta; at $50/barrel the oil sands are viable; at $100/barrel all manner of new technologies are available. It is similar with spectrum: as demand drives up the price good engineering will increase the supply by making each Hertz carry more and more information by using more and more sophisticated coding and modulation techniques.

It is a fact that, globally, the military remains the biggest single user of spectrum. In simple bandwidth terms most military spectrum is used for radar and most of that spectrum is not of much interest to civilians ... yet. But as (or if) consumer demand continues to grow then civilians - and revenue hungry governments - will start to cast covetous eyes on the military's spectrum. The military is, routinely - and with some, but not much justification - accused of hoarding spectrum. This, generally, reflects a poorly informed civilian sector (industry and government) but the explanations are often complex and, sometimes, cloaked in secrecy.

But the military is not defenceless: its voice within national governments remains strong and militaries - even ones who are not allies or even friends - cooperate internationally to defend bands against civil/commercial encroachment.

For the time being when we say military we mean, for tactical operations, mobile and mobile equals radio which requires spectrum. We can, as we have demonstrated over the past half century, make any spectrum band do more and more but always at a cost.

Do you want more new ships or better defences for the ones you have? Both have serious spectrum implications and spectrum costs money - DND pays Canada real money for the spectrum it uses and those dollars cannot, then, be used to buy food, fuel or ammunition. Most experts, including many in the military, argue that the military should pay for its spectrum to encourage optimum use.
 

a_majoor

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Since I have only a limited background in the area, I am dazzeled by the various advances I see (and sometimes I post them on the Recent Wafare Technologies page).

Techniques like polarization, advanced algorithms for packet routing, multiplexing, high speed frequency hopping etc. are all being developed and touted as means of speeding up networks, increasing throughput and making more efficient use of the spectrum. My question, then, is this not enough? And if so, what can we do to help the situation?
 

Edward Campbell

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Thucydides said:
Since I have only a limited background in the area, I am dazzeled by the various advances I see (and sometimes I post them on the Recent Wafare Technologies page).

Techniques like polarization, advanced algorithms for packet routing, multiplexing, high speed frequency hopping etc. are all being developed and touted as means of speeding up networks, increasing throughput and making more efficient use of the spectrum. My question, then, is this not enough? And if so, what can we do to help the situation?


think-before-you-speak.png


Is the message you are about to send really necessary? What about the report you are about to demand from subordinates? If it is necessary, do you really need it now? Etc, etc, etc ...

I have a nagging suspicion that we you (serving folks) talk too much. I watched the exponential growth in communications capacity in the 1960s, 70s, 80s and 90s without, ever, seeing a concomitant increase in operational effectiveness ... there were some increases, especially in the 1960s, but the law of diminishing returns seemed to set in sometime in the 1980s and more and more radios, each with more bandwidth, didn't seem, to me, anyway, to add all that much to our operations.

Radios (including radars) are good things, we ought to have lots of 'em ... for a whole lot of reasons - security, conservation of spectrum, and other - we should use them with caution.
 

Fishbone Jones

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Perhaps someone can explain to me why an Afghan\ Indian\ Pakistani that makes < $200 US a year can afford a cell phone, and get reliable service, but we have to pay approx. $35 and up\ month for the same service.
 

Jammer

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Because we as Westerners are not satisfied with just using a cell phone to just talk...we are slaves to smartphone technology and wanting it to do everything our PCs can. The vast majority of carriers there only provide basic service anyway. They are also subsidized by the national governments.
 

Edward Campbell

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recceguy said:
Perhaps someone can explain to me why an Afghan\ Indian\ Pakistani that makes < $200 US a year can afford a cell phone, and get reliable service, but we have to pay approx. $35 and up\ month for the same service.


Maybe because we are burdened with a Marxist legacy from the 1960s and '70s - specifically the Broadcasting Act (1968) which: confirms CBC's position as a national broadcaster; strengthens already stringent restrictions on foreign ownership; requires that Canadian programming be created mainly by Canadians; confirms the unproved (and downright silly, in my opinion) notion that the broadcasting system can strengthen Canada's cultural, social and economic structures; and creates the Canadian Radio-television Commission (CRTC), a new regulatory agency to replace the old Board of Broadcast Governors that becomes the Canadian Radio-television and Telecommunications Commission (CRTC) in 1976; and then the Canadian Radio-television and Telecommunications Commission Act which  expands the CRTC's jurisdiction to include telecommunications companies.
 

chrisf

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I'm going to go out on a limb and say most of our problem is from hanging on to out dated technologies, for backwards compatibility, so we can use old out-dated equipment.

Many of the "modern" advancements in communications aren't all that new, they just haven't been implemented.

Think about how much bandwidth could be freed up if all AM communications were changed to FM? Think about how long it's taken (and is taking) to change from analog to digital broadcast television?

A few years ago, I worked for the local power company, doing the pole engineering to start installing fibre optics... we had to install bigger poles in a lot of places to bare the extra weight of the fibre optics, the fibre optics were only tiny, maybe a centimeter diameter, but the existing poles were already over loaded from an enormous amount of copper communications plant installed on them... several feet of copper could easily be replaced by a centimeter of fibre... the copper won't be going anywhere for I'd say at least 50 years though, because it's still in use...
 

