Re: [time-nuts] Looking for CA3130E IC...

[Steve .]

Supposedly in stock:
http://www.futurlec.com/ICLinearOpAmps1.shtml

I've dealt with this company several times in the past, no problems other
than very slow shipment to the usa.(Some cases 2-3 months)


Steve

On Fri, Apr 13, 2012 at 12:46 AM, Burt I. Weiner  wrote:

> Hopefully someone out there has a stash of what I'm looking for.  I need 4
> ea IC type CA3130E.  Need this specific number.  It's an 8 pin DIP.  I've
> tried DigiKey and Mouser.  No luck.
>
> Thanks,
>
> Burt, K6OQK
>
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California  U.S.A.
> b...@att.net
> www.biwa.cc
> K6OQK
>
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[time-nuts] Looking for CA3130E IC...

[Burt I. Weiner]

Hopefully someone out there has a stash of what I'm looking for.  I 
need 4 ea IC type CA3130E.  Need this specific number.  It's an 8 pin 
DIP.  I've tried DigiKey and Mouser.  No luck.


Thanks,

Burt, K6OQK

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 



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Re: [time-nuts] Best location for a GPS antenna...?

[gary]

"Early streamer emission"...thems fightin' words!


On 4/12/2012 6:03 PM, Jim Lux wrote:




Controversial is an understatement.
When there was an IEEE journal paper (well reviewed) essentially saying
that they don't work, one of the manufacturers of such devices sued the
author and the IEEE (unsuccessfully).

The same manufacturer proudly proclaims "as used by NASA and the US Air
Force" when what really happened is that both bought them as test
articles, for tests which failed. There's a great picture of a lightning
bolt coming down from the sky, skipping the top of the tower and hitting
the "lightning eliminator" square in the middle of the panel.


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Re: [time-nuts] Best location for a GPS antenna...?

[Bob Camp]

Hi

Oddly enough I've actually worked with an EMP simulator. They indeed put out a 
lot of energy. The lightning hits I've experienced are no where near EMP level 
events.

Bob

On Apr 12, 2012, at 9:07 PM, Chris Albertson wrote:

> On Thu, Apr 12, 2012 at 2:21 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> Do you have a reference for 100' distant strikes routinely destroying
>> receivers?
>> 
>> Bob
>> 
>> 
> 
> The ARRL's "QST" magazine Aug -> Nov 1986 is very good and many people here
> would have access to it.
> They talk about EMP from both atomic weapons and lightening.  The EMP from
> atomic explosions is as you'd yes worse.  If can destroy most electronics
> up to 450 miles away in the worse cast (an explosion in the ionosphere.)
> 
> Lightening has vary wide band energy in its EMP and the farther you are
> away from it the lower the frequency.  So a very close strike might have
> much energy at UHF a strike 50 feet away might be only up to HF range.   So
> it couples to different length conductors depending on the distance.My
> reference to 100 feet means you'd need some length on the feed line and
> data cables.
> 
> There is a good publication from some one at a university in Florida having
> to do with electronics on boats. I can't find it now.
> 
> 
> -Original Message-
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>> Behalf Of Chris Albertson
>> Sent: Thursday, April 12, 2012 3:25 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>> 
>> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
>> wrote:
>> 
>>> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>>> 
 What about mounting the antenna on the side of the metal pole, with the
 top of the pole extending a foot or more above the antenna?
>>> 
>>> 
>> Typically when a receiver or other radio is destroyed it was NOT because of
>> a direct strike.  A strike within maybe 100 feet is enough.  There is a
>> _huge_ EMP field around the strike.  The field will induce large currents
>> in any nearby conductors.   Even if the strike is to bare Earth many feet
>> from the antenna the potential of the earth is raised by say 1,000 volts so
>> now anything connected between ground the power has 1KV across it.
>> 
>> 
>> 
>> 
>> 
>> Chris Albertson
>> Redondo Beach, California
>> ___
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>> 
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>> 
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Best location for a GPS antenna...?

[Jim Lux]

On 4/12/12 12:02 PM, David McGaw wrote:

Best would be to have a lightning rod in the vicinity of and above the
antenna. A sharp-pointed rod does not attract lightning, it REPELS it
and has a cone of protection under it. While the effect is not
understood, it apparently discharges the surrounding air through corona
discharge - the sharper the better.


Cone of protection it is, but it's because the lightning preferentially 
hits the rod, rather than something below it.


There's no discharging the earth/cloud capacitance. That theory has been 
thoroughly debunked, both analytically and experimentally. There's some 
great papers by some scientists at Erico in Australia where they were 
looking for "better designs" for lightning rods, so they set up a test 
facility to replicate the charge distributions and fields in the 
"prestrike" time.  This is very much trickier operation than testing for 
the discharge itself, or for EMP, where you just need a big Marx 
generator.  It's essentially a high voltage arbitrary waveform generator 
into a carefully designed TEM test cell of sorts.





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Re: [time-nuts] Best location for a GPS antenna...?

[Chris Albertson]

On Thu, Apr 12, 2012 at 2:21 PM, Bob Camp  wrote:

> Hi
>
> Do you have a reference for 100' distant strikes routinely destroying
> receivers?
>
> Bob
>
>

The ARRL's "QST" magazine Aug -> Nov 1986 is very good and many people here
would have access to it.
They talk about EMP from both atomic weapons and lightening.  The EMP from
atomic explosions is as you'd yes worse.  If can destroy most electronics
up to 450 miles away in the worse cast (an explosion in the ionosphere.)

Lightening has vary wide band energy in its EMP and the farther you are
away from it the lower the frequency.  So a very close strike might have
much energy at UHF a strike 50 feet away might be only up to HF range.   So
it couples to different length conductors depending on the distance.My
reference to 100 feet means you'd need some length on the feed line and
data cables.

There is a good publication from some one at a university in Florida having
to do with electronics on boats. I can't find it now.


-Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Chris Albertson
> Sent: Thursday, April 12, 2012 3:25 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>
> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
> wrote:
>
> > On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
> >
> >> What about mounting the antenna on the side of the metal pole, with the
> >> top of the pole extending a foot or more above the antenna?
> >
> >
> Typically when a receiver or other radio is destroyed it was NOT because of
> a direct strike.  A strike within maybe 100 feet is enough.  There is a
> _huge_ EMP field around the strike.  The field will induce large currents
> in any nearby conductors.   Even if the strike is to bare Earth many feet
> from the antenna the potential of the earth is raised by say 1,000 volts so
> now anything connected between ground the power has 1KV across it.
>
>
>
>
>
> Chris Albertson
> Redondo Beach, California
> ___
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>
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>



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Best location for a GPS antenna...?

[Jim Lux]

On 4/12/12 12:50 PM, li...@lazygranch.com wrote:

I'd suggest getting Dr. Uman's "All About Lightning" as a starter. You could 
read it in an afternoon, so to be correct, the book is all about lightning, but it 
doesn't contain all the world's knowledge. ;-).  It isn't very technical, though he has 
written technical books as well.


An excellent book, as is the Dover book "Lightning".



Regarding schemes to prevent lightning hits, they are all controversial. That 
is, scientists argue over the effectiveness. The one I see often in the high 
desert looks like a brush made out of metal fibers.



Controversial is an understatement.
When there was an IEEE journal paper (well reviewed) essentially saying 
that they don't work, one of the manufacturers of such devices sued the 
author and the IEEE (unsuccessfully).


The same manufacturer proudly proclaims "as used by NASA and the US Air 
Force" when what really happened is that both bought them as test 
articles, for tests which failed.  There's a great picture of a 
lightning bolt coming down from the sky, skipping the top of the tower 
and hitting the "lightning eliminator" square in the middle of the panel.





I've got to see ground hits in the desert twice. Amazing. The spot hit glows 
yellow, which I presume is sodium ionization.


Or, "yellow heat" as in blackbody radiation.. it gets hot enough to fuse 
sand into glass (fulgurites) and it takes a while to cool off.  Some 
years back, I was trying to make artificial fulgurites in my back yard 
with large high voltage capacitor banks (hey, quarter shrinking gets 
boring after a while).







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Re: [time-nuts] Best location for a GPS antenna...?

[Mark Spencer]

I was a guest in a home that lost power due to a lightning strike on the power 
pole across the street.   Once the power company replaced the transformer on 
the pole the power came back on and as far as I know there was no lasting 
damage to any of the electronics in the house.  I was sleeping in the bedroom 
that was closest to the pole that was hit and the flash woke me up.   None of 
my electronic gear (laptop, cell phone, black berry etc) that was plugged in 
seemed any worse for wear.  I was lucky. 
This was in a lightning prone area and and I believe the owners had surge 
suppressors on their electronics.   

I realize all lightning strikes will be different but my experience was similar 
to the ones outlined by Bob. 

--
On Thu, 12 Apr, 2012 7:54 PM EDT Bob Camp wrote:

>Hi
>
>In the same area of "what I have seen". I used to live in a neighborhood where 
>strikes were quite common. It was a rare summer month that there was not one 
>or more hits in the neighborhood. Nobody's house burned down. They (I) did not 
>loose every electronic device within 100' or 1000' of the strike. The thing 
>*least* likely to be bothered turned out to be stuff with receivers in them 
>(radios and the like). 
>
>Bob
>
>On Apr 12, 2012, at 6:58 PM, EB4APL wrote:
>
>> Hi,
>> 
>> I have a personal reference:  In the Deep Space tracking facility where I 
>> used to work some 20 years ago it was very common to have minicomputers 
>> damaged by strikes in the antenna.  This antenna was located about 1000' 
>> from the control room and there were an elaborate grounding system both in 
>> the antenna (mainly intended to protect from lightning) and in the control 
>> room, but we got TTL chips damaged very often during thunderstorms.  The 
>> common believe was the high currents induced in the ground cabling caused  
>> voltage spikes inside the computer cabinets enough to fry the chips.  I 
>> don't remember failures in the receivers, transmitters or other subsystems, 
>> but minicomputers were the usual targets, one or two chips each time.
>> 
>> Regards,
>> Ignacio, EB4APL
>> 
>> 
>> On 12/04/2012 23:21, Bob Camp wrote:
>> Hi
>> 
>> Do you have a reference for 100' distant strikes routinely destroying
>> receivers?
>> 
>> Bob
>> 
>> -Original Message-
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>> Behalf Of Chris Albertson
>> Sent: Thursday, April 12, 2012 3:25 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>> 
>> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
>> wrote:
>> 
>>> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>>> 
>>> What about mounting the antenna on the side of the metal pole, with the
>>> top of the pole extending a foot or more above the antenna?
>>> 
>> Typically when a receiver or other radio is destroyed it was NOT because of
>> a direct strike.  A strike within maybe 100 feet is enough.  There is a
>> _huge_ EMP field around the strike.  The field will induce large currents
>> in any nearby conductors.   Even if the strike is to bare Earth many feet
>> from the antenna the potential of the earth is raised by say 1,000 volts so
>> now anything connected between ground the power has 1KV across it.
>> 
>> 
>> 
>> 
>> 
>> Chris Albertson
>> Redondo Beach, California
>> ___
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>
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Re: [time-nuts] Best location for a GPS antenna...?

[lists]

ESD is not an issue for chips that don't touch the outside world. It is only a 
handling issue. 

If anything, ESD has got worse over the years as geometries have decreased. 
Latch-up, a potential issue with boards that get surges, has improved over the 
years with epi or dielectric isolation schemes. 
-Original Message-
From: Joseph M Gwinn 
Sender: time-nuts-boun...@febo.com
Date: Thu, 12 Apr 2012 19:39:14 
To: 
Reply-To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Best location for a GPS antenna...?

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Re: [time-nuts] GPS Splitter

[Kasper Pedersen]

On 04/13/2012 12:19 AM, iov...@inwind.it wrote:

> Just found on the auction site: 
> Item number: 220957196441
> Specs available at the manufacturer's website.
> I have no idea if it is worth the price.


It feels mechanically indestructible, and works.

I have a tbolt powering it, and a 3.3V (skytraq venus cheap nav)
receiver on another port to allow me to make plots like
http://wap.taur.dk/gc8.png
which is the view from a puck on the balcony - it has workable view,
east-northeast is through roof.
And the tbolt reports slightly better SNR (the antenna alone has less
gain than the tbolt likes) with it in series.

The N-covers it comes with are just covers, not terminators, so I
suspect it to be the high-iso (+10dB) version. I have not yet actually
measured the gain, work's generator stops at 1GHz so I need to build a
doubler first.

/Kasper Pedersen

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Re: [time-nuts] Best location for a GPS antenna...?

[Bob Camp]

Hi

In the same area of "what I have seen". I used to live in a neighborhood where 
strikes were quite common. It was a rare summer month that there was not one or 
more hits in the neighborhood. Nobody's house burned down. They (I) did not 
loose every electronic device within 100' or 1000' of the strike. The thing 
*least* likely to be bothered turned out to be stuff with receivers in them 
(radios and the like). 

Bob

On Apr 12, 2012, at 6:58 PM, EB4APL wrote:

> Hi,
> 
> I have a personal reference:  In the Deep Space tracking facility where I 
> used to work some 20 years ago it was very common to have minicomputers 
> damaged by strikes in the antenna.  This antenna was located about 1000' from 
> the control room and there were an elaborate grounding system both in the 
> antenna (mainly intended to protect from lightning) and in the control room, 
> but we got TTL chips damaged very often during thunderstorms.  The common 
> believe was the high currents induced in the ground cabling caused  voltage 
> spikes inside the computer cabinets enough to fry the chips.  I don't 
> remember failures in the receivers, transmitters or other subsystems, but 
> minicomputers were the usual targets, one or two chips each time.
> 
> Regards,
> Ignacio, EB4APL
> 
> 
> On 12/04/2012 23:21, Bob Camp wrote:
>> Hi
>> 
>> Do you have a reference for 100' distant strikes routinely destroying
>> receivers?
>> 
>> Bob
>> 
>> -Original Message-
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>> Behalf Of Chris Albertson
>> Sent: Thursday, April 12, 2012 3:25 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>> 
>> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
>> wrote:
>> 
>>> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>>> 
 What about mounting the antenna on the side of the metal pole, with the
 top of the pole extending a foot or more above the antenna?
>>> 
>> Typically when a receiver or other radio is destroyed it was NOT because of
>> a direct strike.  A strike within maybe 100 feet is enough.  There is a
>> _huge_ EMP field around the strike.  The field will induce large currents
>> in any nearby conductors.   Even if the strike is to bare Earth many feet
>> from the antenna the potential of the earth is raised by say 1,000 volts so
>> now anything connected between ground the power has 1KV across it.
>> 
>> 
>> 
>> 
>> 
>> Chris Albertson
>> Redondo Beach, California
>> ___
>> 
> 
> ___
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Re: [time-nuts] Best location for a GPS antenna...?

