[time-nuts] Re: GPS failed

[Scott McGrath via time-nuts]

I’m going to bring up jamming here as 1) i live directly under a military air 
route.  2) a local OTR  trucker brings regularly scheduled jamming when he 
leaves/arrives home.

Your client could also be in proximity to a ‘prepper’ who is running a GPS 
jammer to prevent ‘three letter agencies’ from tracking them.   Or a trucker 
doing the same and forgetting to shut down their jammer.   GPS jammers are 
available ‘under the counter’ at virtually every truck stop in the US.

Yes it’s highly illegal and disrespectful of other system users and in the 
prepper case will eventually attract the attention of those very authorities 
they wished to avoid.

A reasonable way to check for jamming is the FAA ADS-B system.   if a ADS-B 
outage exists in same area and time as client sees GPS failure Client is likely 
to be experiencing jamming as ADS-B utilizes onboard GPS receivers to report 
aircraft position using a transmitter at   1090MHz in real time instead of 
depending on ATC radar to trigger a transponder.

Link to the FAA ADS-B outage system below 

https://sapt.faa.gov/outages.php?outageType=129001450=0.5





Content by Scott
Typos by Siri

On Jul 12, 2022, at 3:20 AM, Matthias Welwarsky via time-nuts 
 wrote:

Hi,

if you're worried about in-band interference, the 23cm HAM radio band is 
reasonably close to the L1 GPS frequency. When I was still active in packet 
radio back in the days, our digipeater DB0DAR lost an interlink due to 
interference with a precision GPS receiver in use by another university 
institute. We had to shut it down. I think they operated a DGPS site at the 
time and our link traffic caused errors in the correction data. Or something.

BR,
Matthias

On Montag, 11. Juli 2022 01:19:18 CEST skipp Isaham via time-nuts wrote:
> Hello to the Group,
> 
> I'd like to get some opinions and war stories regarding GPS reliability at
> high RF level and elevation locations.
> 
> Background:  Three different hill-top GPS receivers, all different types,
> using different antennas mounted on an outside fixiture, plain view of the
> open sky, all stopped working.
> 
> Test antennas were brought in and placed on a fixture well away from the
> original antennas, the recevers went back in to capture and lock.
> 
> From what I understand, the original antennas are what I would call straight
> preamp with no pre-selection / filtering.
> 
> The ordered and now inbound replacements are said to contain a SAW filter
> system. It is the intent of the client to just place these "improved
> antennas" in to service and get on with life.
> 
> I would suspect a GPS antenna (and receiver) could be subject to RF overload
> or blocking, however, we're assuming nothing major has changed at the site,
> nor any nearby location.  One might think there are more GPS receivers
> being pushed out of reliable operation by the world around them, I'm just
> not hearing those stories from a lot of people using them (GPS receivers).
> 
> Any new install GPS receiver antenna ordered will/should contain some
> pre-selection to potentially avoid a problem, even some years down the
> road? Seems like that's where things are going... no more off the shelf,
> wide band, (hot) preamplified GPS antennas in busy locations?
> 
> Thank you in advance for any related comments and/or opions ...
> 
> cheers,
> 
> skipp
> 
> skipp025 at jah who dot calm
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[time-nuts] Re: QM10 Quartz chronometer

[Scott McGrath]

Usually in analog quartz clocks oscillator frequency is around 32khz

Content by Scott
Typos by Siri

On Nov 26, 2021, at 9:09 AM, Peter Torry via time-nuts 
 wrote:

Hello list,

I am restoring a Seiko Quartz QM10 Marine Chronometer that is currently 
inoperative. Preliminary investigations would indicate that the oscillator (TO5 
header) isn't functioning therefore I am seeking any information as to its 
nominal frequency and whether it is just a crystal or an oscillator. I can 
follow the cmos dividers OK but a schematic diagram would be most useful.

Any help or pointers much appreciated.

Kind regards

Peter   UK
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[time-nuts] Re: in-ground clock room

[Scott McGrath]

Rather than custom casting a structure you might want to consider use of a 
precast concrete septic tank or transformer vault as cost will be much lower.

You will also need to consider waterproofing the tank it already has a layer of 
waterproofing but a couple of additional layers will probably be necessary as 
well as ensuring proper drainage around it as it will need to be both above 
local water table and be able to drain off percolating rainwater. 

You will also need to control temperature and humidity 

On Sep 9, 2021, at 12:03 PM, Joseph Gwinn  wrote:

On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-requ...@lists.febo.com 
wrote:
Re: time-nuts Digest, Vol 209, Issue 6


> --
>> Date: Wed, 8 Sep 2021 18:54:03 -0700
> From: Tom Van Baak 
> Subject: [time-nuts] in-ground clock room
> To: Discussion of precise time and frequency measurement
>
> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf19327...@leapsecond.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> I am considering a below ground "clock room" away from the house. This 
> will be for some low-drift quartz oscillators and also a couple of 
> precision pendulum clocks. The goal is long-term, unattended, and very 
> undisturbed operation.
> 
> For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So 
> that's vastly smaller than digging a basement, but much larger than 
> drilling a 8 inch round pipe. Digging down gives some natural isolation 
> and temperature regulation. A couple tons of concrete gives high 
> stability vertical walls for the pendulum clocks.
> 
> If any of you have personal or professional experience with the design 
> or construction of this sort of thing, especially experience with 
> precast (utility) vaults or poured concrete, please let me know.
> 
> In case this gets too off-topic for time-nuts, off-list email to me is 
> fine (t...@leapsecond.com).

As others have said, it may not be economically practical to build an 
underground clock room.

Assuming that you have a basement of other suitable room in your 
house, I'd suggest an insulated box or room containing a big lump of 
iron riding on an inner-tube suspension of some kind.   The big lump 
of iron can be a 500-pound truck engine head or block from a 
junkyard, steam cleaned (to remove oil) and painted (to keep the rust 
under control).  Drill and tap holes as needed for mounting.

This box/room plus block can be set up as a temperature-controlled 
oven with a few extra components, including a PID controller.

Bolt a thick plywood floor to the top of the iron hunk, and attach 
the clocks to this floor.

Joe Gwinn
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Re: [time-nuts] - LightSquared is back now called Ligado

[Scott McGrath]

What grade of receiver will this thing NOT break the Garmin stack in our flying 
club’s plane is a heck of a lot better than consumer grade GNSS but we’ll be 
line of sight to the transmitters

Sorry I miscopied the power specs but DbW is even worse.  I was visualizing 
microcells not full power base stations 

There is no doubt the FCC has been overrun by kleptocrats of late but that goes 
back to Chairman Powell.

I dont know how this was authorized as the carriers are collectively sitting on 
thousands of GHz of allocated bandwidth in the existing bands which they refuse 
to deploy.And they are poaching in the Wifi/ISM bands as well with LAA 
which once it comes up makes WiFi useless.  So there is no basis in reality for 
polluting a space based service due to a ‘shortage’ of spectrum.

US Govt needs to implement a use it or lose it policy on cell spectrum. Ie must 
deploy within 2 years or spectrum reverts back to US Govt.   or better yet.  
Refund the purchase of spectrum and rent it out.



On Apr 18, 2020, at 7:31 AM, bill  wrote:

Hi,
This is going to affect INMARSAT and Iridium satellite phone service as well.  
Does anyone know anything about this?

As I see it, putting such transmitters into operation will render consumer 
grade GNSS receivers unusable.  High-end survey and
reference receiving systems might have to be upgraded with sharper filtering 
(much more costly and bulky) to maintain reliability.
If Ligado transmitter spurious emission requirements at band edge will have to 
meet unrealistic requirements to prevent interference
with GNSS.  L-band satphone service could be completely cooked.

I guess the FCC suffers from being co-opted by the current crop of kleptocrats 
and incompetents that affect other branches of government as well..and not just 
in the USA!
Cheers,
Bill


> On 18.04.20 11:37, Dave B via time-nuts wrote:
> Hi.
> 
> Reading that web page, they are talking dBW levels, not dBm levels.
> Hopefully that is a typo, as 0dBW is of course 1000 times more than 0dBm.
> 
> 
> To quote from the page:-
> 
> The base-station power reduction is "from 32dBW to 9.8dBW," and Ligado
> committed to a 23MHz "guard-band using its own licensed spectrum to
> further separate its terrestrial base station transmissions from
> neighboring operation," the FCC said.
> 
> 32dBW if I'm not mistaken, is some 1500W !   9.8dBW is just under 10W.
> (Maybe someone costed the potential electric bill per site?)
> 
> 
> dBW is a common spec' in licensing forms, certainly over hear.
> 
> Even so, 9.8dBW from a femtocell (like a plug in wall wart sized thing)
> is going to really anger the tinfoil hat brigade.
> 
> 
> But anyway, what the hell is the point of a satellite based system, if
> you're going to pollute the downlink frequencies.  Even more so, when
> said satellite reception systems are working with signal levels close to
> the ambient noise anyway.
> 
> That, and isn't 5G intended for (among other things) mobile devices?
> That probably will be trying to use GPS etc as well.   Shoot in own foot
> time I think.
> 
> 
> Regards.
> 
> Dave B.
> 
> 
> 
>> On 18/04/2020 00:56, time-nuts-requ...@lists.febo.com wrote:
>> Message: 1
>> Date: Fri, 17 Apr 2020 13:37:26 -0400
>> From: Scott McGrath 
>> To: time-nuts@lists.febo.com
>> Cc: Mike Rogers 
>> Subject: [time-nuts] LightSquared is back now called Ligado
>> Message-ID: <1840eaff-b006-4512-8da3-f7c1463b8...@gmail.com>
>> Content-Type: text/plain;charset=us-ascii
>> 
>> Supposedly lowering Tx power on terrestrial network from +23 DBm to +9.8 DBm 
>> will make everything better.  Ajit Pai is listening only to carriers and 
>> ignoring DoD who is stating it will significantly degrade and/or make 
>> useless the GPS system.
>> 
>>  Not to mention ADS-B which was installed at great expense by the private 
>> and commercial aviation systems. And is totally dependent on the GPS 
>> segments most affected by Ligado
>> 
>> Read and weep
>> 
>> https://arstechnica.com/tech-policy/2020/04/fcc-to-approve-5g-network-despite-military-saying-it-will-harm-gps/

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Re: [time-nuts] LightSquared is back now called Ligado

[Scott McGrath]

That was +9.8 on the terrrestrial microcell transmitters,

Yes this seems to have been sold with the assurance that the magic brickwall 
filters with 100db/octave slope will be included in every one.

But the asian manufacturer of said devices will neglect to include them and 
juice the power a wee bit to say +23...

Of course this will hose every GPS system for miles around and for those of us 
who fly our multi thousand investment in ADS-B will be rendered useless as the 
ADS-B still uses L1.In our club’s Cessna 172 the new ADS-B in/out compliant 
radio stack was 20,000 as we are close to a lot of controlled airspace.


  I dropped a note to AOPA on this.   Because remember the entire airway system 
is now supposed to be managed by aircraft exchanging position, bearing altitude 
and rate of climb dynamically to each other and ground stations instead of 
todays radar based system.

And say goodbye to our GPSDO’s

On Apr 17, 2020, at 2:59 PM, Bob kb8tq  wrote:

Hi

Was that +9.8 or -98 dbm ? :)

At -98 they probably *could* coexist with GPS. Not real clear how well there
system would work at that level though. 

Bob

> On Apr 17, 2020, at 1:37 PM, Scott McGrath  wrote:
> 
> Supposedly lowering Tx power on terrestrial network from +23 DBm to +9.8 DBm 
> will make everything better.  Ajit Pai is listening only to carriers and 
> ignoring DoD who is stating it will significantly degrade and/or make useless 
> the GPS system.  
> 
> Not to mention ADS-B which was installed at great expense by the private and 
> commercial aviation systems. And is totally dependent on the GPS segments 
> most affected by Ligado
> 
> Read and weep
> 
> https://arstechnica.com/tech-policy/2020/04/fcc-to-approve-5g-network-despite-military-saying-it-will-harm-gps/
> 
> 
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[time-nuts] LightSquared is back now called Ligado

[Scott McGrath]

Supposedly lowering Tx power on terrestrial network from +23 DBm to +9.8 DBm 
will make everything better.  Ajit Pai is listening only to carriers and 
ignoring DoD who is stating it will significantly degrade and/or make useless 
the GPS system.  

 Not to mention ADS-B which was installed at great expense by the private and 
commercial aviation systems. And is totally dependent on the GPS segments most 
affected by Ligado

Read and weep

https://arstechnica.com/tech-policy/2020/04/fcc-to-approve-5g-network-despite-military-saying-it-will-harm-gps/


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Re: [time-nuts] eLoran

[Scott McGrath]

Lit up the Austron Monitor And the 117A looking forward to AOS

Content by Scott
Typos by Siri

> On Feb 10, 2020, at 9:56 AM, paul swed  wrote:
> 

Well good news on the old LORAN C receivers all are fine. Turned out I had
a single channel driver bad in the distribution amplifier. Simply used
another output. Preamp is good also.
Ready for next week and warming up the Cesiums for a check with a real
reference. Not that messy GPS stuff. Humor intended.
Regards
Paul
WB8TSL

> On Sat, Feb 8, 2020 at 5:55 PM paul swed  wrote:
> 
> That really is exciting. H hope the testing goes well.
> A comment. When ursanav was heavily testing 2013 region I had one of there
> stations here along with a HP5071 Cesium. They obtained data, I obtained
> serious fun.
> But what is very interesting is the LORAN antenna is no larger than some
> of the old GPS cone shape antennas.
> It was not fed with coax but 2 X twisted  shielded pair. The antenna was
> active. With two elements. The receiver was a 1RU box with a lot of space
> in it. All processing was done digitally. This solution along with the
> eLORAN signal could easily lock within cement and steel office buildings as
> tested and demonstrated. With todays ever more powerful processing the core
> might be the size of a cigarette pack as a guess.
> Back in the archives one of the Time-nuts had created a DSP LORAN
> receiver. Its fair to say that solution might be reused with the new signal.
> Regards
> Paul
> WB8TSL
> 
>> On Sat, Feb 8, 2020 at 4:20 PM Dave Hartzell  wrote:
>> 
>> Hi Bob-
>> 
>> Is the van still open to viewing?  I'm in Boulder as well, must be at
>> NIST?
>> 
>> Dave
>> 
>>> On Sat, Feb 8, 2020 at 2:07 PM Bob Martin  wrote:
>> 
>>> On Friday I was given a tour of a van that is
>>> being outfitted to monitor eLoran signals.
>>> Pretty exciting.
>>> 
>>> Bob
>>> Boulder,CO
>>> 
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Re: [time-nuts] eLORAN to turn on next week for a test

[Scott McGrath]

I hope we finally light up eLoran and soon not only is it needed for time 
transfer.   As a pilot there have been way too many GPS outages and the ADS-B 
peer to peer system is totally dependent upon precision positioning signals 
from GPS.

It’s unsettling to be doing a GPS approach only to be halfway into it and see 
‘GPS Signal Lost’ - system restart.   Now you need to go around and shoot an 
ILS approach or visual if conditions allow.

Of course most of the GPS outages are csused by truck drivers using GPS 
jammers.   But the why actually makes no difference GPS is gone and you are on 
your own.

> 
> On Feb 7, 2020, at 5:57 PM, paul swed  wrote:
> 

Hello fellow time-nuts. Just found out eLORAN will be on next week or so.
Bringing Wildwood back on air the week of February 17th and then again the
week of March 16th for a demonstration of UTC time synchronization. We’ll
be broadcasting as 8970M and 8970X from Wildwood during those times.
So if you still have gear and want to warm it up for checking frequency
here is your chance.
I already know I need to replace a 20' section of a 164' line of RG6 from a
squirrel attack. Just replaced 140' of a 174' line due to the same for WWVB.
Fortunately thats quite easy to do. Wonder if the pre-amps still good?
Regards
Paul
WB8TSL
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Re: [time-nuts] Cesium Mechanical Chronometer

[Scott McGrath]

Remember you ‘beat’ a clock using a audio amplifier and a standard signal there 
is a screw which adjusts the tension on the escapement spring,   Now you could 
use a reduction drive to turn the screw or take direct control of the 
escapement spring using the mechanical ‘ticks’ of the escapement as the input 
to a control loop

Content by Scott
Typos by Siri

> On Jan 30, 2020, at 7:05 PM, Tom Van Baak  wrote:
> 

That would be a fun project. There are examples of measuring a M21 on Bryan's 
site:

https://www.bmumford.com/mset/tech/chrono/

Here are phase and ADEV plots for my M21:

http://leapsecond.com/pages/m21/

That page also shows you a typical chronometer rate card, which provides the 
key "paper clock" advantage over using the clock dial alone.

