[time-nuts] LTE-Lite module

Bob Camp kb8tq at n1k.org
Mon Oct 20 19:10:33 EDT 2014


Hi

Ok, so Bob took a little literary license to make a point :)

_________________

If you spread out past just MV 89’s you can indeed span a range from about 4x10^-13 out to 2 or 3x10^-11 for various parts you see for sale on the auction sites. Yes you will buy a *lot* of OCXO’s and sort through them before you find the one that is at the low end of that range. Even if you stick with one model, some of them seem to have a pretty wide spread ….

Bob

> On Oct 20, 2014, at 7:01 PM, Bert Kehren via time-nuts <time-nuts at febo.com> wrote:
> 
> Allow me to clarify.
> I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3  
> month +  burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. 
> Only two have been tested for ADEV and are close to 1 E-12,  2X not 10  X.
> Bert Kehren
> 
> 
> In a message dated 10/20/2014 5:58:37 P.M. Eastern Daylight Time,  
> kb8tq at n1k.org writes:
> 
> Hi
> 
> The  problem is that there are no “magic coefficients”. What you run 
> depends very  much on the exact OCXO you have, the environment you run it in, and 
> the result  you are after. 
> 
> For instance, Bert is after frequency stability. Tom is  after the right 
> time. Each of them will have very different coefficients for  the same 
> oscillator. 
> 
> My Morion OCXO has a floor of 2x10^-12, Bert has  some that are 10X better 
> than that (maybe). His coefficients and mine will be  very different. 
> 
> I had an antenna outdoors. It got many sat’s all the  time. Now I have one 
> indoors. It’s not getting lots of sats all the time. My  old coefficients 
> are not going to be my new coefficients. 
> 
> No magic  bullet, you have to do the work. 
> 
> Bob
> 
>> On Oct 20, 2014, at  1:20 PM, Brian Lloyd <brian at lloyd.aero> wrote:
>> 
>> On Mon,  Oct 20, 2014 at 6:48 AM, Bob Camp <kb8tq at n1k.org> wrote:
>> 
>>> Hi
>>> 
>>> We tend to focus on this or that  enhanced feature in a piece of code. It
> ’s
>>> fun to talk about.  That’s not what keeps most designs from doing what 
> they
>>> should. By  focusing on this rather than the testing required, we set 
> people
>>> up to fail. If you start off the project believing you mostly need  
> fancy
>>> code when you mostly need long term testing instead, you hit  a wall 
> pretty
>>> fast. Setting up for one is not at all the same as  setting up for the 
> other.
>>> 
>> 
>> Sounds to me like the  hardware and code are pretty straight-forward. The
>> difference comes  from the terms and coefficients in the PLL loop filter 
> and
>> those need  to be optimized for each OCXO. There appear to be here a 
> handful
>> of  people who have a pretty good idea of what those coefficients should  
> be
>> for various well-known OCXOs out there.
>> 
>> So why not  do the GPSD hardware, software, and then provide the
>> coefficients that  will get a handful of the more popular OCXOs available
>> out there to  within a decade of optimum, certainly closer than what one
>> would be  talking about by just bolting x-random OCXO onto an LTE-lite? I
>> suspect there would be a market in the time-nut world for such a  
> critter.
>> 
>> -- 
>> Brian Lloyd
>> Lloyd  Aviation
>> 706 Flightline Drive
>> Spring Branch, TX 78070
>> brian at lloyd.aero
>> +1.210.802-8FLY (1.210.802-8359)
>> _______________________________________________
>> time-nuts mailing list  -- time-nuts at febo.com
>> To unsubscribe, go to  
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the  instructions  there.
> 
> _______________________________________________
> time-nuts  mailing list -- time-nuts at febo.com
> To unsubscribe, go to  
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the  instructions there.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.




More information about the time-nuts mailing list