You could cut up a military surplus RF blanket :-) For those who don't
know, you cover the radome of an aircraft with this when the radar is
transmitting, so you don't cook anyone nearby. I never knew how
effective it was, but I didn't walk in front of the aircraft, just to
be safe.
Joe Gray
W5JG
You can get inexpensive conductive foam from Amazon.
On 4/4/2012 5:53 AM, Michael Baker wrote:
Hello, Time-Nutters--
I saw a rather expensive GPS antenna made by one of the
big-name GPS survey equipment mfgrs that was mounted
on top of a 12 or 15 inch diameter disc about 3/4 inch thick.
Turns
So it can be done: try to emulate the Zephyr GPS antenna with the RF
absorber.
On Wed, Apr 4, 2012 at 3:56 PM, Robert Berg bo...@pobox.com wrote:
You can get inexpensive conductive foam from Amazon.
On 4/4/2012 5:53 AM, Michael Baker wrote:
Hello, Time-Nutters--
I saw a rather expensive
On 4/4/12 6:56 AM, Robert Berg wrote:
You can get inexpensive conductive foam from Amazon.
Not all conductive foam works as a decent RF absorber. If the
conductivity isn't well matched to 377 ohms, then the RF reflects right
off of it. The black foam that ICs used to come in is a good
If foliage does such a number on GPS signals, just fill a big garbage bag
with yard debris and set the antenna in the middle of that.
On 04/04/2012 05:53 AM, Michael Baker wrote:
Hello, Time-Nutters--
I saw a rather expensive GPS antenna made by one of the
big-name GPS survey equipment mfgrs
On 4/4/12 7:35 AM, Chuck Forsberg WA7KGX N2469R wrote:
If foliage does such a number on GPS signals, just fill a big garbage bag
with yard debris and set the antenna in the middle of that.
*wet* yard debris..
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A google of helibowl GPS turns up dozens..
But here's a reference that might be useful to the tinkerer:
M
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Oops hit send accidentally..
Charles Counselman, Multipath-Rejecting GPS antennas, IEEE Proceedings,
V87, #1, Jan 1999, pp 86-91
The antenna in the paper is one approach, but of more interest are the
references..
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Hi Mike:
I used military surplus radar absorbing material to stop reflections on a satellite antenna by applying it to the rain
gutter, see:
http://www.prc68.com/I/Images/SB_angw.jpg
A sheet of this stuff about 4 x 6 feet weighed maybe 40 pounds. An easy way to confirm it works is to use it
I asked this on an NTP list, got some guesses, but no knowledgeable
responses.
I've got a Trimble Thunderbolt PPS source for NTP, Linux 2.6.35, on a
quad core CPU. PPS source is coming into a multiport serial card, which
/proc/interrupts shows is sharing IRQ with some inactive USB ports (IRQ
Could the CPU be reducing its clock rate when it's not being loaded? Just
a guess, most multi-core processors these days have power saving features
like that.
--
eric
On Wed, Apr 4, 2012 at 3:22 PM, Mike S mi...@flatsurface.com wrote:
I asked this on an NTP list, got some guesses, but no
I found that the AMD processors change CPU frequency with load and this seemed
to upset any NTP calculations.
In the end I went to Intel CPU (Mutter mutter).
Regards
Randall
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of Mike S
That is the AMD speed step, but doesn't intel do the same thing?
Incidentally, there are hacks for linux to make it more real time, i.e.
lower latency. I never messed with them, but you find this mentioned
related to multimedia oriented distributions.
On 4/4/2012 3:53 PM, Randall Prentice
My first job was in a blasting cap plant in 1960. Raw materials and
finished product were kept in earthen bunkers separated by a distance
that would prevent an explosion in one from propagating (the distances
were found by experience).
Tall, grounded masts were spaced among the bunkers to prevent
The INTEL HRET (High Resolution blagh Timer) seemed to work whereas the AMD
equivalent didn't seem to fix the problem.
Note: this was older AMD ATHLON processors, they may have fixed this by now.
Regards
Randall
-Original Message-
From: time-nuts-boun...@febo.com
On 4/4/2012 6:51 PM, Eric Williams wrote:
Could the CPU be reducing its clock rate when it's not being loaded? Just
a guess, most multi-core processors these days have power saving features
like that.