I use a piezo pickup to extract timing pulses from the clock. The audio 
waveform isn't pretty but you can form a low jitter 1PPS out of it. Laser 
sensors give a cleaner signal but are more difficult to use with an M21.

Running a GPS/CSAC + M21 in a master/slave arrangement should be easy, although 
I don't know how you'll handle the rate card corrections.

Running them in phase lock will be much harder. You can probably discipline the 
CSAC from the M21 using RS232 commands to the CSAC. But to discipline the M21 
from the CSAC requires that you have a way to dynamically adjust the rate of 
the M21 at ppm levels. That's going to be tricky, given that high-end 
compensated chronometers like this are specifically designed to be as immune to 
internal and external changes as possible. One avenue may be the winding 
interval: notice the slopes of the phase plot.

The biggest problem I had with long-term data collection was re-winding the 
chronometer. If you design a non-invasive auto-winder as part of your project, 
please contact me.

/tvb


On 1/30/2020 7:49 AM, Tom Bales wrote:
>> And now for something completely different:  I am working on a quixotic
>> project to control a standard, detent-escapement marine chronometer (e.g.,
>> Hamilton 21) with a CSAC cesium atomic clock module.  Yes, I know this
>> makes no sense--but, then, we're timenuts.  I want the mechanical
>> chronometer to function normally if the CSAC signal, presumably a 1pps
>> pulse, is lost.  The CSAC will be GPS disciplined, so during normal
>> operation, with an operating GPS constellation, the time is referenced to
>> UTC via GPS; if GPS is lost, then the CSAC takes over and its 1pps signal
>> drives the chronometer; if all electronics are lost, the chronometer hangs
>> in as a mechanical chronometer.  Has anyone any experience with
>> electrically controlling (or disciplining) a marine chronometer?
>> 
>> 
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Re: [time-nuts] USB over optical fiber

[Scott McGrath]

Wow,  cost cutting at work I have the corning one but its 3 years old Remember 
when FCC certification meant something for EMC 





> On Dec 6, 2019, at 3:21 PM, David Van Horn 
>  wrote:
> 

Well, it arrived, and it is NOISY.  ☹
It's pushing out longitudinal noise along the cable, and it's deafening my 
receiver.

After doing some research this morning, it appears that they do the DATA 
optically but power is taken on copper wires, and I'm betting a boost switcher 
to compensate for the voltage drop in the 28 ga wire.

https://www.corning.com/microsites/coc/ocbc/Documents/CNT-075-AEN.pdf



I have another candidate arriving today which will require a 5V supply inside 
the cage, but I can do that with batteries and a linear regulator, much quieter.


--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: david.vanh...@backcountryaccess.com 

-Original Message-
From: time-nuts  On Behalf Of David Van Horn 
via time-nuts
Sent: Thursday, December 5, 2019 6:15 AM
To: Scott McGrath ; Discussion of precise time and 
frequency measurement 
Cc: David Van Horn 
Subject: Re: [time-nuts] USB over optical fiber

Ok, thanks for the info.  My unit should be arriving today or tomorrow.

--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: david.vanh...@backcountryaccess.com 

-Original Message-----
From: Scott McGrath 
Sent: Wednesday, December 4, 2019 9:16 PM
To: Discussion of precise time and frequency measurement 

Cc: David Van Horn 
Subject: Re: [time-nuts] USB over optical fiber

You may still have a problem,  That said most of your noise power is going to 
come from your USB device itself and perhaps the power supply 

That said ive never really had a problem doing similar testing using small 
chambers from ETS-Lindgren and similar vendors using the Corning interface. 

That said i’d recommend you go a step up to the Newnex and similar devices they 
are 3x the price but the fiber interlink is just a standard fiber LC-LC patch 
cord.

With the low cost interface crimp its cable once accidentally you are buying a 
new one.

With the newnex you are buying a 20-30 dollar patch cord.

All that said performance is the same in the end but the newnex and similar 
have an advantage in an open lab.   For permanent installation in raceway the 
cost advantage is with the one piece units.

Content by Scott
Typos by Siri

> On Dec 4, 2019, at 10:07 PM, Davida  Van Horn via time-nuts 
>  wrote:
> 

I'm not too worried up there, my receivers are working at 457 kHz. 

-Original Message-
From: Scott McGrath 
Sent: Wednesday, December 4, 2019 12:14 AM
To: Discussion of precise time and frequency measurement 

Cc: David Van Horn 
Subject: Re: [time-nuts] USB over optical fiber

Its not so much the noise from the interface its the USB device itself i’d 
worry about as USB 3.0 generates RF signals up to 3 GHz.   And also has fairly 
strong signals in the 2.4 GHz ISM band.

Content by Scott
Typos by Siri

> On Dec 4, 2019, at 12:07 AM, David Van Horn via time-nuts 
>  wrote:
> 

I suppose this is vaguely time-nutty. 

I have an application where I need to take USB into an EMC faraday cage.
I see a number of optical fiber implementations available, and the prices 
($200-300) are acceptable, but I’m worried about noise that the downstream end 
may cause, since it will need to be inside the cage.

Does anyone have experience with these?  Ones to stay away from?



--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: 
david.vanh...@backcountryaccess.com<mailto:david.vanh...@backcountryaccess.com>

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Re: [time-nuts] USB over optical fiber

[Scott McGrath]

You may still have a problem,  That said most of your noise power is going to 
come from your USB device itself and perhaps the power supply 

That said ive never really had a problem doing similar testing using small 
chambers from ETS-Lindgren and similar vendors using the Corning interface. 

That said i’d recommend you go a step up to the Newnex and similar devices they 
are 3x the price but the fiber interlink is just a standard fiber LC-LC patch 
cord.

With the low cost interface crimp its cable once accidentally you are buying a 
new one.

With the newnex you are buying a 20-30 dollar patch cord.

All that said performance is the same in the end but the newnex and similar 
have an advantage in an open lab.   For permanent installation in raceway the 
cost advantage is with the one piece units.

Content by Scott
Typos by Siri

> On Dec 4, 2019, at 10:07 PM, Davida  Van Horn via time-nuts 
>  wrote:
> 

I'm not too worried up there, my receivers are working at 457 kHz. 

-Original Message-----
From: Scott McGrath  
Sent: Wednesday, December 4, 2019 12:14 AM
To: Discussion of precise time and frequency measurement 

Cc: David Van Horn 
Subject: Re: [time-nuts] USB over optical fiber

Its not so much the noise from the interface its the USB device itself i’d 
worry about as USB 3.0 generates RF signals up to 3 GHz.   And also has fairly 
strong signals in the 2.4 GHz ISM band.

Content by Scott
Typos by Siri

> On Dec 4, 2019, at 12:07 AM, David Van Horn via time-nuts 
>  wrote:
> 

I suppose this is vaguely time-nutty. 

I have an application where I need to take USB into an EMC faraday cage.
I see a number of optical fiber implementations available, and the prices 
($200-300) are acceptable, but I’m worried about noise that the downstream end 
may cause, since it will need to be inside the cage.

Does anyone have experience with these?  Ones to stay away from?



--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: 
david.vanh...@backcountryaccess.com<mailto:david.vanh...@backcountryaccess.com>

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Re: [time-nuts] USB over optical fiber

[Scott McGrath]

Its not so much the noise from the interface its the USB device itself i’d 
worry about as USB 3.0 generates RF signals up to 3 GHz.   And also has fairly 
strong signals in the 2.4 GHz ISM band.

Content by Scott
Typos by Siri

> On Dec 4, 2019, at 12:07 AM, David Van Horn via time-nuts 
>  wrote:
> 

I suppose this is vaguely time-nutty. 

I have an application where I need to take USB into an EMC faraday cage.
I see a number of optical fiber implementations available, and the prices 
($200-300) are acceptable, but I’m worried about noise that the downstream end 
may cause, since it will need to be inside the cage.

Does anyone have experience with these?  Ones to stay away from?



--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO  80301 USA
phone: 303-417-1345  x110
email: 
david.vanh...@backcountryaccess.com

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Re: [time-nuts] Dead 5061B

[Scott McGrath]

Have you checked the HV supplies?

Content by Scott
Typos by Siri

> On Nov 3, 2019, at 2:04 PM, AC0XU (Jim)  wrote:
> 

Time Nuts-

This 5061B was working fine until a recent power failure, after which the unit 
would not come on line (alarm light stayed lit).

Major symptoms now: 

Beam I  ; Second Harmonic;  Ion Pump Supply are all 0 on front panel.  All 
other front panel readings are normal. (except for battery, which th unit doe 
snot have).

L4P2 signal is 16.832 MHz 1.7 V p-p  (perfect - suggesting that A1 synthesizer 
is fine)

Going through 5-173 A12 Cesium Beam Tube Operational Checks:

5-175 Low Frequency Coil Check. Everything is fine except that tweaking the 
external oscillator frequence/amplitude has no effect. Beam I is always 0.

The text says "If the beam current is not restored, it indicates a problem in 
the the cesium beam tube power supplies (A11, A15, A18, or A19) or in the 
cesium beam tube itself.

A11 = Cesium Oven Controller - front panel reading is fine. Removed A11 from 
the chassis and made the tests in  5-141.
Everything fine. +- 16V and -10V all fine; Cs oven voltage fine; the thermistor 
tests out at 435 ohm vs. the 430 ohm on the label.

A15 = Power Regulator Board - main +18.65V is fine

A18 = +3.5KV supply - measured and is fine

A19 = -2.5KV supply - measured and is fine

I am inclined to conclude that the tube is dead. I don't understand why that 
occurred suddenly in conjunction with a line power failure.

Can I have any hope that the tube is still o.k.?  Any ideas?

Thanks!

Jim


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Re: [time-nuts] DC distribution

[Scott McGrath]

4 pin xlr is also standard for pro audio/video. So you might want to use the 
same pin configuration as the ‘standard’ so you can use the large variety of 
accessories available.

Content by Scott
Typos by Siri

On Oct 22, 2019, at 7:42 PM, "n...@lazygranch.com"  wrote:

Glad I read all the replies since I was also going to suggest Canon
connectors. I have used the 3 pin canon because they are easy to find
and I am not going to plug a microphone into a power supply. The
breakout box is unique enough to not get it confused with anything
else. (Not suitable for the general public!!!)

That said, the 4 pin canon is a good idea. It is a power supply
standard. You can find cables online.  

Mine is designed for battery use. I put reverse biased diodes across
the supply and use a fuse. I never hooked it up backwards but you never
know.

If you need to make holes for the Canon jacks, those Harbor Freight
multi-hole drills work fine.  

On Fri, 4 Oct 2019 13:32:12 +0100
"Paul Bicknell"  wrote:

> Hi I am standardising on 4 pin XLR connectors for 12 Volts as used in
> the TV industry Perhaps you could use the 6 pin for 5 volts 
> I do not recommend the 2 pin as this is for 240 V ac 
> Or the 3 pin as you could take out a microphone 
> 
> I am going to be Using military connectors for 24 V DC and 400 Hz
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf
> Of John Ackermann. N8UR
> Sent: 04 October 2019 12:40
> To: David Van Horn via time-nuts
> Subject: Re: [time-nuts] DC distribution
> 
> I use lots and lots of Anderson PowerPoles and (mostly) West Mountain
> Radio distribution units.  I have different color codes for different
> voltages -- red/black for 12v, orange/black for 24v, green/black for
> 5v, etc.  Primary 12 and 24 volt sources are big AGM batteries across
> float chargers.
> 
> On Oct 4, 2019, 2:03 AM, at 2:03 AM, Bill Dailey 
> wrote:
>> Setting up a new workbench and am wondering what wisdom people can
>> offer.  I am powering numerous synthesizers (5v), small receivers
>> (5v), Upconverters (5v), larger receivers (12v), fury Gpsdo’s..
>> etc.   anyone use something neat and not real expensive for
>> distributing 5v and 12v. I am hoping for a long COTS pcb with fusing
>> and maybe holes for plugs. 
>> 
>> 
>> Any insights?
>> 
>> Bill
>> 
>> Bill Dailey
>> 
>> Negativity always wins the short game. But positivity wins the long
>> game. - Gary Vaynerchuk
>> 
>> Don’t be easy to understand, 
>> Be impossible to misunderstand 
>> - Steve Sims
>> ___
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> 
> -
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2016.0.8048 / Virus Database: 4793/15886 - Release Date:
> 08/14/18 Internal Virus Database is out of date.
> 
> 
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Re: [time-nuts] HP105B HP 105B 1 amp fuse blowing

[Scott McGrath]

As one who owns a 105 i had the battery properly rebuilt and basically have it 
on low rate charge and periodically discharge the battery

When rebuilding a 105 battery it’s important to replicate its characteristics 

Remember HP also intended I believe that the battery would also serve as a 
filter for the power supply.   As I dont recall any version of the 105 without 
a battery.



On Oct 10, 2019, at 4:50 PM, Taka Kamiya via time-nuts 
 wrote:

The fact that 25V supply is dropping to 23.4V shows it is drawing far more 
current than it is rated.  I am assuming this is a regulated power supply.  
Does the power brick actually shuts down at 500mA or does it let the the 
voltage drop and try to supply what it can?  Maybe one or more Nicad has an 
internal short?  That will cause and over-voltage situation per battery and 
thus over-current.  I've recently seen a brick power supply go into oscillation 
and produce 3x rated voltage when too much current was drawn.  (and blew the 
circuit)

Also, different batteries has different charging rates.  As far as 105B 
document goes, it says 24V 0.5Amp supply but that is for default configuration. 
Designed charge rate is 390mA (page 3-4) and is current controlled by A5Q3.

I would actually measure how much current is drawn there.  Since the fuse is 
already blown, just put an am-meter across the fuse and see  

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG


   On Thursday, October 10, 2019, 4:00:41 PM EDT, Roy Thistle 
 wrote:  

Hi All:
A 105B (quartz oscillator) is blowing the 1A fuse, after it is on about 1 hour.
The fuse appears to have just melted (not a black mark as the result of a 
flash, in the case of a high current short.)… just looks like the fuse wire 
(inside the glass capsule) melted into some little blobs, for about 1/4  the 
fuse length, near the middle. It wasn't a fast-blo or slow-blo fuse... just the 
normal kind.
I think the unit is drawing just a little too much current, as the result of 
the batteries needing charging (I had the fast charge option on when the fuse 
blew.) And so, the fuse heated up, and finally melted. Not sure why the 
batteries were not charging normally... but 20.1 volts is what I measured 
across the pack, initially, and 23.4 V after about 45 min of charging.
I am charging the batters, from a power cube, at 510 ma, and dropping (cube 
gives 25V, 500mA max)… the batteries are 20 C size NiCads, wired in series... 
that of course is a retrofit.
I don't want to put another fuse in, and blow that too, without some reasonable 
explanation of why the first one failed!
Please, any comments, or hints/suggestions... much appreciated.
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Re: [time-nuts] DC distribution

[Scott McGrath]

I have a similar crimper for lugs it works nicely,  the cross section is the 
proof of the pudding so to speak.

Content by Scott
Typos by Siri

On Oct 8, 2019, at 12:14 AM, Mark Goldberg  wrote:

At a risk of having you folks tear it apart, here is my poor man's guide to
getting good crimps on large cables:

https://sites.google.com/site/marksrvmods/home/battery-wiring

You can see the cross section and there are no voids at all. You can hardly
see where the wire strands end and the lug begins.

These have given up to two years of service in my RV with no issues. I do
similar crimps with the Anderson SB175s.

I am using welding cable with a lot of strands. Tinned Marine cables and
lugs would be even better, but we live in a very dry climate.

Regards,

Mark
W7MLG


On Mon, Oct 7, 2019 at 9:00 PM Martin Flynn 
wrote:

> After a failure under load of a starter cable on a large generator, I
> finally broke down and bought a Burndy hydraulic crimper for the grounds
> and cables I normally use.
> 
> Did two test low-tech tests:
> 
> First test on a 1" section of 2/0 DLO cable, with a two bolt telco lug
> at each end.  It failed at ~2200 ft/lbs, the wire itself broke strand by
> strand.
> 
> Second test involved sawing the crimp across the barrel and looking for
> voids.  Using factory lugs and die, no voids were visible at 25X
> magnification
> 
> 
> 
>> On 10/6/2019 2:46 PM, Mark Goldberg wrote:
>> It is even more difficult. I bought some cables from a company because I
>> did not have a crimper for 4/0. I was not impressed. My crimps were much
>> better.
>> 
>> I don't have a specific recommendation, but you should get a feel from
> them
>> that they understand the standards. Places that do work for aviation
>> generally have to do good work, as lives depend on it. Unfortunately, it
> is
>> a high labor activity, so many are not in the US. A long time ago, I
> worked
>> with some just south of the border in Mexico that did good work.
>> 
>> Regards,
>> 
>> Mark
>> W7MLG
>> 
> 
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Re: [time-nuts] DC distribution

[Scott McGrath]

As to crimping tools it’s important to use the correct power pole tooling as 
the alignment of the crimp is critical to contact insertion.   