[Joseph M Gwinn]

I think I know why.  I worked on such computers, and they were very
sensitive to ESD.  If you touched the cabinet during the winter, when it's
very dry, the spark would be enough to crash the computer, although
permanent damage was rare.  The problem was that the computers were
under-designed back then.  Now days, all such electronics has to pass a
variety of ESD and power surge tests.  Not that they will necessarily
survive a full surge.  For this, one buys a large surge arrester and
installs it on the power panel.


Joe Gwinn



From:   EB4APL 
To: time-nuts@febo.com
Date:   04/12/2012 07:00 PM
Subject:Re: [time-nuts] Best location for a GPS antenna...?
Sent by:time-nuts-boun...@febo.com



Hi,

I have a personal reference:  In the Deep Space tracking facility where
I used to work some 20 years ago it was very common to have
minicomputers damaged by strikes in the antenna.  This antenna was
located about 1000' from the control room and there were an elaborate
grounding system both in the antenna (mainly intended to protect from
lightning) and in the control room, but we got TTL chips damaged very
often during thunderstorms.  The common believe was the high currents
induced in the ground cabling caused  voltage spikes inside the computer
cabinets enough to fry the chips.  I don't remember failures in the
receivers, transmitters or other subsystems, but minicomputers were the
usual targets, one or two chips each time.

Regards,
Ignacio, EB4APL


On 12/04/2012 23:21, Bob Camp wrote:
> Hi
>
> Do you have a reference for 100' distant strikes routinely destroying
> receivers?
>
> Bob
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Chris Albertson
> Sent: Thursday, April 12, 2012 3:25 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>
> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
> wrote:
>
>> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>>
>>> What about mounting the antenna on the side of the metal pole, with the
>>> top of the pole extending a foot or more above the antenna?
>>
> Typically when a receiver or other radio is destroyed it was NOT because
of
> a direct strike.  A strike within maybe 100 feet is enough.  There is a
> _huge_ EMP field around the strike.  The field will induce large currents
> in any nearby conductors.   Even if the strike is to bare Earth many feet
> from the antenna the potential of the earth is raised by say 1,000 volts
so
> now anything connected between ground the power has 1KV across it.
>
>
>
>
>
> Chris Albertson
> Redondo Beach, California
> ___
>

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Re: [time-nuts] Thoughts on lightning protection measures....

[SAIDJACK]

Hi Bjoern,
 
Possibly, I am just reciting what I read in the Nordig requirements a  
looong time ago. Maybe they are worried about far north permafrost scenarios  
that go deeper? The requirements for receiver RF input surge protection were  
much higher than the usual US requirements..
 
bye,
Said
 
 
In a message dated 4/12/2012 15:38:55 Pacific Daylight Time,  
b...@lysator.liu.se writes:

Said,

The ground is a decent thermal isolator. And will in  nordic countries not
often go deeper than about 1 meter. You need to build  your houses
foundation "deep" enough to stand on non frozen ground.  Otherwise your
house will move to much with the seasons and likely break.  It is not that
hard to get your ground pole deep enough to avoid freezing  problems.

-- 

Björn


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Re: [time-nuts] GPS Splitter

[Azelio Boriani]

I have one, it is OK.

On Fri, Apr 13, 2012 at 12:19 AM, iov...@inwind.it  wrote:

> Just found on the auction site:
> Item number: 220957196441
> Specs available at the manufacturer's website.
> I have no idea if it is worth the price.
> Might be of interest.
> Antonio I8IOV
> Note: I'm not affiliated.. etc ...etc..
>
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Re: [time-nuts] WWVB phase modulation test April 15-16

[Charles P. Steinmetz]

Hal wrote:


How many of you have used the Tek scope-probe to BNC adapter?  I tried a bit
but couldn't find anything on the web.  The idea was (roughly) that you put a
BNC Tee in the line you wanted to watch and this magic gizmo on the Tee.


I have some.  I don't use them often, but they are very useful on 
occasion (when you want to insert a sampling port in coax with 
minimal disturbance to the line).  You normally use them with 10x 
probes to minimize the capacitive loading at the sampling port.  They 
used to appear on eBay quite frequently for $2-$5 each, but for the 
last year or so sellers seem to be very proud of them.


Note that you need one that matches your probe tip (5 mm, 3.5 mm, or 
2.5 mm ground sleeve).


Best regards,

Charles







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Re: [time-nuts] Best location for a GPS antenna...?

[EB4APL]

Hi,

I have a personal reference:  In the Deep Space tracking facility where 
I used to work some 20 years ago it was very common to have 
minicomputers damaged by strikes in the antenna.  This antenna was 
located about 1000' from the control room and there were an elaborate 
grounding system both in the antenna (mainly intended to protect from 
lightning) and in the control room, but we got TTL chips damaged very 
often during thunderstorms.  The common believe was the high currents 
induced in the ground cabling caused  voltage spikes inside the computer 
cabinets enough to fry the chips.  I don't remember failures in the 
receivers, transmitters or other subsystems, but minicomputers were the 
usual targets, one or two chips each time.


Regards,
Ignacio, EB4APL


On 12/04/2012 23:21, Bob Camp wrote:

Hi

Do you have a reference for 100' distant strikes routinely destroying
receivers?

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: Thursday, April 12, 2012 3:25 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?

On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
wrote:


On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:


What about mounting the antenna on the side of the metal pole, with the
top of the pole extending a foot or more above the antenna?



Typically when a receiver or other radio is destroyed it was NOT because of
a direct strike.  A strike within maybe 100 feet is enough.  There is a
_huge_ EMP field around the strike.  The field will induce large currents
in any nearby conductors.   Even if the strike is to bare Earth many feet
from the antenna the potential of the earth is raised by say 1,000 volts so
now anything connected between ground the power has 1KV across it.





Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Thoughts on lightning protection measures....

[bg]

Said,

The ground is a decent thermal isolator. And will in nordic countries not
often go deeper than about 1 meter. You need to build your houses
foundation "deep" enough to stand on non frozen ground. Otherwise your
house will move to much with the seasons and likely break. It is not that
hard to get your ground pole deep enough to avoid freezing problems.

-- 

   Björn

> Hi Attila,
>
> if I remember correctly, the issue is that the "ground" at the house is
> not a "real" ground when the earth is frozen, as the resistance of frozen
> earth goes up substantially over non-frozen earth. So it's like not having
> grounded the wires at all.
>
> This is a real issue for cables brought to the house (cable TV, telephone,
> etc etc) as those cables are grounded somewhere else on the other side,
> and
> thus  there may be 1000's or even 1's Volts between the two "grounds",
> even (or  especially) for just a proximity strike. As mentioned by someone
> else, all bets  are off anyway's for direct hits, not much will survive a
> direct hit.
>
> It's been a long time since I designed cable TV receivers, but the specs
> are here, and I think there are some explanations in there somewhere:
>
> _http://www.nordig.org/specifications.htm_
> (http://www.nordig.org/specifications.htm)
>
> bye,
> Said
>
>
>
>
> In a message dated 4/12/2012 09:54:40 Pacific Daylight Time,
> att...@kinali.ch writes:
>
> Hmm?  That sounds interesting. In switzerland, and AFAIK in most  european
> countries, power feeds have to be grounded at the entry of the  house
> (ie the neutral conductor is grounded). This should protect the
> electrical
> equipment from such ground jumps as you discribe. Or do i miss  something?
>
> Attila  Kinali
>
>
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Re: [time-nuts] Thoughts on lightning protection measures....

[SAIDJACK]

Hi Attila,
 
if I remember correctly, the issue is that the "ground" at the house is  
not a "real" ground when the earth is frozen, as the resistance of frozen  
earth goes up substantially over non-frozen earth. So it's like not having  
grounded the wires at all.
 
This is a real issue for cables brought to the house (cable TV, telephone,  
etc etc) as those cables are grounded somewhere else on the other side, and 
thus  there may be 1000's or even 1's Volts between the two "grounds", 
even (or  especially) for just a proximity strike. As mentioned by someone 
else, all bets  are off anyway's for direct hits, not much will survive a 
direct hit.
 
It's been a long time since I designed cable TV receivers, but the specs  
are here, and I think there are some explanations in there somewhere:
 
_http://www.nordig.org/specifications.htm_ 
(http://www.nordig.org/specifications.htm) 
 
bye,
Said
 
 
 
 
In a message dated 4/12/2012 09:54:40 Pacific Daylight Time,  
att...@kinali.ch writes:

Hmm?  That sounds interesting. In switzerland, and AFAIK in most  european
countries, power feeds have to be grounded at the entry of the  house
(ie the neutral conductor is grounded). This should protect the  electrical
equipment from such ground jumps as you discribe. Or do i miss  something?

Attila  Kinali


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[time-nuts] GPS Splitter

[iov...@inwind.it]

Just found on the auction site: 
Item number: 220957196441
Specs available at the manufacturer's website.
I have no idea if it is worth the price.
Might be of interest.
Antonio I8IOV
Note: I'm not affiliated.. etc ...etc..

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Re: [time-nuts] Re-radiating a GPS signal...??

[bg]

It is well known that vertical accuracy is worse by about 1.8 times the
horizontal accuracy. It is true this is geometrically caused. In indoor
scenarios high sensitive receivers have a vertical bias due to excessive
multipath. More or less all received signals have bounced multiple times
to reach the receiver in the worst scenarios. This however has nothing to
do with a rerad-system, where your rerad signal will be much stronger than
the natural one. Otherwise there would be no need for a rerad-system in
the first place. Also a correctly installed rerad-system will not give
excessive multipath problems. Vertiacal biasing is not caused by
(correctly) installed rerad systems.

--

Björn

> Purely geometrically, the fix solution is computed as the intersection
> point of spheres with the radii determined by the propagation time, and
> the centers by the positions of the satellites (practically not all
> spheres intersect in the same geometrical point, so an average is
> computed).
> If the GPS Rx would receive simultaneously all satellites, considered
> evenly distributed on a sphere, then the added path delays would mostly
> cancel out - but if only the visible satellites are accounted for, we
> will have an unbalanced system, approximated to an hemispehere, in which
> the horizontal error will be low, as the longer paths cancel mostly out,
> but for the vertical one it's not the case.
>
> Any GPS receiver will exhibit lower vertical precision than the
> horizontal one.
> The same phenomenon, of low precision, and biasing of position is
> evident if just a part of the constellation is used (an obstacle
> obscures a large part of the sky).
>
> The internal delays of the Rx are mostly fixed and known, so they can be
> accounted for, and compensated in the firmware fix solution, but the
> cable length is a variable (depending on the installation) factor, not
> accounted for.
>
>
> On 4/12/2012 7:15 PM, b...@lysator.liu.se wrote:
>> Not at all!
>>
>> The (first) receiving antenna defines the position you get out of a long
>> antenna cable or a reradiating system. The delays in LNA, filters,
>> cables,
>> rerad antenna, free air between rerad antenna and final receiving
>> antenna
>> ALL goed into the receiver clock error. This is clear both from a
>> theoretical point, from most standard GPS texts and from practical
>> experience from multiple installations I have used over the years.
>>
>> If you disagree, please provide evidence.
>>
>> --
>>
>>Björn
>>
>>> Not quite, the delay of the antenna cable is affecting less the
>>> horizontal position (it depends also on the current received
>>> constellation geometry), but mostly the height ASL of the fix point,
>>> prolonging simultaneously all the paths from the satellites with a
>>> fixed
>>> value.
>>> Also, the propagation speed in a cable is significantly lower than in
>>> free space - the perceived delay increase is ~1.5 times for usual
>>> cables
>>> (~.67 velocity factor), and the computed fix point would have a lower
>>> height ASL than the real one.
>>>
>>> Those relaying systems are merely good for an approximate location fix,
>>> mostly for not loosing the GPS signal in covered areas so that the
>>> reacquire of the real signal is faster, with almost no perceived
>>> discontinuity.
>>>
>>>
>>> On 4/12/2012 6:11 PM, David McGaw wrote:
 The time/position fix would be from the location of the receiving
 antenna of the repeater, degraded only by noise.

 This should work if both antennas have good back-side rejection
 (choke-rings are particularly good for this but perhaps any good
 timing
 antenna could meet this), the re-transmitting antenna is close to
 being
 directly under the receiving antenna, and the system gain is low
 enough.
 The problem I would see in a room that is not fully shielded is
 interference between the direct and retransmitted signals at the
 receiver under test.

 David N1HAC

 On 4/12/12 10:17 AM, MailLists wrote:
> GPS being extremely time-dependent, any delay introduced will affect
> positioning precision. Also, the signal is too weak for such an
> amplification/echo cancelling signal chain.
> Passive relaying, or using at most a simple amplifier with low enough
> gain, and short signal delay, remain the only feasible concepts.
>
> On 4/12/2012 4:48 PM, Azelio Boriani wrote:
>> Passive UHF TV repeaters were in use in Italy too. Nowadays, for the
>> DVB-T
>> TV, active gap-fillers are used instead. Active gap-fillers are
>> same-channel repeaters with the necessary, sophisticated echo
>> suppression
>> technique. We have developed our echo suppression signal processor
>> on
>> a
>> Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS
>> CDMA.
>>
>> On Thu, Apr 12, 2012 at 3:29 PM, Alan
>> Meliawrote:
>>
>>> If the isolation is good and the "clear view" sig

Re: [time-nuts] Best location for a GPS antenna...?

[Bob Camp]

Hi

Do you have a reference for 100' distant strikes routinely destroying
receivers?

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: Thursday, April 12, 2012 3:25 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?

On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
wrote:

> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>
>> What about mounting the antenna on the side of the metal pole, with the
>> top of the pole extending a foot or more above the antenna?
>
>
Typically when a receiver or other radio is destroyed it was NOT because of
a direct strike.  A strike within maybe 100 feet is enough.  There is a
_huge_ EMP field around the strike.  The field will induce large currents
in any nearby conductors.   Even if the strike is to bare Earth many feet
from the antenna the potential of the earth is raised by say 1,000 volts so
now anything connected between ground the power has 1KV across it.





Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Re-radiating a GPS signal...??

[Hal Murray]

hmur...@megapathdsl.net said:
> I think you will just get the position of the receiving antenna for the
> repeater.  It will get the time when the signals arrived at that antenna.

> Consider what happens if you replace the air between the repeater's transmit
>  antenna and the GPS receiver with a chunk of coax.  The key idea is that
> the  signals from each satellite are delayed the same amount with either a
> repeater or coax. 

Argh.  I hate it when I'm thinking one thing and type the opposite.

The GPS-repeater receiver will see the time at the receiving antenna for the 
repeater as delayed by the propagation from repeater to GPS receiver.  You 
get the right answer if you think of that air path as coax.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] Re-radiating a GPS signal...??

