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

Bob Camp kb8tq at n1k.org
Wed Nov 5 07:41:39 EST 2014


On a “real” Ref-0 / Ref-1 combo, the Lucent status message (RS-422 / PPS port) shows which device the string is coming from. This is independent of their status bits. Previous digging into similar units shows the same thing on earlier Lucent GPSDO’s. All the details are buried (200 posts back according to some ..) in one of my previous posts.I do not have anything on the diag port, so I don’t know what it says. 

Looking at the few unknown pins / pairs on the 15 pin connector, I’m guessing that one of them might be high or low depending on it being a Ref-0 or Ref-1. I’m also guessing that the pair on pin 15 is serial both ways. At this point my guessing average is not to good on these parts. I’m not really expecting that it will improve. Figuring out what the last few pairs do would be a nice thing. 


> On Nov 5, 2014, at 7:20 AM, GandalfG8--- via time-nuts <time-nuts at febo.com> wrote:
> For what it's worth, here's what happened when I linked two Ref-1 units  
> together....
> One was fitted with it's GPS module as normal, I'll call this Ref-1.
> The other was as normal other than having it's GPS module removed, I'll  
> call this Ref-1-0.
> The link cable was around 15 inches long and wired 1-15, 2-14, etc, using  
> standard 15 way high density plugs.
> BTW, whereas shortened pins have been used in the past to ensure safe power 
> up sequences I'm pretty sure that on the Z3809A cable it's perhaps a  
> precaution to reduce the risk of bringing down the base station when hot  
> swapping.
> I've noticed that removing my "faker" plug once a stand alone Ref-1 is  up 
> and running starts to flash the Standby light but doesn't otherwise inhibit  
> operation, the 15MHz and 1PPS outputs remain available. I don't know how 
> long  this might continue but the system obviously responds differently once  
> fully booted to when it's first powered and I suspect the use of shortened  
> pins could be related.
> Anyway, back to the two linked....
> At power up both go through the flashing light sequence, then...
> Ref-1-0 -- "No GPS" - Flashing, "Fault" - Solid
> Ref-1 ------"No GPS" - Solid, "Fault" - Solid
> After the boot period finishes.....
> Ref-1-0 -- "No GPS" - Flashing, "Fault" - Solid
> Ref-1 ------"Standby" - Solid, all other lights off.
> Both units will talk via the J8 diagnostics port as soon as powered up but  
> Ref-1-0 behaves just as one would expect if the GPS module is removed, and 
> it  doesn't seem to be relaying any data from the Ref-1 unit, whilst  Ref-1 
> shows what looks to be a normal acquisition sequence, the onset of  
> conditioning, and a self survey
> At no time is there a 15MHz or 1PPS output available from either  unit.
> Although it's been conjectured that the firmware is identical in the Z3811A 
> and Z3812A, and the Prom markings certainly seem to confirm this, it would 
> also  seem that there must be something that tells the unit what it is, 
> either by a  firmware difference somewhere after all or perhaps a link on the 
> board  somewhere.
> This isn't just based on my not very successful experiment, although the  
> results are no great surprise:-), but my Ref-1 units always report  
> themselves to monitoring software as a "Z3811A Secondary Receiver".
> Based on this am I correct in thinking that a standard Ref-0 would report  
> as a "Z3812A Primary Receiver"?
> If so it has to get this information from somewhere.
> Regards
> Nigel
> In a message dated 04/11/2014 09:38:25 GMT Standard Time,  
> stewart.cobb at gmail.com writes:
> A wiring  diagram of the Z3809A cable interconnect cable was published
> earlier on  this list.  That information appears to be incorrect.  The
> cable  is actually wired pin 1 to pin 15, pin 2 to pin 14, etc.
> Another way to  describe it is that for each wire in the cable, the pin
> numbers on each end  of the cable add up to 16.
> A mated pair of these units is running in my  lab with a scratch-built
> interconnect cable following the above  rules.  This scratch-built
> cable allowed access to the interconnect  signals while the system was
> operating happily.  No lights were lit  except the green ON light on
> the Ref-0 unit (Z3812A, no GPS) and the yellow  STBY light on the Ref-1
> unit (Z3911A with GPS receiver).  The  following signals were observed
> on the interconnect (pin numbers given for  the J5 interconnect socket
> on the Ref-1 unit):
> Pin 1:  9600  baud serial data (described below)
> Pin 2:  logic low  (0.11V)
> Pin 3:  Ground (0.00V)  Presence detect? (see  below)
> Pin 4:  logic high (4.79V)
