Re: [time-nuts] Mechanical Precision Clocks

[jimlux]

On 3/6/18 5:12 PM, Tom Van Baak wrote:

Hi Adrian,

FYI -- Bill's also a long-time member of time-nuts. And he's also one of the reasons there is 
a time-nuts group. In the mid 90's I met Bill (and also Corby) through classified ads in Nuts 
& Volts magazine. Long story, but it was then that I learned it was "ok" to be 
interested in both vintage mechanical / pendulum clocks and also modern quartz / atomic 
clocks. His pendulum clocks are world-class masterpieces and his home atomic time lab was the 
inspiration for mine.

 From my perspective most historical, horological, mechanical watch & clock 
people are shy (or even dismissive) of anything electronic. Similarly, most 
electronic timekeeping people are ignorant (or even dismissive) of the wonderful 
world of precision mechanical timekeeping. So there's only a small subset of people 
who bridge that gap. Bill is one of them. If you're interested in modern mechanical 
timekeeping, please subscribe to HSN (Horological Science Newsletter) via 
http://www.hsn161.com

If you have any questions for Bill, I'm sure he'd be happy to answer them.




So, where's the ADEV plot for Bill's Q1,Q2, and Q3?

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Re: [time-nuts] Mechanical Precision Clocks

[William H. Fite]

Mr. Scolnik is very well known in mechanical clock circles.

On Tuesday, March 6, 2018, rfnuts  wrote:

> Bill Scolnik's Clocks:
> http://www.precisionclocks.com/index.html
>
> The (non mechanical) standards lab:
> http://www.precisionclocks.com/wpimages/wpe1967732_06.png
>
> Adrian
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-- 
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when it deserves it.
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for sinners. His standards are quite low.
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Re: [time-nuts] Ultra low power RTC

[Bob kb8tq]

Hi

Assuming you are going to run it off a battery. What’s the self discharge
rate on a reasonable battery? 

Bob

> On Mar 6, 2018, at 8:34 PM, Attila Kinali  wrote:
> 
> On Tue, 6 Mar 2018 22:59:34 +
> Mark Sims  wrote:
> 
>> Sparkfun is selling an interesting RTC clock chip board. 
>> It draws 22 nA.  It has a rather novel clock generator...
>> a tuning fork crystal disciplines an RC oscillator every few minutes.
>> They claim 3 minutes per year drift.
> 
> *Sigh* There are a couple of things wrong with that description.
> 
> 1) The part is from Microcrystal, so you can believe the specs
> they publish with high confidence. This also means this is probably
> the exact same chip you will find in Swiss quartz watches.
> (Microcrystal is part of the Swatch group and the main supplier
> of 32kHz oscillators and electronics for the Swiss watch industry)
> 
> 2) The 22nA is the _typical_ consumption in auto-cal mode.
> Max (the number you should design with) is 32nA. Keep in
> mind this number is for the chip alone, no external connection.
> It also includes the implicit condition that all input pins are
> at valid voltage levels. If a pull up/down resistor is too weak
> (because you tried to safe a few more nA) it will result in
> pins being driven by leakage currents, possibly reaching invalid
> voltage levels, which in turn will cause shot-through currents
> through the input stages, increasing the power consumption 10 fold
> at least, 1000 fold easily.
> 
> 3) The current ratings are at 25°C. Going higher means also
> an increase in power consumption. How much, is not specified.
> 
> 4) The 3minutes per year number comes from the +/-3ppm first year
> aging. This is, as usual, at 25°C and is on top of the typ. +/2ppm
> time accuracy. So, the real accuracy is more like 5min after the first
> year... when running from Xtal all the time!
> Which has a typ. 60nA/max 80nA current spec!
> Taking temperature into consideration, assuming something in the order
> of 10 minutes per year is probably more realistic... if you stay
> close to 25°C. The quadratic nature of the temperature dependence
> for tuning fork X-cut crystals causes high deviations pretty quickly
> (In one of the devices I designed, the 10ppm spec of the crystal
> suddenly became 300ppm when taking the whole temperature range at
> which it had to operate into consideration)
> 
> 5) The precision of the auto-cal mode is not specified. It can be
> litterally anything. Especially considering that the datasheet
> talks about using it "several hours at Backup Supply Voltage," 
> i.e. as an emergency measure when the normal power supply is lost.
> 
>   Attila Kinali
> 
> -- 
>   The bad part of Zurich is where the degenerates
>throw DARK chocolate at you.
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Re: [time-nuts] Ultra low power RTC

