bob@evoria.net said:

Or just wait and see how well the location it finds matches your current data.

The Z3801A manual is easy to find and contains a good description of the SCPI
commands.  Yes, I think there is a way to load the location and bypass the
survey.  I think there is a slot in Satsat where you can type in commands by
hand.

You don't need Satsat.  You can talk to it from the command line.  On Linux,
for a Z3801A, I do things like:
ln -s /dev/ttyS2 /dev/hpgps1
stty -F /dev/hpgps1 19200 cs7 parodd parenb igncr
stty -F /dev/hpgps1 19200 oddp igncr -echo
On one window:
cat /dev/hpgps1
On another window:
echo -e ":ptime:tcode:format F2" > /dev/hpgps1
echo -e ":diag:gps:utc 1" > /dev/hpgps1 # Needs reboot?
echo -e ":SYSTEM:STATUS?" > /dev/hpgps1

fix for week wrap - maybe only works before survey

echo -e ":GPS:INIT:DATE 2011,12,26" > /dev/hpgps1

--
These are my opinions.  I hate spam.

(I do not understand why Yahoo responds to the list for some of you and for others it responds only to the sender.  This is a resend to the list.)

Hi Hal,
That should have been Satstat, and yeah, after looking through the Z3801 User's Guide, I decided to just let it play by itself.  It found the right date after it started acquiring sats, so I guess all is good.
I think I figured out why only the REF-0 unit was responding.  And that's because there are two units, and the one that's not active doesn't reply.  At the moment, REF-0 which is responding has the ON light lit, and REF-1 says it's in STBY.
So I think I finally have a better phase reference than the 10811 I've been using.  At least the phase plot against my GPSDO project is pretty stable over the last 2500 seconds, and a proper ADEV curve is starting to develop.  Unfortunately, I've been battling what I think is a thermal problem, so it could all fall over sometime tonight.  OTOH, the survey isn't complete, and I have no idea about the performance of this Z3812A during survey.
And thanks for the Linux ideas.

Bob
From: Hal Murray hmurray@megapathdsl.net
To: Bob Stewart bob@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com
Cc: hmurray@megapathdsl.net
Sent: Friday, October 24, 2014 10:55 PM
Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup

bob@evoria.net said:

Or just wait and see how well the location it finds matches your current data.

The Z3801A manual is easy to find and contains a good description of the SCPI
commands.  Yes, I think there is a way to load the location and bypass the
survey.  I think there is a slot in Satsat where you can type in commands by
hand.

You don't need Satsat.  You can talk to it from the command line.  On Linux,
for a Z3801A, I do things like:
  ln -s /dev/ttyS2 /dev/hpgps1
  stty -F /dev/hpgps1 19200 cs7 parodd parenb igncr
  stty -F /dev/hpgps1 19200 oddp igncr -echo
  On one window:
    cat /dev/hpgps1
On another window:
    echo -e ":ptime:tcode:format F2" > /dev/hpgps1
    echo -e ":diag:gps:utc 1" > /dev/hpgps1 # Needs reboot?
    echo -e ":SYSTEM:STATUS?" > /dev/hpgps1

fix for week wrap - maybe only works before survey

echo -e ":GPS:INIT:DATE 2011,12,26" > /dev/hpgps1

--
These are my opinions.  I hate spam.

Hi

Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit.

The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing.

Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is.

Bob

Hi Bob,
The thing is: I don't really need a frequency standard other than as a reference for my GPSDO project.  I'll have to look into pulling out that message every second to see if the correction makes it a suitable phase reference.  No, the nanosecond level probably isn't suitable for your needs, but I think it fits mine.  My target audience remains the hobbyist, not the professional.

It will be interesting, as it ages in, to see how it likes the antenna at the south window that it's sharing with my project.  If I don't see any glitches, it may be time to pull the wire through the attic, rather than through the window.  I guess I could also get some good information running it with the antenna in the attic for awhile.  But you do make a good point about power supplies.  Santa may bring a small UPS for Christmas to power this, my project, and the splitter.
At the very least, this gives me a lot of information about GPSDOs that I didn't have in the past.  And there's that EFC pin-out back near the OCXO that I could watch with my 3456A, to see what the dynamics are on a "real" GPSDO, once it ages in.

Bob
From: Bob Camp kb8tq@n1k.org
To: Bob Stewart bob@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Saturday, October 25, 2014 1:22 PM
Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup

Hi

Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit.

The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing.

Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is.

Bob

Hi

Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812.

The PPS output on these is not typically designed as a “smoothed’ time reference. The HP / Symmetricom design philosophy seems to have been that dropping or adding time was an ok thing to do. Your 90 ns to 50 ns change is a prefect example of this in action.

One simple experiment: Set up a divider on the 10 or 15 MHz output. A dead bug mounted PIC will do, there are many other alternatives. Compare that PPS to the PPS out of the device. If your divider works properly, it should give you a quick way to see if they are slipping the PPS relative to the OCXO.

Bob

These units are ideal for powering via a float charged lead acid battery.
Use two 12 volt / 7 AH batteries in series and adjust the regulated float
power supply to 28.0 volts. Be sure to use a diode from the supply to the
battery just in case the supply can't be back fed during a power fail.

