[time-nuts] GPS antenna selection — lightning

[Hank Riley via time-nuts]

>From UL "Lightning Protection (2016):

"When we look at a Lightning Protection System in its most elementary form, it 
is quite simple. An air terminal(s) to attract and catch a lightning strike, a 
low resistance conducting cable that connects the air terminal to the earth 
using a conducting electrode and provide a pathway to dissipate the high energy 
into the earth. This system provides protection for the structure."
http://www.ul.com/wp-content/uploads/2014/04/LightningProtectionAG.pdf
So plain lightning rods do not operate to prevent strikes.

The notion that even various exotic spiny gizmos being marketed by a handful of 
companies, can, by dissipating charges or by other mechanisms, minimize or 
prevent lightning strikes to structures where they're installed has been 
discredited.  Or, to be conservative, the manufacturers' claims of 
lightning-prevention-by-charge dissipation devices have not been supported by 
real world tests.
There is a wealth of research in the literature on the subject of 
"unconventional methods" of lightning protection; this article from the 
Bulletin of the American Meteorological Society is a nice treatment and survey 
with many technical references.
http://www.lightningsafety.com/nlsi_lhm/Uman_Rakov.pdf
Hank




   

  
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Re: [time-nuts] Oscillator Phase Noise: A 50-Year Review

[Richard (Rick) Karlquist]

On 8/5/2016 12:47 PM, Tom Van Baak wrote:

Here's a new article, on IEEE's site (and this one's free):

"Oscillator Phase Noise: A 50-Year Review", by David B. Leeson
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7464875



It has always irked me that no credit was given to Edson's
pioneering 1953 book "Vacuum tube oscillators" in Leeson's papers
and I see that the omission continues in the latest paper.  You can see
from the following reference that Edson was the true pioneer in this
field:

http://garfield.library.upenn.edu/classics1983/A1983QV0081.pdf

He actually had the basic idea in 1934.  He is the proverbial
"unsung hero".

Rick
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[time-nuts] Venus838LPx-T preliminary testing

[Nick Sayer via time-nuts]

I got the first breakout boards back today. There’s an error on them I had to 
workaround, but having done that I was able to observe it getting first-fix 
(with good reception, TTFF is remarkably good, FWIW), then performing the 2000 
point survey and generating quantization error messages.

I’ve collected an hour’s worth of quantization error data (as reported by the 
unit) and attached it here, for those who wish to analyze it. It’s very, very 
jittery, but confined to a ±6 ns corridor. I was able to see what appeared to 
possibly be very, very brief hanging-bridge-like anomalies, but overall it 
looks just really noisy to me.

After the survey, the GGA position reported has not changed, which is as I’d 
expect. I don’t know if the unit periodically validates the position solution 
to insure it hasn’t been moved.

I don’t have matching PPS jitter data to go along with this. It’ll be 
interesting to attempt to correlate the two to get a picture of post-correction 
PPS stability, if I can.

I’m going to make a breakout board for these and list them on Tindie next week, 
for those who wish to play with them.

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Re: [time-nuts] GPS antenna selection — lightning

[Bob Camp]

Hi

Ummm ….. It’s a *lot* more fun to focus on the 0.001% case :)

Bob

> On Aug 5, 2016, at 9:31 PM, Chris Albertson  wrote:
> 
> You guys, well some of you are mixing to things
> 
> 1) the building code requirement to ground an antenna is for the protection
> of the building.  The building code don't care if you electronics is fried
> or not.   The wire and ground rod keep the antenna mast at earth potential.
> 
> 
> 2) Those surge protectors and grounding your electronics to a common point
> an al other advice then grounding the most to a rod by the nearest route
> down the side of the house.  These are different things
> 
> So, outdoor antenna are different from indoor antenna in that if you indoor
> antenna is struck the house is already pretty much toasted.   You still
> might want a surge protector to protect the receiver.
> 
> The question is if you need to buy a $40 surge protector for your $8
> Motorola Encore receiver?  But no question if you need a group wire in the
> mast, even for that $8 gps receiver because that wire protects the house
> 
> Part of the equation is where you live.  In many years of living in Redondo
> Beach, CA I never hear of anyone or anything being =damaged by lightening.
> We don't even get lighting here but twice a year if that.   On the other
> hand I had god protection on my sailboat as that 60 for aluminum mast might
> be the highest thing around on the ocean for miles.  That mast has a very
> solid connection straight to saltwater.  You have to evaluate the risk and
> consequence.  You get different answer in Orlando Florida then I get here.
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Re: [time-nuts] GPS antenna selection — lightning

[Glenn Little WB4UIV]

A very good reference for EMP protection is MIL-HDBK-419.
This is downloadable for a number of web sources.
It is about 600 pages and is in two volumes.
This discusses a number of different sources of EMP such as nuclear and 
lightning.
A lot is for protection of military industrial complexes, but, there is 
a lot that pertains to us.


I worked for a military complex that assembled nuclear missiles.
The site was built to this handbook specs.
We had no EMP related damage at the site.

Number one rule, bond all grounds together. If something on your 
property takes a hit, you want everything on your property to elevate to 
the same level and the same rate.
If you have multiple, non bonded grounds, there is a different reference 
for each ground. This is a major source for disaster.


I spent seven years in lightning mitigation. I was told by professionals 
that I was wrong. The third time that their tower was struck, destroying 
all of the lights and attached equipment, they followed my 
recommendations. That was ten years ago. The three hits were within four 
months of each other. The site has been free of destructive hits since then.


73
Glenn
WB4UIV



On 8/5/2016 10:37 AM, Eric Scace wrote:

Unfortunately, an antenna, cable, or piece of electronics located indoors is 
just as susceptible to lightning surges as one that is outdoors.

Lightning-induced surges couple into these systems electromagnetically across a 
wide range (VLF to SHF) of frequencies. When you think about your home from an 
electromagnetic viewpoint, just imagine your structure with all non-conductive 
materials absent. For a typical wood or brick/stone house in North America, 
what you are left with is:
metal plumbing pipes and fixtures, with their geometry suspended in space
house wiring, CATV, Ethernet, and telephone cabling, and their service drops, 
all suspended in space
electrical & electronic circuits of every kind (WiFi note, computer, 
appliances), their power supplies and AC power cords, also suspended in space
metal furniture? That’s hanging out there, suspended in space, too.
any I-beam or other steel structural elements, some random aluminum flashing, 
door knobs, and other similar metal construction materials used in the home.
That is what an electromagnetic pulse sees as it approaches and sweeps over 
your home… all hovering over a lossy ground plane (earth) its varying 
dielectric constant.. Each one of those pieces of metal, hanging in space, is 
an unintentional antenna that experiences voltage differentials and current 
flows.

A GPS antenna and its coax line that is installed next to a window is no 
different from the same antenna/coax installed one meter outside the window… or 
10 meters away outside the window. All three installations are effectively 
“outdoors” from an electromagnetic viewpoint, and all three need effective 
surge protection from lightning-, cloud-, and precipitation-induced voltage 
surges.

(N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands of 
volts per meter potential differences in moderate-to-heavy snowfall that 
produced very significant current flows on cables.)

Surge protection for your antenna, its attachment to your receiver(s), AC/DC 
power supply lines, and any other signal lines of significant length is cheap 
insurance.

My continuously-operating electronics lives in an enclosed rack cabinet — not 
too much worse than a proper Faraday cage. Every cable entering the cabinet has 
surge protection at the point of entry. The cabinet is bonded to earth ground 
by 2” copper flashing. In the past this system lived 22 years on a mountaintop 
home, 1200 ft above surrounding terrain. Lots of thunderstorms — zero 
damage/disruptions during that time… a sample size of one, admittedly, but 
during the first 18 months at that site I had two lightning-surge damaging 
events before I got serious about protection.

I have equipment at a coastal site with multiple 130-ft towers. That site had 
damage events every 2 years or so — even when cables to the “outside” were 
disconnected, and AC mains power was shut off at the main circuit breaker box. 
After implementing comprehensive surge protection, we have had zero damage over 
the last 12 years.

— Eric


On 2016 Aug 04, at 19:46 , Bob Camp  wrote:


Grounding the antenna is always a good idea.



A surge suppressor in the line could save you some
real cost if there is a lightning strike.


I did a quick search for SMA/BNC/TNC based surge
protectors and not much did come up, any suggestions
what to use there?


There are a *lot* of them on eBay. Many of them have N connectors on them.




I don’t know about Austria, but here in the US,
both are required.


Outside definitely, "inside" I'm not sure, but it
won't hurt to have additional protection for the
receiver(s).


It is a good bet that the antenna will be outside. I’d plan it that way.




___
time-nuts 

Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Alexander Pummer]

Meinberg https://www.meinbergglobal.com/ makes complete down and up 
converter for GPS remote antennas


73
KJ6UHN
Alex

On 8/5/2016 3:11 PM, Rick Jones wrote:

On 08/04/2016 06:02 PM, Hal Murray wrote:


rick.jon...@hpe.com said:
HalM was kind enough to come over the other day with some antennae 
which  we

tried without success.


I was going to suggest taking the cover off and looking inside but it 
fell

off my to-do list.

GPS receivers are reasonably specialized.  I doubt it anybody makes one
targeted at the down-converter market.

Is there an up-converter in there feeding a normal receiver?  If so, 
it might

be possible/easy to bypass.

If it looks like a direct connection to a normal receiver, I'd guess 
it has
special firmware.  It might be possible to replace it with one with 
normal

firmware.


My peanut gallery level of knowledge means I wouldn't recognize a 
normal receiver if it reared up and, well, you know :)


I do though have some pictures of the relevant section of the machine 
with the cover off - two of the same shot at:


ftp://ftp.netperf.org/dc-xl

The antenna connection is the silver "square" on the left.  There are, 
as you can see, a number of jumpers everywhere.  The daughter card is 
connected at its "top left" in the picture where those "5s" of posts 
are.  There are some shiny gold (plated?) posts there underneath them, 
and a couple other vertical connections more towards the center.


