[time-nuts] DS-1 from 10MHz
I'm running more than a few days late on mail, but my inclination would be to
order a custom programmed SI5355 from Silicon Labs for $5 - no minimum quantity
and 2 week turnaround. Admittedly the part is a qfn (SMT Quad Flat-pack
No-leads) but it is easy, can run off an external user provided reference
clock, and has reasonable jitter ('typically 50ps - not as good as an SI570 but
a whole lot better than an AD9851 DDS), and for a T1 clock should be perfectly
suitable.
From the Silabs page:
The Si5355 is a highly flexible clock generator capable of synthesizing four
completely non-integer related frequencies up to 200 MHz. The device has four
banks of outputs with each bank supporting two CMOS outputs at the same
frequency. Using Silicon Laboratories' patented MultiSynth fractional divider
technology, all outputs are guaranteed to have 0 ppm frequency synthesis error
regardless of configuration, enabling the replacement of multiple clock ICs and
crystal oscillators with a single device. Through a flexible web configuration
utility
called ClockBuilder™ (www.silabs.com/ClockBuilder), factory-customized
pincontrolled
Si5355 devices are available in two weeks without minimum order
quantity restrictions. The Si5355 supports up to three independent,
pin-selectable
device configurations, enabling one device to replace three separate clock ICs.
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Re: [time-nuts] DS-1 from 10MHz
Definitely a basement project. J.D. Bob Camp wrote: Hi A lot depends on weather this is a one off basement project or a commercial endeavor. If it's commercial, there are people who will sell you a packaged part that will do the 10 MHz to T1 conversion. Bob On Jul 4, 2010, at 10:38 PM, Hal Murray wrote: I would like to generate a DS-1 timing reference from 10 MHz, e.g a T-bolt. Thought someone here might be able to suggest a starting point. One approach is a PLL. You will have to divide 1.544 MHz by 193 and 10 MHz by 1250. If you want to use the TAPR Clock-Block, I think you will need something like a divide by 10 between the 10 MHz and the Clock-Block to get the numbers within range. I wonder if you could use a VCXO and fit all the logic in a tiny micro. It would probably need a few external parts to filter the PWM output. Maybe the filtering inside the VCXO would be good enough. Another approach is to use a DDS. Analog Devices makes the whole thing in one package, but the numbers don't work out exactly. How close to you need to be? With a 32 bit (binary) adder, you get 1544000.001158 MHz. With 48 bits you get 1543999.99989825. But you don't have to use a binary adder. You have 1000 Hz and you want 1544000 Hz, so you need to multiply by 1544000 and divide by 1000. That reduces to 193 / 1250. So add 193 each cycle using modulo 1250 addition. Each time it overflows, kick out a pulse. If you want a square wave output, divide by 625 and toggle the output on each overflow. That sort of logic fits well in a FPGA/CPLD. That will give you a clock that's locked to your input clock but with lots of jitter. (up to 1/2 clock off in each direction, so 100 ns peak-to-peak) You can run that through a low pass filter and/or feed the top bits into a sine table and on to a DAC. Note that isn't the standard ROM. You have to make a new table for each modulus and if you are using standard ROMs with binary addressing you will waste up to 1/2 of each ROM. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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. ___ 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. ___ 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.
Re: [time-nuts] DS-1 from 10MHz
Hi A lot depends on weather this is a one off basement project or a commercial endeavor. If it's commercial, there are people who will sell you a packaged part that will do the 10 MHz to T1 conversion. Bob On Jul 4, 2010, at 10:38 PM, Hal Murray wrote: > >>I would like to generate a DS-1 timing reference from 10 MHz, e.g a >> T-bolt. Thought someone here might be able to suggest a starting point. > > One approach is a PLL. You will have to divide 1.544 MHz by 193 and 10 MHz > by 1250. If you want to use the TAPR Clock-Block, I think you will need > something like a divide by 10 between the 10 MHz and the Clock-Block to get > the numbers within range. > > I wonder if you could use a VCXO and fit all the logic in a tiny micro. It > would probably need a few external parts to filter the PWM output. Maybe the > filtering inside the VCXO would be good enough. > > > Another approach is to use a DDS. Analog Devices makes the whole thing in > one package, but the numbers don't work out exactly. How close to you need > to be? With a 32 bit (binary) adder, you get 1544000.001158 MHz. With 48 > bits you get 1543999.99989825. > > But you don't have to use a binary adder. You have 1000 Hz and you want > 1544000 Hz, so you need to multiply by 1544000 and divide by 1000. That > reduces to 193 / 1250. So add 193 each cycle using modulo 1250 addition. > Each time it overflows, kick out a pulse. If you want a square wave output, > divide by 625 and toggle the output on each overflow. That sort of logic > fits well in a FPGA/CPLD. > > That will give you a clock that's locked to your input clock but with lots of > jitter. (up to 1/2 clock off in each direction, so 100 ns peak-to-peak) > > You can run that through a low pass filter and/or feed the top bits into a > sine table and on to a DAC. Note that isn't the standard ROM. You have to > make a new table for each modulus and if you are using standard ROMs with > binary addressing you will waste up to 1/2 of each ROM. > > -- > These are my opinions, not necessarily my employer's. I hate spam. > > > > > ___ > 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. > ___ 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.