Tom

----- Original Message -----
From: "Bob Camp" kb8tq@n1k.org
To: "Bob Stewart" bob@evoria.net
Cc: "Time Nuts" time-nuts@febo.com
Sent: Saturday, October 25, 2014 3:01 PM
Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup

Hi Bob,
The antenna is actually outside.  It's mounted to the eave just below the roof line.  It seems to be a better antenna than the one in the attic.  It's the best I can do at the moment.

I'll have to do a comparison of the PPS from this and the PPS from my LEA-6T.  I think they're reporting the phase offset of the 10MHz to the PPS, but as you say, I haven't measured it yet.

Bob

  From: Bob Camp <kb8tq@n1k.org>

To: Bob Stewart bob@evoria.net
Cc: Time Nuts time-nuts@febo.com
Sent: Saturday, October 25, 2014 2:01 PM
Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup

Hi

Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812.

The PPS output on these is not typically designed as a “smoothed’ time reference. The HP / Symmetricom design philosophy seems to have been that dropping or adding time was an ok thing to do. Your 90 ns to 50 ns change is a prefect example of this in action.

One simple experiment: Set up a divider on the 10 or 15 MHz output. A dead bug mounted PIC will do, there are many other alternatives. Compare that PPS to the PPS out of the device. If your divider works properly, it should give you a quick way to see if they are slipping the PPS relative to the OCXO.

Bob

Hi

The gotcha may be that they only slip time under unusual conditions. Warmup / settling in could be one such condition. It may take some detailed looking to spot it.

Bob

Might want to dial that back a bit.

Since 12V/7ah batteries are mentioned I am assuming standard small
gelcell units.

Proper float voltage for a deep cycle is lower than a SLI type, and
gellcell even lower.

Generally 13.6 - 13.8 would be the gellcell range, with 13.6 being right
on for long life use of small batteries.  Equalizing charge wold be 14

• 14.2.

Floating a small gelcell at 13.6 (27.2) v.s. 14 can mean the diff
between 12 - 24 months v.s. 5 - 7 years service life.

On 10/25/14, 11:39 AM, Tom Miller wrote:

Hi

Assuming the supplies are rated for a (fairy normal) 32V max, there is plenty of room to get everything arranged right. You might need to dig up a supply that is 28V nominal versus 24V nominal. The 10 or 15% adjust range likely will not quite get the 24V unit up where you would want it to be. The (say) 29V supply goes to one of your voting diodes and runs the unit when it’s off battery. The other voting diode goes to the top end of the battery stack. Your charger circuit puts what ever it wants on the battery to keep it happy. Yes, when you go on battery you loose .7 V (or less) due to the diode. If you want to get fancy, put a FET across the diode and eliminate the diode drop once everything gets going.

The bigger question is - how do you disconnect the battery after it’s done its thing for long enough? Deep discharge of the cells is not good for them either.

Yes this gets more complex by the minute …. where is that guy who was getting all preachy about keeping things simple :)…..

Bob

I really don't disagree with you. I did say run the supply at 28.0 and use a
diode off the supply to the battery. That would place the float voltage at
27.3 or so. Best would be to follow the manufacturers float service
recommendations. Ideally it should also be temperature compensated with
a -2.4 mV/°C slope. Not a problem with how we use these in the lab though.

And yes to get the longest run time, just power the main unit from the
battery as Bob suggested.

Now I am just waiting on some DB-9 connectors. I ran out of them and the
local RatShak went TU.

Tom

----- Original Message -----
From: "Christopher Brown" cbrown@woods.net
To: time-nuts@febo.com
Sent: Saturday, October 25, 2014 5:32 PM
Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup

use nickel-iron battery [Edison Accumulator] which is not sensitive to
deep discharge, over charge and last for min twenty years -
unfortunately it does not fit into the American business model --because
it last to long--so it is not produced in the US any more.
73
Alex
On 10/25/2014 5:30 PM, Bob Camp wrote:

Ahh, I read "adjust the regulated float power supply to 28 volts" as
including the protection diode as part of the PS and 28VDC straight to
batteries.

Have a half built setup like this on the bench right now.

36VDC unreg supply feeding 2 LM317 regulators with 5amp diodes on output.

Once floats a series pair of small 12v gelcells at 27.2 and the other a
single at 13.6

Need to get the enclosure and the AC filters done, they will be 24/7
powering 10811B type OCXO I want to setup as a standalone ref.

On 10/25/14, 5:54 PM, Tom Miller wrote:

Hi

Probably an important question to ask - how much current does this sub-species of the Z series pull off of 24V?

My guess would be it pulls a couple of watts  (say 6W) per box once the OCXO is warmed up. If so, that would be just under 1/4 A on the 28V supply and just over that as the battery crossed 24 V.

If you have the full dual box setup, that would be 1/2 A on battery. A 7A SLA would get you 14 hours of run time. At least around here, that’s a long (and unusual) outage. There’s nothing in the house (except the Honda generator) that will run that long in an outage. I’d be quite happy with a 1-2 AH setup that gives me 2 to 4 hours (or half that if my power estimates are bunk).

The 7AH’s are already dirt cheap. They make a ton of them. I’d save some money, but not a lot. The main thing I’d save would be space.

Bob