[Tom Knox]

It seems to me that the rebroadcast signal will need to be really low to avoid 
interference with the original signal, at that level multipath could be a big 
problem. From my experience fiber is the method of choice commercially for both 
lightning protection and long cable runs. But those systems are really 
expensive unless you are protecting some serious equipment.


Thomas Knox



> To: time-nuts@febo.com
> From: hmur...@megapathdsl.net
> Date: Thu, 12 Apr 2012 12:44:19 -0700
> Subject: Re: [time-nuts] Re-radiating a GPS signal...??
> 
> 
> li...@medesign.ro said:
> > GPS being extremely time-dependent, any delay introduced will affect
> > positioning precision.
> 
> I think you will just get the position of the receiving antenna for the 
> repeater.  It will get the time when the signals arrived at that antenna.
> 
> Consider what happens if you replace the air between the repeater's transmit 
> antenna and the GPS receiver with a chunk of coax.  The key idea is that the 
> signals from each satellite are delayed the same amount with either a 
> repeater or coax.
> 
>   
> 
> 
> 
> 
> 
> -- 
> These are my opinions, not necessarily my employer's.  I hate spam.
> 
> 
> 
> 
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Re: [time-nuts] WWVB relative field strength graph

[paul swed]

I took a look and as it says its relative. Don't think there is a trusted
relationship.
Good to hear you have everything going. I believe outside is important not
so sure huge height much matters at 60Khz. I ran at the 45 level on a tower
for years and have to say 6 foot in the woods seems to operate just as well
given the propagation variation every day.
You may not need it but I have a number of wwvb rcvrs so I built an active
splitter to feed up to 6 units. Essentially single opamp in to 6 buffer
amps. Stupid simple.
Regards
Paul
WB8TSL

On Thu, Apr 12, 2012 at 1:51 PM, Jim Hickstein  wrote:

> Over at 
> http://tf.nist.gov/tf-cgi/**wwvbmonitor_e.cgithere
>  is a "relative field strength" plot for each of the monitoring
> stations.  I'm trying to correlate LaCrosse with my own measurements in St.
> Paul (AGC voltage in my Spectracom 8164) and it's very bothersome that this
> graph has no scale and no origin.  The unit is said to be uV/m.  Does
> anyone here happen to know what the evident top rail value is?  It often
> hits it during the dark-path period.  And the magnitude of a vertical tick?
>  I suppose it's logarithmic.
>
> The 8164 manual says that AGC 2.0V corresponds to 100uV/m at a properly
> oriented antenna.
>
> I got both the 8170 and the 8164 going last night, after finding the other
> 8206 antenna[1], still mounted in the attic of the garage.  So I have one
> outdoors (in the back yard, up 10 feet on a PVC pipe), but with a long and
> maybe lossy feed line, and the other one nearby but indoors.  Today they
> both seem quite happy (AGC 1.3V), even though LaCrosse is "unreadable".
>
> [1] "Engine #3 found on right wing after brief search."
>
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Re: [time-nuts] Best location for a GPS antenna...?

[lists]

I'd suggest getting Dr. Uman's "All About Lightning" as a starter. You could 
read it in an afternoon, so to be correct, the book is all about lightning, but 
it doesn't contain all the world's knowledge. ;-).  It isn't very technical, 
though he has written technical books as well.  

Regarding schemes to prevent lightning hits, they are all controversial. That 
is, scientists argue over the effectiveness. The one I see often in the high 
desert looks like a brush made out of metal fibers.   

I've got to see ground hits in the desert twice. Amazing. The spot hit glows 
yellow, which I presume is sodium ionization. 

--Original Message--
From: Attila Kinali
Sender: time-nuts-boun...@febo.com
To: David McGaw
To: Discussion of precise time and frequency measurement
ReplyTo: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?
Sent: Apr 12, 2012 12:22 PM

On Thu, 12 Apr 2012 15:02:48 -0400
David McGaw  wrote:

> Best would be to have a lightning rod in the vicinity of and above the 
> antenna.  A sharp-pointed rod does not attract lightning, it REPELS it 
> and has a cone of protection under it.  While the effect is not 
> understood, it apparently discharges the surrounding air through corona 
> discharge - the sharper the better.

I'd like to read more on that, do you have any good references?

Attila Kinali
-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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Re: [time-nuts] Re-radiating a GPS signal...??

[Hal Murray]

li...@medesign.ro said:
> GPS being extremely time-dependent, any delay introduced will affect
> positioning precision.

I think you will just get the position of the receiving antenna for the 
repeater.  It will get the time when the signals arrived at that antenna.

Consider what happens if you replace the air between the repeater's transmit 
antenna and the GPS receiver with a chunk of coax.  The key idea is that the 
signals from each satellite are delayed the same amount with either a 
repeater or coax.

  





-- 
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Re: [time-nuts] Best location for a GPS antenna...?

[Chris Albertson]

On Thu, Apr 12, 2012 at 12:02 PM, David McGaw wrote:

> Best would be to have a lightning rod in the vicinity of and above the
> antenna.  A sharp-pointed rod does not attract lightning, it REPELS it and
> has a cone of protection under it.  While the effect is not understood, it
> apparently discharges the surrounding air through corona discharge - the
> sharper the better.
>
>
Yes.  That is why.   Air normally is a decent insulator.  But if it gets
ionized (charged) then it can conduct.  The way lightening works is the air
gets more and more conductive until finally there is a weak path then
current starts  to flow, the current further ionizes the air along the path
allowing even more current to flow which ionized more air and you get a
run-away reaction what a huge current then flows which heats and rarefies
the air which in turn breaks the conductive path.

You can protect yourself by NOT being near that first weak ionized path.
 One way is to firmly ground the air around you so that it remains
un-charged.But how to do that is kind of a black art.

The other way to protect yourself  build a "voltage divider"  just like
you'd make with a pair of resisters.  Current will flow in proportion to
the resistance.  So you wire your roof via a "milliohm resister" to ground
and hope the current will divide and 99.99% of it goes through the large
ground strap (aka milliohm resister)

But as it turns out the ground strap works as both a voltage divider and a
means to ground the air to prevent it from being ionized.

I hope this explains why a lightening rod can both repel lightening and
protect you from a strike.




Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Best location for a GPS antenna...?

[Chris Albertson]

On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt wrote:

> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>
>> What about mounting the antenna on the side of the metal pole, with the
>> top of the pole extending a foot or more above the antenna?
>
>
Typically when a receiver or other radio is destroyed it was NOT because of
a direct strike.  A strike within maybe 100 feet is enough.  There is a
_huge_ EMP field around the strike.  The field will induce large currents
in any nearby conductors.   Even if the strike is to bare Earth many feet
from the antenna the potential of the earth is raised by say 1,000 volts so
now anything connected between ground the power has 1KV across it.





Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Best location for a GPS antenna...?

[Attila Kinali]

On Thu, 12 Apr 2012 15:02:48 -0400
David McGaw  wrote:

> Best would be to have a lightning rod in the vicinity of and above the 
> antenna.  A sharp-pointed rod does not attract lightning, it REPELS it 
> and has a cone of protection under it.  While the effect is not 
> understood, it apparently discharges the surrounding air through corona 
> discharge - the sharper the better.

I'd like to read more on that, do you have any good references?

Attila Kinali
-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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Re: [time-nuts] Best location for a GPS antenna...?

[Attila Kinali]

On Thu, 12 Apr 2012 18:41:43 +0200
b...@lysator.liu.se wrote:

> Rerad-systems are getting controlled in Europe too.
> 
> http://www.etsi.org/deliver/etsi_en/302600_302699/302645/01.01.01_60/en_302645v010101p.pdf
> 
> Any reports on how quick this is going? Where I live, there are rules, but
> not many are aware of them.

Interesting, I thought that repeaters were covered by the standard
frequency regulation: ie they are forbidden (or in long: you are not
allowed to make radiations in a frequency band you are not licensed to
send). Unless of course, these repeaters do not fall under the
"radio devices" category, which then the radiation would be simply EMI :-)

Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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Re: [time-nuts] Best location for a GPS antenna...?

[jmfranke]

Of course the answer depends on what you mean by noticeable extent. I am 
assuming the mast is less than 3' in diameter and the GPS antenna is at 
least a foot away from the mast. I would say for position error larger than 
three feet, no and for timing errors larger than 5 nanoseconds, no. This of 
course assumes the receiver is capable of that accuracy level. If you try to 
go below that, other items in your immediate neighborhood would need to be 
examined.


John  WA4WDL

--
From: "Randy D. Hunt" 
Sent: Thursday, April 12, 2012 2:56 PM
To: "Discussion of precise time and frequency measurement" 


Subject: Re: [time-nuts] Best location for a GPS antenna...?


On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
What about mounting the antenna on the side of the metal pole, with the 
top of the pole extending a foot or more above the antenna?


The idea is to have the lightning bolt strike the pole, but not the 
antenna. The cable shield would need to be insulated from the pole, but 
grounded on entry to the building.


Would the pole disturb the GPS signal to any noticeable extent?

Cheers
Stefan






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Re: [time-nuts] Best location for a GPS antenna...?

[David McGaw]

Best would be to have a lightning rod in the vicinity of and above the 
antenna.  A sharp-pointed rod does not attract lightning, it REPELS it 
and has a cone of protection under it.  While the effect is not 
understood, it apparently discharges the surrounding air through corona 
discharge - the sharper the better.


David N1HAC

On 4/12/12 2:56 PM, Randy D. Hunt wrote:

On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
What about mounting the antenna on the side of the metal pole, with 
the top of the pole extending a foot or more above the antenna?


The idea is to have the lightning bolt strike the pole, but not the 
antenna. The cable shield would need to be insulated from the pole, 
but grounded on entry to the building.


Would the pole disturb the GPS signal to any noticeable extent?

Cheers
Stefan


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I would think that if a lightning bolt hit that close to the antenna, 
it would still cause considerable damage. Think EMP.


Randy
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Re: [time-nuts] Best location for a GPS antenna...?

[Randy D. Hunt]

On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:

What about mounting the antenna on the side of the metal pole, with the top of 
the pole extending a foot or more above the antenna?

The idea is to have the lightning bolt strike the pole, but not the antenna. 
The cable shield would need to be insulated from the pole, but grounded on 
entry to the building.

Would the pole disturb the GPS signal to any noticeable extent?

Cheers
Stefan


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I would think that if a lightning bolt hit that close to the antenna, it 
would still cause considerable damage. Think EMP.


Randy
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Re: [time-nuts] Re-radiating a GPS signal...??

[jmfranke]

Yes, but the propagation times are the times from each satellite antenna 
phase center to the phase center of the receiving antenna. From that point 
forward, the relative time delays are unchanged. It is the same as if one 
was to record the RF signals at the back of the receiving antenna and then 
play the recording into a receiver a week later. The navigation solution 
would give the location of the receiving antenna when the recording was made 
and the displayed time would also correspond to when the signals were 
recorded and be off from the current time by a week.


John  WA4WDL

--
From: "MailLists" 
Sent: Thursday, April 12, 2012 1:33 PM
To: "Discussion of precise time and frequency measurement" 


Subject: Re: [time-nuts] Re-radiating a GPS signal...??

Purely geometrically, the fix solution is computed as the intersection 
point of spheres with the radii determined by the propagation time, 




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[time-nuts] WWVB relative field strength graph

[Jim Hickstein]

Over at http://tf.nist.gov/tf-cgi/wwvbmonitor_e.cgi there is a "relative field 
strength" plot for each of the monitoring stations.  I'm trying to correlate 
LaCrosse with my own measurements in St. Paul (AGC voltage in my Spectracom 
8164) and it's very bothersome that this graph has no scale and no origin.  The 
unit is said to be uV/m.  Does anyone here happen to know what the evident top 
rail value is?  It often hits it during the dark-path period.  And the magnitude 
of a vertical tick?  I suppose it's logarithmic.


The 8164 manual says that AGC 2.0V corresponds to 100uV/m at a properly oriented 
antenna.


I got both the 8170 and the 8164 going last night, after finding the other 8206 
antenna[1], still mounted in the attic of the garage.  So I have one outdoors 
(in the back yard, up 10 feet on a PVC pipe), but with a long and maybe lossy 
feed line, and the other one nearby but indoors.  Today they both seem quite 
happy (AGC 1.3V), even though LaCrosse is "unreadable".


[1] "Engine #3 found on right wing after brief search."

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Re: [time-nuts] Re-radiating a GPS signal...??

[Azelio Boriani]

Timing GPS receivers have the cable delay parameter to account for the
cable delay.

>>added path delays would mostly cancel out
How can delays cancel out?

On Thu, Apr 12, 2012 at 7:33 PM, MailLists  wrote:

> Purely geometrically, the fix solution is computed as the intersection
> point of spheres with the radii determined by the propagation time, and the
> centers by the positions of the satellites (practically not all spheres
> intersect in the same geometrical point, so an average is computed).
> If the GPS Rx would receive simultaneously all satellites, considered
> evenly distributed on a sphere, then the added path delays would mostly
> cancel out - but if only the visible satellites are accounted for, we will
> have an unbalanced system, approximated to an hemispehere, in which the
> horizontal error will be low, as the longer paths cancel mostly out, but
> for the vertical one it's not the case.
>
> Any GPS receiver will exhibit lower vertical precision than the horizontal
> one.
> The same phenomenon, of low precision, and biasing of position is evident
> if just a part of the constellation is used (an obstacle obscures a large
> part of the sky).
>
> The internal delays of the Rx are mostly fixed and known, so they can be
> accounted for, and compensated in the firmware fix solution, but the cable
> length is a variable (depending on the installation) factor, not accounted
> for.
>
>
> On 4/12/2012 7:15 PM, b...@lysator.liu.se wrote:
>
>> Not at all!
>>
>> The (first) receiving antenna defines the position you get out of a long
>> antenna cable or a reradiating system. The delays in LNA, filters, cables,
>> rerad antenna, free air between rerad antenna and final receiving antenna
>> ALL goed into the receiver clock error. This is clear both from a
>> theoretical point, from most standard GPS texts and from practical
>> experience from multiple installations I have used over the years.
>>
>> If you disagree, please provide evidence.
>>
>> --
>>
>>   Björn
>>
>>  Not quite, the delay of the antenna cable is affecting less the
>>> horizontal position (it depends also on the current received
>>> constellation geometry), but mostly the height ASL of the fix point,
>>> prolonging simultaneously all the paths from the satellites with a fixed
>>> value.
>>> Also, the propagation speed in a cable is significantly lower than in
>>> free space - the perceived delay increase is ~1.5 times for usual cables
>>> (~.67 velocity factor), and the computed fix point would have a lower
>>> height ASL than the real one.
>>>
>>> Those relaying systems are merely good for an approximate location fix,
>>> mostly for not loosing the GPS signal in covered areas so that the
>>> reacquire of the real signal is faster, with almost no perceived
>>> discontinuity.
>>>
>>>
>>> On 4/12/2012 6:11 PM, David McGaw wrote:
>>>
 The time/position fix would be from the location of the receiving
 antenna of the repeater, degraded only by noise.

