Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Magnus Danielson]

Hi,

The J06 P-59992A time interval calibrator is not only there to calibrate 
time offsets, but also offsets in trigger point. HP has a nice patent 
which describes it all.


I also got one, found it on ebay.

Cheers,
Magnus

On 07/09/2017 01:18 AM, Bob kb8tq wrote:

Hi

Good means whatever the 5313x needs for calibration. If that is four signals 
that are
crossing zero within < 10 ps of the “correct time” then that is the definition 
of good in this case.

Rise time delay, fall time delay are rarely the same in logic gates. 
Propagation inside a chip to
point A may well be different by nanoseconds relative to the propagation to a 
very similar
point B. All of that would mess up a signal that *might* need to be 50/50 to 
within 10 ps  or
a second signal that must cross zero half way in-between (also to within 10 ps).

If you want to have a lot of fun with this, pull out the timing analysis tool 
for your favorite
FPGA and start fiddling around.

Bob


On Jul 8, 2017, at 5:53 PM, Hal Murray  wrote:


t...@leapsecond.com said:

The PIC dividers are good to a couple ps. I suspect the larger issue is the
PCB and wiring design.


What does "good" mean?

I'd expect the variations due to power or temperature would be easy to
measure.

Delay through classic CMOS is linear with absolute temperature and inverse
linear with supply voltage.

The classic way to get time-nuts level noise on FPGA outputs is to wiggle a
nearby pin.   That shouldn't be a problem with a dedicated PIC but would
probably show up if you are generating multiple frequencies.


--
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Orin Eman]

FWIW, the "Theory" section here may help:

http://www.g8wrb.org/data///HP/Better_than_100_ps_Accuracy_in_HP_5370B_Time_Interval_Measurements_Through_Bias_Error_Reduction.pdf

Phase errors through the splitters seem to be taken into account.

The J06-59992A manual merely claims 100ps absolute accuracy is possible
with the 5370A/B.



On Sat, Jul 8, 2017 at 7:48 PM, Bob kb8tq  wrote:

> Hi
>
> Based on a quick read of the use of the device, they seem to be relying on
> it to be << 100 ps
> off from “ideal”.  How much it being non-ideal matters …. not clear. If
> you are correcting for various errors
> and eliminating both unknown source errors and destination errors it
> likely gets messy.
>
> Bob
>
> > On Jul 8, 2017, at 9:14 PM, Tom Van Baak  wrote:
> >
> > I knew we had talked about this before:
> > https://www.febo.com/pipermail/time-nuts/2006-August/021649.html
> >
> > The J06-59992A manual, schematic, app note, and patent are here:
> > http://rubidium.dyndns.org/~magnus/instruments/hp/J06-59992A/
> >
> > It was designed for the hp 5370 (20 ps) so perhaps the tolerances are
> less stringent if only used for hp 53132 (150 ps). Maybe one of you RF guys
> can tell from the schematic?
> >
> > Mark writes:
> >> Yes, they do show up...  but usually for big-ish bucks.   I want to
> build a small affordable replacement that anybody with a 531xx can have.
> >
> > I don't recall them being expensive at all, just unusual. But making a
> modern one for time nuts is a great idea -- both 5370 and 53131/53132
> users. Also, when someone gets around to creating a smart analog front-end
> to John's TAPR TICC board, your 59992A clone will come in handy.
> >
> > Note also this recent document by Bill Riley:
> >
> > http://www.stable32.com/A%20High-Resolution%20Time%
> 20Interval%20Counter%20Using%20the%20TAPR%20TADD-2%20and%
> 20TICC%20Modules.pdf
> >
> > Hal writes:
> >> What does "good" mean?
> >> I'd expect the variations due to power or temperature would be easy to
> measure.
> >> Delay through classic CMOS is linear with absolute temperature and
> inverse linear with supply voltage.
> >
> > When John created the TAPR TADD-2-mini board I tested the jitter using a
> TimePod (integrated phase noise mode). I'm looking for the web page or
> email now, but I recall it was under 2 ps. This is partly due to the fact
> that the PIC 12F is a fully synchronous MCU; no tricks with double clock
> edges or PLL's.
> >
> > /tvb
> >
> >
> > - Original Message -
> > From: "Bruce Griffiths" 
> > To: "Mark Sims" ; "Discussion of precise time and
> frequency measurement" 
> > Sent: Saturday, July 08, 2017 4:48 PM
> > Subject: Re: [time-nuts] J06 HP-59992A time interval calibrator for
> HP-531xx counters
> >
> >
> >> A run of the mill 2 way power splitter has better than 10ps phase
> matching at 100MHz there are few digital devices that offer that degree of
> matching at best they are usually 10x worse.
> >>
> >> Bruce
> >>
> >>>
> >>>On 09 July 2017 at 06:58 Mark Sims  wrote:
> >>>
> >>>Yes, they do show up... but usually for big-ish bucks. I want to
> build a small affordable replacement that anybody with a 531xx can have.
> >>>
> >>>My design is currently leaning towards a board with the clock
> generator and a 5V reference for the gain calibration (they spec 5V +/-
> 1mV). I was going to use a couple of 2P4T slide switches to route open
> circuit, 5V, normal clock, and inverted clock to the two output connectors.
> >>>
> >>>I think the cost to build would be in the $20 range and fit on a
> 2x2" or so circuit board... certainly more attractive than a $500 big
> ancient box with unobtainium parts in it. The board should be able to
> perform all the calibration steps for the counter.
> >>>
> >>>I don't think the signal requirements are super critical. They are
> using 1:2 splitters and splitter/180 degree phase shifters and relays to
> generate the output signals passively from the inputs. I think a digital
> clock generator would be a LOT more accurate than those phase shifters.
> >>>
> >>>
> >>>
> >
> Actually, you can get J06 HP-59992A calibrators on eBay.
> 
> >
> > ___
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> > and follow the instructions there.
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Bob kb8tq]