[Attila Kinali]

On Tue, 6 Mar 2018 22:59:34 +
Mark Sims  wrote:

> Sparkfun is selling an interesting RTC clock chip board. 
> It draws 22 nA.  It has a rather novel clock generator...
> a tuning fork crystal disciplines an RC oscillator every few minutes.
>  They claim 3 minutes per year drift.

*Sigh* There are a couple of things wrong with that description.

1) The part is from Microcrystal, so you can believe the specs
they publish with high confidence. This also means this is probably
the exact same chip you will find in Swiss quartz watches.
(Microcrystal is part of the Swatch group and the main supplier
of 32kHz oscillators and electronics for the Swiss watch industry)

2) The 22nA is the _typical_ consumption in auto-cal mode.
Max (the number you should design with) is 32nA. Keep in
mind this number is for the chip alone, no external connection.
It also includes the implicit condition that all input pins are
at valid voltage levels. If a pull up/down resistor is too weak
(because you tried to safe a few more nA) it will result in
pins being driven by leakage currents, possibly reaching invalid
voltage levels, which in turn will cause shot-through currents
through the input stages, increasing the power consumption 10 fold
at least, 1000 fold easily.

3) The current ratings are at 25°C. Going higher means also
an increase in power consumption. How much, is not specified.

4) The 3minutes per year number comes from the +/-3ppm first year
aging. This is, as usual, at 25°C and is on top of the typ. +/2ppm
time accuracy. So, the real accuracy is more like 5min after the first
year... when running from Xtal all the time!
Which has a typ. 60nA/max 80nA current spec!
Taking temperature into consideration, assuming something in the order
of 10 minutes per year is probably more realistic... if you stay
close to 25°C. The quadratic nature of the temperature dependence
for tuning fork X-cut crystals causes high deviations pretty quickly
(In one of the devices I designed, the 10ppm spec of the crystal
suddenly became 300ppm when taking the whole temperature range at
which it had to operate into consideration)

5) The precision of the auto-cal mode is not specified. It can be
litterally anything. Especially considering that the datasheet
talks about using it "several hours at Backup Supply Voltage," 
i.e. as an emergency measure when the normal power supply is lost.

Attila Kinali

-- 
The bad part of Zurich is where the degenerates
throw DARK chocolate at you.
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Re: [time-nuts] Mechanical Precision Clocks

[Tom Van Baak]

Hi Adrian,

FYI -- Bill's also a long-time member of time-nuts. And he's also one of the 
reasons there is a time-nuts group. In the mid 90's I met Bill (and also Corby) 
through classified ads in Nuts & Volts magazine. Long story, but it was then 
that I learned it was "ok" to be interested in both vintage mechanical / 
pendulum clocks and also modern quartz / atomic clocks. His pendulum clocks are 
world-class masterpieces and his home atomic time lab was the inspiration for 
mine.

>From my perspective most historical, horological, mechanical watch & clock 
>people are shy (or even dismissive) of anything electronic. Similarly, most 
>electronic timekeeping people are ignorant (or even dismissive) of the 
>wonderful world of precision mechanical timekeeping. So there's only a small 
>subset of people who bridge that gap. Bill is one of them. If you're 
>interested in modern mechanical timekeeping, please subscribe to HSN 
>(Horological Science Newsletter) via http://www.hsn161.com

If you have any questions for Bill, I'm sure he'd be happy to answer them.