That entire assembly can slide out of the chassis after removing four 
screws at the back.  I didn't try to remove the daughter card.


rick jones

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Re: [time-nuts] GPS antenna selection — lightning

[Chris Albertson]

You guys, well some of you are mixing to things

1) the building code requirement to ground an antenna is for the protection
of the building.  The building code don't care if you electronics is fried
or not.   The wire and ground rod keep the antenna mast at earth potential.


2) Those surge protectors and grounding your electronics to a common point
an al other advice then grounding the most to a rod by the nearest route
down the side of the house.  These are different things

So, outdoor antenna are different from indoor antenna in that if you indoor
antenna is struck the house is already pretty much toasted.   You still
might want a surge protector to protect the receiver.

The question is if you need to buy a $40 surge protector for your $8
Motorola Encore receiver?  But no question if you need a group wire in the
mast, even for that $8 gps receiver because that wire protects the house

Part of the equation is where you live.  In many years of living in Redondo
Beach, CA I never hear of anyone or anything being =damaged by lightening.
We don't even get lighting here but twice a year if that.   On the other
hand I had god protection on my sailboat as that 60 for aluminum mast might
be the highest thing around on the ocean for miles.  That mast has a very
solid connection straight to saltwater.  You have to evaluate the risk and
consequence.  You get different answer in Orlando Florida then I get here.
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Re: [time-nuts] GPS antenna selection

[Tom Van Baak]

Herbert Poetzl wrote:
> I'm currently investigating my options regarding 
> GPS antennae (of course for time related purposes)
> and I'm really confused by the variety they come
> in ... (my apologies in advance for the long post).

Yes, lots of variety! See: http://leapsecond.com/museum/gps-ant/

/tvb
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Re: [time-nuts] GPS antenna selection — lightning

[Alexander Pummer]

lightening protection:

http://www.ul.com/wp-content/uploads/2014/04/LightningProtectionAG.pdf

73
KJ6UHN
Alex

On 8/5/2016 1:51 PM, Attila Kinali wrote:

Hi Eric,

On Fri, 5 Aug 2016 10:37:28 -0400
Eric Scace  wrote:


A GPS antenna and its coax line that is installed next to a window is no
different from the same antenna/coax installed one meter outside the window…
or 10 meters away outside the window. All three installations are
effectively “outdoors” from an electromagnetic viewpoint, and all three need
effective surge protection from lightning-, cloud-, and precipitation-
induced voltage surges.

Please please please do NOT spread dangerous information like this!

While it is true, that an indoor antenna is suceptible to surges like
an outdoor antenna, it is not true that an outdoor antenna is equivalent
to an indoor antenna when it comes to lightning protection.

Because an outdoor antenna can be _directly_ hit by a lightning.

To protect the house and its inhabitants from the lightning strike,
an external antenna needs to be either lower than any lightning rod
and within its 45m ball or needs its own conductor and grounding
to discharge any lightning energy and thus preventing it from following
the antenna cable into the house.

Please be aware that the grounding of the antenna is not to protect
the equipment from surges, but to prevent conduction of the lightning
into the house that could cause electrocution and fires.

Attila Kinali



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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Michael Wouters]

On Sat, Aug 6, 2016 at 6:41 AM, Attila Kinali  wrote:

> So, best you can hope for is an jitter of ~50us rms within the same
> city with _good_ network connections. Once the distance increases
> and especially if you get routers with conquestion inbetween, then
> the delay and its jitter rise quickly.

That pretty well agrees with my practical experience of NTP on
somewhat longer, uncongested links.
NTP servers separated physically by 1000-3000 km but perhaps 10
network hops had apparent offsets of about 100 us rms with respect to
each other.

Cheers
Michael

On Sat, Aug 6, 2016 at 6:41 AM, Attila Kinali  wrote:
> On Fri, 5 Aug 2016 21:35:05 +0200
> Magnus Danielson  wrote:
>
>> > From a "Time Nuts" point of view none of the above are even close to
>> > accurate clocks.  A microsecond is a very course and crude measure of
>> > time.  Pico and Femto seconds are were it gets interesting.
>>
>> Certainly. Look at White Rabbit, which really changes how PTP works.
>> It may not be pico second accurate, but you get pretty far with it.
>
> WR achieves sub-ns accuracy. Depending on the environment <200ps offset/skew
> are possible.
>
>> > Maybe someday NTP will have a time nuts level of accuracy.  the new up
>> > coming version, I hear will be using 64 bits to carry the factional part of
>> > a second.  That is truly nuts.
>>
>> Well, if NTP takes the main ideas from PTP and White Rabbit, maybe then.
>
> This wont help. The achievable accuracy is dictated by the measurement
> and the delay uncertainty. Even with network cards that support time stamping,
> you cannot hope to get better than 1/125MHz=8ns. Standard network cards
> will just trigger an IRQ at some point after reception and enqueuing of
> the packet. The IRQ is measured by the OS, which leads to uncertainties
> in the order of several us to a couple of 10s of us. If the card does DMA
> the packet directly into main memory, then this value is even more inflated.
>
> The network itself has a relatively high jitter. Assume 10s to 100s of us
> on a local network per switch. Once you pass a router, you can assume
> jitter in the order of a couple of 100us to a couple of ms per router.
>
> To illustrate this, here a few ping statistics (64byte, 1000 packets each):
>
> Local network, GBit/s, two level1 smart switches:
> rtt min/avg/max/mdev = 0.073/0.131/0.362/0.044 ms
>
> Two hosts in colo centers within the same city, same ISP, hence
> on the same "network" (ie no conguestion), 4 hops:
> rtt min/avg/max/mdev = 0.288/0.437/0.620/0.051 ms
>
> Two hosts in colo centers, within the same city, different ISP
> but with direct peering (ie no conguestion), 9 hops:
> rtt min/avg/max/mdev = 2.916/3.008/3.505/0.078 ms
>
> Two hosts in colo centers, one in Switzerland, one in Germany, 9 hops
> rtt min/avg/max/mdev = 12.636/12.947/28.943/0.609 ms
>
> These are all well connected machines, with "carrier grade" networks
> inbetween. No consumer internet connections with their huge delays
> and jitter.
>
> So, best you can hope for is an jitter of ~50us rms within the same
> city with _good_ network connections. Once the distance increases
> and especially if you get routers with conquestion inbetween, then
> the delay and its jitter rise quickly.
>
>
> Attila Kinali
>
> --
> Malek's Law:
> Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] GPS antenna selection — lightning

[new]

Flying a plane with a plexiglas windshield through a snowstorm will give 
you a lightning show on your windshield.


Willy


On 8/5/2016 10:37 AM, Eric Scace wrote:

Unfortunately, an antenna, cable, or piece of electronics located indoors is 
just as susceptible to lightning surges as one that is outdoors.

Lightning-induced surges couple into these systems electromagnetically across a 
wide range (VLF to SHF) of frequencies. When you think about your home from an 
electromagnetic viewpoint, just imagine your structure with all non-conductive 
materials absent. For a typical wood or brick/stone house in North America, 
what you are left with is:
metal plumbing pipes and fixtures, with their geometry suspended in space
house wiring, CATV, Ethernet, and telephone cabling, and their service drops, 
all suspended in space
electrical & electronic circuits of every kind (WiFi note, computer, 
appliances), their power supplies and AC power cords, also suspended in space
metal furniture? That’s hanging out there, suspended in space, too.
any I-beam or other steel structural elements, some random aluminum flashing, 
door knobs, and other similar metal construction materials used in the home.
That is what an electromagnetic pulse sees as it approaches and sweeps over 
your home… all hovering over a lossy ground plane (earth) its varying 
dielectric constant.. Each one of those pieces of metal, hanging in space, is 
an unintentional antenna that experiences voltage differentials and current 
flows.

A GPS antenna and its coax line that is installed next to a window is no 
different from the same antenna/coax installed one meter outside the window… or 
10 meters away outside the window. All three installations are effectively 
“outdoors” from an electromagnetic viewpoint, and all three need effective 
surge protection from lightning-, cloud-, and precipitation-induced voltage 
surges.

(N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands of 
volts per meter potential differences in moderate-to-heavy snowfall that 
produced very significant current flows on cables.)

Surge protection for your antenna, its attachment to your receiver(s), AC/DC 
power supply lines, and any other signal lines of significant length is cheap 
insurance.

My continuously-operating electronics lives in an enclosed rack cabinet — not 
too much worse than a proper Faraday cage. Every cable entering the cabinet has 
surge protection at the point of entry. The cabinet is bonded to earth ground 
by 2” copper flashing. In the past this system lived 22 years on a mountaintop 
home, 1200 ft above surrounding terrain. Lots of thunderstorms — zero 
damage/disruptions during that time… a sample size of one, admittedly, but 
during the first 18 months at that site I had two lightning-surge damaging 
events before I got serious about protection.

I have equipment at a coastal site with multiple 130-ft towers. That site had 
damage events every 2 years or so — even when cables to the “outside” were 
disconnected, and AC mains power was shut off at the main circuit breaker box. 
After implementing comprehensive surge protection, we have had zero damage over 
the last 12 years.

— Eric


On 2016 Aug 04, at 19:46 , Bob Camp  wrote:


Grounding the antenna is always a good idea.
A surge suppressor in the line could save you some
real cost if there is a lightning strike.

I did a quick search for SMA/BNC/TNC based surge
protectors and not much did come up, any suggestions
what to use there?

There are a *lot* of them on eBay. Many of them have N connectors on them.


I don’t know about Austria, but here in the US,
both are required.

Outside definitely, "inside" I'm not sure, but it
won't hurt to have additional protection for the
receiver(s).

It is a good bet that the antenna will be outside. I’d plan it that way.



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Re: [time-nuts] Oscillator Phase Noise: A 50-Year Review

[KA2WEU--- via time-nuts]

Some of the cited references are poor, modern non-linear mathematic is kind 
 of omitted . After all the oscillator  phase noise speculation, I would  
have really liked to see at last a reference about the most modern 
measurements  techniques and it validation. How do you calibrate a phase noise 
test  
system.
 
Leeson produced a somewhat random selection of papers , omitting important  
things like the sapphire based best in the word . This was not even 
referenced  .
 
I think he is really out of it .
 