Hi

Based on a quick read of the use of the device, they seem to be relying on it 
to be << 100 ps
off from “ideal”.  How much it being non-ideal matters …. not clear. If you are 
correcting for various errors
and eliminating both unknown source errors and destination errors it likely 
gets messy. 

Bob

> On Jul 8, 2017, at 9:14 PM, Tom Van Baak  wrote:
> 
> I knew we had talked about this before:
> https://www.febo.com/pipermail/time-nuts/2006-August/021649.html
> 
> The J06-59992A manual, schematic, app note, and patent are here:
> http://rubidium.dyndns.org/~magnus/instruments/hp/J06-59992A/
> 
> It was designed for the hp 5370 (20 ps) so perhaps the tolerances are less 
> stringent if only used for hp 53132 (150 ps). Maybe one of you RF guys can 
> tell from the schematic?
> 
> Mark writes:
>> Yes, they do show up...  but usually for big-ish bucks.   I want to build a 
>> small affordable replacement that anybody with a 531xx can have. 
> 
> I don't recall them being expensive at all, just unusual. But making a modern 
> one for time nuts is a great idea -- both 5370 and 53131/53132 users. Also, 
> when someone gets around to creating a smart analog front-end to John's TAPR 
> TICC board, your 59992A clone will come in handy.
> 
> Note also this recent document by Bill Riley:
> 
> http://www.stable32.com/A%20High-Resolution%20Time%20Interval%20Counter%20Using%20the%20TAPR%20TADD-2%20and%20TICC%20Modules.pdf
> 
> Hal writes:
>> What does "good" mean?
>> I'd expect the variations due to power or temperature would be easy to  
>> measure.
>> Delay through classic CMOS is linear with absolute temperature and inverse 
>> linear with supply voltage.
> 
> When John created the TAPR TADD-2-mini board I tested the jitter using a 
> TimePod (integrated phase noise mode). I'm looking for the web page or email 
> now, but I recall it was under 2 ps. This is partly due to the fact that the 
> PIC 12F is a fully synchronous MCU; no tricks with double clock edges or 
> PLL's.
> 
> /tvb
> 
> 
> - Original Message - 
> From: "Bruce Griffiths" 
> To: "Mark Sims" ; "Discussion of precise time and 
> frequency measurement" 
> Sent: Saturday, July 08, 2017 4:48 PM
> Subject: Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx 
> counters
> 
> 
>> A run of the mill 2 way power splitter has better than 10ps phase matching 
>> at 100MHz there are few digital devices that offer that degree of matching 
>> at best they are usually 10x worse.
>> 
>> Bruce
>> 
>>> 
>>>On 09 July 2017 at 06:58 Mark Sims  wrote:
>>> 
>>>Yes, they do show up... but usually for big-ish bucks. I want to build a 
>>> small affordable replacement that anybody with a 531xx can have.
>>> 
>>>My design is currently leaning towards a board with the clock generator 
>>> and a 5V reference for the gain calibration (they spec 5V +/- 1mV). I was 
>>> going to use a couple of 2P4T slide switches to route open circuit, 5V, 
>>> normal clock, and inverted clock to the two output connectors.
>>> 
>>>I think the cost to build would be in the $20 range and fit on a 2x2" or 
>>> so circuit board... certainly more attractive than a $500 big ancient box 
>>> with unobtainium parts in it. The board should be able to perform all the 
>>> calibration steps for the counter.
>>> 
>>>I don't think the signal requirements are super critical. They are using 
>>> 1:2 splitters and splitter/180 degree phase shifters and relays to generate 
>>> the output signals passively from the inputs. I think a digital clock 
>>> generator would be a LOT more accurate than those phase shifters.
>>> 
>>>
>>> 
> 
Actually, you can get J06 HP-59992A calibrators on eBay.
 
