[time-nuts] new GPSDO kit

Dave Brown tractorb at ihug.co.nz
Sat Apr 5 21:10:33 EDT 2014


Sounds like an ideal reference for a microwave hilltopping event.
DaveB, NZ
 (ZL3FJ)
----- Original Message ----- 
From: <SAIDJACK at aol.com>
To: <time-nuts at febo.com>
Sent: Sunday, April 06, 2014 6:19 AM
Subject: Re: [time-nuts] new GPSDO kit


> Hello Brooke,
>
>>>Can  you say more about what this means?
>>>"It  generates a low-noise 10MHz signal with typically better than
>>>1E-010 precision and accuracy (0.1ppb) on average"
>
> let me explain. I took some measurements over night, see attached files.
> This was done with the unit shielded from airflow and sitting on a bench, 
> and
> the time constant increased by a bit to account for the benign no-airflow
> environment.
>
> You can see that the ADEV at any time from 1s to 10,000s averages and
> beyond is about 1.3E-010 worst case. So you can assume that the  average
> accuracy (because of GPS being the absolute reference) and relative 
> precision (the
> ADEV around the average value) is about 1.xE-010 on a  typical unit.
>
> Also note that the second plot shows a standard deviation of the TI
> interval of 13.3ns which is significantly better than the 25ns spec.
>
> Lastly, the performance of 3E-012 at 10,000s is almost 3x better than 
> spec.
>
> This was a random unit I grabbed that had been sitting on a shelf for some
> months, and I only let it run for ~15 minutes after power-on before I
> started the measurement.
>
> This is one of the beautiful features of the TCXO we use: it does not
> require long retrace and warmup periods. It runs pretty much right out of 
> the
> box, even after months in storage. An OCXO based unit probably would have
> required 8+ hours to stabilize from its retrace after such a long 
> off-period.
> In fact this unit ran at only about 1.5ppb error before disciplining
> started, meaning the TCXO and our firmware kept that frequency accuracy 
> over
> several months on the shelf without power.
>
> So you could go to a work-site, set up the unit and wait about 15 minutes,
> then get a really clean, accurate, and stable reference signal.
>
> Hope that makes sense,
> Said
>
>
>
>
> In a message dated 4/4/2014 16:40:45 Pacific Daylight Time,
> brooke at pacific.net writes:
>
> Hi  Said:
>
> Can  you say more about what this means?
> "It generates a  low-noise 10MHz signal with typically better than 1E-010
> precision and  accuracy (0.1ppb) on average"
>
> Have Fun,
>
> Brooke  Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
>
> SAIDJACK at aol.com  wrote:
>> Hello everyone,
>>
>> sorry for the  plug, but we just announced a new $568 complete GPSDO
>> reference  kit.
>>
>> This unit is a tiny desktop unit with 10m  antenna, power supply, cables,
>> CD, and other accessories. It is a low  cost addition to our Fury GPSDO
> line,
>> and contains a really good  TCXO, a uBlox GPS receiver, and various power
>> options. I believe this  is the lowest-cost real GPSDO in mass production
>> available on the  market right now, and being a true GPSDO it has  some
> fairly
>> good  phase noise and stability specs.
>>
>>
> http://www.jackson-labs.com/assets/uploads/main/LC-XO-Plus_PressRelease.pdf
>>
>> bye,
>> Said
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