Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 8:09 PM, David G. McGaw wrote:

Actually, an RTL-SDR can because there is direct access to the ADC
available by soldering to internal pads:
www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/  That will give you 8-bit,
14.4Msps.



I'm not sure a 8bit ADC gives enough dynamic range, even after 
downconversion.

The RTL-SDR is a pretty noisy receiver, too.



But as has also been said, a good sound card sampling 24 bits at 192kHz
can be used.

David N1HAC


On 12/4/18 6:54 PM, Poul-Henning Kamp wrote:


In message <2e7cf0ff-4094-2750-4874-96dfe2efe...@earthlink.net>, jimlux writes:


I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.

I don't know about the RTL-SDR, but 8 bits will get you quite far with
slow moving time signals like WWVB because you can average for minutes
if you want - provided you feed the ADC a good stable clock.






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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

Maybe the link came through the list OK?


On 12/4/18 11:16 PM, David G. McGaw wrote:
> Sorry about that garbled link.  Blame Dartmouth's over-zealous IT. Just
> look for "rtl-sdr direct sampling mode" at rtl-sdr dot com.
>
>
> On 12/4/18 11:09 PM, David G. McGaw wrote:
>> Actually, an RTL-SDR can because there is direct access to the ADC
>> available by soldering to internal pads:
>> https://na01.safelinks.protection.outlook.com/?url=www.rtl-sdr.com%2Frtl-sdr-direct-sampling-mode%2Fdata=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C60246767b871406285c808d65a68a8a7%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636795802882698879sdata=qu9IZ7jrigjcDqD%2B1d9daSfIHttr3Nn%2Fh0L5mg%2FTsbg%3Dreserved=0
>>   That will give you 8-bit,
>> 14.4Msps.
>>
>> But as has also been said, a good sound card sampling 24 bits at 192kHz
>> can be used.
>>
>> David N1HAC
>>
>>
>> On 12/4/18 6:54 PM, Poul-Henning Kamp wrote:
>>> 
>>> In message <2e7cf0ff-4094-2750-4874-96dfe2efe...@earthlink.net>, jimlux 
>>> writes:
>>>
 I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
>>> I don't know about the RTL-SDR, but 8 bits will get you quite far with
>>> slow moving time signals like WWVB because you can average for minutes
>>> if you want - provided you feed the ADC a good stable clock.
>>>
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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

Sorry about that garbled link.  Blame Dartmouth's over-zealous IT. Just 
look for "rtl-sdr direct sampling mode" at rtl-sdr dot com.


On 12/4/18 11:09 PM, David G. McGaw wrote:
> Actually, an RTL-SDR can because there is direct access to the ADC
> available by soldering to internal pads:
> https://na01.safelinks.protection.outlook.com/?url=www.rtl-sdr.com%2Frtl-sdr-direct-sampling-mode%2Fdata=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C26d18a151e124b336e5008d65a679402%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636795798255645762sdata=k7qbMd66xKxoL28CemtFlw5cbhLHMgU01NZlOnfY7Lw%3Dreserved=0
>   That will give you 8-bit,
> 14.4Msps.
>
> But as has also been said, a good sound card sampling 24 bits at 192kHz
> can be used.
>
> David N1HAC
>
>
> On 12/4/18 6:54 PM, Poul-Henning Kamp wrote:
>> 
>> In message <2e7cf0ff-4094-2750-4874-96dfe2efe...@earthlink.net>, jimlux 
>> writes:
>>
>>> I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
>> I don't know about the RTL-SDR, but 8 bits will get you quite far with
>> slow moving time signals like WWVB because you can average for minutes
>> if you want - provided you feed the ADC a good stable clock.
>>
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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

Any of the RSPs from SDRPlay will cover it and they are great units, 
starting at $109 US.  I am literally using an RSP1A right now.

David N1AHC


On 12/4/18 9:08 PM, W7SLS wrote:
> Hello,
>
> Great discussion on this and other topics here.
>
> Just looked up the specs for the SDRPlay RSP2:
>   1 kHz to 2 GHz.
> Should be fine for 60 kHz.
>
> Now to look closer at previous posts for 60 kHz antennas, how to get raw data 
> out of the RSP2 (other than pretty pictures), and see where it fits on the 
> project list.
>
> Regards,
> Scott W7SLS
>
>
>> On Dec 4, 2018, at 4:04 PM, Iain Young  wrote:
>>
>>
>>
>> On 04/12/18 23:08, jimlux wrote:
>>> On 12/4/18 2:52 PM, Poul-Henning Kamp wrote:
 
 In message <20181204224816.bfef2926d942b52db8061...@kinali.ch>, Attila 
 Kinali writes:

> On Tue, 4 Dec 2018 13:12:48 -0800
> jimlux  wrote:
>
>> I maintain that it's the lack of a cheap RF front end that is the sticky 
>> point.
 Then you have misunderstood how little you actually need.
>>> I should clarify - "cheap *off-the-shelf* catalog RF front end"
>>> In my old codger-ness with limited free time, I'm just not wild about 
>>> wiring up circuits from scratch.  And, I like to see other people duplicate 
>>> what I've done, so I've tended to move towards "I can buy that widget for 
>>> $20-100" kinds of things.
>>> Hence my 4 channel RTL-SDR+beagle phased array.
>>> I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
>> Probably not - Even the Funcube dongle down that low doesn't pick up
>> MSF from here in the UK, and at 66kHz I get BBC Radio 4 (198/3=66..)
>>
>> However, my main SDR PC has a 192kHz soundcard. Feed that with my
>> LF active antenna, and MSF, DCF, amongst others come booming in.
>>
>> Don't discount an active antenna plus a soundcard or ADC that will
>> sample 192kHz
>>
>>
>> Iain
>>
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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

Actually, an RTL-SDR can because there is direct access to the ADC 
available by soldering to internal pads: 
www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/  That will give you 8-bit, 
14.4Msps.

But as has also been said, a good sound card sampling 24 bits at 192kHz 
can be used.

David N1HAC


On 12/4/18 6:54 PM, Poul-Henning Kamp wrote:
> 
> In message <2e7cf0ff-4094-2750-4874-96dfe2efe...@earthlink.net>, jimlux 
> writes:
>
>> I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.
> I don't know about the RTL-SDR, but 8 bits will get you quite far with
> slow moving time signals like WWVB because you can average for minutes
> if you want - provided you feed the ADC a good stable clock.
>

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Re: [time-nuts] new WWVB BPSK dev board

[W7SLS]

Hello,

Great discussion on this and other topics here.

Just looked up the specs for the SDRPlay RSP2:
1 kHz to 2 GHz.
Should be fine for 60 kHz.

Now to look closer at previous posts for 60 kHz antennas, how to get raw data 
out of the RSP2 (other than pretty pictures), and see where it fits on the 
project list.

Regards,
Scott W7SLS


> On Dec 4, 2018, at 4:04 PM, Iain Young  wrote:
> 
> 
> 
> On 04/12/18 23:08, jimlux wrote:
>> On 12/4/18 2:52 PM, Poul-Henning Kamp wrote:
>>> 
>>> In message <20181204224816.bfef2926d942b52db8061...@kinali.ch>, Attila 
>>> Kinali writes:
>>> 
 On Tue, 4 Dec 2018 13:12:48 -0800
 jimlux  wrote:
 
> I maintain that it's the lack of a cheap RF front end that is the sticky 
> point.
>>> 
>>> Then you have misunderstood how little you actually need.
>> I should clarify - "cheap *off-the-shelf* catalog RF front end"
>> In my old codger-ness with limited free time, I'm just not wild about wiring 
>> up circuits from scratch.  And, I like to see other people duplicate what 
>> I've done, so I've tended to move towards "I can buy that widget for 
>> $20-100" kinds of things.
>> Hence my 4 channel RTL-SDR+beagle phased array.
>> I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz. 
> 
> Probably not - Even the Funcube dongle down that low doesn't pick up
> MSF from here in the UK, and at 66kHz I get BBC Radio 4 (198/3=66..)
> 
> However, my main SDR PC has a 192kHz soundcard. Feed that with my
> LF active antenna, and MSF, DCF, amongst others come booming in.
> 
> Don't discount an active antenna plus a soundcard or ADC that will
> sample 192kHz
> 
> 
> Iain
> 
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Re: [time-nuts] new WWVB BPSK dev board

[Gilles Clement]

Hi,
In France the carrier frequency is 162khz (Allouis)
Phase modulated over one minute.
Gilles.

