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ZL3AI > APRDIG 25.10.06 09:11l 254 Lines 10365 Bytes #999 (0) @ WW
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Subj: [APRSSIG] Vol 28 #5, 1/2
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From: ZL3AI@ZL2BAU.#87.NZL.OC
To : APRDIG@WW
Today's Topics:
1. first.aprs.net (Gerry Creager)
2. RE: first.aprs.net (John Gleichweit)
3. Re: first.aprs.net (Joel Maslak)
4. RE: first.aprs.net (scott_at_opentrac.org)
5. Re: first.aprs.net (Joel Maslak)
6. RE: first.aprs.net (scott_at_opentrac.org)
7. Re: low power 2 meter exciter needed (Tyson S.)
8. Re: low power 2 meter exciter needed (Jason Winningham)
9. APRS over TCP/IP Question (Michael Stone)
10. Re: APRS over TCP/IP Question (John Habbinga)
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Message: 1
Date: Wed, 04 Oct 2006 12:22:53 -0500
From: Gerry Creager <gerry.creager_at_tamu.edu>
Subject: [aprssig] first.aprs.net
We got systems restored by about 0830z today.
Real story: Blew up an autotransformer at a switching yard
downconverting a 345kVa feed. Successfully lost 3 345kVa circuits.
Adverse effects in 4 counties and most of the University and surrounding
community was down for at least 3 hours. Slow restoration as the
utility folks brought smaller switching yards back on cautiously.
Campus had power by 0500z in some areas, and we started seeing some
systems back up ob 0700z after integrity checks on machines and disk arrays.
gerry n5jxs
--
Gerry Creager -- gerry.creager_at_tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX 979.862.3983
MAIL: AATLT, 3139 TAMU
Physical: 1700 Research Parkway, Suite 160,
College Station, TX 77843-3139
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Message: 2
Date: Wed, 4 Oct 2006 17:09:12 -0700
From: "John Gleichweit" <smokeybehr_at_sbcglobal.net>
Subject: RE: [aprssig] first.aprs.net
Ouch. You don't have UPS and Generator backup? The server farm for the
County here has a 750KVA genset and a RFB (really freakin' big) UPS setup
for the IT Services server farm. Fresno State has multiple server farms and
each has a UPS and genset of the appropriate size. Heck, the Bulldog ARC
server farm/radio room/repeater shack has a feed off the UPS and genset.
--
John "Smokey Behr" Gleichweit FF1/EMT, CCNA, MCSE
IPN-CAL023 N6FOG UP Fresno Sub MP183.5 ECV1852
List Owner x6, Moderator x4 CA-OES 51-507
http://smokeybehr.blogspot.com
http://www.myspace.com/smokeybehr
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Message: 3
Date: Wed, 4 Oct 2006 18:43:02 -0600
From: Joel Maslak <jmaslak-aprs_at_antelope.net>
Subject: Re: [aprssig] first.aprs.net
On Oct 4, 2006, at 6:09 PM, John Gleichweit wrote:
>Ouch. You don't have UPS and Generator backup? The server farm for the
>County here has a 750KVA genset and a RFB (really freakin' big) UPS setup
>for the IT Services server farm. Fresno State has multiple server farms and
>each has a UPS and genset of the appropriate size. Heck, the Bulldog ARC
>server farm/radio room/repeater shack has a feed off the UPS and genset.
There's always a single point of failure for a computer system, at least
that's what I've learned over the years. Sometimes it might be the
building's roof or something like that, but no matter what precautions you
take, sometimes things go wrong - such as generators not starting (despite
starting perfectly fine for the last 200 tests), UPSes failing to switch
over, transfer switches failing, limited supplies of diesel (or oil),
cooling systems not on backup, lack of a water supply in a power outage,
etc. So it's very possible to have backup power and still be severely
affected by a power outage.
And you've never experienced life until you've had a smoke detector detect
a cooling system leak (note that the room looks like it's filled with smoke
when certain cooling systems leak and you look in through a little window),
which discharges the fire suppression system and properly kills power to
the whole room. Or someone accidentally snags the big red button on the
way out the door (despite it being properly guarded). Or had the fire
marshall tell you that the diesel truck can't park there when the generator
is running. Or had a generator oil pressure sensor fail 5 minutes after
the generator starts. Etc...
Point is there are a lot of things that can go wrong in a modern server
room - even a properly designed one. (the examples I gave were all
examples that really happened to some of the facilities I've worked with -
these are properly designed data centers with a lot of money spent to keep
them reliable). Many of the failures happened during a real power outage,
despite weekly testing of the power systems (need I say that's also a
source of failure - what if it doesn't work during the test?).
So I'm kind of careful about bragging about backup capability - too often
the minute you brag about your own, you find out how little you have.