 This should work if both antennas have good back-side rejection
 (choke-rings are particularly good for this but perhaps any good timing
 antenna could meet this), the re-transmitting antenna is close to being
 directly under the receiving antenna, and the system gain is low enough.
 The problem I would see in a room that is not fully shielded is
 interference between the direct and retransmitted signals at the
 receiver under test.

 David N1HAC

 On 4/12/12 10:17 AM, MailLists wrote:

> GPS being extremely time-dependent, any delay introduced will affect
> positioning precision. Also, the signal is too weak for such an
> amplification/echo cancelling signal chain.
> Passive relaying, or using at most a simple amplifier with low enough
> gain, and short signal delay, remain the only feasible concepts.
>
> On 4/12/2012 4:48 PM, Azelio Boriani wrote:
>
>> Passive UHF TV repeaters were in use in Italy too. Nowadays, for the
>> DVB-T
>> TV, active gap-fillers are used instead. Active gap-fillers are
>> same-channel repeaters with the necessary, sophisticated echo
>> suppression
>> technique. We have developed our echo suppression signal processor on
>> a
>> Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS
>> CDMA.
>>
>> On Thu, Apr 12, 2012 at 3:29 PM, Alan
>> Meliawrote:
>>
>>  If the isolation is good and the "clear view" signal is reasonably
>>> strong,
>>> the passive system works well in hangers, metalclad warehouses,
>>> ferry lorry
>>> decks.
>>> The passive system in the UK used to be refered to as the "Matlock
>>> Repeater".
>>>
>>> Alan
>>> G3NYK
>>>
>>> - Original Message -
>>> From: "Michael Baker"
>>> To:
>>> Sent: Thursday, April 12, 2012 2:05 PM
>>> Subject: [time-nuts] Re-radiating a GPS signal...??
>>>
>>>
>>>  Time-nutters--

Re: [time-nuts] Re-radiating a GPS signal...??

[David McGaw]

Since I am used to figuring the cable (and additional propagation) 
delays, I did forget to mention that for timing.  :-)


On the other hand, I would not be using a repeater except for just 
functional testing of a payload system.


David

On 4/12/12 12:15 PM, b...@lysator.liu.se wrote:

Not at all!

The (first) receiving antenna defines the position you get out of a long
antenna cable or a reradiating system. The delays in LNA, filters, cables,
rerad antenna, free air between rerad antenna and final receiving antenna
ALL goed into the receiver clock error. This is clear both from a
theoretical point, from most standard GPS texts and from practical
experience from multiple installations I have used over the years.

If you disagree, please provide evidence.

--

   Björn


Not quite, the delay of the antenna cable is affecting less the
horizontal position (it depends also on the current received
constellation geometry), but mostly the height ASL of the fix point,
prolonging simultaneously all the paths from the satellites with a fixed
value.
Also, the propagation speed in a cable is significantly lower than in
free space - the perceived delay increase is ~1.5 times for usual cables
(~.67 velocity factor), and the computed fix point would have a lower
height ASL than the real one.

Those relaying systems are merely good for an approximate location fix,
mostly for not loosing the GPS signal in covered areas so that the
reacquire of the real signal is faster, with almost no perceived
discontinuity.


On 4/12/2012 6:11 PM, David McGaw wrote:

The time/position fix would be from the location of the receiving
antenna of the repeater, degraded only by noise.

This should work if both antennas have good back-side rejection
(choke-rings are particularly good for this but perhaps any good timing
antenna could meet this), the re-transmitting antenna is close to being
directly under the receiving antenna, and the system gain is low enough.
The problem I would see in a room that is not fully shielded is
interference between the direct and retransmitted signals at the
receiver under test.

David N1HAC

On 4/12/12 10:17 AM, MailLists wrote:

GPS being extremely time-dependent, any delay introduced will affect
positioning precision. Also, the signal is too weak for such an
amplification/echo cancelling signal chain.
Passive relaying, or using at most a simple amplifier with low enough
gain, and short signal delay, remain the only feasible concepts.

On 4/12/2012 4:48 PM, Azelio Boriani wrote:

Passive UHF TV repeaters were in use in Italy too. Nowadays, for the
DVB-T
TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo
suppression
technique. We have developed our echo suppression signal processor on
a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS
CDMA.

On Thu, Apr 12, 2012 at 3:29 PM, Alan
Meliawrote:


If the isolation is good and the "clear view" signal is reasonably
strong,
the passive system works well in hangers, metalclad warehouses,
ferry lorry
decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message -
From: "Michael Baker"
To:
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??



Time-nutters--

So-- How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below. The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station
tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley. I was
told that it worked pretty well.

Mike Baker
--

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Re: [time-nuts] Re-radiating a GPS signal...??

[MailLists]

Purely geometrically, the fix solution is computed as the intersection 
point of spheres with the radii determined by the propagation time, and 
the centers by the positions of the satellites (practically not all 
spheres intersect in the same geometrical point, so an average is computed).
If the GPS Rx would receive simultaneously all satellites, considered 
evenly distributed on a sphere, then the added path delays would mostly 
cancel out - but if only the visible satellites are accounted for, we 
will have an unbalanced system, approximated to an hemispehere, in which 
the horizontal error will be low, as the longer paths cancel mostly out, 
but for the vertical one it's not the case.


Any GPS receiver will exhibit lower vertical precision than the 
horizontal one.
The same phenomenon, of low precision, and biasing of position is 
evident if just a part of the constellation is used (an obstacle 
obscures a large part of the sky).


The internal delays of the Rx are mostly fixed and known, so they can be 
accounted for, and compensated in the firmware fix solution, but the 
cable length is a variable (depending on the installation) factor, not 
accounted for.



On 4/12/2012 7:15 PM, b...@lysator.liu.se wrote:

Not at all!

The (first) receiving antenna defines the position you get out of a long
antenna cable or a reradiating system. The delays in LNA, filters, cables,
rerad antenna, free air between rerad antenna and final receiving antenna
ALL goed into the receiver clock error. This is clear both from a
theoretical point, from most standard GPS texts and from practical
experience from multiple installations I have used over the years.

If you disagree, please provide evidence.

--

   Björn


Not quite, the delay of the antenna cable is affecting less the
horizontal position (it depends also on the current received
constellation geometry), but mostly the height ASL of the fix point,
prolonging simultaneously all the paths from the satellites with a fixed
value.
Also, the propagation speed in a cable is significantly lower than in
free space - the perceived delay increase is ~1.5 times for usual cables
(~.67 velocity factor), and the computed fix point would have a lower
height ASL than the real one.

Those relaying systems are merely good for an approximate location fix,
mostly for not loosing the GPS signal in covered areas so that the
reacquire of the real signal is faster, with almost no perceived
discontinuity.


On 4/12/2012 6:11 PM, David McGaw wrote:

The time/position fix would be from the location of the receiving
antenna of the repeater, degraded only by noise.

This should work if both antennas have good back-side rejection
(choke-rings are particularly good for this but perhaps any good timing
antenna could meet this), the re-transmitting antenna is close to being
directly under the receiving antenna, and the system gain is low enough.
The problem I would see in a room that is not fully shielded is
interference between the direct and retransmitted signals at the
receiver under test.

David N1HAC

On 4/12/12 10:17 AM, MailLists wrote:

GPS being extremely time-dependent, any delay introduced will affect
positioning precision. Also, the signal is too weak for such an
amplification/echo cancelling signal chain.
Passive relaying, or using at most a simple amplifier with low enough
gain, and short signal delay, remain the only feasible concepts.

On 4/12/2012 4:48 PM, Azelio Boriani wrote:

Passive UHF TV repeaters were in use in Italy too. Nowadays, for the
DVB-T
TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo
suppression
technique. We have developed our echo suppression signal processor on
a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS
CDMA.

On Thu, Apr 12, 2012 at 3:29 PM, Alan
Meliawrote:


If the isolation is good and the "clear view" signal is reasonably
strong,
the passive system works well in hangers, metalclad warehouses,
ferry lorry
decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message -
From: "Michael Baker"
To:
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??



Time-nutters--

So-- How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below. The passive repeater consisted of an ar

Re: [time-nuts] Thoughts on lightning protection measures....

[Chris Albertson]

On Thu, Apr 12, 2012 at 7:22 AM, Bob Camp  wrote:
> Hi
>
> Is your house hit multiple times per year now? If so, I'd suggest that's the
> issue that needs to be solved. If not, then mount the antenna lower than the
> peak of the house and move on.

Did you not read the first post in this thread?   He said it is common
to have buried cables dangaged by near by strikes.   I assume "under
ground" is not the tallest thing around

The point about lightening is NOT if the object is directly struct.
There is nothing you can do in that case, a  "ightening arrestor" is
kind of a joke to a bolt that just jumped across a miles long air gap.

What destroyed the underground cable is the EMP pulse from a strike
that was 100 feet away.  EMP induced a current and the current was
greater then the current carrying ability of the conductor.


Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Best location for a GPS antenna...?

[Bob Camp]

Hi

Some of the people posting to the thread seem to be concerned about the
house burning down because they put up a GPS antenna...

Receivers can die from a lot of causes. A TBolt like GPS being killed by
input overload from a strike 100 feet away would not be very high on my list
of likely problems.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: Thursday, April 12, 2012 12:50 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?

On Wed, Apr 11, 2012 at 3:08 PM, Bob Camp  wrote:
> Hi
>
> If the antenna is no higher than your house, it's no more likely to get
hit than the house.
> If it's higher than the house by a few feet, the increase in hit
probability is vanishingly small.

Antenna do not have to be directly hit to destroy the receiver.  Let's
say that something 100 feet away is hit.  The nearby strike is
thousands of amps of current in a brief pulse.  What you have is
a strong electromagnetic field pulse.  This will induce current in any
nearby conductor, including your antenna mast, power lines, phone
lines and even the copper traces on a PCB.   The effects vary based on
the geometry.One does not even worry about a direct hit.  It is
rare and if it happens your equipment is vaporized.  But near hits
happen all the time you can expect them and they are mostly the cause
of damaged equipment and it is actually posable to protect against a
nearby hit.

Think of lightening like a 1,000 pound bomb.  If one falls from the
sky on a city and hits you on the head you are dead.  But most of the
people effected by the bomb did NOT get hit on the head and were
varying distances from it and for most of them various protection
measures can be very effective.

Redondo Beach, California

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Re: [time-nuts] Best location for a GPS antenna...?

[Attila Kinali]

On Thu, 12 Apr 2012 12:41:51 -0400
"Bob Camp"  wrote:

> GPS is pretty close to the noise "as received". A fully passive system with
> significant cable loss and low / no gain antennas does not sound like it's
> going to do a very good job.

GPS is pretty much under the noise "as received" :-)

At least in urban regions with lots of noise around, the GPS signal is
burried deep within the noise. In rural areas the signal of a single
satelite is still below thermal noise. The combined signal of all satelites
can be above noise though.

Attila Kinali
-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Thoughts on lightning protection measures....

[Antonio Amandio Sanches de Magalhaes]

Fortunately, it seems that lightning is not as frequent in high
northern and southern latitudes as is in tropical regions.

I was told about a story of a group of Swedish scientists
involved in thunderstorm studies, having built a little lab
in the village with the best reputation of high probability
of lightning, receiving after several years without events
a delegation of the residents "very grateful because after
the lab installation there was no more lightning".

Best regards,
Antonio
CT1TE

Em 2012-04-12 17:20, Said Jackson escreveu:

One interesting fact: frozen ground is a bad conductor.

The ground potential around your house may go up many 1000s of volts
even with just a proximity strike, while the power feed stays down,
blowing up anything connected to "ground". Thus the special Nordig
surge protection requirements for TV receivers in northern European
countries..





On Apr 12, 2012, at 6:58, Jim Lux  wrote:


On 4/12/12 6:22 AM, Michael Baker wrote:

Time-nutters--

Around here (N. Central Flori-DUH) it is not uncommon for
near-by lightning strikes to damage underground cables and
wiring. This is why buried wiring to things like driveway
gate-openers are often placed in conduit rather than done
with direct-burial wiring so that if lightning damages the
wiring a new cable can be pulled through the conduit without
having to re-dig the burial trench.

Some years ago I had occasion to hold some long discussions
with Martin Uman, one of the worlds most distinguished and
eminent lightning researchers. He commented that even with
the most extraordinary and costly efforts to install protection
measures, that-- sooner or later-- there was a good chance that
lightning would find a way to damage things.




Dr. Uman (and his colleague Dr. Rakov) probably know about lightning 
and effects than any other humans alive.   He's making an excellent 
point: at some point, the cost to replace the gear (or the cost of 
being "off the air") is smaller than the cost of the protection 
scheme.


Sometimes, you're better off having a sacrificial element, and a 
spare in the closet for speedy repair.




His lightning research laboratory was located here in
N.Central Florida because it is in the heart of the most
dense strike area in N. America.




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Re: [time-nuts] Thoughts on lightning protection measures....

[Attila Kinali]

On Thu, 12 Apr 2012 09:20:37 -0700
Said Jackson  wrote:

> One interesting fact: frozen ground is a bad conductor.
> 
> The ground potential around your house may go up many 1000s of volts
> even with just a proximity strike, while the power feed stays down,
> blowing up anything connected to "ground". Thus the special Nordig surge
> protection requirements for TV receivers in northern European countries..

Hmm? That sounds interesting. In switzerland, and AFAIK in most european
countries, power feeds have to be grounded at the entry of the house
(ie the neutral conductor is grounded). This should protect the electrical
equipment from such ground jumps as you discribe. Or do i miss something?

Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Temex LPFRS-01

[Azelio Boriani]

Interesting... have to check my LPFRS now: only tested for the lock
indicator when received and then put aside to complete first the
"discipliner".

