[time-nuts] BVA Oscillaotrs

Bob Camp lists at rtty.us
Fri Aug 30 16:49:23 UTC 2013


Hi

The BVA's were specifically targeted at very good ADEV performance. It's sort of a left brain / right brain sort of thing. The time people look at ADEV and "close in" is usually 1 second and sometimes 0.1 second. The frequency people look at phase noise and "really low" is often 10 Hz, and occasionally 1 Hz. The two measurements do sort of correspond to each other, but not entirely. One second ADEV at X does not directly map to 1 Hz phase noise at a level of Y. 

The frequency guys want to womp the signal up to something high, and their math is easy if they start with phase noise. The timing people use different math, and phase noise doesn't really do it for them. ADEV sort of works for timing applications. There are other more specific measures for certain timing needs. 

Bob

On Aug 30, 2013, at 12:31 PM, Tom Knox <actast at hotmail.com> wrote:

> I may be mistaken but I thought the very close in Ultra Low Phase Noise was what the BVA name was built on, even more then Aging. But with the performance advances of Wenzel and others over the past few decades it is difficult to justify the price.
> 
> Thomas Knox
> 
> Ascent Concepts and Technology
> 
> 4475 Whitney Place
> Boulder Colorado 80305
> 
> 1-303-554-0307
> 
>> From: lists at rtty.us
>> Date: Fri, 30 Aug 2013 12:13:54 -0400
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] BVA Oscillaotrs
>> 
>> Hi
>> 
>> Just to be very clear:
>> 
>> a spec guarantee of < 1.0 x 10^-13 at any tau between 1 second and 100 seconds is a very different thing than "generally below 1.0x10^-12 at 1 second".
>> 
>> That said, not all BVA's meet that spec. 
>> 
>> Bob
>> 
>> 
>> On Aug 30, 2013, at 11:52 AM, Said Jackson <saidjack at aol.com> wrote:
>> 
>>> Steve,
>>> 
>>> 10E-013 means 1E-012. But the BVAs run in the low xE-013, about 10x better than that. And they are specifically designed to give great ADEV from at least 1s to 30s and more.
>>> 
>>> Agreed, its very easy to find fantastic phase noise performance from NEL, Pascal, Wenzel and others. That (-180dBc noise floor etc) seems to be no big deal these days, even though a very good Pascal ocxo will still cost as much as four CSACs or more.
>>> 
>>> Please give some examples of oscillators that were designed specifically for ADEV performance and can be ordered with specific ADEV parameters or are known to have these kinds of performance levels typically, I don't know of many.. Maybe 1 out of 10 HP 10811 will have ADEV in the low xE-013 as far as I have seen. Tom Van Back has a nice treatise on the ADEV of a large number of 10811's he measured in his Z38xx gpsdos, only some are truly great.
>>> 
>>> Thanks,
>>> Said
>>> 
>>> Sent From iPhone
>>> 
>>> On Aug 30, 2013, at 8:21, "Martyn Smith" <martyn at ptsyst.com> wrote:
>>> 
>>>> Hello,
>>>> 
>>>> Today many manufacturers are producing 10 MHz oscillators that offer many
>>>> advantages over BVA.
>>>> 
>>>> Phase noise of <  -116 dBc @ 1 Hz with a -175 dBc noise floor, ageing of 5 x
>>>> 10E-9 per month and a G sensitivity of 5 x 10E-11 /g in all axis is
>>>> available on a new product.
>>>> 
>>>> Also the short term Allan variance is in the low parts in 10E-13 for one
>>>> second.
>>>> 
>>>> It seems to me the only real advantage of BVA is the long term ageing and
>>>> this can easily be sorted out by locking to a superior standard.
>>>> 
>>>> Best Regards
>>>> 
>>>> Steve 
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