73 de N1UL  
 
 
 
In a message dated 8/5/2016 7:11:18 P.M. Eastern Daylight Time,  
j...@miles.io writes:

>  
> Very selected and incomplete references and the equally   important
> question
> of measurements strangely not  covered
> 
> 73 de N 1  UL
> 

I suppose he could  write an equally-lengthy article on measurements alone, 
but leaving out the  post-1970s history entirely was a little 
disappointing.  It was strange  to hit "ctrl-f Rohde" and see only one 
reference in the 
bibliography.   Same for "Hewlett."  "Rubiola" brings up one hit (but no 
citations) and  "Stein" brings up none at all.  

-- john, KE5FX
Miles Design  LLC


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Re: [time-nuts] Looking to find an antenna for a TrueTime XL-DC

[Rick Jones]

On 08/04/2016 06:02 PM, Hal Murray wrote:


rick.jon...@hpe.com said:

HalM was kind enough to come over the other day with some antennae which  we
tried without success.


I was going to suggest taking the cover off and looking inside but it fell
off my to-do list.

GPS receivers are reasonably specialized.  I doubt it anybody makes one
targeted at the down-converter market.

Is there an up-converter in there feeding a normal receiver?  If so, it might
be possible/easy to bypass.

If it looks like a direct connection to a normal receiver, I'd guess it has
special firmware.  It might be possible to replace it with one with normal
firmware.


My peanut gallery level of knowledge means I wouldn't recognize a normal 
receiver if it reared up and, well, you know :)


I do though have some pictures of the relevant section of the machine 
with the cover off - two of the same shot at:


ftp://ftp.netperf.org/dc-xl

The antenna connection is the silver "square" on the left.  There are, 
as you can see, a number of jumpers everywhere.  The daughter card is 
connected at its "top left" in the picture where those "5s" of posts 
are.  There are some shiny gold (plated?) posts there underneath them, 
and a couple other vertical connections more towards the center.


That entire assembly can slide out of the chassis after removing four 
screws at the back.  I didn't try to remove the daughter card.


rick jones

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Re: [time-nuts] Oscillator Phase Noise: A 50-Year Review

[John Miles]

> 
> Very selected and incomplete references and the equally  important
> question
> of measurements strangely not covered
> 
> 73 de N 1  UL
> 

I suppose he could write an equally-lengthy article on measurements alone, but 
leaving out the post-1970s history entirely was a little disappointing.  It was 
strange to hit "ctrl-f Rohde" and see only one reference in the bibliography.  
Same for "Hewlett."  "Rubiola" brings up one hit (but no citations) and "Stein" 
brings up none at all.  

-- john, KE5FX
Miles Design LLC


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Re: [time-nuts] GPS antenna selection — lightning

[Gary E. Miller]

Yo Attila!

On Fri, 5 Aug 2016 22:51:06 +0200
Attila Kinali  wrote:

> While it is true, that an indoor antenna is suceptible to surges like
> an outdoor antenna, it is not true that an outdoor antenna is
> equivalent to an indoor antenna when it comes to lightning
> protection. 

I agree there are differences.  But not as mmuch as you think.

> Because an outdoor antenna can be _directly_ hit by a lightning.

And so can an indoor antetnna.  I live it lightning country, and it is
common for a lightning bolt to travel right through an asphalt roof to
hit metal pipes and/or wire inside a house.

I have seen this many times, it has happened to my next door neighbor and
to my son.  If you are lucky your homeowners insurance will cover a lot of
the damage.

> Please be aware that the grounding of the antenna is not to protect
> the equipment from surges, but to prevent conduction of the lightning
> into the house that could cause electrocution and fires. 

A direct hit on an antenna will laugh at your surge protector.  Nothing
at all can protect your electrical system from a direct hit.

I have seen 440V main switchboards exploded from lightning hits.  The
mess is incredible.  The switchboard case looks like a large bomb went off
inside and the cover leaves a dent on the far wall.

The surge protector on your antenna coax will try to limit the static
voltage on the center conductor to about 1,500V.  Now you have turned
your antenna into a passable lightning rod.

> To protect the house and its inhabitants from the lightning strike,
> an external antenna needs to be either lower than any lightning rod
> and within its 45m ball or needs its own conductor and grounding
> to discharge any lightning energy and thus preventing it from following
> the antenna cable into the house.

If you have any doubt about lightning you need to get some lightning rods
on your roof.  A usually passable solution is to run #8 wire from your
offical building ground directly up to an antenna mast or two on your
roof.  Best if it can be done with zero splices.

The point of the lightning rod is not to dissipate a lightning strike,
nothing can do that.  Instead it bleeds away static before it becomes
a lightning strike.

In the midwest in the winter the humidity in a house can get well below
5% and 1,500V of statis is quite common.  So indoor surge protectors
can also be useful.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Bob Camp]

Hi

Ok, here I am at home. My network gear is simple. Cisco low end switches and 
Gig-E wires. 
No fancy Sync-E. No 1588 stamps from the switches. Data comes in via a cable 
modem. The
beast has highly asymmetric send and receive transit times. They both wander 
around in 
response to their own gods. 

These limits are not at all unusual. In fact, the Gig-E probably is more stable 
than the WiFi 
that some people now consider to be the standard approach to home networking. 
My cable
modem is not at all unusual in it’s design or performance. There are a *lot* of 
businesses out
there with worse issues than what I have here. 

If I call up my cable guy and ask about Sync-E or 1588 stamps they actually are 
smart enough
(or Bob’s calls get routed specifically …) to tell me I’m nuts and carefully 
explain why. The unusual
part there is the care rather than me being nuts to ask for that sort of stuff 
on my external 
connection. 

This all pretty quickly gets one back to an NTP-like approach. All of the “cool 
new stuff” in hardware
isn’t going to do me much good. I go looking for 1588 gear and my switch budget 
starts to look
like the price of a nice new BMW. That isn’t going to happen (the switches or 
the BMW). Someday 
maybe 1588 will become “normal”. That hasn’t happened yet. The early 
predictions of it being 
universal in the next generation of switches died several generations ago. 

In terms of the question “how do I keep my PC at the right time?” …. the 
solutions are all pretty basic
due to the lack of fancy network time transfer support. 

Bob

> On Aug 5, 2016, at 3:35 PM, Magnus Danielson  
> wrote:
> 
> Chris,
> 
> On 08/05/2016 03:39 AM, Chris Albertson wrote:
>> I always wonder why people try all kinds of solutions when there are two
>> known to work as well as theoretically possible.
>> 
>> There is NTP and PTP.
>> 
>> NTP was released to the world in 1985, about 30 years ago.  The algorithm
>> has been in peer reviewed papers and the source code gets reviewed
>> continuously by experts in the field and when one of them finds a problem
>> solutions are discussed and corrections are made.  After 30 years of
>> continuous review and revision it is close to as good as it will get.
>> (except for possible security issues in the implementation)  There is a
>> very active community of academics and computer scientists that keep NTP up
>> to date.Its problem is that it is designed to work over a public
>> network that the user has no control over so the assumption must be made
>> that the network equipment has only some minimum features.  NTP's accuracy
>> tops out (with great effort) at about 1 microsecond but typically 1
>> millisecond
> 
> With essentially the same messages, but altered rules better performance can 
> most likely be achieved in NTP. I'm not at all convinced that several of the 
> assumptions in NTP is very useful or valid.
> 
>> PTP on the other hand is designed to do about the same as NTP but over a
>> local network the user has complete control over and requires specialized
>> networking equipment.  PTP accuracy routinely breaks 1uSec but can't work
>> so well over a public Internet.
>> 
>> If these two where not free, easy to set up and well supported then it
>> might be worth looking for something else.
> 
> It is worth looking for something else, because each have their technological 
> and practical limits.
> 
>> From a "Time Nuts" point of view none of the above are even close to
>> accurate clocks.  A microsecond is a very course and crude measure of
>> time.  Pico and Femto seconds are were it gets interesting.
> 
> Certainly. Look at White Rabbit, which really changes how PTP works.
> It may not be pico second accurate, but you get pretty far with it.
> 
>> Maybe someday NTP will have a time nuts level of accuracy.  the new up
>> coming version, I hear will be using 64 bits to carry the factional part of
>> a second.  That is truly nuts.
> 
> Well, if NTP takes the main ideas from PTP and White Rabbit, maybe then.
> 
> PTP adds hardware time-stamping and attempts to compensate one-way delays 
> that otherwise eats precision for breakfast.
> 
> White rabbit attempts much higher resolution while doing it, adding high 
> resolution measures and Synchronous Ethernet into the mix, letting PTP be 
> relatively time-insensitive message vehicle.
> 
>> Yes, there is room for more software if maybe one needs to transform time
>> under conditions not covered by NTP or PTP or needs to do much better than
>> 1uSec.  But typically when that happens we resort to hardware solutions
>> like 1PPS distributions and/or 10MHz distortions or common view of GPS
>> carriers signals.  Packetized network just don't work if you need to be
>> much better than 1uSec.
> 
> Slowly pushing down there, but there is a lot of things to care about, and 
> tradition to break with.
> 
> NTP might work nicely for you, PTP might help you too, but you can do better 
> in several 

Re: [time-nuts] Oscillator Phase Noise: A 50-Year Review

[KA2WEU--- via time-nuts]

This is in reference to 
 
Here's a new article, on IEEE's site (and this one's  free):

"Oscillator Phase Noise: A 50-Year  Review", by David B.  Leeson
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7464875



In a message dated 8/5/2016 4:48:59 P.M. Eastern Daylight Time,  
ka2...@aol.com writes:

Very selected and incomplete references and the equally  important question 
of measurements strangely not covered

73 de N 1  UL

Sent from my iPhone

> On Aug 5, 2016, at 3:47 PM,  "Tom Van Baak"  wrote:
> 
> Here's a new  article, on IEEE's site (and this one's free):
> 
> "Oscillator  Phase Noise: A 50-Year Review", by David B. Leeson
>  http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7464875
> 
>  
> 
> Also, a few months IEEE had a "Special Issue to  celebrate the 50th 
anniversary of the Allan Variance".
> The full list  of papers is here:
>  http://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=7445917
> 
>  Most of the articles are behind the IEEE paywall. Some free exceptions  
here:
> 
> "Introduction to the Special Issue on Celebrating the  50th Anniversary 
of the Allan Variance"
>  http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7445935
> 
>  "The Parabolic Variance (PVAR): A Wavelet Variance Based on the 
Least-Square  Fit"
>  http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7323846
> also  at:
> http://arxiv.org/pdf/1506.00687.pdf
> 
> "Simulations  of the Hadamard Variance: Probability Distributions and 
Confidence  Intervals"
>  http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7350241
> 
>  
> 
> Best of all, a free version of the David Allan and Judah  Levine paper is 
here:
> 
> "A Historical Perspective on the  Development of the Allan Variances and 
Their Strengths and Weaknesses"
>  http://tf.boulder.nist.gov/general/pdf/2834.pdf
> 
> /tvb
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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Rick Jones]

On 08/05/2016 01:41 PM, Attila Kinali wrote:

Standard network cards will just trigger an IRQ at some point after
reception and enqueuing of the packet.