Envoyé de mon iPad

> Le 5 déc. 2018 à 00:57, Paul Bicknell  a écrit :
> 
> Hi Nigel 
> 
> I moved from Warwickshire to west Sussex  south of the downs 20 years ago
> and all was OK But since it moved I have not bean able to use the 60 Khz
> reference  I am thinking of setting up a reference to use the one in France
> I think it is 192 Khz 
> And then I can do a frequency difference between the 2 
> Also Looking for a rabid 
> 
> Best regards Paul 
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of
> gandalfg8--- via time-nuts
> Sent: 04 December 2018 12:12
> To: time-nuts@lists.febo.com
> Cc: gandal...@aol.com
> Subject: [time-nuts] new WWVB BPSK dev board
> 
> Hi Paul,
> 
> It was shifted over 11 years ago, very obligingly timed to follow my move
> from the South East to Scotland:-),
> 
> so I suspect any resulting propogational changes would have been well
> documented by now.
> 
> Nigel GM8PZR
> 
> Hi thank you Bob for the mail 
> 
> Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
> centre of England north by more than 200 miles 
> Paul 
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Re: [time-nuts] Detecting gravity with optical atomic clocks

[Neville Michie]

What I found interesting was that a pendulum, with a reasonably high Q, could 
acquire energy
from the seismic disturbance to shift its phase.
Now a 10Kg pendulum would require a significant amount of energy, and it can 
only
absorb energy of a very narrow bandwidth, which is calculable from its Q.
The energy can be calculated, I think, from the phase shift and the amplitude 
of the swing.
The total amount of energy over the whole spectrum must have been quite high.
Cheers, Neville Michie


> On 2 Dec 2018, at 12:45, Tom Van Baak  wrote:
> 
> "Paul Bicknell" --
>> Any chance of a picture of your Synchronome pendulum clock and associated
>> timing / logging equipment 
> 
> Yes, I'll update that page with more info and photos at some point.
> Meanwhile there are some links to follow at the end of the page:
> http://leapsecond.com/pend/synchronome/quake.htm
> 
> 
> 
> "Didier Juges" --
>> Tom,
>> I suspect something so sensitive gives you significant "false positives"
>> when a delivery truck goes by. I assume you try to correlate your data with
>> other enthusiasts nearby to resolve those discrepancies the way we do with
>> our clocks?
> 
> The pendulum is directly bolted to large thick basement corner wall. Local 
> door slams or delivery trucks have no effect that I've ever seen. But a 7.0 
> earthquake is truly massive and it creates ground motion at the many microns 
> to mm levels even 1500 miles away. A precision pendulum clock is affected by 
> this level of vibration, especially when it persists for many minutes.
> 
> Yes, the pendulum data correlates in time with professional seismometer 
> stations here and around the northwest.
> 
> 
> 
> "Hal Murray", "Poul-Henning Kamp" --
>> And can you reverse-engineer the local ground movement from the
>> pendulum measurements ?
> 
> For quartz, rubidium, and pendulum clocks, it is possible to partially 
> reverse-engineer effects of temperature, pressure, and humidity. These are 
> scaler quantities and very slow moving processes.
> 
> Seismic effects on pendulums are a whole different problem. It's a 3D vector 
> quantity. They are very dynamic (rapidly changing), with a complex power 
> spectrum. And the interaction of ground acceleration with a swinging pendulum 
> is extremely dependent on angles and on the instantaneous pendulum phase vs. 
> seismic power relationship, which is changing every millisecond and lasts for 
> minutes. Plus the pendulum reaction to some of these changes is non-linear. 
> As Bob would say, lot's of fun.
> 
> In theory if you had several pendulums arranged around a circle, and used 
> ultra wide band seismometers (or super high resolution accelerometers), and 
> took measurements at 10 to 100 Hz, then I suspect computer simulations might 
> be able to make some predictions out of the data. Which you could then back 
> out.
> 
> /tvb
> 
> 
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Re: [time-nuts] new WWVB BPSK dev board

[Paul Bicknell]

Hi Nigel 

I moved from Warwickshire to west Sussex  south of the downs 20 years ago
and all was OK But since it moved I have not bean able to use the 60 Khz
reference  I am thinking of setting up a reference to use the one in France
I think it is 192 Khz 
And then I can do a frequency difference between the 2 
Also Looking for a rabid 

Best regards Paul 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of
gandalfg8--- via time-nuts
Sent: 04 December 2018 12:12
To: time-nuts@lists.febo.com
Cc: gandal...@aol.com
Subject: [time-nuts] new WWVB BPSK dev board

Hi Paul,

It was shifted over 11 years ago, very obligingly timed to follow my move
from the South East to Scotland:-),

so I suspect any resulting propogational changes would have been well
documented by now.

Nigel GM8PZR

Hi thank you Bob for the mail 

Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
centre of England north by more than 200 miles 
Paul 
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Re: [time-nuts] new WWVB BPSK dev board

[Iain Young]

On 04/12/18 23:08, jimlux wrote:

On 12/4/18 2:52 PM, Poul-Henning Kamp wrote:


In message <20181204224816.bfef2926d942b52db8061...@kinali.ch>, Attila 
Kinali writes:



On Tue, 4 Dec 2018 13:12:48 -0800
jimlux  wrote:

I maintain that it's the lack of a cheap RF front end that is the 
sticky point.


Then you have misunderstood how little you actually need.


I should clarify - "cheap *off-the-shelf* catalog RF front end"

In my old codger-ness with limited free time, I'm just not wild about 
wiring up circuits from scratch.  And, I like to see other people 
duplicate what I've done, so I've tended to move towards "I can buy that 
widget for $20-100" kinds of things.


Hence my 4 channel RTL-SDR+beagle phased array.

I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz. 


Probably not - Even the Funcube dongle down that low doesn't pick up
MSF from here in the UK, and at 66kHz I get BBC Radio 4 (198/3=66..)

However, my main SDR PC has a 192kHz soundcard. Feed that with my
LF active antenna, and MSF, DCF, amongst others come booming in.

Don't discount an active antenna plus a soundcard or ADC that will
sample 192kHz


Iain

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Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 2:52 PM, Poul-Henning Kamp wrote:


In message <20181204224816.bfef2926d942b52db8061...@kinali.ch>, Attila Kinali 
writes:


On Tue, 4 Dec 2018 13:12:48 -0800
jimlux  wrote:


I maintain that it's the lack of a cheap RF front end that is the sticky point.


Then you have misunderstood how little you actually need.


I should clarify - "cheap *off-the-shelf* catalog RF front end"

In my old codger-ness with limited free time, I'm just not wild about 
wiring up circuits from scratch.  And, I like to see other people 
duplicate what I've done, so I've tended to move towards "I can buy that 
widget for $20-100" kinds of things.


Hence my 4 channel RTL-SDR+beagle phased array.

I'm going to bet that the 8 bit RTL-SDR isn't going to work on 60kHz.


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Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 2:28 PM, John Moran, Scawby Design wrote:

I'm a little puzzled as to why people keep calling 60kHz - 'RF'. Many Hi-Fi 
audio amplifiers go higher than that.

As for an 'RF' front end, there are dozens of off-the-shelf op-amps that can 
amplify the signal from a tuned ferrite rod aerial sufficiently to then feed 
into a decent A-D and then a micro.


yes, and someone has to pick one of them and put it on a board, with a 
voltage regulator and other parts.


It's not complex, but it's also not something you can buy off the shelf, 
plug into your RPi and start coding up the filter.





Analog Devices have A-Ds that digitize the carrier of 12GHz RF signals so I 
think we should be able to manage 60kHz ... the problem then being to process 
the resulting data stream.


