[time-nuts] Re: 20210423: Introduction and Request for Spirent GSS4200 User Manual / Help

[Lux, Jim]

On 4/25/21 6:02 AM, Bob kb8tq wrote:
> Hi
>
> The thing that I find useful about a GPS simulator is it’s ability to calibrate the
> time delay through a GPS based system. In the case of a GPSDO, there may be
> things beyond the simple receiver delay that get into the mix. Getting the entire
> offset “picture” all at once is nice thing. Yes, that’s a Time Nutty way to look at it…..
>
> So far, I have not seen anybody extending this sort of calibration to the low cost
> SDR based devices. Without digging into the specific device, I’m not sure how
> well a “generic” calibration would do. Indeed, it might work quite well. Without
> actually doing it … no way to tell.
>
> So if anybody knows of the results of such an effort, I suspect it would be of
> interest to folks here on the list.
>
> Bob


A double difference kind of relative measurement might be useful - 
compare two (or three) GNSS receivers.  Then the absolute timing of the 
test source isn't as important.