This is the best non-geek story that I have seen.
http://tinyurl.com/lvy2z2t
http://www.pbs.org/newshour/bb/science/july-dec13/gps_08-02.html
(Audio is 7 minutes.)
New research shows the GPS software we all rely on can be hacked and
manipulated. In June, a team at the University of Texas employe
Hi
The math is pretty simple:
The Q of quartz goes up as the frequency goes down.
A crystal resonator's performance (Q) is limited by it's thickness to diameter
ratio.
At some point the resonator design impacts the Q of the resonator more than the
Q of the raw quartz.
Holders are available
Even HP used 5MHz when it counted (no pun intended!) - the 5245L used a 1MHz
timebase while the higher spec timebase in the 5245M used 5MHz.
DaveB, NZ
- Original Message -
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: Saturday, August 03, 2013 8:
Interesting, I have heard for years from the senior Time and Freq researchers I
work with that 5MHz was a sweet spot. I will ask if there is a reason and
proven physics behind it but these are individuals that are well grounded in
science. They almost always multiply 5MHz if they needed 10MHz
In looking around the local Radio Shack a few days ago, I notices a silver
dollar sized GPS module w/ patch antenna for use in home brew robots. The
thing is supposedly good to 5 Meters and costs about $55. It appears to
have a serial ASCII interface.
There is nothing obvious on the RS website. Do
Bob:
Well, this is discouraging. The receiver seems to work -- receives the
sats it should. Seriously doubt there's any multipath out here in the
boondocks. Maybe some tree absorption at very low elevation, but very
little in the way of reflectors. I'm on 10 acres on a hillside, with
trees
Hi
Except for HP, everything from the US would have been 5 MHz as well.
Bob
On Aug 2, 2013, at 3:51 PM, Robert Atkinson wrote:
> Hi
> Most of the British Racal standards are 5MHz. It may well have been down to
> what was the best performance of the nationally avilable crystals. Everthing
> i
Hi
Even today you will get better ADEV off of a large package (HC-40) 5 MHz
crystal than off of a 10 MHz device. Of course very few people make such an
oscillator any more. Buyers are after other things.
Bob
On Aug 2, 2013, at 3:51 PM, Robert Atkinson wrote:
> Hi
> Most of the British Racal
Hi
You might want to check the equipment you are going to use with it. A lot of
early gear that is marked "10 MHz" really has a range of frequencies it will
accept. They often will accept anything that is a sub-multiple of 10 MHz (5,
2.5, 3.3, 1.25 etc). They used a simple phase detector to
Hi
Most of the British Racal standards are 5MHz. It may well have been down to
what was the best performance of the nationally avilable crystals. Everthing is
a compromise.
It is easy to double a 5MHz output to 10MHz. One way is to pass it through a
bridge rectifier (high speed diodes of course)
You can double it very easily. Feed it into a full wave bridge and you will
get 10 MHz.
Amplify and filter as desired.
Regards,
Tom
- Original Message -
From: "Euclides Chuma"
To:
Sent: Friday, August 02, 2013 2:40 PM
Subject: Re: [time-nuts] 5MHz x 10MHz
Hi,
I thank all for your
Hi
It may well have been teamed up with a piece of Russian designed equipment.
Bob
On Aug 2, 2013, at 2:40 PM, Euclides Chuma wrote:
> Hi,
>
> I thank all for your responses.
>
> My question arose because I bought a TFL Rubidium Standard and the signal
> output is 5 MHz. It is a great rubid
Hi,
I thank all for your responses.
My question arose because I bought a TFL Rubidium Standard and the
signal output is 5 MHz. It is a great rubidium standard so I dont
understand the reason of the 5 MHZ signal output since the 10 MHz is the
common standard.
Best regards
___
Hi
Quartz it's self has no "sweet spot". The only issue is how low you can go in a
specific sized crystal holder before you start to run into trouble. A TO-5
crystal will have a different minimum frequency than an HC-40.
Bob
On Aug 2, 2013, at 2:30 PM, Mike Feher wrote:
> It was my understan
It was my understanding that this "sweet spot" was optimum a little above 3
MHz, so, 3rd overtone crystals are used to generate a stable, low phase
noise 10 MHz. Prior to that, 5 MHz was used and before that 1 MHz Regards
- Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-
Hi
If you go back far enough, you will find 1 MHz and 100 KHz used as reference
standards. They certainly were common place in gear through the 1960's.
Pre-WWII, open 100 Kc quartz bars were often the "standard" of choice.
Anything much higher than that was increasingly less stable.
Post WWII
Many important lab references over past 50, 60 years are named and
characterized at http://www.ieee-uffc.org/main/history-norton.asp
2.5MHz and 5 MHz seem common as far back as the 1950's and 1960's (and I've
used some of them! e.g. Sulzer) and continue through today.
Late 60's and early 70's HP
It is my understanding that Quartz has a sweet spot at 5MHz that makes it ideal
if the lowest possible phase noise and highest stability are needed.
Thomas Knox
> Date: Fri, 2 Aug 2013 19:57:16 +0200
> From: mag...@rubidium.dyndns.org
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] 5MHz x 1
Hi Euclides,
On 02/08/13 18:31, Euclides Chuma wrote:
Hi,
Why any equipments use 5 MHz and others use 10 MHz reference standard?
There are some benefits (traditionally) in using 5 MHz over 10 MHz, but
10 MHz have become a common standard. The actual frequency isn't really
magic, but 5 MHz a
Hi,
Why any equipments use 5 MHz and others use 10 MHz reference standard?
Thanks
Euclides Chuma
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Hi
On Aug 2, 2013, at 11:27 AM, Magnus Danielson
wrote:
> On 31/07/13 23:59, Alberto di Bene wrote:
>> A really fascinating story in pictures of the preparation and
>> manufacture of quartz crystals for radio communication.
>> Dating back to 1943... how times have changed...
>>
>> Copied from
Hi
The story of the crystal etching process is true, and Dr. Bottom did play a
part in it. He also spent a *lot* of the next decades publicizing all of that.
Others who were there at the time had slightly different stories to tell, at
least in private.
Bob
On Aug 2, 2013, at 1:10 PM, Pete Lan
A paper on the effort in WWII and some of the problems
... millions f the unetched units were destroyed...
http://www.ieee-uffc.org/main/history-bottom.asp
On Wed, Jul 31, 2013 at 5:59 PM, Alberto di Bene wrote:
> A really fascinating story in pictures of the preparation and manufacture
>
On 31/07/13 23:59, Alberto di Bene wrote:
A really fascinating story in pictures of the preparation and
manufacture of quartz crystals for radio communication.
Dating back to 1943... how times have changed...
Copied from another list.
http://archive.org/details/6101_Crystals_Go_to_War_01_20_16_
Hi
One would assume that the rest of the world also made a few crystals during the
same period.
Bob
On Aug 1, 2013, at 10:41 PM, "Charles P. Steinmetz"
wrote:
> pete wrote:
>
>> I can't find it but I saw a reference to how may units were made during
>> WWII, does anyone have the number and
Hi
Either a blown receiver (likely the SAW filter) or antenna multi path.
Bob
On Aug 1, 2013, at 8:45 PM, Jim Sanford wrote:
> I am seeing the same thing -- big jumps every single time a satellite is
> counted or not. Elevation mask 10 degrees, which should be very good and
> stable for my
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