[time-nuts] Re: About 10 MHz Optical Distro

[Bob kb8tq]

Hi

Ok so what is “decent” performance? 

Is -150 dbc/ Hz “floor” good enough? it is for some stuff ….

Is -130 dbc/ Hz at 10 Hz a requirement? 

Is -100 dbc / Hz at 1 Hz the target? 

Is 1x10^-12 at 1 second “good enough” ADEV?

How about 1x10^-13 at 10 seconds …..

Keep in mind that these are system floor numbers. The real signal 
“as delivered” isn’t going to ever be as good as the system floor.

You could easily move any of those phase numbers 20 db one way or the other.
The ADEV could go up or down by at least two orders of magnitude. The numbers
would still be “decent” by some definitions. 

Bob

> On Aug 29, 2021, at 3:24 PM, Lux, Jim <jim at luxfamily.com> wrote:
> 
> On 8/29/21 12:13 PM, CFO wrote:
>> From here
>> https://forums.xilinx.com/t5/Serial-Transceivers/Sending-10Mhz-clock-over-Fiber/td-p/1026390 
>> 
>> They suggest these
>> 
>> *** SNIP ***
>> what length do you need to send over ?
>> 
>> this sort of stuff is a LOT cheaper and more rugged, and more than capable of sending 10 MHz clock
>> 
>> Cable
>> https://uk.farnell.com/broadcom-limited/hfbr-rus100z/cable-fibre-optic-1-fibre/dp/1247714 <https://uk.farnell.com/broadcom-limited/hfbr-rus100z/cable-fibre-optic-1-fibre/dp/1247714> 
>> 
>> Drivers
>> http://www.farnell.com/datasheets/1812660.pdf?_ga=2.29282815.2110613125.1570030173-2072545025.1569659196 <http://www.farnell.com/datasheets/1812660.pdf?_ga=2.29282815.2110613125.1570030173-2072545025.1569659196> 
>> 
>> and you just drive it with TTL.
> 
> 
> Yeah, but those are piece parts.  What would be nice is if a cheap "box" could be found - ideally (for 10 MHz) BNC in/out and fiber connector with a wall wart for power. Maybe this a good idea for a TAPR project if someone was willing to do the design (!)
> 
> There's probably plenty of applications out there in amateur radio land for a inexpensive RF over optical link with "decent" performance (defined however).
> 
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