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Message no. 1
From: dbuehrer@****.org (David Buehrer)
Subject: Radar
Date: Wed, 14 Aug 1996 14:27:58 -0600 (MDT)
Tried to send this this morning but it bounced and then I
accidently deleted it :(

In response to a question about radar on sentry guns I
said: I think search radar pulses every three seconds or
so, targeting radar pulses almost continuously.

Someone else said: Pulses are measured in microseconds.

I think I used the wrong word.

Commercial radar *sweeps* 360 degrees about once every 3-5
seconds. Targeting radar sweeps a small arc in a much
shorter timespan. Does the military have search radar that
sweeps faster? How fast? I'm gonna use those sentry guns
in the near future and I want have answers for my players.

-David

/^\/^\/^\/^\/^\/^\/^\/^\ dbuehrer@****.org /^\/^\/^\/^\/^\/^\/^\/^\
"His thoughts tumbled in his head, making and breaking alliances like
underpants in a dryer without Cling Free."
~~~~~~http://www.geocities.com/TimesSquare/1068/homepage.htm~~~~~~~
Message no. 2
From: Jeffrey Riordan <JRIORDAN@***.gov>
Subject: Radar -Reply
Date: Thu, 15 Aug 1996 09:26:23 -0400
>>> David Buehrer <dbuehrer@****.org> 08/14/96
04:27pm >>>
<snip>

I think I used the wrong word.

Commercial radar *sweeps* 360 degrees about once
every 3-5 seconds. Targeting radar sweeps a small
arc in a much shorter timespan. Does the military
have search radar that sweeps faster? How fast? I'm
gonna use those sentry guns in the near future and I
want have answers for my players.

-David

<<<<<<<<<<<<<<<<<<<<
I actually assumed that since they rotate in a 360
degree pattern they could emitt and detect a radar
pulse in all directions at once and detect the return
bounce. I've no basis for this other than watching
"realistic style" movies from Hollywood such as Red
October etc... then again that was for sonar as
opposed to Radar. I also assumed these guns were
designed for smaller scale areas not to search
Kilometers of Air space but maybe 500 meters in the
general area.
As far as getting around the guns I would assume
that some sort of ECM package could do it. Even one
player I have brought along a RF white noise
generator that covers the portion of the spectrum used
by most Radar. It has limitations but in general it
prevents the gun from getting a lock on the targets at
the source of the generator at least by Radar pulse.
Sound/IR and Low light are something else completly.
Message no. 3
From: "Paul J. Adam" <shadowrn@********.demon.co.uk>
Subject: Re: Radar -Reply
Date: Thu, 15 Aug 1996 23:16:09 +0100
In message <s213015d.080@***.gov>, Jeffrey Riordan <JRIORDAN@***.gov>
writes
> I actually assumed that since they rotate in a 360
>degree pattern they could emitt and detect a radar
>pulse in all directions at once and detect the return
>bounce.

Sure, that gives you a range (on everything that reflects radar) but no
directionality. You need a steerable beam (or lots of them) to actually
detect something usefully. By 2050 this would be generated
electronically from a phased array, not a mechanically rotating aerial.

> As far as getting around the guns I would assume
>that some sort of ECM package could do it. Even one
>player I have brought along a RF white noise
>generator that covers the portion of the spectrum used
>by most Radar. It has limitations but in general it
>prevents the gun from getting a lock on the targets at
>the source of the generator at least by Radar pulse.

It also marks you perfectly as a target and is easily detectable. "Radar
whited out. Targeting source of jamming. Firing, maximum rate. Jamming
terminated."

Against many modern weapons, deploying jammers or other countermeasures
actually *improves* the chance of the weapon killing you.

--
"There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy."
Ambrose Bierce, "The Devil's Dictionary"
Paul J. Adam paul@********.demon.co.uk
Message no. 4
From: "Paul J. Adam" <shadowrn@********.demon.co.uk>
Subject: Re: Radar
Date: Wed, 14 Aug 1996 21:48:52 +0100
In message <9608142027.AA19986@******>, David Buehrer
<dbuehrer@****.org> writes
>In response to a question about radar on sentry guns I
>said: I think search radar pulses every three seconds or
>so, targeting radar pulses almost continuously.
>
>Someone else said: Pulses are measured in microseconds.
>
>I think I used the wrong word.
>
