[time-nuts] RFX GPSDO - Anybody played with one of these?

[bg at lysator.liu.se]

> On 10/2/12 10:35 PM, bg at lysator.liu.se wrote:
>>> On 10/2/12 2:36 PM, SAIDJACK at aol.com wrote:
>>>> Hello Paul,
>>>>
>>>> thanks much for the feedback!
>>>>
>>>> Yes, we think we have identified a nice combination of oscillators,
>>>> GPS,
>>>> and firmware that seems to work pretty well. The GPSTCXO units cannot
>>>> be
>>>> compared to a lower cost $150 Thunderbolt in terms of phase noise or
>>>> stability
>>>> of course, and they have CMOS 10MHz outputs, but then the  TB's cost
>>>> around
>>>> $1500 new I guess.
>>>>
>>>> We think the GPSTCXO's and LC_XO type units will work quite well
>>>> wherever
>>>> standard OCXO's are used today, and power/size/weight are an  issue.
>>>>
>>>
>>>
>>> Intriguing.. Can it handle the Doppler, etc., for a cubesat in LEO?
>>> (7km/s)  The total Doppler isn't usually the issue (the GPS satellites
>>> are moving faster, after all), but the receiver may not work for high
>>> velocities, high altitudes?
>>
>> GPS SVs moves at around 4km/s, but nevertheless there are still COCOM
>> limits implemented in nearly all receivers (never break both 504m/s and
>> 18km height)
>>
>
> Doh. of course. higher is slower
>
>
> In any case, though, nothing stops Jackson Labs from selling one that is
> export controlled and has no restrictions.

Not more than some paperwork for Jackson Labs to source a "no limit"
uBlox. And then checking that the uBlox actually performs as expected in
that environment. Well, I am not sure the doppler search range is wide
enough in a standard firmware. (+-4km/s vs +-11km/s relative vel.)

On the "black sheep" Javad online shop they quote an extra $1k for this.


--

    Björn