On Jan 19, 3:43*pm, Alan Browne
wrote:
On 2011.01.18 22:36 , macpacheco wrote:

CSACs might also make their way into all DPGS stations, improving
their calculated corrections. All current WAAS stations have a
standard Rb atomic clock (costs US$ 35000 each, lasting less than 10
yrs), replacing each Rb atomic clock with a triple redundant CSAC
facility will save a bundle on WAAS maintenance (with three clocks a
single faulty unit can be detected, excluded and marked for
replacement without stopping the station). Regular atomic clocks also
are temperature sensitive, requiring air conditioning, this CSAC can
handle temperatures from -10C to +50C.

The CSAC is not a deploy-able product. *It has to be integrated into a
receiver. *That, with design, integration, testing and certification
will drive up the cost considerably. *The $1500 will go to about $10 -
$15K as an educated guess.

For a fielded WAAS station, the -10°C may be unacceptable. *(There is
the military version which is likely more expensive, that goes lower,
-40°C).

--
gmail originated posts filtered due to spam.

From what I've seen all WAAS stations today are co-located with Air
traffic control centers. Perhaps one or two in alaska are stand alone.
Even -40C is probably not cold enough for Alaska, there it will need
some climatization.

Anything new will take years before the FAA is willing to touch it.
They are a lot more conservative even than the military. The current
WAAS network is operational, what's the need to replace things out of
the blue. By the time they start considering it, price will have
dropped considerably, probably when they perform the migration from
semi codeless to L1 CA+L5, probably circa 2020 (they stated that their
plan is an all or nothing thing, once they migrate, all WAAS reference
stations won't receive nor P(Y) nor L2C, L1 CA+L5 only, so they can't
migrate before L5 reaches FOC anyways, its a step backwards in my
opinion, but I digress) ... But as far as integration, atomic clocks
are a misnomer anyways, they are actually frequency sources, a timing
signal, or am I wrong ? I mean... they don't really keep time
(nanoseconds since a given date), they make a 10 MHz timing output
plus one or two other formats, that in turn is used not only to track
time, but also used for all kinds of very important receive/transmit
actual RF hardware (the more accurate clock available for the GPS RF
receive can improve receive SNR margins for instance and can transmit
a more precise signal for instance when generating the C band uplink
for the GEOs). A 10 MHz clock is a 10MHz clock, sure it will require a
ton of testing, but making it work, is it that expensive ?

Marcelo Pacheco - Not an electronics expert.