[time-nuts] HP Z3801A Question

[tomknox at nist.gov]

Hi Everyone;
Please excuse me, I am jumping in a little late. This Fury unit is  
interesting, Is the price reasonable? Which MTI oscillator do they  
use? the 5MHz 260-0504? To expand things a bit, how do the Fury,  
Z3801A, Z3805A, Z3811A, Z3816A, 58503A and 58503B compare?  I just  
picked up a Z3811A and plan to characterize it this weekend. If anyone  
is interested I will list results. It has the same 5MHz MTI 260-0624  
that the Z3805A has? Does anyone have specs for this version of the 260?
Best Wishes;
Thomas Knox




Quoting SAIDJACK at aol.com:

> Hello Ernie,
>
> Glad your HP is still working well.
>
> Well it seems you found out how well the Fury is working with an excellent
> OCXO :)
>
> The unit running in Mexico achieves similar performance with our standard
> double oven OCXO, see for example:
>
>    _http://resco.ucol.mx/Fury/gpsstat.htm_
> (http://resco.ucol.mx/Fury/gpsstat.htm)
>
> It has not jumped in several days, and the standard deviation is between
> 1.7ns to 1.8ns when it doesen't jump during the last 24 hours.
>
> Yes, the TI as displayed by GPSCon is much better than the HP  unit. I think
> this is mostly due to the much better GPS receiver in the Fury,  since the
> OCXO of the HP unit is extremely good.
>
> Tom and I had discussions about this being caused by the small  sawtooth
> low-pass filtering we do on the TI intervall (Z3801A does the same  thing,
> otherwise you would see the full GPS Sawtooth). The theory was that  
> this  was what
> was causing the Fury to be so much better on GPSCon.
>
> To check this, we modified the firmware to completely remove this sawtooth
> filtering, and output the raw data instead, with all the nasty sawtooth
> artifacts on it.
>
> This did not change the result much, I think the max range went from  +/-10ns
> to +/-15ns if I remember correctly.
>
> So even if we display true raw capture data, we are still significantly
> better than the Z3801A which displays low-pass sawtooth filtered data.
>
> I think this can mostly be attributed to the extremely good  performance of
> the M12M GPS compared to the Oncore GPS in the HP unit.
>
> Also, I think you will see that your HP unit will get better over time, as
> the Crystal retraces and ages over the next weeks, and the control voltage
> changes will hopefully get to be smaller and smaller on your unit.
>
> bye,
> Said
>
>
> In a message dated 11/13/2008 14:38:57 Pacific Standard Time,
> ernieperes at aol.com writes:
>
> But both  unit , the HP and the FURY board running under the same
> software  simultaneously / GPS Con / and I was mentioning the same small
> "windows"  TI to GPS, and the FURY displays much better figures then
> HP.....but  probably each units gives out / display / different
> data??????
> Also the  graphic display / BLUE / on the FURY board the max ampl
> between +2,2nsec  and -2,0nsec sometimes +0,7nsec ,
> -1,7nsec...
> the HP unit never goes  under +15nsec and -20nsec...... almost 10 times
> worse.....
> Anyhow I am  happy because it seems to me that the HP is still OK after
> 3 years of  sleep.....
>
> Rgsa Ernie.
>
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