[sarex] Re: FYI

["David C. Johnson" <bh855@xxxxxxxx>]

Gump, Larry wrote:
> 
> The Death of HF Radio Operation?
> 
>                                              Opinion Column
> 
>                                     Ed Mitchell, KF7VY, vbook@vbook.com
> 
>            Amateur Radio has long dealt with challenges to HF operation
> including restrictions on antennas and poorly
>            built consumer electronics that are highly susceptible to nearby
> radio signals.
> 
>            A new, and very challenging threat has emerged in the form of
> home computer networks - in particular both
>            home computer and home entertainment distribution systems that
> use unshielded, "twisted pair" copper wiring
>            or AC line wiring inside homes to transmit high speed data
> signals. Incredibly, these systems rely on signals
>            in the 2 Mhz to 30 MHz range[1] running over unshielded wiring.
> These systems generate broadband
>            radio frequency interference and are highly susceptible to
> interference from legitimate HF radio
>            transmissions. In just 2 to 3 years, the odds are that every
> other house in your neighborhood may be using
>            one of these HF-based network technologies.
> 
>            Hams have long dealth with interference to and from consumer
> devices - but in the past, the problem was
>            typically due to fundamental signal overload problems and the
> inability of consumer electronics to tolerate
>            nearby radio signals of any type. A variety of techniques have
> been developed to address traditional
>            interference problems ranging from the use of high pass filters,
> RFI chokes and ferrite beads, shielded cabling
>            and a variety of other simple solutions.
> 
>            The computer network inteference problem cannot be solved through
> the installation of a simple filters. In
>            fact, it may not be solvable at all since these devices are
> operating directly within the HF radio spectrum and
>            are using unshielded wiring for their links.
> 
> 
>            The Demand for HomeNetworks
> 
>            There is genuine demand for home computer network solutions.
> According to an article in Cnet News [2], an
>            estimated 54% of U.S. homes will have multiple computers as of
> the year 2001. Because most homes are
>            not configured for network cabling, the networking industry has
> adopted a mantra of "No New Wires" to
>            emphasize solutions that use existing household AC wiring,
> telephone wiring, or Part 15 unlicensed wireless
>            data systems.
> 
> 
>            Telephone Wiring-based Home Networks
> 
>            A leading home network technology uses existing home telephone
> wiring to do double duty with both voice
>            and data signals. Voice signals occupy the spectrum lower than 4
> khz. ISDN and xDSL services occupy
>            spectrum (typically) between 25 khz and 1.1 Mhz. In order for
> home phone networking to co-exist with
>            existing functions, home phone networking occupies frequencies
> above 2 Mhz. One product that is available
>            now is called HomeRun, from Tut Systems. This product provides a
> 1 Mbps data rate by modulating a data
>            signal between 5.5 MHz and 9.5 MHz with a carrier frequency at
> about 7.5 Mhz. This spans the popular 7
>            Mhz Amateur Radio allocation. Tests that I conducted last year
> demonstrated that low power 7 MHz RF
>            signals causes massive packet loss in the data network. Tests
> showed some susceptibility to other sources of
>            RF over a broad frequency range; however, the only severe source
> was transmission on 7 Mhz. This
>            technology also generates weak, broadband noise across the
> spectrum, consistent with a device operating as
>            a Part 15 unintentional emitter.
> 
>            HomeRun is a first generation product. The technology is evolving
> rapidly to deliver much higher data rates -
>            10 Mbps later  in 1999, and still faster later on. In
> mid-February, a 10 Mbps standard was formerly
>            proposed to the Home Phone Networking Alliance. To provide higher
> speeds, the technology will
>            expand its spectrum usage to the entire bandwidth of 2 to 30 Mhz.
> Because this technology is
>            operating over unshielded copper wiring, and based on my tests
> conducted in 1998, it appears likely
>            that Amateur transmissions will greatly interfere with home phone
> networking, possibly over a very
>            wide area due to susceptibility to signals on the same
> frequencies.
> 
>            Worse, home phone networking will not be confined to computer
> data applications, which due to their
>            packet and error correcting protocols, can accommodate
> intermittent interference. The long term direction of
>            home phone networking is the routing of home digital video
> signals, digital audio and other entertainment
>            signals. Data loss in these streaming data applications will be
> extremely apparent to the user of the network.