Re: [time-nuts] DS-1 from 10MHz
> I would like to generate a DS-1 timing reference from 10 MHz, e.g a > T-bolt. Thought someone here might be able to suggest a starting point. One approach is a PLL. You will have to divide 1.544 MHz by 193 and 10 MHz by 1250. If you want to use the TAPR Clock-Block, I think you will need something like a divide by 10 between the 10 MHz and the Clock-Block to get the numbers within range. I wonder if you could use a VCXO and fit all the logic in a tiny micro. It would probably need a few external parts to filter the PWM output. Maybe the filtering inside the VCXO would be good enough. Another approach is to use a DDS. Analog Devices makes the whole thing in one package, but the numbers don't work out exactly. How close to you need to be? With a 32 bit (binary) adder, you get 1544000.001158 MHz. With 48 bits you get 1543999.99989825. But you don't have to use a binary adder. You have 1000 Hz and you want 1544000 Hz, so you need to multiply by 1544000 and divide by 1000. That reduces to 193 / 1250. So add 193 each cycle using modulo 1250 addition. Each time it overflows, kick out a pulse. If you want a square wave output, divide by 625 and toggle the output on each overflow. That sort of logic fits well in a FPGA/CPLD. That will give you a clock that's locked to your input clock but with lots of jitter. (up to 1/2 clock off in each direction, so 100 ns peak-to-peak) You can run that through a low pass filter and/or feed the top bits into a sine table and on to a DAC. Note that isn't the standard ROM. You have to make a new table for each modulus and if you are using standard ROMs with binary addressing you will waste up to 1/2 of each ROM. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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.
Re: [time-nuts] DS-1 from 10MHz
Perhaps. The DS-1 signal has a pulse-mask which is not square. And while the all "1"s AMI signal looks like 772 kHz, presumably the D4 or ESF frame would require some zero's in the 193d bit position. But your suggestion leads to a possible 2 stage solution. There are CSU/DSUs which accept an external TTL level clock. So perhaps use the tapr board to drive the CSU/DSU and let the CSU/DSU build the DS-1 frame. Thanks, J.D. Poul-Henning Kamp wrote: In message <97416.58969...@web30303.mail.mud.yahoo.com>, Stanley Reynolds write s: Couldn't you do the same thing much easier with the ICS525 chip ? Neat and convenient: http://tapr.org/kits_clock-block.html Poul-Henning I have a board that does this, I could send you. See Pictures here: www.n4iqt.com/fts4040/ds1 =A0 www.n4iqt.com/fts4040/ds1/FTSds1001.JPG www.n4iqt.com/fts4040/ds1/FTSds1002.JPG www.n4iqt.com/fts4040/ds1/FTSds1003.JPG Stanley - Original Message From: J.D. Schoedel To: Discussion of precise time and frequency measurement Sent: Sun, July 4, 2010 11:57:44 AM Subject: [time-nuts] DS-1 from 10MHz All, =A0 I would like to generate a DS-1 timing reference from 10 MHz, e.g a T-b= olt.=A0 = Thought someone here might be able to suggest a starting point. Thanks, J.D. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nu= ts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nu= ts and follow the instructions there. ___ 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.
Re: [time-nuts] DS-1 from 10MHz
In message <97416.58969...@web30303.mail.mud.yahoo.com>, Stanley Reynolds write s: Couldn't you do the same thing much easier with the ICS525 chip ? Neat and convenient: http://tapr.org/kits_clock-block.html Poul-Henning >I have a board that does this, I could send you. > >See Pictures here: > >www.n4iqt.com/fts4040/ds1 >=A0 >www.n4iqt.com/fts4040/ds1/FTSds1001.JPG > >www.n4iqt.com/fts4040/ds1/FTSds1002.JPG > >www.n4iqt.com/fts4040/ds1/FTSds1003.JPG > >Stanley > > > >- Original Message >From: J.D. Schoedel >To: Discussion of precise time and frequency measurement m> >Sent: Sun, July 4, 2010 11:57:44 AM >Subject: [time-nuts] DS-1 from 10MHz > >All, >=A0 I would like to generate a DS-1 timing reference from 10 MHz, e.g a T-b= >olt.=A0 = > >Thought someone here might be able to suggest a starting point. >Thanks, >J.D. > >___ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nu= >ts >and follow the instructions there. > > >___ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nu= >ts >and follow the instructions there. > -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [time-nuts] DS-1 from 10MHz
I have a board that does this, I could send you. See Pictures here: www.n4iqt.com/fts4040/ds1 www.n4iqt.com/fts4040/ds1/FTSds1001.JPG www.n4iqt.com/fts4040/ds1/FTSds1002.JPG www.n4iqt.com/fts4040/ds1/FTSds1003.JPG Stanley - Original Message From: J.D. Schoedel To: Discussion of precise time and frequency measurement Sent: Sun, July 4, 2010 11:57:44 AM Subject: [time-nuts] DS-1 from 10MHz All, I would like to generate a DS-1 timing reference from 10 MHz, e.g a T-bolt. Thought someone here might be able to suggest a starting point. Thanks, J.D. ___ 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. ___ 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.
[time-nuts] DS-1 from 10MHz
All, I would like to generate a DS-1 timing reference from 10 MHz, e.g a T-bolt. Thought someone here might be able to suggest a starting point. Thanks, J.D. ___ 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.