On Thu, Apr 12, 2012 at 5:00 PM, MailLists  wrote:

> Well, the saga continues...
> A replacement part (for which a thorough check was specifically asked) has
> arrived. It boasts a "Checked OK" written with a marker pen on the label.
> Promising...
> With high expectations, the necessary connections were made, power
> applied, and after warming up it locks at precisely 9.999,817,1 MHz...
> bummer.
> Sometimes, for (yet) unknown reasons, it unlocks again, and, if the
> frequency adjustment trend is upwards, it locks again at ~10.000.000 MHz.
> The lock signal is active even at higher temperatures - that's quite better
> than the first unit, but after a power cycle the story repeats... mostly
> the wrong frequency comes out, but, on the brighter side, it's locked.
>
>
> On 3/18/2012 10:26 AM, MailLists wrote:
>
>> Yes...
>> Thank you, and the others, for the suggestions for cleaning/reviving the
>> unit, but I can't recommend to my friend to keep a pile of rust (if
>> water damage really is the problem) advertised as an used working item.
>>
>> Regards,
>> bbg
>>
>>
>> On 3/17/2012 4:10 PM, Azelio Boriani wrote:
>>
>>> LPFRS from fluke.l? OK, then open it up and clean it, the LPFRS from
>>> fluke.l suffers from high humidity/water immersion and usually are very
>>> rusty inside. I have received one that was very bad but after cleaning
>>> with
>>> tetrachloroethylene (translated with google) it is working properly,
>>> maybe
>>> it will fail soon but now works. I complained with fluke.l and he
>>> refunded
>>> me without asking to ship back the LPFRS.
>>> TIP: handle with extreme care an opened LPFRS, there is a flexible PCB
>>> that
>>> holds the DB9 connector that can tear in the corners.
>>>
>>> On Sat, Mar 17, 2012 at 10:59 AM, MailLists wrote:
>>>
>>>  Hello all,

 a friend purchased from the bay a in the LPRO configuration.
 After
 some problems encountered during the first power ups, he asked for
 help -
 I'm passing the questions further...
 After about 9 minutes of warm-up from room temperature (22°C) the lock
 signal goes low, but after a short time starts to switch low/high with
 decreasing low periods, until it remains high with short low pulses,
 spaced
 at about 2 seconds. After power-down, and sufficient cooling time, the
 cycle repeats.
 First step was to reapply the thermal interface to the integrated Al
 radiator, which helped a bit, the time during which the unit is locked
 growing slightly.
 Next step was forced cooling, which helped more, so the lock loss
 could be
 attributed with high probability to elevated operating temperatures. The
 temperature of the base plate (integrated Al radiator) at which lock
 gets
 lost is about 40°C, so for a reasonable operation it should not pass
 about
 36°C, at which the power consumption raises to about 17W. That also
 means
 that for a 1°C/W heat sinking - obtainable with a larger passive HS or
 active cooling - operation above 30°C ambient gets practically
 impossible
 (except refrigeration, Peltier, etc.).

 Any further help or suggestions are welcome.

 Regards,
 bbg

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Re: [time-nuts] Best location for a GPS antenna...?

[Chris Albertson]

On Wed, Apr 11, 2012 at 3:08 PM, Bob Camp  wrote:
> Hi
>
> If the antenna is no higher than your house, it's no more likely to get hit 
> than the house.
> If it's higher than the house by a few feet, the increase in hit probability 
> is vanishingly small.

Antenna do not have to be directly hit to destroy the receiver.  Let's
say that something 100 feet away is hit.  The nearby strike is
thousands of amps of current in a brief pulse.  What you have is
a strong electromagnetic field pulse.  This will induce current in any
nearby conductor, including your antenna mast, power lines, phone
lines and even the copper traces on a PCB.   The effects vary based on
the geometry.One does not even worry about a direct hit.  It is
rare and if it happens your equipment is vaporized.  But near hits
happen all the time you can expect them and they are mostly the cause
of damaged equipment and it is actually posable to protect against a
nearby hit.

Think of lightening like a 1,000 pound bomb.  If one falls from the
sky on a city and hits you on the head you are dead.  But most of the
people effected by the bomb did NOT get hit on the head and were
varying distances from it and for most of them various protection
measures can be very effective.

Redondo Beach, California

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Re: [time-nuts] Best location for a GPS antenna...?

[bg]

Rerad-systems are getting controlled in Europe too.

http://www.etsi.org/deliver/etsi_en/302600_302699/302645/01.01.01_60/en_302645v010101p.pdf

Any reports on how quick this is going? Where I live, there are rules, but
not many are aware of them.
--

   Björn

> You must read:
> http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html
>
> Which discusses a FCC complaint with Navtech for selling GPS reradiating
kits.
> An exert is presented below:
>
>
>  ``Please note: re-radiation kits are currently only
>  available for purchase to International Customers and in
>  cases where the U.S. Government is the end user.''


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Re: [time-nuts] Best location for a GPS antenna...?

[Bob Camp]

Hi

GPS is pretty close to the noise "as received". A fully passive system with
significant cable loss and low / no gain antennas does not sound like it's
going to do a very good job.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Jim Lux
Sent: Thursday, April 12, 2012 9:52 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Best location for a GPS antenna...?

On 4/12/12 2:09 AM, Rob Kimberley wrote:
> There are commercial "re-radiators" for GPS.  I found these on Google:
>
> 
> 
>
>
> One of my old suppliers in the UK was marketing a range of these, but I
seem
> to remember some problem in getting approval in the UK, and they had to
drop
> them. Things may have changed as this was a few years ago.
>
Interestingly I've just been looking into this...  Why would you need 
anything special to reradiate.. It's not like you need a particular 
antenna pattern or constant gain or something. What about something like 
a fat monopole against a ground plane, with a attenuator at the feed to 
provide a good terminating impedance for the LNA/Line driver.

If it's L1 only, you don't even need particularly wide bandwidth (<1%)


Yes, I've seen setups at JPL where they reradiate with D&M or Ashtech 
chokering antennas (or even helibowls), but that might be because we've 
got a bunch of them sitting around, so why not use it.


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Re: [time-nuts] Thoughts on lightning protection measures....

[Bob Camp]

Hi

The lightning hit is both a great big voltage and a wallop of current. The
voltage is the thing many people get worried about. Almost all of the damage
I've had has come from current induced into near by conductors and similar
magnetic field issues.

That said, the voltage spike has likely jumped several hundred feet to get
into the vicinity of your house. Hopping from this to that while trying to
run through the house is trivial compared to the distance it's already
traveled. 

There are indeed ways to take care of this stuff. Some systems are set up
for a "how many strikes per hour" type of operation. They do indeed run
properly in a high hit rate environment. You do *not* want to foot the cost
for an installation like that. Having the (insured) house burn down is much
cheaper 

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of MailLists
Sent: Thursday, April 12, 2012 11:22 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thoughts on lightning protection measures

You're right, but it's highly depending on the used construction 
materials... The building I live in, is quite like a Faraday cage - 
reinforced concrete. Even higher frequency radio signals have a tough 
time entering, mostly through the windows.
What I wanted to underline is that, even if the house would be build 
like a Faraday cage, any conductor from the outside represents a 
potential dangerous ingress path.

Of course, the generated fields would affect any sensitive equipment, 
but with the low impedance path of an antenna cable, even the less 
sensitive ones could suffer catastrophic failure. Not to neglect are all 
the other conductors entering from the outside - power lines, metallic 
pipes, etc.
"Full protection" is quite difficult, almost impossible, to obtain, but 
an antenna cable is the preferred path.


On 4/12/2012 6:02 PM, Attila Kinali wrote:
> On Thu, 12 Apr 2012 17:39:57 +0300
> MailLists  wrote:
>
>> Regarding the TBs, even if they are the only ones directly connected to
>> the antenna, the cable is already punching through the house Faraday
>> cage, and chances are quite high that the lightning discharge won't stop
>> at them.
>
> A house isnt a faraday cage. Not by far. Unless you live in a box made out
> of solid 5mm steal plates.
>
> If a lightning hits your house directly and is going down the lightning
> rod down into earth there is a good chance that the electric and magnetic
> fields you have in the house will fry sensitive electronic equipment
>
>
>   Attila Kinali

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Re: [time-nuts] Best location for a GPS antenna...?

[jmfranke]

I meant to type GPS repeaters not GPS receivers

John  WA4WDL

--
From: "jmfranke" 
Sent: Thursday, April 12, 2012 12:28 PM
To: 
Subject: Re: [time-nuts] Best location for a GPS antenna...?


You must read:
http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html

Which discusses a FCC complaint with Navtech for selling GPS receivers.
An exert is presented below:


``Please note: re-radiation kits are currently only
available for purchase to International Customers and in
cases where the U.S. Government is the end user.''


Pursuant to Section 15.201(b) of the Rules, 47 C.F.R. §
15.201(b), intentional radiators must be authorized in accordance
with the FCC's certification procedures prior to the initiation
of marketing in the United States.  However, GPS re-radiators
operate within the restricted frequency bands listed in Section
15.205(a) of the Rules, 47 C.F.R. § 15.205(a).4  Thus, GPS re-
radiators cannot comply with the FCC's technical standards and
therefore cannot be certificated or marketed for use by the
general public or non-federal government entities.  Accordingly,
it appears that Navtech has violated Section 302(b) of the Act
and Sections 2.803 and 15.205(a) of the Rules by marketing in the
United States radio frequency devices that are not eligible to
receive a grant of certification.

You should be aware that the Commission has recently
addressed a Petition for Rulemaking and a Request for Waiver
seeking amendment of FCC regulations to permit the marketing of
GPS re-radiation kits.5   By Order released July 6, 2005, the
FCC's Office of Engineering and Technology (OET) denied the
Petition for Rulemaking and Request for Waiver.6  OET noted that
the Petition raised significant issues that needed further study
and therefore did not warrant consideration at the time.
Accordingly, Navtech is reminded that at this time GPS re-
radiating devices are not permitted to be sold to the general
public or to state or local governments.

John  WA4WDL



--
From: "Jim Lux" 
Sent: Thursday, April 12, 2012 9:51 AM
To: 
Subject: Re: [time-nuts] Best location for a GPS antenna...?


On 4/12/12 2:09 AM, Rob Kimberley wrote:

There are commercial "re-radiators" for GPS.  I found these on Google:





One of my old suppliers in the UK was marketing a range of these, but I 
seem
to remember some problem in getting approval in the UK, and they had to 
drop

them. Things may have changed as this was a few years ago.





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and follow the instructions there.




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Re: [time-nuts] Re-radiating a GPS signal...??

[jmfranke]

You must read:
http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html

Which discusses a FCC complaint with Navtech for selling GPS repeaters.
An exert is presented below:


``Please note: re-radiation kits are currently only
available for purchase to International Customers and in
cases where the U.S. Government is the end user.''


Pursuant to Section 15.201(b) of the Rules, 47 C.F.R. §
15.201(b), intentional radiators must be authorized in accordance
with the FCC's certification procedures prior to the initiation
of marketing in the United States.  However, GPS re-radiators
operate within the restricted frequency bands listed in Section
15.205(a) of the Rules, 47 C.F.R. § 15.205(a).4  Thus, GPS re-
radiators cannot comply with the FCC's technical standards and
therefore cannot be certificated or marketed for use by the
general public or non-federal government entities.  Accordingly,
it appears that Navtech has violated Section 302(b) of the Act
and Sections 2.803 and 15.205(a) of the Rules by marketing in the
United States radio frequency devices that are not eligible to
receive a grant of certification.

You should be aware that the Commission has recently
addressed a Petition for Rulemaking and a Request for Waiver
seeking amendment of FCC regulations to permit the marketing of
GPS re-radiation kits.5   By Order released July 6, 2005, the
FCC's Office of Engineering and Technology (OET) denied the
Petition for Rulemaking and Request for Waiver.6  OET noted that
the Petition raised significant issues that needed further study
and therefore did not warrant consideration at the time.
Accordingly, Navtech is reminded that at this time GPS re-
radiating devices are not permitted to be sold to the general
public or to state or local governments.

John  WA4WDL






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Re: [time-nuts] Best location for a GPS antenna...?

[jmfranke]

You must read:
http://transition.fcc.gov/eb/Orders/2005/DA-05-2998A1.html

Which discusses a FCC complaint with Navtech for selling GPS receivers.
An exert is presented below:


``Please note: re-radiation kits are currently only
available for purchase to International Customers and in
cases where the U.S. Government is the end user.''


Pursuant to Section 15.201(b) of the Rules, 47 C.F.R. §
15.201(b), intentional radiators must be authorized in accordance
with the FCC's certification procedures prior to the initiation
of marketing in the United States.  However, GPS re-radiators
operate within the restricted frequency bands listed in Section
15.205(a) of the Rules, 47 C.F.R. § 15.205(a).4  Thus, GPS re-
radiators cannot comply with the FCC's technical standards and
therefore cannot be certificated or marketed for use by the
general public or non-federal government entities.  Accordingly,
it appears that Navtech has violated Section 302(b) of the Act
and Sections 2.803 and 15.205(a) of the Rules by marketing in the
United States radio frequency devices that are not eligible to
receive a grant of certification.

You should be aware that the Commission has recently
addressed a Petition for Rulemaking and a Request for Waiver
seeking amendment of FCC regulations to permit the marketing of
GPS re-radiation kits.5   By Order released July 6, 2005, the
FCC's Office of Engineering and Technology (OET) denied the
Petition for Rulemaking and Request for Waiver.6  OET noted that
the Petition raised significant issues that needed further study
and therefore did not warrant consideration at the time.
Accordingly, Navtech is reminded that at this time GPS re-
radiating devices are not permitted to be sold to the general
public or to state or local governments.

John  WA4WDL



--
From: "Jim Lux" 
Sent: Thursday, April 12, 2012 9:51 AM
To: 
Subject: Re: [time-nuts] Best location for a GPS antenna...?


On 4/12/12 2:09 AM, Rob Kimberley wrote:

There are commercial "re-radiators" for GPS.  I found these on Google:





One of my old suppliers in the UK was marketing a range of these, but I 
seem
to remember some problem in getting approval in the UK, and they had to 
drop

them. Things may have changed as this was a few years ago.





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Re: [time-nuts] Thoughts on lightning protection measures....

[Said Jackson]

One interesting fact: frozen ground is a bad conductor.

The ground potential around your house may go up many 1000s of volts even with 
just a proximity strike, while the power feed stays down, blowing up anything 
connected to "ground". Thus the special Nordig surge protection requirements 
for TV receivers in northern European countries..





On Apr 12, 2012, at 6:58, Jim Lux  wrote:

> On 4/12/12 6:22 AM, Michael Baker wrote:
>> Time-nutters--
>> 
>> Around here (N. Central Flori-DUH) it is not uncommon for
>> near-by lightning strikes to damage underground cables and
>> wiring. This is why buried wiring to things like driveway
>> gate-openers are often placed in conduit rather than done
>> with direct-burial wiring so that if lightning damages the
>> wiring a new cable can be pulled through the conduit without
>> having to re-dig the burial trench.
>> 
>> Some years ago I had occasion to hold some long discussions
>> with Martin Uman, one of the worlds most distinguished and
>> eminent lightning researchers. He commented that even with
>> the most extraordinary and costly efforts to install protection
>> measures, that-- sooner or later-- there was a good chance that
>> lightning would find a way to damage things.
>> 
> 
> 
> Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and 
> effects than any other humans alive.   He's making an excellent point: at 
> some point, the cost to replace the gear (or the cost of being "off the air") 
> is smaller than the cost of the protection scheme.
> 
> Sometimes, you're better off having a sacrificial element, and a spare in the 
> closet for speedy repair.
> 
> 
>> His lightning research laboratory was located here in
>> N.Central Florida because it is in the heart of the most
>> dense strike area in N. America.
> 
> 
> 
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Re: [time-nuts] Re-radiating a GPS signal...??