/tvb


- Original Message - 
From: "rfnuts" 
To: 
Sent: Tuesday, March 06, 2018 4:23 PM
Subject: [time-nuts] Mechanical Precision Clocks


> Bill Scolnik's Clocks:
> http://www.precisionclocks.com/index.html
> 
> The (non mechanical) standards lab:
> http://www.precisionclocks.com/wpimages/wpe1967732_06.png
> 
> Adrian

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Re: [time-nuts] Ultra low power RTC

[Jerry Hancock]

I would have thought better.  

I built a nixie clock from Tubeclocks.com .  Granted it 
is in a pretty constant temperature, but I doubt that clock varies less than 3 
seconds per year.  Peter, the designer, sent me some code that takes a 1PPS but 
I never got it running as I liked the fact that it was undisciplined (like my 
kids) and still incredibly accurate.  I just checked it as it had been running 
4 months since I moved it to my new office and I doubt is off 1/5th a second.

Regards,

Jerry

> On Mar 6, 2018, at 2:59 PM, Mark Sims  wrote:
> 
> Sparkfun is selling an interesting RTC clock chip board.  It draws 22 nA.  It 
> has a rather novel clock generator... a tuning fork crystal disciplines an RC 
> oscillator every few minutes.  They claim 3 minutes per year drift.
> 
> https://www.sparkfun.com/products/14642
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[time-nuts] Mechanical Precision Clocks

[rfnuts]

Bill Scolnik's Clocks:
http://www.precisionclocks.com/index.html

The (non mechanical) standards lab:
http://www.precisionclocks.com/wpimages/wpe1967732_06.png

Adrian
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[time-nuts] Ultra low power RTC

[Mark Sims]

Sparkfun is selling an interesting RTC clock chip board.  It draws 22 nA.  It 
has a rather novel clock generator... a tuning fork crystal disciplines an RC 
oscillator every few minutes.  They claim 3 minutes per year drift.

https://www.sparkfun.com/products/14642
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Re: [time-nuts] ECS ECOC-2522 (was GPS Talking Clock)

[Attila Kinali]

Hoi Nick,

On Mon, 5 Mar 2018 09:36:01 -0800
Nick Sayer via time-nuts  wrote:

> I’ve built two GPSDO units now with this OCXO. For the first one, I fed the 
> DAC (AD5680) from the oscillator’s reference output. This resulted in a very 
> poor (compared to expected) short term ADEV result (1-2 E-11). There was a 
> lot of noise (something like 5 mV P-P) on the reference output. Also, rather 
> oddly, the reference voltage was something like 2.8v. The datasheet doesn’t 
> say what the expected voltage is, but if you were to use that as your DAC 
> reference, you’d be throwing away the top 20% or so of the tuning range.

That sounds weird. Usually the reference voltage is the full scale
of the EFC range. Als, it should be pretty quiet, as it's (again usually)
derived from a internal Zener diode inside the oven. I could understand
a few dozen µV of noise (in a BW of 0.1Hz to 10Hz), but it shouldn't be
more than that. mV level of noise would mean that something is seriously
wrong with the reference.


> For the second unit, I built it with the same circuit I use for the CW 
> OH300, which lacks a reference output. There, instead, I use an NCP51460 
> precision regulator for a reference. There, I achieved a short term ADEV 
> much closer to expectations. It’s just under 6E-12 at tau 1-5s. ECS claims 
> it ought to be closer to 3, but it’s entirely possible that my reference 
> (Thunderbolt) and/or counter (53220A) are contributing error, or that my 
> design has some other noise contribution I haven’t yet found. Still, it’s at 
> least in the ball park. And the oscillator hasn’t even yet been running for 
> 24 hours, so it may get better with some time (I’m a little skeptical about 
> wear-in helping low-tau ADEV though. Doesn’t that usually operate on longer 
> term drift instead?).