> 
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Tom Van Baak]

I knew we had talked about this before:
https://www.febo.com/pipermail/time-nuts/2006-August/021649.html

The J06-59992A manual, schematic, app note, and patent are here:
http://rubidium.dyndns.org/~magnus/instruments/hp/J06-59992A/

It was designed for the hp 5370 (20 ps) so perhaps the tolerances are less 
stringent if only used for hp 53132 (150 ps). Maybe one of you RF guys can tell 
from the schematic?

Mark writes:
> Yes, they do show up...  but usually for big-ish bucks.   I want to build a 
> small affordable replacement that anybody with a 531xx can have. 

I don't recall them being expensive at all, just unusual. But making a modern 
one for time nuts is a great idea -- both 5370 and 53131/53132 users. Also, 
when someone gets around to creating a smart analog front-end to John's TAPR 
TICC board, your 59992A clone will come in handy.

Note also this recent document by Bill Riley:

http://www.stable32.com/A%20High-Resolution%20Time%20Interval%20Counter%20Using%20the%20TAPR%20TADD-2%20and%20TICC%20Modules.pdf

Hal writes:
> What does "good" mean?
> I'd expect the variations due to power or temperature would be easy to  
> measure.
> Delay through classic CMOS is linear with absolute temperature and inverse 
> linear with supply voltage.

When John created the TAPR TADD-2-mini board I tested the jitter using a 
TimePod (integrated phase noise mode). I'm looking for the web page or email 
now, but I recall it was under 2 ps. This is partly due to the fact that the 
PIC 12F is a fully synchronous MCU; no tricks with double clock edges or PLL's.

/tvb


- Original Message - 
From: "Bruce Griffiths" 
To: "Mark Sims" ; "Discussion of precise time and frequency 
measurement" 
Sent: Saturday, July 08, 2017 4:48 PM
Subject: Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx 
counters


>A run of the mill 2 way power splitter has better than 10ps phase matching at 
>100MHz there are few digital devices that offer that degree of matching at 
>best they are usually 10x worse.
> 
> Bruce
> 
>> 
>> On 09 July 2017 at 06:58 Mark Sims  wrote:
>> 
>> Yes, they do show up... but usually for big-ish bucks. I want to build a 
>> small affordable replacement that anybody with a 531xx can have.
>> 
>> My design is currently leaning towards a board with the clock generator 
>> and a 5V reference for the gain calibration (they spec 5V +/- 1mV). I was 
>> going to use a couple of 2P4T slide switches to route open circuit, 5V, 
>> normal clock, and inverted clock to the two output connectors.
>> 
>> I think the cost to build would be in the $20 range and fit on a 2x2" or 
>> so circuit board... certainly more attractive than a $500 big ancient box 
>> with unobtainium parts in it. The board should be able to perform all the 
>> calibration steps for the counter.
>> 
>> I don't think the signal requirements are super critical. They are using 
>> 1:2 splitters and splitter/180 degree phase shifters and relays to generate 
>> the output signals passively from the inputs. I think a digital clock 
>> generator would be a LOT more accurate than those phase shifters.
>> 
>> 
>> 
>> > > 
>> > Actually, you can get J06 HP-59992A calibrators on eBay.
>> > 

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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Bruce Griffiths]

The simplest solution to the divider and clock shaper is perhaps to use an 
LTC6954. The LTC6954 offers PECL/CMOS and LVDS outputs together with a low 
jitter (sub ps) programmable (SPI) divider (1-63).A couple of coax relays like 
those from Dow Key microwave together with some hardline and a couple of 
splitters could be used to implement the signal switching. 

