[LEAPSECS] Leap smear

[Richard B. Langley]

Full CNAV messages are not being broadcast yet since the current  
version of the ground control system doesn't support them. A few  
partial test frames have been transmitted by the first Block IIF  
satellite.

The current NAV messages provide the quasi-Keplerian orbit parameter  
values for computing satellite coordinates in the WGS 84 ECEF frame.  
In deriving the orbit parameters, the ground control system operators  
take into account Earth orientation, including UT1 and polar motion,  
so that the user doesn't have to.

-- Richard Langley

On 30-Sep-11, at 5:59 AM, Keith Winstein wrote:


> On Fri, 30 Sep 2011, mike cook wrote:

>

>> Le 30/09/2011 09:13, Keith Winstein a écrit :

>>> DUT1 gets 31 bits, including the sign, and is in units of 2^(-24)

>>> second. They also give a rate of change so it can be approximated to

>>> first order by the receiver.

>>

>> Have you got a reference for this Keith? The only info I could find  

>> is from Page 18 sub-frame 4 where the GPS-UTC delta is defined  

>> maybe the doc was incomplete . And as a bonus, do you know of any  

>> receivers which report it?

>

> Hi Mike,

>

> The 31-bit DUT1 is actually part of the new GPS CNAV navigation  

> message on L2. See IS-GPS-200E table 30-VIII. I'm not sure if they  

> have actually started transmitting it yet.

>

> The traditional GPS navigation message also sends ephemeris  

> parameters to convert from ECI of the satellite ephemerides to ECEF,  

> but I do not think DUT1 can necessarily be derived from these, since  

> each ephemeris seems to be transmitted in a different ECI frame.

>

> -Keith_______________________________________________

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| Richard B. Langley                            E-mail:  

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