I don't think the ADC is the challenge - a decent tuned front end with 
some gain so that the signal is around a volt, and you can feed the 
onchip ADC of most microcontrollers and you'll be all set.


If you had a wide open front end, with AM broadcast, all manner of RFI, 
and so forth, you'd probably need more bits.  But a few kHz sample rate 
would probably work, if your sample and hold was good - if it isn't then 
maybe a couple hundred kHz sample rate.


Easy to do with most microcontrollers on an off the shelf board.





However, fast A-Ds are not particularly cheap and you would need circa 50MHz 
sample rate to resolve 1deg of the carrier, and TVB has already stated that 
there are no time benefits to BPSK, so this is all just an interesting 
technical exercise, isn't it?


Your sample rate doesn't have to be anywhere near the resolution - what 
you do is fit a sine wave to the samples you have and you can easily get 
sub-sample accuracy.  The important thing is the SNR.   Higher sample 
rates do help, because they basically give you that Sqrt(N) improvement 
in SNR over a single sample.



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Re: [time-nuts] new WWVB BPSK dev board

[Poul-Henning Kamp]

In message 
,
 "John Moran, Scawby Design"
 writes:

>However, fast A-Ds are not particularly cheap and you would need
>circa 50MHz sample rate to resolve 1deg of the carrier, and TVB has
>already stated that there are no time benefits to BPSK, so this is
>all just an interesting technical exercise, isn't it?

I admit it would be interesting to do the allan variance on it,
but measuring the carrier to 1 degree in every single cycle is
way overkill.

1 MHz sampling rate is fine, but go for 5 or 10 MHz so you can
drive the ADC directly from your house-standard.

And BPSK *does* improve the timing, because you can very precisely
measure when the change of phase happens, and it since it happens
at a carrier zero-crossing you can filter it down to +/- sample.

-- 
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Re: [time-nuts] new WWVB BPSK dev board

[Poul-Henning Kamp]

In message <20181204222100.293dc3259cf1d8683daec...@kinali.ch>, Attila Kinali 
writes:

>BPSK by itself does not improve timing. At most it improves reception
>by having a constant power envelope. But in case of WWVB, where
>the AM modulation is still kept, this is not the case. The phase
>changes do not help reception at all. In order to help reception,
>one needs to send a _known_ bit string in order for a corrolator
>in the receiver to pick the signal out of the noise. 

They do that in the "long" sequence, read their spec.

The fact that it is one out of 100-some known sequences does not
significantly change that situation.

And the BPSK does improve timing.

If you have access to, and tracks the carrier, you can nail the
timing all the way down to 1/your_sample_rate.

Been there, done that with DCF77 no big deal.

Even the weird phase-modulation of RDF and BBC on 198kHz can be
nailed down very precisely that way.

But the crucial thing is:  You need to digitize the carrier.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] new WWVB BPSK dev board

[Poul-Henning Kamp]

In message <20181204224816.bfef2926d942b52db8061...@kinali.ch>, Attila Kinali 
writes:

>On Tue, 4 Dec 2018 13:12:48 -0800
>jimlux  wrote:
>
>> I maintain that it's the lack of a cheap RF front end that is the sticky 
>> point.

Then you have misunderstood how little you actually need.

This is the "front-end" I ran most of my VLF experiments with:

http://phk.freebsd.dk/loran-c/Antenna/

A single AD797 and via 10m of coax directly into an ADC.

Modern capacitor-based ADCs work fine with even very small signals,
many can be run with sub-volt VREF and still be perfectly happy.

There really isn't anything to it...

The only reason I'm not active in VLF any more is that I have to
choose between VLF reception or my robotic lawn-mowers, and with
5000m² of lawn, that is not even a close call.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
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Re: [time-nuts] new WWVB BPSK dev board

[John Moran, Scawby Design]

I'm a little puzzled as to why people keep calling 60kHz - 'RF'. Many Hi-Fi 
audio amplifiers go higher than that.

As for an 'RF' front end, there are dozens of off-the-shelf op-amps that can 
amplify the signal from a tuned ferrite rod aerial sufficiently to then feed 
into a decent A-D and then a micro.

Analog Devices have A-Ds that digitize the carrier of 12GHz RF signals so I 
think we should be able to manage 60kHz ... the problem then being to process 
the resulting data stream.

However, fast A-Ds are not particularly cheap and you would need circa 50MHz 
sample rate to resolve 1deg of the carrier, and TVB has already stated that 
there are no time benefits to BPSK, so this is all just an interesting 
technical exercise, isn't it?

John Moran
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Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 1:48 PM, Attila Kinali wrote:

On Tue, 4 Dec 2018 13:12:48 -0800
jimlux  wrote:


I maintain that it's the lack of a cheap RF front end that is the sticky
point.


Doing a 2-3 stage transistor based amplifier should give the signal
enough gain to be sampled with the ADC of a uC. I have such a design
sitting around, that I did a couple of years back for DCF77, but never
got around to actually built it (see attachment).

It is meant to be run from 4V, so that one can use an unstable/noisy
5V source with an 4V LDO and should give ~70dB of total gain. I used
BC547 in the simulation, but any NPN with decent h_fe and f_t should
do (eg 2N, 2N3904,...). The 2N5484 is a bit harder to replace,
as I selected it for its low V_th and narrow specified V_th range.

All that is needed for this to work is a tuned antenna, ie a ferrite
rod with a capcitor on it that is approximately tuned to 60/77.5kHz.

Attila Kinali




17 passive components and 4 active components. plus the loopstick and 
tuning cap. I think you'd need pretty substantial volumes to get the 
"assembled and delivered" price below $20.


I usually use the rule of thumb that the BOM cost has to be 1/5th to 
1/10th the retail price.  So $2.
You might get there.. the MMBF5484 is 12 cents in qty 100. I assume you 
can find a NPN for less than 10 cents - The LDO might be the most 
expensive part.






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Re: [time-nuts] new WWVB BPSK dev board

[Bob kb8tq]

Hi

Given the large “fade” of WWVB over a 24 hour period (it’s not always ground 
wave ….) most decent receivers in the past have run a front end with AGC on it. 
Indeed 24 bit ADC’s ( > 16 bit ENOB)  are out there for not a massive amount of 
money.  

It is a bit unclear just how much fade you need to compensate for until you get 
past the “that’s enough” point. There are a number of nasty points in the 
country 
you would need to check out. Since you also are trying to deal with an enormous 
amount of “crud” at the same time, there may not be an exact answer. 

Bob

> On Dec 4, 2018, at 4:48 PM, Attila Kinali  wrote:
> 
> On Tue, 4 Dec 2018 13:12:48 -0800
> jimlux  wrote:
> 
>> I maintain that it's the lack of a cheap RF front end that is the sticky 
>> point.
> 
> Doing a 2-3 stage transistor based amplifier should give the signal
> enough gain to be sampled with the ADC of a uC. I have such a design
> sitting around, that I did a couple of years back for DCF77, but never
> got around to actually built it (see attachment). 
> 
> It is meant to be run from 4V, so that one can use an unstable/noisy
> 5V source with an 4V LDO and should give ~70dB of total gain. I used
> BC547 in the simulation, but any NPN with decent h_fe and f_t should
> do (eg 2N, 2N3904,...). The 2N5484 is a bit harder to replace,
> as I selected it for its low V_th and narrow specified V_th range.
> 
> All that is needed for this to work is a tuned antenna, ie a ferrite
> rod with a capcitor on it that is approximately tuned to 60/77.5kHz.
> 
>   Attila Kinali
> 
> -- 
>   The bad part of Zurich is where the degenerates
>throw DARK chocolate at you.
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Re: [time-nuts] Ashtech Z12T

[Magnus Danielson]

Hi Bob,

On 12/3/18 2:42 PM, Bob kb8tq wrote:
> Hi
> 
> Ok, if frequency is the only concern, then a fairly conventional GPSDO would 
> do the job.
> One of many out there is the FS 740. 
> 
> https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdfAnother 
> 
> There are a lot of others. The approach used is normally a very long 
> comparison ( as in 
> weeks). The advantage is that they are pretty much “plug and play” with 
> little intervention
> required from the user. 
> 
> The Novatel boards 
> 
> https://www.novatel.com/assets/Documents/Papers/OEM7-Receivers-BR-D21517-v1.pdf
>  
> 
> 
> are a more “hands on” way to do the task. There would be some software 
> development 
> required on your part to get them going. They would allow more careful 
> control over the 
> exact nature of the comparison. 
> 
> Indeed there are a number of similar devices on the surplus market. The two 
> items above 
> are only a random selection of what’s out there. 
> 
> In the US, NIST used to supply a service (for a charge of course) that set up 
> a comparison 
> system at your location. I do not know if there are similar services 
> available outside the US. 

