[time-nuts] LPRO Pressure Sensitivity

[Bob Camp]

Hi

That was just a test to see if anybody was watching. 

It should read:  

... A change of one in 1,000,000,000,000...

... change of 0.001 Hz ...

I'm sticking to my test story no matter what. Any contrary evidence of
freshly emptied Riesling bottles rolling around the floor should be ignored.


Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bob Camp
Sent: Thursday, January 21, 2010 11:42 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] LPRO Pressure Sensitivity

Hi

>From the ever useful Wikipedia:

http://en.wikipedia.org/wiki/Parts-per_notation

ppt = parts per trillion. A change of one in 1,000,000,000. 

Just like ppm or ppb, only smaller.

In this context at 10 MHz, 10 ppt would be a change of 0.0001 Hz. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of SAL CORNACCHIA
Sent: Thursday, January 21, 2010 10:45 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] LPRO Pressure Sensitivity

Hi Bob, 
Can You explain what 10 PPT stands for.
Thank You
 





________________________________
From: Bob Camp <lists at cq.nu>
To: Discussion of precise time and frequency measurement
<time-nuts at febo..com>
Sent: Thu, January 21, 2010 7:50:43 AM
Subject: Re: [time-nuts] LPRO Pressure Sensitivity

Hi

Yes indeed. 

There really isn't a lot of data out there on pressure on rubidiums. Of
course we don't talk about it a lot on our data sheets either ...

If you accept that a normal day might have a 100 millibar change,  That
changes the frequency 10 ppt, if the guess is right. At 10X that level it
would be as significant as temperature on a good unit. If it was that big it
should get a lot more attention ...

Bob


On Jan 21, 2010, at 4:53 AM, Magnus Danielson wrote:

> Bob Camp wrote:
>> Hi
>> Has anybody taken any data on LPRO's to see what their pressure
sensitivity is? I'm guessing it's  ~ 0.1 ppt / millibar. That's only a guess
backed up by no data at all ....
> 
> Do you mean 1E-13 per millibar? (I am only guessing)
> 
> Cheers,
> Magnus
> 
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