Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[Charles Steinmetz]

Paul wrote:


post down conversion to 10 Khz I was scratching my head as to why not
the TL08X series.


Input voltage noise.  Unless you need the low input current of the 
FET part, there is no need to take the noise hit.  If you *do* need 
the low input current, there are 4 or 5 generations of FET-input 
opamps that are all far superior to the TL0xx parts.  Take a look at 
the OPA134/2134/4134, for example.  (I haven't used TL0xx opamps 
since the '70s.)


BTW:  I suggested using NE5532s instead of LM387s and said they were 
better in every way.  Comparing the LM387 to the NE5532, one might 
notice that the bandwidth spec of the 5532 is lower (10MHz) than that 
of the 387 (15MHz).  But what is important for most applications is 
not the small-signal BW, it is the power BW (full-output BW), which 
depends on the slew rate, not on the SSBW.  The 5532's 9v/uS slew 
rate supports a PBW of 140kHz, while the 387's PBW is only 75kHz (S/R 
is not stated).  (This tells us two things -- first, that the 387's 
slew rate must be <5v/uS; and second, that the 387 has less phase 
margin than the 5532.)


Best regards,

Charles


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[time-nuts] Trimble Thunderbolt E frequency pulling.

[Mark Sims]

My bet is interaction of the load current and power supply with the EFC and/or 
OCXO.  
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[time-nuts] Explanation of how a GPS RX generates time/freq precision?

[Mike Baker]

Hello, Time-Nutters--

I have a couple of friends who have asked how GPS based
time & frequency units arrive at their level of precision.
One sent me some questions and comments (see below)
which indicate his lack of understanding of how GPS
disciplined oscillators can deliver the precision they do.

My question is--  Can anyone on the Time-Nuts list point me
to a source I can give them that will explain how the process
works?  Seems to me that I have seen some papers describing
the process but my search for this info has not turned up
anything suitable that goes into some detail on this.
Any feedback or suggestions on this is much appreciated!!

Mike Baker
Micanopy, FL


Here is what one of the guys sent me:

A 2GHz Intel processor can't measure 10^-12, let alone getting
a P4 to do it.  RS232 delay times are measured in mSec, not
10^-9.  Yes it can time-stamp PPS at 10^-9 if it had a time source
that accurate but that has nothing to do with when the pulse
gets to the receiver or the original time source of the system.

Given that my phone has a 2+ GHz processor / clock and a GPS
receiver, what is the advantage of a 6 GHz (or 10 MHz) oscillator?
I could well believe that system is accurate to 100 nSec (10^-7)
or that a Stratum 0 GPS system good down close to 10^-8
(40 nSec).  I don't see any way of getting down to 10^-12 with
that technology or transmitting a time more accurate than 10^-7.

If the original GPS time source is 10^-7 or a little better, how
can it ever be more accurate than that?

What are we missing?
**

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[time-nuts] PRS10 Heatsink Temperature

[davidh]

Hi All,

I'm moving a PRS10 Rb to a new case. In the current case, the heatsink's 
getting to around 60dC, which is getting close to the maximum operating 
spec of 65dC.


I plan to add a small temperature controlled fan to limit the heatsink 
temperature. Can anyone recommend a suitable setpoint for the heatsink?


Thanks,

david



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Re: [time-nuts] PRS10 1 PPS Out having random phase jumps

[Mark Spencer]

I don't recall ever having this issue with mine.  As a general rule though I 
seemed to have more success using 5 and 10 MHz reference signals vs 1 pps 
reference signals with my HP5370's and HP5335's when making Adev measurements 
of 5 and 10 MHz OCXO's.

Sent from my iPhone

> On Nov 23, 2015, at 12:11 PM, James Robbins  wrote:
> 
> Has anyone using the 1 PPS output from a PRS10 rubidium found significant
> random phase jumps?  I'm getting these random phase jumps while using the
> PRS10 as a TI base for ADEV.  I can use the 10 MHz output of the PRS10 to
> feed a T2mini without any similar jumps.  Wondering if it might be heat
> related or other.  Needless to say, such jumps screw up the TI ADEV readings
> and convert the TimeLab readings from the E-12 range to E-1 or so.  Thanks.
> 
> 
> 
> Jim Robbins
> 
> N1JR
> 
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Re: [time-nuts] PRS10 1 PPS Out having random phase jumps

[Mike Cook]

I’ve not seen this but have only used the 1PPS OUT for validating the perf. 
specs. I have seen no issues over 1-10 secs. Over what time scales are you 
talking  ? Is the 1PPS IN being used to discipline the outputs?