Ive found the West Mountain Radio tool to be good for the smaller powerpoles  
I’ve got the Anderson crimper for the 75 amp powerpoles.

Anything larger - i use a local assembly house which has hydraulic crimpers for 
Anderson connectors.



On Oct 5, 2019, at 7:24 AM, Adrian Godwin  wrote:

I used powerpoles on a project and tried to use a crimping tool I had to
hand. Amphenol, I think. It appeared to be the right size but ended up
bending the terminal badly where it changes from circular to flat. The
results were unreliable and I ended up soldering (though adding sleeving,
which together with the natural bend-restriction on the shell has mostly
avoided stiffening the wire where it's most vulnerable).

I know some crimp terminal are very fussy about the tool used but it's
usually the miniature ones like JST. Does the powerpole terminal need a
powerpole-specific crimp tool ? I note that the West Mountain tool seems to
be branded by themselves rather than Anderson, but I can't tell if it's
generic or made to their specs.

> On Sat, Oct 5, 2019 at 2:00 AM John Ackermann N8UR  wrote:
> 
> Not a perfect solution, but for semi-permanent connections you can run a
> small tie-wrap lengthwise so the ends pass through the space between where
> the wires on each end split and the body.  Cinch it tight and the
> connectors won't come apart without cutting the tie wrap.
> 
> On Oct 4, 2019, 7:04 PM, at 7:04 PM, Taka Kamiya via time-nuts <
> time-nuts@lists.febo.com> wrote:
>> I used to use power pole, too but they don't lock firmly enough for my
>> liking.  So I don't use them anymore.  It would be perfect if there is
>> an option to add positive locking mechanism of some kind.
>> 
>> ---
>> (Mr.) Taka Kamiya
>> KB4EMF / ex JF2DKG
>> 
>> 
>> On Friday, October 4, 2019, 4:06:50 PM EDT, Didier Juges
>>  wrote:
>> 
>> That's what I do too. I do use Power Pole for my ham stuff that draws
>> high
>> current but for all the <2A 12V stuff the 5.1mm barrel connector with
>> positive center is hard to beat because I have so many power sources
>> and
>> equipment already wired for it. I am not ready to rewire all the off
>> the
>> shelf equipment that came with one of those.
>> 
>> Power Pole are convenient for batteries though because you can use the
>> connector to charge the battery or use it as a source.
>> 
>> Didier KO4BB
>> 
>> On Fri, Oct 4, 2019, 2:01 PM Taka Kamiya via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>> 
>>> Mine is very simple
>>> USB connector for 5VBarrel connector 5.5/2.1mm for 12VTerminal strip
>> for
>>> 24V
>>> None of them are high power devices.
>>> 
>>> ---
>>> (Mr.) Taka Kamiya
>>> KB4EMF / ex JF2DKG
>>> 
>>> 
>>>   On Friday, October 4, 2019, 2:03:55 AM EDT, Bill Dailey <
>>> docdai...@gmail.com> wrote:
>>> 
>>> Setting up a new workbench and am wondering what wisdom people can
>>> offer.  I am powering numerous synthesizers (5v), small receivers
>> (5v),
>>> Upconverters (5v), larger receivers (12v), fury Gpsdo’s.. etc.
>> anyone use
>>> something neat and not real expensive for distributing 5v and 12v.  I
>> am
>>> hoping for a long COTS pcb with fusing and maybe holes for plugs.
>>> 
>>> Any insights?
>>> 
>>> Bill
>>> 
>>> Bill Dailey
>>> 
>>> Negativity always wins the short game. But positivity wins the long
>> game.
>>> - Gary Vaynerchuk
>>> 
>>> Don’t be easy to understand,
>>> Be impossible to misunderstand
>>> - Steve Sims
>>> ___
>>> 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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Re: [time-nuts] DC distribution

[Scott McGrath]

+1 for powerpole connectors and purchasing a proper ratcheting crimper for the 
powerpoles.   AND being willing to discard marginal crimps.

 

Content by Scott
Typos by Siri

On Oct 4, 2019, at 5:38 PM, Bill Dailey  wrote:

There are locks you can get.  I saw them on Mountain West today.

Bill Dailey

Negativity always wins the short game. But positivity wins the long game. - 
Gary Vaynerchuk

Don’t be easy to understand, 
Be impossible to misunderstand 
- Steve Sims

> On Oct 4, 2019, at 6:04 PM, Taka Kamiya via time-nuts 
>  wrote:
> 
> I used to use power pole, too but they don't lock firmly enough for my 
> liking.  So I don't use them anymore.  It would be perfect if there is an 
> option to add positive locking mechanism of some kind.
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> 
> 
>   On Friday, October 4, 2019, 4:06:50 PM EDT, Didier Juges 
>  wrote:  
> 
> That's what I do too. I do use Power Pole for my ham stuff that draws high
> current but for all the <2A 12V stuff the 5.1mm barrel connector with
> positive center is hard to beat because I have so many power sources and
> equipment already wired for it. I am not ready to rewire all the off the
> shelf equipment that came with one of those.
> 
> Power Pole are convenient for batteries though because you can use the
> connector to charge the battery or use it as a source.
> 
> Didier KO4BB
> 
>> On Fri, Oct 4, 2019, 2:01 PM Taka Kamiya via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>> 
>> Mine is very simple
>> USB connector for 5VBarrel connector 5.5/2.1mm for 12VTerminal strip for
>> 24V
>> None of them are high power devices.
>> 
>> ---
>> (Mr.) Taka Kamiya
>> KB4EMF / ex JF2DKG
>> 
>> 
>>On Friday, October 4, 2019, 2:03:55 AM EDT, Bill Dailey <
>> docdai...@gmail.com> wrote:
>> 
>>  Setting up a new workbench and am wondering what wisdom people can
>> offer.  I am powering numerous synthesizers (5v), small receivers (5v),
>> Upconverters (5v), larger receivers (12v), fury Gpsdo’s.. etc.  anyone use
>> something neat and not real expensive for distributing 5v and 12v.  I am
>> hoping for a long COTS pcb with fusing and maybe holes for plugs.
>> 
>> Any insights?
>> 
>> Bill
>> 
>> Bill Dailey
>> 
>> Negativity always wins the short game. But positivity wins the long game.
>> - Gary Vaynerchuk
>> 
>> Don’t be easy to understand,
>> Be impossible to misunderstand
>> - Steve Sims
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com
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Re: [time-nuts] Truetime XL / XLi question

[Scott McGrath]

Ive got one as well,  i’ll look at it over the weekend but as I recall these 
are all string outputs which require parsing.  The problem with fault and alarm 
is without manual dont have a list of possible faults and alarms

Version is easy its the same as displayed on LCD

Content by Scott
Typos by Siri

On May 23, 2019, at 11:09 AM, linc...@ampmonkeys.com wrote:

> On 2019-05-16 20:13, Mark Sims wrote:
> I am in the process of adding Truetime XL (DC and AK) support to Lady
> Heather.  It looks like I can also support the XLi (does NTP), but the
> XLi manual has some vague/conflicting info for the output of these
> commands:
> F18 - version
> F72 - faults
> F73 - alarms
> Does anybody have an XLi and can capture the serial port output
> response to these commands?
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We have one in the lab. I will see whats up.

Link

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Re: [time-nuts] Bombe clock

[Scott McGrath]

You and the builder of this clock win the internet today!

Content by Scott
Typos by Siri

On May 21, 2019, at 1:54 PM, Mark Sims  wrote:

Everbody needs one of these...

https://www.ebay.co.uk/itm/The-Covert-Bombe-Clock-from-Bad-Dog-Designs-Codebreaking-in-Secret/123775434764

https://www.youtube.com/watch?v=O4ctUqgj7aY
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Re: [time-nuts] multimeter

[Scott McGrath]

I’d go with the old standard the Fluke 87 lifetime warranty,  true RMS AC 
measurements,  rugged and 4-1/2 digits

Content by Scott
Typos by Siri

On Mar 23, 2019, at 8:05 AM, Jim Palfreyman  wrote:

Hi all,

I think I'm in the market for a new digital multimeter.

Could I have some recommendations?

Jim
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Re: [time-nuts] Portable Time Standard - Additional Clarification

[Scott McGrath]

Mechanical chonometers are still rated and the offset applied.  This was 
probably the earliest application of the offset with respect to the time 
standards of the day.  I.e. Greenwich and USNO among others.



Content by Scott
Typos by Siri

On Jan 12, 2019, at 5:15 PM, Jim Harman  wrote:

I don't have modern knowledge of this, but traditionally marine
chronometers were not adjusted for precise timekeeping, but rather would be
"rated" for how much they would gain or lose per day and that correction
would be applied at the time of the astronomical observation.

Do you have an opportunity to post-process your data, i.e. record the
offset of your standard periodically so that you can interpolate the
results? That would probably make the requirements a lot less demanding.

> On Sat, Jan 12, 2019 at 4:28 PM Joe Hobart  wrote:
> 
> Here is more explanation:
> 
> I need a stand-alone, easily portable unit with display; the unit may be
> used
> where GPS, cell phone, or WWVB are not available.  Low power consumption is
> highly desirable.
> 
> I have seen advertisements of marine quartz chronometers listing an
> accuracy as
> good as <0.01 second/day at a constant temperature of 22 C.  Has anyone had
> experience with a marine quartz chronometers?  If so, how much did the
> accuracy
> vary with temperature?
> 
> 
> Thanks for the suggestions about pickup coils;  I had hoped a coil would
> detect
> the clock movement well enough to compare to a standard 1 PPS.  I have a
> Motorola GPS timing module and a storage oscilloscope for comparison.
> 
> Joe
> 
> ---
> This email has been checked for viruses by AVG.
> https://www.avg.com
> 
> 
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-- 

--Jim Harman
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Re: [time-nuts] Need recommendation for GPS antenna for Oncore GPS module

[Scott McGrath]

For timing use ideally it should be above the roofline by at least several feet 
otherwise satellites close to the horizon will be not be visible.

The generally preferred antenna is the Agilent/Keysight/Symmetricom. 58504A 
antenna also any outdoor antenna made by Trimble or TrueTime as long as antenna 
does not use a downconverter.



On Nov 3, 2018, at 5:26 PM, Toby Riddell  wrote:

Hi all,

I want to fit a GPS antenna on our house (the attic is being renovated and
it just occurred to me that if I move fast I can get it done before the
walls are closed up again!)

I was planning on having it mounted on a south-facing wall but below the
roofline - does this sound okay for picking up satellites? It can poke
above the roofline if needed as long as the mounts are on the wall (not the
top of the roof).

Is there a recommended antenna? I am planning on feeding it into an Oncore
GPS module which will then interface to a Soekris net4501 running nanoBSD
and ntpns.

Thanks!

Toby
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Re: [time-nuts] Racal Dana 9478 frequency distribution system with option 04B high stability oven (5x10^-10/day aging rate).

[Scott McGrath]

Racal overall has a reputation for making very high quality instruments,   
Since the OCXO is an option,and the price is right on the DA,   I’d 
probably buy it.

Also thinking since its an option the OCXO can probably be switched out of 
circuit or removed entirely.

Im guessing Racal thought that adding an OCXO would be a feature for shops that 
did not have a frequency standard and/or one that used a different frequency 
than ‘standard’ like a TV station.   So everything would be phase locked to a 
master clock irrespective of frequency.



Content by Scott
Typos by Siri

On Nov 4, 2018, at 6:50 AM, David C. Partridge  
wrote:

FWIW it is trivial to modify these video distribution amps for 50 ohm output - 
you just need to change the output resistors form 75 ohm to 50 ohm on the board 
after the op-amp.

David

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Dr. 
David Kirkby
Sent: 04 November 2018 10:44
To: time-nuts@lists.febo.com
Subject: [time-nuts] Racal Dana 9478 frequency distribution system with option 
04B high stability oven (5x10^-10/day aging rate).

I want a distribution amplifier to distribute 10 MHz from an HP GPS
:
Currently I am using 75 ohm video amplifiers, but I suspect that is sub
optimal.


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Re: [time-nuts] GPIB interfaces these days

[Scott McGrath]

I use NI USB interfaces,  They are reliable process ATN messages and of course 
have the vast programming library associated with NI interfaces.

Used ones can be found on the well known auction site for 250-400 bucks.
Make sure you get the BLUE ONES the Brown ones are USB 1.0 and are obsolete.

As to your older Prologix interfaces they SHOULD still work just fine,  i dont 
think much has changed with them over the years other than packaging.   Get the 
driver  and give them a shot.



On Nov 2, 2018, at 7:39 AM, Adrian Godwin  wrote:

How important is ATN in a typical time-nuts usage ?

I can see it being important in a complex ATE setup where some instruments
are automatically providing data to a schedule and need to be serviced, but
in my understanding the time-nuts case is often capturing a stream of data
from a single TIC. Are there other common configurations that need ATN
handling ?

Although GPIB is (obviously) a bus, it seems to me that modern usage could
be handled more easily using multiple USB interfaces, each connected to
only one instrument. This means the interface can be much cheaper than an
82357a or similar, because it doesn't need bus buffers capable of driving a
full load, and you can use lightweight USB cabling instead of the heavy
GPIB cable.

Getting further off-topic (so please followup off-list if this is of
interest), I'm surprised that the 82357a appears to contain both an FPGA
and a cypress FX2 USB device. The cypress device has a crude (8051)
processor but also a programmable DMA engine that ought to be capable of
doing the source-acceptor handshake on its own. Why does the HP interface
need the FPGA too ?

You can buy FX2 dev boards (sold to be used as clones of Salae and other
USB logic analysers) for a few pounds each. Of course, this doesn't allow
instrument-to-instrument transfers but this is probably mitigated by having
a fast PC and multiple busses - a star rather than a bus topology.



On Fri, Nov 2, 2018 at 9:43 AM Forrest Christian (List Account) <
li...@packetflux.com> wrote:

> I use a national instruments PCI-GPIB card in a Windows 10 PC, works just
> fine.   Usually can find them <$100 on eBay.
> 
> I've also used a HP/Agilent 82357A (or B) which does USB-GPIB for those
> cases when you need it for a laptop or something else without a pci or pcie
> slot.
> 
> I understand the USB ones in particular are prone to being counterfeited,
> but evidently most of the counterfeit ones work even though they're not
> original HP/Agilent.
> 
> There are various other options out there, for instance prologix (and
> possibly others) make a GPIB-ETHERNET converter which will convert GPIB
> instruments to network instruments.
> 
> 
> 
>> On Fri, Nov 2, 2018 at 2:05 AM Rex  wrote:
>> 
>> So I've got some test equipment devices (mostly HP) with GPIB (or
>> actually HPIB) connectors. Also a few others as non-HP stuff.
>> 
>> Mostly I have talked to them with a NI GPIB card in a PCMCIA slot in a
>> laptop. Works great but the small notebook PC I have with a PCMIA slot
>> is from the early 2000's and I'm worrying what if it dies. It is running
>> XP but usually not on the internet.
>> 
>> I also have a couple very early aluminum case Prologix USB interfaces
>> that I haven't tried to use in 10 years. I think I remember hearing
>> these early ones had some issues, and I'd have to dig to re-learn how to
>> talk to them.
>> 
>> So I haven't looked at GPIB interface devices in a long time but I'm
>> getting a bit paranoid about the good NI PCMCIA card in a very old PC.
>> 
>> I don't remember seeing much discussion about this lately.
>> 
>> Is there anything new I should look at. I would have thought there might
>> be something with Arduino or maybe Ras Pi by now, possibly needing some
>> interfacing hardware, but I'm not aware of anything.
>> 
>> So, any advice from the group?  Old or new. Are my very old Prologix
>> interfaces still worth looking at?
>> 
>> -Rex
>> 
>> 
>> 
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> 
> 
> --
> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602
> forre...@imach.com | http://www.packetflux.com
>   
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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

My company paid for my shield room the real trick was getting the door in which 
weighed 600-800 pounds.

As to the old generator I restore old machinery as another hobby for the times 
I want to disengage brain.   But photoetched brass id plates show so much more 
thought than thermal printed labels

Content by Scott
Typos by Siri

On Sep 8, 2018, at 9:48 PM, William H. Fite  wrote:

We sound like we could be cousins, Scott. When we bought our current house,
I discovered that the previous owner had built a Faraday cage in a small
room off the basement. I put all my stuff in there. I also have a generator
with magneto ignition so I should be good to go when the end-of-the-world
arrives.



