[time-nuts] GPS and Rubidium frequency standards and noise question (new...
Said Jackson
saidjack at aol.com
Sun Jun 3 19:33:03 UTC 2012
hello Rex,
from what I have seen the lowest noise is available on the Z3801 with 10811. I also have a Z3815 with E1938A oscillator, but the 3801 is much less noisy and more stable. Don't have a 3816 or 3805 to test against.
Keep in mind that there is a large performance variation from unit to unit as can be seen in TVB's Z3801A performance plots..
there are a good number of Z3801As modified to be 58503As on Ebay now. Got one from Yinxh some time ago, and that unit took over one year to fully settle down! Now I am consistently getting xE-013 ADEV from 0.1s to a couple 100s out of it. PN is excellent on that unit too.
bye,
Said
Sent From iPhone
On Jun 3, 2012, at 2:21, Rex <rexa at sonic.net> wrote:
> 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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