George Wallace

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a Sig Op said:
I'm going to go out on a limb and say most of our problem is from hanging on to out dated technologies, for backwards compatibility, so we can use old out-dated equipment.

Many of the "modern" advancements in communications aren't all that new, they just haven't been implemented.

Think about how much bandwidth could be freed up if all AM communications were changed to FM?

Ummm?  I am not a Sig Op, but even I know that a radio wave is a radio wave.  You can change technology all you like, but you are not going to change radio waves nor wavelengths of Light in this millennium.  Going Digital from Analog has not changed any wavelengths, just the means of transmitting and receiving them.  Any problems you had dealing with Frequency wavelengths in the past, you will still face in the future. 
 

Edward Campbell

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Going digital, in pretty much every radio service, conserves bandwidth because you can pass more information in the same bandwidth or pass the same information is narrower channels.

With specific regard to AM (medium frequency (300 kHz to 3MHz)) broadcasting: it, that frequency range, still has HUGE advantages in range/coverage which makes it very valuable for service in rural areas and for wide area "low fidelity" coverage in dense urban areas.
 

Jammer

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Those freqs have very limited range and will require repeaters all over creation...ever notice the proliferation of cell towers...
 

chrisf

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George Wallace said:
Ummm?  I am not a Sig Op, but even I know that a radio wave is a radio wave.  You can change technology all you like, but you are not going to change radio waves nor wavelengths of Light in this millennium.  Going Digital from Analog has not changed any wavelengths, just the means of transmitting and receiving them.  Any problems you had dealing with Frequency wavelengths in the past, you will still face in the future.

What do wave lengths have to do with anything? I think the point flew right over your head there..

"new" technologies change how we use the resources we have... stuff like side bands, modulation type, and channel spacing all became "standard" a long time ago... we could easily use more narrow side bands, and reduce channel spacing, but we (The whole world) don't, because we're so heavily  invested in the standards we have.

Think about the digital TV example... digital transmission is not new, but it's only in the last couple of years that it's being adopted, because of band congestion... it hung around so long because when the switch is made to digital TV, older television sets can't receive the signal...

We could free up an enormous amount of bandwidth if every communications device suddenly went to digital... we could completely re-arrange entire portions of the spectrum... but it'll never happen, not in the near future anyway... because suddenly your car radio won't be compatible, suddenly McDonalds will need to get new wireless headsets for their drive through, suddenly countless FRS walkie-talkies sold over the counter won't be compatible...

"AM" is not a frequency range, "AM" is a modulation type... it just happens that there's a frequency band that we use primarily AM to transmit in... AM needs a wider channel spacing, and only has two side bands vs an theoretically unlimited number of side bands in FM... *but* because when first invented, we standardized AM on those frequencies, we're now stuck with AM, because of that standard.
 

Jammer

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AM does not provide the cleanest broadcast...sure it has range, but it degrades over distance.
 

George Wallace

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a Sig Op said:
What do wave lengths have to do with anything? I think the point flew right over your head there..

I think the point is flying right over your head.

Heavy cloud, obstructions of any sort, still block my signals; analog or digital.  You can not change radio waves.  What they carry is different, but what blocks that wave, still blocks what it carries.
 

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Jammer said:
AM does not provide the cleanest broadcast...sure it has range, but it degrades over distance.


Indeed, but digital radio at that band - which is widely used in the US (iBiquity's in-band on-channel (IBOC)), even for classical music - is clearer (less susceptible to naturally occurring noise), but it doesn't degrade "gracefully" because digital receivers have more defined thresholds.
 

Robert0288

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a Sig Op said:
What do wave lengths have to do with anything? I think the point flew right over your head there..

"new" technologies change how we use the resources we have... stuff like side bands, modulation type, and channel spacing all became "standard" a long time ago... we could easily use more narrow side bands, and reduce channel spacing, but we (The whole world) don't, because we're so heavily  invested in the standards we have.

Think about the digital TV example... digital transmission is not new, but it's only in the last couple of years that it's being adopted, because of band congestion... it hung around so long because when the switch is made to digital TV, older television sets can't receive the signal...

Speaking of spacing, I wonder if we convert current FM radio stations into using cell phone technology to shrink their overall RF band footprint...  Though it would never actually be done.
Tdma-frame-structure.png
 

chrisf

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George Wallace said:
I think the point is flying right over your head.

Heavy cloud, obstructions of any sort, still block my signals; analog or digital.  You can not change radio waves.  What they carry is different, but what blocks that wave, still blocks what it carries.

No, the point is definitely flying over yours :) you missed the poit I was making in the beginning.

Not saying use different frequencies, saying use those frequencies differently.

"Am" is not a band, it's a modulation type. The frequencies that we currently use "am" in are typically in the lf/mf/Hf bands.

The waves still propagate the same whether yourself am or fm, but we use am in those bands because its the established standard.

Am you get two side bands, upper ad lower, that's it. If we (the world) was to stop using am in those bands and use fm instead, which has a theoretical infinite number of side bands (there is of course a practical limit, but even with current standard the channel spacing for the bands we use for fm is much narrower.

 
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