> 
> On 09 July 2017 at 09:53 Hal Murray  wrote:
> 
> t...@leapsecond.com said:
> 
> > > 
> > The PIC dividers are good to a couple ps. I suspect the larger 
> > issue is the
> > PCB and wiring design.
> > 
> > > 
> What does "good" mean?
> 
> I'd expect the variations due to power or temperature would be easy to
> measure.
> 
> Delay through classic CMOS is linear with absolute temperature and inverse
> linear with supply voltage.
> 
> The classic way to get time-nuts level noise on FPGA outputs is to wiggle 
> a
> nearby pin. That shouldn't be a problem with a dedicated PIC but would
> probably show up if you are generating multiple frequencies.
> 
> --
> These are my opinions. I hate spam.
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Bruce Griffiths]

A run of the mill 2 way power splitter has better than 10ps phase matching at 
100MHz there are few digital devices that offer that degree of matching at best 
they are usually 10x worse.

Bruce

> 
> On 09 July 2017 at 06:58 Mark Sims  wrote:
> 
> Yes, they do show up... but usually for big-ish bucks. I want to build a 
> small affordable replacement that anybody with a 531xx can have.
> 
> My design is currently leaning towards a board with the clock generator 
> and a 5V reference for the gain calibration (they spec 5V +/- 1mV). I was 
> going to use a couple of 2P4T slide switches to route open circuit, 5V, 
> normal clock, and inverted clock to the two output connectors.
> 
> I think the cost to build would be in the $20 range and fit on a 2x2" or 
> so circuit board... certainly more attractive than a $500 big ancient box 
> with unobtainium parts in it. The board should be able to perform all the 
> calibration steps for the counter.
> 
> I don't think the signal requirements are super critical. They are using 
> 1:2 splitters and splitter/180 degree phase shifters and relays to generate 
> the output signals passively from the inputs. I think a digital clock 
> generator would be a LOT more accurate than those phase shifters.
> 
> 
> 
> > > 
> > Actually, you can get J06 HP-59992A calibrators on eBay.
> > 
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to 
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> > 
> > > 
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Bob kb8tq]

Hi

Good means whatever the 5313x needs for calibration. If that is four signals 
that are 
crossing zero within < 10 ps of the “correct time” then that is the definition 
of good in this case. 

Rise time delay, fall time delay are rarely the same in logic gates. 
Propagation inside a chip to
point A may well be different by nanoseconds relative to the propagation to a 
very similar 
point B. All of that would mess up a signal that *might* need to be 50/50 to 
within 10 ps  or 
a second signal that must cross zero half way in-between (also to within 10 
ps). 

If you want to have a lot of fun with this, pull out the timing analysis tool 
for your favorite
FPGA and start fiddling around.

Bob

> On Jul 8, 2017, at 5:53 PM, Hal Murray  wrote:
> 
> 
> t...@leapsecond.com said:
>> The PIC dividers are good to a couple ps. I suspect the larger issue is the
>> PCB and wiring design. 
> 
> What does "good" mean?
> 
> I'd expect the variations due to power or temperature would be easy to 
> measure.
> 
> Delay through classic CMOS is linear with absolute temperature and inverse 
> linear with supply voltage.
> 
> The classic way to get time-nuts level noise on FPGA outputs is to wiggle a 
> nearby pin.   That shouldn't be a problem with a dedicated PIC but would 
> probably show up if you are generating multiple frequencies.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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[time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Mark Sims]

Yes, they do show up...  but usually for big-ish bucks.   I want to build a 
small affordable replacement that anybody with a 531xx can have.   

My design is currently leaning towards a board with the clock generator and a 
5V reference for the gain calibration (they spec 5V +/- 1mV). I was going 
to use a couple of 2P4T slide switches to route open circuit, 5V,  normal 
clock, and inverted clock to the two output connectors.   

I think the cost to build would be in the $20 range and fit on a 2x2" or so 
circuit board... certainly more attractive than a $500 big ancient box with 
unobtainium parts in it.  The board should be able to perform all the 
calibration steps for the counter.

I don't think the signal requirements are super critical.  They are using 1:2 
splitters and splitter/180 degree phase shifters and relays to generate the 
output signals passively from the inputs.  I think a digital clock generator 
would be a LOT more accurate than those phase shifters.



> Actually, you can get J06 HP-59992A calibrators on eBay.
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Hal Murray]

t...@leapsecond.com said:
> The PIC dividers are good to a couple ps. I suspect the larger issue is the
> PCB and wiring design. 

What does "good" mean?

I'd expect the variations due to power or temperature would be easy to 
measure.

Delay through classic CMOS is linear with absolute temperature and inverse 
linear with supply voltage.