For short tau measurements, It is advisable to set the Tbolt into holdover.
If the drift of the Tblot is not negligible, then you can measure its drift
and compensate for it manually after measurement. This will give you more
accurate results for these short tau measurements. 

Also, keep in mind that precision OCXO take a couple of days to settle.
I have a few measurements that a relative high frequency drift up to 
one to three weeks after power up, before the OCXO settles for something
an order of magnitude lower. I don't know the OH300, but they might
exhibit something similar, just at a different timescale. Look at the
datasheet, it should state a number of how many hours/days the OCXO
reaches the stability specs. Another aspect is that you should remove
any apparent phase/frequency drift (and probably other deterministic
effects) before calculating ADEV.



Attila Kinali
-- 
The bad part of Zurich is where the degenerates
throw DARK chocolate at you.
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Re: [time-nuts] Z3801A OCXO manual trimming

[paul swed]

Someone mentioned the right non-lazy approach with a summing/offset opamp.
Do agree. But then just for a try use a V supply and a 10K.
I seem to recall tracing the DAC to an opamp. The EFC line is pretty easily
accessed.
Its one of the little coax cables.
The other even lower risk approach is disconnect the coax and see what
voltage is required to 0 out the 10 MHz.
How far away is it from the DAC feeding the coax connector.
Regards
Paul

On Tue, Mar 6, 2018 at 9:40 AM, Bob kb8tq  wrote:

> Hi
>
> Assuming you can break the EFC lead to the OCXO, you aren’t going to
> damage anything
> inside by feeding the EFC line with +/- 5V. If you are going to tear open
> the OCXO, the line
> will need to be pulled anyway. Without knowing what they drive the EFC
> line with, it’s hard to
> know if the driver on the line would be happy with a back fed voltage.
> Best to be careful ….
>
> Bob
>
> > On Mar 6, 2018, at 3:30 AM, gandalfg8--- via time-nuts <
> time-nuts@febo.com> wrote:
> >
> >
> >
> >
> >
> > Crazy thought.Could you just force a DC offset into the EFC assuming the
> > internal varicap is not out of range.
> > It would be simply adding a resistor to pull up or down to see if you can
> > get a bit of pull and allow the dac to move back in range a bit. Its a
> band
> > aid.
> > I know its sort of crazy. But ripping the oven apart really is no fun at
> > all.
> > Regards
> > Paul
> > WB8TSL
> >
> >
> >
> > **
> >
> > Not really such a crazy thought, I've done this on a Trimble-Nortel
> NTGS50AA where the original 34310-T oscillator had "aged" beyond the 3 to 6
> Volt EFC range.
> >
> > On a unit that was refusing to lock the oscillator was removed and
> confirmed to require an EFC voltage of approx 6.5 Volts for an output
> frequency of 10 MHz. As other tested samples of this oscillator, although
> admittedly not many, required around 4.5 volts there does remain the
> possibility of an actual internal fault but it did test on the bench as
> otherwise ok.
> >
> > Using a simple unity gain level shifter based on a few resistors and a
> TL071 op amp, just because there was one to hand, the EFC voltage from the
> control circuit was shifted 2 Volts high and the unit then behaved as
> expected.
> >
> > The effects of temperature, supply variation, etc on the modified
> circuit were not investigated as this was only a short term test but it
> certainly looked to be a viable proposition, to the extent that rather than
> fit a replaccement 34310-T that board was fitted with SMB connectors using
> the pads provided to keep as a test bed.
> >
> > Nigel GM8PZR
> >
> >
> > ___
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> > and follow the instructions there.
>
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Re: [time-nuts] My Favorite Watch

[Bob kb8tq]

Hi

Most (as in the center of the distribution) afordable  watches are calibrated 
to run fast. 
There is info on this in the archives. A pretty typical target is 10 seconds a 
month.  Yes,
we used that as a target back in the 70’s but it’s still pretty common. You 
have to get 
lucky to find one that is dead on time. 

