Hi,
On 04/12/2017 01:17 PM, Bob kb8tq wrote:
Hi
If you take a look at the standard weekly publications, the GPS system runs on
Rb’s.
There is always one sat that has a Cs turned on. That’s been true as long as
they
have been running the system. The simple answer for that choice is that the Rb’s
are easier to predict (better short term to medium term performance).
The Cs standards were originally on board to allow operation in the event that
the ground control
system was unable to upload to the constellation. There also was concern in the
80’s
about the reliability of the Rb’s. The configuration has stayed the same,
despite the
Rb’s being the main standard used.
Number of standards on board in the block IIF sats was 2 Rb’s and 2 Cs’s. That
is a
petty typical “redundant” approach.
For the block IIR they new cesium failed to get space-qualification, so
those birds only fly rubidium.
Cheers,
Magnus
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