I've been shown one in a certain German vendors location as they just
recently got it. They where proud and happy. I really enjoyed seeing it
there, that they took the step.

Cheers,
Magnus

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Re: [time-nuts] new WWVB BPSK dev board

[Attila Kinali]

On Tue, 4 Dec 2018 13:12:48 -0800
jimlux  wrote:

> I maintain that it's the lack of a cheap RF front end that is the sticky 
> point.

Doing a 2-3 stage transistor based amplifier should give the signal
enough gain to be sampled with the ADC of a uC. I have such a design
sitting around, that I did a couple of years back for DCF77, but never
got around to actually built it (see attachment). 

It is meant to be run from 4V, so that one can use an unstable/noisy
5V source with an 4V LDO and should give ~70dB of total gain. I used
BC547 in the simulation, but any NPN with decent h_fe and f_t should
do (eg 2N, 2N3904,...). The 2N5484 is a bit harder to replace,
as I selected it for its low V_th and narrow specified V_th range.

All that is needed for this to work is a tuned antenna, ie a ferrite
rod with a capcitor on it that is approximately tuned to 60/77.5kHz.

Attila Kinali

-- 
The bad part of Zurich is where the degenerates
throw DARK chocolate at you.
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Re: [time-nuts] new WWVB BPSK dev board

[Bob kb8tq]

Hi

Again to re-go over what has been said in the past:

Unless they start filling the “extra” bits on the WWVB signal with something 
(are they doing this ) the whole modulation pattern is predictable. Once
you know what time it is “now” what happens from then on can all be calculated. 
I believe TVB has already done this part of it.

A “proper” receiver might take the AM and PM modulation signals and generate 
an “expected” signal from them once the time now is known. Correlating against 
that signal would seem to be the way to get this done. 

The one thing the Everest chips do indeed do is demonstrate that initial signal 
acquisition can be done under really awful conditions. Getting the same info 
off 
of WWVB with AM only …. not so much ….At least not so much with a receiver 
chip that is out on the market. 

Bob

> On Dec 4, 2018, at 4:21 PM, Attila Kinali  wrote:
> 
> Moin,
> 
> On Mon, 3 Dec 2018 18:11:30 -0800
> "Tom Van Baak"  wrote:
> 
>> At long last, a complete WWVB 60 kHz BPSK dev board is available:
>> 
>> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
>> 
>> Note it includes the antenna(s). Also has links to documentation.
> 
> 
> As this is becoming a topic again, and the EverSet people still
> claim that the BPSK modulation of WWVB makes it more resilient
> to jamming and easier to receive, I would like to restate
> what I've written some years ago [1,2]:
> 
> BPSK by itself does not improve timing. At most it improves reception
> by having a constant power envelope. But in case of WWVB, where
> the AM modulation is still kept, this is not the case. The phase
> changes do not help reception at all. In order to help reception,
> one needs to send a _known_ bit string in order for a corrolator
> in the receiver to pick the signal out of the noise. The only
> known bits in the BPSK signal are the first 12 bits of each minute.
> Compare this to DCF77 which encodes 512 bits every _second_.
> Ie while DCF77 gets something like 10-20dB  easier to pick out
> of noise, but when using BPSK, WWVB gets... uhmm..  zero improvement.
> 
> All the BPSK modulation of WWVB does is
> 1) Make the signal unusable for any carrier phase tracking receiver
> 2) Add a second type of bit stream onto the signal for additional
>   information to be encoded
> 3) Generate a revenue stream for companies who sell new WWVB receivers.
> 
> For more information, read [2]
> 
>   Attila Kinali
> 
> [1] https://www.febo.com/pipermail/time-nuts/2013-July/060456.html
> [2] https://www.febo.com/pipermail/time-nuts/2013-July/060471.html
> 
> 
> -- 
>   The bad part of Zurich is where the degenerates
>throw DARK chocolate at you.
> 
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Re: [time-nuts] new WWVB BPSK dev board

[Gregory Maxwell]

On Tue, Dec 4, 2018 at 9:22 PM Attila Kinali  wrote:
> known bits in the BPSK signal are the first 12 bits of each minute.

This seems transparently incorrect to me.  If your receiver has access
to only a tiny chunk of signal and no idea of anything else then yes,
but that isn't a realistic restriction.  Given that we know the signal
is a clock all the bits are almost perfectly predictable.  Unless I'm
confused about something about the signal.

The result is that you have some additional delay in learning the
carrier phase-- since an optimal decoder will make use of both past
and future signal to predict the bitstream, but that isn't really any
challenge against the PLL time constants that would be used.

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Re: [time-nuts] new WWVB BPSK dev board

[Bob kb8tq]

Hi

So, backing off a bit:

Assuming you are going to compare two data points a bit over 24 hours apart 
(100,000 seconds):

Accuracy of reading pairResult pp   Result 
sci

100 ms  1 ppm   1x10^-6
10 ms   100 ppb 1x10^-7
1 ms10 ppb  1x10^-8
100 us  1 ppb   1x10^-9
10 us   100 ppt 1x10^-10
1 us10 ppt  
1x10^-11

At 100 ms, you need to go for a *lot* of days before you get out of the “that’s 
interesting ….. yawn …”
category. Since it’s a pair you are concerned about, each might have a 50 ms 
error to get you to the
100 ms total. It’s still plenty good enough for a typical wall clock. 

At one day you don’t cross into “as good as a free running Rb” territory until 
you get below 100 us. 
That’s also the point you hit roughly the typical GPS module’s performance at 1 
second. 
If you want to get a “Time Nuts” grade solution, microseconds are indeed the 
units to worry about.

Assuming you hit can 100 us per pair, and want to get into the 1 to 10 ppt 
range, you are out around 
100 days for each “run”. That seems like a long time to wait. 

Since one period is 16.667 us, hitting well below 100 us implies keeping track 
of which cycle is which. Getting
to 10 us is just above a 180 degree phase error and 1 us is still above 10 
degrees. 

I’d say that for a practical “Time Nut" device … you need the equivalent of 
cycle tracking at the very least. 

Indeed, as mentioned by … somebody …. this all can be done and … ummm …. has 
been done for similar
signals by …errr …somebody :)

Bob

> On Dec 4, 2018, at 3:08 PM, David G. McGaw  
> wrote:
> 
> That is the specified jitter.  They have also said in communications that it 
> has about 50mS resolution.  That is as close as they are willing to say a 
> system can be synchronized with it.  Perhaps someone will discover a clever 
> way to enhance that.
> 
> BTW, I have been told it has also been successfully tested for lock in 
> Brazil.  Is there anyone in Australia want to give it a try?  Perth is almost 
> directly opposite Fort Collins.  :-)
> 
> David N1HAC
> 
> 
> On 12/4/18 2:00 PM, Hal Murray wrote:
> 
> 
> 
> 
> As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
> Time-Nut is looking for.
> 
> 
> 
> There is no problem with a delay as long as it is constant.  If I know what it
> is, then I can correct for it.
> 
> The problem is the noise/jitter on the delay.  I'm sure somebody will have
> data soon.
> 
> 
> 
> 
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Re: [time-nuts] new WWVB BPSK dev board

[Attila Kinali]

Moin,

On Mon, 3 Dec 2018 18:11:30 -0800
"Tom Van Baak"  wrote:

> At long last, a complete WWVB 60 kHz BPSK dev board is available:
> 
> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
> 
> Note it includes the antenna(s). Also has links to documentation.


