[time-nuts] Re: Effect of temperature on cheap puck style GNSS antennas?

[Matthias Welwarsky]

Hi,

attached for illustration purposes, a screenshot of the effect.

TIC is the error against the GNSS, DAC is the DAC output (blue), PI integrator 
state (green), PI controller output (orange). The DAC output is offset from 
the controller output due to temperature compenation.

BR,
Matthias 

On Donnerstag, 12. Mai 2022 08:50:56 CEST Matthias Welwarsky wrote:
> Dear list members,
> 
> My DIY GPSDO has a rather well defined dependence to the environmental
> temperature, which correlates almost linearly with a frequency shift of the
> OCXO. However, at times I see the error against the GNSS reference
> increasing with its case temperature not warranting such effect.
> 
> My antenna is one of those cheap, magnetic, active antennas you'd put on a
> car roof. It's facing south and has full exposure to the sun, obviously.
> 
> During sunrise I see the TIC error increasing 20ns-30ns over lets say 2000
> seconds. The GPSDO case temperature rises, too, during that time as the room
> temperature increases, but it is only by 0.3°C.
> 
> I'm wondering if the temperature of the antenna, which of course rises much
> faster than the room temperature, can have an effect of this magnitude?
> 
> Best regards,
> Matthias
> 
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