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@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 >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> 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 -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." R. Bacon "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 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com

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 <docdailey@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 >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> 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 -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > >

On 07/07/2012 03:10 PM, John Ackermann N8UR wrote: > 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. You can get pretty good 24,576 MHz TCXOs from CMAC with EFC input. One of those and a pair of dividers (to 16 kHz) and a fairly simple PI-loop PLL (2 resistors, 1 cap and an op-amp will suffice) should get you started. Getting the 48 kHz or 96 kHz out of the feedback divider comes for free if you realize that you should put the divide by 3 last in the chain, as the sequence of divide by two dividers will remain. Typical for a small CPLD or a standard PLL chip. Cheers, Magnus

Good: I'll modify my VHDL to include this. The last will be the 50% duty cycle divide-by-3 so that a 48KHz or 96KHz will be available. On Sat, Jul 7, 2012 at 3:47 PM, Magnus Danielson <magnus@rubidium.dyndns.org > wrote: > On 07/07/2012 03:10 PM, John Ackermann N8UR wrote: > >> 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. >> > > You can get pretty good 24,576 MHz TCXOs from CMAC with EFC input. One of > those and a pair of dividers (to 16 kHz) and a fairly simple PI-loop PLL (2 > resistors, 1 cap and an op-amp will suffice) should get you started. > Getting the 48 kHz or 96 kHz out of the feedback divider comes for free if > you realize that you should put the divide by 3 last in the chain, as the > sequence of divide by two dividers will remain. Typical for a small CPLD or > a standard PLL chip. > > Cheers, > Magnus > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

On Fri, Jul 6, 2012 at 10:26 PM, Don Latham <djl@montana.com> wrote: > 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. > Maybe look to see how this is done in commercial units. I think they use crystal oscillators that run at the word clock rate (or small multiple of it) This oscillator is phase locked to some reference and on the commercial units you can select the signal used as a reference. I don't think they use DDS or integer division of some unrelated frequency (like 10Mhz) > 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@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 > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> 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 -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > > -- > "Neither the voice of authority nor the weight of reason and argument > are as significant as experiment, for thence comes quiet to the mind." > R. Bacon > "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 > VOX 406-626-4304 > www.lightningforensics.com > www.sixmilesystems.com > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California