[time-nuts] Thunderbolt SV and AMU Signal levels

[John Franke]

Variation of +/- one count in the last digit is normal for any counter.  It 
is caused by a slight shift between the counter gate and the input signal. 
The longer the time between digit changes, the more stable the phase between 
the unknown and the counter gate.

John  WA4WDL

----- Original Message ----- 
From: "David Ackrill" <dave.g0dja at tiscali.co.uk>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Tuesday, July 22, 2008 7:14 PM
Subject: [time-nuts] Thunderbolt SV and AMU Signal levels


> Sorry to be a bore, but like any kid with a new toy I'm facinated by the
> changing values on the display...
>
> What do the values under SV and AMU mean?
>
> Maybe I should recognise them from other GPS satellite days, but they
> don't seem to be values that I remember.
>
> I'm sure it all means that they are to the north, south, east or west of
> here and to do with signal strength to my location or how good, or bad,
> the lock to the satellites is..  But, nothing that I can remember, to be
> honest...
>
> The 10MHz output seems, as far as my old Multifunction Counter is
> concerned, to be to 10.00000MHz within +/-0.00001 MHz.
>
> The display showing 10.00003 to 10.00004 MHz all evening.
>
> So, my guess is that my poor old counter is +/- 10Hz out, but that may
> be due to the age and non-calibration of my frequency counter over the
> years.
>
> Or... The Thunderbolt 10MHz output is moving up and down by 0.00001 MHz
> within a 10MHz band.
>
> This is where I start to get to grips with the spectrum analyser that a
> friend of mine lent to me.  I hope...
>
> Dave (G0DJA)
>
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