> On Saturday, September 8, 2018, Scott McGrath  wrote:
> 
> Actually
> 
> I do have much of my equipment inside a shield room,  not for tinfoil hat
> reasons but to keep experimental systems from causing interference and to
> eliminate existing RF sources in the 800 Mhz to 8 Ghz range as error
> sources in measurements.
> 
> If one is concerned there are lots of old screen rooms coming up for sale
> on e-bay as WiFi manufacturers prepare to dip their toes into bands above
> 10 Ghz and many of the old ones were only good to 6-8 Ghz.
> 
> As to backup generators I have a modern one and an ‘old school’
> mechanically governed one with magneto ignition.I keep that one mainly
> because i like its Art Deco design.Sometimes bring it to local Ag Fair
> to display among the gear from that era.
> 
> Content by Scott
> Typos by Siri
> 
> On Sep 8, 2018, at 8:11 PM, William H. Fite  wrote:
> 
> 
> 
> Gentlemen, I've found this discussion interesting and informative. This
> household works on quantum information theory rather than engineering so
> there is much for us to learn.
> 
> I must observe that if an event takes out the entire GPS system (which a
> Carrington event would not do) we will have issues a great deal more
> immediate and pressing than getting hyper-precise timing systems restored.
> 
> And speaking of Carrington events, how many of us have our equipment
> surrounded by Faraday cages and supplied with off-grid power? Because
> without those, we won't have instruments to measure T at home or even in
> a great many labs and businesses.
> 
> Just a thought.
> 
> 
> 
> 
>> On Saturday, September 8, 2018, Dana Whitlow 
> wrote:
>> 
>> I argue that when the "big one" happens, getting back to where we are
>> technologically
>> will be in large part a bootstrapping kind of affair.  And I believe that
>> starting off with
>> WWV* will be a far better starting point than starting with sun clocks
> and
>> dripping
>> water.
>> 
>> Dana
>> 
>> 
>> On Sat, Sep 8, 2018 at 5:54 PM, Ruslan Nabioullin > 
>> wrote:
>> 
>>>> On Fri, Sep 7, 2018 at 8:32 PM Bob kb8tq  wrote:
>>>> 
>>>> This is Time Nuts, not end of the world nuts …..
>>>> ...
>>>> I think we’ve all heard plenty of “the world is ending” stuff.
>>>> 
>>> 
>>> But the availability of a T service under adverse conditions and the
>>> ability of a system which consumes a T reference to gracefully degrade
>>> its functionality upon degradation or absence of reference input(s) are
>>> features/figures of merit---I do not see how discussion of that aspect
>> can
>>> be considered to be offtopic.
>>> 
>>> -Ruslan
>>> 
>>> --
>>> Ruslan Nabioullin
>>> Wittgenstein Laboratories
>>> rnabioul...@gmail.com
>>> (508) 523-8535
>>> 50 Louise Dr.
>>> Hollis, NH 03049
>>> ___
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>>> and follow the instructions there.
>>> 
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> 
> 
> --
> Patriotism is supporting your country all the time, and your government
> when it deserves it.
> --Mark Twain
> 
> We may be surprised at the people we find in heaven. God has a soft spot
> for sinners. His standards are quite low.
> --Desmond Tutu
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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

Actually 

I do have much of my equipment inside a shield room,  not for tinfoil hat 
reasons but to keep experimental systems from causing interference and to 
eliminate existing RF sources in the 800 Mhz to 8 Ghz range as error sources in 
measurements.

If one is concerned there are lots of old screen rooms coming up for sale on 
e-bay as WiFi manufacturers prepare to dip their toes into bands above 10 Ghz 
and many of the old ones were only good to 6-8 Ghz.  

As to backup generators I have a modern one and an ‘old school’ mechanically 
governed one with magneto ignition.I keep that one mainly because i like 
its Art Deco design.Sometimes bring it to local Ag Fair to display among 
the gear from that era.

Content by Scott
Typos by Siri

On Sep 8, 2018, at 8:11 PM, William H. Fite  wrote:



Gentlemen, I've found this discussion interesting and informative. This
household works on quantum information theory rather than engineering so
there is much for us to learn.

I must observe that if an event takes out the entire GPS system (which a
Carrington event would not do) we will have issues a great deal more
immediate and pressing than getting hyper-precise timing systems restored.

And speaking of Carrington events, how many of us have our equipment
surrounded by Faraday cages and supplied with off-grid power? Because
without those, we won't have instruments to measure T at home or even in
a great many labs and businesses.

Just a thought.




> On Saturday, September 8, 2018, Dana Whitlow  wrote:
> 
> I argue that when the "big one" happens, getting back to where we are
> technologically
> will be in large part a bootstrapping kind of affair.  And I believe that
> starting off with
> WWV* will be a far better starting point than starting with sun clocks and
> dripping
> water.
> 
> Dana
> 
> 
> On Sat, Sep 8, 2018 at 5:54 PM, Ruslan Nabioullin 
> wrote:
> 
>>> On Fri, Sep 7, 2018 at 8:32 PM Bob kb8tq  wrote:
>>> 
>>> This is Time Nuts, not end of the world nuts …..
>>> ...
>>> I think we’ve all heard plenty of “the world is ending” stuff.
>>> 
>> 
>> But the availability of a T service under adverse conditions and the
>> ability of a system which consumes a T reference to gracefully degrade
>> its functionality upon degradation or absence of reference input(s) are
>> features/figures of merit---I do not see how discussion of that aspect
> can
>> be considered to be offtopic.
>> 
>> -Ruslan
>> 
>> --
>> Ruslan Nabioullin
>> Wittgenstein Laboratories
>> rnabioul...@gmail.com
>> (508) 523-8535
>> 50 Louise Dr.
>> Hollis, NH 03049
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-- 
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when it deserves it.
--Mark Twain

We may be surprised at the people we find in heaven. God has a soft spot
for sinners. His standards are quite low.
--Desmond Tutu
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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

This is precisely the scenario even a short GPS blackout of 1-2 weeks would 
cause.   Its not that GPS is not the finest time transfer system ever devised.  
 Its that with the loss of legacy systems we’ve lost the ability to degrade 
gracefully.

With a eLORAN system cell networks during a prolonged outage would probably 
degrade to 3G,  but they would still be up.   No you cant stream HD video or 
play GTA Online X,  but talk,text email and Facebook would still work Time 
transfer for most applications would still work.  The HFT boyos on Wall St 
would be SOL.  Not sure how to evaluate that eventuality.


People like US need to educate political and business leadership on the need 
for BACKUPS to GPS mainly because things like the Carrington Event have 
happened before and WILL happen again. 

   And having terrestrial systems mean that you can get techs onsite to repair 
by horse if necessary unlike a space based system where some idiot retired the 
fleet of repair trucks. So the only remaining option is to launch new ones.


On Sep 8, 2018, at 10:25 AM, jimlux  wrote:

> On 9/7/18 10:05 PM, John Reid wrote:
> Hi all,
> discussion of how to keep accurate time without access to GPS seems very
> on topic to me.
> These people involved in major catastrophe ('end of the world' as you
> put it) scenarios have a wealth of experience in other ways of keeping
> accurate time.


Actually, they don't necessarily have a wealth of experience, because they may 
have marched themselves down a path where they have a *requirement* for much 
better timing than they realize, because it is so easy and cheap to get good 
time today.

Imagine this scenario - you're a bank, and you batch process checks and 
deposits in one physical location, so you don't much care about when the check 
was written or the deposit made.  Then you move to a distributed system across 
the US, where the reconciliation is done on the basis of the date of the 
transaction - still probably ok, because there are no transactions during 
non-business hours, so as long as you reconcile at 1AM, if transaction time 
stamps are off by 5 minutes, it doesn't matter.


Now say "we're going to charge you, the customer a fee, if your balance goes 
negative" and go to 24/7 operations, where transactions are journaled 
immediately, rather than batch processed at night  If a deposit that was made 
at 12:00 (but timestamped 12:05)  is followed by a withdrawal made at 12:03 
(but timestamped 12:00), you get unfairly charged the overdraft fee.

For small problems, banks have ways to "unwind" errors.  But if it becomes a 
systemic thing that's a problem.

So the bank sets up GPSDOs at each transaction point - problem solved.

Until GPS fails.



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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

You are SO convinced that GPS will ALWAYS be there,   I’m NOT (Think Carrington 
Event) and i’ve been part of a few disaster exercises where both Internet and 
GPS were considered ‘down’ for the exercise and these exercises are done in 
conjunction with the military so PPS was also ‘off the table’.

It was quite an eye opener to see how many networks could not keep time 
synchronized within 5 minutes much less 5 seconds because of the cheap XO’s 
used in servers and workstations(NTP will ALWAYS BE AVAILABLE).  Just like the 
old Sun workstations.

It was also fun watching the multimillion dollar Harris radios drift once they 
no longer had a 10 Mhz input from a GPSDO.   One would think the local timebase 
would be a bit better than it was.  

The older ‘Pacer Bounce’ and Falcon series radios did much better because they 
had good local timebases and made no assumptions of the availability of a 
external timebase.  Whereas the new radios depend upon it.

These exercises are intended to practice restoring government communications 
after a large scale natural disaster.And without readily available 
precision time it aint easy.

Its also fun watching executives realizing that their phone during the exercise 
is a paperweight useful only in weighting down stacks of Form 213’s

Its not for nothing that Symmetricom is building more 5071’s than HP/Agilent 
ever did.

On Sep 7, 2018, at 5:18 PM, Bob kb8tq  wrote:

Hi

You are not trying to run a cell system when checking your local oscillator 
against LORAN.
It’s two completely different things. The timing requirements of the modern 
systems are indeed
way past what LORAN can deliver. We’re not talking about 1970’s state of the 
art anymore. You
need a time source that is in the 10 ns range to keep this stuff running. 
Multiple microseconds of 
error in your timing source aren’t good enough for what they have up and are 
rolling out.  Full 
end of holdover spec on many of them is below 2 microseconds. Normal operation 
is under 100 ns.
Give the cell outfits another couple years and that’s all they will have on the 
air.


Bob

> On Sep 6, 2018, at 9:08 PM, Scott McGrath  wrote:
> 
> 
> As to eLORAN,  you can deny positioning but maintain timing service simply by 
> modifying the GRI and since eLORAN is software based thats not a difficult 
> change.
> 
> Navigation receivers go into fail but timing receivers only need ONE station. 
>   As the users of SRS700’s and Austrons do when Wildwood is active.
> 
> With GNSS its a hell of a lot harder and without SA your only option is to 
> turn off all the C/A signals hence denying civillian use of GNSS
> 
> I’m pretty sure if a non-state actor was doing weaponized drone attacks with 
> GPS for guidance,  GPS for civilian use would be shut down in a NY minute .
> 
> Remember govt users would not be affected as they have access to the PPS and 
> the ‘word of the day’ to make it active.
> 
> You dont need conspiracies to think of conditions where GPS would be shut 
> down for long periods of time and where reasonable people would agree with 
> the shutdown.
> 
> On Sep 6, 2018, at 8:44 PM, Scott McGrath  wrote:
> 
> Gee,  thats strange especially for those of us who ran the Austron 
> comparitors to check our local standards against the LORSTA’s
> 
> 
> 
> On Sep 6, 2018, at 8:04 PM, Bob kb8tq  wrote:
> 
> Hi
> 
> No, eLoran *never* on it’s best day could ever deliver the kind of timing 
> that the vast majority
> of these systems require. It simply is not and can not do the job. The world 
> has moved *way*
> past the sort of timing it can actually deliver. 
> 
> Bob
> 
>> On Sep 6, 2018, at 6:35 PM, Scott McGrath  wrote:
>> 
>> Actually we DID have a radio based system that provided sufficient accuracy 
>> it was called eLORAN but it was killed by US politicians because they did 
>> not want a much more inexpensive to operate system ‘competing’ with GPS.
>> Shutting down LORAN saved 32m dollars annually the NAVSTAR GPS program costs 
>> billions annually.
>> 
>> Ironically while LORAN’s absolute accuracy is less than GPS,  repeatability 
>> was much better so fishermen liked LORAN better.
>> 
>> Once again the empty suits won and the navigation and timing community lost.
>> 
>> Wrt cellsites staying operational i imagine the oscillators in holdover 
>> would probably remain sufficiently synchronized for a month or so.
>> 
>> 
>> 
>> On Sep 6, 2018, at 4:56 PM, Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> Well, we *do* have experience with that. It was called selective 
>> availability. Indeed it might get turned back on again. It’s impact on a 
>> properly designed GPSDO - not much. It takes a bit longer to get to best 
>> stability

Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

As to eLORAN,  you can deny positioning but maintain timing service simply by 
modifying the GRI and since eLORAN is software based thats not a difficult 
change.

Navigation receivers go into fail but timing receivers only need ONE station.   
As the users of SRS700’s and Austrons do when Wildwood is active.

With GNSS its a hell of a lot harder and without SA your only option is to turn 
off all the C/A signals hence denying civillian use of GNSS

I’m pretty sure if a non-state actor was doing weaponized drone attacks with 
GPS for guidance,  GPS for civilian use would be shut down in a NY minute .

Remember govt users would not be affected as they have access to the PPS and 
the ‘word of the day’ to make it active.

You dont need conspiracies to think of conditions where GPS would be shut down 
for long periods of time and where reasonable people would agree with the 
shutdown.

On Sep 6, 2018, at 8:44 PM, Scott McGrath  wrote:

Gee,  thats strange especially for those of us who ran the Austron comparitors 
to check our local standards against the LORSTA’s



On Sep 6, 2018, at 8:04 PM, Bob kb8tq  wrote:

Hi

No, eLoran *never* on it’s best day could ever deliver the kind of timing that 
the vast majority
of these systems require. It simply is not and can not do the job. The world 
has moved *way*
past the sort of timing it can actually deliver. 

Bob

> On Sep 6, 2018, at 6:35 PM, Scott McGrath  wrote:
> 
> Actually we DID have a radio based system that provided sufficient accuracy 
> it was called eLORAN but it was killed by US politicians because they did not 
> want a much more inexpensive to operate system ‘competing’ with GPS.
> Shutting down LORAN saved 32m dollars annually the NAVSTAR GPS program costs 
> billions annually.
> 
> Ironically while LORAN’s absolute accuracy is less than GPS,  repeatability 
> was much better so fishermen liked LORAN better.
> 
> Once again the empty suits won and the navigation and timing community lost.
> 
> Wrt cellsites staying operational i imagine the oscillators in holdover would 
> probably remain sufficiently synchronized for a month or so.
> 
> 
> 
> On Sep 6, 2018, at 4:56 PM, Bob kb8tq  wrote:
> 
> Hi
> 
> Well, we *do* have experience with that. It was called selective 
> availability. Indeed it might get turned back on again. It’s impact on a 
> properly designed GPSDO - not much. It takes a bit longer to get to best 
> stability. System time wise, it still works “good enough”. 
> 
> A four hour long test format also does basically nothing to a GPSDO based 
> system. You didn’t read anything in the papers about all cell service in 
> three states going away. The devices did what they are supposed to do and 
> everything did it’s boringly normal thing ….. it worked fine. 
> 
> I still don’t quite understand just what people think could replace satellite 
> based timing in these systems. None of the “radio based” systems are within a 
> factor many thousands to a few million of being adequate. 
> 
> =
> 
> Now, if this is headed off into a “the government is coming to break down the 
> doors and take away all my toys sort of thing. That’s very much *not* a Time 
> Nuts topic.
> 
> Bob
> 
>> On Sep 6, 2018, at 11:34 AM, Scott McGrath  wrote:
>> 
>> And there is the other significant vulnerability since GPS is a MILITARY 
>> system the DoD can take it offline for any reason at any time.  
>> 
>> Leaving civilian users with nothing, 
>> 
>> If its a national security threat its likely the other GNSS systems will be 
>> unavailable as well.
>> 
>> 
>> 
>> 
>> 
>> On Sep 6, 2018, at 9:53 AM, John Sloan  wrote:
>> 
>> 
>> Folks:
>> 
>> Well blow me down. It took some Google Maps fu on the web on my part, but
>> my time and place does indeed coincide with this “GPS Interference Testing” 
>> at
>> White Sands Missile Range. I just happened to be in my home office watching
>> several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham!
>> 
>> :John
>> 
>>> ZDV   DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV
>>> GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A
>>> 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM
>>> RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM
>>> RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230
>> 
>> --
>> J. L. SloanDigital Aggregates Corp.
>> +1 303 940 9064 (O)3440 Youngfield St. #209
>> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
>> jsl...@diag.comhttp://www.diag.com <http://www.diag.com/>
>&

Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

Gee,  thats strange especially for those of us who ran the Austron comparitors 
to check our local standards against the LORSTA’s



On Sep 6, 2018, at 8:04 PM, Bob kb8tq  wrote:

Hi

No, eLoran *never* on it’s best day could ever deliver the kind of timing that 
the vast majority
of these systems require. It simply is not and can not do the job. The world 
has moved *way*
past the sort of timing it can actually deliver. 