Some math:

2,592,000 seconds in a month. 1 second is about 0.4 ppm.

Your typical watch crystal moves about 20 PPM over 0 to 50 C. 

The curve is a parabola with a tolerance on the inflection point.

So 10 seconds a month comes out to around 4 ppm. With the temperature out 
around 
20 ppm, you need a fairly stable / consistent environment to hit even that sort 
of number.

Yes, you could play compensation games, but doing so only works to the degree 
that
the crystal matches some ideal curve. ( = you get a pretty limited gain with 
low cost crystals
and no testing). 

Bob

> On Mar 6, 2018, at 3:02 PM, al wolfe  wrote:
> 
> My Timex Indiglo looses about a second a month. I think that's pretty good
> for a <$30 watch I got at Walmart.
> 
> Al
> 
> 
> Virus-free.
> www.avast.com
> 
> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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Re: [time-nuts] My Favorite Watch

[al wolfe]

My Timex Indiglo looses about a second a month. I think that's pretty good
for a <$30 watch I got at Walmart.

Al


Virus-free.
www.avast.com

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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[time-nuts] Z3801A OCXO manual trimming

[Joe Hobart]

Success!

I disassembled the oven and adjusted the OCXO frequency up about 5 Hz.  Lady
Heather reported the DAC changed from +99.99% with no lock to -90% with lock to
GPS.  Hopefully I did not increase the frequency too much.  The long term
aging/drift direction has been down - which caused the loss of lock.  At this
time the DAC has increased slightly to -90.5 as the system settles.

Paul, I also thought about adding an offset voltage to the DAC, but I was
concerned about stability.

Adrian, I thought about an access hole, but when I disassembled the oven, a
piece of the outer heater was partially covering the adjustment access cover and
adjustment.  That required careful moving to access the oscillator adjustment.

Disassembling (ripping is more descriptive) the oven was not difficult.  Putting
everything back together was more tedious.

A huge thanks for all the replies, links to pictures, encouragement, etc.

Joe, W7LUX
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Re: [time-nuts] u-blox F9

[Bob kb8tq]

Hi

Looking at the press release, this is sort of the next step in the process that 
got us
the NovaTel GPS units on eBay as ex-Uber surplus. If they can come up with a 
$1,000
board that replaces the NovaTel $5,000 unit, they have a product …. Will we see 
a 
$100 LEA-9T with the chip in it? Only time will tell. My guess would be not any 
time soon….

Bob

> On Mar 6, 2018, at 5:20 AM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> It seems that u-blox now have an interesting chip coming, according to
> the press-release it has L1/L2/L5 and GPS, GLONASS, GALILEO and BEIDOU
> capability, with RTK support as an option.
> 
> As I have suggested before, the precision would fit the purpose of
> identifying which lane a care is in, something they make explicit
> reference to as a use scenario.
> 
> As for timing support not much is known, but it is interesting.
> 
> https://www.u-blox.com/en/press-releases/u-blox-announces-u-blox-f9-robust-and-versatile-high-precision-positioning-technology
> 
> Cheers,
> Magnus
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Re: [time-nuts] Z3801A OCXO manual trimming

[Bob kb8tq]

Hi

Assuming you can break the EFC lead to the OCXO, you aren’t going to damage 
anything 
inside by feeding the EFC line with +/- 5V. If you are going to tear open the 
OCXO, the line
will need to be pulled anyway. Without knowing what they drive the EFC line 
with, it’s hard to
know if the driver on the line would be happy with a back fed voltage. Best to 
be careful ….