> Le 23 nov. 2015 à 21:11, James Robbins  a écrit :
> 
> Has anyone using the 1 PPS output from a PRS10 rubidium found significant
> random phase jumps?  I'm getting these random phase jumps while using the
> PRS10 as a TI base for ADEV.  I can use the 10 MHz output of the PRS10 to
> feed a T2mini without any similar jumps.  Wondering if it might be heat
> related or other.  Needless to say, such jumps screw up the TI ADEV readings
> and convert the TimeLab readings from the E-12 range to E-1 or so.  Thanks.
> 
> 
> 
> Jim Robbins
> 
> N1JR
> 
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Those who would give up essential Liberty, to purchase a little temporary 
Safety, deserve neither Liberty nor Safety. 
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Re: [time-nuts] PRS10 Heatsink Temperature

[Charles Steinmetz]

David wrote:

I plan to add a small temperature controlled fan to limit the 
heatsink temperature. Can anyone recommend a suitable setpoint for 
the heatsink?


An SRS engineer once told me to keep the PRS10's baseplate 
temperature below 40C.


Best regards,

Charles


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Re: [time-nuts] PRS10 Heatsink Temperature

[davidh]

Charles and Bob,

Thanks. I'll report back on how it works out.

david



n 24/11/2015 10:33 AM, Charles Steinmetz wrote:

David wrote:


I plan to add a small temperature controlled fan to limit the heatsink
temperature. Can anyone recommend a suitable setpoint for the heatsink?


An SRS engineer once told me to keep the PRS10's baseplate temperature
below 40C.

Best regards,

Charles





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[time-nuts] PRS10 1 PPS Out having random phase jumps

[James Robbins]

Jumps can occur over as little as 500 seconds.  There is no pattern which I can 
perceive.  When I look at the TL phase ("P") view, I see strong downward going 
"pulses" in the phase view.  I have tried opening up the enclosure I mounted 
the PRS10 in to cool it.  I can measure the temperature of the case at about 
40dC.  Well below it's spec, I think.  And, no, the 1PPS IN is not being used 
to discipline the outputs.  I can send along a .tim file showing the jumps to 
anyone who is interested and sends me their email.

Jim Robbins
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Re: [time-nuts] PRS10 Heatsink Temperature

[Bob Camp]

Hi

Based on having fried a number of Rb’s …. I’d set it as low as you can without 
it 
going crazy. Something around 35 to 40C is a pretty good target.

Bob

> On Nov 23, 2015, at 2:13 AM, davidh  wrote:
> 
> Hi All,
> 
> I'm moving a PRS10 Rb to a new case. In the current case, the heatsink's 
> getting to around 60dC, which is getting close to the maximum operating spec 
> of 65dC.
> 
> I plan to add a small temperature controlled fan to limit the heatsink 
> temperature. Can anyone recommend a suitable setpoint for the heatsink?
> 
> Thanks,
> 
> david
> 
> 
> 
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Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[paul swed]

Charles great suggestion on the NE5532. Just bread boarded the first
section of the receiver very quickly and the component values work as is.
Thats also as it should be. I need to do a noise check tomorrow but it
appears I can heat up the ole soldering iron and build quite a bit of the
receiver.
Ah the smell of burning insulation and flux in the evening.
Regards
Paul WB8TSL

On Mon, Nov 23, 2015 at 1:28 PM, paul swed  wrote:

> Charles I did see the slew rates and bandwidth and came to the conclusion
> those were not issues. Thats why I will build up a test board pretty
> quickly to confirm the component values still work. They should. It also
> means I do not need to wait for the LM873s to showup. Lots can be wired
> without the LMC6484s.
> Regards
> Paul
> WB8TSL
>
> On Mon, Nov 23, 2015 at 12:16 PM, Charles Steinmetz  > wrote:
>
>> Paul wrote:
>>
>> post down conversion to 10 Khz I was scratching my head as to why not
>>> the TL08X series.
>>>
>>
>> Input voltage noise.  Unless you need the low input current of the FET
>> part, there is no need to take the noise hit.  If you *do* need the low
>> input current, there are 4 or 5 generations of FET-input opamps that are
>> all far superior to the TL0xx parts.  Take a look at the OPA134/2134/4134,
>> for example.  (I haven't used TL0xx opamps since the '70s.)
>>
>> BTW:  I suggested using NE5532s instead of LM387s and said they were
>> better in every way.  Comparing the LM387 to the NE5532, one might notice
>> that the bandwidth spec of the 5532 is lower (10MHz) than that of the 387
>> (15MHz).  But what is important for most applications is not the
>> small-signal BW, it is the power BW (full-output BW), which depends on the
>> slew rate, not on the SSBW.  The 5532's 9v/uS slew rate supports a PBW of
>> 140kHz, while the 387's PBW is only 75kHz (S/R is not stated).  (This tells
>> us two things -- first, that the 387's slew rate must be <5v/uS; and
>> second, that the 387 has less phase margin than the 5532.)
>>
>>
>> Best regards,
>>
>> Charles
>>
>>
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>>
>
>
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Re: [time-nuts] PRS10 1 PPS Out having random phase jumps

[Bob Camp]

Hi

How big are the jumps? Are they all N x some integer ns ?

If so, then yes, I’ve seen Rb’s that do exactly that. The answer is a defective 
divider chip.

Bob

> On Nov 23, 2015, at 6:01 PM, James Robbins  wrote:
> 
> Jumps can occur over as little as 500 seconds.  There is no pattern which I 
> can perceive.  When I look at the TL phase ("P") view, I see strong downward 
> going "pulses" in the phase view.  I have tried opening up the enclosure I 
> mounted the PRS10 in to cool it.  I can measure the temperature of the case 
> at about 40dC.  Well below it's spec, I think.  And, no, the 1PPS IN is not 
> being used to discipline the outputs.  I can send along a .tim file showing 
> the jumps to anyone who is interested and sends me their email.
> 
> Jim Robbins
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Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[Attila Kinali]

On Sun, 22 Nov 2015 21:47:42 -0500
Bob Camp  wrote:

> We have yet to see how well the new modulation format on WWVB helps.

As I have written before, it does not.

See:
https://www.febo.com/pipermail/time-nuts/2013-July/078098.html
https://www.febo.com/pipermail/time-nuts/2013-July/078113.html

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[Charles Steinmetz]

Paul wrote:


It appears that the Chinese sight has the lmc6484 and LM387n at reasonable
prices for small quantities. Most likely will order from there.


No need to buy likely counterfeit parts on ebay.  The LMC6484 is an 
active-status part, available in both DIP and SOIC from all major 
distributors including Mouser, Digi-Key, Arrow, and Avnet (the DIP 
may be EOL, but is still in stock at distributors).  The LM387 is a 
nothing-special, first-generation "low noise" dual opamp.  Its 
dubious claim to fame is that it does not use the industry-standard 
dual opamp pinout.  But since there are no boards available, that 
wouldn't seem to make any difference.  The ubiquitous NE5532, 
available everywhere, is better in every way, with the standard 
pinout.  Or do like the author did and use whatever low-ish noise 
dual opamps you have in *your* junk box.


The PIC16F88 and DS232A are active-status parts, available from 
Microchip and Maxim distributors, respectively.


It seems like a LOT of circuitry to do what really is a pretty simple 
job, though.


Best regards,

Charles


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Re: [time-nuts] Explanation of how a GPS RX generates time/freq precision?

[Attila Kinali]

Moin moin,

On Sun, 22 Nov 2015 21:51:19 -0500
Mike Baker  wrote:

> My question is--  Can anyone on the Time-Nuts list point me
> to a source I can give them that will explain how the process
> works?  Seems to me that I have seen some papers describing
> the process but my search for this info has not turned up
> anything suitable that goes into some detail on this.
> Any feedback or suggestions on this is much appreciated!!

The questions are going into two directions.
One is determining the code phase of the GPS signal
to better than the sampling rate.
And the other one is measuring oscillator phase
and frequency differences.