As this is becoming a topic again, and the EverSet people still
claim that the BPSK modulation of WWVB makes it more resilient
to jamming and easier to receive, I would like to restate
what I've written some years ago [1,2]:

BPSK by itself does not improve timing. At most it improves reception
by having a constant power envelope. But in case of WWVB, where
the AM modulation is still kept, this is not the case. The phase
changes do not help reception at all. In order to help reception,
one needs to send a _known_ bit string in order for a corrolator
in the receiver to pick the signal out of the noise. The only
known bits in the BPSK signal are the first 12 bits of each minute.
Compare this to DCF77 which encodes 512 bits every _second_.
Ie while DCF77 gets something like 10-20dB  easier to pick out
of noise, but when using BPSK, WWVB gets... uhmm..  zero improvement.

All the BPSK modulation of WWVB does is
1) Make the signal unusable for any carrier phase tracking receiver
2) Add a second type of bit stream onto the signal for additional
   information to be encoded
3) Generate a revenue stream for companies who sell new WWVB receivers.

For more information, read [2]

Attila Kinali

[1] https://www.febo.com/pipermail/time-nuts/2013-July/060456.html
[2] https://www.febo.com/pipermail/time-nuts/2013-July/060471.html


-- 
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throw DARK chocolate at you.

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Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 12:21 PM, Bob kb8tq wrote:

Hi

We’ve been chatting about how drop dead simple it is to spend a couple minutes 
and come
up with a SDR for the new modulation for …. ummm ….. errr …. how many years 
now? :)
So far not a lot has turned up.


if someone will digitize the signal at some reasonable data rate and bit 
depth and send me some minutes of data, I'll see if I can code up a 
simple decoder that would run on a low end processor.


It's just BPSK at 1 bit/second, after all.

I maintain that it's the lack of a cheap RF front end that is the sticky 
point.





Bob


On Dec 4, 2018, at 3:14 PM, Poul-Henning Kamp  wrote:


In message <63462681-f5d7-0282-ef5b-82e8332d0...@dartmouth.edu>, "David G. 
McGaw" writes:


BTW, I have been told it has also been successfully tested for lock in Brazil.  
Is there anyone in Australia want to give it a try?  Perth is almost directly 
opposite Fort Collins.  :-)


Write a WWVB extension to KiwiSDR so you can try it all over the world ?


--
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
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Re: [time-nuts] new WWVB BPSK dev board

[Poul-Henning Kamp]

>We’ve been chatting about how drop dead simple it is to spend a couple minutes 
>and come
>up with a SDR for the new modulation for …. ummm ….. errr …. how many years 
>now? :)
>So far not a lot has turned up.

All I can say is that people dont know what they're missing ;-)


-- 
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Re: [time-nuts] new WWVB BPSK dev board

[Bob kb8tq]

Hi

We’ve been chatting about how drop dead simple it is to spend a couple minutes 
and come
up with a SDR for the new modulation for …. ummm ….. errr …. how many years 
now? :)
So far not a lot has turned up.

Bob

> On Dec 4, 2018, at 3:14 PM, Poul-Henning Kamp  wrote:
> 
> 
> In message <63462681-f5d7-0282-ef5b-82e8332d0...@dartmouth.edu>, "David G. 
> McGaw" writes:
> 
>> BTW, I have been told it has also been successfully tested for lock in 
>> Brazil.  Is there anyone in Australia want to give it a try?  Perth is 
>> almost directly opposite Fort Collins.  :-)
> 
> Write a WWVB extension to KiwiSDR so you can try it all over the world ?
> 
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> 
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Re: [time-nuts] new WWVB BPSK dev board

[Poul-Henning Kamp]

In message <63462681-f5d7-0282-ef5b-82e8332d0...@dartmouth.edu>, "David G. 
McGaw" writes:

>BTW, I have been told it has also been successfully tested for lock in Brazil. 
> Is there anyone in Australia want to give it a try?  Perth is almost directly 
>opposite Fort Collins.  :-)

Write a WWVB extension to KiwiSDR so you can try it all over the world ?


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

That is the specified jitter.  They have also said in communications that it 
has about 50mS resolution.  That is as close as they are willing to say a 
system can be synchronized with it.  Perhaps someone will discover a clever way 
to enhance that.

BTW, I have been told it has also been successfully tested for lock in Brazil.  
Is there anyone in Australia want to give it a try?  Perth is almost directly 
opposite Fort Collins.  :-)

David N1HAC


On 12/4/18 2:00 PM, Hal Murray wrote:




As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
Time-Nut is looking for.



There is no problem with a delay as long as it is constant.  If I know what it
is, then I can correct for it.

The problem is the noise/jitter on the delay.  I'm sure somebody will have
data soon.




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Re: [time-nuts] new WWVB BPSK dev board

[Hal Murray]

> As was said, IRQ delay is +/-100 mS from the second edge, hardly what a
> Time-Nut is looking for. 

There is no problem with a delay as long as it is constant.  If I know what it 
is, then I can correct for it.

The problem is the noise/jitter on the delay.  I'm sure somebody will have 
data soon.


-- 
These are my opinions.  I hate spam.




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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

As was said, IRQ delay is +/-100 mS from the second edge, hardly what a 
Time-Nut is looking for.

David


On 12/4/18 1:07 PM, Hal Murray wrote:
>> The one thing I wish is that there were access to the synchronized  analog
>> signal and/or a 1PPS.  Even a top of the minute would be useful.   It only
>> has the I2C digital interface.
> It also has an IRQ signal.
>
> The data sheet said it's 100 ms after the second, but I didn't see any
> accuracy info but I didn't look carefully.
>
>

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Re: [time-nuts] new WWVB BPSK dev board

[Hal Murray]

> The one thing I wish is that there were access to the synchronized  analog
> signal and/or a 1PPS.  Even a top of the minute would be useful.   It only
> has the I2C digital interface. 

It also has an IRQ signal.

The data sheet said it's 100 ms after the second, but I didn't see any 
accuracy info but I didn't look carefully.


-- 
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Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 9:00 AM, Tim Shoppa wrote:

Because of the Q of WWVB's transmit antenna (at least 300 by my back of the
envelope estimates), I don't think we could ever claim a WWVB PPS edge
sharper than 5 milliseconds and that might be optimistic.



Sure you can.. you do a matched filter to the waveform, so you're not 
just looking at a single zero crossing or cycle.  Getting fraction of a 
degree phase accuracy from a strong signal is entirely possible.


A Q of 300 implies a bandwidth of 200Hz, which would, if a single 
section, be a delay of a few milliseconds.  But that delay should be 
constant. What might be the limit on precision is whether the delay 
through the antenna and the ultimate radiated phase changes with, say, 
temperature or soil properties.





Tim N3QE

On Tue, Dec 4, 2018 at 11:49 AM Bob kb8tq  wrote:


Hi

The I2C clock rate is going to matter a bit in terms of what you can
achieve.
Since the device is targeted at low power, the max practical baud rate may
not be very high. I2C can have a lot of wait in it ... There are a lot of
registers
dumped after each “reception attempt”.

There also is the basic question of how the IRQ flag relates to the time
the
chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing.

None of this is likely to be an issue in a wall clock. If they can run at
a “tens of ms”
sort of level that’s more than good enough. We really want to get to
microseconds
don’t we :)

Bob


On Dec 4, 2018, at 11:25 AM, Majdi S. Abbas  wrote:

$69 CAD is roughly $50 USD.

Expensive for what it is but easier to work with than gutting a working

clock and no more expensive.


I ordered one.  Curious to see what sort of precision we can get from an

i2c interface.


If nothing else I suppose I can toss a six digit i2c 7 segment module at

it and roll my own WWVB desk clock.


