[time-nuts] how good an oscillator do you need for a GPS simulator

[Magnus Danielson]

Hi Brooke,

On 12/18/2011 03:30 AM, Brooke Clarke wrote:
> Hi Magnus:
>
> Exactly. The main problem with the Transit system was that the receiver
> needed a Cs clock for the system to work at all. GPS removed that
> requirement.

Indeed. Most of that was due to the long observations times as I recall it.

The 4 satellite requirement of a normal navigation GPS receiver is there 
to allow for a complete (X, Y, Z, T) solution for a portable receiver 
which can't afford the weight and continuous power consumption of atomic 
references... at it's time of design.

> It's my understanding that a GPS receiver that uses a Cs clock has much
> more capability.

The main capability would be to either provide correction/ephemeris data 
(widely used) or to provide good navigation even under severe methods, 
as well as direct-Y locking.

Cheers,
Magnus