Hi
> On Jan 20, 2020, at 2:57 PM, Mark Haun <[email protected]> wrote: > > On Mon, 20 Jan 2020 14:22:41 -0500 > Bob kb8tq <[email protected]> wrote: >> On Jan 20, 2020, at 1:36 PM, Mark Haun <[email protected]> wrote: >>> The VFOV405 datasheet lists typical phase noise for 10- and 100-MHz >>> units. (Mine are 16.384 MHz.) In comparing the two oscillators, I >>> have used the 100-MHz "typical" numbers which they both state: >> >> So taking the 14 db from multiplication into account: >> >> >> VFO405 ABLNO >> >> 1K -126 -141 >> 10K -146 -160 >> 100K -149 -161 >> >> Looking at the plots on the ABLNO data sheets, the wide band noise >> gets down a bit below -161 on a “typical” basis. >> >> Locking an 80 MHz ABLNO to 16.384 is not going to be as easy as >> locking one to 16.000. Getting an ABLNO with an EFC at 16.384 x 5 may >> be a bit of a challenge. > > Agree except you were starting from the VFOV numbers for the 100-MHz > version. If you use their numbers for the 10-MHz version and add 20 dB > for an ideal 10x multiplication, for comparing with the ABLNO spec at > 100 MHz, you end up with > > offset VFOV405 @ 10M, ideal 10x multiply ABLNO @ 100 M > 10 -100 -88 > 100 -120 -118 > 1k -140 -141 > 10k -145 -160 > 100k -145 -161 If indeed -145 is “good enough” then you have moved out of the “good phase noise” region into fairly generic sort of specs. A “couple of dollar” oscillator will give you -145 sort of noise floors. The value of 12 db at 10 Hz offset is going to be pretty limited unless the application is very unusual. Bob > > so not bad apart from the raised floor. (I am assuming that an ideal 5x > multiplication on the 16.384-MHz version of the VFOV405 would yield a > similar comparison to an 80-MHz ABLNO.) > > Using this handy tool: https://rf-tools.com/jitter/ it looks like 0.5 > ps should be achievable as long as the floor is kept to -145 dBc/Hz > (integrating 10 Hz to 10 MHz). The multiplier scheme will need to > contribute very little residual noise far out. No idea how easy/hard > that will be. More than 0.5 ps jitter will start to degrade the ADC > performance significantly. > > Regards, > Mark > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
