G
Gerhard Hoffmann
Guest
Am 14.09.2014 um 11:00 schrieb Bill Sloman:
looks like you need 2-way time transfer via DLLs and pseudo noise.
My current customer does just that from ground to space & back.
???
on page 8 I see the 3 and 4 GHz units break the -150 dBc/Hz
at 10 MHz offset, still linearly sinking towards the flat
noise floor.
Gerhard
On Sunday, 14 September 2014 16:58:17 UTC+10, Kevin Aylward wrote:
"John Larkin" wrote in message
news:1h291ahulit12anamhhlu27hrapque4mai@4ax.com...
snip
My box will receive a 10 MHz reference from the customer, from some
expensive Symmetrix GPS-disciplined thing. I'll also get a 1 PPS pulse
from that, and time-of-day data over Ethernet. It's my job to make
OC3-like optical data frames, at 155.52 MHz, that are exact in real
time to picoseconds.
Frequency locking isn't difficult. Time locking to picoseconds is.
http://www.slac.stanford.edu/econf/C011127/TUAP069.pdf
looks like you need 2-way time transfer via DLLs and pseudo noise.
My current customer does just that from ground to space & back.
What I will say though, is multiplying up by harmonic selection from LC
tanks gives orders of lower phase noise/jitter than a PLL.
PLL are useful when you want programmability in frequency and no inductors,
but 80 year old LC tank technology blows PLL away in terms of noise
performance. For example, meeting -150 dBc (30fs jitter) flat band phase
noise at 2.5GHz is, essentially, not achievable with PLL techniques, not
that I am giving anything away on one of my current projects...
http://cds.linear.com/docs/en/datasheet/6948f.pdf
shows only -100dBc/Hz on its performance curves.
???
on page 8 I see the 3 and 4 GHz units break the -150 dBc/Hz
at 10 MHz offset, still linearly sinking towards the flat
noise floor.
Gerhard