[time-nuts] OT: xtal osc PN
lists at rtty.us
Sun Sep 19 02:39:07 UTC 2010
Is -195 dbc/Hz floor good enough or is it overkill?
Is -155 dbc/Hz at 100 Hz offset a requirement or is -40 dbc ok?
You need to quantify what you are after before deciding on an approach. Low noise means many different things to each of us.
On Sep 18, 2010, at 1:27 PM, francesco messineo <francesco.messineo at gmail.com> wrote:
> On 9/18/10, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
>> A simple PLL is not that complex these days. As long as you have fairly
>> high comparator frequency after dividing down the VCO and reference you
>> could get away fairly easilly. Standard programmable dividers in the TTL
>> family and a single chip for phase-comparator will work fairly well.
>> There is gazillions of examples among hams for this approach.
> sure, but I'd need to at least understand what's low noise and what's
> not again :-)
>>> -) if there were many others with my same needs, we'd probably find
>>> better to use a modern DDS (share the pcb making and someone who can
>>> do the soldering of such packages), instead, so far the low-VHF people
>>> aren't generally aware that better frontends are possible, you find
>>> lot of work in the HF receivers and next to nothing in the lower VHF
>>> where big signals and intermodulations come from broadcasts and not
>>> from other amateur stations!
>> Maybe the DDS board from the DMTD project would fit your needs?
> maybe, I didn't follow that thread, what DDS chip is used? What's the
> clock source?
> In this moment I'd pretty much like it fits my needs, also because of
> Rick's comment (I would order custom made xtals if it's not going to
> cost more than the rest of the parts and if I know what to order).
> Frank IZ8DWF
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