Re: [Flexradio] DIP OCXO for SDR
Jim Yes very interesting stuff and we would get control to tame them! Could not figure out the $ on these things. Eric2 http://www.temex.net/temex/product/crystal/pdf/qem77d.pdf Thanks Eric -Original Message- From: Jim Lux [mailto:[EMAIL PROTECTED] Sent: Sunday, January 08, 2006 1:08 PM To: John Ackermann N8UR; Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR At 06:50 AM 1/8/2006, John Ackermann N8UR wrote: >I'm traveling for a few days and don't have all my stuff handy, but >Gerald pointed me to a device from (I think) Silicon Industries in Texas >that looks very promising. They have VCXOs up to 400MHz that have some >sort of on-board divider/synthesizer/nco so they can deliver any >frequency in range with short lead time. The phase noise doesn't look >too bad, either. It's the part I'm focusing on right now for the >Reflock unit. I want to say the part number is something like Si520, >but that may be wrong. You might also look at the MCXO (Microprocessor Controlled Crystal Oscillator). I believe Q-Tech is one vendor.
Re: [Flexradio] DIP OCXO for SDR
At 06:50 AM 1/8/2006, John Ackermann N8UR wrote: I'm traveling for a few days and don't have all my stuff handy, but Gerald pointed me to a device from (I think) Silicon Industries in Texas that looks very promising. They have VCXOs up to 400MHz that have some sort of on-board divider/synthesizer/nco so they can deliver any frequency in range with short lead time. The phase noise doesn't look too bad, either. It's the part I'm focusing on right now for the Reflock unit. I want to say the part number is something like Si520, but that may be wrong. You might also look at the MCXO (Microprocessor Controlled Crystal Oscillator). I believe Q-Tech is one vendor.
Re: [Flexradio] DIP OCXO for SDR
John Yes thanks. Just Googled this have not read the specs but looks interesting. http://www.silabs.com/tgwWebApp/public/web_content/products/Optical/Frequenc y_Control/en/Si530-50.htm I guess we have been posting about the SDR stability as long as I have been around, maybe amongst all of us we can come up with something really slick. There are enuff folks interested! Eric -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Sunday, January 08, 2006 9:50 AM To: Eric Ellison Cc: 'Tim Ellison'; [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR I'm traveling for a few days and don't have all my stuff handy, but Gerald pointed me to a device from (I think) Silicon Industries in Texas that looks very promising. They have VCXOs up to 400MHz that have some sort of on-board divider/synthesizer/nco so they can deliver any frequency in range with short lead time. The phase noise doesn't look too bad, either. It's the part I'm focusing on right now for the Reflock unit. I want to say the part number is something like Si520, but that may be wrong. John Eric Ellison said the following on 01/07/2006 11:08 PM: > Tim > > Thanks. I swear that Gerald said the current VF part was sine wave output. I > saw the posts about the Greenray a while back and just don't know. This is > the first time in my searches that I found a 200 mhz VC part which is > available without horrific lead times and no quantity one. If the Crystek > part will work in our external closed loop design to drive the SDR > accurately then I'm for giving it a shot. That price is not bad either. At > times I had seen $80 + parts and they were not low phase noise, or voltage > controlled, just +/- 25 ppm TC parts. Although this is a 50 ppm part I think > that I saw it could be pulled +/- 500 ppm. > > Thanks for the response. > > Comments? > > Eric2 > > > -Original Message- > From: Tim Ellison [mailto:[EMAIL PROTECTED] > Sent: Saturday, January 07, 2006 10:32 PM > To: Eric Ellison; John Ackermann N8UR > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: RE: [Flexradio] DIP OCXO for SDR > > Eric, > > The VF VCXO listed below has a max frequency at 200 MHz. The XO > currently in use, the VF 161 has a max frequency of 300 MHz. Using a > device at either end of its rated frequency may suffer from precision > and/or accuracy errors. > > The Crystek is much closer, but the output is a sine wave rather than > PECL(positive emitter coupled logic) which is the output of the current > XO. I am not sure if this will make a difference or not with the > devices being designed. > > I did find this VCXO that is very close to the VP161 from Greenray, but > I received some less than satisfactory comments about the company > > http://greenrayindustries.com/library/ZT620.pdf > > -Tim > --- > Tim Ellison ( [EMAIL PROTECTED] ) > Integrated Technical Services ( http://www.itsco.com ) > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison > Sent: Saturday, January 07, 2006 9:01 PM > To: 'Eric Ellison'; 'John Ackermann N8UR' > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > John (and others on this thread) > > Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering > with > low phase noise. The VF 960/961. I could not find any ready sources for > this > part and did not request sample or quote. However, it is a pretty nice > piece. > > > http://www.mfelectronics.com/products/vcxo/ > > > I decided to go back out and do my occasional search for an available > part > with low phase noise and 200 mhz VC. > > Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip > and > $58 smt. > > See PDF. > > http://www.crystek.com/spec-sheets/CCO-083_085.pdf > http://www.mouser.com/catalog/624/656.pdf > > If we are talking about temp stabilizing and disciplining external to > the > radio, these might be good considerations for the conventional (not > computer > or FPGA aided) GPS - 10 mhz phase locking system. > > Someone could take a look and see if the specs are acceptable. > > Eric2 > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison > Sent: Friday, January 06, 2006 4:17 PM > To: 'John Ackermann N8UR' > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > John > > Yes! Gerald HAS really moved a lot of lives with something that actually > works, i
Re: [Flexradio] DIP OCXO for SDR
John, It's Silicon Laboratories. http://www2.silabs.com/tgwWebApp/public/web_content/products/Optical/Frequen cy_Control/en/Si530-50.htm 73, Bob, K5KDN -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John Ackermann N8UR Sent: Sunday, January 08, 2006 8:50 AM To: Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR I'm traveling for a few days and don't have all my stuff handy, but Gerald pointed me to a device from (I think) Silicon Industries in Texas that looks very promising. They have VCXOs up to 400MHz that have some sort of on-board divider/synthesizer/nco so they can deliver any frequency in range with short lead time. The phase noise doesn't look too bad, either. It's the part I'm focusing on right now for the Reflock unit. I want to say the part number is something like Si520, but that may be wrong. John Eric Ellison said the following on 01/07/2006 11:08 PM: > Tim > > Thanks. I swear that Gerald said the current VF part was sine wave output. I > saw the posts about the Greenray a while back and just don't know. This is > the first time in my searches that I found a 200 mhz VC part which is > available without horrific lead times and no quantity one. If the Crystek > part will work in our external closed loop design to drive the SDR > accurately then I'm for giving it a shot. That price is not bad either. At > times I had seen $80 + parts and they were not low phase noise, or voltage > controlled, just +/- 25 ppm TC parts. Although this is a 50 ppm part I think > that I saw it could be pulled +/- 500 ppm. > > Thanks for the response. > > Comments? > > Eric2 > > > -Original Message- > From: Tim Ellison [mailto:[EMAIL PROTECTED] > Sent: Saturday, January 07, 2006 10:32 PM > To: Eric Ellison; John Ackermann N8UR > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: RE: [Flexradio] DIP OCXO for SDR > > Eric, > > The VF VCXO listed below has a max frequency at 200 MHz. The XO > currently in use, the VF 161 has a max frequency of 300 MHz. Using a > device at either end of its rated frequency may suffer from precision > and/or accuracy errors. > > The Crystek is much closer, but the output is a sine wave rather than > PECL(positive emitter coupled logic) which is the output of the current > XO. I am not sure if this will make a difference or not with the > devices being designed. > > I did find this VCXO that is very close to the VP161 from Greenray, but > I received some less than satisfactory comments about the company > > http://greenrayindustries.com/library/ZT620.pdf > > -Tim > --- > Tim Ellison ( [EMAIL PROTECTED] ) > Integrated Technical Services ( http://www.itsco.com ) > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison > Sent: Saturday, January 07, 2006 9:01 PM > To: 'Eric Ellison'; 'John Ackermann N8UR' > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > John (and others on this thread) > > Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering > with > low phase noise. The VF 960/961. I could not find any ready sources for > this > part and did not request sample or quote. However, it is a pretty nice > piece. > > > http://www.mfelectronics.com/products/vcxo/ > > > I decided to go back out and do my occasional search for an available > part > with low phase noise and 200 mhz VC. > > Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip > and > $58 smt. > > See PDF. > > http://www.crystek.com/spec-sheets/CCO-083_085.pdf > http://www.mouser.com/catalog/624/656.pdf > > If we are talking about temp stabilizing and disciplining external to > the > radio, these might be good considerations for the conventional (not > computer > or FPGA aided) GPS - 10 mhz phase locking system. > > Someone could take a look and see if the specs are acceptable. > > Eric2 > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison > Sent: Friday, January 06, 2006 4:17 PM > To: 'John Ackermann N8UR' > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > John > > Yes! Gerald HAS really moved a lot of lives with something that actually > works, is available, and works very well! It sure has spawned a LOT of > interesting projects and experimentation. > > I agree totally that we should 'brainstorm' a solution for getting the > 200 > mhz off or on, or around, and o
Re: [Flexradio] DIP OCXO for SDR