—msa


On Dec 4, 2018, at 07:50, paul swed  wrote:

I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a

bit

off.
Regards
Paul
WB8TSL




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Re: [time-nuts] new WWVB BPSK dev board

[jimlux]

On 12/4/18 8:59 AM, Adrian Godwin wrote:

I understand why a low-volume shipment of what started as a board costing a
few pennies costs $50, but does that simply mean that low-cost parts aren't
the right answer for this sort of application ?

How would an SDR based on a raspberry pi zero, a suitable ADC and a tuned
rx circuit compare ?




"suitable ADC" and "tuned Rx circuit" would greatly interact.. the more 
narrow band your Rx, the fewer bits you'd need in your ADC - The Teensy 
($20 arduino clone) can sample at well over 100ksps with a 16 bit (13-14 
ENOB) differential input, and I'll bet you could make a simple PSK 
demodulator in software, either on the Teensy or on the host PC  (which 
could be a RPi or Beagle) connected via USB.



https://www.pjrc.com/store/teensy32.html

They also sell a higher performance audio interface that might be useful:
https://www.pjrc.com/store/teensy3_audio.html
Although it's 44.1 kHz sample rate - but might actually support other rates.


So the real question is where can you find an inexpensive 60kHz front 
end amplifier.


The computer (whether arduino, teensy, beagle, or Rpi) isn't the 
limiting thing, it's the RF to digital interface. -


Find a $20 60kHz narrow band receiver/ADC , and the rest is straightforward.




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Re: [time-nuts] new WWVB BPSK dev board

[John Ackermann. N8UR]

I ordered one, too.  It looks like there's an IRQ line that goes low +/- 100 ms 
of the second mark.  It will be interesting to see how stable that is in real 
life.

On Dec 4, 2018, 11:27 AM, at 11:27 AM, "Majdi S. Abbas"  wrote:
>$69 CAD is roughly $50 USD.
>
>Expensive for what it is but easier to work with than gutting a working
>clock and no more expensive.
>
>I ordered one.  Curious to see what sort of precision we can get from
>an i2c interface.
>
>If nothing else I suppose I can toss a six digit i2c 7 segment module
>at it and roll my own WWVB desk clock.
>
>—msa
>
>> On Dec 4, 2018, at 07:50, paul swed  wrote:
>> 
>> I assume thats exactly the case. I also thought it was pretty high.
>> The actual clocks are about $50 or less I believe. So the board seems
>a bit
>> off.
>> Regards
>> Paul
>> WB8TSL
>> 
>>> On Tue, Dec 4, 2018 at 12:03 AM Eric Garner 
>wrote:
>>> 
>>> This seems relatively expensive for a little wirebonded board of
>this type.
>>> It seems like the sort of thing that you would normally find on
>aliexpress
>>> or ebay for a few dollars.
>>> 
>>> It it because the es100 is otherwise unobtanium?
>>> 
>>> Eric
>>> 
 On Mon, Dec 3, 2018, 6:12 PM Tom Van Baak wrote:
 
 At long last, a complete WWVB 60 kHz BPSK dev board is available:
 
 
 
>>>
>https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
 
 Note it includes the antenna(s). Also has links to documentation.
 
 It would be very nice if a bunch of time nuts around the country
>played
 with these and reported results.
 
 Prior to this, the only device that you could buy which used the
>enhanced
 WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It
>was not
 developer friendly, so a dev board with the Everset ES100 chip is
>good
>>> news.
 
 The maker / hacker / Arduino crowd may enjoy a fresh source of
>accurate
 time; something independent of GPS or NTP. Some technical postings
>about
 reception quality, acquisition speed, and timing precision would be
>most
 welcome.
 
 /tvb
 
 
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Re: [time-nuts] new WWVB BPSK dev board

[Tim Shoppa]

Because of the Q of WWVB's transmit antenna (at least 300 by my back of the
envelope estimates), I don't think we could ever claim a WWVB PPS edge
sharper than 5 milliseconds and that might be optimistic.

Tim N3QE

On Tue, Dec 4, 2018 at 11:49 AM Bob kb8tq  wrote:

> Hi
>
> The I2C clock rate is going to matter a bit in terms of what you can
> achieve.
> Since the device is targeted at low power, the max practical baud rate may
> not be very high. I2C can have a lot of wait in it ... There are a lot of
> registers
> dumped after each “reception attempt”.
>
> There also is the basic question of how the IRQ flag relates to the time
> the
> chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing.
>
> None of this is likely to be an issue in a wall clock. If they can run at
> a “tens of ms”
> sort of level that’s more than good enough. We really want to get to
> microseconds
> don’t we :)
>
> Bob
>
> > On Dec 4, 2018, at 11:25 AM, Majdi S. Abbas  wrote:
> >
> > $69 CAD is roughly $50 USD.
> >
> > Expensive for what it is but easier to work with than gutting a working
> clock and no more expensive.
> >
> > I ordered one.  Curious to see what sort of precision we can get from an
> i2c interface.
> >
> > If nothing else I suppose I can toss a six digit i2c 7 segment module at
> it and roll my own WWVB desk clock.
> >
> > —msa
> >
> >> On Dec 4, 2018, at 07:50, paul swed  wrote:
> >>
> >> I assume thats exactly the case. I also thought it was pretty high.
> >> The actual clocks are about $50 or less I believe. So the board seems a
> bit
> >> off.
> >> Regards
> >> Paul
> >> WB8TSL
> >>
>
>
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Re: [time-nuts] new WWVB BPSK dev board

[Adrian Godwin]

I understand why a low-volume shipment of what started as a board costing a
few pennies costs $50, but does that simply mean that low-cost parts aren't
the right answer for this sort of application ?

How would an SDR based on a raspberry pi zero, a suitable ADC and a tuned
rx circuit compare ?



On Tue, Dec 4, 2018 at 4:54 PM David G. McGaw 
wrote:

> It does a very good job of pulling the signal out of the noise.  It
> works in NH, traditionally a fringe region, in all but the most shielded
> of rooms.  I also had occasion to test it for Everset in Kangerlussuaq,
> Greenland.  I found it had no trouble acquiring at any time of the day.
> If the ES100 does not do well enough for you, there is supposedly an
> ES200 available that uses a longer sequence for even more sensitivity.
>
> The one thing I wish is that there were access to the synchronized
> analog signal and/or a 1PPS.  Even a top of the minute would be useful.
> It only has the I2C digital interface.
>
> 73,
>
> David N1HAC
>
>
> On 12/4/18 11:35 AM, Tim Shoppa wrote:
> > Thanks for the heads up Tom! I ordered one and if it comes before the end
> > of the year I may have some time over the holidays to do acquisition test
> > from Maryland and maybe some cross-comparison with GPS PPS.
> >
> > Here in Maryland I have somewhat unreliable reception on commercial
> > non-BPSK WWVB clocks at my house. My Casio Waveceptor watch is 99%+
> > reliable when I'm asleep on the 2nd floor but much less likely to work in
> > the basement. I can reliably hear the amplitude-keyed WWVB carrier on a
> LF
> > receiver with a homebrew loop (about 3 foot by 3 foot) in the evenings
> but
> > it takes some imagination to think I can hear it during the daytime.
> >
> > Tim N3QE
> >
> > On Mon, Dec 3, 2018 at 9:12 PM Tom Van Baak  wrote:
> >
> >> At long last, a complete WWVB 60 kHz BPSK dev board is available:
> >>
> >>
> >>
> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
> >>
> >> Note it includes the antenna(s). Also has links to documentation.
> >>
> >> It would be very nice if a bunch of time nuts around the country played
> >> with these and reported results.
> >>
> >> Prior to this, the only device that you could buy which used the
> enhanced
> >> WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
> >> developer friendly, so a dev board with the Everset ES100 chip is good
> news.
> >>
> >> The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
> >> time; something independent of GPS or NTP. Some technical postings about
> >> reception quality, acquisition speed, and timing precision would be most
> >> welcome.
> >>
> >> /tvb
> >>
> >>
> >> ___
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> >>
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Re: [time-nuts] new WWVB BPSK dev board

[David G. McGaw]

It does a very good job of pulling the signal out of the noise.  It 
works in NH, traditionally a fringe region, in all but the most shielded 
of rooms.  I also had occasion to test it for Everset in Kangerlussuaq, 
Greenland.  I found it had no trouble acquiring at any time of the day.  
If the ES100 does not do well enough for you, there is supposedly an 
ES200 available that uses a longer sequence for even more sensitivity.

