Chris,
The Z3816 has a few design short comings. In the circuit board pic the MTI
oscillator circuit board grounding is improved. Subsequently I opened and
modified the oven internally and added an extra oven feedthrough pin. The
issue is the oven heater current modulates the ground pin voltag
I saw a rather expensive GPS antenna made by one of the
big-name GPS survey equipment mfgrs that was mounted
on top of a 12 or 15 inch diameter disc about 3/4 inch thick.
Turns out that the disc is made of some sort of RF absorbent
foam covered by a weather-proofing coating of some sort.
If on
>I'd like to verify this myself in a similar Z3816A; can you show
>me how you got the 100 and 1,000 DAC step figures and also
>how you measured the 4 mV value? Do you also have a Z3801A
>you can measure?
The DAC numbers were intended to express the scale of the problem and were
rounded. Using a
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>How do you distinguish this effect from oven temperature variations due
>to finite thermal gain, particularly with a single oven OCXO?
>For small changes the effects are both linear.
Bruce many OXCO have an internal voltage r
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>Is the worry, then, about the minor ambient temperature related
>variations in steady-state oven current? Or something else?
Tom the problem is easy to observe by cooling the OXCO with a fan and
watching the EFC change.
I li
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>Date: Sun, 04 Nov 2007 10:24:59 -0500
>From: xaos <[EMAIL PROTECTED]>
>Subject: Re: [time-nuts] Fury Interface Board: 5MHz needed?
>To: Discussion of precise time and frequency measurement
>
>Message-ID: <[EMAIL PROTE
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Hi all,
I have been playing with a phase and frequency locked local oscillator in
my 3816A GPS receiver. The simple setup uses the OCXO output as an external
reference input to a HP 3325A and with a trivial mod to the VP GPS
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>thanks for the info. Not sure you can say 5 sample averages result in 1/5
>the error. I think you have to use 1/sqrt(5) if it's Gaussian noise. Well, a
>hanging bridge is hardly Gaussian, so maybe you are right.
I wondered ab
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>C) I don't believe the Z3801A has 100ps single shot resolution and accuracy
>(for resolution doesn't do anything without accuracy) until someone will
>prove it to me. And even then it would be wasted resolution since the GPS
>I made a hardware sawtooth remover a couple of years ago as an
>experiment, but where I used it I didn't seen much difference. I just
>checked again recently, but the sawtooth errors seem very small
>compared to overall instability, even for just an M12 to Rb at a
>fairly stable temperature. The
>Surely its better to detect the pseudorange instability in software (if
>one has access) rather than attenuating the signal from all SVs.
>Another option is to use multiple GPS antennae operating as a phased array.
>
>Bruce
Of course but I think that approach is part of sub nanosecond time tran
> >> Surely it would be much simpler (in principle at least) to just to add
> >> sufficient Gaussian phase noise to the GPS receiver clock so that
> >> potential coherence problems are virtually eliminated.
>
>
>The noise only really needs to be added to the PPS positioning
>algorithm/hardware.
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>
>From: Peter Schmelcher <[EMAIL PROTECTED]>
>Subject: Re: [time-nuts] GPS Phase locked Local Oscillator experiment
>Date: Sat, 10 Mar 2007 16:42:09 -0800
>Message-ID: <[EMAIL PROTECTED]>
>
> >
> > >Message: 2
> > >Da
>Wonder how the Z3816A would like a modified VP inside... Hmmm... a closed
>loop system, what are really the timeconstants relevant, to make sure it
>is stable?
That is where I am going. The UT+ oncore inside the Z3816A is a simple
crystal and easy to feed with the 3325A. I currently have an ong
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