Bob

> On Sep 6, 2018, at 6:35 PM, Scott McGrath  wrote:
> 
> Actually we DID have a radio based system that provided sufficient accuracy 
> it was called eLORAN but it was killed by US politicians because they did not 
> want a much more inexpensive to operate system ‘competing’ with GPS.
> Shutting down LORAN saved 32m dollars annually the NAVSTAR GPS program costs 
> billions annually.
> 
> Ironically while LORAN’s absolute accuracy is less than GPS,  repeatability 
> was much better so fishermen liked LORAN better.
> 
> Once again the empty suits won and the navigation and timing community lost.
> 
> Wrt cellsites staying operational i imagine the oscillators in holdover would 
> probably remain sufficiently synchronized for a month or so.
> 
> 
> 
> On Sep 6, 2018, at 4:56 PM, Bob kb8tq  wrote:
> 
> Hi
> 
> Well, we *do* have experience with that. It was called selective 
> availability. Indeed it might get turned back on again. It’s impact on a 
> properly designed GPSDO - not much. It takes a bit longer to get to best 
> stability. System time wise, it still works “good enough”. 
> 
> A four hour long test format also does basically nothing to a GPSDO based 
> system. You didn’t read anything in the papers about all cell service in 
> three states going away. The devices did what they are supposed to do and 
> everything did it’s boringly normal thing ….. it worked fine. 
> 
> I still don’t quite understand just what people think could replace satellite 
> based timing in these systems. None of the “radio based” systems are within a 
> factor many thousands to a few million of being adequate. 
> 
> =
> 
> Now, if this is headed off into a “the government is coming to break down the 
> doors and take away all my toys sort of thing. That’s very much *not* a Time 
> Nuts topic.
> 
> Bob
> 
>> On Sep 6, 2018, at 11:34 AM, Scott McGrath  wrote:
>> 
>> And there is the other significant vulnerability since GPS is a MILITARY 
>> system the DoD can take it offline for any reason at any time.  
>> 
>> Leaving civilian users with nothing, 
>> 
>> If its a national security threat its likely the other GNSS systems will be 
>> unavailable as well.
>> 
>> 
>> 
>> 
>> 
>> On Sep 6, 2018, at 9:53 AM, John Sloan  wrote:
>> 
>> 
>> Folks:
>> 
>> Well blow me down. It took some Google Maps fu on the web on my part, but
>> my time and place does indeed coincide with this “GPS Interference Testing” 
>> at
>> White Sands Missile Range. I just happened to be in my home office watching
>> several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham!
>> 
>> :John
>> 
>>> ZDV   DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV
>>> GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A
>>> 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM
>>> RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM
>>> RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230
>> 
>> --
>> J. L. SloanDigital Aggregates Corp.
>> +1 303 940 9064 (O)3440 Youngfield St. #209
>> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
>> jsl...@diag.comhttp://www.diag.com <http://www.diag.com/>
>> 
>> 
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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

Actually we DID have a radio based system that provided sufficient accuracy it 
was called eLORAN but it was killed by US politicians because they did not want 
a much more inexpensive to operate system ‘competing’ with GPS.Shutting 
down LORAN saved 32m dollars annually the NAVSTAR GPS program costs billions 
annually.

Ironically while LORAN’s absolute accuracy is less than GPS,  repeatability was 
much better so fishermen liked LORAN better.

Once again the empty suits won and the navigation and timing community lost.

Wrt cellsites staying operational i imagine the oscillators in holdover would 
probably remain sufficiently synchronized for a month or so.



On Sep 6, 2018, at 4:56 PM, Bob kb8tq  wrote:

Hi

Well, we *do* have experience with that. It was called selective availability. 
Indeed it might get turned back on again. It’s impact on a properly designed 
GPSDO - not much. It takes a bit longer to get to best stability. System time 
wise, it still works “good enough”. 

A four hour long test format also does basically nothing to a GPSDO based 
system. You didn’t read anything in the papers about all cell service in three 
states going away. The devices did what they are supposed to do and everything 
did it’s boringly normal thing ….. it worked fine. 

I still don’t quite understand just what people think could replace satellite 
based timing in these systems. None of the “radio based” systems are within a 
factor many thousands to a few million of being adequate. 

=

Now, if this is headed off into a “the government is coming to break down the 
doors and take away all my toys sort of thing. That’s very much *not* a Time 
Nuts topic.

Bob

> On Sep 6, 2018, at 11:34 AM, Scott McGrath  wrote:
> 
> And there is the other significant vulnerability since GPS is a MILITARY 
> system the DoD can take it offline for any reason at any time.  
> 
> Leaving civilian users with nothing, 
> 
> If its a national security threat its likely the other GNSS systems will be 
> unavailable as well.
> 
> 
> 
> 
> 
> On Sep 6, 2018, at 9:53 AM, John Sloan  wrote:
> 
> 
> Folks:
> 
> Well blow me down. It took some Google Maps fu on the web on my part, but
> my time and place does indeed coincide with this “GPS Interference Testing” at
> White Sands Missile Range. I just happened to be in my home office watching
> several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham!
> 
> :John
> 
>> ZDV   DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV
>> GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A
>> 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM
>> RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM
>> RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230
> 
> --
> J. L. SloanDigital Aggregates Corp.
> +1 303 940 9064 (O)3440 Youngfield St. #209
> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
> jsl...@diag.comhttp://www.diag.com <http://www.diag.com/>
> 
> 
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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

And there is the other significant vulnerability since GPS is a MILITARY system 
the DoD can take it offline for any reason at any time.  

 Leaving civilian users with nothing, 

  If its a national security threat its likely the other GNSS systems will be 
unavailable as well.





On Sep 6, 2018, at 9:53 AM, John Sloan  wrote:


Folks:

Well blow me down. It took some Google Maps fu on the web on my part, but
my time and place does indeed coincide with this “GPS Interference Testing” at
White Sands Missile Range. I just happened to be in my home office watching
several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham!

:John

> ZDV   DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV
> GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A
> 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM
> RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM
> RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230

--
J. L. SloanDigital Aggregates Corp.
+1 303 940 9064 (O)3440 Youngfield St. #209
+1 303 489 5178 (M)Wheat Ridge CO 80033 USA
jsl...@diag.comhttp://www.diag.com 


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Re: [time-nuts] Lost GPS lock or 1PPS recently?

[Scott McGrath]

Actually. I have 6...   And a large assortment of directional antennas of many 
flavors LPDA, Horn etc,I have to get out there and find the interfering 
source.

Cable company has been having problems with ‘booster’ amplifiers installed by 
homeowners to ‘clean up’ noisy DTV signals.   So just imagine a cheap 
unshielded amp driven into clipping.

I live in the sticks so LightSquared or its successor  is unlikely to be the 
source in my case.



On Sep 4, 2018, at 3:18 PM, Dana Whitlow  wrote:

Scott & John,

Do either of you have any activity by "Light Squared" (or whatever it's now
called) in your area.  Jamming does not always have to be in-band to be
effective.

Dana


> On Tue, Sep 4, 2018 at 1:11 PM Scott McGrath  wrote:
> 
> My TrueTime DC-XL has lost lock since yesterday as has my Z3805 and my
> car’s onboard GPS will not lock since the 2’nd.  I need to get about a mile
> from home before Car’s nav system reports ready.
> 
> There has been a great deal of repair work on the local cable system so
> this is almost certainly related to that
> 
> But it proves my point about the fragility of GPS
> 
> 
> 
> 
> 
> On Sep 4, 2018, at 12:31 PM, John Sloan  wrote:
> 
> Folks:
> 
> GPS jamming and spoofing isn't really my area of expertise, but it's
> something I worry about, not just for its impact on geolocation and
> navigation applications, but also because GPS has become critical as a high
> precision timing reference in the telecommunications realm, which *is* my
> area of expertise.
> 
> Yesterday (2018-09-03) afternoon (about 22:00UTC, 16:00MDT) I noticed one
> of my three home-made GPS-disciplined NTP servers had lost its GPS lock.
> After some forensics on my part, this (2018-09-04) morning (about 16:00UTC,
> 10:00MDT) I replaced the amplified antenna, and the device reacquired its
> lock. I figured it was just an antenna failures; this is an amplified
> filtered antenna so it has active electronics.
> 
> Then just an hour or so later, I noticed one of my commercial
> GPS-disciplined NTP servers (TimeMachines) had lost the GPS 1PPS timing
> signal, but indicated it still had GPS lock. (I question now what this
> actually means in the context of this particular device). As a
> troubleshooting step, I power cycled the device, and it reacquired 1PPS.
> But as I did that, the second commercial GPS-disciplined NTP server
> (Uputronics) right next to it lit up with a red warning on its display,
> indicating it had lost GPS lock. A minute or so later it also reacquired
> lock and indicated 1PPS, with no action on my part.
> 
> All of these devices are completely independent, have different software
> (and probably hardware), have separate amplified antennas sitting side by
> side in the window of my home office, and are not all on the same
> electrical outlet (but may be on the same household circuit).
> 
> I lit up the LCD display on my little GPS monitoring tool I built that
> runs Lady Heather 24x7 and see on the graphical display sudden jumps of
> reduced timing accuracy of a factor of 10^2 (from nanoseconds to hundreds
> of nanoseconds) in the recent past. But I’m thinking this can also be
> caused just by the dynamic satellite geometry, and might be normal. It’s
> not like I watch this graph all the time (even though it does sit right in
> front of me on my desk).
> 
> No clue what's going on in my suburb near Golden Colorado. But I’m a
> little freaked out. Trying to figure out which rule, [1] It’s something
> stupid I’ve done, or [2] I am not unique, to apply.
> 
> :John
> 
> --
> J. L. SloanDigital Aggregates Corp.
> +1 303 940 9064 (O)3440 Youngfield St. #209
> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
> jsl...@diag.comhttp://www.diag.com <http://www.diag.com/>
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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

There was a paper published when NASA did something similar for LC39 and the 
VAB.Anyone have a copy because the link i have is dead.

As I recall it was some trick and compensating for thermal effects on the fiber 
itself was a large part of the effort.



On Sep 1, 2018, at 5:29 AM, Magnus Danielson  wrote:

Hi,

It was very telling when I crashed a research group into the reality of
phase/time transfer over fiber compared to frequency transfer. Armed
with a whiteboard and pens, I derived the forumulas and showed how they
worked and not worked. It's a completely different ball-game and their
"known tricks" ain't doing nothing good as it comes to time.

I had to figure much of this out myself as I did nation-wide system
design to achieve the goal. It's a combination of many skills that goes
into designing the full system from scratch and make it fit together.
It's not hard stuff, it's just many details one needs to get right.

Oh the fun.

Cheers,
Magnus

> On 08/31/2018 05:15 PM, Bob kb8tq wrote:
> Hi
> 
> That works fine if you are doing things manual to check a local standard. If 
> you are trying to 
> disipline a few thousand cell towers 24 hours a day … not so much. It also 
> works for 
> checking frequency. What modern systems need is time. That gets you into a 
> whole 
> world of resolving and identifying individual edges. The WWVB signal really 
> was never
> set up for this. Loran-C is an example of a signal that was designed to 
> identify a specific
> edge.
> 
> Bob
> 
>> On Aug 31, 2018, at 10:30 AM, Martin VE3OAT  wrote:
>> 
>> But the diurnal phase shifts at VLF are predictable and largely repeatable.  
>> Ignore the phase at night and use only the phase records during the day when 
>> an all-daylight propagation path exists.  You might have to "correct" the 
>> absolute phase reading by some multiple of the RF period, but with a low 
>> rate of local standard oscillator drift, this is a simple matter of 
>> arithmetic. Back in the day, I managed Sulzer crystal oscillators at 5 field 
>> sites from my office and could maintain phase continuity for weeks at a 
>> time, until we had to diddle the dial on one or several of them to correct 
>> for crystal aging.  Then it was just more arithmetic again.  Several of the 
>> oscillators had such low drift rates that all I needed was one daily phase 
>> reading from the VLF phase tracking receiver (Tracor 599Js) at those sites 
>> to know the frequency of the Sulzers there.
>> 
>> ... Martin VE3OAT
>> 
>> On Thu, 30 Aug 2018 12:27:12 -0400
>> Bob kb8tq  wrote:
>> 
>>> WWVB as transmitted ( = right at the input to the antenna) is a wonderfully 
>>> stable signal. As soon as
>>> that signal hits the real world things start to degrade. Propagation 
>>> between transmit and receive sites
>>> is a big deal, even at 60 KHz. On top of that, there is a*lot*  of manmade 
>>> noise at 60 KHz. The receive
>>> signal to noise will never be as good as you might like it to be ?.
>> 
>>> I don't know about WWVB, but for DCF77 it's known that sunrise/sunset
>>> causes a phase shift of several 100?s at even moderate distances
>>> (like ~500km). Unfortunately I don't have any measurements at hand.
>>>Attila Kinali
>> 
>> 
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Re: [time-nuts] Effects of Simple GPS jamming on GPSDO's ?

[Scott McGrath]

That’s the scenario i’m most concerned with not war or terrorism but a natural 
event which has occurred before and will occur again.

Rebooting technology will be a heck of a lot easier with a variety of precision 
time/frequency distribution methods.

After a Carrington type event a working Cs or Rb will be worth several times 
their weight in gold.

Its not that I’m nostalgic for the old days but having a HF frequency source 
will allow HF networks to determine propagation .

Content by Scott
Typos by Siri

On Aug 31, 2018, at 6:38 PM, Dana Whitlow  wrote:

I'm thinking about if/when "the big one hits" and takes out most or all of
the GPS
sats, cell phone systems, etc.

Then the time required to reboot up to a reasonable level of technology
might turn
out to be limited by our ability to determine time and freq somewhat
accurately.  The
better we can do from scratch, the faster the reboot.

So one question is:  how many Cs beam clocks are out there which are kept
running
and "on time", at least by frequent logging of errors if not by actual
setting/tweaking?

If "the big one" is global nuclear war, of course we'll all have far more
to worry about
than keeping our watches accurately set.  But what if it's another
Carrington-level
event?  I'm sure we'd all like to get back to business as usual as quickly
as possible.

Dana


> On Fri, Aug 31, 2018 at 5:23 PM Bob kb8tq  wrote:
> 
> Hi
> 
> I think we have a little bit of confusion here. WWVB is not going to help
> anybody navigate.
> It’s not going to help track people with ankle bracelets or trucks
> stopping at bars. Car thieves
> jamming Lojack still happens. Turn iWWVB on or off, this stuff still goes
> on. None of this is
> a Time Nuts sort of issue.
> 
> The only thing WWVB *might* do is provide timing. That’s very different
> than navigation. A
> mobile this or that driving by puts your GPSDO into holdover. It maintains
> time while it is in
> holdover. Minutes or hours, possibly days … works the same way. The system
> keeps running
> just like GPS was doing fine. If after a day or more, the GPS is still
> jammed, that single  cell tower
> shuts down. Take out one cell tower and the system keeps running. There is
> a lot of overlap on
> these systems. Towers go down a lot more often than you might think …..
> 
> Do all systems work identically in terms of timing? Of course not. If
> timing is critical to operation,
> systems do use GPSDO’s. The same basic principles apply. The main question
> would be one
> of overlap between elements of the system.
> 
> The same jamming that takes out GPS for timing also takes it out for
> normal navigation. Take
> it out over an entire city and everybody’s vehicle navigation system goes
> out. Do that even for
> a couple of hours and it’s on the evening news. Do that for a day and
> there *is* a response.
> That’s the kind of thing needed to impact utility systems (like cell
> towers) in a significant way.
> It simply does not happen ….City wide is very hard to do from the ground.
> From the air, you
> can get the coverage. It’s tough to keep doing it from the air for days on
> end.
> 
> So, interns of “the world ends if / when WWVB turns off” … not so much.
> 
> In terms of the initial question, GPSDO’s in general are pretty good at
> handling the typical
> jamming they might run into.
> 
> Bob
> 
> 
> 
>> On Aug 31, 2018, at 3:52 PM, Scott McGrath  wrote:
>> 
>> And here is one of the schematics running around the ‘net.   This one is
> noise based
>> 
>> 
>> 
>> 
>> 
>> On Aug 31, 2018, at 3:41 PM, Gerhard Hoffmann  wrote:
>> 
>> 
>> 
>>>> Am 31.08.2018 um 19:39 schrieb jimlux:
>>>> On 8/31/18 10:15 AM, Bob kb8tq wrote:
>>>> Hi
>>>> 
>>>> Having spent a lot of my life designing GPSDO’s it’s a “that depends”
> sort of thing.
>>>> For a simple noise jammer, yes, they pretty much all will go into
> holdover. When the
>>>> jammer goes away, they come out of holdover. There are a few older
> units that may not
>>>> do quite as well with various sorts of broadband jamming.  With a
> spoofing jammer that is flying
>>>> around overhead and simulating an entire constellation … you could see
> any of them do odd
>>>> things. An airborne jammer flying over this or that city likely gets
> you into a “act of war” sort of issue.
>>>> It’s something you build if you are a nation state.
>>>> 
>>>> The performance with noise jammers is not a guess. It’s based on field
> experience and
>>>> all those never ending meetings I keep referring to …..
>>>> 
>> IIRC, ther

Re: [time-nuts] WWV and legal issues

[Scott McGrath]

Strangely enough there are these devices called ‘computers’ which are rumored 
to be able to perform measurements and mathematical calculations.