The one thing I wish is that there were access to the synchronized 
analog signal and/or a 1PPS.  Even a top of the minute would be useful.  
It only has the I2C digital interface.

73,

David N1HAC


On 12/4/18 11:35 AM, Tim Shoppa wrote:
> Thanks for the heads up Tom! I ordered one and if it comes before the end
> of the year I may have some time over the holidays to do acquisition test
> from Maryland and maybe some cross-comparison with GPS PPS.
>
> Here in Maryland I have somewhat unreliable reception on commercial
> non-BPSK WWVB clocks at my house. My Casio Waveceptor watch is 99%+
> reliable when I'm asleep on the 2nd floor but much less likely to work in
> the basement. I can reliably hear the amplitude-keyed WWVB carrier on a LF
> receiver with a homebrew loop (about 3 foot by 3 foot) in the evenings but
> it takes some imagination to think I can hear it during the daytime.
>
> Tim N3QE
>
> On Mon, Dec 3, 2018 at 9:12 PM Tom Van Baak  wrote:
>
>> At long last, a complete WWVB 60 kHz BPSK dev board is available:
>>
>>
>> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
>>
>> Note it includes the antenna(s). Also has links to documentation.
>>
>> It would be very nice if a bunch of time nuts around the country played
>> with these and reported results.
>>
>> Prior to this, the only device that you could buy which used the enhanced
>> WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
>> developer friendly, so a dev board with the Everset ES100 chip is good news.
>>
>> The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
>> time; something independent of GPS or NTP. Some technical postings about
>> reception quality, acquisition speed, and timing precision would be most
>> welcome.
>>
>> /tvb
>>
>>
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Re: [time-nuts] new WWVB BPSK dev board

[Bob kb8tq]

Hi

The I2C clock rate is going to matter a bit in terms of what you can achieve. 
Since the device is targeted at low power, the max practical baud rate may
not be very high. I2C can have a lot of wait in it ... There are a lot of 
registers 
dumped after each “reception attempt”. 

There also is the basic question of how the IRQ flag relates to the time the 
chip “sees”. If it’s actually WWVB time sync’d then that’s a useful thing. 

None of this is likely to be an issue in a wall clock. If they can run at a 
“tens of ms”
sort of level that’s more than good enough. We really want to get to 
microseconds 
don’t we :) 

Bob

> On Dec 4, 2018, at 11:25 AM, Majdi S. Abbas  wrote:
> 
> $69 CAD is roughly $50 USD.
> 
> Expensive for what it is but easier to work with than gutting a working clock 
> and no more expensive.
> 
> I ordered one.  Curious to see what sort of precision we can get from an i2c 
> interface.
> 
> If nothing else I suppose I can toss a six digit i2c 7 segment module at it 
> and roll my own WWVB desk clock.
> 
> —msa
> 
>> On Dec 4, 2018, at 07:50, paul swed  wrote:
>> 
>> I assume thats exactly the case. I also thought it was pretty high.
>> The actual clocks are about $50 or less I believe. So the board seems a bit
>> off.
>> Regards
>> Paul
>> WB8TSL
>> 


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Re: [time-nuts] new WWVB BPSK dev board

[Tim Shoppa]

Thanks for the heads up Tom! I ordered one and if it comes before the end
of the year I may have some time over the holidays to do acquisition test
from Maryland and maybe some cross-comparison with GPS PPS.

Here in Maryland I have somewhat unreliable reception on commercial
non-BPSK WWVB clocks at my house. My Casio Waveceptor watch is 99%+
reliable when I'm asleep on the 2nd floor but much less likely to work in
the basement. I can reliably hear the amplitude-keyed WWVB carrier on a LF
receiver with a homebrew loop (about 3 foot by 3 foot) in the evenings but
it takes some imagination to think I can hear it during the daytime.

Tim N3QE

On Mon, Dec 3, 2018 at 9:12 PM Tom Van Baak  wrote:

> At long last, a complete WWVB 60 kHz BPSK dev board is available:
>
>
> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
>
> Note it includes the antenna(s). Also has links to documentation.
>
> It would be very nice if a bunch of time nuts around the country played
> with these and reported results.
>
> Prior to this, the only device that you could buy which used the enhanced
> WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
> developer friendly, so a dev board with the Everset ES100 chip is good news.
>
> The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
> time; something independent of GPS or NTP. Some technical postings about
> reception quality, acquisition speed, and timing precision would be most
> welcome.
>
> /tvb
>
>
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Re: [time-nuts] new WWVB BPSK dev board

[paul swed]

Majdi good for you. You will have fun. OK precision thats a slippery slope.
The documentation will indicate the sequence time and length and as I
recall the chip produces a result every 90 seconds using the long phase.
There is a short phase after you have acquired that is something like 30
seconds. But I recall it was tricky aligning to the second. That was the
BPSK edge. Anyhow it does work.
I hear they ship some arduino code with it. That would be fun to look at. I
used whats was called a SXB at the time. Worked fine.
Regards
Paul

On Tue, Dec 4, 2018 at 11:26 AM Majdi S. Abbas  wrote:

> $69 CAD is roughly $50 USD.
>
> Expensive for what it is but easier to work with than gutting a working
> clock and no more expensive.
>
> I ordered one.  Curious to see what sort of precision we can get from an
> i2c interface.
>
> If nothing else I suppose I can toss a six digit i2c 7 segment module at
> it and roll my own WWVB desk clock.
>
> —msa
>
> > On Dec 4, 2018, at 07:50, paul swed  wrote:
> >
> > I assume thats exactly the case. I also thought it was pretty high.
> > The actual clocks are about $50 or less I believe. So the board seems a
> bit
> > off.
> > Regards
> > Paul
> > WB8TSL
> >
> >> On Tue, Dec 4, 2018 at 12:03 AM Eric Garner  wrote:
> >>
> >> This seems relatively expensive for a little wirebonded board of this
> type.
> >> It seems like the sort of thing that you would normally find on
> aliexpress
> >> or ebay for a few dollars.
> >>
> >> It it because the es100 is otherwise unobtanium?
> >>
> >> Eric
> >>
> >>> On Mon, Dec 3, 2018, 6:12 PM Tom Van Baak  >>>
> >>> At long last, a complete WWVB 60 kHz BPSK dev board is available:
> >>>
> >>>
> >>>
> >>
> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
> >>>
> >>> Note it includes the antenna(s). Also has links to documentation.
> >>>
> >>> It would be very nice if a bunch of time nuts around the country played
> >>> with these and reported results.
> >>>
> >>> Prior to this, the only device that you could buy which used the
> enhanced
> >>> WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was
> not
> >>> developer friendly, so a dev board with the Everset ES100 chip is good
> >> news.
> >>>
> >>> The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
> >>> time; something independent of GPS or NTP. Some technical postings
> about
> >>> reception quality, acquisition speed, and timing precision would be
> most
> >>> welcome.
> >>>
> >>> /tvb
> >>>
> >>>
> >>> ___
> >>> time-nuts mailing list -- time-nuts@lists.febo.com
> >>> To unsubscribe, go to
> >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> >>> and follow the instructions there.
> >>>
> >> ___
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> >> and follow the instructions there.
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> > and follow the instructions there.
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Re: [time-nuts] new WWVB BPSK dev board

[Majdi S. Abbas]

$69 CAD is roughly $50 USD.

Expensive for what it is but easier to work with than gutting a working clock 
and no more expensive.

I ordered one.  Curious to see what sort of precision we can get from an i2c 
interface.

If nothing else I suppose I can toss a six digit i2c 7 segment module at it and 
roll my own WWVB desk clock.