The classic way to get time-nuts level noise on FPGA outputs is to wiggle a 
nearby pin.   That shouldn't be a problem with a dedicated PIC but would 
probably show up if you are generating multiple frequencies.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Papers on timing for lunar laser ranging

[Bert Kehren via time-nuts]

Having used Brooks Shera's GPSDO since 1998 with RB's never OCXO's I still  
am convinced it is the best out there. The problem was the DAC which is not 
 intended for this application. Brooks was working on a LTC1655 replacement 
but  cancer stopped that work.We use the 16 bit LTC1655 with very good 
results. You  ask about resolution and range. With 4 E-14 steps, range is 2.7 
E-9 very  acceptable for any Rb, with 1 E-14 the range is 6.75  E-10. With our 
FRK  test results and my age of 75 I will be glad if I have the opportunity 
to adjust  it once.
We use in our work gate arrays because it is easy to correct mistakes, but  
before getting to know Juerg I did a Brooks 100 MHz board with discrete 
IC's  presently still available from DigiKeys.
 
 
In a message dated 7/8/2017 2:43:01 P.M. Eastern Daylight Time,  
lister...@gmail.com writes:

On Fri, Jul 7,  2017 at 4:14 PM, jimlux  wrote:
> On 7/7/17  3:14 PM, Hal Murray wrote:
>>
>>
>> kb...@n1k.org  said:
>>>
>>> Consider that in 1974, I could buy a  nice new car for less than what a
>>> decent packaged 16 bit DAC  cost.  Go back into the 1960’s and you 
are
>>>  up
>>> into the “several new cars†  range. Even for  NASA projects cost 
did
>>> make it
>>> into the  equation ….
>
>
> Note that these papers are talking about  optical ranging to the 
reflectors
> left on the moon by the Apollo  missions, but the actual work was being 
done
> recently (e.g. it's a  Microsemi 5071 Cesium clock)

Right, this is the "third generation" of  laser ranging. APOLLO started
in 2007, so given
the usual delays in  obtaining grant funding and purchasing, the tech
(pre-upgrade to
the  5071A) is going to be early 2000s tech.

Forgive the ignorance, but why  is there a large disparity between ADC
and DAC capabilities ?
For  example, Linear Technology sell a 24 bit ADC for ~$7 but an 18 bit
DAC is  $30-50...

>
>>
>> When was the first GPSDO shipped  as a commercial product?
>
> An interesting question - at least 20  years ago - XL-DC manual, Rev E, 
from
> 1997
>  http://glacier.lbl.gov/gtp/DOM/Support/xl-dc-manual.pdf
>

I also  found it interesting that the paper says that the GPSDO uses a
2000 sec  Kalman
filter. I've heard of Kalman filters being used for GPS navigation  but
not in timing use, although
I gather things like Thunderbolts use a  ~1000 sec loop constant - is
this the same form of
filtering or have  different forms of filtering become more popular and
Kalman filtering is no  longer
used ?

>
>>
>> There is an interesting  tradeoff in GPSDO design.  With a specific DAC,
>>  you
>> can get finer steps if you reduce the tuning range.  Has  anybody built 
one
>> with a reduced range and a knob on the side to  adjust the center point 
of
>> that range?  You would have to  adjust that knob occasionally as the
>> crystal
>> you are  tuning drifted.
>
>
> My mid 2000s 10 MHz OCXOs from Wenzel  have both EFC and a manual 
adjustment
> of some sort (I'm not sure  what's under the little cap on the side.. a
> trimmer cap or  something?)
>

Right. Apparently the DAC values have changed by  3500 over the ~11
years, which given the
1.2e-11 DAC steps would give an  accumulated change of 4.2e-8, agreeing
with the typical and
quoted  ~1e-11/day drift/aging for a good  OCXO.

Tim
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Charles Steinmetz]

Mark wrote:


 I need a simple and cheap circuit to level shift the TTL signal to +/- 0.50V
 It probably needs clean, stable, fast edges and able to drive a 50 ohm load


See attached.  The resistor values shown assume that the source is a 
0-5v rectangular signal able to source +/- 10mA with negligible voltage 
drop (a single 74AC or 74HC gate will do that).  The edges will be as 
fast as the source.  The symmetry and stability will be the same, as well.


Best regards,

Charles

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[time-nuts] HP 15265A Test Box

[Gary Neilson]

I purchased a HP 8082A pulse generator from Ebay as not working, it 
works fine, pilot lamp is burned out.


Part of the alignment procedure is to use a 15265A Test Box, does anyone 
have a schematic for this unit ?


