[time-nuts] Lucent KS-24361 GPSDO arrived today several questions
GandalfG8 at aol.com
GandalfG8 at aol.com
Fri Nov 7 04:03:01 EST 2014
Very many thanks for the prod re the Diagnostic port.
Considering the other GPS kit I talk to using Hyperterminal and the like,
often because there's no other option, I don't know why it's never occurred
to me to do the same with the Z3801As and now these......
and any rude suggestions as to why will just be politely ignored:-)
It's not that I don't have access to the command set, but I suspect that
twelve years or so ago, totally green when it came to GPSDOs and with my
first Z3801A to play with, I was just grateful to find SatStat, and eventually
some nice commercial options, and never gave it a thought after that,
Anyway, I've just switched my Z3811A comms over to Hyperterminal and tried
the :SYST:STAT? command for starters.
That's obviously what SatStat uses to generate it's front page, although it
is continuously updated with SatStat, and we do have contact, and
something else to play with:-)
In a message dated 07/11/2014 00:07:56 GMT Standard Time, kb8tq at n1k.org
Ok, I got to spend a little quality time with my pair today. I mostly
poked at the Diag port with a terminal program.
Both of the units seem talk over the Diag port regardless of the mode they
are in (master / slave / fault ). Both respond to a sub-set of the Z3801
SCPI commands (= not all commands work). There are a few enhancements where
a query to a “node” gives a reply (which it should not if it’s “node only”
). All of it works ok at 9600 baud 8N1. All of it comes back with an error
message (E-xxx) after a valid command response. It may not like the
terminal program sending cr/lf or something like that.
By far the most useful thing to type is :SYST:STAT?
That executes the system:status request and gives you a nice full screen
of information. It shows you about 95% of the useful information all on one
page. About the only major thing missing is the DAC value. That’s available
with another command out of the Z3801 list. It does take a while to
compose and transmit the screen, so it’s not the best way to to this forever and
The data from the request is the same on both boxes. Same everything
except one shows as standby etc. The interesting details are things like
elevation mask and cable delay. Why interesting? You can set them with discrete
commands. You can also query the data with the same commands to make sure the
box “took” what you sent.
This allows experimentation with changing the elevation mask on each box
(or just simply doing a discrete query for the mask on each box). The Ref-0
/ slave will happily change things around with discrete commands. None of
them are reflected in the :SYST:STAT? listing on the Ref-0 or Ref-1. When
you look at the Ref-1 / gps box, it’s discrete query information matches the
:SYST:STAT? screen on both boxes. When you change things on the Ref-1 box
both screens follow that data.
When you pull the antenna on the gps box, it immediately (almost) goes
into gps fault led flashing mode. The slave box happily sits there for a while
(say a minute) with it’s gps led saying all is well. When you plug the
antenna back in, the process is reversed. The gps box goes out of flash mode
right away. The led goes out in a bit. The led on the slave box does not
follow for a minute or so.
All of this suggests to me that the Ref-0 / slave does not talk back to
the other box via serial. It also suggests to me that all it “sees” from the
Ref-1/gps box are the duplicates of the serial string out of the Motorola
gps module. The Ref-0 just figures out what’s happening by watching those
strings as they roll by.
Hope that makes sense….
If that’s all true, it should be “easy” to put dummy gps sentences into
the Ref-0 interface port and a pps from something else. Once it sees stuff
that it likes, it will start locking up to that pps. Cheap micro and just
about any modern gps = fancy new GPSDO. Quick / easy / not much work. A
little more complex if you decide to translate sawtooth data. That of course
assumes these boxes do anything with sawtooth ...
> On Nov 6, 2014, at 7:52 AM, GandalfG8--- via time-nuts
<time-nuts at febo.com> wrote:
> Hi Bob
> I view the master/slave situation the same way you do, but only
> because Lucent effectively sets things up the other way round so just
> wanted to be sure which way Paul was considering it.
> As regards, the "faking", yes, a single 15 way plug containing just a
> and a resistor is exactly what I use now.
> I realise the RS422 fudge isn't ideal but certainly very handy for some
> quick tests.
> I've got two or three RS422 PCI interfaces but hadn't previously had any
> spare slots, now I've got a couple of lovely Magma 13 way PCI expansion
> but need to hack them about so the ports are at the front.
> Whoever decided rack mount PC kit should be built with all the
> at the rear must have been really nuts, and it was too long ago to use
> "corridors" of racks as a viable excuse, someone somewhere just fitted
> desk top style cases and left the rest of us to get on with it..
> One of the best things I ever did was to buy a pair of "back to front"
> rackmount PC cases with all ports and cards available at the front,
> now I want everything else to match, and most test gear has just the
> All good fun, and certainly never a dull moment:-)
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