[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...

GandalfG8 at aol.com GandalfG8 at aol.com
Thu Oct 23 15:09:54 EDT 2014


Hmmmm, that is interesting.
 
Reminds me somewhat of the pads on the Trimble/Nortel GPSTM modules  that 
allow connectors to be fitted for use of offboard oscillators.
These are beginning to sound more fascinating by the minute:-)
 
Regards
 
Nigel
GM8PZR
 
 
 
In a message dated 23/10/2014 20:00:22 GMT Daylight Time,  
bobdarby at triad.rr.com writes:

Also of  interest is the three pin connector behind the osc labeled Vref, 
Rtn, and  EFC. Present on both boards.  Manufacturing test input?

bob  darby

On 10/23/2014 1:19 PM, Bob Stewart wrote:
> My units came  in today.  What I got appears to be new-in-box.  It's 
probably the  only thing I'll ever get with a blue Agilent sticker on the box.   
=)  It has a yellow Symmetricom notice inside the box.
> The  circuit board appears to be the same on both units, but that says 
nothing  about the firmware, of course.  The REF-1 has an Oncore receiver 
labeled  TM-AB - whichever one that is, small parts to support it, and a TNC 
connector  for the GPS receiver.
>
> The REF-0  is missing everything  related to the receiver, and has an SMA 
for the 10MHz output in the space  where the REF-1 has the TNC along with a 
few extra small parts.  This is  a shared space with both SMA and TNC pads, 
though they don't seem to share the  same electrical path.  Since the SMA 
and TNC share the same physical  space, even if the 10MHz is available 
somewhere, you'd have to do some surgery  on the case before you could bring it 
out.  Probably by adding a hole in  the case for the GPS antenna and using the 
pad space for the  SMA.
>
> It will be a day or two before I have the bits to apply  power and 
connect an antenna.  So, that's what I know.  I'd probably  just break something 
if I tried to find and bring out the 10MHz, so I'll have  to leave that to 
someone else.  But, the appropriate signals need to get  between the boards, 
so I wonder what's on the Interface pins?  Maybe just  arbitration, 1PPS, and 
sawtooth comms?
> In my case, I do need the  10MHz, so I'm just as happy to have bought 
both units at this point.   Maybe, down the road, someone will come up with the 
mods to convert a REF-1  into a REF-0, and vice versa, unless the firmware 
prevents  that.
>
> Bob
>       From: GandalfG8---  via time-nuts <time-nuts at febo.com>
>   To:  time-nuts at febo.com
>   Sent: Tuesday, October 21, 2014 5:59  AM
>   Subject: Re: [time-nuts] Lucent KS-24361,  HP/Symmetricom Z3809A, 
Z3810A, Z3811A, Z3812...
>      
> It seems from the auction revision table that this seller has been  
offering
>   these for some time, so perhaps another "hidden"  gem:-), but it's  
perhaps
> also worth noting that if this system  functions on similar principles to
> earlier RFTG kit then the GPS  conditioning is only applied to the unit
> actually  containing the  GPS module, with the other unit intended as  a 
standby
> should the  first one fail.
>   
> In other words, unless the system  redundancy is really required most 
users
> would probably only need the  GPS based unit, or would at least be  better
> off buying two of  those for the same money that the "matched" pair  would
>  cost.
>   
> The only advantage, as far as I'm aware  anyway, of the non-GPS unit is 
that
>   it contains a 10MHz  output.
> However, Skip Withrow published modification details in  January 2013
> showing how straightforward it was to add the the 10MHz  output, to the
> RFTGm-II-XO module, the PCB location for the socket was  already 
available, so I
> would suspect it wouldn't be too difficult on  these either.
>   
> Regards
>    
> Nigel
> GM8PZR
>   
>    
> In a message dated 20/10/2014 05:53:29 GMT Daylight Time,
>  stewart.cobb at gmail.com writes:
>
> Fellow   time-nuts,
>
> This (long) post is a review of the HP/Symmetricom  Z3810A  (or Z3810AS)
> GPSDO system built for Lucent circa  2000.  I wrote it  because I looked
> for more information  before I bought one, and couldn't  find much.
> It's relevant  because (as of this writing), you can buy a full  system
> on the  usual auction site for about $150 plus shipping.  For  those  of
> you lamenting the dearth of cheap Thunderbolts, this looks  like  one of
> the best deals going.  The description of these  objects does  not
> include "GPSDO", so time-nuts may have missed  it.  Search for one  of
> the part numbers in the subject line  and you should find it.
>
> So  what is it?  It's a dual  GPSDO built by HP as a reference
> (Redundant  Frequency and Time  Generator, or RFTG) for a Lucent
> cell-phone base  station, built  to Lucent's spec KS-24361. Internally,
> it's a close cousin  of a  later-model Z3805A.  Externally, it looks to
> be almost a  drop-in  replacement for the earlier RFTG system built to
>  Lucent's spec  KS-24019.  That was a redundant system containing  one