Perhaps drifting a bit...

In the broadest of handwaving terms, prior to Gigabit Ethernet, NICs 
(Ethernet anyway) would post an interrupt for each arriving frame.  In 
the 100 Mbit/s Ethernet cards, (and perhaps FDDI and others) they 
started avoiding transmit completion interrupts.  With gigabit Ethernet, 
they started avoiding receive interrupts through interrupt coalescing 
settings.  Different NICs did/do it differently, and some better than 
others.  Under Linux at least, one can use the ethtool utility to tweak 
or even disable interrupt coalescing.  That would likely be Just Fine 
(tm) for a system dedicated to timekeeping, but the performance effects 
on "normal" networking might be more than one desired.


With 10 Gigabit NICs, multiple receive queues come into play (again, 
handwaving a bit).  I would think that some of the later ones would be 
sophisticated enough to enable sending NTP traffic through a specific 
queue/IRQ but I don't know of any 10 GbE NICs with per-queue coalescing 
settings.  My experience with 10 Gbit/s NICs and the likes of say a 
netperf TCP_RR test has been that except perhaps for the worst of them, 
they will not arbitrarily delay a packet arriving at an "idle" time.


What *will* be a non-trivial bummer for such things as a netperf TCP_RR 
test (think ping without "think time") will be power management in the 
processor(s).  Perhaps not visible in a MAN/WAN test setup, but 
certainly visible in a LAN one.


rick jones
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Re: [time-nuts] GPS antenna selection — lightning

[Attila Kinali]

Hi Eric,

On Fri, 5 Aug 2016 10:37:28 -0400
Eric Scace  wrote:

> A GPS antenna and its coax line that is installed next to a window is no 
> different from the same antenna/coax installed one meter outside the window… 
> or 10 meters away outside the window. All three installations are 
> effectively “outdoors” from an electromagnetic viewpoint, and all three need 
> effective surge protection from lightning-, cloud-, and precipitation-
> induced voltage surges.

Please please please do NOT spread dangerous information like this!

While it is true, that an indoor antenna is suceptible to surges like
an outdoor antenna, it is not true that an outdoor antenna is equivalent
to an indoor antenna when it comes to lightning protection. 

Because an outdoor antenna can be _directly_ hit by a lightning.

To protect the house and its inhabitants from the lightning strike,
an external antenna needs to be either lower than any lightning rod
and within its 45m ball or needs its own conductor and grounding
to discharge any lightning energy and thus preventing it from following
the antenna cable into the house.

Please be aware that the grounding of the antenna is not to protect
the equipment from surges, but to prevent conduction of the lightning
into the house that could cause electrocution and fires. 

Attila Kinali

-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Scott McGrath]

Because people have been trained by marketeers to look for the 'silver bullet'  
 But there are generally only a few methods to accomplish a given task 

Heck look at the 'cloud' those of us who were using large scale computers in 
the 80's called it 'timesharing'  and the most important app on the PC at the 
time was a vt100 or 3270 emulator and graphics were done on a Tek vector 
terminal

Content by Scott
Typos by Siri

> On Aug 4, 2016, at 9:39 PM, Chris Albertson  wrote:
> 
> I always wonder why people try all kinds of solutions when there are two
> known to work as well as theoretically possible.
> 
> There is NTP and PTP.
> 
> NTP was released to the world in 1985, about 30 years ago.  The algorithm
> has been in peer reviewed papers and the source code gets reviewed
> continuously by experts in the field and when one of them finds a problem
> solutions are discussed and corrections are made.  After 30 years of
> continuous review and revision it is close to as good as it will get.
> (except for possible security issues in the implementation)  There is a
> very active community of academics and computer scientists that keep NTP up
> to date.Its problem is that it is designed to work over a public
> network that the user has no control over so the assumption must be made
> that the network equipment has only some minimum features.  NTP's accuracy
> tops out (with great effort) at about 1 microsecond but typically 1
> millisecond
> 
> PTP on the other hand is designed to do about the same as NTP but over a
> local network the user has complete control over and requires specialized
> networking equipment.  PTP accuracy routinely breaks 1uSec but can't work
> so well over a public Internet.
> 
> If these two where not free, easy to set up and well supported then it
> might be worth looking for something else.
> 
> From a "Time Nuts" point of view none of the above are even close to
> accurate clocks.  A microsecond is a very course and crude measure of
> time.  Pico and Femto seconds are were it gets interesting.
> 
> Maybe someday NTP will have a time nuts level of accuracy.  the new up
> coming version, I hear will be using 64 bits to carry the factional part of
> a second.  That is truly nuts.
> 
> Yes, there is room for more software if maybe one needs to transform time
> under conditions not covered by NTP or PTP or needs to do much better than
> 1uSec.  But typically when that happens we resort to hardware solutions
> like 1PPS distributions and/or 10MHz distortions or common view of GPS
> carriers signals.  Packetized network just don't work if you need to be
> much better than 1uSec.
> 
>> On Thu, Aug 4, 2016 at 11:47 AM, David  wrote:
>> 
>> The old Tardis program for Windows (Tardis2000 now) handles it
>> correctly by altering the rate and only jamming the time if it is
>> outside of a specified window but I do not think its GPS mode supports
>> the 1 PPS signal.
>> 
>> I am not sure if Tardis works with Windows 7 and above though; I
>> forget to test it on my Windows 7 test system when I had it.  It is a
>> pretty old (but free) program.
>> 
>>> On Tue, 2 Aug 2016 23:28:06 -0700, you wrote:
>>> 
>>> The WRONG way to adjust a PC clock is to set the TIME periodically from
>>> some standard.  When you do this then the time on the PC is not running at
>>> a constant rate.  The correct way to do this is to adjust the PC's clocks
>>> RATE.  You make it runs slightly faster if you notice it is getting behind
>>> and slightly slower if it is running fast.
>>> 
>>> Think about what you would do to a real physical clock.  You would not set
>>> it every few minutes, you'd adjust the rate and wait a little while to see
>>> if the adjustment needs refinement or not.
>>> 
>>> ...
>>> 
>>> Most operating systems in use today run NTP to keep their clocks in order.
>>> Well most OSes except for Windows.  Microsoft uses a vey much simplified
>>> version of this that does the wrong thing and periodically sets the PC's
>>> clock.   You could enable this and likely, maybe reach your +/- 100ms
>> goal.
>>> Not the "real" NTP is a free program and not hard to set up so you can
>>> have 1ms level accuracy without much effort and better with some work.
>>> 
 On Tue, Aug 2, 2016 at 8:13 PM, Ron Ott  wrote:
 
 This has probably been covered in the past, but is there a way correct
>> or
 control a PC (Windows 7) clock with the HP 58503A GPS receiver? I just
 bought one (on the way now) and have a copy of satstats50 on hand. I've
 been using Dimension 4 and I'm surprised at the size of correction every
 couple minutes to my PC clock.  I'd be happy if my PC clock were
>> accurate
 to plus/minus 100ms.
 Ron
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>> and follow the 

Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Attila Kinali]

On Fri, 5 Aug 2016 21:35:05 +0200
Magnus Danielson  wrote:

> > From a "Time Nuts" point of view none of the above are even close to
> > accurate clocks.  A microsecond is a very course and crude measure of
> > time.  Pico and Femto seconds are were it gets interesting.
> 
> Certainly. Look at White Rabbit, which really changes how PTP works.
> It may not be pico second accurate, but you get pretty far with it.

WR achieves sub-ns accuracy. Depending on the environment <200ps offset/skew
are possible.

> > Maybe someday NTP will have a time nuts level of accuracy.  the new up
> > coming version, I hear will be using 64 bits to carry the factional part of
> > a second.  That is truly nuts.
> 
> Well, if NTP takes the main ideas from PTP and White Rabbit, maybe then.

This wont help. The achievable accuracy is dictated by the measurement
and the delay uncertainty. Even with network cards that support time stamping,
you cannot hope to get better than 1/125MHz=8ns. Standard network cards
will just trigger an IRQ at some point after reception and enqueuing of
the packet. The IRQ is measured by the OS, which leads to uncertainties
in the order of several us to a couple of 10s of us. If the card does DMA
the packet directly into main memory, then this value is even more inflated.

The network itself has a relatively high jitter. Assume 10s to 100s of us
on a local network per switch. Once you pass a router, you can assume
jitter in the order of a couple of 100us to a couple of ms per router.

To illustrate this, here a few ping statistics (64byte, 1000 packets each):

Local network, GBit/s, two level1 smart switches:
rtt min/avg/max/mdev = 0.073/0.131/0.362/0.044 ms

Two hosts in colo centers within the same city, same ISP, hence
on the same "network" (ie no conguestion), 4 hops:
rtt min/avg/max/mdev = 0.288/0.437/0.620/0.051 ms

Two hosts in colo centers, within the same city, different ISP
but with direct peering (ie no conguestion), 9 hops:
rtt min/avg/max/mdev = 2.916/3.008/3.505/0.078 ms

Two hosts in colo centers, one in Switzerland, one in Germany, 9 hops
rtt min/avg/max/mdev = 12.636/12.947/28.943/0.609 ms

These are all well connected machines, with "carrier grade" networks
inbetween. No consumer internet connections with their huge delays
and jitter.