Bob

> On Mar 6, 2018, at 3:30 AM, gandalfg8--- via time-nuts  
> wrote:
> 
> 
> 
> 
> 
> Crazy thought.Could you just force a DC offset into the EFC assuming the
> internal varicap is not out of range.
> It would be simply adding a resistor to pull up or down to see if you can
> get a bit of pull and allow the dac to move back in range a bit. Its a band
> aid.
> I know its sort of crazy. But ripping the oven apart really is no fun at
> all.
> Regards
> Paul
> WB8TSL
> 
> 
> 
> **
> 
> Not really such a crazy thought, I've done this on a Trimble-Nortel NTGS50AA 
> where the original 34310-T oscillator had "aged" beyond the 3 to 6 Volt EFC 
> range.
> 
> On a unit that was refusing to lock the oscillator was removed and confirmed 
> to require an EFC voltage of approx 6.5 Volts for an output frequency of 10 
> MHz. As other tested samples of this oscillator, although admittedly not 
> many, required around 4.5 volts there does remain the possibility of an 
> actual internal fault but it did test on the bench as otherwise ok.
> 
> Using a simple unity gain level shifter based on a few resistors and a TL071 
> op amp, just because there was one to hand, the EFC voltage from the control 
> circuit was shifted 2 Volts high and the unit then behaved as expected.
> 
> The effects of temperature, supply variation, etc on the modified circuit 
> were not investigated as this was only a short term test but it certainly 
> looked to be a viable proposition, to the extent that rather than fit a 
> replaccement 34310-T that board was fitted with SMB connectors using the pads 
> provided to keep as a test bed.
> 
> Nigel GM8PZR
> 
> 
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Re: [time-nuts] Z3801A OCXO manual trimming

[Bob kb8tq]

Hi

The control range should be +/- 5V if I remember correctly. If it’s not, the
only other standard would be 0-5V. There is zero logic in running a wider
swing mod to an OCXO at a lower EFC range. 

It indeed sounds like the DAC has trouble. 

Bob

> On Mar 6, 2018, at 1:24 AM, Mark Sims  wrote:
> 
> I'm not sure what the Z3801A uses for EFC range.   Heather uses the EFC 
> relative command to report the EFC setting.  That command reports values from 
> -100% to 100%.   There is a command that reports the DAC input in counts, but 
> nothing documented that shows volts/count.
> 
> Since the DAC is at -2V with a 99+% DAC setting, it looks like the DAC 
> circuit has issues, or power supply problems.   I think the DAC circuit is a 
> 16 bit DAC with 4 more bits of resolution created by dithering the DAC inputs.
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Re: [time-nuts] TymServe TS2100 dead power supply

[paul swed]

Bob
Classic sign of bad electrolytics.
Several comments.
I have had equipment with small switchers that were separate form the
mother board.
Often an actual supply could be found cheap.
When I can't its time to check the caps. Really cheap to replace.
Regards
Paul
WB8TSL

On Mon, Mar 5, 2018 at 7:52 PM, Bob Martin  wrote:

> We had a brief power outage a few days ago.
>
> My TS2100 didn't power up afterwards. Fuses are fine, AC power delivered
> to power supply, which is producing nothing. Nothing looks/smells fried on
> the power supply.
>
> Couldn't find data on what the power supply output voltages should be; not
> in the meagre documentation, .
>
> I'd appreciate help from someone with a TS2100 while I look for faults in
> this little switching power supply. Looks like three voltages, +5 and what
> else? Is this a more or less standard supply?
>
> Appreciate any help I can get!
>
> Bob K6RTM
>
>
>
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Re: [time-nuts] TymServe TS2100 dead power supply

[Luke Shepherd]

Bob,
Just a reminder, as it came from the factory, this unit has a week rollover
issue unless it has been upgraded.  Check out the TN archives and Google
for the upgrade fix suggestions. (mine was in a production installation
when the rollover occurred, and the resulting pain seems to be forever
etched in my mind.)


Luke.