>            Examples include routing a digital TV, digital satellite, or DVD
> signal to one or more displays located in a
>            home. Data rates will be pushed ever higher in order to
> accommodate future High Definition TV signals
>            (which require about 19 Mbps data rates).
> 
>            Several companies are working together on home phone networking
> technology. Tut Systems received
>            financing from many sources including AT&T and Microsoft. Compaq,
> Intel, and Diamond Multimedia have
>            licensed the technology. Another company, Epigram, expects to
> ship 10 Mbps technology chipsets in the first
>            quarter of 1999.
> 
> 
>            AC Power Line Networking
> 
>            Another technology sends signals over AC power wiring inside the
> residence. One company, Phonex, sells a
>            telephone extension system that can be used to locate a wired
> phone, modem, or cable TV/satellite TV "set
>            top box" phone connection - to any location inside the home.
> Current products modulate the signal on 3.520
>            Mhz using a FM subcarrier. TCI cable company distributed many of
> these products to users of their
>            set-top-boxes and digital cable converters. The DISH Network
> satellite network also sells these units at their
>            web site. The ARRL recently brokered a deal with TCI such that
> TCI has agreed to replace the 3.52 MHz
>            units with new units that operate at a different radio frequency,
> to eliminate interference potential between
>            Amateur operations in the 3.5 to 4.0 Mhz band. Still, several
> million of these units are in operation today and
>            are not covered by the TCI replacement program.
> 
>            I recently tested a Phonex 3.520 Mhz unit and was surprised at
> the level of RF noise it leaks, especially
>            considering that this is a "wired product" not a wireless
> product. Worse, its basically broadcasting the users
>            wired telephone conversations on HF! The signal not only emits
> from the wiring of the house where it is used,
>            but it also leaks back into the AC utility grid. Using a handheld
> shortwave receiver, I picked up S9 signals
>            when near the power line, a block away from the home unit. I did
> not pursue the signal any further than that
>            but it seemed likely that the power line would still be radiating
> the signal at two blocks from the home.
> 
>            Not only does the Phonex product leak outwards, but also it is
> susceptible to Amateur transmissions in the
>            3.5 Mhz band.
> 
>            Phonex is an example of a class of products that use electrical
> power lines for signals. Other products are
>            coming to market that deliver data over household wiring in a
> similar fashion. One product from Intellon,
>            operates at 1 Mbps and they (and other manufacturers) claim they
> will eventually achieve 10 Mbps
>            performance. Present systems modulate their signals well below
> any Amateur HF bands; however, it is
>            unknown where their 10+ Mbps products will operate. It is likely
> that these will generate signals well into the
>            HF spectrum. At this point, it is unknown if power line
> technology will become a success. The power line
>            networking industry is fragmented and has not yet formed an
> industry trade group, as was done by the home
>            phone networking companies. Never the less, Intellon has licensed
> its power line technology to Microsoft
>            Corporation for use in future products.
> 
> 
>            HF Spectrum Filling with Digital Noise Makers
> 
>            As described in Part 1 and Part 2 of "The Great Broadband
> Internet Hoax" series, two-way cable modems
>            are using the 5 to 40 Mhz bandwidth for upstream cable modem
> signaling. How bad will this leakage be? I
>            just finished a several mile walk around my neighborhood and
> found television carrier leakage from the cable
>            system; fortunately, none of it was within the Amateur radio
> bands. With two-way cable uplinks in the HF
>            band we are likely to have leakage on top of existing Amateur HF
> allocations.
> 
>            A problem that may further compound this situation is that home
> phone networking and cable modems are
>            being routed through existing, internal home wiring systems, the
> quality of which is often quite poor (in other
>            words, the "twisted pair" may not even be twisted). When my
> mother-in-law had a cable modem service
>            installed, the cable company had to replace all of the internal
> wiring to get the system to work properly.
> 
>            The 2 to 30 Mhz spectrum is rapidly filling with digital
> noisemakers. Not only do these systems emit RF noise
>            but they are very susceptible to interference from clean and
> legal Amateur radio transmissions. There is no
>            simple filtering arrangement to eliminate the interference to
> Amateur radio or from Amateur radio to home
>            networks.