One of these ‘computers’ might be profitably employed to perform the necessary 
measurements calculations and deliver a useful output,   

Employing a Mentat would be expensive for this task...


On Aug 31, 2018, at 11:37 AM, Tom Holmes  wrote:

Uh, folks...Would the apparently still on hiatus TVB approve of this on-going 
Urinary Olympiad? Just asking. And hoping post this won’t start another one.

Tom Holmes, N8ZM

-Original Message-
From: time-nuts  On Behalf Of Bob kb8tq
Sent: Friday, August 31, 2018 11:16 AM
To: Martin VE3OAT ; Discussion of precise time and frequency 
measurement 
Subject: Re: [time-nuts] WWV and legal issues

Hi

That works fine if you are doing things manual to check a local standard. If 
you are trying to 
disipline a few thousand cell towers 24 hours a day … not so much. It also 
works for 
checking frequency. What modern systems need is time. That gets you into a 
whole 
world of resolving and identifying individual edges. The WWVB signal really was 
never
set up for this. Loran-C is an example of a signal that was designed to 
identify a specific
edge.

Bob

> On Aug 31, 2018, at 10:30 AM, Martin VE3OAT  wrote:
> 
> But the diurnal phase shifts at VLF are predictable and largely repeatable.  
> Ignore the phase at night and use only the phase records during the day when 
> an all-daylight propagation path exists.  You might have to "correct" the 
> absolute phase reading by some multiple of the RF period, but with a low rate 
> of local standard oscillator drift, this is a simple matter of arithmetic. 
> Back in the day, I managed Sulzer crystal oscillators at 5 field sites from 
> my office and could maintain phase continuity for weeks at a time, until we 
> had to diddle the dial on one or several of them to correct for crystal 
> aging.  Then it was just more arithmetic again.  Several of the oscillators 
> had such low drift rates that all I needed was one daily phase reading from 
> the VLF phase tracking receiver (Tracor 599Js) at those sites to know the 
> frequency of the Sulzers there.
> 
> ... Martin VE3OAT
> 
> On Thu, 30 Aug 2018 12:27:12 -0400
> Bob kb8tq  wrote:
> 
>> WWVB as transmitted ( = right at the input to the antenna) is a wonderfully 
>> stable signal. As soon as
>> that signal hits the real world things start to degrade. Propagation between 
>> transmit and receive sites
>> is a big deal, even at 60 KHz. On top of that, there is a*lot*  of manmade 
>> noise at 60 KHz. The receive
>> signal to noise will never be as good as you might like it to be ?.
> 
>> I don't know about WWVB, but for DCF77 it's known that sunrise/sunset
>> causes a phase shift of several 100?s at even moderate distances
>> (like ~500km). Unfortunately I don't have any measurements at hand.
>>Attila Kinali
> 
> 
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Re: [time-nuts] GNSS beam forming (was: NIST)

[Scott McGrath]

I/We track down things that jam weather radars.  Mostly WiFi access points 
misconfigured.   

Which share many of the characteristics of GPS jammers

1 - small low powered
2 - one can ruin a pilots entire day
3 - distributed
4 - can literally be anywhere

Stuff like this is why FCC blocked anyone but chip manufacturers from updating 
WiFi radio firmware.

The overwhelming majority of the mods were attempts to improve performance.   
But the firmware hackers were unaware of the band sharing and also did not 
understand that signal characteristics need to be closely controlled and the 
limits the FCC applies are not there to ‘ruin my performance’ but to allow 
others to play nicely in that sandbox.

So many things in life should have been learned in kindergarten.  Sadly many 
have forgotten those lessons.

On Aug 31, 2018, at 10:55 AM, Attila Kinali  wrote:

On Thu, 30 Aug 2018 23:05:48 +
Gregory Maxwell  wrote:


> Seeing some open source software implementing beam-forming was one of
> the things I hoped to see result from the open hardware multi-band
> GNSS receivers like the GNSS firehose project (
> http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once
> you're going through the trouble of running three coherent receivers
> for three bands, stacking three more of them and locking them to the
> same clock doesn't seem like a big engineering challenge... and the
> rest is just DSP work.

"Just DSP work" is a tad bit more than you think. You are dealing
with sevaral 1Msps of data, even for a simple L1 C/A receiver.
If you are going multi-band-multi-GNSS you are usually in the 50MHz BW
at L1 and 80MHz BW at L2/L5 range, which means you are dealing with
something in the order of 100Msps of data per channel (either as
a single stream of sample or two streams of samples with half rate).
Then you add to it that you will need at least 4bit ADCs to get
somewhat jaming proof, probably even 10bit or more and suddenly
you are dealing with 200-400Mbyte/s data per antenna. Constantly.
To be able to do reasonable beam forming, you probably need a 4 by 4
grid at least, that makes 16 antennas which brings us into the
3Gbyte/s to 6Gbyte/s region. And that's just the raw _input_ datarate 
you have to handle  A modern GNSS receiver has something in the
order of 50-100 correlators per band, each of which needs to receive 
the full data rate mentioned above. So inside the chip, the data rate
gets multiplied as well.

Now take into considerations that beside running the correlators,
after you phase shifted and weighted the inputs correctly, you
have to run some fancy algorithms (on the raw data) to figure
out what these phase shifts and weights are. For each satellite
you are tracking individually. All this toghether means you have
run some pretty heavy computation, that is very likely not going
to fit into an FPGA, so you need to build a custom ASIC.



> Even absent fancy beam forming, for GNSS timing with a surveyed
> position except at high latitudes it should be possible to use a
> relatively high gain antenna pointed straight up and by doing so blind
> yourself to terrestrial jammers at a cost of fewer SVs being
> available. But I've never tried it.

You still need the lower satellites to survey your position accurately.
Besides that you lose a lot of in terms of timing accuracy, if you
have only a limited number of satellites. So you cannot decrease the
lower elevation angles too much. Going below -10dB is probably not
agood idea. Also, going from ~10 birds in view down to ~5 means that
your PPS jitter just increased by a factor of 5 to 10. 
(source: experiment i've done here some time ago)

Besides, a narrow band jammer trips up most of the commercial receivers
badly (adds a correlation peak where it does not belong).
And for that to be effective you only need to be 5-10dB above the noise
level. Which is pretty easy to achieve, even if you have very directive
antenna (the sidelobes are usually only 10-30dB down from the main lobe)

Fortunately, narrow band jammers are also pretty easy to mask, given
you have enough bits in your ADC.

> As others have noted intermittent jamming is pretty benign to a GPSDO.
> Spoofing, OTOH, can trivially mess up the timing.  It's my view that
> if you need timing for a security critical purpose there isn't really
> any GNSS based solution commercially available to the general public
> right now, the best bet is a local atomic reference with a GPSDO used
> to monitor and initially set it.

There is a reason why Microsemi is building more 5071 these days than
ever before (rumors have it that they are are 3-4 devices per week).

   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, Neal Stephenson

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Re: [time-nuts] NIST

[Scott McGrath]

Just ask the NY Port authority how ‘easy’ knocking these jammers offline is.   
Usually done by vehicle to vehicle inspection with a SA.

And yes the day job all too frequently searching for and identifying 
interference sources.

One of the more interesting ones was a halogen leak detector wiping out WiFi at 
a manufacturing plant.   So my opinions on interference location are informed 
by leading teams of people doing just that.

Content by Scott
Typos by Siri

On Aug 30, 2018, at 8:24 PM, Bob kb8tq  wrote:

Hi

Since timing receivers are actually going to prefer high angle sats, an antenna 
that rejects 
close to the horizon is a pretty common thing. Enhancing that sort of rejection 
doesn’t take 
a lot of effort. 

Bob

> On Aug 30, 2018, at 7:05 PM, Gregory Maxwell  wrote:
> 
> On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke  wrote:
>> I would disagree in that ease of jamming/spoofing is strongly related to 
>> wavelength.  That's because antenna efficiency
>> goes down as the size of the antenna gets smaller than 1/4 wave.
>> So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 
>> wavelength is a few inches, something that  you can
>> hold in your hand.
> 
> However, the short wavelengths of GPS make beam forming a reasonable
> countermeasure against jamming.
> 
> By having a small array of GPS antennas a receiver can digitally form
> beams that both aim directly at the relevant satellites (so even
> reducing intersatellite interference) while also steering a deep null
> in the direction of the jammer.  If the jammer is powerful enough to
> overload the front-end then this won't help, but against a
> non-targeted area denying jammer it should be fairly effective.
> 
> There are many papers on GNSS beamforming. ( e.g.
> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/
> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ )
> 
> This kind of anti-jamming solution should even be pretty inexpensive
> -- really no more than the cost of N receivers. Except that it is
> specialized technology and thus very expensive. :)
> 
> Seeing some open source software implementing beam-forming was one of
> the things I hoped to see result from the open hardware multi-band
> GNSS receivers like the GNSS firehose project (
> http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once
> you're going through the trouble of running three coherent receivers
> for three bands, stacking three more of them and locking them to the
> same clock doesn't seem like a big engineering challenge... and the
> rest is just DSP work.
> 
> Even absent fancy beam forming, for GNSS timing with a surveyed
> position except at high latitudes it should be possible to use a
> relatively high gain antenna pointed straight up and by doing so blind
> yourself to terrestrial jammers at a cost of fewer SVs being
> available. But I've never tried it.
> 
> In an urban area I noticed my own GPSDOs losing signal multiple times
> per week. Monitoring with an SDR showed what appeared to be jammers.
> 
> As others have noted intermittent jamming is pretty benign to a GPSDO.
> Spoofing, OTOH, can trivially mess up the timing.  It's my view that
> if you need timing for a security critical purpose there isn't really
> any GNSS based solution commercially available to the general public
> right now, the best bet is a local atomic reference with a GPSDO used
> to monitor and initially set it.
> 
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Re: [time-nuts] NIST

[Scott McGrath]

As Brooke notes while low frequency jammers are possible, practicality is 
another matter,   All it takes to jam a city scale area is a box the size of a 
pack of cigarettes.Because the GPS signal is very, very weak.

As an intentional denial put a couple hundred on stray animals.Now track 
those jammers down.

I doubt if any agency owns enough DF equipment to find them all in a reasonable 
amount of time.

Thats why we need backup systems and each backup system will have less and less 
accuracy as it increases in robustness.   The HF systems could provide adequate 
syncing for the Market example.



On Aug 30, 2018, at 6:18 PM, Poul-Henning Kamp  wrote:


In message <96e995c4-5ca2-af02-9738-0a6d87a9f...@pacific.net>, Brooke Clarke 
writes:

> But it's extremely hard to make a jammer for WWVB (60 kHz) [...]

You can do it city-scale with a 18-wheeler sized loop-antenna
and a good size diesel-generator.

However pedestrians will very likely note metalic items vibrating
as they pass the "mystery white truck".

Sweden were much more serious about it:

   http://www.antus.org/RT02.html

Tl;drs:

They erected 9 200m tall Loran-C class antennas each driven by
a Loran-C transmitter with an advanced degree which could jam
Loran-C or Chayka.

They even mounted decoy parabolas on the towers them to hide their
true purpose.

The fact that all the transmitters were on the east coast does drop
a hint that swedens much touted neutrality had a bit of a slant.

-- 
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] NIST

[Scott McGrath]

The port of Long Beach CA was jammed wrt GPS for several months by a 
malfunctioning 29.95 TV preamplifier on a boat.

GPS was completely unusable when this unsuspecting guy was watching TV on his 
boat.

He had quite the surprise when the coasties with guns showed up.

The fact is civillian GPS Is trivial to jam and jammers can be bought ‘under 
the counter’ at any truckstop along with illlegal linear amplifiers.



On Aug 30, 2018, at 12:58 PM, Peter Laws  wrote:

On Mon, Aug 13, 2018 at 8:52 AM Peter Laws  wrote:


> I have yet to hear anyone make a case for retaining the HF system that
> isn't backed by nostalgia.

Still looking for this.  Most of the "OMG IF WWV GOES AWAY MILLIONS
WILL DIE" posts (elsewhere, not here ... quite ...) are the type of
hysteria that is usually reserved for, I don't know, the EMP folks.
:-)


> As for solar flares taking out the various GNSSs ... wouldn't a solar
> flare only take out the vehicles that were on the "sunny" side of the
> Earth?  Wouldn't the (approximately) half of the SVs that are in the
> Earth's shadow be unaffected?  Serious technical question - I have no
> idea.

One of the responses to my initial message pointed out that the
effects of solar flares and CMEs take a while to get from Sol to Sol
III and don't arrive all at once, so potentially all GNSS spacecraft
could be affected.

Since then, I've been poking around for papers on the effect
(observed, potential, theoretical) of these events on the Navstar or
other GNSS constellations but am not having much luck.  I assume it's
because I'm not putting the right magic incantation into the google
machine.

Anyone got some cites?  Looking for the effect of solar flares and
CMEs on the spacecraft themselves and not how the GNSSs can be used to
measure the effects on the ionosphere, etc (those seem plentiful).
IOW, I'm curious about the resiliency of the systems to solar events.

I did note that at the time of the 1989 solar event that took out a
lot of Hydro Quebec's grid, only the "Block I" experimental GPS "SVs"
were in orbit.  Well, maybe a couple of the later ones - the
operational constellation started launching about a month before that
flare.

As I said initially, I'll be sad if WWV* goes away but it won't affect
my life in any measurable way that I can see.  I mean, other than the
mantle clock slowly losing time.

-- 
Peter Laws | N5UWY | plaws plaws net | Travel by Train!

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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

One does not get the same instantaneous accuracy that one gets from GPS but 
with a long baseline the offsets to your site can be determined.With eLoran 
you can  get similar levels of accuracy as the old Austron monitors used to 
prove

Content by Scott
Typos by Siri

On Aug 30, 2018, at 12:27 PM, Bob kb8tq  wrote:

Hi

WWVB as transmitted ( = right at the input to the antenna) is a wonderfully 
stable signal. As soon as
that signal hits the real world things start to degrade. Propagation between 
transmit and receive sites
is a big deal, even at 60 KHz. On top of that, there is a *lot* of manmade 
noise at 60 KHz. The receive 
signal to noise will never be as good as you might like it to be ….

60 KHz has a period of 16.667 us. GPS gives you ~10 ns sort of time quite 
quickly. Resolving the WWVB
carrier to that level is a major challenge. Identifying a single “cycle edge” 
as the magic timing ID with either
the old or new modulation formats …. yet another significant challenge. Net 
result is that you just can’t 
get the same sort of timing out of WWVB.

Bob

> On Aug 30, 2018, at 11:15 AM, Mike Bafaro  wrote:
> 
> According to what I have heard the 60KHz WWVB carrier is guaranteed accurate 
> to the atomic standard and is considered traceable.  I remember when I was in 
> the Navy years ago I remember taking our unit's HP5245L for calibration and 
> they used a VLF tracking receiver at 60KHz to do the calibration.  If WWVB 
> goes off the air what is the replacement for the 60KHz standard?
> 
> Mike
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Perry 
> Sandeen via time-nuts
> Sent: Wednesday, August 29, 2018 6:34 PM
> To: time-nuts@lists.febo.com
> Cc: Perry Sandeen
> Subject: [time-nuts] WWV and legal issues
> 
> Yo Dudes!�
> WWV and all its variations distribute what in the USA is the legal standard 
> of time (from USNO) and frequency (NIST).
> �If one is running a freq cal service IIRC it is a legal requirement to be 
> able to have traceability to WWV.
> 
> If one was to rely on other sources, one has no guarantee that it 1. It is as 
> accurate as claimed and 2. It can't be *diddled* with accidentally or 
> deliberately.
> Although GPSDO's are very good and popular, they come from satellites that 
> are vulnerable to damage from earth based resources.
> When your time and frequency standard(s) is under control on your own 
> physical territory then they stand or fail on their own.�
> After the atom bombing of Hiroshima and Nagasaki, one of the major inventors 
> of the bomb (I don't remember who) went to see US president Harry Truman and 
> essentially told him that the scientists who developed the bomb should have a 
> say of how or when it should be used.
> Truman is reported to have said for him to leave his office and told an aid 
> that was responsible for his schedule to "never in hell let that (or any 
> other) scientist� come to his office to influence American defense policy."
> Considering its status from both a scientific and political perspective, 
> IMNSHO it will go on as before.
> To explain the political. No government official wants to see China or the 
> Russian federation tell the world quote: See, the USA can't be trusted for 
> something as important and simple as frequency and time.� However we are your 
> friends who you can trust. Unquote.
> Regards,
> 
> 
> 
> 
> 
> This is a case of practical use of WWV albeit over 50 years a go the 
> fundamentals are still valid today.
> At Karamursel Air station TUSLOG 234 I was assigned to the base receiver 
> site.� Our base had to purposes.� to� �
> 
> 
> 
> 
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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

Bingo - we have a a Winner!!!

