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Technology Stocks : Trimble Navigation
TRMB 67.88+0.4%Feb 2 3:59 PM EST
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To: Robert A. Sutherland who wrote (1829)11/12/1997 8:23:00 PM
From: Petz  Read Replies (2) of 3506
 
Robert Sutherland, RE: GPS jamming

What you say about military receivers being much more "jam resistant" is correct, although with enough power anything can be jammed. But it reminds me of something that hasn't been discussed here yet, the nature of Ashtech's proprietary technology for tracking the military P/Y code. This allows them to achieve much higher position accuracy in a differential GPS system by exploiting the military codes. However, it doesn't buy you much in a non-differential system for the next several years.

Basically what I want to say is that the design of the Ashtech P/Y code tracker is considered to be close to a US Security violation by many on the military side of GPS. It could be argued that Ashtech could not have designed its receivers without knowing classified information about the encryption used in GPS. BTW, Ashtech can't do anything about the time and position errors inserted into the GPS data stream, which is why I said their techniques really only help differential GPS, where these errors are eliminated by using a calibrated receiver location.

The post about the GPS jammer reminded me of this because its another example of quasi-legal equipment.

Petz
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