[time-nuts] Thunderbolt - trouble locking with some types of antennas

jimlux jimlux at earthlink.net
Tue Aug 1 14:31:43 EDT 2017

On 8/1/17 11:11 AM, Didier Juges wrote:
> "The newer the receiver, the more horsepower in the silicon. In the case of
> GPS, that
> gives you more correlators to do DSP. The sensitivity improvement is a
> direct result
> of that. If you take a look at the guts of a TBolt, they date to the late
> 1990’s. That’s
> a long time in silicon years …."
> It seems that more correlators would speed up the time to first fix, not
> necessarily the sensitivity, particularly I do not see how it would
> directly affect the capability to stay locked when signal strength
> fluctuates?
> On the other hand, more correlators may help when there is multipath and a
> whole bunch of extraneous signals are fed into the receiver, so maybe the
> apparent lack of sensitivity is really the inability to see the signal from
> the chaff, not necessarily sensitivity in terms of noise figure.

There's also "more sophisticated correlators" and "more sophisticated 
tracking loops" that are enabled by more computational horsepower.  The 
days of "independent" PN tracking loops for each signal are probably 
long gone, and there's clever "aiding" of the loops by estimating the 
on-the-fly variations.

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