In a prior life as an architect at a northeastern we had Cs clocks, multiple 
GPS based NTP servers and CDMA NTP servers as TIME was the public key for all 
the crypto systems the Cs clocks were there in case GPS ‘went away’ for any 
reason and with service reliability as the primary goal  instead of ‘maximizing 
shareholder value’ we made sure that precision timing could survive anything 
short of total destruction of the campus and our backup sites.



On Aug 30, 2018, at 11:04 AM, James C Cotton  wrote:


Time is the public key for a lot of the crypto that runs on networks.


Any large university or corporation has multiple GPS based time sources and 
compares them to others...


Back in the mid-1980's a fire in a CO in East Lansing, MI and a backhoe in 
Jackson, MI took out the Internet connections

at the university I work at.  A couple of routers using time as the public key 
and exchanging encrypted routing packets were

isolated.


Jim Cotton


From: time-nuts  on behalf of Scott McGrath 

Sent: Thursday, August 30, 2018 10:42:45 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] WWV and legal issues

Um no

Will the internet continue to route packets without precision timing yes it 
will,  Yes the lambdas will stay lit on fiber but the ATM transport that runs 
on the lambdas will fail (note DSL is simply an ATM VC over copper).  and other 
timing dependent services will fail

Will many services like authentication continue especially those based on 
multimaster replication continue to function?

No they will not,  they are totally dependent on precision timing to ensure 
proper replication sourcing. (Microsoft Active Directory)

Banking transactions in the same boat.

Unless you’ve actually run a large network you dont realize just how dependent 
on precision timing the services running over the network have become 
especially authentication And one reason for this is increased security for the 
overall network.

On Aug 30, 2018, at 8:45 AM, Brian Lloyd  wrote:

On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath  wrote:

> 
> 
> 
> Without precision timing there is no telephone network, cell phones or
> internet.   And that only became true in the last 20 years or so as long
> haul networks went from FDM on coaxial cable to TDM on fibre.
> 

The Internet is largely asynchronous due to the store-and-forward nature of
the routers. Fiber capacity is increased through the use of wavelength
division multiplexing (WDM) which is itself a form of FDM. The Internet
functions without any sort of central synchronization.

Yes, there are portions that run over the synchronized telco services but
that is by convenience, not necessity.

--



Brian Lloyd
706 Flightline
Spring Branch, TX 78070
br...@lloyd.aero
+1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

Um no

Will the internet continue to route packets without precision timing yes it 
will,  Yes the lambdas will stay lit on fiber but the ATM transport that runs 
on the lambdas will fail (note DSL is simply an ATM VC over copper).  and other 
timing dependent services will fail

 Will many services like authentication continue especially those based on 
multimaster replication continue to function?

No they will not,  they are totally dependent on precision timing to ensure 
proper replication sourcing. (Microsoft Active Directory)

Banking transactions in the same boat.

Unless you’ve actually run a large network you dont realize just how dependent 
on precision timing the services running over the network have become 
especially authentication And one reason for this is increased security for the 
overall network.

On Aug 30, 2018, at 8:45 AM, Brian Lloyd  wrote:

On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath  wrote:

> 
> 
> 
> Without precision timing there is no telephone network, cell phones or
> internet.   And that only became true in the last 20 years or so as long
> haul networks went from FDM on coaxial cable to TDM on fibre.
> 

The Internet is largely asynchronous due to the store-and-forward nature of
the routers. Fiber capacity is increased through the use of wavelength
division multiplexing (WDM) which is itself a form of FDM. The Internet
functions without any sort of central synchronization.

Yes, there are portions that run over the synchronized telco services but
that is by convenience, not necessity.

-- 



Brian Lloyd
706 Flightline
Spring Branch, TX 78070
br...@lloyd.aero
+1.210.802-8FLY (1.210.802-8359)
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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

A DIY radio distribution system is not secure and traceable to NIST/USNO even 
if the source is GPS.



On Aug 29, 2018, at 7:52 PM, Scott McGrath  wrote:

Excellent point on LEGAL time,  The problem is as always is GPS is the new 
shiny object.

You mentioned earth based hostile actors.   But a really large solar flare or 
CME has the potential to take out or severely degrade ALL the GNSS systems.  

Something on the order of the ‘Carrington Event’ or the flare in 1989 which 
took out power to much of Canada.   

Things like this are why we need terrestrial time distribution systems like 
eLORAN which by its nature is resistant to both man made and natural 
interference.

On Aug 29, 2018, at 7:33 PM, Perry Sandeen via time-nuts 
 wrote:

Yo Dudes! 
WWV and all its variations distribute what in the USA is the legal standard of 
time (from USNO) and frequency (NIST).
If one is running a freq cal service IIRC it is a legal requirement to be able 
to have traceability to WWV.

If one was to rely on other sources, one has no guarantee that it 1. It is as 
accurate as claimed and 2. It can't be *diddled* with accidentally or 
deliberately.
Although GPSDO's are very good and popular, they come from satellites that are 
vulnerable to damage from earth based resources.
When your time and frequency standard(s) is under control on your own physical 
territory then they stand or fail on their own. 
After the atom bombing of Hiroshima and Nagasaki, one of the major inventors of 
the bomb (I don't remember who) went to see US president Harry Truman and 
essentially told him that the scientists who developed the bomb should have a 
say of how or when it should be used.
Truman is reported to have said for him to leave his office and told an aid 
that was responsible for his schedule to "never in hell let that (or any other) 
scientist  come to his office to influence American defense policy."
Considering its status from both a scientific and political perspective, IMNSHO 
it will go on as before.
To explain the political. No government official wants to see China or the 
Russian federation tell the world quote: See, the USA can't be trusted for 
something as important and simple as frequency and time.  However we are your 
friends who you can trust. Unquote.
Regards,





This is a case of practical use of WWV albeit over 50 years a go the 
fundamentals are still valid today.
At Karamursel Air station TUSLOG 234 I was assigned to the base receiver site.  
Our base had to purposes.  to   




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Re: [time-nuts] WWV and legal issues

[Scott McGrath]

Excellent point on LEGAL time,  The problem is as always is GPS is the new 
shiny object.

You mentioned earth based hostile actors.   But a really large solar flare or 
CME has the potential to take out or severely degrade ALL the GNSS systems.  

Something on the order of the ‘Carrington Event’ or the flare in 1989 which 
took out power to much of Canada.   

Things like this are why we need terrestrial time distribution systems like 
eLORAN which by its nature is resistant to both man made and natural 
interference.

On Aug 29, 2018, at 7:33 PM, Perry Sandeen via time-nuts 
 wrote:

Yo Dudes! 
WWV and all its variations distribute what in the USA is the legal standard of 
time (from USNO) and frequency (NIST).
 If one is running a freq cal service IIRC it is a legal requirement to be able 
to have traceability to WWV.

If one was to rely on other sources, one has no guarantee that it 1. It is as 
accurate as claimed and 2. It can't be *diddled* with accidentally or 
deliberately.
Although GPSDO's are very good and popular, they come from satellites that are 
vulnerable to damage from earth based resources.
When your time and frequency standard(s) is under control on your own physical 
territory then they stand or fail on their own. 
After the atom bombing of Hiroshima and Nagasaki, one of the major inventors of 
the bomb (I don't remember who) went to see US president Harry Truman and 
essentially told him that the scientists who developed the bomb should have a 
say of how or when it should be used.
Truman is reported to have said for him to leave his office and told an aid 
that was responsible for his schedule to "never in hell let that (or any other) 
scientist  come to his office to influence American defense policy."
Considering its status from both a scientific and political perspective, IMNSHO 
it will go on as before.
To explain the political. No government official wants to see China or the 
Russian federation tell the world quote: See, the USA can't be trusted for 
something as important and simple as frequency and time.  However we are your 
friends who you can trust. Unquote.
Regards,





This is a case of practical use of WWV albeit over 50 years a go the 
fundamentals are still valid today.
At Karamursel Air station TUSLOG 234 I was assigned to the base receiver site.  
Our base had to purposes.  to   




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Re: [time-nuts] NIST

[Scott McGrath]

WRT my sextant comment,   How many pilots or sailors can navigate by ‘shooting 
the sun/stars’.  They have become dependent on precision navigation systems.   

Which of course feeds the thinking by empty suits why do we need lighthouses, 
buoys, VOR’s and airway beacons because we have the ‘god box’ onboard.   Its 
old fashioned and uncool.

 Interestingly enough there have been enough GPS ‘outages’ that the USNO is 
once again requiring proficiency in celestial navigation in order to graduate 
food for thought there.

I was initially speaking about loss of GPS due to natural causes.   In times of 
international tension attacking a country by denying its ONLY source of 
precision time transfer would be a particularly effective tactic and you dont 
even have to damage the satellites themselves.   Just jam L1

As to relying on systems operated by one’s political adversaries that does not 
seem to be a wise option.

So once again for US’ians time to pick up the phone and put pen to paper and 
state while the US budget is bloated.   This particular item NEEDS to stay.   
Find a vanity construction project and make it disappear instead.   And point 
out the technical reasons it needs to stay.


Scott


On Aug 12, 2018, at 4:49 PM, Joe Dempster  wrote:

I hope that defunding is just a ploy and things will remain on the air.  I
am concerned this is starting to sound like 2010 when DHS/USCG took eLoran
off the air in the states.  This was one of the few things that totally
dismayed me about the Obama administration.

> On Sun, Aug 12, 2018 at 2:59 PM djl  wrote:
> 
> Just a word:   When budget cuts are announced, the agencies put the most
> valued "stuff" to be cut first, such as the Washington monument, etc.
> This is a recognized ploy. When the dust settles, all may be well. . .
> Don
> 
> 
>> On 2018-08-12 12:20, paul swed wrote:
>> Like all of you I have a few wwvb clocks that work pretty well here in
>> Boston.
>> Certainly have written enough wwvb stuff and created various wwvb
>> projects
>> that I will have to get back into it again.
>> I did look at the cron-verter. Have to say it has a lot of nice
>> features.
>> Unfortunately it hasn't been available for a year or so. (Getting lazy)
>> The good news is the AM modulation of wwb is very easy to create.
>> Regards
>> Paul
>> WB8TSL
>> 
>> On Sat, Aug 11, 2018 at 10:48 PM, Dana Whitlow 
>> wrote:
>> 
>>> I fear the worst.  The line in the website simply stated something
>>> like
>>> "shutting down
>>> the transmitters in Colorado and Hawaii", which would seem to include
>>> the
>>> whole
>>> enchilada.
>>> 
>>> For the wall clocks, GPS should work well if people are willing to go
>>> to
>>> battery-
>>> backed AC power.  But not so good for wristwatches, where the
>>> expectation
>>> is to
>>> run at uW power levels.  I for one would be very irritated at having
>>> to
>>> take my watch
>>> off my wrist and put it on a charging stand every night.  So if this
>>> shutdown comes
>>> to pass, I'll be looking for an inexpensive GPS-to-WWVB converter, or
>>> at
>>> least
>>> plans for building one.
>>> 
>>> Dana
>>> 
>>> 
>>> On Sat, Aug 11, 2018 at 8:12 PM, Bob Albert via time-nuts <
>>> time-nuts@lists.febo.com> wrote:
>>> 
 With any luck, the current administration will successfully push the
> USA
 down technically.  Denying global warming, shutting off time signals,
> and
 so on, is great stuff.
On Saturday, August 11, 2018, 6:10:12 PM PDT, Bob kb8tq <
>>> kb...@n1k.org>
 wrote:
 
 Hi
 
 One would *guess* that stopping WWVB (and killing mom and pop’s
> “atomic
 clocks”) would not be a reasonable thing to do.
 It gets a lot of voters mad. I doubt that very many voters (percentage
 wise) would notice WWV and WWVH going away ….
 
 Bob
 
> On Aug 11, 2018, at 9:00 PM, jimlux  wrote:
> 
> On 8/10/18 12:45 PM, Robert LaJeunesse wrote:
>> I'd say it does get more detailed, with the $49M in cuts described
 generally in groups here:
>> https://www.nist.gov/director/fy-2019-presidential-budget-
 request-summary/fundamental-measurement-quantum-science-and
>> One item: "-$6.3 million supporting fundamental measurement
 dissemination, including the shutdown of NIST radio stations in
> Colorado
 and Hawaii"
> 
> I wonder if that's WWVB, or WWV & WWVH
> 
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Re: [time-nuts] Loss of NIST transmitters at Colorado and Hawaii

[Scott McGrath]

This has ‘empty suit’ written all over it ,’move it to the $BUZZWORD 

Yes the LORAN shutdown was more impactful from a time transfer PoV but the NIST 
transmitters provide a crude backup and valuable scientific data with a long 
baseline

In NH we’ve had an unusually severe summer WRT weather events I normally have 
FIOS based 1gb internet connection which has now been down for 6 weeks.   It 
might be restored this week because new poles have been installed.

So Wife still has TV only because I maintained our satellite/Terrestrial system 
in readiness.

As for internet well I’m still running on a couple of Cradlepoint LTE gateways 
with yagi’s pointing at nearest tower and available bandwidth ranges from 100kb 
to 5mb with wild swings.

Putting all ones technical eggs in one basket is a bad idea from an operational 
and technical point of view.

What happens if a solar storm makes civillian GPS unavailable,   Hmm. Cell 
networks start going down as the GPSDO’s start drifting,  Kerberos 
authenticators begin to fail as wide area networks depending on GPS derived 
timing begin to drift (servers have CHEAP oscillators).

The rush to GPS based network timing is not a good idea,   We should be adding 
more wide area frequency sources not taking them away.

The NIST transmitters are very useful in calculating propagation and some sites 
have decades of data on this so its worth having them around for purely 
scientific reasons even though the technology of time and frequency transfer 
have moved forward.

Content by Scott
Typos by Siri

On Aug 12, 2018, at 9:55 PM, John C. Westmoreland, P.E. 
 wrote:

I hope this does not happen.  I get questions from new Hams that ask, 'How
can I check my antenna easily?' - the quick reply is to check for WWV on
2.5, 5,0, 10.0, 15.0 and 20.0 MHz.
Also, from my days in the Merchant Marine until now, I for one will truly
miss this service if it is discontinued, and this isn't the first time it
has some up.

I also tell new Hams - if you can understand the message from WWV that
gives out the number in Colorado - your antenna should be in pretty good
shape for HF (and or VHF/UHF at least to verify
it can receive ok).  At least it's an easy rule of thumb and an easy check
for most.

73's,
John
AJ6BC



> On Sun, Aug 12, 2018 at 6:46 PM, paul swed  wrote:
> 
> What bits I have read do seem to indicate its NIST that wants to cut the
> service. Since technology has moved beyond the services value which is kind
> of true. Just think what they can get for the land the sites on.
> Microsemi's comments were interesting in that in some manner there might be
> a NTP based solution that could be far more accurate then what we typically
> see today for NTP. But it also seemed to hint it would be a fee service. I
> think thats very very early.
> 
> Regards
> Paul
> WB8TSL
> 
> 
>> On Sun, Aug 12, 2018 at 8:37 PM, Wes  wrote:
>> 
>> Comment in the link about visiting WWV reminds me of my experience.  Many
>> years ago my late wife and I were roving around Colorado and I telephoned
>> WWV and asked if I could get a tour. I mentioned that I was a ham, an EE,
>> blah blah. This had worked before at other installations (not NAA
> however)
>> including the Apollo tracking station at Guaymas Mexico a day after a
>> splashdown.
>> 
>> The fellow I talked to was somewhat taken aback and said that they didn't
>> give tours.  I expressed some dismay and was about to hang up when he
> said,
>> "Actually, we have some contractors doing some work here and the gate is
>> unlocked.  If you were to come in you could look at the antennas, but
>> please stay in your car."  So we did.
>> 
>> Wes
>> 
>> 
>> 
>>> On 8/12/2018 4:05 PM, Bill Hawkins wrote:
>>> 
>>> 
>>> Group,
>>> 
>>> This subject needs some additional detail.  I found an article with
>>> comments at
>>> 
>>> https://swling.com/blog/2018/08/nist-fy2019-budget-includes-
>>> request-to-shutdown-wwv-and-wwvh/
>>> 
>> 
>> 
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Re: [time-nuts] Bicentennial GOES satellite clock

[Scott McGrath]

And with dependence on GPS we have created a serious vulnerability as too many 
critical pieces of infrastructure are dependent on a SINGLE precision timing 
and positioning system.