On Mon, Mar 5, 2018 at 7:52 PM, Bob Martin  wrote:

> We had a brief power outage a few days ago.
>
> My TS2100 didn't power up afterwards. Fuses are fine, AC power delivered
> to power supply, which is producing nothing. Nothing looks/smells fried on
> the power supply.
>
> Couldn't find data on what the power supply output voltages should be; not
> in the meagre documentation, .
>
> I'd appreciate help from someone with a TS2100 while I look for faults in
> this little switching power supply. Looks like three voltages, +5 and what
> else? Is this a more or less standard supply?
>
> Appreciate any help I can get!
>
> Bob K6RTM
>
>
>
> ___
> 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] TymServe TS2100 dead power supply

[Clint Jay]

If it's not restarted after a power down and there's no 'ticking' sound
from it then it's likely to be a problem with the bootstrap supply,
switchers will run for years once they're running but while they're running
the small capacitor (of the order of 47uF) and the resistor that feeds it
(often 220K-470K but can be outside that range) will dry up or go high in
value and as soon as you power it down and try to restart, it fails because
that little circuit doesn't provide the supply needed to kick the chip into
life.

First order of business, check the rails on the secondary for shorts
(tantalums have been mentioned by someone else) and then, after making sure
the main reservoir capacitor is discharged, check and high value resistors
and low voltage/value capacitors on the primary.

The data sheet for SMPSU control chips like the UC3844 usually have a
reference circuit which is often copied by SMPSU manufacturers with only
minor component changes.

On 6 March 2018 at 04:36, Mark Sims  wrote:

> First check for power / ground shorts on the power supply outputs with an
> ohm meter.   There is a good chance of a shorted tantalum cap somewhere in
> the system shutting down the supply.  If the power supply is connected to
> the system via a connector,  disconnect it from the system and see if the
> supply puts out anything.
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-- 
Clint. M0UAW, 2E0EOA, M6KOX

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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[time-nuts] u-blox F9

[Magnus Danielson]

Hi,

It seems that u-blox now have an interesting chip coming, according to
the press-release it has L1/L2/L5 and GPS, GLONASS, GALILEO and BEIDOU
capability, with RTK support as an option.

As I have suggested before, the precision would fit the purpose of
identifying which lane a care is in, something they make explicit
reference to as a use scenario.

As for timing support not much is known, but it is interesting.

https://www.u-blox.com/en/press-releases/u-blox-announces-u-blox-f9-robust-and-versatile-high-precision-positioning-technology

Cheers,
Magnus
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Re: [time-nuts] Need a Watch Recommendation

[Pete Stephenson]

On 3/5/2018 7:38 AM, Don Murray via time-nuts wrote:

> So, Time Nuts...  any suggestions or recommendations?

For non-formal, day-to-day wear, I've been partial to Casio G-Shock
watches for a long time. They're rugged, reliable, and have the basic
features one might want: stopwatch, countdown timer, a few user-settable
alarms, etc. without too many bells and whistles.

Watches with "Multi-Band 6" have long wave time signal receiving
capability and can receive signals from WWVB, MSF, DCF77, and
transmitters in China and Japan.

They also make watches that have GPS receivers, and hybrid GPS and long
wave receivers for redundancy.

I've worn a GWM850-1, which is a Multi-Band 6 watch, for a long time and
it's served me well. Unfortunately, Casio doesn't make that specific
model anymore, but there's lots of other similar models available. Mine
tries to set itself every night starting at midnight and trying again
hourly until it either succeeds at setting the time or it fails after
4:00am. It also charges its internal battery from a solar panel formed
into the watch face, so one never (modulo the battery eventually
degrading) needs to change it. I've found that even with liberal use of
the EL backlight, the battery never gets below the "medium" level during
winter when the watch rarely sees the sun, and then fully charges up
again in springtime.

