Hi Don --
The problem with the Clock-Block is that it can't generate exactly the
correct frequency in this case -- the closest it can get is several PPM
off. And, I'm not sure the phase noise/jitter from the Clock-Block is
good enough.
I don't know whether you could program a PIC to generate a precise
wordclock; the maximum output frequency you can get from either TADD-2
device is about 800 kHz, so it couldn't generate a 12 or 24 MHz
oscillator replacement frequency.
John
----
Don Latham said the following on 07/07/2012 01:26 AM:
Foe word rate generation from 10 MHz, perhaps the TAPR devices:
http://www.tapr.org/kits_clock-block.html
or:
http://www.tapr.org/kits_tadd-2.html
with a type D f/f to get a square wave?
generate your clock for cheap.
Don
Chris Albertson
There is a profesional "standard" for clock distribution for computer
audio
interfaces. They call it a "Word Clock" and it is usually distributed
over
75 ohm coax cable. It is common for a studio to have a master word
clock
generator and to use audio interfaces that accept an external clock.
Some
of these master clocks have rubidium or OCXO inside. Most can also PLL
to
any external clock
The trouble is that lower priced audio interfaces lack a "word clock"
input
and you'd need to get into something like this as a minimum to have that
feature
828mk3Hy <http://www.sweetwater.com/store/detail/828mk3Hy/>
So if you are going to hack a cheap consumer interface it might be a
better
hack to install a word clock input. At some point inside the interface
there MUST be a sample rate clock running at 44.1, 48, 96, 192
kilohertz.
Find then cut that trace and bring it out to a 75 ohm BNC connector.
Now
you have a standard pro level feature.
Now when you divide down your 10Mhz lab standard divide it to "word
rate"
and you only need to build the divider once and you can use it with any
audio interface that has word clock I/O.
Yes of course you can send 14.4356MHz or whatever but that is a one time
design and it will be different with every audio interface depending on
whatever TTL can oscillator the engineer used.
All that said. I have a "cheap" Presonus firewire audio interface that
has
S/PDIF input and it has the option to accept word clock over the fiber
s/pdif. Many low priced interfaces can do this. Then you happen to
have
a quality s/pdif device around you are set.
On Fri, Jul 6, 2012 at 12:05 PM, Bill Dailey <[email protected]>
wrote:
What if I post a schematic with a Lattice M4-64/32 CPLD? If you can
program
this CPLD I can send the .JED file, the schematic...
---------------------------------
I could probably get that done... would have to get a board made...
never
done it but could probably manage...some kind of usb blaster to
program
it. I presume the .jed is the code? I can solder for sure. Would I
be
able to look at the code so I can learn something?
--
Doc
Bill Dailey
KXØO
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
