From: Roger J Jones <cyber@ibpinc.com>
Date: Sat, 7 Jun 1997 04:56:10 +0800
To: "'cypherpunks@cyberpass.net>
Subject: FW: TV Commercial
Message-ID: <01BC7290.D17E3E60@PC1901>
MIME-Version: 1.0
Content-Type: text/plain



Having spent a fair amount of time on the high seas on gray ships I found the following interesting in that:

1)  Back in WWII days Aldis lamps were a pretty good option.  Unless you had a submerged enemy sub in your convoy you would most likely notice anyone who could intercept your communications.  Since of course convoys could travel faster than submerged subs the exposure was also limited in time.  Add of course the fact that most of the messages were in code, frequently unique for a given transit.

2)  Consider the changes in today's environment:
a) Image intensifying lenses make over the horizon (cloud bounce) reception possible.
b) Subs can move faster underwater than most surface ships.
c) Satellites could pick up the light pulses - either directly (if low horizon) or reflectively (off the water)
d) I suppose that the right spectrum could also pick up the heat caused by the filament of the lamp.

Of course, since it now takes about 45 gizillion people on a ship to "sign out" a message for release, the only messages that go out over Aldis lamps are the signalmen swapping scuttlebutt and sea stories in the name of "on the job training"

"Fair winds and following seas!"
An old salt.

-----Original Message-----
From:	Bill Frantz [SMTP:frantz@netcom.com]
Sent:	Friday, June 06, 1997 11:13 AM
Subject:	Re: TV Commercial

 At 12:34 AM -0700 6/6/97, David Lucas wrote:
>It's a nice thought, but the image is all wrong. Two ships communicating
>via Aldis lamps (presumably, I haven't seen the ad) using Morse at a guess,
>isn't what I would call very secure communication.

Well, the Japanese managed to keep secure communications when sneeking up
on Pearl Harbor, and I assume they used something similar for ship-to-ship
communications.  Narrow beam, and everyone who can receive is in sight is
nice.