> rubidium (LPRO,  in the one I have) and one OCXO in  two
> almost-identical boxes.  That  spec went through several  revisions with
> slightly different nameplates and  presumably  slightly different
> internals.  You can generally find one   or two examples on the auction
> site (search for RFTG or   KS-24019).
>
> This system is similar, but the two boxes each  contain a  Milliren
> (MTI) 260-0624-C 5.000MHz DOCXO, and neither  contains a  rubidium.  The
> Milliren DOXCO is the same one  used in the later models  of the HP
> Z3805A / 58503A.  It's a  very high-performance DOCXO, in the  same
> class as the legendary  HP 10811, and better than the one in  most
> surplus  Thunderbolts.  The 5 MHz output is multiplied up to 10  MHz  in
> at least one unit, and 15 MHz in both units.  I don't have  the  ability
> to measure phase noise on these outputs, but I'd be  interested to  see
> the results if someone could.
>
>  Nomenclature:  The Z3810AS  (there always seems to be an "S" at  the
> end) is a system consisting of the  Z3811A (the unit  containing a GPS
> receiver), the Z3812A (the unit with no  GPS  receiver), and the Z3809A
> (a stupid little interconnect cable).   The GPS receiver inside the
> Z3811A is a Motorola device, presumably  some  version of an OnCore.
> Where the Z3811A has a TNC GPS  antenna input, the  Z3812A has an SMA
> connector labeled "10MHz  TP".  That is indeed a 10  MHz output.  It
> comes active  as soon as power is applied to the unit,  and its
> frequency  follows the warmup curve of the OCXO.  The two units  have
>  identical PCBs (stuffed slightly differently), and I have no   doubt
> that someone can figure out how to add a 10 MHz output to  the  Z3811A
> as well.
>
> Operation:  From the  outside, these units are  broadly similar to
> earlier units in the  Lucent RFTG series. The (extremely  valuable)
> website run by  Didier, KO4BB, has a lot of information on  those
> earlier units,  much of which still applies here.  The purpose of  these
>  units was to provide a reliable source of frequency and  timing
>  information to the cell-site electronics.  The 15 MHz outputs   from
> both units were connected to a power combiner/splitter and  directed  to
> various parts of the transmitter.  The units  negotiate with each  other
> so that only one 15 MHz output is  active at a time.  The  outputs
> labeled "RS422/1PPS"  contained a 4800 baud (?) serial time code  as
> well as the PPS  signal, which were sent to the control  computer.
>
> Power  is applied to the connector labeled "+24VDC" and "P1",  in
>  exactly the same way as the earlier RFTG units. Apply +24V to pin   1
> and the other side of the power supply (GND or RTN) to pin 2.   In
> these units, that power supply goes directly to an isolated   Lucent
> DC/DC converter brick labeled "IN: DC 18-36, 1.9A".   Presumably  you
> can run both units with a 4-amp  supply.
>
> Once you have applied  power, connect the Z3809A  cable between the
> jacks labeled "INTERFACE J5" on  each  unit.  The earlier RFTG units
> used a special cable between  two  DE-9 connectors, and it mattered
> which end of the cable  connected to which  unit.  The interconnect for
> these units  is a high-density DE-15  connector (like a VGA plug).  The
>  Z3809A cable is so short that the  two units need to be stacked  one
> above the other, or the cable won't  reach.  It doesn't  seem to matter
> which end of the cable goes to which  unit.   I don't know whether it's
> a straight-through cable, or whether   you could use a VGA cable as a
> substitute.
>
> When you  apply power, all  the LEDs on the front panel will flash.   The
> "NO GPS" light will  continue flashing until you connect a  GPS antenna.
> Once it sees a  satellite, the light will stop  flashing and remain on.
> The unit will  conduct a self-survey for  several hours.  Eventually, if
> all is well,  the Z3812A  ("REF 0" on its front panel) will show one
> green "ON" light and   the Z3811A ("REF 1") will show one yellow "STBY"
> light.  This  means  that the Z3812A is actually transmitting its 15MHz
> output,  and the other  one is silently waiting to take over if it
>  fails.
>
> Most time-nuts  want to see more than a pretty  green light.  The old
> RFTG series  allowed you to hook up a  PC to the "RS422/PPS" port and
> peek under the hood  with a  diagnostic program.  The program is
> available on the KO4BB   website.  It is written for an old version of
> Windows, and I had  no  luck getting it to run under Windows 7.  It does
> run  under WINE (the  Windows emulator for Linux) on Ubuntu 12.04 LTS.
>  To use it, you need to  make an adapter cable to connect the  oddball
> RS-422 pinout to a  conventional PC RS-232 pinout.   The adapter cable
> looks like  this:
>
> RFTG   PC
>
> DE-9P   DE-9S
>
> 7 <----------> 5
>
> 8   <----------> 3
>
> 9 <----------> 2
>
>  (According to the  official specs, this is cheating, because  you're