Thanks

Gary

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Re: [time-nuts] Papers on timing for lunar laser ranging

[Tim Lister]

On Fri, Jul 7, 2017 at 4:14 PM, jimlux  wrote:
> On 7/7/17 3:14 PM, Hal Murray wrote:
>>
>>
>> kb...@n1k.org said:
>>>
>>> Consider that in 1974, I could buy a nice new car for less than what a
>>> decent packaged 16 bit DAC cost.  Go back into the 1960’s and you are
>>> up
>>> into the “several new cars†  range. Even for NASA projects cost did
>>> make it
>>> into the equation ….
>
>
> Note that these papers are talking about optical ranging to the reflectors
> left on the moon by the Apollo missions, but the actual work was being done
> recently (e.g. it's a Microsemi 5071 Cesium clock)

Right, this is the "third generation" of laser ranging. APOLLO started
in 2007, so given
the usual delays in obtaining grant funding and purchasing, the tech
(pre-upgrade to
the 5071A) is going to be early 2000s tech.

Forgive the ignorance, but why is there a large disparity between ADC
and DAC capabilities ?
For example, Linear Technology sell a 24 bit ADC for ~$7 but an 18 bit
DAC is $30-50...

>
>>
>> When was the first GPSDO shipped as a commercial product?
>
> An interesting question - at least 20 years ago - XL-DC manual, Rev E, from
> 1997
> http://glacier.lbl.gov/gtp/DOM/Support/xl-dc-manual.pdf
>

I also found it interesting that the paper says that the GPSDO uses a
2000 sec Kalman
filter. I've heard of Kalman filters being used for GPS navigation but
not in timing use, although
I gather things like Thunderbolts use a ~1000 sec loop constant - is
this the same form of
filtering or have different forms of filtering become more popular and
Kalman filtering is no longer
used ?

>
>>
>> There is an interesting tradeoff in GPSDO design.  With a specific DAC,
>> you
>> can get finer steps if you reduce the tuning range.  Has anybody built one
>> with a reduced range and a knob on the side to adjust the center point of
>> that range?  You would have to adjust that knob occasionally as the
>> crystal
>> you are tuning drifted.
>
>
> My mid 2000s 10 MHz OCXOs from Wenzel have both EFC and a manual adjustment
> of some sort (I'm not sure what's under the little cap on the side.. a
> trimmer cap or something?)
>

Right. Apparently the DAC values have changed by 3500 over the ~11
years, which given the
1.2e-11 DAC steps would give an accumulated change of 4.2e-8, agreeing
with the typical and
quoted ~1e-11/day drift/aging for a good OCXO.

Tim
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Re: [time-nuts] Tuning a Symmetricom 1111C

[Ed Palmer]

Hi Tom,

I have a Datum 4065A standard with a Datum B oscillator.  I've never 
had to tune it, but it appears to be a clone of the HP 10811 so you 
might get some insights by researching that oscillator. However, if 
you're having issues with the +-15V supplies, I'd STRONGLY suggest that 
you resolve those before attempting to retune the oscillator.


Circuit information for these units isn't available, but reading between 
the lines, I note the following:
- My unit uses an AD9713BAP D/A converter to drive the EFC.  It requires 
+-5V supplies.
- The system monitors +5V, +15V, and -15V, but not -5V so where is -5V 
coming from?  I see an LM320-5V on the mainboard near the D/A converter.


My first guess is that -5V is derived from the -15V supply.  If that's 
true, flaky +-15V supplies will almost guarantee a flaky EFC.  Since 
your unit was able to lock once, it further suggests that retuning isn't 
required.


There's a power supply board bolted to one of the side panels that uses 
a couple of DC-DC bricks.  I found some bad solder joints on that 
board.  I can't remember the details.  You might want to check that out.


Since these units are microprocessor controlled and include multiple 
tests and measurements to ensure that the lock is on the correct signal 
peak I don't think it's going to lock to the wrong peak.


You should also be aware that these units use a STEL-1173 chip to drive 
the D/A converter.  This chip is infamous for failing after a few 
years.  If you search the archives you'll find more info on that topic.  
I found a source for this chip a few years ago, but it looks like that 
source has dried up.


Ed

On 2017-07-08 10:00 AM, Tom Knox  wrote:

Hi All;

Does anyone have a data sheet or experience with the Symmetricom C, I have 
one in a Symmetricom 4065C and the internal diagnostics say it is at the end of 
it's tuning range. Is there a way to do a coarse manual adjustment, or is it a 
possibility the Cesium is locking to a side peak? In addition the +- 15 volt 
supplies have failed to switch on twice during testing, but have switch on 
after rebooting. On one reboot it locked quickly.