[jmfranke]

Delay of the complete ensemble of signals results in a time shift much like 
the addition of cable between the antenna and receiver. The position 
solution will be the location of the first receiving antenna.


John  WA4WDL

--
From: "MailLists" 
Sent: Thursday, April 12, 2012 10:17 AM
To: "Discussion of precise time and frequency measurement" 


Subject: Re: [time-nuts] Re-radiating a GPS signal...??

GPS being extremely time-dependent, any delay introduced will affect 
positioning precision. 




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Re: [time-nuts] Re-radiating a GPS signal...??

[bg]

Not at all!

The (first) receiving antenna defines the position you get out of a long
antenna cable or a reradiating system. The delays in LNA, filters, cables,
rerad antenna, free air between rerad antenna and final receiving antenna
ALL goed into the receiver clock error. This is clear both from a
theoretical point, from most standard GPS texts and from practical
experience from multiple installations I have used over the years.

If you disagree, please provide evidence.

--

  Björn

> Not quite, the delay of the antenna cable is affecting less the
> horizontal position (it depends also on the current received
> constellation geometry), but mostly the height ASL of the fix point,
> prolonging simultaneously all the paths from the satellites with a fixed
> value.
> Also, the propagation speed in a cable is significantly lower than in
> free space - the perceived delay increase is ~1.5 times for usual cables
> (~.67 velocity factor), and the computed fix point would have a lower
> height ASL than the real one.
>
> Those relaying systems are merely good for an approximate location fix,
> mostly for not loosing the GPS signal in covered areas so that the
> reacquire of the real signal is faster, with almost no perceived
> discontinuity.
>
>
> On 4/12/2012 6:11 PM, David McGaw wrote:
>> The time/position fix would be from the location of the receiving
>> antenna of the repeater, degraded only by noise.
>>
>> This should work if both antennas have good back-side rejection
>> (choke-rings are particularly good for this but perhaps any good timing
>> antenna could meet this), the re-transmitting antenna is close to being
>> directly under the receiving antenna, and the system gain is low enough.
>> The problem I would see in a room that is not fully shielded is
>> interference between the direct and retransmitted signals at the
>> receiver under test.
>>
>> David N1HAC
>>
>> On 4/12/12 10:17 AM, MailLists wrote:
>>> GPS being extremely time-dependent, any delay introduced will affect
>>> positioning precision. Also, the signal is too weak for such an
>>> amplification/echo cancelling signal chain.
>>> Passive relaying, or using at most a simple amplifier with low enough
>>> gain, and short signal delay, remain the only feasible concepts.
>>>
>>> On 4/12/2012 4:48 PM, Azelio Boriani wrote:
 Passive UHF TV repeaters were in use in Italy too. Nowadays, for the
 DVB-T
 TV, active gap-fillers are used instead. Active gap-fillers are
 same-channel repeaters with the necessary, sophisticated echo
 suppression
 technique. We have developed our echo suppression signal processor on
 a
 Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS
 CDMA.

 On Thu, Apr 12, 2012 at 3:29 PM, Alan
 Meliawrote:

> If the isolation is good and the "clear view" signal is reasonably
> strong,
> the passive system works well in hangers, metalclad warehouses,
> ferry lorry
> decks.
> The passive system in the UK used to be refered to as the "Matlock
> Repeater".
>
> Alan
> G3NYK
>
> - Original Message -
> From: "Michael Baker"
> To:
> Sent: Thursday, April 12, 2012 2:05 PM
> Subject: [time-nuts] Re-radiating a GPS signal...??
>
>
>> Time-nutters--
>>
>> So-- How do GPS signal re-radiators work?
>>
>> How do you place a GPS antenna on top of a building,
>> pick up the signal with an LNA, amplify it to re-transmit
>> on an inside antenna without the amplified re-transmitted
>> signal getting back into the roof-top receiving antenna?
>>
>> I can see circumstances where a huge metal building
>> (aircraft hangar?) might provide enough isolation to
>> prevent problems, but in many cases I wonder about it...
>> 
>>
>> As an aside note-- I recall seeing, many years ago, a totally
>> passive TV signal repeater on top of a tall hill in mountainous
>> territory relaying a TV station signal to some homes in a valley
>> just below. The passive repeater consisted of an array of
>> high-gain UHF yagis pointing to the 40 mile distant TV station
>> tower.
>> The yagi array was coupled to another set of high-gain yagi
>> antennas pointing down to the homesites in the valley. I was
>> told that it worked pretty well.
>>
>> Mike Baker
>> --
>>
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>
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 _

Re: [time-nuts] Re-radiating a GPS signal...??

[Said Jackson]

David,

That is correct, the signal is delayed by at least the run length as well. We 
had to tweak the ublox parameters on our GPSDOs for a particular data center 
application that used a re-radiator to make it work as the default ublox 
parameters would get the unit confused due to residual multipath etc.

This is the type of obscure real-world firmware fine-tuning that separates the 
boys from the men...
One may never need it, but it's good to know its there.

Bye,
Said



On Apr 12, 2012, at 8:11, David McGaw  wrote:

> The time/position fix would be from the location of the receiving antenna of 
> the repeater, degraded only by noise.
> 
> This should work if both antennas have good back-side rejection (choke-rings 
> are particularly good for this but perhaps any good timing antenna could meet 
> this), the re-transmitting antenna is close to being directly under the 
> receiving antenna, and the system gain is low enough.  The problem I would 
> see in a room that is not fully shielded is interference between the direct 
> and retransmitted signals at the receiver under test.
> 
> David N1HAC
> 
> On 4/12/12 10:17 AM, MailLists wrote:
>> GPS being extremely time-dependent, any delay introduced will affect 
>> positioning precision. Also, the signal is too weak for such an 
>> amplification/echo cancelling signal chain.
>> Passive relaying, or using at most a simple amplifier with low enough gain, 
>> and short signal delay, remain the only feasible concepts.
>> 
>> On 4/12/2012 4:48 PM, Azelio Boriani wrote:
>>> Passive UHF TV repeaters were in use in Italy too. Nowadays, for the DVB-T
>>> TV, active gap-fillers are used instead. Active gap-fillers are
>>> same-channel repeaters with the necessary, sophisticated echo suppression
>>> technique. We have developed our echo suppression signal processor on a
>>> Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS CDMA.
>>> 
>>> On Thu, Apr 12, 2012 at 3:29 PM, Alan Meliawrote:
>>> 
 If the isolation is good and the "clear view" signal is reasonably strong,
 the passive system works well in hangers, metalclad warehouses, ferry lorry
 decks.
 The passive system in the UK used to be refered to as the "Matlock
 Repeater".
 
 Alan
 G3NYK
 
 - Original Message -
 From: "Michael Baker"
 To:
 Sent: Thursday, April 12, 2012 2:05 PM
 Subject: [time-nuts] Re-radiating a GPS signal...??
 
 
> Time-nutters--
> 
> So--  How do GPS signal re-radiators work?
> 
> How do you place a GPS antenna on top of a building,
> pick up the signal with an LNA, amplify it to re-transmit
> on an inside antenna without the amplified re-transmitted
> signal getting back into the roof-top receiving antenna?
> 
> I can see circumstances where a huge metal building
> (aircraft hangar?) might provide enough isolation to
> prevent problems, but in many cases I wonder about it...
> 
> 
> As an aside note-- I recall seeing, many years ago, a totally
> passive TV signal repeater on top of a tall hill in mountainous
> territory relaying a TV station signal to some homes in a valley
> just below.  The passive repeater consisted of an array of
> high-gain UHF yagis pointing to the 40 mile distant TV station tower.
> The yagi array was coupled to another set of high-gain yagi
> antennas pointing down to the homesites in the valley.  I was
> told that it worked pretty well.
> 
> Mike Baker
> --
> 
> ___
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 ___
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 To unsubscribe, go to
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Re: [time-nuts] Re-radiating a GPS signal...??

[MailLists]

Not quite, the delay of the antenna cable is affecting less the 
horizontal position (it depends also on the current received 
constellation geometry), but mostly the height ASL of the fix point, 
prolonging simultaneously all the paths from the satellites with a fixed 
value.
Also, the propagation speed in a cable is significantly lower than in 
free space - the perceived delay increase is ~1.5 times for usual cables 
(~.67 velocity factor), and the computed fix point would have a lower 
height ASL than the real one.


Those relaying systems are merely good for an approximate location fix, 
mostly for not loosing the GPS signal in covered areas so that the 
reacquire of the real signal is faster, with almost no perceived 
discontinuity.



On 4/12/2012 6:11 PM, David McGaw wrote:

The time/position fix would be from the location of the receiving
antenna of the repeater, degraded only by noise.

This should work if both antennas have good back-side rejection
(choke-rings are particularly good for this but perhaps any good timing
antenna could meet this), the re-transmitting antenna is close to being
directly under the receiving antenna, and the system gain is low enough.
The problem I would see in a room that is not fully shielded is
interference between the direct and retransmitted signals at the
receiver under test.

David N1HAC

On 4/12/12 10:17 AM, MailLists wrote:

GPS being extremely time-dependent, any delay introduced will affect
positioning precision. Also, the signal is too weak for such an
amplification/echo cancelling signal chain.
Passive relaying, or using at most a simple amplifier with low enough
gain, and short signal delay, remain the only feasible concepts.

On 4/12/2012 4:48 PM, Azelio Boriani wrote:

Passive UHF TV repeaters were in use in Italy too. Nowadays, for the
DVB-T
TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo
suppression
technique. We have developed our echo suppression signal processor on a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS
CDMA.

On Thu, Apr 12, 2012 at 3:29 PM, Alan
Meliawrote:


If the isolation is good and the "clear view" signal is reasonably
strong,
the passive system works well in hangers, metalclad warehouses,
ferry lorry
decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message -
From: "Michael Baker"
To:
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??



Time-nutters--

So-- How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below. The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley. I was
told that it worked pretty well.

Mike Baker
--

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Re: [time-nuts] Re-radiating a GPS signal...??

[jmfranke]

David's comment on the direct and retransmitted signals is right on point. 
You are creating a multipath environment with increased signal strength and 
matching polarization. Even with no amplification between the antennas, you 
are generating multipath signals for you and your neighbors.


Advocating signal repeaters is very dangerous. With out proper bandpass 
filtering and path isolation you are inviting trouble from feedback 
oscillation, both in-band and out of band. You may not even be aware of out 
of band effects. If not done properly, including taking in account seasonal 
variation of vegetation, possible effects of someone moving lawn furniture 
around or even vehicular motion changing the feedback path, the results 
could be disastrous. You could be the owner of an intermittent jammer, 
interfere with GPS and/or other signals, and possibly receive a visit from 
the authorities. Look at the problems that where caused by oscillating TV 
peamplifiers radiating from a marina on the west coast. Retransmitting with 
a different output frequency is a different issue and may be a better 
approach.


John  WA4WDL

--
From: "David McGaw" 
Sent: Thursday, April 12, 2012 11:11 AM
To: "Discussion of precise time and frequency measurement" 


Subject: Re: [time-nuts] Re-radiating a GPS signal...??

The time/position fix would be from the location of the receiving antenna 
of the repeater, degraded only by noise.


This should work if both antennas have good back-side rejection 
(choke-rings are particularly good for this but perhaps any good timing 
antenna could meet this), the re-transmitting antenna is close to being 
directly under the receiving antenna, and the system gain is low enough. 
The problem I would see in a room that is not fully shielded is 
interference between the direct and retransmitted signals at the receiver 
under test.


David N1HAC

On 4/12/12 10:17 AM, MailLists wrote:
GPS being extremely time-dependent, any delay introduced will affect 
positioning precision. Also, the signal is too weak for such an 
amplification/echo cancelling signal chain.
Passive relaying, or using at most a simple amplifier with low enough 
gain, and short signal delay, remain the only feasible concepts.


On 4/12/2012 4:48 PM, Azelio Boriani wrote:
Passive UHF TV repeaters were in use in Italy too. Nowadays, for the 
DVB-T

TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo 
suppression

technique. We have developed our echo suppression signal processor on a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS 
CDMA.


On Thu, Apr 12, 2012 at 3:29 PM, Alan 
Meliawrote:


If the isolation is good and the "clear view" signal is reasonably 
strong,
the passive system works well in hangers, metalclad warehouses, ferry 
lorry

decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message -
From: "Michael Baker"
To:
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??



Time-nutters--

So--  How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below.  The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley.  I was
told that it worked pretty well.

Mike Baker
--

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Re: [time-nuts] Thoughts on lightning protection measures....

[MailLists]

You're right, but it's highly depending on the used construction 
materials... The building I live in, is quite like a Faraday cage - 
reinforced concrete. Even higher frequency radio signals have a tough 
time entering, mostly through the windows.
What I wanted to underline is that, even if the house would be build 
like a Faraday cage, any conductor from the outside represents a 
potential dangerous ingress path.


Of course, the generated fields would affect any sensitive equipment, 
but with the low impedance path of an antenna cable, even the less 
sensitive ones could suffer catastrophic failure. Not to neglect are all 
the other conductors entering from the outside - power lines, metallic 
pipes, etc.
"Full protection" is quite difficult, almost impossible, to obtain, but 
an antenna cable is the preferred path.



On 4/12/2012 6:02 PM, Attila Kinali wrote:

On Thu, 12 Apr 2012 17:39:57 +0300
MailLists  wrote:


Regarding the TBs, even if they are the only ones directly connected to
the antenna, the cable is already punching through the house Faraday
cage, and chances are quite high that the lightning discharge won't stop
at them.


A house isnt a faraday cage. Not by far. Unless you live in a box made out
of solid 5mm steal plates.

If a lightning hits your house directly and is going down the lightning
rod down into earth there is a good chance that the electric and magnetic
fields you have in the house will fry sensitive electronic equipment


Attila Kinali


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Re: [time-nuts] Re-radiating a GPS signal...??

[David McGaw]

The time/position fix would be from the location of the receiving 
antenna of the repeater, degraded only by noise.