> Pin 5:  inverted  Motorola PPS, high (5V) for 800ms, low for 200ms
> Pin 6: "17 / 23 dBm"  signal from Ref-0 unit (see below)
> Pin 7:  logic high  (4.48V)
> Pin 8:  Ground (0.00V)
> Pin 9:  logic low  (0.11V)
> Pin 10: "17 / 23 dBm" signal from Ref-1 unit (see  below)
> Pin 11:  inverted PPS, low 400us, high (5V)  otherwise
> Pin 12:  logic low (0.12V)
> Pin 13:  Ground  (0.00V)
> Pin 14:  logic low (0.08V)
> Pin 15:  logic high  (4.78V)
> Pins 3, 8, and 13 appear to be firmly connected to  Ground.  (Note that
> these are the three pins which are clipped short  on the HP
> interconnect cable.)  On an unpowered, disconnected box  (either Ref-0
> or Ref-1), pins 8 and 13 are connected to Ground (low  resistance) and
> pin 3 is high impedance.  Presumably pin 3 on each box  (connected to
> the grounded pin 13 on the other box) is used to sense the  presence of
> the other box and/or the interconnect cable.
> The timing  of the PPS signal on pin 11 matches precisely the timing of
> the PPS signal  available on pins 1 and 6 of J6 (RS422/PPS) on the
> active Ref-0 unit.   Presumably this signal is coming across the cable
> from the Ref-0  unit.
> Note: when the system is coming up from a cold start, SatStat on  the
> unit with the GPS receiver (Ref-1) will show "[Ext 1PPS valid]" in  the
> space where it shows "[GPS 1PPS valid]" after the survey is  complete.
> It appears that the Ref-1 unit timing system is locking its  oscillator
> to the PPS coming from the Ref-0 unit during this  time.
> The timing of the PPS signal on pin 5 matches the timing of the  PPS
> output described in the Motorola OnCore manual.  Presumably  this
> signal is sourced by the Ref-1 unit to allow the Ref-0 unit to lock  to
> GPS.  The edges of this PPS signal look very dirty compared to  the
> signal on pin 11.  This may be an artifact of the homemade cable  used
> for this experiment.  The HP cable clearly has an overall  shield
> (visible through the cable sheath) and may have internal coax  or
> twisted pair for these PPS signals.
> When pin 5 and pin 11 are  observed together, the usual GPS sawtooth
> pattern is  evident.
> Someone discovered earlier that the both units will blink  their green
> ON lights if the front-panel switch on either unit is set to 23  dBm
> vice the normal 17.  Obviously each unit can communicate its  switch
> status to the other unit.  They use pins 6 and 10 to do  that.  Pin 10
> (on the Ref-1 unit) is high (~5V)  if the switch on  the Ref-1 unit is
> in the 17 dBm position, and low in the 23 dBm position.  Pin 6 (on the
> Ref-1 unit) gives the same indications for the switch on the  Ref-0
> unit.
> The serial data on pin 1 is transmitted at 9600 baud,  with a burst of
> data every second.  The signal idles at logic low  (near 0V) and rises
> to logic high (near 5V) during the burst.  This  may be the standard
> for TTL (not RS-232) transmission of serial data, or it  may be
> inverted.  The first few characters of one burst were  hand-decoded
> from a scope trace as 0x40, 0x40, 0x45, 0x61, 0x0B, or ASCII  "@@Ea".
> This appears to be the Motorola Oncore binary data format,  although
> "Ea" does not appear to be a valid Motorola command or  response.
> Perhaps the hand-decoding was in error.
> One can use  SatStat, talking to the Ref-0 (non-GPS) box, to issue
> queries and commands  to the GPS receiver.  The results are
> inconsistent, but it seems that  at least some of the queries get
> through and trigger responses.  If  the Ref-0 box is actually talking
> to the GPS receiver, it must be doing so  through the interconnect
> cable.  The specific wire in the cable used  for this (if any) has not
> yet been identified.
> An earlier post  speculated that the computer in each unit only had two
> UARTs.  This  does not seem possible.  Clearly each unit uses one UART
> to  communicate with the J8 diagnostic port.  The Ref-1 unit needs
> another  UART to communicate with the GPS receiver. And both units need
> to be able  to transmit the legacy Lucent timecode message out the J6
> (RS422/1PPS)  port.  Perhaps there is a transmit-only UART coded into
> the FPGA, or  perhaps one of the UARTs is timeshared with the Lucent
> message, or perhaps  there is another UART chip hidden somewhere on the
> board.
> It seems  unlikely that the two units are sending serial data to each
> other.   (No such data was observed on the interconnect.)  Instead,
> they appear  to communicate their state to each other by means of logic
> levels on  various pins of the cable.  The logic functions of pins 6
> and 10 have  already been identified.  Further research is  needed.
> Cheers!
> --Stu
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