>Commercial radar *sweeps* 360 degrees about once every 3-5
>seconds. Targeting radar sweeps a small arc in a much
>shorter timespan. Does the military have search radar that
>sweeps faster? How fast? I'm gonna use those sentry guns
>in the near future and I want have answers for my players.

The Mark 23 TAS on the DD-963s sweeps three times a second. That's a
ship radar designed to detect low-flying aircraft/missiles or ships.

A phased-array radar, which doesn't have to rotate a mechanical aerial,
often won't 'sweep' so much as scan one beam around in search, while
using others to track interesting targets more or less continuously (the
AEGIS system uses 'track' beams interrogating the target about twenty
times a second, for instance).

The shorter the detection ranges involved, the faster the sweep rate has
to be. The E-2 and E-3 scan every ten seconds, but they're looking out
hundreds of miles.

--
"There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy."
Ambrose Bierce, "The Devil's Dictionary"
Paul J. Adam paul@********.demon.co.uk
Message no. 5
From: rhoded01@******.STCLOUD.MSUS.EDU (Ahzmandius)
Subject: Re: Radar -Reply
Date: Thu, 15 Aug 1996 14:15:14 -0600 (CST)
>>>> David Buehrer <dbuehrer@****.org> 08/14/96
>04:27pm >>>
><snip>
>
>I think I used the wrong word.
>
>Commercial radar *sweeps* 360 degrees about once
>every 3-5 seconds. Targeting radar sweeps a small
>arc in a much shorter timespan. Does the military
>have search radar that sweeps faster? How fast? I'm
>gonna use those sentry guns in the near future and I
>want have answers for my players.
>
>-David
>
><<<<<<<<<<<<<<<<<<<<
> I actually assumed that since they rotate in a 360
>degree pattern they could emitt and detect a radar
>pulse in all directions at once and detect the return
>bounce. I've no basis for this other than watching
>"realistic style" movies from Hollywood such as Red
>October etc... then again that was for sonar as
>opposed to Radar. I also assumed these guns were
>designed for smaller scale areas not to search
>Kilometers of Air space but maybe 500 meters in the
>general area.
> As far as getting around the guns I would assume
>that some sort of ECM package could do it. Even one
>player I have brought along a RF white noise
>generator that covers the portion of the spectrum used
>by most Radar. It has limitations but in general it
>prevents the gun from getting a lock on the targets at
>the source of the generator at least by Radar pulse.
>Sound/IR and Low light are something else completly.
>
Ok, the real trick is to get a high enough pulse repitition frequency (PRF),
then you can get a sweep of .3-.5 sec. A radar with a freq of 15000 and a
PRF of around 10000 can have a virtually unlimited sweep rate and a
resolution high enough to see a fly pass by, the danger is that a freq that
high will also have a near lethal radiation dose within 5-8 ft. The best ecm
for that would be either chaff or active jamming, or white noise, (that
the bad guys would be able to locate in a fairly short period of time, say 5
min.) The best bet is to launch chaff at the guns and wait for them to run
out of bullets, or dash by them in the dissarray.


Ahz
Message no. 6
From: rhoded01@******.STCLOUD.MSUS.EDU (Ahzmandius)
Subject: Re: Radar
Date: Wed, 14 Aug 1996 19:14:54 -0600 (CST)
>Tried to send this this morning but it bounced and then I
>accidently deleted it :(
>
>In response to a question about radar on sentry guns I
>said: I think search radar pulses every three seconds or
>so, targeting radar pulses almost continuously.
>
>Someone else said: Pulses are measured in microseconds.
>
>I think I used the wrong word.
>
>Commercial radar *sweeps* 360 degrees about once every 3-5
>seconds. Targeting radar sweeps a small arc in a much
>shorter timespan. Does the military have search radar that
>sweeps faster? How fast? I'm gonna use those sentry guns
>in the near future and I want have answers for my players.
>
>-David
>
I could go into a fifteen day lecture on the different types of radars,
scans, etc., I was an Electronic Warfare Technician in the USN for six
years. What I WILL tell you (and what I can tell you) is that radar varries
greatly depending on the function.

Scans: circular, used for air search, surface scan, a general purpose radar.
(sweep depends on range desired, remember that the pulses need only have to
have enough time to be emmitted and returned at the max range of th e