So, best you can hope for is an jitter of ~50us rms within the same
city with _good_ network connections. Once the distance increases
and especially if you get routers with conquestion inbetween, then
the delay and its jitter rise quickly.


Attila Kinali

-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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[time-nuts] Oscillator Phase Noise: A 50-Year Review

[Tom Van Baak]

Here's a new article, on IEEE's site (and this one's free):

"Oscillator Phase Noise: A 50-Year Review", by David B. Leeson
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7464875



Also, a few months IEEE had a "Special Issue to celebrate the 50th anniversary 
of the Allan Variance".
The full list of papers is here:
http://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=7445917

Most of the articles are behind the IEEE paywall. Some free exceptions here:

"Introduction to the Special Issue on Celebrating the 50th Anniversary of the 
Allan Variance"
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7445935

"The Parabolic Variance (PVAR): A Wavelet Variance Based on the Least-Square 
Fit"
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7323846
also at:
http://arxiv.org/pdf/1506.00687.pdf

"Simulations of the Hadamard Variance: Probability Distributions and Confidence 
Intervals"
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7350241



Best of all, a free version of the David Allan and Judah Levine paper is here:

"A Historical Perspective on the Development of the Allan Variances and Their 
Strengths and Weaknesses"
http://tf.boulder.nist.gov/general/pdf/2834.pdf

/tvb
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Re: [time-nuts] GPS antenna selection — lightning

[Ian Stirling]

On 08/05/2016 01:45 PM, Bob Camp wrote:


A ten foot long antenna cable is no more or less an issue indoors than a ten 
foot serial cable
to a laptop or a ten foot test lead running off of a DVM. They all will pick up 
a spike if the field
is strong enough. If you are in a high risk location, then yes you will need to 
go to extremes
for all of those cables. In some cases the only real answer is an external 
faraday cage around
the entire structure (plus a lot of other stuff).


  My outside GPS aerial came with the NTBW50AA that's still available
from RDR Electronics. It is on a plastic pole tied to the corner of my
deck and is about 12 feet above the ground. It works with the Lucent
RFTG-u pair as well. The 70 ohm cable is about 40 feet long and both
GPSDOs lock quickly from cold in my cellar lab/shack.

  My first venture with GPS was with my Trimble Flightmate Pro that
I bought in October 1993. I knew GPS was supposed to be a precise time
signal. I had built and programmed a Science of Cambridge SC/MP
(INS8060) based computer that decoded the MSF Rugby (no longer there)
60 kHz signal in 1979, still using it in 1994. Comparing it to the
received GPS time on the Trimble, I was dismayed. My records show
that on 1994 June 23 1700 UTC, GPS, or the Trimble, was a whopping
3 seconds slow,vbehind. 1994 July 03 1538 UTC, zero, seemed to be
synchronous. Same day, 1545, 1/2 a second slow. 1552, 2 seconds slow.
1556 1/2 a second slow. I suspect this was due to Selective Availability
that was not turned off until President Clinton ordered it off
in May 2000.

  I have a Navsync CW12-TIM that I bought in 2009. Its diminutive
antenna sticks magnetically to a steel filing cabinet in my office.
I get a good signal and lock there.

In August 2003, I put my hand out of the back door to test the rain.
A lightning bolt split a tree 60 feet away - my wife called me Thor
for many years. The doorbell rang, the garage door control board was
fried and needed replacing, a router in my upstairs office was
blackened, and in 2003, every television and computer monitor in the
house was a CRT - every one of them had to go through several degaussing
sessions.

Best wishes,
Ian, G4ICV, AB2GR
--
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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Magnus Danielson]

Chris,

On 08/05/2016 03:39 AM, Chris Albertson wrote:

I always wonder why people try all kinds of solutions when there are two
known to work as well as theoretically possible.

There is NTP and PTP.

NTP was released to the world in 1985, about 30 years ago.  The algorithm
has been in peer reviewed papers and the source code gets reviewed
continuously by experts in the field and when one of them finds a problem
solutions are discussed and corrections are made.  After 30 years of
continuous review and revision it is close to as good as it will get.
(except for possible security issues in the implementation)  There is a
very active community of academics and computer scientists that keep NTP up
to date.Its problem is that it is designed to work over a public
network that the user has no control over so the assumption must be made
that the network equipment has only some minimum features.  NTP's accuracy
tops out (with great effort) at about 1 microsecond but typically 1
millisecond


With essentially the same messages, but altered rules better performance 
can most likely be achieved in NTP. I'm not at all convinced that 
several of the assumptions in NTP is very useful or valid.



PTP on the other hand is designed to do about the same as NTP but over a
local network the user has complete control over and requires specialized
networking equipment.  PTP accuracy routinely breaks 1uSec but can't work
so well over a public Internet.

If these two where not free, easy to set up and well supported then it
might be worth looking for something else.


It is worth looking for something else, because each have their 
technological and practical limits.



From a "Time Nuts" point of view none of the above are even close to
accurate clocks.  A microsecond is a very course and crude measure of
time.  Pico and Femto seconds are were it gets interesting.


Certainly. Look at White Rabbit, which really changes how PTP works.
It may not be pico second accurate, but you get pretty far with it.


Maybe someday NTP will have a time nuts level of accuracy.  the new up
coming version, I hear will be using 64 bits to carry the factional part of
a second.  That is truly nuts.


Well, if NTP takes the main ideas from PTP and White Rabbit, maybe then.

PTP adds hardware time-stamping and attempts to compensate one-way 
delays that otherwise eats precision for breakfast.


White rabbit attempts much higher resolution while doing it, adding high 
resolution measures and Synchronous Ethernet into the mix, letting PTP 
be relatively time-insensitive message vehicle.



Yes, there is room for more software if maybe one needs to transform time
under conditions not covered by NTP or PTP or needs to do much better than
1uSec.  But typically when that happens we resort to hardware solutions
like 1PPS distributions and/or 10MHz distortions or common view of GPS
carriers signals.  Packetized network just don't work if you need to be
much better than 1uSec.


Slowly pushing down there, but there is a lot of things to care about, 
and tradition to break with.


NTP might work nicely for you, PTP might help you too, but you can do 
better in several regards. There is work to be done, and there is other 
systems out there already.


Cheers,
Magnus


On Thu, Aug 4, 2016 at 11:47 AM, David  wrote:


The old Tardis program for Windows (Tardis2000 now) handles it
correctly by altering the rate and only jamming the time if it is
outside of a specified window but I do not think its GPS mode supports
the 1 PPS signal.

I am not sure if Tardis works with Windows 7 and above though; I
forget to test it on my Windows 7 test system when I had it.  It is a
pretty old (but free) program.

On Tue, 2 Aug 2016 23:28:06 -0700, you wrote:


The WRONG way to adjust a PC clock is to set the TIME periodically from
some standard.  When you do this then the time on the PC is not running at
a constant rate.  The correct way to do this is to adjust the PC's clocks
RATE.  You make it runs slightly faster if you notice it is getting behind
and slightly slower if it is running fast.

Think about what you would do to a real physical clock.  You would not set
it every few minutes, you'd adjust the rate and wait a little while to see
if the adjustment needs refinement or not.

...

Most operating systems in use today run NTP to keep their clocks in order.
Well most OSes except for Windows.  Microsoft uses a vey much simplified
version of this that does the wrong thing and periodically sets the PC's
clock.   You could enable this and likely, maybe reach your +/- 100ms

goal.

 Not the "real" NTP is a free program and not hard to set up so you can
have 1ms level accuracy without much effort and better with some work.

On Tue, Aug 2, 2016 at 8:13 PM, Ron Ott  wrote:


This has probably been covered in the past, but is there a way correct

or

control a PC (Windows 7) clock with the HP 58503A GPS receiver? I just
bought one (on 

Re: [time-nuts] Best choice for GPS active antenna voltage?

[Bob Camp]

Hi

If you are doing your own antenna supply:

1) Make very sure it is current limited at some rational level (say 150 ma). A 
resettable fuse may be fine for this. 

2) Make sure you have some way to detect a short on the antenna. 

3) Put in some sort of surge suppression. A microwave compatible TVS at the 
antenna input is the best / first step. Some form of isolation to the main 
supply is a good second step.

4) At least rate everything so a 12V supply could be cobbled into the circuit. 
You never know when 
you might get a good deal on a high voltage antenna. 

5) Unless you are only running mag mount “car” antennas, you need +5 / +3.3 
selectable
on the board.

6) If you have to do your own RF isolation / DC injection, design it as a 
bandpass (or at least
a high pass) filter. The more energy you eliminate below 400 MHz, the less your 
TVS gets
hit with in most cases. 

Lots of fun..

Bob

> On Aug 5, 2016, at 10:51 AM, Nick Sayer via time-nuts  
> wrote:
> 
> In designing boards with the Venus838LPx-T module, I must supply external 
> antenna power myself. This is in contrast to the PA6H I’ve been using which 
> internally supplies 3.3v active antenna power (and measures it for loading to 
> switch between the internal and external antenna. The Venue module does not 
> have an internal antenna).
> 
> I therefore have the opportunity to select between 3.3v and 5v power to feed 
> the external antenna. I could in principle do something more exotic, but I 
> can’t imagine another option that would be better.
> 
> So far, 3.3v has worked with all of the antennae I’ve used, but the sample 
> size is two (four if you count active GPS splitters in the mix).
> 
> In perusing the list, it sounds to me like modern antennae expect 3.3v, but I 
> thought I’d explicitly ask rather than assume.
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Re: [time-nuts] GPS antenna selection

[albertson . chris]

If you use plastic then paint it. UV light from the sun makes it brittle. 
Plastic electrical conduit however is UV proof   

I used larger size metal with a 3/4 x 1 fiting

How to ground a plastic mast?  You'd need a ground block like the cable TV  
guys use. But with steel mast you put a clamp on the mast

> On Aug 5, 2016, at 2:03 AM, Hal Murray  wrote:
> 
> 
> albertson.ch...@gmail.com said:
>> Next You want one that will last basically "forever" outdoors.  The best
>> kind have a plastic radome over a metal base.  The base has pipe threads for
>> mounting on a standard 3/4" galvanized plumbing pipe.  The coax wires goes
>> down this pie and never sees the light of day or rain water either
> 
> Triva dept...
> 
> Plastic pipe has a slightly smaller ID.  An N connector just barely fits 
> metal pipe.  It doesn't fit in plastic pipe.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Ron Ott]

The Meinberg page I'm reading has NTP downloads for Windows XP and newer and 
for older versions of Windows. If you meant a special version of NTP for 
Windows 7, I didn't see mention of it.
Ron
  From: David J Taylor 
 To: time-nuts@febo.com 
 Sent: Friday, August 5, 2016 12:30 AM
 Subject: Re: [time-nuts] Using the HP 58503a to correct your PC clock
   
Doesn't Meinberg have a Win7 version of ntp on their homepage ?