On Wed, Apr 4, 2012 at 3:22 PM, Mike Smi...@flatsurface.com wrote:
I've played around
El 05/04/2012 00:58, gary escribió:
That is the AMD speed step, but doesn't intel do the same thing?
I suppose so. In any case, under Linux you can force off the speed step
(i.e. force the CPU to a fixed clock). I did that some time ago in a
Dell server with a dual quad-core Opteron with
On 4 Apr, 2012, at 16:10 , Mike S wrote:
On 4/4/2012 6:51 PM, Eric Williams wrote:
Could the CPU be reducing its clock rate when it's not being loaded? Just
a guess, most multi-core processors these days have power saving features
like that.
On Wed, Apr 4, 2012 at 3:22 PM, Mike
Hi all,
While we're on this subject, I have a related question.
I recently bought one of those cone shaped Lucent GPS timing antennas from a
vendor in China. I'm using it for one of my GPS controlled clocks which
contains a 6 channel Oncore VP receiver and is on the end of about 15 feet
of
I mounted the antenna on a small Al plate about 10 X 20 cm attached
to a balcony rail 3 stories from the ground with a clear view of about 75%
of the sky.
I would have expected that the receiver would see quite a few satellites, a
similar arrangement with a magnetic puck antenna regularly sees up
I thought many of you would be interested in this article :
http://www.devmonkey.edn.com/blog/jon-titus-blog/how-do-you-know-correct-time?cid=Newsletter+-+EDN+on+Development+Tools
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On 4/4/2012 10:41 PM, Steve . wrote:
breaking the 1pps down as far as 10micro seconds,The
most obviously problem is that you are trying to use an inaccurate clock
source(the pc)
Your reply ignores the simple fact that it _does_ track within a couple
of microseconds, as long as the processor
It doesn't matter how fast the CPU clock rate is because you are not
dealing with a simple rate monotonicity. There are far too many
inconstancies in a PC to properly apply simple O(n) algorithms.
Your reply ignores the simple fact that it _does_ track within a couple of
microseconds, as long as
I built a small form factor PC using the Intel D525.
http://ark.intel.com/products/49490/Intel-Atom-processor-D525-%281M-Cache-1_80-GHz%29
If you look at the features (or lack thereof!), it lacks turbo boost
and enhanced Intel Speed Step technology. So you may not have to
resort to using a
On Thu, Apr 5, 2012 at 12:17 AM, gary li...@lazygranch.com wrote:
I built a small form factor PC using the Intel D525.
http://ark.intel.com/products/49490/Intel-Atom-processor-D525-%281M-Cache-1_80-GHz%29
If you look at the features (or lack thereof!), it lacks turbo boost and
enhanced
On Wed, Apr 4, 2012 at 9:17 PM, gary li...@lazygranch.com wrote:
I built a small form factor PC using the Intel D525.
http://ark.intel.com/products/49490/Intel-Atom-processor-D525-%281M-Cache-1_80-GHz%29
I did the same thing. They work well and even if you have a free
quad core PC in a
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131663
Yep. This is what I run 24 and 7 for a number of monitoring tasks. It
has an Intel SSD. Mobo was $140 at Fry's. SSD was a Fry's special too.
It has a Nvidia ion2 (it does home theater PC streaming at times.] USB
3. Gigabit
On Wed, Apr 4, 2012 at 9:22 PM, Steve . iteratio...@gmail.com wrote:
If the architecture has cache or wait states, it is still subject to be a
moving target. I'm naturally skeptical on all architectures that have
multiple channels, show me an architecture with cache or waits states and
i'll
As a rule of thumb, any general purpose architecture will be less
effective at a specific task than a specially designed one. That applies
more and more to the modern way of solving tasks: software.
The PC is one of the classical examples of GPA, and as such it is best
to know its limitations,
Indeed, I'm looking forward to getting a few raspberry pis to play with. NTP is
but one of the interesting time related projects possible with a $35(us) Linux
platform. The system has a number of i/o pins directly exposed that will make
interfacing interesting.
On a side note, speaking of
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