[time-nuts] New Japanese GPS accuracy

Bob Camp lists at rtty.us
Wed Jan 5 17:53:50 UTC 2011


The same three satellites and crazy orbit thing is used by Sirius to
broadcast satellite radio in the US. It's perfectly optimized if you live in
a deep canyon (urban or otherwise) in Nebraska....

The figure 8 stuff would seem to be a lot better for moving data to a
defined footprint than for setting up a useful navigation constellation. 


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Magnus Danielson
Sent: Tuesday, January 04, 2011 10:15 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] New Japanese GPS accuracy

On 01/04/2011 07:39 PM, Joseph Gray wrote:
> No details on how the extra Japanese satellite is making it possible
> to get this accuracy.

This is the first bird for the QZSS system. The Quasi-Zenith orbit 
creates a deformed figure of 8 over the earth, and has a fairly low 
speed while being overhead Japan. This helps significantly in urban 
canyons in Japan.

Just following links from that article you get some info, but searching 
for QZSS should give plenty of material.

A good example where a three-bird setup causes local improvements. 
Australians should also be happy about it.


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