[time-nuts] GPS and Rubidium frequency standards and noise question (new...

[Rex]

Said,

Thanks for the info and congrats on the stats from the Jackson Labs stuff.

You mentioned the older HP Z3801. I wonder if you (or others) happen to 
have comparison numbers on the Z3816A with the MTI 260 oscillator or the 
Z3805 with (I think) the same oscillator. I thought I heard the MTI 260 
might be slightly better than the 10811 but can't recall if anyone here 
actually made measurements,

Not to say that any of the HP Z---- stuff is seen for sale often these 
days. But I have one of each of the above mentioned.

Guess it may be close to the *time* where I should take the *time* to 
build or set up a system where I could get trustworthy measurements of 
these *timing* quality things myself. I keep reading but never seem to 
find the time to actually do it.

-Rex


On 6/3/2012 1:46 AM, SAIDJACK at aol.com wrote:
> Jerry, Chris,
>
> it's all relative, while the Lpro may be a good Rb standard, it's phase
> noise is not that good really. You list:
>
>     -96dBc/Hz @ 10Hz, -138dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz  offsets
>
> For the Lpro. The new Jackson Labs Technologies LN CSAC GPSDO with SC-cut
> phase noise and ADEV filter achieves the following:
>
>     -138dBc/Hz @ 10Hz, -148dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz  offsets.
>
> At 1Hz offset we see -105dBc/Hz and better on that unit.
>
> The FEI-5680A Rubidium that we discussed here some time ago has a much
> worse phase noise plot of course, because the 10MHz is generated digitally
> through a DDS, not a 10MHz crystal oscillator..
>
> It all depends on your requirements, and your budget.. I think the Z3801A
> (or it's brother the 58503A) is still one of the lowest phase noise and
> best ADEV GPSDO on the surplus market if you get a typical unit, and if you can
>   locate one.
>
> bye,
> Said
>
> From: Jerry Mulchin<_jmulchin at cox.net_ (mailto:jmulchin at cox.net)>
> Date: June 2,  2012 16:44:14 PDT
> To: Discussion of precise time and frequency  measurement
> <_time-nuts at febo.com_ (mailto:time-nuts at febo.com)>
> Subject:  Re: [time-nuts] GPS and Rubidium frequency standards and noise
> question  (newbie).
> Reply-To: Discussion of precise time and frequency  measurement
> <_time-nuts at febo.com_ (mailto:time-nuts at febo.com)>
>
>
>
>
>
> Chris,
>
> To answer your question  regarding using a Rubidium standard as a frequency
>   reference
> for your  Transverters.
>
> GPS really has nothing to do  the main requirement regarding Phase Noise
> and  your
> Transceivers. But the 10MHz oscillator inside the  Rubidium standard is the
> item
> that will be the Phase Noise  problem if you get the wrong Rubidium
> standard. There
> are  cheap Rubidiums and there are good Rubidium standards to  consider.
>
> An LPRO-101 is actually a very  good Rubidium standard, and exhibits Phase
> Noise
> values of  -96dBc/Hz @ 10Hz, -138dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz  offsets
> from carrier. This is what I use for my 10GHz  Transverter reference, but I
> don't lock it
> to GPS when in  the field. LPRO-101's can be gotten pretty  reasonably.
>
> Locking the LPRO-101 to a GPS  will require more support circuitry, and
> most of the
> folks  on this list can help you with that.
>
> Also,  Thunderbolt GPS disciplined units are nice, but I do not know the
> Phase  Noise
> numbers of a typical Thunderbolt unit. Others here  probably know the
> answer to that.
>
> The  important thing to remember is you don't what to use 10MHz oscillators
> that  have
> poor Phase Noise performance as it will effect your  weak signal capability
> if you use
> a poor Phase Noise  oscillator.
>
> Jerry
>
> At  03:05 PM 6/2/2012, you wrote:
>
> If you want a frequency reference.  There is nothing better than GPS.  In
>
>
> fact it you bought a Rubidium you would  still need the GPS so you could
>
>
> calibrate its  frequency.
>
>
>
>
>
> Some GPSes might be noisy but then you can  lock a good double oven crystal
>
>
> oscillator to it and have what they call a  "GPS disciplined crystal
>
>
> oscillator or "GPSDO".
>
>
>
>
>
>
>
>
>
>
>
> On Sat, Jun 2, 2012 at 2:57 PM, Chris Wilson<_chris at chriswilson.tv_
> (mailto:chris at chriswilson.tv)>   wrote:
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> I am looking to get a frequency standard  for my amateur radio shack,
>
>
>
>
> initially for verifying test gear  readings, but later as a standard
>
>
>
>
> to lock receiver and transmitter  oscillators to. I was going to buy
>
>
>
>
> a GPS frequency standard but a friend  warned me these may have noise
>
>
>
>
> issues when I come to use it with an  oscillator in RX / TX
>
>
>
>
> applications. It's not something I had  considered, so what's the
>
>
>
>
> score here please? Should I not buy a GPS  standard? Thanks. Any
>
>
>
>
> links to known safe suitable purchase  sources from personal
>
>
>
>
> experience welcome, either here or by PM  or e-mail. I am in the UK.
>
>
>
>
>
>
>
>
>
> --
>
>
>
>
> Best  regards,
>
>
>
>
> Chris Wilson  _mailto:chris at chriswilson.tv_ (mailto:chris at chriswilson.tv)
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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