For the first one I would recommend to have a look at the
book "Understanding GPS: Principles and Applications" by Kaplan et al. 
It contains a very good explanation on how GPS works, with all the
pesky details. Another book worth having a look at is
"Fundamentals of Global Positioning System - A Software Approach",
by Tsui. The latter is more implementation oriented and gives example
code in Matlab.

To give you a intuitive understanding: The GPS code gives you
edges which you measure with your sampling clock. You know where
the "true" edges should be because you know what the code looks
like. Hence you can average over the position of the edges and
get the average. Hence you get a solution which is below the
granularity of your sampling clock. I have not done the calculations
how well this goes, but IIRC you get something of the order of 10ps
RMS error for consumer grade GPS chip.

The next step is measuring the phase offset of your local clock
relative to the GPS generated PPS. For simplicity, i just assume
that the PPS is already sawtooth corrected.
The simple way of doing this is using a counter that is clocked
by the processor. Unfortunately, as you noticed, that gives you
a resolution of at maximum the clock period of your counter
(disregarding metastability effects, again for clarity). But
you can do better if you don't just use a counter. There are
many time to digital converter (TDC) architectures that can
do better. The general idea is that you do not depend on a
counter clock, but make something that is "started" asynchronously
by the PPS and "stopped" by the clock of your local oscillator.
The review paper by Kalisz[1] gives a nice overview of most known
methods TDCs and their advantages/disadvantages.

Usually, for time/phase difference mesurements, involving GPS,
the limit is given by GPS' uncertainty of several ns for
compensated/calibrated systems and several dozens of ns for
uncalibrated systems (due to delays in cables and electronics). 

For frequency measurements, you can do better by measuring
over long intervals, and integrating/averaging. This works
under the assumption that the frequency measurement error
has zero mean, which is (almost) true for all frquency measuremnt
systems build upon phase measurement. With GPS you have to ensure
that GPS does not induce a frequency error and thus often integrate
over integer multiples of 24h (the "repetition" rate of the GPS
satellites). Additionally, any phase offset you have in your system
(due to delays in cables and electronics) falls out in your measurement
of frequency, as you take the difference of two events with the same
phase offset (under the assumption that the delays do not change).

I hope that clears the confusion

Attila Kinali

[1] "Review of methods for time interval measurements with
picosecond resolution", by Josef Kalisz, 2003
http://dx.doi.org/10.1088/0026-1394/41/1/004
http://ztc.wel.wat.edu.pl/met4_1_004.pdf

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Explanation of how a GPS RX generates time/freqprecision?

[Tom Van Baak]

> A 2GHz Intel processor can't measure 10^-12, let alone getting
...
> What are we missing?

Hi Mike,

It sounds like your friend is mixing up time vs. frequency accuracy units. 
Let's just use time units. Here is an easy 1-2-3 GPS accuracy explanation:

1. The clocks in the GPS satellites are good to one nanosecond, which is 10^-9 
second. In fact, if they drift more than half a ns, corrections are applied.

2. Now the bad news. A GPS satellite is far away so the time signal you get at 
home is late due to the speed of light. Note this is the same problem as any 
other radio time system (e.g., TV, WWVB, DCF77, Loran-C). In the case of GPS 
you can assume the satellite is at least 20,000 km away (directly overhead) but 
it might be 25,000 km away (near the horizon). You don't know. So your time 
accuracy is only about 10^-2 second. Note this is worse than WWVB.

3. Now the good news. GPS is a PNT (Position, Navigation, and Timing) system, 
not just a timing system (like WWVB). So the cool thing is that once you 
receive 4 satellites you can calculate where each of the satellites actually is 
and where you are. This allows you to back out the previously unknown light 
travel distance and so your GPS receiver gets time accurate to about 10^-7 
second (100 ns). Note this is much better than WWVB because the distance from 
transmitter to receiver is now precisely known, and also the signal is more 
direct, there are multiple transmitters, the wavelength is much smaller, etc.

Therefore, almost any GPS receiver with a 1PPS output will give you time 
accurate to 100 ns. A system (PC or $1 microcontroller or homebrew TTL circuit) 
can measure or compare time to 100 ns pretty easy; that's only a 10 MHz clock 
speed.

Now about frequency, or average frequency accuracy. If you have a homebrew 
clock that always stays within 100 ns in time, then its average frequency error 
will stay below 100 ns / N s, where N is the duration of your average. For 
example, over 100 seconds your clock frequency accuracy will be 10^-9. And over 
a day it's about 10^-12. Over two weeks it's 10^-13, etc.