I'm traveling for a few days and don't have all my stuff handy, but Gerald pointed me to a device from (I think) Silicon Industries in Texas that looks very promising. They have VCXOs up to 400MHz that have some sort of on-board divider/synthesizer/nco so they can deliver any frequency in range with short lead time. The phase noise doesn't look too bad, either. It's the part I'm focusing on right now for the Reflock unit. I want to say the part number is something like Si520, but that may be wrong. John Eric Ellison said the following on 01/07/2006 11:08 PM: > Tim > > Thanks. I swear that Gerald said the current VF part was sine wave output. I > saw the posts about the Greenray a while back and just don't know. This is > the first time in my searches that I found a 200 mhz VC part which is > available without horrific lead times and no quantity one. If the Crystek > part will work in our external closed loop design to drive the SDR > accurately then I'm for giving it a shot. That price is not bad either. At > times I had seen $80 + parts and they were not low phase noise, or voltage > controlled, just +/- 25 ppm TC parts. Although this is a 50 ppm part I think > that I saw it could be pulled +/- 500 ppm. > > Thanks for the response. > > Comments? > > Eric2 > > > -Original Message- > From: Tim Ellison [mailto:[EMAIL PROTECTED] > Sent: Saturday, January 07, 2006 10:32 PM > To: Eric Ellison; John Ackermann N8UR > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: RE: [Flexradio] DIP OCXO for SDR > > Eric, > > The VF VCXO listed below has a max frequency at 200 MHz. The XO > currently in use, the VF 161 has a max frequency of 300 MHz. Using a > device at either end of its rated frequency may suffer from precision > and/or accuracy errors. > > The Crystek is much closer, but the output is a sine wave rather than > PECL(positive emitter coupled logic) which is the output of the current > XO. I am not sure if this will make a difference or not with the > devices being designed. > > I did find this VCXO that is very close to the VP161 from Greenray, but > I received some less than satisfactory comments about the company > > http://greenrayindustries.com/library/ZT620.pdf > > -Tim > --- > Tim Ellison ( [EMAIL PROTECTED] ) > Integrated Technical Services ( http://www.itsco.com ) > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison > Sent: Saturday, January 07, 2006 9:01 PM > To: 'Eric Ellison'; 'John Ackermann N8UR' > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > John (and others on this thread) > > Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering > with > low phase noise. The VF 960/961. I could not find any ready sources for > this > part and did not request sample or quote. However, it is a pretty nice > piece. > > > http://www.mfelectronics.com/products/vcxo/ > > > I decided to go back out and do my occasional search for an available > part > with low phase noise and 200 mhz VC. > > Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip > and > $58 smt. > > See PDF. > > http://www.crystek.com/spec-sheets/CCO-083_085.pdf > http://www.mouser.com/catalog/624/656.pdf > > If we are talking about temp stabilizing and disciplining external to > the > radio, these might be good considerations for the conventional (not > computer > or FPGA aided) GPS - 10 mhz phase locking system. > > Someone could take a look and see if the specs are acceptable. > > Eric2 > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison > Sent: Friday, January 06, 2006 4:17 PM > To: 'John Ackermann N8UR' > Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > John > > Yes! Gerald HAS really moved a lot of lives with something that actually > works, is available, and works very well! It sure has spawned a LOT of > interesting projects and experimentation. > > I agree totally that we should 'brainstorm' a solution for getting the > 200 > mhz off or on, or around, and or back into the SDR-1000. Something > fairly > flexible and not too difficult to accomplish. > > I don't think that any of this is in conflict with others, and nothing > is > really 'fractionating' the mass of folks in spite of 'parallel' projects > going on. If anything we are getting some crosspollination. At this > point >
Re: [Flexradio] DIP OCXO for SDR
Tim Thanks. I swear that Gerald said the current VF part was sine wave output. I saw the posts about the Greenray a while back and just don't know. This is the first time in my searches that I found a 200 mhz VC part which is available without horrific lead times and no quantity one. If the Crystek part will work in our external closed loop design to drive the SDR accurately then I'm for giving it a shot. That price is not bad either. At times I had seen $80 + parts and they were not low phase noise, or voltage controlled, just +/- 25 ppm TC parts. Although this is a 50 ppm part I think that I saw it could be pulled +/- 500 ppm. Thanks for the response. Comments? Eric2 -Original Message- From: Tim Ellison [mailto:[EMAIL PROTECTED] Sent: Saturday, January 07, 2006 10:32 PM To: Eric Ellison; John Ackermann N8UR Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: RE: [Flexradio] DIP OCXO for SDR Eric, The VF VCXO listed below has a max frequency at 200 MHz. The XO currently in use, the VF 161 has a max frequency of 300 MHz. Using a device at either end of its rated frequency may suffer from precision and/or accuracy errors. The Crystek is much closer, but the output is a sine wave rather than PECL(positive emitter coupled logic) which is the output of the current XO. I am not sure if this will make a difference or not with the devices being designed. I did find this VCXO that is very close to the VP161 from Greenray, but I received some less than satisfactory comments about the company http://greenrayindustries.com/library/ZT620.pdf -Tim --- Tim Ellison ( [EMAIL PROTECTED] ) Integrated Technical Services ( http://www.itsco.com ) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Saturday, January 07, 2006 9:01 PM To: 'Eric Ellison'; 'John Ackermann N8UR' Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR John (and others on this thread) Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering with low phase noise. The VF 960/961. I could not find any ready sources for this part and did not request sample or quote. However, it is a pretty nice piece. http://www.mfelectronics.com/products/vcxo/ I decided to go back out and do my occasional search for an available part with low phase noise and 200 mhz VC. Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip and $58 smt. See PDF. http://www.crystek.com/spec-sheets/CCO-083_085.pdf http://www.mouser.com/catalog/624/656.pdf If we are talking about temp stabilizing and disciplining external to the radio, these might be good considerations for the conventional (not computer or FPGA aided) GPS - 10 mhz phase locking system. Someone could take a look and see if the specs are acceptable. Eric2 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Friday, January 06, 2006 4:17 PM To: 'John Ackermann N8UR' Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR John Yes! Gerald HAS really moved a lot of lives with something that actually works, is available, and works very well! It sure has spawned a LOT of interesting projects and experimentation. I agree totally that we should 'brainstorm' a solution for getting the 200 mhz off or on, or around, and or back into the SDR-1000. Something fairly flexible and not too difficult to accomplish. I don't think that any of this is in conflict with others, and nothing is really 'fractionating' the mass of folks in spite of 'parallel' projects going on. If anything we are getting some crosspollination. At this point having gone about as far as we can go with ECO's in this hardware, we are just 'branching out' into associated areas, where former focus was investigating how to directly improve the SDR-1000. Any comments from readers as to how we actually pull the VF osc, buffer it? Parts? Schematics? Block diagrams. Designs (not talk!). Thanks Eric2 -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Friday, January 06, 2006 9:16 AM To: Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Eric Ellison wrote: [ everything trimmed ] It sounds like there are several groups doing a lot of interesting things with FGPAs that extend way beyond just frequency stability. I think that's really great, and thank Gerald for creating such a great base for creative people to play. From my (and TAPR's) perspective, we want to do a Reflock-based design because it will have a broader use than just the SDR-1000. For example, with a 64MHz VCXO, it can work with the Ettus Research USRP software radio. I can also see it serving as an external clock for a sound card to eliminate that sou
Re: [Flexradio] DIP OCXO for SDR
Eric, The VF VCXO listed below has a max frequency at 200 MHz. The XO currently in use, the VF 161 has a max frequency of 300 MHz. Using a device at either end of its rated frequency may suffer from precision and/or accuracy errors. The Crystek is much closer, but the output is a sine wave rather than PECL(positive emitter coupled logic) which is the output of the current XO. I am not sure if this will make a difference or not with the devices being designed. I did find this VCXO that is very close to the VP161 from Greenray, but I received some less than satisfactory comments about the company http://greenrayindustries.com/library/ZT620.pdf -Tim --- Tim Ellison ( [EMAIL PROTECTED] ) Integrated Technical Services ( http://www.itsco.com ) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Saturday, January 07, 2006 9:01 PM To: 'Eric Ellison'; 'John Ackermann N8UR' Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR John (and others on this thread) Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering with low phase noise. The VF 960/961. I could not find any ready sources for this part and did not request sample or quote. However, it is a pretty nice piece. http://www.mfelectronics.com/products/vcxo/ I decided to go back out and do my occasional search for an available part with low phase noise and 200 mhz VC. Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip and $58 smt. See PDF. http://www.crystek.com/spec-sheets/CCO-083_085.pdf http://www.mouser.com/catalog/624/656.pdf If we are talking about temp stabilizing and disciplining external to the radio, these might be good considerations for the conventional (not computer or FPGA aided) GPS - 10 mhz phase locking system. Someone could take a look and see if the specs are acceptable. Eric2 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Friday, January 06, 2006 4:17 PM To: 'John Ackermann N8UR' Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR John Yes! Gerald HAS really moved a lot of lives with something that actually works, is available, and works very well! It sure has spawned a LOT of interesting projects and experimentation. I agree totally that we should 'brainstorm' a solution for getting the 200 mhz off or on, or around, and or back into the SDR-1000. Something fairly flexible and not too difficult to accomplish. I don't think that any of this is in conflict with others, and nothing is really 'fractionating' the mass of folks in spite of 'parallel' projects going on. If anything we are getting some crosspollination. At this point having gone about as far as we can go with ECO's in this hardware, we are just 'branching out' into associated areas, where former focus was investigating how to directly improve the SDR-1000. Any comments from readers as to how we actually pull the VF osc, buffer it? Parts? Schematics? Block diagrams. Designs (not talk!). Thanks Eric2 -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Friday, January 06, 2006 9:16 AM To: Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Eric Ellison wrote: [ everything trimmed ] It sounds like there are several groups doing a lot of interesting things with FGPAs that extend way beyond just frequency stability. I think that's really great, and thank Gerald for creating such a great base for creative people to play. From my (and TAPR's) perspective, we want to do a Reflock-based design because it will have a broader use than just the SDR-1000. For example, with a 64MHz VCXO, it can work with the Ettus Research USRP software radio. I can also see it serving as an external clock for a sound card to eliminate that source of frequency uncertainty. So, I don't see any conflict at all between what we're doing and the other approaches. The one SDR1k specific item I'd like to see, whether TAPR produces it or Gerald does, is a "civilized" board that will plug into the reference oscillator socket to allow a better interface to an external signal. I've started looking into that and we'll work with Gerald to figure out how best to offer that. It's mainly a matter of finding a buffer/level converter chip that will take a single-ended input and convert it to a differential signal at the right level for the DDS chip (suggestions welcome; I've started researching the chipmaker sites, but haven't found an obvious answer yet). 73, John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-ra
