[time-nuts] disciplining sound card

[Don Latham]

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 <docdailey at gmail.com>
> 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
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>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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>


-- 
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
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"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
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