Reading the mail -- New Problem with GPS IIF-1?

An analyst at NOAA has noted anomalies with the orbit of the new GPS
IIF satellite. It has just gone into an eclipse season.

http://igscb.jpl.nasa.gov/pipermail/igsmail/2010/006313.html

--- CHAS

On 10-12-23 14:57 , HIPAR wrote:

What's special about that?

Don't they get eclipsed on a daily basis or even 2 times per day?

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gmail originated posts filtered due to spam.

On 12/30/10 4:20 PM, Alan Browne wrote:

GPS IIF-1 Satellite

Antenna Phase Center and Attitude Modeling
http://www.insidegnss.com/node/2243


Calculating the distances between satellites and user equipment is a
basic operation for GNSS positioning. More precisely, these ranges are
measured from the antenna phase centers of the satellites’ transmitting
antenna. However, phase centers vary among types and generations of
spacecraft and, further, the calculation requires knowledge of a
satellite’s orientation or attitude. A researcher at the European Space
Operations Center has analyzed the initial performance of the first GPS
Block IIF space vehicle and found some expected — and unexpected — results.

See: http://www.insidegnss.com/node/2243

wrote:


GPS satellites are in sunlight 24 hours per day except for during two
eclipse seasons per year. Then they are in the earth shadow twice per
day. When that happens, solar pressure cycles alter the orbit ever so
slightly. Temperature cycling has also been suspected of causing
minor stability problems with the GPS IIF atomic frequency standard.

--- CHAS

On 10.12.31 10:01 , HIPAR wrote:

Funny what I learn after decades of detailed knowledge about GPS! (user
segment mainly).

What is the length of the eclipse season for a given satellite? Should
be on the order of a few months, at least?

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