On Fri, Jun 28, 2013 at 10:19 PM, Bill Vodall <wa7nwp(a)gmail.com> wrote:
(Please trim inclusions from previous messages)
_______________________________________________
Based upon
what the bell system guys were doing 50 years ago, it seems that 45Mbps
over
a 70-100km radio link appears it ought to be
doable.... but really,
10Mbps
over 50km would be a good start.
We don't all have mountaintop microwave sites....
Not everyone needs a microwave mountaintop site or even a decently tall
tower. bear in mind the items that would likely be hosted in sites such as
these would be more of a community resource such as many voice repeaters
are (and could be collocated with a club that had decent resources) The
resources and hardware at such sites would be for the most part pieces of
the network core, not the outlying networks that connected to it and used
it's backbone..
We have homes and ham stations in compromise locations
with city lots,
restricted antennas and big RF absorbing trees... 25W of 440 MHz
will probably get through where less power at higher frequencies
won't.
some will be somewhat limited, this is true but when it comes to effective
radiated power and RX gain I can easily outdo your 25W of 70cm at the
antenna feedpoint with a watt at 5760 or 10250 measured at the feedpoint of
an antenna of similar physical size. just because some may not live on top
of a 10,000 ft mountain peak with multiple 1000ft self supporting tower
structures does not mean they can't make good use of amateur microwave
frequencies. such antennas get smaller and easier to put up higher as the
frequency goes up. all that's needed is that you can link to the next node
from you or into the backbone network. some may be so limited as to only
be able to do so by internet tunneling. but that doesn't mean that those
who are not so limited should not build the network. Amateur microwave at
2.4GHZ and above is the proper place to do so. It gives the performance we
need with hardware most will find affordable and easy to use and
implement. If you're living on a city lot, my guess is that your next hop
neighbor ought to be much closer than if you're living 40miles out of
town. also in more densely populated areas you will need greater network
capacity and bandwidth to properly serve each user an equal experience. 20
people contending for use of a 56k link is much different than 1 user
having it to themselves.
The UDR56K is a good compromise real world solution
that is
probably the last best hope for AMPR data... The speed is good
enough for IM, email like this list, megabyte files (I know first hand
that's possible...) and facebook clones. That's way more than what
we have now...
on a per user basis, yes 56k may serve as a minimum bar but try sharing
that simultaneously with 20 other users. get 20 monkeys together in an
attempt to recreate the works of shakespere and you'll have that line
saturated for an infinite amount of time (ref rfc2795) as even they can
likely be trained to type faster than that. I know I can certainly read
what one of them could type at that speed. That said why shoot for a
minimum even if it is 5-6x faster than what we have stagnated upon for 20+
yrs. People didin't jump at 56k then, why should they now?
The price per node (about $600) is high and will be
hard for many to justify but it beats the competitors - ID1 is $1+K
for 120K raw data with 10W at 1.2 G or D710 with 50W of 9k6 data UHF
or VHF for $700.
yes, Dstar has effectively priced itself out of the market as to costly, to
little, to late while being an orphan that no one except amateur radio
uses. compare that however to the cost of a 1M dish and a professional
grade 802.11a 30dbm radio that goes from ethernet to RF. the 1M dish can
be had for 89usd and the radio for about the same.... so for under 200usd
you have a setup that can link that even in a somewhat rural setting ought
get you to your nearest ham neighbor. Compare this, faster and cheaper to
the UDR56k. I think people would go for the faster, easy to set up 200USD
solution.
Let's raise the bar a bit and get to building
a RADIO BASED NETWORK!
A harder problem than the RF is the WHY.... I can download Zombie
videos at 40MB (or ? - I haven't checked lately) from anywhere in the
world - why should I futz around with silly HAM regulations and
bureaucracy to do limited Ampr data... (FWIW I know the answers to
that...)
Why is actually easier to answer than it might seem. We'll start with
47CFR97.1 with which you and everyone on this list and with access to
AMPRNET ought be familiar:
§ 97.1 Basis and purpose.
The rules and regulations in this part are designed to provide an amateur
radio service having a fundamental purpose as expressed in the following
principles:
(a) Recognition and enhancement of the value of the amateur service to the
public as a voluntary noncommercial communication service, particularly
with respect to providing emergency communications.
Building such infrastructure enhances our ability to serve the public
especially in providing emergency communications in time of need. one of
the key uses for such infrastructure is tha ability to show up somewhere
and light up communication facilities between disaster sites that are
capable of moving voice and computerized data rapidly and efficently which
is also usable by those with little or no tech training. i.e. they attach
their laptop to the network at the disaster site and are online with all
other disaster sites they need contact with and have simultanious voice and
data connectivity between sites. By building such a network we augment our
ability to justify our existance.
(b) Continuation and extension of the amateur's proven ability to
contribute to the advancement of the radio art.
by building such a network we work to advance the radio art thus satisfying
another point of why we are allowed to exist.
(c) Encouragement and improvement of the amateur service through rules
which provide for advancing skills in both the communication and technical
phases of the art.
by building and operating such a network we advance our skills in
communication and technical phases of the art such as RF linking and TCP/IP
network operation and optimization. We serve as a training ground and
build our own skills along with the skills of others in the area of data
communications.
(d) Expansion of the existing reservoir within the amateur radio service of
trained operators, technicians, and electronics experts.
by building such network we expand the existing reservoir within the
amateur radio service of trained operators, technicians, and electronics
experts not only training those in technical arts they can take elsewhere
but also bringing greater numbers into the hobby for which this is their
primary interest in communications (not everyone is into 30second weak
signal contacts or chasing DX on 20M).
(e) Continuation and extension of the amateur's unique ability to enhance
international goodwill.
By building such a network on an international basis we create yet another
means to extend the amateur's unique ability to enhance international
goodwill.
those right there ought to be reason enough to get building... but I'll add
a few more:
Preservation of the precious frequency allocations we have available for
our use - anyone remember when we once had 220-222Mhz available to our use
and how due to perceived non-use it was reassigned for land mobile use
resulting in a 40% loss of the spectrum in the 1.25M band? We have
microwave bands that go largely unused and other services that would love
to run us out of them. By building such a network we put these bands to
effective good use
again, It serves as an avenue to bring more people into the amateur radio
fraternity.
it allows us a platform upon which creative applications can be built.
imaging having a minimum of 24 voice channels between each and every
mountaintop or backbone node as well as reasonably high data bandwidth.
that kind of trunking could be used for repeater linking or even allowing
multiple conversations over a wide area to be carried on simultaniously.
once voice is bits, it's just data like anything else on the network.
voice is only a start, the rest of the applications that may be built are
limited only by the imagination of the amateur radio AMPRNET community and
their willingness to advance the technical arts.
Eric
AF6EP
Eric
AF6EP
73
Bill, WA7NWP
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