Why not use that

CFO
===

Installation guide and Win-7/8/10 notes here:

  http://www.satsignal.eu/ntp/setup.html

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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Re: [time-nuts] GPS antenna selection — lightning

[Bob Camp]

Hi

A ten foot long antenna cable is no more or less an issue indoors than a ten 
foot serial cable
to a laptop or a ten foot test lead running off of a DVM. They all will pick up 
a spike if the field
is strong enough. If you are in a high risk location, then yes you will need to 
go to extremes
for all of those cables. In some cases the only real answer is an external 
faraday cage around
the entire structure (plus a lot of other stuff).  

Bob

> On Aug 5, 2016, at 10:37 AM, Eric Scace  wrote:
> 
> Unfortunately, an antenna, cable, or piece of electronics located indoors is 
> just as susceptible to lightning surges as one that is outdoors.
> 
> Lightning-induced surges couple into these systems electromagnetically across 
> a wide range (VLF to SHF) of frequencies. When you think about your home from 
> an electromagnetic viewpoint, just imagine your structure with all 
> non-conductive materials absent. For a typical wood or brick/stone house in 
> North America, what you are left with is:
> metal plumbing pipes and fixtures, with their geometry suspended in space
> house wiring, CATV, Ethernet, and telephone cabling, and their service drops, 
> all suspended in space
> electrical & electronic circuits of every kind (WiFi note, computer, 
> appliances), their power supplies and AC power cords, also suspended in space
> metal furniture? That’s hanging out there, suspended in space, too.
> any I-beam or other steel structural elements, some random aluminum flashing, 
> door knobs, and other similar metal construction materials used in the home.
> That is what an electromagnetic pulse sees as it approaches and sweeps over 
> your home… all hovering over a lossy ground plane (earth) its varying 
> dielectric constant.. Each one of those pieces of metal, hanging in space, is 
> an unintentional antenna that experiences voltage differentials and current 
> flows.
> 
> A GPS antenna and its coax line that is installed next to a window is no 
> different from the same antenna/coax installed one meter outside the window… 
> or 10 meters away outside the window. All three installations are effectively 
> “outdoors” from an electromagnetic viewpoint, and all three need effective 
> surge protection from lightning-, cloud-, and precipitation-induced voltage 
> surges.
> 
> (N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands 
> of volts per meter potential differences in moderate-to-heavy snowfall that 
> produced very significant current flows on cables.)
> 
> Surge protection for your antenna, its attachment to your receiver(s), AC/DC 
> power supply lines, and any other signal lines of significant length is cheap 
> insurance.
> 
> My continuously-operating electronics lives in an enclosed rack cabinet — not 
> too much worse than a proper Faraday cage. Every cable entering the cabinet 
> has surge protection at the point of entry. The cabinet is bonded to earth 
> ground by 2” copper flashing. In the past this system lived 22 years on a 
> mountaintop home, 1200 ft above surrounding terrain. Lots of thunderstorms — 
> zero damage/disruptions during that time… a sample size of one, admittedly, 
> but during the first 18 months at that site I had two lightning-surge 
> damaging events before I got serious about protection.
> 
> I have equipment at a coastal site with multiple 130-ft towers. That site had 
> damage events every 2 years or so — even when cables to the “outside” were 
> disconnected, and AC mains power was shut off at the main circuit breaker 
> box. After implementing comprehensive surge protection, we have had zero 
> damage over the last 12 years.
> 
> — Eric
> 
>> On 2016 Aug 04, at 19:46 , Bob Camp  wrote:
>> 
 Grounding the antenna is always a good idea.
>>> 
 A surge suppressor in the line could save you some
 real cost if there is a lightning strike.
>>> 
>>> I did a quick search for SMA/BNC/TNC based surge
>>> protectors and not much did come up, any suggestions
>>> what to use there?
>> 
>> There are a *lot* of them on eBay. Many of them have N connectors on them.
>> 
>>> 
 I don’t know about Austria, but here in the US,
 both are required.
>>> 
>>> Outside definitely, "inside" I'm not sure, but it
>>> won't hurt to have additional protection for the
>>> receiver(s).
>> 
>> It is a good bet that the antenna will be outside. I’d plan it that way.
> 
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[time-nuts] Best choice for GPS active antenna voltage?

[Nick Sayer via time-nuts]

In designing boards with the Venus838LPx-T module, I must supply external 
antenna power myself. This is in contrast to the PA6H I’ve been using which 
internally supplies 3.3v active antenna power (and measures it for loading to 
switch between the internal and external antenna. The Venue module does not 
have an internal antenna).

I therefore have the opportunity to select between 3.3v and 5v power to feed 
the external antenna. I could in principle do something more exotic, but I 
can’t imagine another option that would be better.

So far, 3.3v has worked with all of the antennae I’ve used, but the sample size 
is two (four if you count active GPS splitters in the mix).

In perusing the list, it sounds to me like modern antennae expect 3.3v, but I 
thought I’d explicitly ask rather than assume.
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Re: [time-nuts] GPS antenna selection — lightning

[Eric Scace]

Unfortunately, an antenna, cable, or piece of electronics located indoors is 
just as susceptible to lightning surges as one that is outdoors.

Lightning-induced surges couple into these systems electromagnetically across a 
wide range (VLF to SHF) of frequencies. When you think about your home from an 
electromagnetic viewpoint, just imagine your structure with all non-conductive 
materials absent. For a typical wood or brick/stone house in North America, 
what you are left with is:
metal plumbing pipes and fixtures, with their geometry suspended in space
house wiring, CATV, Ethernet, and telephone cabling, and their service drops, 
all suspended in space
electrical & electronic circuits of every kind (WiFi note, computer, 
appliances), their power supplies and AC power cords, also suspended in space
metal furniture? That’s hanging out there, suspended in space, too.
any I-beam or other steel structural elements, some random aluminum flashing, 
door knobs, and other similar metal construction materials used in the home.
That is what an electromagnetic pulse sees as it approaches and sweeps over 
your home… all hovering over a lossy ground plane (earth) its varying 
dielectric constant.. Each one of those pieces of metal, hanging in space, is 
an unintentional antenna that experiences voltage differentials and current 
flows.

A GPS antenna and its coax line that is installed next to a window is no 
different from the same antenna/coax installed one meter outside the window… or 
10 meters away outside the window. All three installations are effectively 
“outdoors” from an electromagnetic viewpoint, and all three need effective 
surge protection from lightning-, cloud-, and precipitation-induced voltage 
surges.

(N.B.: Snow can be particularly bad for voltage surges. I’ve seen thousands of 
volts per meter potential differences in moderate-to-heavy snowfall that 
produced very significant current flows on cables.)

Surge protection for your antenna, its attachment to your receiver(s), AC/DC 
power supply lines, and any other signal lines of significant length is cheap 
insurance.

My continuously-operating electronics lives in an enclosed rack cabinet — not 
too much worse than a proper Faraday cage. Every cable entering the cabinet has 
surge protection at the point of entry. The cabinet is bonded to earth ground 
by 2” copper flashing. In the past this system lived 22 years on a mountaintop 
home, 1200 ft above surrounding terrain. Lots of thunderstorms — zero 
damage/disruptions during that time… a sample size of one, admittedly, but 
during the first 18 months at that site I had two lightning-surge damaging 
events before I got serious about protection.

I have equipment at a coastal site with multiple 130-ft towers. That site had 
damage events every 2 years or so — even when cables to the “outside” were 
disconnected, and AC mains power was shut off at the main circuit breaker box. 
After implementing comprehensive surge protection, we have had zero damage over 
the last 12 years.

— Eric

> On 2016 Aug 04, at 19:46 , Bob Camp  wrote:
> 
>>> Grounding the antenna is always a good idea.
>> 
>>> A surge suppressor in the line could save you some
>>> real cost if there is a lightning strike.
>> 
>> I did a quick search for SMA/BNC/TNC based surge
>> protectors and not much did come up, any suggestions
>> what to use there?
> 
> There are a *lot* of them on eBay. Many of them have N connectors on them.
> 
>> 
>>> I don’t know about Austria, but here in the US,
>>> both are required.
>> 
>> Outside definitely, "inside" I'm not sure, but it
>> won't hurt to have additional protection for the
>> receiver(s).
> 
> It is a good bet that the antenna will be outside. I’d plan it that way.



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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[Chris Albertson]

I always wonder why people try all kinds of solutions when there are two
known to work as well as theoretically possible.

There is NTP and PTP.

NTP was released to the world in 1985, about 30 years ago.  The algorithm
has been in peer reviewed papers and the source code gets reviewed
continuously by experts in the field and when one of them finds a problem
solutions are discussed and corrections are made.  After 30 years of
continuous review and revision it is close to as good as it will get.
(except for possible security issues in the implementation)  There is a
very active community of academics and computer scientists that keep NTP up
to date.Its problem is that it is designed to work over a public
network that the user has no control over so the assumption must be made
that the network equipment has only some minimum features.  NTP's accuracy
tops out (with great effort) at about 1 microsecond but typically 1
millisecond

PTP on the other hand is designed to do about the same as NTP but over a
local network the user has complete control over and requires specialized
networking equipment.  PTP accuracy routinely breaks 1uSec but can't work
so well over a public Internet.

If these two where not free, easy to set up and well supported then it
might be worth looking for something else.