radar.) Bi-directional, used for misile guidence and aircraft ground scans.
Conical, fire control radars. Unidirectional, steady scans,etc. The best
resource for radars is "Jane's Book of Ships" or another such resource. If I
get into more, I will be getting into dangerous waters with classified and
unclasified data. I forget which is which. Sorry.

Dan Rhode, EW2, USN (retired)

Aka: Ahzmandius
Message no. 7
From: rhoded01@******.STCLOUD.MSUS.EDU (Ahzmandius)
Subject: Re: Radar
Date: Mon, 19 Aug 1996 18:18:53 -0600 (CST)
>The Mark 23 TAS on the DD-963s sweeps three times a second. That's a
>ship radar designed to detect low-flying aircraft/missiles or ships.
>
>A phased-array radar, which doesn't have to rotate a mechanical aerial,
>often won't 'sweep' so much as scan one beam around in search, while
>using others to track interesting targets more or less continuously (the
>AEGIS system uses 'track' beams interrogating the target about twenty
>times a second, for instance).
>
>The shorter the detection ranges involved, the faster the sweep rate has
>to be. The E-2 and E-3 scan every ten seconds, but they're looking out
>hundreds of miles.
>
>--
>"There are four kinds of homicide: felonious, excusable, justifiable and
>praiseworthy."
>Ambrose Bierce, "The Devil's Dictionary"
>Paul J. Adam paul@********.demon.co.uk
>
I am glad that you answered that and not me.....I might get in trouble :(

Ahz
Message no. 8
From: "Paul J. Adam" <shadowrn@********.demon.co.uk>
Subject: Re: Radar -Reply
Date: Tue, 20 Aug 1996 00:07:16 +0100
In message <01I8B355POEE0000IA@******.STCLOUD.MSUS.EDU>, Ahzmandius
<rhoded01@******.STCLOUD.MSUS.EDU> writes
>Ok, the real trick is to get a high enough pulse repitition frequency (PRF),
>then you can get a sweep of .3-.5 sec. A radar with a freq of 15000 and a
>PRF of around 10000 can have a virtually unlimited sweep rate and a
>resolution high enough to see a fly pass by, the danger is that a freq that
>high will also have a near lethal radiation dose within 5-8 ft. The best ecm
>for that would be either chaff or active jamming, or white noise, (that
>the bad guys would be able to locate in a fairly short period of time, say 5
>min.) The best bet is to launch chaff at the guns and wait for them to run
>out of bullets, or dash by them in the dissarray.

Problem with chaff - no real doppler. And I'd expect sentry-gun radar to
be millimetre-wave: we can already discriminate vehicles on MMW radar, a
sentry-gun could use that same effect to - if nothing else - sort
targets by weapons carried.

Any sort of noise jamming I'd be wary of simply because of the potential
for a fire-at-source mode on the gun: when jammed, DF it and hose it.
Kind of fatal for anyone carrying the jammer.

Ahzimandias knows EW, I know sonar (lightweight torpedo engineering) and
I have the same problems with classification he does: suffice it to
repeat that, with modern systems, simple countermeasures actually
_increase_ the chance of the system killing you.

--
"There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy."
Ambrose Bierce, "The Devil's Dictionary"
Paul J. Adam paul@********.demon.co.uk
Message no. 9
From: "Paul J. Adam" <shadowrn@********.demon.co.uk>
Subject: Re: Radar
Date: Tue, 20 Aug 1996 00:26:55 +0100
In message <01I8GWTMLCH20000IA@******.STCLOUD.MSUS.EDU>, Ahzmandius
<rhoded01@******.STCLOUD.MSUS.EDU> writes
>
>I am glad that you answered that and not me.....I might get in trouble :(

Read it in Friedman's US NAVAL WEAPONS and a few other places :)

Post to sci.military.naval for a year, while holding UK SECRET
clearance, and you get pretty good at the art of "the average of the
unclassified material". The worst thing is, you have to be careful even
endorsing a particular reference.

I talk freely about radar because my field is anti-submarine warfare,
and everything I got about above-water EW is open source: but I need to
tread very carefully when asked for a good reference on ASW, for
instance, because some open sources are better than others.

--
"There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy."
Ambrose Bierce, "The Devil's Dictionary"
Paul J. Adam paul@********.demon.co.uk
Message no. 10
From: rhoded01@******.STCLOUD.MSUS.EDU (Ahzmandius)
Subject: Re: Radar
Date: Tue, 20 Aug 1996 08:34:48 -0600 (CST)
>In message <01I8GWTMLCH20000IA@******.STCLOUD.MSUS.EDU>, Ahzmandius