Re: [Flexradio] DIP OCXO for SDR
John (and others on this thread) Magnus - SM4RWI mailed me off list of a Valpey Fisher 200 VCXO offering with low phase noise. The VF 960/961. I could not find any ready sources for this part and did not request sample or quote. However, it is a pretty nice piece. http://www.mfelectronics.com/products/vcxo/ I decided to go back out and do my occasional search for an available part with low phase noise and 200 mhz VC. Newark is supplying a Crystek 200 mhz VCXO in stock for about $45 Dip and $58 smt. See PDF. http://www.crystek.com/spec-sheets/CCO-083_085.pdf http://www.mouser.com/catalog/624/656.pdf If we are talking about temp stabilizing and disciplining external to the radio, these might be good considerations for the conventional (not computer or FPGA aided) GPS - 10 mhz phase locking system. Someone could take a look and see if the specs are acceptable. Eric2 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Friday, January 06, 2006 4:17 PM To: 'John Ackermann N8UR' Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR John Yes! Gerald HAS really moved a lot of lives with something that actually works, is available, and works very well! It sure has spawned a LOT of interesting projects and experimentation. I agree totally that we should 'brainstorm' a solution for getting the 200 mhz off or on, or around, and or back into the SDR-1000. Something fairly flexible and not too difficult to accomplish. I don't think that any of this is in conflict with others, and nothing is really 'fractionating' the mass of folks in spite of 'parallel' projects going on. If anything we are getting some crosspollination. At this point having gone about as far as we can go with ECO's in this hardware, we are just 'branching out' into associated areas, where former focus was investigating how to directly improve the SDR-1000. Any comments from readers as to how we actually pull the VF osc, buffer it? Parts? Schematics? Block diagrams. Designs (not talk!). Thanks Eric2 -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Friday, January 06, 2006 9:16 AM To: Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Eric Ellison wrote: [ everything trimmed ] It sounds like there are several groups doing a lot of interesting things with FGPAs that extend way beyond just frequency stability. I think that's really great, and thank Gerald for creating such a great base for creative people to play. From my (and TAPR's) perspective, we want to do a Reflock-based design because it will have a broader use than just the SDR-1000. For example, with a 64MHz VCXO, it can work with the Ettus Research USRP software radio. I can also see it serving as an external clock for a sound card to eliminate that source of frequency uncertainty. So, I don't see any conflict at all between what we're doing and the other approaches. The one SDR1k specific item I'd like to see, whether TAPR produces it or Gerald does, is a "civilized" board that will plug into the reference oscillator socket to allow a better interface to an external signal. I've started looking into that and we'll work with Gerald to figure out how best to offer that. It's mainly a matter of finding a buffer/level converter chip that will take a single-ended input and convert it to a differential signal at the right level for the DDS chip (suggestions welcome; I've started researching the chipmaker sites, but haven't found an obvious answer yet). 73, John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
John Yes! Gerald HAS really moved a lot of lives with something that actually works, is available, and works very well! It sure has spawned a LOT of interesting projects and experimentation. I agree totally that we should 'brainstorm' a solution for getting the 200 mhz off or on, or around, and or back into the SDR-1000. Something fairly flexible and not too difficult to accomplish. I don't think that any of this is in conflict with others, and nothing is really 'fractionating' the mass of folks in spite of 'parallel' projects going on. If anything we are getting some crosspollination. At this point having gone about as far as we can go with ECO's in this hardware, we are just 'branching out' into associated areas, where former focus was investigating how to directly improve the SDR-1000. Any comments from readers as to how we actually pull the VF osc, buffer it? Parts? Schematics? Block diagrams. Designs (not talk!). Thanks Eric2 -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Friday, January 06, 2006 9:16 AM To: Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Eric Ellison wrote: [ everything trimmed ] It sounds like there are several groups doing a lot of interesting things with FGPAs that extend way beyond just frequency stability. I think that's really great, and thank Gerald for creating such a great base for creative people to play. From my (and TAPR's) perspective, we want to do a Reflock-based design because it will have a broader use than just the SDR-1000. For example, with a 64MHz VCXO, it can work with the Ettus Research USRP software radio. I can also see it serving as an external clock for a sound card to eliminate that source of frequency uncertainty. So, I don't see any conflict at all between what we're doing and the other approaches. The one SDR1k specific item I'd like to see, whether TAPR produces it or Gerald does, is a "civilized" board that will plug into the reference oscillator socket to allow a better interface to an external signal. I've started looking into that and we'll work with Gerald to figure out how best to offer that. It's mainly a matter of finding a buffer/level converter chip that will take a single-ended input and convert it to a differential signal at the right level for the DDS chip (suggestions welcome; I've started researching the chipmaker sites, but haven't found an obvious answer yet). 73, John
Re: [Flexradio] DIP OCXO for SDR
At 10:13 PM 1/5/2006, John Kolb wrote: Let's look at it a different way. You'all with higher math skills can see if this is a valid approach. Let's assume the 200 MHz signal 5 nS period) has +/-1 nS of jitter - very bad FM'ing +/- 40 MHz. If we divide it by 20 to get 10 MHz, we will still have 1 nS of jitter (assuming a perfect divider), but it's 1 nS of jitter on a 100 nS period signal, or +/-100 kHz FM'ing. Thus the phase noise at 1 MHz offset, for example, is considerably better. If you think of a typical phase noise distribution curve, you can see we have made it narrower for a particular DB level below peak. The phase noise reduction will be 6 db for each division by two. That's the usual rule of thumb: 20 log10(N) Different rules apply to the PLL, depending on it's design. Locking a 200 MHz oscillator to a 10 MHz reference, assume a wide loop bandwidth and no additional noise contributed by the electronics. If the 200 MHz is divided down with a digital divider, then for the loop to make the 200 MHz oscillator track the phase noise of the reference, the frequency excursions of the 200 MHz have to be 20 times as wide. This would cause the same phase noise multiplication as straight hormonic multiplication. If, however, the 10 MHz reference is applied to one input of a sampling type phase detector, and the 200 MHz applied to the other, the 200 MHz frequency excursions only have to match that of the reference, and thus the phase noise of the two will be about the same. If the 200 MHz were then divided in a digital divider, the resulting output could have phase noise better than the reference. Sounds like getting something for nothing :) Except that the Sampling phase detector doesn't quite work that way. A good way to think about an SPD is as a comb generator followed by a mixer. The jitter on the 200 MHz comb line that's mixing with the 200 MHz would be 20 times the jitter of the 10 MHz. In a more formalized sense, an idealized sampling process is taking the sampling impulses and multiplying it by the input signal to generate a series of samples at the frequency of the sampling signal. If you look in the frequency domain, you're convolving the fourier transform of the sampling signal (which is also a comb of impulses, at the sample rate and it's integer multiples) with the fourier transform of the input signal. So, any jitter (movement) in the lowest frequency impulse translates in to N*jitter in the Nth harmonic. Jim, W6RMK
Re: [Flexradio] DIP OCXO for SDR
Eric Ellison wrote: [ everything trimmed ] It sounds like there are several groups doing a lot of interesting things with FGPAs that extend way beyond just frequency stability. I think that's really great, and thank Gerald for creating such a great base for creative people to play. From my (and TAPR's) perspective, we want to do a Reflock-based design because it will have a broader use than just the SDR-1000. For example, with a 64MHz VCXO, it can work with the Ettus Research USRP software radio. I can also see it serving as an external clock for a sound card to eliminate that source of frequency uncertainty. So, I don't see any conflict at all between what we're doing and the other approaches. The one SDR1k specific item I'd like to see, whether TAPR produces it or Gerald does, is a "civilized" board that will plug into the reference oscillator socket to allow a better interface to an external signal. I've started looking into that and we'll work with Gerald to figure out how best to offer that. It's mainly a matter of finding a buffer/level converter chip that will take a single-ended input and convert it to a differential signal at the right level for the DDS chip (suggestions welcome; I've started researching the chipmaker sites, but haven't found an obvious answer yet). 73, John