>From a "Time Nuts" point of view none of the above are even close to
accurate clocks.  A microsecond is a very course and crude measure of
time.  Pico and Femto seconds are were it gets interesting.

Maybe someday NTP will have a time nuts level of accuracy.  the new up
coming version, I hear will be using 64 bits to carry the factional part of
a second.  That is truly nuts.

Yes, there is room for more software if maybe one needs to transform time
under conditions not covered by NTP or PTP or needs to do much better than
1uSec.  But typically when that happens we resort to hardware solutions
like 1PPS distributions and/or 10MHz distortions or common view of GPS
carriers signals.  Packetized network just don't work if you need to be
much better than 1uSec.

On Thu, Aug 4, 2016 at 11:47 AM, David  wrote:

> The old Tardis program for Windows (Tardis2000 now) handles it
> correctly by altering the rate and only jamming the time if it is
> outside of a specified window but I do not think its GPS mode supports
> the 1 PPS signal.
>
> I am not sure if Tardis works with Windows 7 and above though; I
> forget to test it on my Windows 7 test system when I had it.  It is a
> pretty old (but free) program.
>
> On Tue, 2 Aug 2016 23:28:06 -0700, you wrote:
>
> >The WRONG way to adjust a PC clock is to set the TIME periodically from
> >some standard.  When you do this then the time on the PC is not running at
> >a constant rate.  The correct way to do this is to adjust the PC's clocks
> >RATE.  You make it runs slightly faster if you notice it is getting behind
> >and slightly slower if it is running fast.
> >
> >Think about what you would do to a real physical clock.  You would not set
> >it every few minutes, you'd adjust the rate and wait a little while to see
> >if the adjustment needs refinement or not.
> >
> >...
> >
> >Most operating systems in use today run NTP to keep their clocks in order.
> >Well most OSes except for Windows.  Microsoft uses a vey much simplified
> >version of this that does the wrong thing and periodically sets the PC's
> >clock.   You could enable this and likely, maybe reach your +/- 100ms
> goal.
> >  Not the "real" NTP is a free program and not hard to set up so you can
> >have 1ms level accuracy without much effort and better with some work.
> >
> >On Tue, Aug 2, 2016 at 8:13 PM, Ron Ott  wrote:
> >
> >> This has probably been covered in the past, but is there a way correct
> or
> >> control a PC (Windows 7) clock with the HP 58503A GPS receiver? I just
> >> bought one (on the way now) and have a copy of satstats50 on hand. I've
> >> been using Dimension 4 and I'm surprised at the size of correction every
> >> couple minutes to my PC clock.  I'd be happy if my PC clock were
> accurate
> >> to plus/minus 100ms.
> >> Ron
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] GPS antenna selection

[Hal Murray]

hol...@hotmail.com said:
> You might want to try a modern GPS receiver.   I have some cheap (< $10-20)
> GPS modules with on board patch antennas that work indoors,  sitting on the
> floor of the bottom level of a two story stucco-over-wire mesh house,  away
> from windows,  surrounded on all sides by tall trees,  with the patch
> antenna face down on the floor.  They acquire and track sats quite well. 

Brands an/or models?  Do they have PPS?  (or typical USB...)



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Re: [time-nuts] GPS antenna selection

[Hal Murray]

albertson.ch...@gmail.com said:
> Next You want one that will last basically "forever" outdoors.  The best
> kind have a plastic radome over a metal base.  The base has pipe threads for
> mounting on a standard 3/4" galvanized plumbing pipe.  The coax wires goes
> down this pie and never sees the light of day or rain water either 

Triva dept...

Plastic pipe has a slightly smaller ID.  An N connector just barely fits 
metal pipe.  It doesn't fit in plastic pipe.


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Re: [time-nuts] GPS antenna selection

[Björn Gabrielsson]

>> The real question is how much of a sky view you get.
>
>> Ideally you would like a clear view of the sky from
>> about NE clear around to NW (270 degrees).
>
> That would opt for the balcony, as it faces north
> and extends the slanted roof, so basically clear
> view from NE to NW down to the horizon.
>

Take a look at (yes M$ Silverlight is needed...:( )

 http://www.gnssplanningonline.com/

On "Settings" enter
1) your position (lat, lon, h) - or chose approx position from map.
2) change "cutoff" to 0 deg
3) change "Time span" to max (24h).

On "Satellite library"
1) Disable Glonass, Galileo, BeiDou and QZSS (only GPS remain selected)

Then view "Sky Plot". This is an illustration where the satellites can be
seen by your antenna, with no blocking from house, trees, mountains etc.
The blue outer circle represents the horizon, north up, etc. Circle center
is straigt up into the sky. The fainter grey circles shows 30 and 60 deg
elevation from the horizon.

- Moving the time-ruler (lower-right corner) will show the satellites
move over the selected position.
- While moving the time-ruler around, notice that there is a circle
from north horizon:ish and down (with a latitude of ca N45deg, where
there are never any satellites.
- Where this circle is depends on your latitude.  (check N90deg -north
pole and N0deg (equator) to get a feel of how the priority
directions(azimuth)/elevations are.

You can model your specific obstruction environment at different possible
antenna sites with "Settings" -> "Obstructions".

What is an obstruction? it depends, but first order approx is that
anything that blocks your view will count.

What kind of GPS-receivers will you use? Old receivers (10+years) will
need better installations/locations. Modern high sensitivity receivers
will work decently within many houses. For long cable runs, older receiver
will be more picky, etc.

Good luck!

--

Björn



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Re: [time-nuts] GPS antenna selection

[David J Taylor]

Dear fellow time-nuts!

I'm currently investigating my options regarding
GPS antennae (of course for time related purposes)
and I'm really confused by the variety they come
in ... (my apologies in advance for the long post).
[]
Many thanks in advance and my apologies again for
the rather lengthy post. Please feel free to point
me to previous discussion regarding this topic.

All the best,
Herbert

[1] 
http://www.ebay.com/itm/99-Good-GPS-Antenna-SMA-Screw-Needle-10m-Super-Signal-Navigation-DVD-Antenna-/171802461614

   https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/dp/B00LXRQY9A
===

Herbert,

Based on practical experiences here the antenna [1] on the balcony (outside) 
would be more than adequate for a modern receiver.  Receivers from 10-15 
years back are less sensitive and may require an antenna more like [2] (but 
that has BNC connector).


I would try the cheaper antenna first, and it's no great loss if you have to 
abandon it later.


I don't believe that you mentioned what receiver this was for.

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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[time-nuts] GPS antenna selection

[Mark Sims]

I just did a test on my cheapest (3 for $15-$20) GPS module... a V.KEL Sirf III 
receiver.   Indoors, on the lower level floor, away from windows, etc.   I was 
getting 25-35 dBc levels with the patch antenna properly oriented.  With the 
module flipped over and the antenna surface on a hardwood floor (and the 
circuit board/GPS can pointing to the sky and shielding the antenna), signals 
were around 6 dBc lower.  The receiver was even tracking sats that were below 
12 dBc.  GPS receivers have come a long way in the last few years...
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Re: [time-nuts] GPS antenna selection

[Chris Albertson]

I just wrote that the type of cable hardly matters.  I did not think anyone
would try to use RG174.  That is for 1 foot long jumper cables and
oscilloscope probes at most.   If cost is an issue the 75ohm cable TV wire
is cheap and works better then that tiny sized rg175.

There is no need to buy the high priced stuff as you can buy an antenna
with 30db gain and that makes up for the loss in any *reasonable* cable.

On Thu, Aug 4, 2016 at 3:32 PM, Alex Pummer  wrote:

> Hi Herbert,
>
> just look the loss of the cable at 1500 MHz, and you will start to cry at
> 1500MHz tha cable will have cca 30dB for a 30meter long piecebasically
> that RG174 looks very nice with that small antenna but that is the only
> positive aspect. Meinberg in Germany has one up/down converting system,
> which makes it possible to go more than 50 meter.
> On the other hand if you could stay on the balcony and use the cable which
> came with the antenna, 2m  to 3 meter,  you could have a good working
> system, but with 15m RG174  is asking to much. For 1500 MHz BNC is not the
> best solution,
> 73
> KJ6UHN
> Alex
> P.S.: wo ist diese "Austrian countryside"
>
>
> On 8/4/2016 2:29 PM, Herbert Poetzl wrote:
>
>> Dear fellow time-nuts!
>>
>> I'm currently investigating my options regarding
>> GPS antennae (of course for time related purposes)
>> and I'm really confused by the variety they come
>> in ... (my apologies in advance for the long post).
>>
>>
>> Setting:
>>
>> I'm living in a three storey house with a sloped
>> roof, a covered balcony and a larger garden with
>> huge trees on the Austrian countryside (Europe).
>>
>> I've walked around with my smartphone (older one)
>> and I get a GPS position fix within 35s in the
>> garden (nine satellites shown), within 100s on
>> the balcony (also nine satellites), and not a
>> single satellite can be seen indoors.
>>
>> The obvious choice would be to put the antenna on
>> top in the middle of the slanted roof for a perfect
>> sky view, but this brings a number of problems as
>> the roof is very hard to reach and quite high.
>>
>> I have my 'lab' at the floor where the balcony is,
>> so I'm considering putting an antenna there and
>> run about 5-15m of coax cable to the GPS receiver.
>> The advantage there is that the antenna would be
>> somewhat protected (it still gets very hot during
>> summer and very cold during winter, but no rain
>> and no snow) and easy to reach for maintenance.
>>
>> The third alternative would be to put the antenna
>> somewhere in the garden and have a rather long
>> cable running to the house and up to my lab.
>>
>>
>> Antennae:
>>
>> Looking on eBay and Amazon shows a huge pricerange
>> for active GPS antennae with and without cable.
>>
>> It seems to start at about 10 bucks with rather
>> small black boxes [1] designed for cars, probably
>> containing a 25x25 ceramic GPS antenna and an
>> amplifier, progresses over very interesting out-
>> door constructions for boats and whatnot [2] in
>> the 20-100 bucks range and finally tops with high
>> end devices [3] way above 100 bucks.
>>
>> The information about the cheap devices is usually
>> very scarce, but typically boils down to:
>>
>>   1575.42 +/- 5MHz
>>   24-28dB LNA Gain with 10-25mA at (3-5V)
>>
>>   7dB f0 +/- 20MHz
>>   20dB f0 +/- 50MHz
>>   30dB f0 +/- 100MHz
>>
>> They seem to use RG174 and come with SMA as well
>> as BNC connectors (and a number of others as well).
>>
>> The mid range devices seem to use larger antennae
>> with smaller tolerances (+/- 1MHz) and larger
>> voltage ranges for the amplifier (3-13V).
>>
>>
>> Questions:
>>
>>   - What are the key specifications which need to
>> be verified before buying a GPS antenna?
>>
>>   - How can they be compared based on incomplete
>> specifications?
>>
>>   - Is a place on the roof or in the garden worth
>> the trouble over the covered balcony?
>>
>>   - Are there any typical pit-falls or general
>> tips and tricks regarding mounting and cable
>> connection to the receiver?
>>
>> Many thanks in advance and my apologies again for
>> the rather lengthy post. Please feel free to point
>> me to previous discussion regarding this topic.
>>
>> All the best,
>> Herbert
>>
>>
>> [1] http://www.ebay.com/itm/99-Good-GPS-Antenna-SMA-Screw-Needle
>> -10m-Super-Signal-Navigation-DVD-Antenna-/171802461614
>>  https://www.amazon.com/Waterproof-Active-Antenna-28dB-Gain/
>> dp/B00LXRQY9A
>>
>> [2] http://www.ebay.com/itm/Standard-Horizon-XUCMP0014-GPS-
>> Antenna-f-CP150-CP160-CP170/331364914004
>>  https://www.amazon.com/Garmin-010-12017-00-GPS-
>> GLONASS-Antenna/dp/B00EVT2HSE
>>  https://www.amazon.com/SUNDELY®-External-Marine-
>> Antenna-connector/dp/B00D8WAVTC
>>
>> [3] http://www.ebay.com/itm/NEW-FURUNO-GPA018-Gps-dgps-Antenna-/
>> 182223355414
>>  https://www.amazon.com/Garmin-nmea-2000-orders-over/dp/B0089DU96A
>>  ___
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Re: [time-nuts] Using the HP 58503a to correct your PC clock