> 
>            Home network products promise significant challenges to future
> Amateur HF operation in residential areas.
>            With estimates that 54% of homes will have multiple PCs by 2001,
> and that networking such systems is a
>            high priority, it is a guarantee that Amateur radio operators
> will be in close proximity to these noisemakers
>            and HF operation will become a significant source of interference
> to home networks. Specifically, for the
>            75% of the U.S. population that lives in urban areas, nearly all
> in-home phone network users will be in range
>            of Amateur HF transmitters capable of causing interference. Major
> companies are backing these phone and
>            AC line technologies: AT&T, Intel, Microsoft, Compaq, TCI and
> many others. Therefore, it is likely that
>            these products will become widely available and used by millions
> of home computer owners.
> 
> 
>            Where Does This Leave Amateur Radio?
> 
>            Legally, Amateur radio operators have Federal communications law
> on their side. Home networking
>            equipment operates under Part 15 rules and must put up with any
> interference it receives from licensed radio
>            services. Realistically, while the law is on the side of Amateur
> radio, home network and Internet users vastly
>            outnumber Amateur radio operators. The politics of the situation
> do not favor Amateur radio operation on
>            the HF bands, as we know it today.
> 
>            Oddly, the ARRL continues to promote an incentive licensing
> scheme that puts all of the incentives in the HF
>            bands (4 out of 5 the existing license classes s are HF-centric).
> The ARRL is currently conducting technical
>            tests near 5 MHz for the purpose of potentially requesting
> additional HF radio spectrum for Amateur Radio,
>            and in the recent license restructuring proposals, the ARRL
> strongly supported retention of telegraphy
>            proficiency (historically used most extensively at HF)
> requirement in the Amateur service. While these are
>            admirable goals, the reality of the world we live in today is
> that HF operation is rapidly becoming impossible
>            for most Americans in a world filled with antenna prohibitions on
> all new housing and where homes will
>            soon be filled with home networks operating in the 2-30 MHz HF
> spectrum. Literally, Amateur Radio is
>            potentially off limits to most Americans. Is it any wonder our
> numbers are decreasing?
> 
>            Our Amateur Radio "product" is significantly out of step with the
> real world, which may explain why the
>            ARRL recently reported the loss of 14,000 members, and the
> overall U.S. Amateur population declined in
>            1998 by 1,090 individuals. Worse, with nearly 1 in 3 Amateurs
> over the age of 65[3], and very few
>            Amateurs under the age of 40, these numbers may indicate that the
> Amateur Radio service is literally dying.
>            A few years back, slow Amateur radio service growth was based on
> poor HF radio propagation due to the
>            bottom of solar sunspot cycle. With the sunspots now doing their
> thing, that theory is largely moot.
> 
>            In my humble opinion, a hobby radio service that is declining in
> numbers may be in an extremely difficult
>            position to defend its HF operations in the presence of vastly
> more home computer and digital entertainment
>            consumers. There is a fair amount of evidence that our Amateur
> radio "product" needs a wholesale rethinking
>            and a major new vision for the 21st century. I have suggested
> ideas for new directions in past Opinion
>            columns, and I won't repeat them here. The bottom line is that
> the ARRL[4] needs to exert a strong vision of
>            a "new" Amateur Radio service for the 21st century, consistent
> with the new world that we live in. What can
>            you do? You need to communicate your thoughts on these issues
> directly to your ARRL Director.
> 
>            [1] "The Home Phoneline Networking Alliance", white paper,
> http://www.homepna.org
> 
>            [2] "Tut Systems soars after IPO",
> http://www.news.com/News/Item/0,4,31584,00.html
> 
>            [3] February 1997 QST reviewed a survey of ARRL members. This
> data point is from that survey and may
>            not be indicative of the overall Amateur population.
> 
>            [4] In both written (see http://www.nocode.org) and verbal
> comments made to amateurs, the FCC has
>            stated clearly that it primarily accepts input on Amateur radio
> matters from the ARRL or the QCWA and
>            generally does not act on specific proposal from other entities.
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