Frequency accuracy is measured as the amount of time drift that occurs over a 
long interval. So that's why GPS frequency accuracy numbers appear so small. 
Since there are a million seconds in two weeks a frequency accuracy number may 
look like 10^-13 (0.1 part per trillion) even though the time accuracy number 
is 10^-7 seconds (100 ns).

/tvb


- Original Message - 
From: "Mike Baker" 
To: 
Sent: Sunday, November 22, 2015 6:51 PM
Subject: [time-nuts] Explanation of how a GPS RX generates time/freqprecision?


> Hello, Time-Nutters--
> 
> I have a couple of friends who have asked how GPS based
> time & frequency units arrive at their level of precision.
> One sent me some questions and comments (see below)
> which indicate his lack of understanding of how GPS
> disciplined oscillators can deliver the precision they do.
> 
> My question is--  Can anyone on the Time-Nuts list point me
> to a source I can give them that will explain how the process
> works?  Seems to me that I have seen some papers describing
> the process but my search for this info has not turned up
> anything suitable that goes into some detail on this.
> Any feedback or suggestions on this is much appreciated!!
> 
> Mike Baker
> Micanopy, FL
> 
> 
> Here is what one of the guys sent me:
> 
> A 2GHz Intel processor can't measure 10^-12, let alone getting
> a P4 to do it.  RS232 delay times are measured in mSec, not
> 10^-9.  Yes it can time-stamp PPS at 10^-9 if it had a time source
> that accurate but that has nothing to do with when the pulse
> gets to the receiver or the original time source of the system.
> 
> Given that my phone has a 2+ GHz processor / clock and a GPS
> receiver, what is the advantage of a 6 GHz (or 10 MHz) oscillator?
> I could well believe that system is accurate to 100 nSec (10^-7)
> or that a Stratum 0 GPS system good down close to 10^-8
> (40 nSec).  I don't see any way of getting down to 10^-12 with
> that technology or transmitting a time more accurate than 10^-7.
> 
> If the original GPS time source is 10^-7 or a little better, how
> can it ever be more accurate than that?
> 
> What are we missing?
> **
> 
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Re: [time-nuts] Trimble Thunderbolt E frequency pulling.

[GandalfG8--- via time-nuts]

>   Before I start probing any deeper I'd be interested  to hear if anyone
> else  come across this with the Thunderbolt E.  

Is it thermal?  Can you measure the frequency shift before it has  time to 
warm up?


Switching the impedance at the counter itself resets any plot  that's in 
progress, which does introduce some delay, so I put together a  small switch 
box that could be inserted into the coax and confirmed it's a  rapid effect 
that's unlikely to be thermal.
 
It's even more observable with disciplining turned off  and there's no 
attempt to correct it, I can toggle back and forth  between the two frequencies 
just by switching the load.
 
One thing I did get wrong though when transposing my notes, switching  from 
low to high impedance at the 10Mhz output will increase the frequency,  
with high to low decreasing it again, which is the reverse of what I originally 
 posted...whoops:-)
 
Nigel
GM8PZR




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Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[Alan Melia]

Thanks Bill I had not looked at the date of the latest bulletin just that it 
was still available. I suspect the major use now is the timecode.

Alan
G3NYK

- Original Message - 
From: "Bill Byrom" 

To: 
Sent: Monday, November 23, 2015 12:12 AM
Subject: Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX



The last NPL MSF Bulletin showing their errors was over 4 years ago:
http://resource.npl.co.uk/time/bulletins/bulletin_archive.html
http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-radio-time-signal

The error at a receiver over an interval of a couple of days is nearly
completely due to propagation effects. The variations in propagation
delay far exceed the error in transmitter frequency/phase control unless
there are large changes in the local weather at the transmitter site.

The phase of LF signals at 60 kHz is affected by the effective height of
the ionosphere, which forms a 60 kHz waveguide with the Earth's surface.
Unless you are very close to the transmitter, the amplitude and phase of
the received signal change significantly through each 24 hour period.
WWVB clocks should always measure the signal during the dark path (when
the propagation path between Ft Collins CO and your location is fully
dark), since that is when the signal is strongest and tends to have a
more stable phase.

