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Today's Topics:
1. Re: Why are 1PPS signals so skinny? (Jim Hickstein)
2. Re: Why are 1PPS signals so skinny? (Azelio Boriani)
3. Re: wwvb weak on east coast especially when the pre-amps
under wa... (Michael Blazer)
4. Re: wwvb weak on east coast especially when the pre-amps
under wa... (Azelio Boriani)
5. Re: Why are 1PPS signals so skinny? (Michael Blazer)
6. Re: Why are 1PPS signals so skinny? (Bob Camp)
7. Re: wwvb weak on east coast especially when thepre-amps under
wa... (Alan Melia)
----------------------------------------------------------------------
Message: 1
Date: Mon, 14 May 2012 18:18:20 -0500
From: Jim Hickstein<[email protected]>
To: [email protected]
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 2012/05/14 18:02, [email protected] wrote:
https://assist.daps.dla.mil/quicksearch/ is the search site for
military standards.
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob
Sedgwick -- who was to hydraulics what I am to computers, only he has a
number
of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it
went without comment for quite a while until someone tried to look it up.
This
escalated to a bird colonel, who then tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
------------------------------
Message: 2
Date: Tue, 15 May 2012 01:21:26 +0200
From: Azelio Boriani<[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:
<CAL8XPmOc8cLJ3aGBcqJsJB=fbw5xtq-_fy54r9eddudux+a...@mail.gmail.com
Content-Type: text/plain; charset=ISO-8859-1
Maybe the correct number is MIL-STD-188-115?
On Tue, May 15, 2012 at 1:18 AM, Jim Hickstein<[email protected]> wrote:
On 2012/05/14 18:02, [email protected] wrote:
https://assist.daps.dla.mil/quicksearch/ is the search site for
military standards.
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it went without comment for quite a while until someone tried to look
it up. This escalated to a bird colonel, who then tracked down the
miscreant.
It stands for Make It Like The G-D Blueprint For Once.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
------------------------------
Message: 3
Date: Mon, 14 May 2012 18:23:31 -0500
From: Michael Blazer<[email protected]>
To: [email protected]
Subject: Re: [time-nuts] wwvb weak on east coast especially when the
pre-amps under wa...
Message-ID:<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Here's comparison for various type of conformal coating:
http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
https://assist.daps.dla.mil/quicksearch/>
I think there is a type that is 'serviceable' and removable with alcohol.
Mike
On 5/14/2012 6:01 PM, [email protected] wrote:
The other option of course is to pressurise the box with dry air to
ensure
a positive pressure differential, such that the net flow is always
outwards
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
the
enclosure it still doesn't prevent condensation forming on circuit
boards,
and powered circuit boards and condensation don't really go well
together.
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
the
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
to
be fitted in externally mounted vented enclosures, so not a great deal
of
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
plastic spray
that provided a good barrier but was a bit more flexible than the usual
MOD
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
[email protected] writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
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and follow the instructions there.
------------------------------
Message: 4
Date: Tue, 15 May 2012 01:25:54 +0200
From: Azelio Boriani<[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] wwvb weak on east coast especially when the
pre-amps under wa...
Message-ID:
<cal8xpmpcb-dwcpot0nmfp+tdpdrck-xjxxvjwytja+rqmux...@mail.gmail.com
Content-Type: text/plain; charset=ISO-8859-1
We use the Plastik70 from Kontakt chemie
On Tue, May 15, 2012 at 1:23 AM, Michael Blazer<[email protected]>
wrote:
Here's comparison for various type of conformal coating:
http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
https://assist.daps.dla.mil/quicksearch/>
I think there is a type that is 'serviceable' and removable with alcohol.
Mike
On 5/14/2012 6:01 PM, [email protected] wrote:
The other option of course is to pressurise the box with dry air to
ensure
a positive pressure differential, such that the net flow is always
outwards
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
the
enclosure it still doesn't prevent condensation forming on circuit
boards,
and powered circuit boards and condensation don't really go well
together.
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
the
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
to
be fitted in externally mounted vented enclosures, so not a great deal
of
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
plastic spray
that provided a good barrier but was a bit more flexible than the usual
MOD
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
[email protected] writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that
all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is
vapor
tight.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
------------------------------
Message: 5
Date: Mon, 14 May 2012 18:26:58 -0500
From: Michael Blazer<[email protected]>
To: [email protected]
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I haven't heard that one before. I try to slip in the TLAR check in all
the test procedures I write. When 'they' ask, I look at it and say:
"That Looks About Right".
Mike
On 5/14/2012 6:18 PM, Jim Hickstein wrote:
On 2012/05/14 18:02, [email protected] wrote:
https://assist.daps.dla.mil/quicksearch/ is the search site for
military standards.
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
only he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a
drawing, and it went without comment for quite a while until someone
tried to look it up. This escalated to a bird colonel, who then
tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
------------------------------
Message: 6
Date: Mon, 14 May 2012 19:30:49 -0400
From: Bob Camp<[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:<[email protected]>
Content-Type: text/plain; charset=iso-8859-1
Hi
I would bet that the basic electrical definition of the "skinny" PPS dates
at least to the mid 50's if not earlier.
Bob
On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
Mark, Azelio and Bj?rn,
On 05/14/2012 06:33 PM, [email protected] wrote:
Mark& Azelio,
Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
More modern 3-5.5V into 50ohm, 20us.
http://contracting.tacom.army.mil/majorsys/jab/DAGR%20Interface%20Specification.pdf
Above are two standards demanding short skinny 1PPS pulses. Are there
any
other standards with distinct shape requirements on 1PPS pulses?
You need to look at MIL STD 188/155 which if I recall things was
initially formed in the 60thies.
An AccuBeat presentation actually says that the PPS was originally
defined in it.
The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
than we are used to know. It specified 5 MHz as base frequency, or power of
2 multiples (10, 20, 40 MHz... ).
It was later reformulated in the PTTI spec, which ICD GPS 060 is a
derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
I was not able to find MIL STD 188-155 on the net right now, but I have
been able to download it before, so if someone is a more lucky it should
surface. I should have my download somewhere.
Cheers,
Magnus
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------------------------------
Message: 7
Date: Tue, 15 May 2012 00:32:11 +0100
From: "Alan Melia"<[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps under wa...
Message-ID:<012501cd3229$cb66eae0$4001a8c0@lark>
Content-Type: text/plain; charset="iso-8859-1"
Well almost Nigel, if you look at molecule mean velocities they are always
able to diffuse down a concentration gradient (i.e from wet into dry)
despite a small reverse presure gradient. It just takes longer under those
conditions :-))....which is often "enough"
Alan G3NYK
----- Original Message -----
From:<[email protected]>
To:<[email protected]>
Sent: Tuesday, May 15, 2012 12:01 AM
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps
under wa...
The other option of course is to pressurise the box with dry air to
ensure
a positive pressure differential, such that the net flow is always
outwards
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
the
enclosure it still doesn't prevent condensation forming on circuit
boards,
and powered circuit boards and condensation don't really go well
together.
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
the
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
to
be fitted in externally mounted vented enclosures, so not a great deal
of
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
plastic
spray
that provided a good barrier but was a bit more flexible than the usual
MOD
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
[email protected] writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
------------------------------
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End of time-nuts Digest, Vol 94, Issue 89
*****************************************