Re: [Flexradio] DIP OCXO for SDR
Let's look at it a different way. You'all with higher math skills can see if this is a valid approach. Let's assume the 200 MHz signal 5 nS period) has +/-1 nS of jitter - very bad FM'ing +/- 40 MHz. If we divide it by 20 to get 10 MHz, we will still have 1 nS of jitter (assuming a perfect divider), but it's 1 nS of jitter on a 100 nS period signal, or +/-100 kHz FM'ing. Thus the phase noise at 1 MHz offset, for example, is considerably better. If you think of a typical phase noise distribution curve, you can see we have made it narrower for a particular DB level below peak. The phase noise reduction will be 6 db for each division by two. Multiplying up from 10 MHz to 200 MHz -- The formula 6 db phase noise increase for each doubling of freq is based on straight hormonic multiplication, not PLL multiplication. Assume a 10 MHz carrier with noise spurs 1 kHz each side of the carrier and 10 db lower than the carrier level. After freq multiplication by 20, the carrier will be at 200 MHz, and the spurs will be 20 kHz above and below the carrier, still 10 db lower. Likewise all the freqs of the phase noise spectrum have spread out in freq by a factor of 20 while keeping the same amplititude. Different rules apply to the PLL, depending on it's design. Locking a 200 MHz oscillator to a 10 MHz reference, assume a wide loop bandwidth and no additional noise contributed by the electronics. If the 200 MHz is divided down with a digital divider, then for the loop to make the 200 MHz oscillator track the phase noise of the reference, the frequency excursions of the 200 MHz have to be 20 times as wide. This would cause the same phase noise multiplication as straight hormonic multiplication. If, however, the 10 MHz reference is applied to one input of a sampling type phase detector, and the 200 MHz applied to the other, the 200 MHz frequency excursions only have to match that of the reference, and thus the phase noise of the two will be about the same. If the 200 MHz were then divided in a digital divider, the resulting output could have phase noise better than the reference. Sounds like getting something for nothing :) John KK6IL At 03:00 PM 1/4/2006, Jim Lux wrote: At 02:39 PM 1/4/2006, richard allen wrote: >Gentlemen, > >The DDS does Direct Digital Synthesis hence the name. It does not >divide >back to anything but runs an phase accumulation engine at 200 MHz (or >whatever >the clock rate) that produces output values to the dac at that rate. > >No division is performed. Actually, it does effectively do a division. For the purposes of argument, assume that we have a 200 MHz clock and are generating 10 MHz. Every 5 nanoseconds, we add 360/20 degrees to the phase accumulator, so that every 100 nanoseconds, we hit a multiple of 360, and have produced one cycle of the 10 MHz output. Considering just the MSB going to the DAC, you've got a square wave at 10 MHz, and that could just as easily be generated by dividing the 200MHz by 20. For what is a divide by N counter other than something that counts the input pulses and when it reaches N, it resets. Sure, there are some clevernesses involved if you are dividing by non-even numbers, and you want the output to be square wave with 50% duty cycle. From an goesinta/blackbox/goesoutta standpoint, they are identical... 200 MHz goes in one end and 200/20 MHz goes out the other. I think one could probably prove it algebraically. The key is the determinism in both forms: DDS or programmable divider; The output is entirely determined by the input, unlike other approaches approaches to frequency synthesis that might have different phase noise characteristics: a phase locked loop, for instance, has another oscillator in the black box which is synchronized to the external reference. Jim ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz -- Internal Virus Database is out-of-date. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.10.12/75 - Release Date: 8/17/2005
Re: [Flexradio] DIP OCXO for SDR
Cecil No you didn't miss. This was just for the Time Nuts! I punned it "It's about time"... Most of the Time Nuts didn't attend. I am going to make it much later Eastern time next time so Jim can get home in time to spend some time on Teamspeak. I think that would be his first time. I didn't realize it but we had a time conflict last night since the Rose Bowl committee picked our time to have the game. Flex-Radio-Friends weekly teamspeak forum is same time same station on Friday at 0100. See you next time. Eric2 -Original Message- From: KD5NWA [mailto:[EMAIL PROTECTED] Sent: Thursday, January 05, 2006 10:47 PM To: Eric Ellison Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR I must have missed the change in schedule of the Teamspeak meeting, is this change permanent? At 06:14 PM 1/5/2006, Eric Ellison wrote: >Folks > >Missed you on our Teamspeak session last night "It's about time"! > >Had a good discussion amongst a few people working on both the projects >(Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most >others! > >Bob K5KDN is working on a Timebase board, chassis etc and has a Jupiter and >nice 10 mhz Ovenized VCXO interfaced and building a board which will squat >down on the DIP connector on the Jupiter. > >On the Xylo side Bill - KD5TFD published a picture of his breadboard of the >Jupiter interfacing to the Xylo board, which will eventually pass >frequency/phase information back to the PowerSDR software. > >I am looking for more information on anyone who has produced a complete >circuit design published here several months ago by Tom Clark. Based on an >original design by Tom van Baak and enhanced by Tom Clark. > >This is really an inspired design! > >PIC header is published here without permission, however, I did not note a >copyright, and Tom made it available on the Forum several months ago. > >If it uses 10 MHZ this is the way to go! > >; -- >; >; Title: >; >; 10 MHz frequency divider >; >; Function: >; >; This PIC 16c84 program is designed to divide a 10 MHz frequency >; source down to 1 Hz (1 PPS). >; >; Since several extra output pins are available the program creates >; a total of 9 square wave outputs -- one for each frequency decade >; from 100 kHz to 0.001 Hz (1000 s). >; >; A STOP input and a 1 PPS synchronization input are also provided. >; Raising the STOP input high stops and resets the divider. The >; divider resumes on the leading edge of the 1 PPS SYNC input. The >; 1 PPS output will be synchronized to the 1 PPS SYNC input to less >; than 1.2 us (three PIC instructions at 10 MHz). >; >; The following chip schematic shows the assignment of each pin. >; >;-- -- >; 100 kHz <- RA2 |1--- 18| RA1 -> Red LED >; Green LED <- RA3 |2 17| RA0 <= Stop input >; 1PPS SYNC => T0CKI/RA4 |3 16| OSC1/CLKIN <= 10 MHz input >;+5 VDC -> /MCLR |4 15| OSC2/CLKOUT -- N/C >; GND -> Vss |5 16C84 14| Vdd <- +5 VDC >;10 kHz <- INT/RB0 |6 13| RB7 -> 1000 s >; 1 kHz <- RB1 |7 12| RB6 -> 100 s >; 100 Hz <- RB2 |8 11| RB5 -> 10 s >;10 Hz <- RB3 |9 10| RB4 -> 1 Hz / 1 PPS >;--- >; >; Implementation: >; >; To generate a 10 kHz square wave at 50% duty cycle an output pin >; must be flipped every 50 us (125 instructions at 10 MHz clock). >; This program does not use TMR0, the pre-scaler, or interrupts. >; Instead it relies on the fact that given an accurate 10 MHz clock >; each PIC instruction takes precisely 400 ns and the main loop has >; been designed to use exactly 125 instructions. >; >; The 100 kHz frequency (10 us period) is generated by setting an >; output pin on and off every 25 cycles. Since 25 is an odd number >; it is not possible for the PIC to generate this square wave with >; a 50% duty cycle. Instead a 20% duty cycle (5 cylcles on and 20 >; cycles off) was chosen for this frequency output. A total of 5 >; pairs of 100 kHz bit set/clear code are carefully interspersed >; within the 50 us main loop. >; >; Pins RA0 and RA4 are not used to drive a LED. RA4 is a Schmidt >; trigger input and O.C. output. It is used as the SYNC input. >; The data sheet says not to toggle RA0 under some conditions so >; it is used as the STOP input. >; >; Version: >; >; 1998-Aug-05, Version 4, tvb >; >; ----
Re: [Flexradio] DIP OCXO for SDR
I must have missed the change in schedule of the Teamspeak meeting, is this change permanent? At 06:14 PM 1/5/2006, Eric Ellison wrote: Folks Missed you on our Teamspeak session last night "It's about time"! Had a good discussion amongst a few people working on both the projects (Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most others! Bob K5KDN is working on a Timebase board, chassis etc and has a Jupiter and nice 10 mhz Ovenized VCXO interfaced and building a board which will squat down on the DIP connector on the Jupiter. On the Xylo side Bill - KD5TFD published a picture of his breadboard of the Jupiter interfacing to the Xylo board, which will eventually pass frequency/phase information back to the PowerSDR software. I am looking for more information on anyone who has produced a complete circuit design published here several months ago by Tom Clark. Based on an original design by Tom van Baak and enhanced by Tom Clark. This is really an inspired design! PIC header is published here without permission, however, I did not note a copyright, and Tom made it available on the Forum several months ago. If it uses 10 MHZ this is the way to go! ; -- ; ; Title: ; ; 10 MHz frequency divider ; ; Function: ; ; This PIC 16c84 program is designed to divide a 10 MHz frequency ; source down to 1 Hz (1 PPS). ; ; Since several extra output pins are available the program creates ; a total of 9 square wave outputs -- one for each frequency decade ; from 100 kHz to 0.001 Hz (1000 s). ; ; A STOP input and a 1 PPS synchronization input are also provided. ; Raising the STOP input high stops and resets the divider. The ; divider resumes on the leading edge of the 1 PPS SYNC input. The ; 1 PPS output will be synchronized to the 1 PPS SYNC input to less ; than 1.2 us (three PIC instructions at 10 MHz). ; ; The following chip schematic shows the assignment of each pin. ; ;-- -- ; 100 kHz <- RA2 |1--- 18| RA1 -> Red LED ; Green LED <- RA3 |2 17| RA0 <= Stop input ; 1PPS SYNC => T0CKI/RA4 |3 16| OSC1/CLKIN <= 10 MHz input ;+5 VDC -> /MCLR |4 15| OSC2/CLKOUT -- N/C ; GND -> Vss |5 16C84 14| Vdd <- +5 VDC ;10 kHz <- INT/RB0 |6 13| RB7 -> 1000 s ; 1 kHz <- RB1 |7 12| RB6 -> 100 s ; 100 Hz <- RB2 |8 11| RB5 -> 10 s ;10 Hz <- RB3 |9 10| RB4 -> 1 Hz / 1 PPS ;--- ; ; Implementation: ; ; To generate a 10 kHz square wave at 50% duty cycle an output pin ; must be flipped every 50 us (125 instructions at 10 MHz clock). ; This program does not use TMR0, the pre-scaler, or interrupts. ; Instead it relies on the fact that given an accurate 10 MHz clock ; each PIC instruction takes precisely 400 ns and the main loop has ; been designed to use exactly 125 instructions. ; ; The 100 kHz frequency (10 us period) is generated by setting an ; output pin on and off every 25 cycles. Since 25 is an odd number ; it is not possible for the PIC to generate this square wave with ; a 50% duty cycle. Instead a 20% duty cycle (5 cylcles on and 20 ; cycles off) was chosen for this frequency output. A total of 5 ; pairs of 100 kHz bit set/clear code are carefully interspersed ; within the 50 us main loop. ; ; Pins RA0 and RA4 are not used to drive a LED. RA4 is a Schmidt ; trigger input and O.C. output. It is used as the SYNC input. ; The data sheet says not to toggle RA0 under some conditions so ; it is used as the STOP input. ; ; Version: ; ; 1998-Aug-05, Version 4, tvb ; ; -- ; Using Microhip assembler. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Ackermann N8UR Sent: Thursday, January 05, 2006 1:49 PM To: [EMAIL PROTECTED] Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Great plan, John. I only had access to the 5052A for a day, so was pretty limited in what I could do; it's great that you'll be able to carry things forward. The one addition I would suggest is that you duplicate the DDS output measurements using the 10MHz source as well as the VF oscillator. That would add to my sketchy info about the effect of the multiplier on phase noise. I was not happy with the results I got, I think due to the way I was coupling out of the DDS, which was essentially a x1 scope probe with less-than-perfect grounding. After the fact, I redid the connection with a 50 ohm series resistor at U1 pin 6 (actually, mounted into a via on that line) and a short piece of RG-174 feeding a buffer amplifier. I think something li
Re: [Flexradio] DIP OCXO for SDR
John Thanks, yep, I really like that design. There is a great deal I think we can do on the FPGA and it may come to pass that we will do what you are suggesting and attempting. I feel certain that we will have enough le's to do it if we have the programmer to do it. We are still just bouncing around ideas for the FPGA, which will probably be a Cyclone II series in the final product. At the moment we are talking about a motherboard, daughtercard project case with 3 or 4 connectors to buss, raw power, inter card signals as well as FPGA connections across a 96 pin buss. Nothing has been decided regarding what will go on what card but the FPGA and HS USB might locically be on one card, audio processing on another etc. That way we will have the basis to use the FPGA for a lot of things, even yet to be determined. If our little 'project case' comes to fruition, it could even be used to house stand alone boards not even using the FPGA. Phil Harman - VK6APH and Bill Tracy KD5TFD are already working on the audio processing with the Wolfson A/D, although we will probably switch to TI parts for receive and transmit audio processing. Phil and Bill are already successfully digitizing the I/Q and passing it back to the computer over USB and it looks promising. Bill does have the Jupiter interfaced to the FPGA but is just beginning his exploration on that front. OTOH, Bob - K5KDN is working on a conventional design using the division process widely published, on a little circuit board designed to squat on or over the Jupiter GPS board. I think Bob's design and hardware will hit the street before something FPGA generated, and be quite welcome to SDR-1000 owners. I think that Tom and TVB's hack is a good way to go on that board. It is inexpensive, feature packed and the design and code exist for accurate time division and indicators. I just wondered if there was a more complete schematic for this PIC solution. Last night in brainstorming it appears that Bob will incorporate a USB connection to the board he is designing so we can talk to the Jupiter and the SDR software. Really no telling what way we could possibly go. If the Xylo for fun group hangs together and we get various contributions to Verilog and ideas a lot could be built in the little project case, including Oscilloscope, Spectrum Analyzer, high accuracy time base, SDR, etc. Thanks! Eric -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Thursday, January 05, 2006 8:04 PM To: Eric Ellison Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Sorry I couldn't join in the fun; just too many things going on. TVB's PIC divider is a really elegant hack, and works very well. I'm currently working on a project for TAPR for a universal divider (to take any common frequency standard output and drop it to 1pps) and started out planning to use the PIC design, but changed to a CPLD because that offered more flexibility (or at least a more comprehensible programming model) for what I was trying to do, which has more options than Tom considered. I suspect that if you're doing something with an FPGA or CPLD anyway, you'll have the gates available in that chip to do the division without having to add another device, so I'd consider that first before adding another block to the system. John Eric Ellison said the following on 01/05/2006 07:14 PM: > Folks > > Missed you on our Teamspeak session last night "It's about time"! > > Had a good discussion amongst a few people working on both the projects > (Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most > others! > > Bob K5KDN is working on a Timebase board, chassis etc and has a Jupiter and > nice 10 mhz Ovenized VCXO interfaced and building a board which will squat > down on the DIP connector on the Jupiter. > > On the Xylo side Bill - KD5TFD published a picture of his breadboard of the > Jupiter interfacing to the Xylo board, which will eventually pass > frequency/phase information back to the PowerSDR software. > > I am looking for more information on anyone who has produced a complete > circuit design published here several months ago by Tom Clark. Based on an > original design by Tom van Baak and enhanced by Tom Clark. > > This is really an inspired design! > > PIC header is published here without permission, however, I did not note a > copyright, and Tom made it available on the Forum several months ago. > > If it uses 10 MHZ this is the way to go! > > ; -- > ; > ; Title: > ; > ; 10 MHz frequency divider > ; > ; Function: > ; > ; This PIC 16c84 program is designed to divide a 10 MHz frequency > ; source down to 1 Hz (1 PPS). > ; > ; Since several
Re: [Flexradio] DIP OCXO for SDR
Jim Yeah, I've heard that, on the West Coast if you leave at 5 and have a 20 minute commute, you get home by 10. (smile) I'll push it up some in the future. I'm old and pretty much fade by 9 these days. Eric -Original Message- From: Jim Lux [mailto:[EMAIL PROTECTED] Sent: Thursday, January 05, 2006 8:17 PM To: Eric Ellison; 'John Ackermann N8UR'; [EMAIL PROTECTED] Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR At 04:14 PM 1/5/2006, Eric Ellison wrote: >Folks > >Missed you on our Teamspeak session last night "It's about time"! > >Had a good discussion amongst a few people working on both the projects >(Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most >others! And of course, people on the WestCoast who happen to have jobs that don't allow them to be home by 5PM James Lux, P.E. Spacecraft Radio Frequency Subsystems Group Flight Communications Systems Section Jet Propulsion Laboratory, Mail Stop 161-213 4800 Oak Grove Drive Pasadena CA 91109 tel: (818)354-2075 fax: (818)393-6875
Re: [Flexradio] DIP OCXO for SDR
At 04:14 PM 1/5/2006, Eric Ellison wrote: Folks Missed you on our Teamspeak session last night "It's about time"! Had a good discussion amongst a few people working on both the projects (Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most others! And of course, people on the WestCoast who happen to have jobs that don't allow them to be home by 5PM James Lux, P.E. Spacecraft Radio Frequency Subsystems Group Flight Communications Systems Section Jet Propulsion Laboratory, Mail Stop 161-213 4800 Oak Grove Drive Pasadena CA 91109 tel: (818)354-2075 fax: (818)393-6875
Re: [Flexradio] DIP OCXO for SDR
g-05, Version 4, tvb > ; > ; ------------------ > > ; Using Microhip assembler. > > > > > > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of John Ackermann N8UR > Sent: Thursday, January 05, 2006 1:49 PM > To: [EMAIL PROTECTED] > Cc: FlexRadio@flex-radio.biz > Subject: Re: [Flexradio] DIP OCXO for SDR > > Great plan, John. I only had access to the 5052A for a day, so was > pretty limited in what I could do; it's great that you'll be able to > carry things forward. > > The one addition I would suggest is that you duplicate the DDS output > measurements using the 10MHz source as well as the VF oscillator. That > would add to my sketchy info about the effect of the multiplier on phase > noise. > > I was not happy with the results I got, I think due to the way I was > coupling out of the DDS, which was essentially a x1 scope probe with > less-than-perfect grounding. After the fact, I redid the connection > with a 50 ohm series resistor at U1 pin 6 (actually, mounted into a via > on that line) and a short piece of RG-174 feeding a buffer amplifier. I > think something like that will give better results. > > By the way -- I looked at the AD9854 data sheet and it includes several > phase noise plots. From those, you would gather that there is a cost in > using the internal multiplier, but that it doesn't scale with DDS output > frequency. Also, from a quick read you could get the impression that > the phase noise of the reference clock doesn't really matter (within > reason, of course); they show the output phase noise plot without any > reference to the noise of the clock. > > 73, > John > > > [EMAIL PROTECTED] wrote: > >>This is cool. It's great to be able to discuss the nuances of what >>really goes on within our radios. Spreading the word is a very good >>thing. I checked out John's(N8UR) web site and I'm inspired. I have >>an E5052A Signal Source Analyzer setting here and plan to make a few >>measurements. >> >>Here's the plan so far: >> >> i. measure phase noise of a 10MHz crystal >> (it will probably be limited by the E5052A) >> ii. the 200MHz VF1611 >> iii. DDS output with VF1611 as the clock at: >> 1MHz >> 5MHz >> 10MHz >> 50MHz >> >>Anyone have any additional ideas? I'm all ears. >> >>73, >>k2ox >> >> >>-Original Message- >>From: richard allen [mailto:[EMAIL PROTECTED] >>Sent: Wednesday, January 04, 2006 5:39 PM >>To: John Ackermann N8UR >>Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz >>Subject: Re: [Flexradio] DIP OCXO for SDR >> >>Gentlemen, >> >>The DDS does Direct Digital Synthesis hence the name. It does not >>divide >>back to anything but runs an phase accumulation engine at 200 MHz (or >>whatever >>the clock rate) that produces output values to the dac at that rate. >> >>No division is performed. >> >>Richard W5SXD >> >>John Ackermann N8UR <[EMAIL PROTECTED]> wrote: >>(01/04/2006 16:09) >> >> >> >>>[EMAIL PROTECTED] wrote: >>> >>> >>>>First of all, any osc multiplied up widens its sidebands >>>>(phase noise) by the multiplication factor and the inverse is >>>>also true. The DDS does a 20X to 200MHz and a divide by 20 to >>>>get back to 10MHz. I guess it's academic at this point how >>>>much jitter is added by the DDS until someone measures it. >>> >>>You're only dividing back to 10MHz if that's the operating frequency. >>>At higher operating frequencies, the division doesn't equal the >>>multiplication (and of course, at lower ones it exceeds it). Measuring >>>the DDS output lets us see the phase noise where it counts, taking into >>>account both multiplication and division, rather than just at the >>>fundamental frequency of the reference. >>> >>> >>> >>>>Second, Rubidium standards are not intended to be used as local >>>>oscillators. They have terrible phase noise. They are intended >>>>to be used in timekeeping. It is their long term drift that >>>>excels, not short term phase noise. >>> >>>Agreed in general -- though there&#
