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PA2AGA > HDDIG 23.09.99 05:34l 204 Lines 7396 Bytes #-9769 (0) @ EU
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Subject: HamDigitalDigest 99/238C
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>.
------------------------------
Date: 21 Sep 1999 18:22:29 GMT
From: "kk" <kkmdg@hotmail.com>
Subject: help for a problem
I have a problem for my test at university, telecommunications course.
The system is a 2-psk with a carrier ar omega0.
The propagation block is modeled by a two-ray signal: one direct ant other
reflected, with an relative amplitude ro, and relative delay tau.
At receiver, the filter is matched at modulation impulse.
the questions are:
1) calculate the power of carrier after the propagation block (assume Vo
the amplitude of carrier)
2) dimostrate that the probability of error is:
P= 1/4 erfc(sqr(W)) + 1/4 erfc((sqr(W)(1-(1/1+ro)2tau/T))
where W=Pr/2NoB
B=1/T (T simbol time)
Pr=Power of carrier before matched filter at after propagation block.
No= bilateral spectrum of noise.
Thanks for all reply.
Ing. G.D. (Napoli)
one101@oneonline.it
>.
------------------------------
Date: Tue, 21 Sep 1999 22:11:10 GMT
From: RA <ricear@hotmail.com>
Subject: help for a problem
On 21 Sep 1999 18:22:29 GMT, "kk" <kkmdg@hotmail.com> wrote:
>I have a problem for my test at university, telecommunications course.
>The system is a 2-psk with a carrier ar omega0.
>The propagation block is modeled by a two-ray signal: one direct ant other
>reflected, with an relative amplitude ro, and relative delay tau.
>At receiver, the filter is matched at modulation impulse.
>
>the questions are:
>
>1) calculate the power of carrier after the propagation block (assume Vo
>the amplitude of carrier)
>2) dimostrate that the probability of error is:
>
> P= 1/4 erfc(sqr(W)) + 1/4 erfc((sqr(W)(1-(1/1+ro)2tau/T))
>
>where W=Pr/2NoB
>
>B=1/T (T simbol time)
>Pr=Power of carrier before matched filter at after propagation block.
>No= bilateral spectrum of noise.
>
>Thanks for all reply.
>Ing. G.D. (Napoli)
>one101@oneonline.it
>
WTH has this got to do with Backrubs?
>.
------------------------------
Date: Tue, 21 Sep 1999 20:38:06 -0500
From: "George T. Baker" <w5yr@swbell.net>
Subject: help for a problem
I'm impressed, but what do you want? Isn't it *your* test?
72/73, George AMA 98452 R/C since 1964
Amateur Radio W5YR, in the 54th year and it just keeps getting better!
AutoPOWER Systems, Fairview, TX (30 mi NE Dallas) Collin County
QRP-L QRP-ARCI FISTS NORCAL ZOMBIE ARS 10-X 33.2 N 96.6 W EM13RE
kk wrote:
>
> I have a problem for my test at university, telecommunications course.
> The system is a 2-psk with a carrier ar omega0.
> The propagation block is modeled by a two-ray signal: one direct ant other
> reflected, with an relative amplitude ro, and relative delay tau.
> At receiver, the filter is matched at modulation impulse.
>
> the questions are:
>
> 1) calculate the power of carrier after the propagation block (assume Vo
> the amplitude of carrier)
> 2) dimostrate that the probability of error is:
>
> P= 1/4 erfc(sqr(W)) + 1/4 erfc((sqr(W)(1-(1/1+ro)2tau/T))
>
> where W=Pr/2NoB
>
> B=1/T (T simbol time)
> Pr=Power of carrier before matched filter at after propagation block.
> No= bilateral spectrum of noise.
>
> Thanks for all reply.
> Ing. G.D. (Napoli)
> one101@oneonline.it
>.
------------------------------
Date: Tue, 21 Sep 1999 10:51:09 -0500
From: "Charles Brabham" <n5pvl@texoma.net>
Subject: Let's Get Serious!
A large-scale packet network is and should be treated as a social entity. In
most if not all cases, it is the result of an organized effort by a club or
organization in the first place, so this should take no great leap of the
imagination. The trick is to match up that organization's structure and
attitudes with it's goals. This needs to be adjusted in all cases I've seen
here in the US, as these organizations are usually patterned after the
familiar repeater organizations hams have had going for quite some time, and
that model is not really up to the task.
Ask any packet networker who's been at it a while, and he will tell you
tales of burnout that would re-curl your short hairs. A few key people do
all the work, and everybody else is just along for the ride.
That's great, if you are only planning on putting up a few repeaters, but I
believe it is universally recognized that it doesn't work for very long with
a large-scale digital network. Once the initial growth spurt peters out,
things start going to the dogs.
Clearly, a different way of doing things needs to be looked into.
It's my feeling that there is a need to work on a model for setting up and
staffing an organization dedicated to building, developing and maintaining a
large-scale digital ham radio network. What specialized jobs besides "HF
coordinator" might be needed in order for the network to function as
efficiently, effectively and smoothly as possible?
One function that is regularly overlooked is a Funding Czar. Most ham
organizations get along just fine by collecting reasonable dues or maybe
having an occasional event such as a Ham-Fest in order to put a little
something in the kitty. A club that intends to run and maintain a
large-scale ham digital net needs to take funding a little more seriously
than that. Setting up a small cluster of local repeaters and running an
digital RF
network with a 600 mile footprint are two entirely different things. We need
to recognize that fact and act accordingly.
A funding Czar's main job would be to oversee the operation of a non-profit
organization. As with all non-profit organizations, it's main purpose would
be to generate funding and materials in order to perform a public service.
(emergency communications and scientific research, in this case) For this
reason, a professional should be hired and told that he will be generating
his own salary. Work out a legal and satisfactory cut, familiarize him with
your goals, and turn him loose.
There are numerous ways for non-profits to generate funds, including
accepting donations of radio equipment and even towers from local
corporations and government agencies that are upgrading to new equipment.
You get a stack of UHF Micors and rolls of used but good heliax, they get a
tax write-off for the market value of the equipment without having to market
it. Sell it all to your in-house networkers at a bargain price, or to other
hams at the regular market price.
Why not pay a few folks to clean up, recrystal and calibrate that stack of
rigs, each matched up with a modem or TNC for true "plug 'n play" medium to
high speed networking that can be done without a service monitor? Doing this
solves the "expert burnout" problem quite handily, and puts you in a good
position to have ready spares on hand for rapid repair of a node that
develops trouble. Just jerk out the whole setup and replace it with a new,
perfectly calibrated one and put the malfunctioning modem/radio pair in the
junk pile for parts or possible repair. An appliance operator job. No
burnout.
Since you can now afford to; Build parallel, redundant links so that the
To be continued in digest: hd_99_238D
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