[David J Taylor]

Doesn't Meinberg have a Win7 version of ntp on their homepage ?

Why not use that

CFO
===

Installation guide and Win-7/8/10 notes here:

 http://www.satsignal.eu/ntp/setup.html

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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Re: [time-nuts] GPS antenna selection

[Chris Albertson]

What matters more than anything else is how good is the view of the sky.

Next You want one that will last basically "forever" outdoors.  The
best kind have a plastic radome over a metal base.  The base has pipe
threads for mounting on a standard 3/4" galvanized plumbing pipe.  The
coax wires goes down this pie and never sees the light of day or rain
water either

The shape of the dome does matter, you want the pointed kind that
birds can not perch on.  If the top is flat od even hemispherical it
will get covered with bird poop.

When I put mine up on the roof most of the work was done in the attic.
I drilled a 1 inch hole and pushed the mast (1" pipe" up through the
hole then secured it with U-straps to a rafter and joist and tugged on
it hard from all directions to make sure it would not move.  Put a
level on it first and check for vertical.   It is no more work to use
a longer pipe than a short one so go up 3 feet above the roof line.

Then while ion top of the roof just flash the hole to prevent a leak
and drop the coax cable down the pip and screw on the antenna to the
mast.

You local building code likely wants you to ground the antenna mast
lust like you would with an old TV antenna.  It is a good idea to
prevent lightening damage to the house.

With the radome typically sealed by o-ring to the base plate and the
lead wire hidden inside a galvanized pipe there is nothing to degrade
over time.  It should be maintenance free for decades or until hit by
lightening


Al the other stuff about what kind of coax to buy and what connectors
are best and so on are "in the noise" the important stuff is (1) view
of the sky and (2) build so you will never in your lifetime have to
fix it

If you must place it near a balcony or window make sure it faces south
as that is where the satellites are, they don't orbit over the poles.


> On Aug 4, 2016, at 2:29 PM, Herbert Poetzl  wrote:
>
>
> Dear fellow time-nuts!
>
> I'm currently investigating my options regarding
> GPS antennae (of course for time related purposes)
> and I'm really confused by the variety they come
> in ... (my apologies in advance for the long post).
>
>
> Setting:
>
> I'm living in a three storey house with a sloped
> roof, a covered balcony and a larger garden with
> huge trees on the Austrian countryside (Europe).
>
> I've walked around with my smartphone (older one)
> and I get a GPS position fix within 35s in the
> garden (nine satellites shown), within 100s on
> the balcony (also nine satellites), and not a
> single satellite can be seen indoors.
>
> The obvious choice would be to put the antenna on
> top in the middle of the slanted roof for a perfect
> sky view, but this brings a number of problems as
> the roof is very hard to reach and quite high.
>
> I have my 'lab' at the floor where the balcony is,
> so I'm considering putting an antenna there and
> run about 5-15m of coax cable to the GPS receiver.
> The advantage there is that the antenna would be
> somewhat protected (it still gets very hot during
> summer and very cold during winter, but no rain
> and no snow) and easy to reach for maintenance.
>
> The third alternative would be to put the antenna
> somewhere in the garden and have a rather long
> cable running to the house and up to my lab.
>
>
> Antennae:
>
> Looking on eBay and Amazon shows a huge pricerange
> for active GPS antennae with and without cable.
>
> It seems to start at about 10 bucks with rather
> small black boxes [1] designed for cars, probably
> containing a 25x25 ceramic GPS antenna and an
> amplifier, progresses over very interesting out-
> door constructions for boats and whatnot [2] in
> the 20-100 bucks range and finally tops with high
> end devices [3] way above 100 bucks.
>
> The information about the cheap devices is usually
> very scarce, but typically boils down to:
>
> 1575.42 +/- 5MHz
> 24-28dB LNA Gain with 10-25mA at (3-5V)
>
> 7dB f0 +/- 20MHz
> 20dB f0 +/- 50MHz
> 30dB f0 +/- 100MHz
>
> They seem to use RG174 and come with SMA as well
> as BNC connectors (and a number of others as well).
>
> The mid range devices seem to use larger antennae
> with smaller tolerances (+/- 1MHz) and larger
> voltage ranges for the amplifier (3-13V).
>
>
> Questions:
>
> - What are the key specifications which need to
>   be verified before buying a GPS antenna?
>
> - How can they be compared based on incomplete
>   specifications?
>
> - Is a place on the roof or in the garden worth
>   the trouble over the covered balcony?
>
> - Are there any typical pit-falls or general
>   tips and tricks regarding mounting and cable
>   connection to the receiver?
>
> Many thanks in advance and my apologies again for
> the rather lengthy post. Please feel free to point
> me to previous discussion regarding this topic.
>
> All the best,
> Herbert
>
>
> [1] 
> http://www.ebay.com/itm/99-Good-GPS-Antenna-SMA-Screw-Needle-10m-Super-Signal-Navigation-DVD-Antenna-/171802461614
>

[time-nuts] GPS antenna selection

[Mark Sims]

You might want to try a modern GPS receiver.   I have some cheap (< $10-20) GPS 
modules with on board patch antennas that work indoors,  sitting on the floor 
of the bottom level of a two story stucco-over-wire mesh house,  away from 
windows,  surrounded on all sides by tall trees,  with the patch antenna face 
down on the floor.  They acquire and track sats quite well.
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Re: [time-nuts] GPS antenna selection

[cfo]

On Thu, 04 Aug 2016 23:29:06 +0200, Herbert Poetzl wrote:

> Dear fellow time-nuts!
> 
> I'm currently investigating my options regarding GPS antennae (of course
> for time related purposes)
> and I'm really confused by the variety they come in ... (my apologies in
> advance for the long post).
> 
> 
> Setting:
> 
> I'm living in a three storey house with a sloped roof, a covered balcony
> and a larger garden with huge trees on the Austrian countryside
> (Europe).

I'm using this type (26dB, N Connector) on my balcony (South).
It's mounted on a 1m waterpipe, that is "stripped" to the balcony fence.

I initially bought a 40dB , but had to change to 26dB , due to too much 
gain.

www.ebay.com/itm/PCTEL-GPS-TMG-26N-26-dB-Internal-Amplifier-Timing-
Reference-Antenna-/232037804675


www.ebay.com/itm/Lucent-Datum-KS24019L112C-GPS-26dB-5V-Antenna-Telecom-
Timing-N-Conn-Andrews-NEW-/361510967153



I use a Tbolt, that have 75ohm impedance , and am using about 25m quad 
shielded 75 ohm , quality sattelite cable from the balcony to the Tbolt.

I'm using a N-->F adapter at the antenna end, that makes it super easy to 
make a diy F-->F connector cable.


I now have installed a quad active antenna splitter (50ohm) , using the 
same 75ohm cable , and a F-->N adapter at the splitter end. And see no 
noticable problems using 75ohm cable there.


CFO
Denmark

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Re: [time-nuts] GPS antenna selection

[Hal Murray]

herb...@13thfloor.at said:
>> Ideally you would like a clear view of the sky from 
>> about NE clear around to NW (270 degrees). 
> That would opt for the balcony, as it faces north and extends the slanted
> roof, so basically clear view from NE to NW down to the horizon. 

You are thinking the short way from NE to NW.  You want the long way so it 
includes South.  Note the "270" up there.  (That assumes you are located well 
north of the equator.)


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Re: [time-nuts] Tardis [WAS: Using the HP 58503a to correct your PC clock]

[Hal Murray]

ron...@sbcglobal.net said:
> I'm working on NTP and have no idea what's happening. The description says
> it takes over the PC clock, excluding other apps.

It doesn't make sense to have more than one program trying to adjust the 
clock.  They will just confuse each other.

I think what that is trying to tell you is to disable any other clock-setting 
programs that may be running.  There is probably something in the system that 
does that.  I don't know anything about Windows so I can't tell you how to 
disable it.  But keep your eye open for something like that.

I think Meinberg used to provide a package that installed NTP and did all the 
right stuff to set it up.


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