[time-nuts] UBLOX LEA-5T Programming?

[EWKehren at aol.com]

The 1 pps and the output frequencies are all derived from the same XO in  
the module. Up to 7 the difference in a T is that the saw tooth correction  
factor is brought out for correction purposes . 7 has a much higher XO  
frequency than the 5 so the saw tooth is smaller. So use a ublox 7 if you want  
to do a simple GPSPLL like James Miller described.  If you use the cheaper  M 
version you have to make sure you always have backup power since it does 
not  have a flash memory like the more expensive N version to memorize the  
setting Also stay away from 10 MHz out  better to use 200 or 400 KHz.  We have 
done a GPSPLL with ublox7 and Morion and got very good results. I have a  
board  if interested contact me off list.
Bert Kehren
 
 
In a message dated 10/9/2015 12:03:45 P.M. Eastern Daylight Time,  
cjaysharp at gmail.com writes:

I am  still learning and want to understand, if the PPS is good then why is
the  programmable output bad, as I understand it thus far, the PPS is
derived  from the same clock source or have I got that badly wrong?

On 9 October  2015 at 12:16, Bob Camp <kb8tq at n1k.org> wrote:

>  Hi
>
> Doing a GPSDO by locking to the awful 10 MHz output from  any of these GPS
> modules
> is not going to work very well. Given  the very long time constants
> involved in a GPSDO
> control loop,  doing it without code is going to be pretty difficult.
>
> A much  easier approach:
>
> Grab the GPS PPS and a scope. Use it to set  the Lucent boxes on 
frequency.
> Repeat the process
> once a  week.  The direct lock will flop around by (likely many) ppb.  
Your
> manual set will probably keep it
> under 1 ppb for a  week.
>
> Bob
>
> > On Oct 9, 2015, at 1:39 AM,  Perry Sandeen via time-nuts <
> time-nuts at febo.com> wrote:
>  >
> > Hi,
> > I have six of the older style (anodized  solid aluminum case) Lucent
> crystal oscillators that I’d like to turn  into simple 10 MHZ output
> GPSDO’s. I have some salvaged HP cases so I  can have a linear PS and all
> other stuff in one package.
> >  I’ve found two different choices of GPS relatively low cost units on
>  Ebay.
> > One is a LUCENT M12+ GPS Timing Receiver W/100 Hz  output  for  $19.99
> Item 171886538138.
> > The  other is a UBLOX LEA-5T GPS module dev board 1PPS /USB/RS232/ntp 
ser
>  with two 1 PPS outputs for $49.90. Item 251785217093.
> > IIRC, one  output of a Ublox can be set to a 10 MHz.
> > Can this model be set  to have a 10 MHz output and is it easily done 
from
> a PC? I have no  coding ability.
> > For more money I’d get a simpler phase detector  circuit, which is all
> I’m looking for. For less money I’d have to  build more circuitry.
> > A factor I don’t know is if the ublox is  that much better/newer to
> justify the price difference.
> > I  already have packed away two Oncore units with either a 1 KHz or 10
>  KHz output.
> > Suggestions welcomed.
> >   Regards,
> > Perrier
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-- 
Clint.

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