Jim,
I guess I should also have mentioned that I want to synchronize events
across the rockets with those happening in our mission operations, and thus
need a common time source. Furthermore, this is currently just an
experiment, and is not safety or mission critical. We have other GPS units
on board that can track all the way to orbit, but they're used for
navigation, not time keeping. BTW, you can get oscillators that can
withstand >30, 000 gs of shock. The Q-Tech QT88 is one example.
-Kevin
----- Original Message -----
From: "jimlux" <jim...@earthlink.net>
To: <time-nuts@febo.com>
Sent: Wednesday, March 09, 2011 6:15 AM
Subject: Re: [time-nuts] Spacecraft Timekeeping
On 3/8/11 11:05 PM, Magnus Danielson wrote:
On 03/09/2011 06:08 AM, Kevin Watson wrote:
Hi All. Thanks for responding. There are quite a few GPS receivers that
will work outside of the usual commercial-grade GPS limitations, but I'm
not too sure I need such a receiver. As my application is to just
accuratly time-tag messages for a data recorder, my thinking is to allow
a ruggedized GPSDO to stabilize on the pad before launch, and then just
before launch force the GPSDO into holdover mode and act as the PTP
grandmaster for the onboard computers until we reach orbit. Once on
orbit I have other means to synchronize the PTP grandmaster.
Why carry the dead weight of something unusable in orbit.
Drop the receiver and antenna out of the equation and just provide a
timing signal on launch pad...
I'm going to guess that you want a GPS receiver on orbit for other reasons
(like to know where you are, if your IMU or star tracker dies)
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