Thanks;

Thomas Knox



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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Bob kb8tq]

Hi

> On Jul 8, 2017, at 1:31 PM, Tom Van Baak  wrote:
> 
> Mark writes:
> 
>> lots of luck finding one of those
> 
> Actually, you can get J06 HP-59992A calibrators on eBay. You might have to 
> wait a while but I've seen them frequently over time. Note that eBay has an 
> automatic search notification feature so you can get email when one shows up.
> 
> If you want I'll lend you one of my J06 HP-59992A for your calibration. 
> Contact me off-list.
> 
> Bob writes:
> 
>> If a few ns is “ok” it’s an easy task. If the spec is < 10 ps … not quite as 
>> easy. 
> 
> The PIC dividers are good to a couple ps. I suspect the larger issue is the 
> PCB and wiring design.

The jitter on the outputs is indeed good to that level. I’d be surprised if the 
“DC offset” is that good. 
Been wrong before …..

Why do I suspect that data will be forthcoming? :)

Bob


> 
> /tvb
> 
> - Original Message - 
> From: "Mark Sims" 
> To: 
> Sent: Saturday, July 08, 2017 6:31 AM
> Subject: [time-nuts] J06 HP-59992A time interval calibrator for 
> HP-531xxcounters
> 
> 
>> To do a full and proper calibration of the HP-53131/53132/53181 counters you 
>> need a J06 HP-59992A time interval calibrator... lots of luck finding one of 
>> those.   Looking at the manual, it is actually a fairly simple device which 
>> can be greatly simplified for the task of calibrating a 531XX counter.
>> 
>> The main task is to generate 10 MHz square waves with 50% duty cycle.  Four 
>> versions of the signal are generated (two positive and two with inverted 
>> phase).  One of four combos of these signals (P1-P2,  P2-P1,  N1-N2, and 
>> N2-N1) are driven to two output connectors.   The 59992A uses splitters and 
>> phase shifters to generate the signals and can handle analog signals.  The 
>> 531xx cal uses square waves so those signals can be generated digitally.   
>> 
>> My first idea is to take a 20 MHz oscillator and divide it by two to get a 
>> 50% duty cycle. One could also do something like squaring a 10 MHz osc with 
>> something like the Wenzel squarer... that would provide a more stable signal 
>> frequency wise but that might add some asymmetries to the signal.  Feeding 
>> the 10 Mhz osc through a doubler and dividing the squared signal might 
>> provide the best solution.
>> 
>> The 531xx cal procedure uses a +/- 0.50V signal.   I need a simple and cheap 
>> circuit to level shift the TTL signal to +/- 0.50V  It probably needs clean, 
>> stable, fast edges and able to drive a 50 ohm load (the manuals don't 
>> specify the required edge rates and load).   Any ideas for a suitable level 
>> shifter / buffer?  It would also be super nice if it could work from a 
>> single supply...
>> 
>> Also,  if such a cal board was laid out would there be any interest in 
>> making it available for others to build?  
> 
> 
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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters

[Tom Van Baak]

Mark writes:

> lots of luck finding one of those

Actually, you can get J06 HP-59992A calibrators on eBay. You might have to wait 
a while but I've seen them frequently over time. Note that eBay has an 
automatic search notification feature so you can get email when one shows up.

If you want I'll lend you one of my J06 HP-59992A for your calibration. Contact 
me off-list.

Bob writes:

> If a few ns is “ok” it’s an easy task. If the spec is < 10 ps … not quite as 
> easy. 

The PIC dividers are good to a couple ps. I suspect the larger issue is the PCB 
and wiring design.

/tvb

- Original Message - 
From: "Mark Sims" 
To: 
Sent: Saturday, July 08, 2017 6:31 AM
Subject: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xxcounters


> To do a full and proper calibration of the HP-53131/53132/53181 counters you 
> need a J06 HP-59992A time interval calibrator... lots of luck finding one of 
> those.   Looking at the manual, it is actually a fairly simple device which 
> can be greatly simplified for the task of calibrating a 531XX counter.
> 
> The main task is to generate 10 MHz square waves with 50% duty cycle.  Four 
> versions of the signal are generated (two positive and two with inverted 
> phase).  One of four combos of these signals (P1-P2,  P2-P1,  N1-N2, and 
> N2-N1) are driven to two output connectors.   The 59992A uses splitters and 
> phase shifters to generate the signals and can handle analog signals.  The 
> 531xx cal uses square waves so those signals can be generated digitally.   
> 
> My first idea is to take a 20 MHz oscillator and divide it by two to get a 
> 50% duty cycle. One could also do something like squaring a 10 MHz osc with 
> something like the Wenzel squarer... that would provide a more stable signal 
> frequency wise but that might add some asymmetries to the signal.  Feeding 
> the 10 Mhz osc through a doubler and dividing the squared signal might 
> provide the best solution.
> 
> The 531xx cal procedure uses a +/- 0.50V signal.   I need a simple and cheap 
> circuit to level shift the TTL signal to +/- 0.50V  It probably needs clean, 
> stable, fast edges and able to drive a 50 ohm load (the manuals don't specify 
> the required edge rates and load).   Any ideas for a suitable level shifter / 
> buffer?  It would also be super nice if it could work from a single supply...
> 
> Also,  if such a cal board was laid out would there be any interest in making 
> it available for others to build?  


