[time-nuts] 20Hz p-p / 24 hours with a Mini-T
bruce.griffiths at xtra.co.nz
Fri Jan 9 01:51:28 EST 2009
Miguel Checa wrote:
> Hi group!
> I need some opinions, counsel, help, whatever you can send my way:
> I need to maintain the Mini-T within 20 Hz p-p in a 24 h period. I use
> T=450 and all is well until the thing starts to lose satellites one by
> one and goes into holdover and after a while, the VCO voltage jumps to
> the start value and with it the frequency (up to -150Hz).
> The antenna is not in a good place and it can't be moved, but if I
> restart the Mini-T, all satellites that were grayed out come alive and
> strong. Any clues?
20Hz is a fairly wide tolerance that one could easily maintain with a
good OCXO with periodic manual frequency adjustments of perhaps once per
If the Mini-T never sees a sufficient number of SVs uninterrupted for
somewhat longer than 450 sec then you need to reduce T to a value such
that sufficient SVs are seen for longer than T.
Do you have anyu idea of sky coverage and maximum observed SV track lenghts?
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