This should work if both antennas have good back-side rejection 
(choke-rings are particularly good for this but perhaps any good timing 
antenna could meet this), the re-transmitting antenna is close to being 
directly under the receiving antenna, and the system gain is low 
enough.  The problem I would see in a room that is not fully shielded is 
interference between the direct and retransmitted signals at the 
receiver under test.


David N1HAC

On 4/12/12 10:17 AM, MailLists wrote:
GPS being extremely time-dependent, any delay introduced will affect 
positioning precision. Also, the signal is too weak for such an 
amplification/echo cancelling signal chain.
Passive relaying, or using at most a simple amplifier with low enough 
gain, and short signal delay, remain the only feasible concepts.


On 4/12/2012 4:48 PM, Azelio Boriani wrote:
Passive UHF TV repeaters were in use in Italy too. Nowadays, for the 
DVB-T

TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo 
suppression

technique. We have developed our echo suppression signal processor on a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS 
CDMA.


On Thu, Apr 12, 2012 at 3:29 PM, Alan 
Meliawrote:


If the isolation is good and the "clear view" signal is reasonably 
strong,
the passive system works well in hangers, metalclad warehouses, 
ferry lorry

decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message -
From: "Michael Baker"
To:
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??



Time-nutters--

So--  How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below.  The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley.  I was
told that it worked pretty well.

Mike Baker
--

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Re: [time-nuts] Thoughts on lightning protection measures....

[Attila Kinali]

On Thu, 12 Apr 2012 17:39:57 +0300
MailLists  wrote:

> Regarding the TBs, even if they are the only ones directly connected to 
> the antenna, the cable is already punching through the house Faraday 
> cage, and chances are quite high that the lightning discharge won't stop 
> at them.

A house isnt a faraday cage. Not by far. Unless you live in a box made out
of solid 5mm steal plates.

If a lightning hits your house directly and is going down the lightning
rod down into earth there is a good chance that the electric and magnetic
fields you have in the house will fry sensitive electronic equipment


Attila Kinali
-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Temex LPFRS-01

[MailLists]

Well, the saga continues...
A replacement part (for which a thorough check was specifically asked) 
has arrived. It boasts a "Checked OK" written with a marker pen on the 
label. Promising...
With high expectations, the necessary connections were made, power 
applied, and after warming up it locks at precisely 9.999,817,1 MHz... 
bummer.
Sometimes, for (yet) unknown reasons, it unlocks again, and, if the 
frequency adjustment trend is upwards, it locks again at ~10.000.000 
MHz. The lock signal is active even at higher temperatures - that's 
quite better than the first unit, but after a power cycle the story 
repeats... mostly the wrong frequency comes out, but, on the brighter 
side, it's locked.



On 3/18/2012 10:26 AM, MailLists wrote:

Yes...
Thank you, and the others, for the suggestions for cleaning/reviving the
unit, but I can't recommend to my friend to keep a pile of rust (if
water damage really is the problem) advertised as an used working item.

Regards,
bbg


On 3/17/2012 4:10 PM, Azelio Boriani wrote:

LPFRS from fluke.l? OK, then open it up and clean it, the LPFRS from
fluke.l suffers from high humidity/water immersion and usually are very
rusty inside. I have received one that was very bad but after cleaning
with
tetrachloroethylene (translated with google) it is working properly,
maybe
it will fail soon but now works. I complained with fluke.l and he
refunded
me without asking to ship back the LPFRS.
TIP: handle with extreme care an opened LPFRS, there is a flexible PCB
that
holds the DB9 connector that can tear in the corners.

On Sat, Mar 17, 2012 at 10:59 AM, MailLists wrote:


Hello all,

a friend purchased from the bay a in the LPRO configuration.
After
some problems encountered during the first power ups, he asked for
help -
I'm passing the questions further...
After about 9 minutes of warm-up from room temperature (22°C) the lock
signal goes low, but after a short time starts to switch low/high with
decreasing low periods, until it remains high with short low pulses,
spaced
at about 2 seconds. After power-down, and sufficient cooling time, the
cycle repeats.
First step was to reapply the thermal interface to the integrated Al
radiator, which helped a bit, the time during which the unit is locked
growing slightly.
Next step was forced cooling, which helped more, so the lock loss
could be
attributed with high probability to elevated operating temperatures. The
temperature of the base plate (integrated Al radiator) at which lock
gets
lost is about 40°C, so for a reasonable operation it should not pass
about
36°C, at which the power consumption raises to about 17W. That also
means
that for a 1°C/W heat sinking - obtainable with a larger passive HS or
active cooling - operation above 30°C ambient gets practically
impossible
(except refrigeration, Peltier, etc.).

Any further help or suggestions are welcome.

Regards,
bbg

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Re: [time-nuts] Thoughts on lightning protection measures....

[MailLists]

A very efficient solution would be to get the signal/power conducting 
cables out of the lightning path - that means a GPS receiver near the 
antenna, with a local power supply (photo cell panels / buffer 
accumulator) and signal transmission over optical fiber. Quite feasible, 
as a GPS Rx has low power requirements.
If the delay from receiver to the disciplined oscillator is critical, or 
too high, a compensation scheme comes to mind - 2 identical optical 
paths in a loop, with the sent pps signal phase adjusted so that the 
received GPS pps is centered between the sent and the looped one.


Regarding the TBs, even if they are the only ones directly connected to 
the antenna, the cable is already punching through the house Faraday 
cage, and chances are quite high that the lightning discharge won't stop 
at them.



On 4/12/2012 5:03 PM, Azelio Boriani wrote:

I have 2 TBolts but now I'm thinking to buy others to save them from the
sacrifice...

On Thu, Apr 12, 2012 at 3:58 PM, Jim Lux  wrote:


On 4/12/12 6:22 AM, Michael Baker wrote:


Time-nutters--

Around here (N. Central Flori-DUH) it is not uncommon for
near-by lightning strikes to damage underground cables and
wiring. This is why buried wiring to things like driveway
gate-openers are often placed in conduit rather than done
with direct-burial wiring so that if lightning damages the
wiring a new cable can be pulled through the conduit without
having to re-dig the burial trench.

Some years ago I had occasion to hold some long discussions
with Martin Uman, one of the worlds most distinguished and
eminent lightning researchers. He commented that even with
the most extraordinary and costly efforts to install protection
measures, that-- sooner or later-- there was a good chance that
lightning would find a way to damage things.




Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and
effects than any other humans alive.   He's making an excellent point: at
some point, the cost to replace the gear (or the cost of being "off the
air") is smaller than the cost of the protection scheme.

Sometimes, you're better off having a sacrificial element, and a spare in
the closet for speedy repair.


  His lightning research laboratory was located here in

N.Central Florida because it is in the heart of the most
dense strike area in N. America.





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Re: [time-nuts] Thoughts on lightning protection measures....

[MailLists]

Only if it's not part of the sacrificial ritual...

On the more serious part, while the lightning processes, and effects are 
scientifically researched for ages, an efficient lighting protection 
still borders black magic.



On 4/12/2012 5:01 PM, ewkeh...@aol.com wrote:

True if you do not include the cost of the burned down house which is a
possibility.
Bert Kehren


In a message dated 4/12/2012 9:59:08 A.M. Eastern Daylight Time,
jim...@earthlink.net writes:

On  4/12/12 6:22 AM, Michael Baker wrote:

Time-nutters--

  Around here (N. Central Flori-DUH) it is not uncommon for
near-by  lightning strikes to damage underground cables and
wiring. This is why  buried wiring to things like driveway
gate-openers are often placed in  conduit rather than done
with direct-burial wiring so that if  lightning damages the
wiring a new cable can be pulled through the  conduit without
having to re-dig the burial trench.

  Some years ago I had occasion to hold some long discussions
with  Martin Uman, one of the worlds most distinguished and
eminent  lightning researchers. He commented that even with
the most  extraordinary and costly efforts to install protection
measures,  that-- sooner or later-- there was a good chance that
lightning would  find a way to damage things.




Dr. Uman (and his colleague  Dr. Rakov) probably know about lightning and
effects than any other humans  alive.   He's making an excellent point:
at some point, the cost  to replace the gear (or the cost of being "off
the air") is smaller than  the cost of the protection scheme.

Sometimes, you're better off having  a sacrificial element, and a spare
in the closet for speedy  repair.



His lightning research laboratory was located here  in
N.Central Florida because it is in the heart of the most
  dense strike area in N.  America.




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Re: [time-nuts] Thoughts on lightning protection measures....

[Bob Camp]

Hi

Is your house hit multiple times per year now? If so, I'd suggest that's the
issue that needs to be solved. If not, then mount the antenna lower than the
peak of the house and move on.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Azelio Boriani
Sent: Thursday, April 12, 2012 10:04 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thoughts on lightning protection measures

I have 2 TBolts but now I'm thinking to buy others to save them from the
sacrifice...

On Thu, Apr 12, 2012 at 3:58 PM, Jim Lux  wrote:

> On 4/12/12 6:22 AM, Michael Baker wrote:
>
>> Time-nutters--
>>
>> Around here (N. Central Flori-DUH) it is not uncommon for
>> near-by lightning strikes to damage underground cables and
>> wiring. This is why buried wiring to things like driveway
>> gate-openers are often placed in conduit rather than done
>> with direct-burial wiring so that if lightning damages the
>> wiring a new cable can be pulled through the conduit without
>> having to re-dig the burial trench.
>>
>> Some years ago I had occasion to hold some long discussions
>> with Martin Uman, one of the worlds most distinguished and
>> eminent lightning researchers. He commented that even with
>> the most extraordinary and costly efforts to install protection
>> measures, that-- sooner or later-- there was a good chance that
>> lightning would find a way to damage things.
>>
>>
>
> Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and
> effects than any other humans alive.   He's making an excellent point: at
> some point, the cost to replace the gear (or the cost of being "off the
> air") is smaller than the cost of the protection scheme.
>
> Sometimes, you're better off having a sacrificial element, and a spare in
> the closet for speedy repair.
>
>
>  His lightning research laboratory was located here in
>> N.Central Florida because it is in the heart of the most
>> dense strike area in N. America.
>>
>
>
>
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Re: [time-nuts] Re-radiating a GPS signal...??

[MailLists]

GPS being extremely time-dependent, any delay introduced will affect 
positioning precision. Also, the signal is too weak for such an 
amplification/echo cancelling signal chain.
Passive relaying, or using at most a simple amplifier with low enough 
gain, and short signal delay, remain the only feasible concepts.


On 4/12/2012 4:48 PM, Azelio Boriani wrote:

Passive UHF TV repeaters were in use in Italy too. Nowadays, for the DVB-T
TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo suppression
technique. We have developed our echo suppression signal processor on a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS CDMA.

On Thu, Apr 12, 2012 at 3:29 PM, Alan Meliawrote:


If the isolation is good and the "clear view" signal is reasonably strong,
the passive system works well in hangers, metalclad warehouses, ferry lorry
decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message -
From: "Michael Baker"
To:
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??



Time-nutters--

So--  How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below.  The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley.  I was
told that it worked pretty well.

Mike Baker
--

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Re: [time-nuts] Thoughts on lightning protection measures....

[Azelio Boriani]

I have 2 TBolts but now I'm thinking to buy others to save them from the
sacrifice...

On Thu, Apr 12, 2012 at 3:58 PM, Jim Lux  wrote:

> On 4/12/12 6:22 AM, Michael Baker wrote:
>
>> Time-nutters--
>>
>> Around here (N. Central Flori-DUH) it is not uncommon for
>> near-by lightning strikes to damage underground cables and
>> wiring. This is why buried wiring to things like driveway
>> gate-openers are often placed in conduit rather than done
>> with direct-burial wiring so that if lightning damages the
>> wiring a new cable can be pulled through the conduit without
>> having to re-dig the burial trench.
>>
>> Some years ago I had occasion to hold some long discussions
>> with Martin Uman, one of the worlds most distinguished and
>> eminent lightning researchers. He commented that even with
>> the most extraordinary and costly efforts to install protection
>> measures, that-- sooner or later-- there was a good chance that
>> lightning would find a way to damage things.
>>
>>
>
> Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and
> effects than any other humans alive.   He's making an excellent point: at
> some point, the cost to replace the gear (or the cost of being "off the
> air") is smaller than the cost of the protection scheme.
>
> Sometimes, you're better off having a sacrificial element, and a spare in
> the closet for speedy repair.
>
>
>  His lightning research laboratory was located here in
>> N.Central Florida because it is in the heart of the most
>> dense strike area in N. America.
>>
>
>
>
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Re: [time-nuts] Thoughts on lightning protection measures....

[EWKehren]

True if you do not include the cost of the burned down house which is a  
possibility.
Bert Kehren
 
 
In a message dated 4/12/2012 9:59:08 A.M. Eastern Daylight Time,  
jim...@earthlink.net writes:

On  4/12/12 6:22 AM, Michael Baker wrote:
> Time-nutters--
>
>  Around here (N. Central Flori-DUH) it is not uncommon for
> near-by  lightning strikes to damage underground cables and
> wiring. This is why  buried wiring to things like driveway
> gate-openers are often placed in  conduit rather than done
> with direct-burial wiring so that if  lightning damages the
> wiring a new cable can be pulled through the  conduit without
> having to re-dig the burial trench.
>
>  Some years ago I had occasion to hold some long discussions
> with  Martin Uman, one of the worlds most distinguished and
> eminent  lightning researchers. He commented that even with
> the most  extraordinary and costly efforts to install protection
> measures,  that-- sooner or later-- there was a good chance that
> lightning would  find a way to damage things.
>


Dr. Uman (and his colleague  Dr. Rakov) probably know about lightning and 
effects than any other humans  alive.   He's making an excellent point: 
at some point, the cost  to replace the gear (or the cost of being "off 
the air") is smaller than  the cost of the protection scheme.

Sometimes, you're better off having  a sacrificial element, and a spare 
in the closet for speedy  repair.


> His lightning research laboratory was located here  in
> N.Central Florida because it is in the heart of the most
>  dense strike area in N.  America.



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Re: [time-nuts] Thoughts on lightning protection measures....

[Jim Lux]

On 4/12/12 6:22 AM, Michael Baker wrote:

Time-nutters--

Around here (N. Central Flori-DUH) it is not uncommon for
near-by lightning strikes to damage underground cables and
wiring. This is why buried wiring to things like driveway
gate-openers are often placed in conduit rather than done
with direct-burial wiring so that if lightning damages the
wiring a new cable can be pulled through the conduit without
having to re-dig the burial trench.

Some years ago I had occasion to hold some long discussions
with Martin Uman, one of the worlds most distinguished and
eminent lightning researchers. He commented that even with
the most extraordinary and costly efforts to install protection
measures, that-- sooner or later-- there was a good chance that
lightning would find a way to damage things.




Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and 
effects than any other humans alive.   He's making an excellent point: 
at some point, the cost to replace the gear (or the cost of being "off 
the air") is smaller than the cost of the protection scheme.


Sometimes, you're better off having a sacrificial element, and a spare 
in the closet for speedy repair.




His lightning research laboratory was located here in
N.Central Florida because it is in the heart of the most
dense strike area in N. America.




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Re: [time-nuts] Best location for a GPS antenna...?

[Jim Lux]

On 4/12/12 2:09 AM, Rob Kimberley wrote:

There are commercial "re-radiators" for GPS.  I found these on Google:





One of my old suppliers in the UK was marketing a range of these, but I seem
to remember some problem in getting approval in the UK, and they had to drop
them. Things may have changed as this was a few years ago.

Interestingly I've just been looking into this...  Why would you need 
anything special to reradiate.. It's not like you need a particular 
antenna pattern or constant gain or something. What about something like 
a fat monopole against a ground plane, with a attenuator at the feed to 
provide a good terminating impedance for the LNA/Line driver.


If it's L1 only, you don't even need particularly wide bandwidth (<1%)


Yes, I've seen setups at JPL where they reradiate with D&M or Ashtech 
chokering antennas (or even helibowls), but that might be because we've 
got a bunch of them sitting around, so why not use it.



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Re: [time-nuts] Re-radiating a GPS signal...??

[Azelio Boriani]

Passive UHF TV repeaters were in use in Italy too. Nowadays, for the DVB-T
TV, active gap-fillers are used instead. Active gap-fillers are
same-channel repeaters with the necessary, sophisticated echo suppression
technique. We have developed our echo suppression signal processor on a
Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS CDMA.

On Thu, Apr 12, 2012 at 3:29 PM, Alan Melia wrote:

> If the isolation is good and the "clear view" signal is reasonably strong,
> the passive system works well in hangers, metalclad warehouses, ferry lorry
> decks.
> The passive system in the UK used to be refered to as the "Matlock
> Repeater".
>
> Alan
> G3NYK
>
> - Original Message -
> From: "Michael Baker" 
> To: 
> Sent: Thursday, April 12, 2012 2:05 PM
> Subject: [time-nuts] Re-radiating a GPS signal...??
>
>
> > Time-nutters--
> >
> > So--  How do GPS signal re-radiators work?
> >
> > How do you place a GPS antenna on top of a building,
> > pick up the signal with an LNA, amplify it to re-transmit
> > on an inside antenna without the amplified re-transmitted
> > signal getting back into the roof-top receiving antenna?
> >
> > I can see circumstances where a huge metal building
> > (aircraft hangar?) might provide enough isolation to
> > prevent problems, but in many cases I wonder about it...
> > 
> >
> > As an aside note-- I recall seeing, many years ago, a totally
> > passive TV signal repeater on top of a tall hill in mountainous
> > territory relaying a TV station signal to some homes in a valley
> > just below.  The passive repeater consisted of an array of
> > high-gain UHF yagis pointing to the 40 mile distant TV station tower.
> > The yagi array was coupled to another set of high-gain yagi
> > antennas pointing down to the homesites in the valley.  I was
> > told that it worked pretty well.
> >
> > Mike Baker
> > --
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
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Re: [time-nuts] Re-radiating a GPS signal...??

[Alan Melia]

If the isolation is good and the "clear view" signal is reasonably strong,
the passive system works well in hangers, metalclad warehouses, ferry lorry
decks.
The passive system in the UK used to be refered to as the "Matlock
Repeater".

Alan
G3NYK

- Original Message - 
From: "Michael Baker" 
To: 
Sent: Thursday, April 12, 2012 2:05 PM
Subject: [time-nuts] Re-radiating a GPS signal...??


> Time-nutters--
>
> So--  How do GPS signal re-radiators work?
>
> How do you place a GPS antenna on top of a building,
> pick up the signal with an LNA, amplify it to re-transmit
> on an inside antenna without the amplified re-transmitted
> signal getting back into the roof-top receiving antenna?
>
> I can see circumstances where a huge metal building
> (aircraft hangar?) might provide enough isolation to
> prevent problems, but in many cases I wonder about it...
> 
>
> As an aside note-- I recall seeing, many years ago, a totally
> passive TV signal repeater on top of a tall hill in mountainous
> territory relaying a TV station signal to some homes in a valley
> just below.  The passive repeater consisted of an array of
> high-gain UHF yagis pointing to the 40 mile distant TV station tower.
> The yagi array was coupled to another set of high-gain yagi
> antennas pointing down to the homesites in the valley.  I was
> told that it worked pretty well.
>
> Mike Baker
> --
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
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[time-nuts] Thoughts on lightning protection measures....

[Michael Baker]

Time-nutters--

Around here (N. Central Flori-DUH) it is not uncommon for
near-by lightning strikes to damage underground cables and
wiring.   This is why buried wiring to things like driveway
gate-openers are often placed in conduit rather than done
with direct-burial wiring so that if lightning damages the
wiring a new cable can be pulled through the conduit without
having to re-dig the burial trench.

Some years ago I had occasion to hold some long discussions
with Martin Uman, one of the worlds most distinguished and
eminent lightning researchers.  He commented that even with
the most extraordinary and costly efforts to install protection
measures, that-- sooner or later-- there was a good chance that
lightning would find a way to damage things.

His lightning research laboratory was located here in
N.Central Florida because it is in the heart of the most
dense strike area in N. America.

Mike Baker


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Re: [time-nuts] Re-radiating a GPS signal...??

[Bob Camp]

Hi

The re-radiators are active devices. They are every bit as much a lightning
attractor as the GPS it's self. They also cost more than a TBolt (even at
current prices).

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Michael Baker
Sent: Thursday, April 12, 2012 9:06 AM
To: time-nuts@febo.com
Subject: [time-nuts] Re-radiating a GPS signal...??

Time-nutters--

So--  How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below.  The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley.  I was
told that it worked pretty well.

Mike Baker
--

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[time-nuts] Re-radiating a GPS signal...??

[Michael Baker]

Time-nutters--

So--  How do GPS signal re-radiators work?

How do you place a GPS antenna on top of a building,
pick up the signal with an LNA, amplify it to re-transmit
on an inside antenna without the amplified re-transmitted
signal getting back into the roof-top receiving antenna?

I can see circumstances where a huge metal building
(aircraft hangar?) might provide enough isolation to
prevent problems, but in many cases I wonder about it...


As an aside note-- I recall seeing, many years ago, a totally
passive TV signal repeater on top of a tall hill in mountainous
territory relaying a TV station signal to some homes in a valley
just below.  The passive repeater consisted of an array of
high-gain UHF yagis pointing to the 40 mile distant TV station tower.
The yagi array was coupled to another set of high-gain yagi
antennas pointing down to the homesites in the valley.  I was
told that it worked pretty well.

Mike Baker
--

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Re: [time-nuts] Best location for a GPS antenna...?

[Ulrich Bangert]

Stefan,

my mushroom type of gps antenna is mounted on a metallic cantilever arm abt.
0.6 m aside a pole that extends 1 m above the height of the gps antenna.
Then a 2 m long vertical amateur radio antenna is mounted on top of the
pole. The pole is exactly in the east of the gps antenna. I attach a
visibility plot. Everything else with exception of exactly east is the
effect of trees around the house being higher than antenna height. While
this arrangement is not what you suggest in terms of lightning protection it
shows that the pole itself has not a big impact on gps reception.

Best regards
Ulrich Bangert 

> -Ursprungliche Nachricht-
> Von: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] Im Auftrag von Heinzmann, 
> Stefan (ALC NetworX GmbH)
> Gesendet: Donnerstag, 12. April 2012 10:10
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Best location for a GPS antenna...?
> 
> 
> What about mounting the antenna on the side of the metal 
> pole, with the top of the pole extending a foot or more above 
> the antenna?
> 
> The idea is to have the lightning bolt strike the pole, but 
> not the antenna. The cable shield would need to be insulated 
> from the pole, but grounded on entry to the building.
> 
> Would the pole disturb the GPS signal to any noticeable extent?
> 
> Cheers
> Stefan
> 
> 
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PChart.pdf
Description: Adobe PDF document
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Re: [time-nuts] WWVB phase modulation test April 15-16

[Azelio Boriani]

I have a couple of BNC-to-scope_probe adapters...

On Thu, Apr 12, 2012 at 9:56 AM, Hal Murray  wrote:

>
> > Just the T and a DC block. 1/4 wave at 60 kHz is far, far longer than any
> > cable you have.
>
> This is time-nuts.  Somebody is likely to do something most of us would
> consider, well, nutty.
>
> It's probably reasonable to make a lumped-circuit approximation of a long
> transmission line at 60 KHz or 100 KHz.
>
> Many years ago, when we were working on early 10 Mb Ethernet, a friend
> rigged
> up a good approximation to a long chunk of coax with 1 R and 1 C and a few
> clip leads.  It looked pretty good on a scope.
>
> I ordered several 500 ft spools of coax so we could test the real thing.
>  500
> ft of Ethernet coax (not thinwire) is a serious spool.  A key step was
> getting the maintainance guy to build a dolly with serious casters.  He was
> happy to do something strange.  The result was slight overkill which is
> what
> I wanted.  It worked great.  Every lab should have one.  :)
>
> How many of you have used the Tek scope-probe to BNC adapter?  I tried a
> bit
> but couldn't find anything on the web.  The idea was (roughly) that you
> put a
> BNC Tee in the line you wanted to watch and this magic gizmo on the Tee.
>  One
> end was BNC.  The other end was a hole where you inserted a scope probe.
>  The
> idea was to avoid the inductance on the pigtail for the ground cliplead.
>
> --
>
> Not quite so many years ago, we built a SONET/OC-3 delay box.  It was just
> a
> fiber optic receiver, FPGA, knobs, memory, and fiber optic transmitter.
>  The
> FPGA could just barely  run at 155 megabits.  We used a recycled memory
> module.  I think it was 36 bits wide with 1 megabit chips.  The idea was to
> let the software guys test long links in their lab.  It worked great.  (I
> think that size memory covered (roughly) California to Paris.)
>
>
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
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Re: [time-nuts] Best location for a GPS antenna...?

[Rob Kimberley]

This is a good idea, and I know has been used in the past. I believe that
Datum & Austron used to recommend something like this for areas where
lightning was a problem.

Rob Kimberley

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Heinzmann, Stefan (ALC NetworX GmbH)
Sent: 12 April 2012 09:10
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?

What about mounting the antenna on the side of the metal pole, with the top
of the pole extending a foot or more above the antenna?

The idea is to have the lightning bolt strike the pole, but not the antenna.
The cable shield would need to be insulated from the pole, but grounded on
entry to the building.

Would the pole disturb the GPS signal to any noticeable extent?

Cheers
Stefan


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Re: [time-nuts] Best location for a GPS antenna...?

[Rob Kimberley]

There are commercial "re-radiators" for GPS.  I found these on Google:





One of my old suppliers in the UK was marketing a range of these, but I seem
to remember some problem in getting approval in the UK, and they had to drop
them. Things may have changed as this was a few years ago.

Rob Kimberley


-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Andrea Baldoni
Sent: 11 April 2012 21:06
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?

On Wed, Apr 11, 2012 at 10:19:40AM -0400, Bob Bownes wrote:

> I do like the optical isolation suggestion. While less than optimal, 
> perhaps the easiest solution is not to put the isolation between the 
> t'bolt and the antenna, but to put the isolation between the t'bolt 
> and the distribution amplifier.

By the way, would it be possible to retransmit the GPS signal to isolate it?

I mean, rx external antenna -> preamp -> tx directional internal antenna ->
big air gap -> rx directional internal antenna -> receiver.
The preamp would not be so power hungry as the full thunderbolt and maybe it
could be powered via a magnetic link (or a little solar panel with a lamp
illuminating it).

Best regards,
Andrea Baldoni

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Re: [time-nuts] Best location for a GPS antenna...?

[David C. Partridge]

A lightening strike anywhere within 10ft will probably total your antenna, the 
coax and the GPS receiver attached to it. 

D.
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf 
Of Heinzmann, Stefan (ALC NetworX GmbH)
Sent: 12 April 2012 09:10
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Best location for a GPS antenna...?

What about mounting the antenna on the side of the metal pole, with the top of 
the pole extending a foot or more above the antenna?

The idea is to have the lightning bolt strike the pole, but not the antenna. 
The cable shield would need to be insulated from the pole, but grounded on 
entry to the building.

Would the pole disturb the GPS signal to any noticeable extent?

Cheers
Stefan


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Re: [time-nuts] Best location for a GPS antenna...?

[Heinzmann, Stefan (ALC NetworX GmbH)]

What about mounting the antenna on the side of the metal pole, with the top of 
the pole extending a foot or more above the antenna?

The idea is to have the lightning bolt strike the pole, but not the antenna. 
The cable shield would need to be insulated from the pole, but grounded on 
entry to the building.

Would the pole disturb the GPS signal to any noticeable extent?

Cheers
Stefan


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Re: [time-nuts] WWVB phase modulation test April 15-16

[Hal Murray]

> Just the T and a DC block. 1/4 wave at 60 kHz is far, far longer than any
> cable you have. 

This is time-nuts.  Somebody is likely to do something most of us would 
consider, well, nutty.

It's probably reasonable to make a lumped-circuit approximation of a long 
transmission line at 60 KHz or 100 KHz.

Many years ago, when we were working on early 10 Mb Ethernet, a friend rigged 
up a good approximation to a long chunk of coax with 1 R and 1 C and a few 
clip leads.  It looked pretty good on a scope.

I ordered several 500 ft spools of coax so we could test the real thing.  500 
ft of Ethernet coax (not thinwire) is a serious spool.  A key step was 
getting the maintainance guy to build a dolly with serious casters.  He was 
happy to do something strange.  The result was slight overkill which is what 
I wanted.  It worked great.  Every lab should have one.  :)

How many of you have used the Tek scope-probe to BNC adapter?  I tried a bit 
but couldn't find anything on the web.  The idea was (roughly) that you put a 
BNC Tee in the line you wanted to watch and this magic gizmo on the Tee.  One 
end was BNC.  The other end was a hole where you inserted a scope probe.  The 
idea was to avoid the inductance on the pigtail for the ground cliplead.

--

Not quite so many years ago, we built a SONET/OC-3 delay box.  It was just a 
fiber optic receiver, FPGA, knobs, memory, and fiber optic transmitter.  The 
FPGA could just barely  run at 155 megabits.  We used a recycled memory 
module.  I think it was 36 bits wide with 1 megabit chips.  The idea was to 
let the software guys test long links in their lab.  It worked great.  (I 
think that size memory covered (roughly) California to Paris.)


-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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