[time-nuts] FS: Brandywine GPS-4 - Qty: 7 available - Additional Specs

[Scott A Sybert]

Hi Guys...
 
A number of you have been inquiring about additional specifications on these units.    Here's what I've found.  It looks like it may address some of your questions.  I think this is all I'm going to be able to turn up on these units.  Most of the data we had on them is long gone.
 
Scott
 
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1.  Section 2.2.1: could you spec the min/max VOH/VOL and IOH/IOL
> >       of the PPS output.

Voh min 2.4V

Vol max 0.4V


> >
> >   2.  Section 2.2.2: the amplitude of the 10MHz is at least 1Vrms
> >       in 50ohm: please also spec a maximum.

        

1.5V RMS Max


> >
> >   3.  Section 2.2.3: could you spec the min/max VOH/VOL and IOH/IOL
> >       of the 19.6608MHz output.

50pf load

   Voh 4.5V min

   Vol max 0.4V

   Iol/Ioh ±25mA

 Load 50 ohms

   Voh 2.4V min

   Vol 0.4V max
> >
> >   4.  Section 2.2.3: could you spec the jitter and the wander of
> >       the 19.6608MHz output.  (I am concerned about the frequency
> >       variation over a 1-second duration.)

Short term stability

Square root of Allan Varience: 1x10-10, tau = 1 second

Phase jitter:  100ps


> >
> >   5.  Section 2.3.1: could you spec the min/max VIH/VIL and IIH/IIL
> >       of the Reset input.

Voh min 4.5V

Vol max 0.4V

Iol<0.1ma

Ioh 1mA max


> >
> >   6.  Section 2.7: I do not understand the open-collector pulled
> >       to ground, then the next line mentions a max pull-up voltage.
> >       Please clarify.

This is an output which is open collector, pull up through a 1K resistor to 5 volts.  "open collector pulled to ground" was an incorrecte statment.
> >
> >   7.  Section 2.7: there seems to be an inconsistency about the
> >       active level of the "Fault" pin: it is active low here, but
> >       active high in the table of section 2.9.
> >
> >   8.  Section 2.7: please define the criteria for the Fault output
> >       to be active.
> >
> >   9   Section 3.4: also a discrepancy between the text and the
> >       table about the active level of the Fault output.
> >

>   6.  Section 2.7: I do not understand the open-collector pulled
> >       to ground, then the next line mentions a max pull-up voltage.
> >       Please clarify. 

This is an output which is open collector, pull up through a 1K resistor to 5 volts.  "open collector pulled to ground" was an incorrect statement.
> >
> 

User connection is to COLLECTOR of transistor (via 100R internal protection).  The user can connect this collector through a resistive load to a positive voltage which has the maximum specified (with reference to pin 5 GND at connector).

 

When the GPS4 output is asserted (ie NO FAULT or TIME LOCKED) the transistor is turned ON sinking current from the user's positive supply through the users load and the 100R resistor inside the GPS4


> >   7.  Section 2.7: there seems to be an inconsistency about the
> >       active level of the "Fault" pin: it is active low here, but
> >       active high in the table of section 2.9.
> >

Pin 9 of the 9way Dtype socket is pulled LOW by the open collector transistor for NO FAULT.

The transistor is OFF in the case of a fault (which includes lack of power)


> >   8.  Section 2.7: please define the criteria for the Fault output
> >       to be active.
> >

 

There are 4 fault sources:-

 

Processor cannot run (watchdog asserts fault output)

 

8 hours of no reception of satellites (eg faulty antenna)

 

Frequency Error (GPS4 cannot control internal frequency standard (OCXO) to track reference 1pps from GPS)

 

DAC is near the end of its adjustment range (MAX 61440 MIN 4096)