><rhoded01@******.STCLOUD.MSUS.EDU> writes
>>
>>I am glad that you answered that and not me.....I might get in trouble :(
>
>Read it in Friedman's US NAVAL WEAPONS and a few other places :)
>
>Post to sci.military.naval for a year, while holding UK SECRET
>clearance, and you get pretty good at the art of "the average of the
>unclassified material". The worst thing is, you have to be careful even
>endorsing a particular reference.
>
>I talk freely about radar because my field is anti-submarine warfare,
>and everything I got about above-water EW is open source: but I need to
>tread very carefully when asked for a good reference on ASW, for
>instance, because some open sources are better than others.
>
>--
You speak my language! I hate watching movies like Under Seige for those
same reasons "That is wrong....but I can't tell you exactly why!" types of
situations. BTW, what are the UK fast attacks?

Ahz
Message no. 11
From: "Paul J. Adam" <shadowrn@********.demon.co.uk>
Subject: Re: Radar
Date: Tue, 20 Aug 1996 15:57:01 +0100
In message <01I8HQPTBXZC0000IA@******.STCLOUD.MSUS.EDU>, Ahzmandius
<rhoded01@******.STCLOUD.MSUS.EDU> writes
>>Post to sci.military.naval for a year, while holding UK SECRET
>>clearance, and you get pretty good at the art of "the average of the
>>unclassified material". The worst thing is, you have to be careful even
>>endorsing a particular reference.
>>
>>I talk freely about radar because my field is anti-submarine warfare,
>>and everything I got about above-water EW is open source: but I need to
>>tread very carefully when asked for a good reference on ASW, for
>>instance, because some open sources are better than others.
>>--
>You speak my language! I hate watching movies like Under Seige for those
>same reasons "That is wrong....but I can't tell you exactly why!" types of
>situations. BTW, what are the UK fast attacks?

Currently the T-boats (Trafalgar, Turbulent, Tireless, Torbay,
Trenchant) and the S-boats (Swiftsure, Sovereign, Superb, Sceptre,
Splendid, and a sixth I can never remember). The older Valiant,
Warspite, Courageous, Conqueror and Churchill might still be in service,
but I think V and W at least are leaving or have been decommisioned.

New class coming is the Batch 2 Trafalgars, probably to be the W-boats
and my money's on Warspite for the first.

--
"There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy."
Ambrose Bierce, "The Devil's Dictionary"
Paul J. Adam paul@********.demon.co.uk
Message no. 12
From: GRANITE <granite@**.net>
Subject: Re: Radar
Date: Thu, 22 Aug 1996 02:28:34 -0700
Ahzmandius wrote:

> I am glad that you answered that and not me.....I might get in trouble :(
> Yea, Me too..Those 70 or 80 years haven't passed yet for me to speak
freely on some of the stuff that
comes up...:)
-
> You speak my language! I hate watching movies like Under Seige for those
> same reasons...."That is wrong....but I can't tell you exactly why!" types
> of situations.
> Ahz-
I don't know about you but I say this one right after I had gotten back
from survival school..And the
part where all of the crew is being marched around by the terrorists gave
flash backs...I still cant put
a bag over my head...:)
I think about that evening every time that movie comes up in
conversation...
But yea..I know what you mean about hollywoods ideas of how things should
work and just how
wrong they are usually irks me too...I was in ELINT analyst for the
USAF..Some of that stuff sure
was fun..

--
-------------------------------GRANITE
=================================================================
Lord, Grant Me The Serinity To Accept The Things I Cannot Change,
The Courage To Change The Things I Can,
And The Wisdom To Hide The Bodies Of Those People I Had To Kill
Because They Pissed Me Off.
~~~~~~~~~~~~~~ShadowRunner's Serinity Prayer
Message no. 13
From: "Terry L. Amburgey" <xanth@********.uky.edu>
Subject: re:Radar
Date: Sat, 17 Aug 1996 11:10:38 -0400 (EDT)
While we're on the subject of radar...One of the local news stations
periodically points out that the big green blobs on the weather radar shown
is not actually rain but the result of humidity and then the weather dudes
gives a 2 second blurb about how the humidity 'bends' the beam so that the
radar picks up ground clutter. Personally I think the weather dude got his
meteorological training from a matchbook cover program so I don't know how
much credence to give it.