Re: [Flexradio] DIP OCXO for SDR
Folks Missed you on our Teamspeak session last night "It's about time"! Had a good discussion amongst a few people working on both the projects (Xylo) and Flex. Guess the fantastic Texas - USC entertainment got most others! Bob K5KDN is working on a Timebase board, chassis etc and has a Jupiter and nice 10 mhz Ovenized VCXO interfaced and building a board which will squat down on the DIP connector on the Jupiter. On the Xylo side Bill - KD5TFD published a picture of his breadboard of the Jupiter interfacing to the Xylo board, which will eventually pass frequency/phase information back to the PowerSDR software. I am looking for more information on anyone who has produced a complete circuit design published here several months ago by Tom Clark. Based on an original design by Tom van Baak and enhanced by Tom Clark. This is really an inspired design! PIC header is published here without permission, however, I did not note a copyright, and Tom made it available on the Forum several months ago. If it uses 10 MHZ this is the way to go! ; -- ; ; Title: ; ; 10 MHz frequency divider ; ; Function: ; ; This PIC 16c84 program is designed to divide a 10 MHz frequency ; source down to 1 Hz (1 PPS). ; ; Since several extra output pins are available the program creates ; a total of 9 square wave outputs -- one for each frequency decade ; from 100 kHz to 0.001 Hz (1000 s). ; ; A STOP input and a 1 PPS synchronization input are also provided. ; Raising the STOP input high stops and resets the divider. The ; divider resumes on the leading edge of the 1 PPS SYNC input. The ; 1 PPS output will be synchronized to the 1 PPS SYNC input to less ; than 1.2 us (three PIC instructions at 10 MHz). ; ; The following chip schematic shows the assignment of each pin. ; ;-- -- ; 100 kHz <- RA2 |1--- 18| RA1 -> Red LED ; Green LED <- RA3 |2 17| RA0 <= Stop input ; 1PPS SYNC => T0CKI/RA4 |3 16| OSC1/CLKIN <= 10 MHz input ;+5 VDC -> /MCLR |4 15| OSC2/CLKOUT -- N/C ; GND -> Vss |5 16C84 14| Vdd <- +5 VDC ;10 kHz <- INT/RB0 |6 13| RB7 -> 1000 s ; 1 kHz <- RB1 |7 12| RB6 -> 100 s ; 100 Hz <- RB2 |8 11| RB5 -> 10 s ;10 Hz <- RB3 |9 10| RB4 -> 1 Hz / 1 PPS ;--- ; ; Implementation: ; ; To generate a 10 kHz square wave at 50% duty cycle an output pin ; must be flipped every 50 us (125 instructions at 10 MHz clock). ; This program does not use TMR0, the pre-scaler, or interrupts. ; Instead it relies on the fact that given an accurate 10 MHz clock ; each PIC instruction takes precisely 400 ns and the main loop has ; been designed to use exactly 125 instructions. ; ; The 100 kHz frequency (10 us period) is generated by setting an ; output pin on and off every 25 cycles. Since 25 is an odd number ; it is not possible for the PIC to generate this square wave with ; a 50% duty cycle. Instead a 20% duty cycle (5 cylcles on and 20 ; cycles off) was chosen for this frequency output. A total of 5 ; pairs of 100 kHz bit set/clear code are carefully interspersed ; within the 50 us main loop. ; ; Pins RA0 and RA4 are not used to drive a LED. RA4 is a Schmidt ; trigger input and O.C. output. It is used as the SYNC input. ; The data sheet says not to toggle RA0 under some conditions so ; it is used as the STOP input. ; ; Version: ; ; 1998-Aug-05, Version 4, tvb ; ; -- ; Using Microhip assembler. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Ackermann N8UR Sent: Thursday, January 05, 2006 1:49 PM To: [EMAIL PROTECTED] Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Great plan, John. I only had access to the 5052A for a day, so was pretty limited in what I could do; it's great that you'll be able to carry things forward. The one addition I would suggest is that you duplicate the DDS output measurements using the 10MHz source as well as the VF oscillator. That would add to my sketchy info about the effect of the multiplier on phase noise. I was not happy with the results I got, I think due to the way I was coupling out of the DDS, which was essentially a x1 scope probe with less-than-perfect grounding. After the fact, I redid the connection with a 50 ohm series resistor at U1 pin 6 (actually, mounted into a via on that line) and a short piece of RG-174 feeding a buffer amplifier. I think something like that will give better results. By the way -- I looked at the AD9854 data sheet and it includes several phase noise plot
Re: [Flexradio] DIP OCXO for SDR
The DDS does in fact divide the clock down. Let me give an example. To make it easier for me to explain, let's take the case of outputting a square wave. In this case the phase to amplitude lookup table has the first half of the table filled with ones and the second half filled with zeros. Now if you set the tuning word 'M' so that it jumps through the table twice the output is a square wave at the 1/2 the clock freq. If you set to tuning word so that it jumps through the table 4 times the output is 1/4 the clock rate and so on. Therefore the phase accumulator is actually a modulo-M counter that increments its value by 'M' each time it receives a clock pulse. The basic tuning equation is Fout = Fclk*(M/(2**n)), where M is the tuning word and n is the length in bits of the phase accumulator. Regards, k2ox -Original Message- From: richard allen [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 04, 2006 5:39 PM To: John Ackermann N8UR Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Gentlemen, The DDS does Direct Digital Synthesis hence the name. It does not divide back to anything but runs an phase accumulation engine at 200 MHz (or whatever the clock rate) that produces output values to the dac at that rate. No division is performed. Richard W5SXD John Ackermann N8UR <[EMAIL PROTECTED]> wrote: (01/04/2006 16:09) >[EMAIL PROTECTED] wrote: >> First of all, any osc multiplied up widens its sidebands >> (phase noise) by the multiplication factor and the inverse is >> also true. The DDS does a 20X to 200MHz and a divide by 20 to >> get back to 10MHz. I guess it's academic at this point how >> much jitter is added by the DDS until someone measures it. > >You're only dividing back to 10MHz if that's the operating frequency. >At higher operating frequencies, the division doesn't equal the >multiplication (and of course, at lower ones it exceeds it). Measuring >the DDS output lets us see the phase noise where it counts, taking into >account both multiplication and division, rather than just at the >fundamental frequency of the reference. > >> Second, Rubidium standards are not intended to be used as local >> oscillators. They have terrible phase noise. They are intended >> to be used in timekeeping. It is their long term drift that >> excels, not short term phase noise. > >Agreed in general -- though there's a wide difference in performance >between different types of Rb; some use FM modulation of the xtal, which >results in horrible phase noise, while others, like the 5065A, don't. >My post wasn't suggesting that you use an Rb as the primary reference. >However, the DDS output when driven by 10MHz shows the effect of the >multiplication, which is all I was trying to do. My web page also has a >plot of the HP 5065A phase noise at 10MHz, so you can see the difference >in noise between the raw and multiplied frequencies. > >John > >> http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has >> screenshots that show the phase noise at the output of the DDS for the >> standard 200MHz oscillator, and an HP Rubidium frequency standard at >> 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise >> hit caused by the multiplication. >> >> John >> >> ___ >> FlexRadio mailing list >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> >> > > >___ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
Great plan, John. I only had access to the 5052A for a day, so was pretty limited in what I could do; it's great that you'll be able to carry things forward. The one addition I would suggest is that you duplicate the DDS output measurements using the 10MHz source as well as the VF oscillator. That would add to my sketchy info about the effect of the multiplier on phase noise. I was not happy with the results I got, I think due to the way I was coupling out of the DDS, which was essentially a x1 scope probe with less-than-perfect grounding. After the fact, I redid the connection with a 50 ohm series resistor at U1 pin 6 (actually, mounted into a via on that line) and a short piece of RG-174 feeding a buffer amplifier. I think something like that will give better results. By the way -- I looked at the AD9854 data sheet and it includes several phase noise plots. From those, you would gather that there is a cost in using the internal multiplier, but that it doesn't scale with DDS output frequency. Also, from a quick read you could get the impression that the phase noise of the reference clock doesn't really matter (within reason, of course); they show the output phase noise plot without any reference to the noise of the clock. 