—msa

> On Dec 4, 2018, at 07:50, paul swed  wrote:
> 
> I assume thats exactly the case. I also thought it was pretty high.
> The actual clocks are about $50 or less I believe. So the board seems a bit
> off.
> Regards
> Paul
> WB8TSL
> 
>> On Tue, Dec 4, 2018 at 12:03 AM Eric Garner  wrote:
>> 
>> This seems relatively expensive for a little wirebonded board of this type.
>> It seems like the sort of thing that you would normally find on aliexpress
>> or ebay for a few dollars.
>> 
>> It it because the es100 is otherwise unobtanium?
>> 
>> Eric
>> 
>>> On Mon, Dec 3, 2018, 6:12 PM Tom Van Baak >> 
>>> At long last, a complete WWVB 60 kHz BPSK dev board is available:
>>> 
>>> 
>>> 
>> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
>>> 
>>> Note it includes the antenna(s). Also has links to documentation.
>>> 
>>> It would be very nice if a bunch of time nuts around the country played
>>> with these and reported results.
>>> 
>>> Prior to this, the only device that you could buy which used the enhanced
>>> WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
>>> developer friendly, so a dev board with the Everset ES100 chip is good
>> news.
>>> 
>>> The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
>>> time; something independent of GPS or NTP. Some technical postings about
>>> reception quality, acquisition speed, and timing precision would be most
>>> welcome.
>>> 
>>> /tvb
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe, go to
>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>>> and follow the instructions there.
>>> 
>> ___
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>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
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Re: [time-nuts] new WWVB BPSK dev board

[paul swed]

I assume thats exactly the case. I also thought it was pretty high.
The actual clocks are about $50 or less I believe. So the board seems a bit
off.
Regards
Paul
WB8TSL

On Tue, Dec 4, 2018 at 12:03 AM Eric Garner  wrote:

> This seems relatively expensive for a little wirebonded board of this type.
> It seems like the sort of thing that you would normally find on aliexpress
> or ebay for a few dollars.
>
> It it because the es100 is otherwise unobtanium?
>
> Eric
>
> On Mon, Dec 3, 2018, 6:12 PM Tom Van Baak 
> > At long last, a complete WWVB 60 kHz BPSK dev board is available:
> >
> >
> >
> https://universal-solder.ca/product/everset-es100-cob-wwvb-60khz-bpsk-receiver-kit-with-2-antennas/
> >
> > Note it includes the antenna(s). Also has links to documentation.
> >
> > It would be very nice if a bunch of time nuts around the country played
> > with these and reported results.
> >
> > Prior to this, the only device that you could buy which used the enhanced
> > WWVB format was the La Crosse 404-1235UA-SS UltrAtomic clock. It was not
> > developer friendly, so a dev board with the Everset ES100 chip is good
> news.
> >
> > The maker / hacker / Arduino crowd may enjoy a fresh source of accurate
> > time; something independent of GPS or NTP. Some technical postings about
> > reception quality, acquisition speed, and timing precision would be most
> > welcome.
> >
> > /tvb
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to
> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
> >
> ___
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> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
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[time-nuts] new WWVB BPSK dev board

[gandalfg8--- via time-nuts]

Hi Paul,



It was shifted over 11 years ago, very obligingly timed to follow my move from 
the South East to Scotland:-),

so I suspect any resulting propogational changes would have been well 
documented by now.



Nigel GM8PZR



Hi thank you Bob for the mail 

Do you realise the 60 Khz Transmitter in the UK was moved from Rugby in the
centre of England north by more than 200 miles 
Paul 
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Re: [time-nuts] Ashtech Z12T

[Michael Wouters]

Hello JF

(Ccing to time nuts because probably still of interest)
The TTR6 is a single channel receiver so you had to install an observing
schedule appropriate to your geographical region, which specified which
satellite you would track at which time. The BIPM used to generate and
distribute these schedules every 6 months or so but stopped doing this 7?
years ago - I think this is what you mean by "ephemerides".

If you have N satellites tracked then you can reduce the time transfer
noise by sqrt(N) roughly speaking. You can either do common view, where you
match satellites at each location and time, and then take an average of the
differences, or all in view, where you average all of the satellites
visible at each location, and then difference. Common view gives you less
noise (because of better cancellation of eg the effects of the ionosphere)
on short baselines. However as the baseline increases in length, the number
of satellites in common view decreases and the statistical noise increases.
At distances of a few thousand km, all in view starts to win because more
satellites are used. You can improve the processing by doing things like
weighting  the satellites according to their elevation.

The current best method of doing GNSS time-transfer is PPP or precise point
positioning, and is a form of all in view, with much better post-processing
that uses both code and phase observatIons. You can do this with the
Septentrio receivers. But CGGTTS-based time transfer is still used in the
timing community.

Cheers
Michael


On Tue, 4 Dec 2018 at 9:19 pm, JF PICARD  wrote:

> Hello,
>
> Thank you very much for your explanations but, as a newbie in this immense
> domain, I have got some questions. With the Allen Osborne TTR-6 we received
> from the LNE SYRTE (french observatory)  and loaded the ephemiredes (data
> about the GPS satellites passing above us the next week or month) and we
> will follow satellite X, the Y... , we sent our received data and we got
> the data from LNE for the same satellite...
> How does the actual system operate with several satellites ? I haven't
> seen any mention (quick overlook in the data sheet) neither in the
> Septentrio nor in the NVS...
>
> Cheers.
>
> JF
> 
> On Mon, 12/3/18, Michael Wouters  wrote:
>
>  Subject: Re: [time-nuts] Ashtech Z12T
>  To: "Discussion of precise time and frequency measurement" <
> time-nuts@lists.febo.com>, "JF PICARD" 
>  Date: Monday, December 3, 2018, 8:42 PM
>
>  Hello
>  There are many alternatives to the
>  Z12T. It all depends on your budget. I am guessing that you
>  want to establish legal traceability to your local UTC, is
>  that right?
>  Starting
>  at the top end, you can buy complete systems from Dicom and
>  Piktime. These cost about $25K and $40K respectively. These
>  are multi-frequency, multi-GNSS systems.
>  There are also some cheaper, single
>  frequency systems (GPS only)  available too, from a company
>  in Japan and one in the U.K. Just search for "time
>  transfer system".
>  Some NMIs in countries like Canada,
>  Australia, Japan, ... offer remote calibration services of
>  the kind you want to set up. These  are too far away for
>  common view but I suppose all in view would be the method in
>  this case ( you would still have traceability to your UTC
>  via the CIPM Mutual Recognition Agreement). Costs are
>  something like $5K per year, in addition to the
>  hardware.
>  You can just
>  buy a shiny new time-transfer receiver like the Septentrio
>  PolaRx5TRPRO with a geodetic antenna for about $20K. These
>  are the most popular in the timing community at the moment.
>  But other receivers like Javad and Trimble are good
>  too.
>  If single
>  frequency performance is good enough, and you're willing
>  to do a bit of work setting up software, then the really low
>  cost solution is something like the software from www.openttp.orgThe
>  main receiver supported, the NVS NV08C is less than $100.
>  You can get accurate antenna positions from this receiver in
>  a base rover configuration. All the rest is post processing
>  and there are various options here. You will also need a
>  counter/timer and the low cost solution here is the TAPR
>  TICC, which is also supported by OpenTTP.
>  CheersMichael
>
>  On Mon, 3
>  Dec 2018 at 10:21 pm, JF PICARD via time-nuts 
>  wrote:
>  Thank you
>  for answer and sorry for delay. Purpose is simultaneous view
>  of GPS satellites with the french official time laboratory
>  LNE SYRTE . The corrections factors from the laboratory will
>  enable to get with our high performance cesium about 5.
>  10-13  . Today the cesium is running alone. Discussion with
>  some people involved in this worlwide common practice spoke
>  about the Z12T but if there is anything more modern..
>
>  
>
>  On Wed, 11/28/18, Tom Van Baak 
>  wrote:
>
>
>
>   Subject: Re: [time-nuts] Ashtech Z12T
>
>   To: "Discussion of