Is it true? Is military radar more well behaved? Are there shadowrun
implications? Thanks in advance. Terry

Terry L. Amburgey
Associate Professor of Management
College of Business and Economics
University of Kentucky
Lexington, KY 40506-0034
Phone: 606-257-7726
Fax: 606-257-3577
Message no. 14
From: "Paul J. Adam" <shadowrn@********.demon.co.uk>
Subject: Re: Radar
Date: Sat, 24 Aug 1996 22:17:14 +0100
In message <199608171510.LAA24526@********.cc.uky.edu>, "Terry L.
Amburgey" <xanth@********.uky.edu> writes
>While we're on the subject of radar...One of the local news stations
>periodically points out that the big green blobs on the weather radar shown
>is not actually rain but the result of humidity and then the weather dudes
>gives a 2 second blurb about how the humidity 'bends' the beam so that the
>radar picks up ground clutter. Personally I think the weather dude got his
>meteorological training from a matchbook cover program so I don't know how
>much credence to give it.

Sounds kind of iffy to me, too. AFAIK weather radar does actually see
weather. The effect described is called ducting, and does occur.

>Is it true? Is military radar more well behaved? Are there shadowrun
>implications? Thanks in advance. Terry

Ducting is a major problem at sea, where radar beams behave oddly and
unpredictably near the sea surface (combination of beam distortion, and
reflection off the surface, giving multiple paths to the target and very
confused range and speed readings). The Persian Gulf is particularly
notorious for this.

The implications include the reasoning behind sea-skimming missiles:
because they approach in the altitude most prone to ducting effects,
they are very hard to track accurately enough to shoot at.

There aren't too many implications for Shadowrun unless you (like our
campaign) occasionally have outbreaks of naval warfare :)

--
"There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy."
Ambrose Bierce, "The Devil's Dictionary"
Paul J. Adam paul@********.demon.co.uk

Further Reading

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