73, John [EMAIL PROTECTED] wrote: This is cool. It's great to be able to discuss the nuances of what really goes on within our radios. Spreading the word is a very good thing. I checked out John's(N8UR) web site and I'm inspired. I have an E5052A Signal Source Analyzer setting here and plan to make a few measurements. Here's the plan so far: i. measure phase noise of a 10MHz crystal (it will probably be limited by the E5052A) ii. the 200MHz VF1611 iii. DDS output with VF1611 as the clock at: 1MHz 5MHz 10MHz 50MHz Anyone have any additional ideas? I'm all ears. 73, k2ox -Original Message- From: richard allen [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 04, 2006 5:39 PM To: John Ackermann N8UR Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Gentlemen, The DDS does Direct Digital Synthesis hence the name. It does not divide back to anything but runs an phase accumulation engine at 200 MHz (or whatever the clock rate) that produces output values to the dac at that rate. No division is performed. Richard W5SXD John Ackermann N8UR <[EMAIL PROTECTED]> wrote: (01/04/2006 16:09) [EMAIL PROTECTED] wrote: First of all, any osc multiplied up widens its sidebands (phase noise) by the multiplication factor and the inverse is also true. The DDS does a 20X to 200MHz and a divide by 20 to get back to 10MHz. I guess it's academic at this point how much jitter is added by the DDS until someone measures it. You're only dividing back to 10MHz if that's the operating frequency. At higher operating frequencies, the division doesn't equal the multiplication (and of course, at lower ones it exceeds it). Measuring the DDS output lets us see the phase noise where it counts, taking into account both multiplication and division, rather than just at the fundamental frequency of the reference. Second, Rubidium standards are not intended to be used as local oscillators. They have terrible phase noise. They are intended to be used in timekeeping. It is their long term drift that excels, not short term phase noise. Agreed in general -- though there's a wide difference in performance between different types of Rb; some use FM modulation of the xtal, which results in horrible phase noise, while others, like the 5065A, don't. My post wasn't suggesting that you use an Rb as the primary reference. However, the DDS output when driven by 10MHz shows the effect of the multiplication, which is all I was trying to do. My web page also has a plot of the HP 5065A phase noise at 10MHz, so you can see the difference in noise between the raw and multiplied frequencies. John http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has screenshots that show the phase noise at the output of the DDS for the standard 200MHz oscillator, and an HP Rubidium frequency standard at 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise hit caused by the multiplication. John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
This is cool. It's great to be able to discuss the nuances of what really goes on within our radios. Spreading the word is a very good thing. I checked out John's(N8UR) web site and I'm inspired. I have an E5052A Signal Source Analyzer setting here and plan to make a few measurements. Here's the plan so far: i. measure phase noise of a 10MHz crystal (it will probably be limited by the E5052A) ii. the 200MHz VF1611 iii. DDS output with VF1611 as the clock at: 1MHz 5MHz 10MHz 50MHz Anyone have any additional ideas? I'm all ears. 73, k2ox -Original Message- From: richard allen [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 04, 2006 5:39 PM To: John Ackermann N8UR Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Gentlemen, The DDS does Direct Digital Synthesis hence the name. It does not divide back to anything but runs an phase accumulation engine at 200 MHz (or whatever the clock rate) that produces output values to the dac at that rate. No division is performed. Richard W5SXD John Ackermann N8UR <[EMAIL PROTECTED]> wrote: (01/04/2006 16:09) >[EMAIL PROTECTED] wrote: >> First of all, any osc multiplied up widens its sidebands >> (phase noise) by the multiplication factor and the inverse is >> also true. The DDS does a 20X to 200MHz and a divide by 20 to >> get back to 10MHz. I guess it's academic at this point how >> much jitter is added by the DDS until someone measures it. > >You're only dividing back to 10MHz if that's the operating frequency. >At higher operating frequencies, the division doesn't equal the >multiplication (and of course, at lower ones it exceeds it). Measuring >the DDS output lets us see the phase noise where it counts, taking into >account both multiplication and division, rather than just at the >fundamental frequency of the reference. > >> Second, Rubidium standards are not intended to be used as local >> oscillators. They have terrible phase noise. They are intended >> to be used in timekeeping. It is their long term drift that >> excels, not short term phase noise. > >Agreed in general -- though there's a wide difference in performance >between different types of Rb; some use FM modulation of the xtal, which >results in horrible phase noise, while others, like the 5065A, don't. >My post wasn't suggesting that you use an Rb as the primary reference. >However, the DDS output when driven by 10MHz shows the effect of the >multiplication, which is all I was trying to do. My web page also has a >plot of the HP 5065A phase noise at 10MHz, so you can see the difference >in noise between the raw and multiplied frequencies. > >John > >> http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has >> screenshots that show the phase noise at the output of the DDS for the >> standard 200MHz oscillator, and an HP Rubidium frequency standard at >> 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise >> hit caused by the multiplication. >> >> John >> >> ___ >> FlexRadio mailing list >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> >> > > >___ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
Guys Much of this probably has been written for the third time on the various forums and reflectors (smile). Not a criticism by any means, since all this stuff is still sinkin' in. Time to do something! Reminder: "It's about time" Teamspeak forum at 0100 Z - 8 p.m. EDT" There is a temporary open forum section created for it. Thanks Eric -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of richard allen Sent: Wednesday, January 04, 2006 5:39 PM To: John Ackermann N8UR Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Gentlemen, The DDS does Direct Digital Synthesis hence the name. It does not divide back to anything but runs an phase accumulation engine at 200 MHz (or whatever the clock rate) that produces output values to the dac at that rate. No division is performed. Richard W5SXD John Ackermann N8UR <[EMAIL PROTECTED]> wrote: (01/04/2006 16:09) >[EMAIL PROTECTED] wrote: >> First of all, any osc multiplied up widens its sidebands >> (phase noise) by the multiplication factor and the inverse is >> also true. The DDS does a 20X to 200MHz and a divide by 20 to >> get back to 10MHz. I guess it's academic at this point how >> much jitter is added by the DDS until someone measures it. > >You're only dividing back to 10MHz if that's the operating frequency. >At higher operating frequencies, the division doesn't equal the >multiplication (and of course, at lower ones it exceeds it). Measuring >the DDS output lets us see the phase noise where it counts, taking into >account both multiplication and division, rather than just at the >fundamental frequency of the reference. > >> Second, Rubidium standards are not intended to be used as local >> oscillators. They have terrible phase noise. They are intended >> to be used in timekeeping. It is their long term drift that >> excels, not short term phase noise. > >Agreed in general -- though there's a wide difference in performance >between different types of Rb; some use FM modulation of the xtal, which >results in horrible phase noise, while others, like the 5065A, don't. >My post wasn't suggesting that you use an Rb as the primary reference. >However, the DDS output when driven by 10MHz shows the effect of the >multiplication, which is all I was trying to do. My web page also has a >plot of the HP 5065A phase noise at 10MHz, so you can see the difference >in noise between the raw and multiplied frequencies. > >John > >> http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has >> screenshots that show the phase noise at the output of the DDS for the >> standard 200MHz oscillator, and an HP Rubidium frequency standard at >> 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise >> hit caused by the multiplication. >> >> John >> >> ___ >> FlexRadio mailing list >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> >> > > >___ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
John Phase noise when multiplied by 20? I understand from others is that is not as bad as imagined. Eric -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, January 04, 2006 1:11 PM To: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR The SDR1000 can use clocks between 10MHz and 200MHz so long as when multiplied by an integer it equals 200 MHz. I use a 10MHz TCXO. 73, k2ox Isn't the oscillator in the SDR1000 a 200 MHz unit? http://www.bliley.com/index_005.htm says the N79A is available only up to 140 MHz. It also may be a little tall at 0.5 inches. I sure like the idea of a drop-in replacement. Are there any other OCXO or TCXO candidates? I'd be happy as a clam if I could always be within 20Hz of ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
Richard, that's a question I've been meaning to ask someone -- whether there's any phase noise improvement resulting from the (apparent) division of the clock signal by the DDS, or whether the output phase noise is always the same as, or worse than (due to imperfection in the DDS process), the reference. John richard allen said the following on 01/04/2006 05:39 PM: > Gentlemen, > > The DDS does Direct Digital Synthesis hence the name. It does not > divide > back to anything but runs an phase accumulation engine at 200 MHz (or > whatever > the clock rate) that produces output values to the dac at that rate. > > No division is performed. > > Richard W5SXD > > John Ackermann N8UR <[EMAIL PROTECTED]> wrote: > (01/04/2006 16:09) > > >>[EMAIL PROTECTED] wrote: >> >>>First of all, any osc multiplied up widens its sidebands >>>(phase noise) by the multiplication factor and the inverse is >>>also true. The DDS does a 20X to 200MHz and a divide by 20 to >>>get back to 10MHz. I guess it's academic at this point how >>>much jitter is added by the DDS until someone measures it. >> >>You're only dividing back to 10MHz if that's the operating frequency. >>At higher operating frequencies, the division doesn't equal the >>multiplication (and of course, at lower ones it exceeds it). Measuring >>the DDS output lets us see the phase noise where it counts, taking into >>account both multiplication and division, rather than just at the >>fundamental frequency of the reference. >> >> >>>Second, Rubidium standards are not intended to be used as local >>>oscillators. They have terrible phase noise. They are intended >>>to be used in timekeeping. It is their long term drift that >>>excels, not short term phase noise. >> >>Agreed in general -- though there's a wide difference in performance >>between different types of Rb; some use FM modulation of the xtal, which >>results in horrible phase noise, while others, like the 5065A, don't. >>My post wasn't suggesting that you use an Rb as the primary reference. >>However, the DDS output when driven by 10MHz shows the effect of the >>multiplication, which is all I was trying to do. My web page also has a >>plot of the HP 5065A phase noise at 10MHz, so you can see the difference >>in noise between the raw and multiplied frequencies. >> >>John >> >> >>>http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has >>>screenshots that show the phase noise at the output of the DDS for the >>>standard 200MHz oscillator, and an HP Rubidium frequency standard at >>>10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise >>>hit caused by the multiplication. >>> >>>John >>> >>>___ >>>FlexRadio mailing list >>>FlexRadio@flex-radio.biz >>>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >>> >>> >> >> >>___ >>FlexRadio mailing list >>FlexRadio@flex-radio.biz >>http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > > > >
Re: [Flexradio] DIP OCXO for SDR
At 02:39 PM 1/4/2006, richard allen wrote: Gentlemen, The DDS does Direct Digital Synthesis hence the name. It does not divide back to anything but runs an phase accumulation engine at 200 MHz (or whatever the clock rate) that produces output values to the dac at that rate. No division is performed. Actually, it does effectively do a division. For the purposes of argument, assume that we have a 200 MHz clock and are generating 10 MHz. Every 5 nanoseconds, we add 360/20 degrees to the phase accumulator, so that every 100 nanoseconds, we hit a multiple of 360, and have produced one cycle of the 10 MHz output. Considering just the MSB going to the DAC, you've got a square wave at 10 MHz, and that could just as easily be generated by dividing the 200MHz by 20. For what is a divide by N counter other than something that counts the input pulses and when it reaches N, it resets. Sure, there are some clevernesses involved if you are dividing by non-even numbers, and you want the output to be square wave with 50% duty cycle. From an goesinta/blackbox/goesoutta standpoint, they are identical... 200 MHz goes in one end and 200/20 MHz goes out the other. I think one could probably prove it algebraically. The key is the determinism in both forms: DDS or programmable divider; The output is entirely determined by the input, unlike other approaches approaches to frequency synthesis that might have different phase noise characteristics: a phase locked loop, for instance, has another oscillator in the black box which is synchronized to the external reference. Jim
Re: [Flexradio] DIP OCXO for SDR
Gentlemen, The DDS does Direct Digital Synthesis hence the name. It does not divide back to anything but runs an phase accumulation engine at 200 MHz (or whatever the clock rate) that produces output values to the dac at that rate. No division is performed. Richard W5SXD John Ackermann N8UR <[EMAIL PROTECTED]> wrote: (01/04/2006 16:09) >[EMAIL PROTECTED] wrote: >> First of all, any osc multiplied up widens its sidebands >> (phase noise) by the multiplication factor and the inverse is >> also true. The DDS does a 20X to 200MHz and a divide by 20 to >> get back to 10MHz. I guess it's academic at this point how >> much jitter is added by the DDS until someone measures it. > >You're only dividing back to 10MHz if that's the operating frequency. >At higher operating frequencies, the division doesn't equal the >multiplication (and of course, at lower ones it exceeds it). Measuring >the DDS output lets us see the phase noise where it counts, taking into >account both multiplication and division, rather than just at the >fundamental frequency of the reference. > >> Second, Rubidium standards are not intended to be used as local >> oscillators. They have terrible phase noise. They are intended >> to be used in timekeeping. It is their long term drift that >> excels, not short term phase noise. > >Agreed in general -- though there's a wide difference in performance >between different types of Rb; some use FM modulation of the xtal, which >results in horrible phase noise, while others, like the 5065A, don't. >My post wasn't suggesting that you use an Rb as the primary reference. >However, the DDS output when driven by 10MHz shows the effect of the >multiplication, which is all I was trying to do. My web page also has a >plot of the HP 5065A phase noise at 10MHz, so you can see the difference >in noise between the raw and multiplied frequencies. > >John > >> http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has >> screenshots that show the phase noise at the output of the DDS for the >> standard 200MHz oscillator, and an HP Rubidium frequency standard at >> 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise >> hit caused by the multiplication. >> >> John >> >> ___ >> FlexRadio mailing list >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> >> > > >___ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] DIP OCXO for SDR
[EMAIL PROTECTED] wrote: First of all, any osc multiplied up widens its sidebands (phase noise) by the multiplication factor and the inverse is also true. The DDS does a 20X to 200MHz and a divide by 20 to get back to 10MHz. I guess it's academic at this point how much jitter is added by the DDS until someone measures it. You're only dividing back to 10MHz if that's the operating frequency. At higher operating frequencies, the division doesn't equal the multiplication (and of course, at lower ones it exceeds it). Measuring the DDS output lets us see the phase noise where it counts, taking into account both multiplication and division, rather than just at the fundamental frequency of the reference. Second, Rubidium standards are not intended to be used as local oscillators. They have terrible phase noise. They are intended to be used in timekeeping. It is their long term drift that excels, not short term phase noise. Agreed in general -- though there's a wide difference in performance between different types of Rb; some use FM modulation of the xtal, which results in horrible phase noise, while others, like the 5065A, don't. My post wasn't suggesting that you use an Rb as the primary reference. However, the DDS output when driven by 10MHz shows the effect of the multiplication, which is all I was trying to do. My web page also has a plot of the HP 5065A phase noise at 10MHz, so you can see the difference in noise between the raw and multiplied frequencies. John http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has screenshots that show the phase noise at the output of the DDS for the standard 200MHz oscillator, and an HP Rubidium frequency standard at 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise hit caused by the multiplication. John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
[Flexradio] DIP OCXO for SDR
First of all, any osc multiplied up widens its sidebands (phase noise) by the multiplication factor and the inverse is also true. The DDS does a 20X to 200MHz and a divide by 20 to get back to 10MHz. I guess it's academic at this point how much jitter is added by the DDS until someone measures it. Second, Rubidium standards are not intended to be used as local oscillators. They have terrible phase noise. They are intended to be used in timekeeping. It is their long term drift that excels, not short term phase noise. 73, k2ox -Original Message- From: John Ackermann N8UR [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 04, 2006 3:16 PM To: Jim Lux Cc: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] DIP OCXO for SDR Jim Lux wrote: > At 10:11 AM 1/4/2006, [EMAIL PROTECTED] wrote: > >>The SDR1000 can use clocks between 10MHz and 200MHz so long as when >>multiplied by an integer it equals 200 MHz. I use a 10MHz TCXO. >> >>73, >>k2ox > > > However, when you multiply up using the internal VCO, the phase noise takes > a hit. You might wind up with poorer noise (but more accurate frequency) > multiplying up from a 10 MHz TCXO. http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has screenshots that show the phase noise at the output of the DDS for the standard 200MHz oscillator, and an HP Rubidium frequency standard at 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise hit caused by the multiplication. John
Re: [Flexradio] DIP OCXO for SDR
Jim Lux wrote: At 10:11 AM 1/4/2006, [EMAIL PROTECTED] wrote: The SDR1000 can use clocks between 10MHz and 200MHz so long as when multiplied by an integer it equals 200 MHz. I use a 10MHz TCXO. 73, k2ox However, when you multiply up using the internal VCO, the phase noise takes a hit. You might wind up with poorer noise (but more accurate frequency) multiplying up from a 10 MHz TCXO. http://www.febo.com/geekworks/sdr1k/sdr1k_phase/index.html has screenshots that show the phase noise at the output of the DDS for the standard 200MHz oscillator, and an HP Rubidium frequency standard at 10MHz multiplied by 20 in the DDS. You can clearly see the phase-noise hit caused by the multiplication. John
Re: [Flexradio] DIP OCXO for SDR
At 10:11 AM 1/4/2006, [EMAIL PROTECTED] wrote: The SDR1000 can use clocks between 10MHz and 200MHz so long as when multiplied by an integer it equals 200 MHz. I use a 10MHz TCXO. 73, k2ox However, when you multiply up using the internal VCO, the phase noise takes a hit. You might wind up with poorer noise (but more accurate frequency) multiplying up from a 10 MHz TCXO. Jim, W6RMK
Re: [Flexradio] DIP OCXO for SDR
The SDR1000 can use clocks between 10MHz and 200MHz so long as when multiplied by an integer it equals 200 MHz. I use a 10MHz TCXO. 73, k2ox Isn't the oscillator in the SDR1000 a 200 MHz unit? http://www.bliley.com/index_005.htm says the N79A is available only up to 140 MHz. It also may be a little tall at 0.5 inches. I sure like the idea of a drop-in replacement. Are there any other OCXO or TCXO candidates? I'd be happy as a clam if I could always be within 20Hz of
Re: [Flexradio] DIP OCXO for SDR
Isn't the oscillator in the SDR1000 a 200 MHz unit? http://www.bliley.com/index_005.htm says the N79A is available only up to 140 MHz. It also may be a little tall at 0.5 inches. I sure like the idea of a drop-in replacement. Are there any other OCXO or TCXO candidates? I'd be happy as a clam if I could always be within 20Hz of what the display says on 50 MHz. I don't need a GPS disciplined oscillator for that! On the other hand, I do need one for my microwave transverters so I've been following the GPS & oscillator discussions closely. 73.126 +/- 1e10-8 (sorry, it's not the "very best of 73's" ;-) Russell KB8U From: <[EMAIL PROTECTED]> Subject: [Flexradio] DIP OCXO for SDR To: Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="us-ascii" It looks like Bliley at www.bliley.com has single dip OCXO (N79A) that might drop right into the SDR1K oscillator socket. I found this a month ago, but decided to go with a TCXO from my junk box. The best one will give you 0.03 Hz at 10MHz operating freq. Take a look if you're interested. 73, k2ox
[Flexradio] DIP OCXO for SDR
It looks like Bliley at www.bliley.com has single dip OCXO (N79A) that might drop right into the SDR1K oscillator socket. I found this a month ago, but decided to go with a TCXO from my junk box. The best one will give you 0.03 Hz at 10MHz operating freq. Take a look if you're interested. 73, k2ox