Cheers!
-Pete

-- 
Pete Stephenson
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Re: [time-nuts] WWV or Net Clock controlled oscillator

[Jim Harman]

Or if you want a bit more of a challenge, you might consider the DS3231
https://datasheets.maximintegrated.com/en/ds/DS3231.pdf

This is a full-featured real time clock with a TCXO. It has a programmable
32KHz or 1 pps output. You can trim the frequency digitally via an I2C port
in increments of about 0.1 ppm.It comes in a small package but you can get
the Chronodot, a breakout version with 0.1" headers from Adafruit and
elsewhere:
https://www.adafruit.com/product/255

You can use the Chronodot by itself or hook it to an Arduino to access the
full range of features.


>
-- 

--Jim Harman
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Re: [time-nuts] Z3801A OCXO manual trimming

[gandalfg8--- via time-nuts]

 


Crazy thought.Could you just force a DC offset into the EFC assuming the
internal varicap is not out of range.
It would be simply adding a resistor to pull up or down to see if you can
get a bit of pull and allow the dac to move back in range a bit. Its a band
aid.
I know its sort of crazy. But ripping the oven apart really is no fun at
all.
Regards
Paul
WB8TSL

 

**

Not really such a crazy thought, I've done this on a Trimble-Nortel NTGS50AA 
where the original 34310-T oscillator had "aged" beyond the 3 to 6 Volt EFC 
range.

On a unit that was refusing to lock the oscillator was removed and confirmed to 
require an EFC voltage of approx 6.5 Volts for an output frequency of 10 MHz. 
As other tested samples of this oscillator, although admittedly not many, 
required around 4.5 volts there does remain the possibility of an actual 
internal fault but it did test on the bench as otherwise ok.

Using a simple unity gain level shifter based on a few resistors and a TL071 op 
amp, just because there was one to hand, the EFC voltage from the control 
circuit was shifted 2 Volts high and the unit then behaved as expected.

The effects of temperature, supply variation, etc on the modified circuit were 
not investigated as this was only a short term test but it certainly looked to 
be a viable proposition, to the extent that rather than fit a replaccement 
34310-T that board was fitted with SMB connectors using the pads provided to 
keep as a test bed.

Nigel GM8PZR


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[time-nuts] My Favorite Accurate Watch

[Alan Woodman]

I recently bought a Citizen Eco-Drive satellite watch that syncs to the 
satellites we all appreciate. I also like not having to worry about batteries 
and the synthetic sapphire crystal keeps it scratch free. It does need to see 
the sky periodically even through windows but re-syncs in a few seconds. I can 
check if it believes it needs to be synced although it does so itself if it can 
see the sky.  It’s multi-functions, while confusing to first set up are 
worthwhile. Only wish it was available in Ti since s/steel is a little heavier 
but it’s the perfect lazy man’s watch for me.
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Re: [time-nuts] Need a Watch Recommendation

[J. L. Trantham]

Don,

I am very pleased with the performance of my CITIZEN Eco-Drive SKYHAWK.  It can 
receive WWVB (USA), JJY (Japan), or DCF77 (Germany).  I am convinced it is 
accurate to within 1 second at all times.  It is a 'Blue Angels' watch, part of 
the NaviHawk series I think.

http://www.citizenwatch-global.com/support/pdf/u600/e.pdf

The link to the manual is above.

Good luck.

Joe

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Don Murray via 
time-nuts
Sent: Monday, March 05, 2018 12:38 AM
To: time-nuts@febo.com
Subject: [time-nuts] Need a Watch Recommendation

Hello Time Nuts...


 
After 6 years of no troubles, in sync with WWV any hour of the day, flawless 
transfer between standard and daylight time my Stauer Titanium Atomic 
wristwatch bite the dust a year ago.
 
Since then, Stauer has sent me three replacements, each with some type of 
problem.  
 
So it looks as if I am in need of a new wristwatch, which will give me some 
kind of time accuracy.
 
So, Time Nuts...  any suggestions or recommendations?
 
TNX
 
73
Don
W4WJ
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