It's one of the benefits of APRS, though - it's pretty easy to get a
station - or even a digi - running without commercial power. I wouldn't
count on the phones and internet having the same reliability (recently a
double cable cut on a major telephone loop in Wyoming cut the northern half
of the state off from nearly all telecommunications - cell phones didn't
work, land lines worked only locally, 911 was down for dozens of
communities, people couldn't buy gas at credit card pumps [not a big deal
until you realize many Wyoming towns don't have attended gas stations due
to remoteness], etc - it lasted 8 hours), as they are a whole lot harder to
fix when broken.
With APRS, a D700 parked at the top of the hill is often all the
infrastructure that is needed. It won't function like the old network did,
but it could handle tactical communication for a reasonable area easily
enough.
------------------------------
Message: 4
Date: Wed, 4 Oct 2006 18:08:06 -0700
From: <scott_at_opentrac.org>
Subject: RE: [aprssig] first.aprs.net
>system and properly kills power to the whole room. Or someone
>accidentally snags the big red button on the way out the door
>(despite it being properly guarded). Or had the fire marshall tell
I'd always wondered if that button really worked, given how screwed up the
power situation was in our network control center. The alarm repair guy
answered that question - knocked the guard off and managed to jam it against
the button in the process of trying to catch it. Turns out it only worked
on 2/3 of the machines in the room. And then we realized that no one there
knew how to reset the system.
>running. Or had a generator oil pressure sensor fail 5 minutes after
>the generator starts. Etc...
Been there, too. The building housing all of the off-base connectivity
always had the worst generator.
Only fix for that sort of thing is multiple-site redundancy. That costs
money, though - and takes a lot of effort to do right.
Scott
N1VG
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Message: 5
Date: Wed, 4 Oct 2006 19:13:32 -0600
From: Joel Maslak <jmaslak-aprs_at_antelope.net>
Subject: Re: [aprssig] first.aprs.net
On Oct 4, 2006, at 7:08 PM, <scott_at_opentrac.org> wrote:
>Only fix for that sort of thing is multiple-site redundancy. That costs
>money, though - and takes a lot of effort to do right.
And always still a single point of failure, usually human in nature.
In fact, my experience is that I've had more failures that affected
end-users with multiple site systems than with non-redundant single-site
systems. Things failing over when they shouldn't, not failing over when
they should, etc.
------------------------------
Message: 6
Date: Wed, 4 Oct 2006 18:26:29 -0700
From: <scott_at_opentrac.org>
Subject: RE: [aprssig] first.aprs.net
>In fact, my experience is that I've had more failures that affected
>end-users with multiple site systems than with non-redundant single-
>site systems. Things failing over when they shouldn't, not failing
>over when they should, etc.
And that's exactly what I mean by requiring a lot of effort. You really
have to have the design and test procedures right to be sure it's going to
work. Too easy to miss some subtle DNS problem or failover logic error.
When I left my last job, I had to hand over a high-reliability clustered
system I'd maintained for years, originally migrated from VMS. There was no
way to get someone else up to speed on the system fast enough, so it was
restructured to use a single active server booting from a SAN, with an
identical machine as a cold standby. In case of a server failure, it'd just
be a matter of switching the SAN connections over. Not as slick as the
original setup, but much simpler to understand and maintain. I think
they've finally got it back in its proper configuration again.
The moral of the story is that you have to balance the complexity of your
high-reliability system against your tolerance for downtime and available
resources.
Scott
N1VG
------------------------------
Message: 7
Date: Wed, 4 Oct 2006 21:38:38 -0700 (PDT)
From: "Tyson S." <timbercutter_at_yahoo.com>
Subject: Re: [aprssig] low power 2 meter exciter needed
The Big Red Bee all ready makes an AFSK ready transmitter at 30 milliwatts.
http://www.bigredbee.com/BeeLineGPS.htm
--- Art <KY1K_at_verizon.net> wrote:
>I need a simple, low cost and relatively inexpensive exciter (single
>frequency) for 2 meters, and was wondering if users here might have
>any ideas. I want it to take an 18 Mhz quartz crystal input and
>output 10 to 30 milliwatts at 144 Mhz.
>
>It's for a stand alone 2 meter transmitter that can be used for
>trackers and weather station APRS.
>
>There are some user programmable oscillators that are suitable for
>clock drivers in microprocessors, they are not suitable, to much
>jitter and are not stable enough to stay on the same frequency.
>
>A PLL chip is ok, except that any chip I found takes a lot of support
>circuitry (outboard divide by N counters and/or vco's), and they all
>need a microprocessors to talk to the chip to determine it's divide
>by n value.
>
>Maxim has some low power transmitter chips, but they are unsuitable
>because the vco is built in and cannot oscillate at 2 meters (they
>will only oscillate from 300 to 500 Mhz)... Unfortunately, they did
>not bring provisions to the outside world for allowing the user to
>change the vco's frequency of operation.
>
>I'd rather not design multipliers myself, so I'm really hoping for a
>ready made module or a simple to use chip.
>
>Any ideas?
>
>Thanks,
>
>Art
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