From: rparratt@london.micrognosis.com (Richard Parratt)
Date: Thu, 12 Jan 95 01:43:37 PST
To: perobich@ingr.com
Subject: Re: Storm Signals
Message-ID: <9501120943.AA03267@pero>
MIME-Version: 1.0
Content-Type: text/plain


> 
> If I were the DOD, I would set the standard GPS default to selective
> availability. After all, with SA on military receivers can still get
> fine positioning data. If someone could come up with a good reason to
> turn SA off, great, but I wouldn't leave it on otherwise.
> 
> The scenarios concerning GPS-piloted Cessnas full of nasty stuff come
> to mind, especially vis-a-vis the North Koreans. They probably don't
> have accurate IRBMs but they certainly could cobble together a
> Learjet-based delivery system.

SA is effectively cancelled out by using differential GPS
(Using a correction transmitter to send out differences
between GPS as-reported position and actual position).

However, any 'home made cruise missile' would need to
be fairly slow moving and manoevring. One of the features
of p-Code is support for 'high-dynamic' vehicles.

I've been away from the navigation field for some years,
so others may know more. Does the Russian Glonass system
have SA?

--
Richard Parratt