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Re: [time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Bob kb8tq]

Hi

This may be “inside” the envelope for something like a PIC. If not it’s a 
pretty 
easy task for any of the sub $10 FPGA boards. Given the relatively small 
audience, tacking an extra connector or three onto something might be the
better option. 

The big unknown (at least to me) is how close the signals need to be to ideal. 
If a few ns is “ok” it’s an easy task. If the spec is < 10 ps … not quite as 
easy. 
My guess is the 59992A is overkill, but to what degree? 

Bob

> On Jul 8, 2017, at 9:31 AM, Mark Sims  wrote:
> 
> To do a full and proper calibration of the HP-53131/53132/53181 counters you 
> need a J06 HP-59992A time interval calibrator... lots of luck finding one of 
> those.   Looking at the manual, it is actually a fairly simple device which 
> can be greatly simplified for the task of calibrating a 531XX counter.
> 
> The main task is to generate 10 MHz square waves with 50% duty cycle.  Four 
> versions of the signal are generated (two positive and two with inverted 
> phase).  One of four combos of these signals (P1-P2,  P2-P1,  N1-N2, and 
> N2-N1) are driven to two output connectors.   The 59992A uses splitters and 
> phase shifters to generate the signals and can handle analog signals.  The 
> 531xx cal uses square waves so those signals can be generated digitally.   
> 
> My first idea is to take a 20 MHz oscillator and divide it by two to get a 
> 50% duty cycle. One could also do something like squaring a 10 MHz osc with 
> something like the Wenzel squarer... that would provide a more stable signal 
> frequency wise but that might add some asymmetries to the signal.  Feeding 
> the 10 Mhz osc through a doubler and dividing the squared signal might 
> provide the best solution.
> 
> The 531xx cal procedure uses a +/- 0.50V signal.   I need a simple and cheap 
> circuit to level shift the TTL signal to +/- 0.50V  It probably needs clean, 
> stable, fast edges and able to drive a 50 ohm load (the manuals don't specify 
> the required edge rates and load).   Any ideas for a suitable level shifter / 
> buffer?  It would also be super nice if it could work from a single supply...
> 
> Also,  if such a cal board was laid out would there be any interest in making 
> it available for others to build?  
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[time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Mark Sims]

To do a full and proper calibration of the HP-53131/53132/53181 counters you 
need a J06 HP-59992A time interval calibrator... lots of luck finding one of 
those.   Looking at the manual, it is actually a fairly simple device which can 
be greatly simplified for the task of calibrating a 531XX counter.

The main task is to generate 10 MHz square waves with 50% duty cycle.  Four 
versions of the signal are generated (two positive and two with inverted 
phase).  One of four combos of these signals (P1-P2,  P2-P1,  N1-N2, and N2-N1) 
are driven to two output connectors.   The 59992A uses splitters and phase 
shifters to generate the signals and can handle analog signals.  The 531xx cal 
uses square waves so those signals can be generated digitally.   

My first idea is to take a 20 MHz oscillator and divide it by two to get a 50% 
duty cycle. One could also do something like squaring a 10 MHz osc with 
something like the Wenzel squarer... that would provide a more stable signal 
frequency wise but that might add some asymmetries to the signal.  Feeding the 
10 Mhz osc through a doubler and dividing the squared signal might provide the 
best solution.

The 531xx cal procedure uses a +/- 0.50V signal.   I need a simple and cheap 
circuit to level shift the TTL signal to +/- 0.50V  It probably needs clean, 
stable, fast edges and able to drive a 50 ohm load (the manuals don't specify 
the required edge rates and load).   Any ideas for a suitable level shifter / 
buffer?  It would also be super nice if it could work from a single supply...

Also,  if such a cal board was laid out would there be any interest in making 
it available for others to build?  
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