I can use a sextant and have a copy of Bowditch.But they only work on clear 
days and nights.

if GPS goes down for any reason.   Whats the backup solution?


On Aug 10, 2018, at 2:25 PM, Lester Veenstra  wrote:

Used to work with Wayne on two time transfer via satellite
Great guy


Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y
les...@veenstras.com

Physical and US Postal Addresses
5 Shrine Club Drive (Physical)
HC84 452 Stable Ln (RFD USPS Mail)
Keyser WV 26726
GPS: 39.336826 N  78.982287 W (Google)
GPS: 39.33682 N  78.9823741 W (GPSDO)


Telephones:
Home: +1-304-289-6057
US cell+1-304-790-9192 
Jamaica cell:   +1-876-456-8898 
 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Tom
Van Baak
Sent: Friday, August 10, 2018 10:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Bicentennial GOES satellite clock

Tim,

Thanks for posting that photo. That space age 1976 GOES clock caught our
eyes when the paper came out in 2005 (see also pages 11, 12, 13):

https://tf.nist.gov/general/pdf/2013.pdf

There was quite a bit of traffic on time-nuts around 2005 when the GOES
satellite time service was turned off (and back on, and off, and on, and
finally off for good). That left many of us with piles of 468 MHz GOES
receivers, antennae, clocks and led to efforts to re-create the RF signals
in-home so that GOES clocks would still work. There was even a commercial
G2G (GPS to GOES) translator.

Anyway, I asked around about that one-off bicentennial clock in the photo
and neither the authors, NIST, or Smithsonian knows where it ended up.
There's tons of information on the GOES satellite system and GOES clocks in
the NIST T archives:

https://tf.nist.gov/general/publications.htm

Best to search title for GOES, or search author for Hanson. It's a
fascinating glimpse into the recent past. Yes, it's sad that GOES (and
Omega, and Loran-C) aren't operational anymore, but GPS does such a better
job. Plus we now have cable, WiFi, cell phones, the internet, Iridium, etc.

If you wanted to build your own Bicentennial GOES Clock, the design was
published, including source code -- for its i4004 (!!) CPU. If you have even
one minute to spare, see attached image and click on these two PDF's:

"Satellite Controlled Digital Clock System (patent)"
https://tf.nist.gov/general/pdf/1791.pdf

"A Satellite-Controlled Digital Clock (NBS TN-681)"
https://tf.nist.gov/general/pdf/452.pdf

/tvb


- Original Message - 
From: "Tim Shoppa" 
To: "Discussion of precise time and frequency measurement"

Sent: Wednesday, August 08, 2018 7:29 PM
Subject: [time-nuts] Bicentennial GOES satellite clock


> See the groovy picture at
> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4847573/figure/f9-j110-2lom/
> 
> If anyone knows the whereabouts or history of the bicentennial GOES time
> clock display, please let me know!
> 
> Tim N3QE



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Re: [time-nuts] 10 MHz 'failover' switch?

[Scott McGrath]

True but if you use a good switch or PIN 90 db of isolation is easily 
achievable.   Yes the spur is still there but it’s 90 down and will not affect 
ADEV as badly.

You could drive it further down with two switches with the alternate standard 
connected to 1 port and a termination to the other.  So a switchover would 
switch to the alternate port and the backup path would switch from termination 
to backup source.This would easily buy you 120-130 db isolation assuming 
use of good cabling and proper routing, grounds etc

After all this IS time-nuts after all

Content by Scott
Typos by Siri

On Jul 26, 2018, at 6:23 PM, Van Horn, David 
 wrote:

Not quite what you are looking for, but I implemented a pair of thunderbolts 
with no common parts (dual antennas power etc) into a simple RF switch.
The production manager flipped the switch on Mondays, and if either system 
wasn't working I had a third system in a box ready to replace.
So for any failure of the two live systems, all he had to do was flip the 
switch and call me.


-Original Message-
From: time-nuts  On Behalf Of W7SLS
Sent: Thursday, July 26, 2018 1:46 PM
To: time-nuts@lists.febo.com
Subject: [time-nuts] 10 MHz 'failover' switch?

Hello,

Looking for recommendation for a ‘failover’ or ‘redundant’ switch for 10 MHz 
distribution.

   Not really sure of the correct term.
   Something that sensed RF on primary 10 MHz, and then switched to secondary 
on fail of primary.

A brief search showed several very nice $$$ items, suitable for commercial 
applications, but I wonder if there are some “last year’s” (but not last 
century) versions that would work for a home lab.

Context:

I have a GPSDO and a Rb source of 10 MHz.  
The power supply on the GPSDO failed (worked enough to light up the GPSDO, but 
not enough to lock).
I have a new power supply on order, but would be nice to have “insurance”.

Thanks in advance for the group bandwidth.

Scott
W7SLS
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Re: [time-nuts] 10 MHz 'failover' switch?

[Scott McGrath]

Build one yourself,   Detector diode on primary RF input when output drops use 
a rf relay or PIN diode switch to fail over to backup standard.All thats 
needed is a crossing detector and relay / switch driver

Yes there would be a momentary hit but it would work.

Content by Scott
Typos by Siri

On Jul 26, 2018, at 4:13 PM, Bob kb8tq  wrote:

Hi

They are a pretty rare item. A more common approach is a disciplined oscillator 
that 
will do failover on it’s inputs. That’s still a rare item, but at least a 
possible thing to find. 
The equally big problem will be getting doc’s on one if you do find it….

Bob

> On Jul 26, 2018, at 2:45 PM, W7SLS  wrote:
> 
> Hello,
> 
> Looking for recommendation for a ‘failover’ or ‘redundant’ switch for 10 MHz 
> distribution.
> 
>Not really sure of the correct term.
>Something that sensed RF on primary 10 MHz, and then switched to secondary 
> on fail of primary.
> 
> A brief search showed several very nice $$$ items, suitable for commercial 
> applications,
> but I wonder if there are some “last year’s” (but not last century) versions 
> that would work for a home lab.
> 
> Context:
> 
> I have a GPSDO and a Rb source of 10 MHz.  
> The power supply on the GPSDO failed (worked enough to light up the GPSDO, 
> but not enough to lock).
> I have a new power supply on order, but would be nice to have “insurance”.
> 
> Thanks in advance for the group bandwidth.
> 
> Scott
> W7SLS
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Re: [time-nuts] Need help machining an Aluminum cylinder

[Scott McGrath]

I can do it, on east coast though

Content by Scott
Typos by Siri

On Jul 12, 2018, at 6:13 PM, Rhys D  wrote:

If you get stuck, I can help. I am in New Zealand though, so postage may be
a concern.

On Fri, 13 Jul 2018 at 6:36 AM,  wrote:

> Hi,
> 
> I remember a few that had machine shops volunteering to help with
> machining last year but can't remember who!
> I have a 2 and 3/8" diameter cylinder 1.45" long.
> It needs nine  1/6" deep X 1/16" wide grooves machined in the
> circumference and adding some length to a slot already existing running
> down the side.
> This is to try another way to rebuild the HP 5065A Lamp oven.
> 
> Can anyone help?
> 
> Cheers,
> 
> Corby
> 
> 
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[time-nuts] DC-XL GPS STARTUP FIX

[Scott McGrath]

Does anyone recall off hand the GPS EPOCH startup fix for the DC-XL

I’m away from lab and notes trying to get one running for a friend.

As I recall it was on the order of func 12. F96  

But with these units you dont want to be entering random data via keypad

Content by Scott
Typos by Siri
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Re: [time-nuts] GPS Antenna Grounding/Lightning protection.

[Scott McGrath]

If you see St Elmos fire ‘corona discharge bleed process is working as expected

Content by Scott
Typos by Siri

On Jun 19, 2018, at 3:55 PM, Bob kb8tq  wrote:

Hi

If indeed a proper ground system *could* be depended on to “bleed off” and 
prevent discharge things
would be *much* simpler. Indeed I’ve been on towers and decided to exit that 
location as the bleed
process became audible. It very much does happen. It simply is not a 100% sort 
of thing.

Bob

> On Jun 19, 2018, at 12:01 PM, Scott McGrath  wrote:
> 
> Probably the easiest and most economical grounding system is the halo ground 
> with antenna grounds bonded to the halo and the house ground bonded to the 
> halo as well.
> 
> The halo conductor sizing is governed by local codes,   But really what you 
> are doing ensuring that the entire structure and earth around it is at the 
> same potential so a nearby strike does not cause ground currents to flow.
> 
> A direct strike is probably going to fry anything it hits because of the 
> gigajoules of energy concentrated within the discharge
> 
> But a proper ground system also ‘bleeds off’ the potential difference thereby 
> preventing discharge 
> 
> Content by Scott
> Typos by Siri
> 
> On Jun 19, 2018, at 11:19 AM, Bob kb8tq  wrote:
> 
> Hi
> 
> 18” down in a swamp likely is plenty for conductivity. 18” down in a sandy 
> desert (or on an ice sheet) may be way 
> short in terms of conductivity :) The real answer to any of this is “that 
> depends”. (Yes, the ice sheet grounding 
> problem is from a real case that shows up in some class notes from way back 
> ….).
> 
> Some locations get multiple  hits on a weekly basis in the summer. Other 
> locations get a close strike once every 
> few decades. What makes economic sense for one probably does not make sense 
> for the other…. A “full up” 
> protection setup can easily run into hundreds of thousands of dollars. I’d 
> much rather spend that kind of money
> on a Maser … or two …. or three :) …. this is TimeNuts after all ….
> 
> Bob
> 
> 
> 
>> On Jun 19, 2018, at 10:56 AM, Scott McGrath  wrote:
>> 
>> The 18” inch requirement is partially for damage resistance and partially to 
>> ensure adequate soil moisture for conductivity.   
>> 
>> Content by Scott
>> Typos by Siri
>> 
>> On Jun 19, 2018, at 10:50 AM, jimlux  wrote:
>> 
>> On 6/18/18 6:39 PM, Glenn Little WB4UIV wrote:
>> 
>>> To do the grounding correctly, all connections exterior to the building are 
>>> to be welded.
>>> The cable to ground rod welds are to be 18 inches below grade.
>>> The exterior cable is to be number 2 copper or larger.
>>> To bond numerous ground systems together, a number 2 copper cable is to be 
>>> buried at 18 inches and welded to each ground system.
>>> If using eight foot ground rods, a ground rod is to be driven every 16 feet 
>>> along the connecting cable and the cable welded to the rod.
>> 
>> 
>> It helps to know *why* some requirements exist - I suspect the 18" burial 
>> requirement is to avoid accidentally digging it up or damaging it. I can't 
>> think of an electrical reason for it.
>> 
>> 
>>> A lot of work, but, cheaper, in the long run, than continuing to 
>>> repair/replace equipment.
>> 
>> It depends
>> 
>> Unless you're doing geodetic or precision timing work with a 2 or 3 band 
>> GPS, replacement GPS antennas are cheap.
>> I'd worry about the receiver and related equipment, but the antenna itself 
>> might be sacrificial.
>> 
>> As always, there's a risk/budget tradeoff
>> 
>> 
>> 
>> 
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Re: [time-nuts] GPS Antenna Grounding/Lightning protection.

[Scott McGrath]

Probably the easiest and most economical grounding system is the halo ground 
with antenna grounds bonded to the halo and the house ground bonded to the halo 
as well.

The halo conductor sizing is governed by local codes,   But really what you are 
doing ensuring that the entire structure and earth around it is at the same 
potential so a nearby strike does not cause ground currents to flow.

A direct strike is probably going to fry anything it hits because of the 
gigajoules of energy concentrated within the discharge

But a proper ground system also ‘bleeds off’ the potential difference thereby 
preventing discharge 

Content by Scott
Typos by Siri

On Jun 19, 2018, at 11:19 AM, Bob kb8tq  wrote:

Hi

18” down in a swamp likely is plenty for conductivity. 18” down in a sandy 
desert (or on an ice sheet) may be way 
short in terms of conductivity :) The real answer to any of this is “that 
depends”. (Yes, the ice sheet grounding 
problem is from a real case that shows up in some class notes from way back ….).

Some locations get multiple  hits on a weekly basis in the summer. Other 
locations get a close strike once every 
few decades. What makes economic sense for one probably does not make sense for 
the other…. A “full up” 
protection setup can easily run into hundreds of thousands of dollars. I’d much 
rather spend that kind of money
on a Maser … or two …. or three :) …. this is TimeNuts after all ….

Bob



> On Jun 19, 2018, at 10:56 AM, Scott McGrath  wrote:
> 
> The 18” inch requirement is partially for damage resistance and partially to 
> ensure adequate soil moisture for conductivity.   
> 
> Content by Scott
> Typos by Siri
> 
> On Jun 19, 2018, at 10:50 AM, jimlux  wrote:
> 
> On 6/18/18 6:39 PM, Glenn Little WB4UIV wrote:
> 
>> To do the grounding correctly, all connections exterior to the building are 
>> to be welded.
>> The cable to ground rod welds are to be 18 inches below grade.
>> The exterior cable is to be number 2 copper or larger.
>> To bond numerous ground systems together, a number 2 copper cable is to be 
>> buried at 18 inches and welded to each ground system.
>> If using eight foot ground rods, a ground rod is to be driven every 16 feet 
>> along the connecting cable and the cable welded to the rod.
> 
> 
> It helps to know *why* some requirements exist - I suspect the 18" burial 
> requirement is to avoid accidentally digging it up or damaging it. I can't 
> think of an electrical reason for it.
> 
> 
>> A lot of work, but, cheaper, in the long run, than continuing to 
>> repair/replace equipment.
> 
> It depends
> 
> Unless you're doing geodetic or precision timing work with a 2 or 3 band GPS, 
> replacement GPS antennas are cheap.
> I'd worry about the receiver and related equipment, but the antenna itself 
> might be sacrificial.
> 
> As always, there's a risk/budget tradeoff
> 
> 
> 
> 
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Re: [time-nuts] GPS Antenna Grounding/Lightning protection.

[Scott McGrath]

The 18” inch requirement is partially for damage resistance and partially to 
ensure adequate soil moisture for conductivity.   

Content by Scott
Typos by Siri

On Jun 19, 2018, at 10:50 AM, jimlux  wrote:

On 6/18/18 6:39 PM, Glenn Little WB4UIV wrote:

> To do the grounding correctly, all connections exterior to the building are 
> to be welded.
> The cable to ground rod welds are to be 18 inches below grade.
> The exterior cable is to be number 2 copper or larger.
> To bond numerous ground systems together, a number 2 copper cable is to be 
> buried at 18 inches and welded to each ground system.
> If using eight foot ground rods, a ground rod is to be driven every 16 feet 
> along the connecting cable and the cable welded to the rod.


It helps to know *why* some requirements exist - I suspect the 18" burial 
requirement is to avoid accidentally digging it up or damaging it. I can't 
think of an electrical reason for it.


> A lot of work, but, cheaper, in the long run, than continuing to 
> repair/replace equipment.

It depends

Unless you're doing geodetic or precision timing work with a 2 or 3 band GPS, 
replacement GPS antennas are cheap.
I'd worry about the receiver and related equipment, but the antenna itself 
might be sacrificial.

As always, there's a risk/budget tradeoff




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Re: [time-nuts] GPS Antenna Grounding/Lightning protection.

[Scott McGrath]

Also see this

https://www.bicsi.org/uploadedfiles/bicsi_conferences/fall/2012/presentations/CONCSES_4C.pdf

Content by Scott
Typos by Siri

On Jun 18, 2018, at 5:51 PM, Charles Steinmetz  wrote:

Graham wrote:

> If you want to protect your installation from lightening, then there is a
> body of information that has been developed within the cellular industry
> that allows a properly installed cellular base site to take a direct hit
> and continue operating.
> 
> An example of what they do is documented in "Motorola R56 2005 manual.pdf"
> 
> Google that term to download the document.

Oz and Bill also provided good information.

PolyPhaser is the generally-accepted gold standard for lightning protection, 
and has many technical notes available.

Tisha Hayes has a big fat folder full of good stuff relating to "Grounding 
Surge and Filtering" at her dropbox site, and another one full of "Transient 
Protection Documents."  See:



Best regards,

Charles



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