[time-nuts] Important parameters for a GPS/GNSS antenna

[Attila Kinali]

On Thu, 7 May 2015 14:43:44 -0400
Tim Shoppa <tshoppa at gmail.com> wrote:

> Gotcha with modulating the PPS onto a RF carrier, is that for time
> resolution of 1 nanosecond, you would end up using a Gigahertz of bandwidth.

Not really. You are not doing detection in frequency space
or of an infintely sharp pulse. As such it is ok if you are
bandlimited. Then you just have to ensure that the risinge
edge (or whichever you detect) has always the same shape and
you detect always at the same level.

It is basically the same principle with which we get sup-ns resolution
with PPS pulses. The wire isn't good for a bandwidth of >1GHz, usually
much less than that (especially the connectors), but as the pulse does
not have a very steep edge, it does not need to. Insted the pulse
amplitude and the detection level are kept as constant as possible.

Of course, any variation in amplitude, detection level or noise
degrades the measurement considerably.

			Attila Kinali
-- 
< _av500_> phd is easy
< _av500_> getting dsl is hard