> connecting the negative  side of the differential RS-422  signals to the
> RS-232, and ignoring the  positive side of the  differential signals.
> However, it's a standard hack,  and it's  worked every time I've tried
> it.)
>
> With that adapter,  you  can see the periodic timetag reports from the
> unit.   The RFTG program  will interpret these timetags when it starts
> up  in "normal mode".  However, when I try to use any of the  diagnostic
> features built into the  program, it crashes  WINE.  The timetag output
> was required for  compatibility,  but I suspect that HP didn't bother to
> implement the Lucent   diagnostics.
>
> Instead, they added a connector which is not on  the  previous RFTG
> series.  That connector is labeled,  logically enough,  "J8-DIAGNOSTIC".
> It too is wired with RS-422,  so you need to use the same  adapter cable
> as before.  Once  you do, you'll find that this connector  speaks the
> usual HP SCPI  command set (Hooray!).  I used the official  SATSTAT
> program  (again under WINE on 12.04 LTS), but I'm sure that  other
>  programs written for this command set will work as well.  The   default
> SATSTAT serial port settings of 9600-8-N-1 worked for   me.
>
> After about 24 hours, with a poorly-sited indoor GPS  antenna,  my
> system has converged to TFOM=3, FFOM=0 (the best  possible  numbers),
> and a "predicted 24-hour holdover  uncertainty" of 5.2  microseconds,
> which is not too shabby.   It found the correct day and  year without
> any assistance, so if  it has a "GPS week number rollover"  problem,
> it's still in the  future.  I don't currently have the ability  to
> compare the  10 MHz output to anything else.  Again, if someone  else
>  can, I'd be interested to see the results.
>
> Additional  Notes:  The parts on the boards all have date codes of 1998
> or  1999.  The  Motorola GPS receiver has a firmware label that  reads
> "02/04/00".  The  SCPI error logs inside the HP units  were virgin when
> I first got  them.  They had 84 and 94  power cycles, respectively.
> Before the GPS  receiver acquired  time, the error log timestamps read
> "2000-05-09  00:00:00", which  I interpret as a firmware release date.
>
> The PCB has an   interesting feature.  Next to each soldered-in pin of
> the  Milliren  OCXO is a single-pin socket soldered into the board.   I'm
> guessing  this was used in manufacturing, to temporarily  install a
> Milliren and  confirm that the system worked before  permanently
> soldering it in.  (At production prices, the Milliren  would have cost
> far more than the rest  of the PCB.)  You  might be able to use this in
> reverse, if you have a  set of  Millirens to test from another source.
>
> The Z3809A  interconnect  cable has three of the 15 pins on each end
> clipped  a bit shorter than the  rest.  Not so short that they won't
>  eventually make contact, but short  enough to make contact later  than
> the rest.  Don't know why, but it's  clearly  deliberate.  A lot of
> hot-plug connectors are built that  way,  including USB connectors.  I
> have no idea what the  pinout of the  interconnect is.
>
> The redundant system  slaves both DOCXOs to the same  GPS reference.
> Inside the GPS  loop bandwidth, the two oscillators will have  almost
> the same  frequency and will differ only by phase noise and  short-term
>  stability.  This is almost a perfect setup for  experimenting  with
> certain kinds of time-nut measurements, assuming someone   can figure
> out how to get 10MHz out of the Z3811A unit.  If you  then  command both
> units into holdover, you could measure  longer-term stability  as well.
>
> The units are described  as "new in factory sealed box".  After an
> archeological  investigation of the various strata of labels and  tape
> on the  boxes, I would say that's probably accurate.  My set seems   to
> have been shipped from the Agilent factory in Korea to  Symmetricom  in
> Sunnyvale, CA sometime in August, 2000, shortly  after it was  built,
> and remained untouched until I opened  it.  I'm guessing it was  built
> and saved as part of a  spares program for Lucent, and kept  until
> Lucent decided they  didn't need spares any more.
>
> I have no  connection with  the current seller of these units (or any
> other sellers,  for  that matter) except as a satisfied customer.  I
> think I'll  order  another set as a spare, before the feeding frenzy
>  hits.
>
> Request for  help:  Both the SatStat and RFTG  programs run under WINE
> on stock  Ubuntu 12.04 LTS (32-bit)  without any tricks or  special
> configuration.  Neither seems  to run under WINE on Ubuntu  14.04 LTS
> (64-bit). I am a WINE  novice.  Any hints from WINE experts  would be
>  appreciated.  Also, I've been able to run TimeLab under WINE,  but  I
> can't connect it to my USB-to-488 interface, so I can't take   data.  If
> anyone can tell me how to set that up, I'd be  extremely  grateful.
>
> Cheers!
> --Stu
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