WWVB clocks can get UTC with an uncertainty of about 100 microseconds,
according to NIST: http://www.nist.gov/pml/div688/grp40/wwvb.cfm

--
Bill Byrom N5BB



On Sun, Nov 22, 2015, at 04:16 PM, Alan Melia wrote:

Hi Bob I have just realised that MSF may work diffently?? The Anthorn
signal is monitored by NPL at Teddington, West of London and frequency
off-sets twice a day are published in parts in 10^12 on their
web-site.involving lot of averaging I think. They do not recommend
using the signal after dark.

You certainly could predict roughly the the skywave phase change during
the
day and the variation as the sun angle changes on the path over the year.
It
gets more difficult if there are flares or geomagnetic storms. If two
independent stations at slightly different distances collect information
it
could be corrected even more accurately.

The same ionospheric problem occurs of course with Loran, and the now
closed
Decca system..

Alan
G3NYK



- Original Message -
From: "Bob Camp" 
To: "Nick Sayer" ; "Discussion of precise time and
frequency
measurement" 
Sent: Sunday, November 22, 2015 7:34 PM
Subject: Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX



Hi

The most basic gotcha with WWVB is that propagation can (and does) shift
the
carrier more than a full cycle over the course of a day. That’s at 60 
KHz,

so one
cycle is a lot (as in 16.666 ppm). Even at one second with a not so 
great

receiver
and a poor antenna, GPS should give you ~0.01 ppm. Right up front, you
have a bit of a problem.
(Yes I’m mixing measurements in that comparison, but the point is still
valid).

What I keep wondering is - There is no big mystery about the WWVB
transmitter's
location. You likely know your own location as well. Part of 
demodulating

the data
gives you day of the year. From that you can figure out some of the 
basics

of the
propagation effects (sunrise is at X:XX sunset is at … etc). You also
could grab stuff
like weather data fairly easily (no idea if that actually helps). If you
fit out the basic
propagation impacts, WWVB could get a lot better. At the very least, you
would know
when to ignore the signal.

So yes, you could do better today than they could back in the good old
days in terms of
the propagation coarse effects.

Unfortunately, there also is data on 24 hour comparisons of WWVB carrier
(same time of
day, one day apart). If you pick your time right (noon or midnight), the
variable propagation
can be reduced quite a bit. Based on that data, you are doing well at 
100

ppt over
24 hours. Might the new modulation help that by 10X? ..maybe. GPS over a
24 hour
period should be giving you something in the 0.1 to 0.01 ppt range (same
sort of pick a likely
stable ionosphere time slot and compare).

Does that make a WWVB device un-interesting? Not by any means. If you
stretch out the
time, both systems get down into the “I have nothing else that good”
range. Checking one
against the other is indeed an interesting thing to do. You just need a
**lot** of time to do it.

Bob



On Nov 22, 2015, at 12:41 PM, Nick Sayer via time-nuts
 wrote:



On Nov 22, 2015, at 7:47 AM, paul swed  wrote:

As mentioned a nice answer to the wwvb modulation change.
I looked up the parts and it seems that they have gone into the NOS
state.
Though you can get some from digikey and such especially in the SOIC
package. Also the VCO isn't available.
It appears that the Chinese sight has the lmc6484 and LM387n at
reasonable
prices for small quantities. Most 

Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[paul swed]

Charles it is a lot of circuitry. But if you want just frequency out then
lots of stuff drops out. Since I have experimented with much of this
already I will do the reduced versions. There is no need for the PIC, the
+- 45 degree chager in the front end, numbers of dividers, output
selectors, analog detection, of the old time code etc.
The one thing I noticed about the LM837n was that its gain bandwidth
products was at least 2-3 X a typical tl084 as an example so a bit better
for 60 KHz.
Really like your suggestion of the NE5532. Have quite few of those will
take a look to see what the implications may be.
Also post down conversion to 10 Khz I was scratching my head as to why not
the TL08X series.
Still a good job and glad it was shared.
Regards
Paul
WB8TSL

On Mon, Nov 23, 2015 at 5:02 AM, Charles Steinmetz 
wrote:

> Paul wrote:
>
> It appears that the Chinese sight has the lmc6484 and LM387n at reasonable
>> prices for small quantities. Most likely will order from there.
>>
>
> No need to buy likely counterfeit parts on ebay.  The LMC6484 is an
> active-status part, available in both DIP and SOIC from all major
> distributors including Mouser, Digi-Key, Arrow, and Avnet (the DIP may be
> EOL, but is still in stock at distributors).  The LM387 is a
> nothing-special, first-generation "low noise" dual opamp.  Its dubious
> claim to fame is that it does not use the industry-standard dual opamp
> pinout.  But since there are no boards available, that wouldn't seem to
> make any difference.  The ubiquitous NE5532, available everywhere, is
> better in every way, with the standard pinout.  Or do like the author did
> and use whatever low-ish noise dual opamps you have in *your* junk box.
>
> The PIC16F88 and DS232A are active-status parts, available from Microchip
> and Maxim distributors, respectively.
>
> It seems like a LOT of circuitry to do what really is a pretty simple job,
> though.
>
> Best regards,
>
> Charles
>
>
>
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Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[Attila Kinali]

On Sun, 22 Nov 2015 13:05:53 -0800
Hal Murray  wrote:

> > I___d have to guess that the PLL would behave better given a 60 kHz 
> > reference
> > rather than a 1 Hz one. But how stable is that 60 kHz reference after going
> > through, what, a thousand miles of ionosphere or so? 
> 
> One of the reasons for using 60 kHz is to avoid the ionosphere.  If you 
> measure the propagation delay, it should be stable.

It is anything but stable, as other people have already written.

I have seen graphs for DCF77 that show "jumps" of 200-300us around
sunrise and sunset. Unfortunately, I cannot find any of them. The
only reliable data I could find is in [1] which shows uncertainties
of a couple of us during the day and close to +/-50us during the night
for a 273km distance.


Attila Kinali

[1] "Time dissemination via the LF transmitter DCF77 using a
pseudo-random phase-shift keying of the carrier", by Hetzel, 1987
http://remco.tk/handig/DCFp.pdf

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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[time-nuts] PRS10 1 PPS Out having random phase jumps

[James Robbins]

Has anyone using the 1 PPS output from a PRS10 rubidium found significant
random phase jumps?  I'm getting these random phase jumps while using the
PRS10 as a TI base for ADEV.  I can use the 10 MHz output of the PRS10 to
feed a T2mini without any similar jumps.  Wondering if it might be heat
related or other.  Needless to say, such jumps screw up the TI ADEV readings
and convert the TimeLab readings from the E-12 range to E-1 or so.  Thanks.

 

Jim Robbins

N1JR

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Re: [time-nuts] KD2BD WWVB receiver/decoder in QEX

[paul swed]

Charles I did see the slew rates and bandwidth and came to the conclusion
those were not issues. Thats why I will build up a test board pretty
quickly to confirm the component values still work. They should. It also
means I do not need to wait for the LM873s to showup. Lots can be wired
without the LMC6484s.
Regards
Paul
WB8TSL

On Mon, Nov 23, 2015 at 12:16 PM, Charles Steinmetz 
wrote:

> Paul wrote:
>
> post down conversion to 10 Khz I was scratching my head as to why not
>> the TL08X series.
>>
>
> Input voltage noise.  Unless you need the low input current of the FET
> part, there is no need to take the noise hit.  If you *do* need the low
> input current, there are 4 or 5 generations of FET-input opamps that are
> all far superior to the TL0xx parts.  Take a look at the OPA134/2134/4134,
> for example.  (I haven't used TL0xx opamps since the '70s.)
>
> BTW:  I suggested using NE5532s instead of LM387s and said they were
> better in every way.  Comparing the LM387 to the NE5532, one might notice
> that the bandwidth spec of the 5532 is lower (10MHz) than that of the 387
> (15MHz).  But what is important for most applications is not the
> small-signal BW, it is the power BW (full-output BW), which depends on the
> slew rate, not on the SSBW.  The 5532's 9v/uS slew rate supports a PBW of
> 140kHz, while the 387's PBW is only 75kHz (S/R is not stated).  (This tells
> us two things -- first, that the 387's slew rate must be <5v/uS; and
> second, that the 387 has less phase margin than the 5532.)
>
>
> Best regards,
>
> Charles
>
>
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