Re: [time-nuts] Choke Ring Pictures
Hi Brian! Nice work! /Björn > Several years back we had the discussion about choke ring antennas. > > Dr Thomas Clark - retired NASA - Goddard Space Flight Center - I believe > he was head of the VLBI project - made a simple choke ring antenna with > an electrical junction box. > > I made 3 sets using pie plates. I promised somebody the pictures and > forgot it until now. The pictures are hosted at > > http://kc0onr.com/Brian/_MG_0668.jpg > http://kc0onr.com/Brian/_MG_0669.jpg > > I made these units because were I lived was surrounded by mountains 3/4 > around my property and I was at 720 feet elevation and the mountains > varied from 1000 to 1200 feet. I had a problem that my receivers jumped > positions several times and I suspected a multi path problem. I made > the first antenna using some RF adsorbent material around the antenna. > Helped. After making the choke rings, the problem went away. The other > two units were used for carrier phase surveying. With the Motorola > Oncore VPZ unit and Waypoint's GrafNav software I could get resolution > down to a little under an inch. > > Brian KD4FM > > > > > > ___ > 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] Choke Ring Pictures
Just curious. Is this antenna under a cover or are there drain holes to let out the water when it rains? Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brian Kirby Sent: Saturday, March 13, 2010 10:24 PM To: Discussion of precise time and frequency measurement; Bill Clingan Subject: [time-nuts] Choke Ring Pictures Several years back we had the discussion about choke ring antennas. Dr Thomas Clark - retired NASA - Goddard Space Flight Center - I believe he was head of the VLBI project - made a simple choke ring antenna with an electrical junction box. I made 3 sets using pie plates. I promised somebody the pictures and forgot it until now. The pictures are hosted at http://kc0onr.com/Brian/_MG_0668.jpg http://kc0onr.com/Brian/_MG_0669.jpg I made these units because were I lived was surrounded by mountains 3/4 around my property and I was at 720 feet elevation and the mountains varied from 1000 to 1200 feet. I had a problem that my receivers jumped positions several times and I suspected a multi path problem. I made the first antenna using some RF adsorbent material around the antenna. Helped. After making the choke rings, the problem went away. The other two units were used for carrier phase surveying. With the Motorola Oncore VPZ unit and Waypoint's GrafNav software I could get resolution down to a little under an inch. Brian KD4FM ___ 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] Choke Ring Design for L1
The major flaw in that method is that it doesn't actually make measurements over the entire sphere. Unless you have an independent method of showing that the effective response to signals incident from underneath the antenna are small it also fails to measure the true response in the upper hemisphere. Before and after plots also don't solve that particular measurement problem. Bruce WarrenS wrote: Bruce wrote Those plots give little information about the antenna response to variations in SV elevation directly as the signal strength from theSV also varies with elevation. No account is taken of the SV signal variation with elevation. ws) Correct, but a really Silly comment. Of course for that you compare the before and after plots. BUT, In your zeal to find something to criticize no mater how small, you missed an important point again. These plots are examples that show the whole overall signal strength picture, which can be used to set the Elevation mask among MANY other things. ws *> WarrenS wrote: Bruce wrote: Only for your particular location and antenna. You have no actual idea of how the antenna response is affected by the presence of the cake tin, Those plots give little information about the antenna response to variations in SV elevation directly as the signal strength from the SV also varies with elevation. nor did you specify what sort of antenna you are using with it. (which is no surprise case they are made to be mounted on a metal body.) The latter are all patch antennas which don't work at all well without a ground plane (either an external one or a built in one). Even the thickness of the ground plane makes a difference to the antenna response: http://www.emtalk.com/tut_1.htm http://www.orbanmicrowave.com/The_Basics_Of_Patch_Antennas.pdf http://www.specemc.com/patch.asp http://piers.mit.edu/piersproceedings/download.php?file=cGllcnMyMDA5bW9zY293fDVQNV8xOTI2LnBkZnwwOTAzMTQwODAxMzA= http://ctvr.ie/docs/RF%20Pubs/IEEEVTC_2007_Investigation%20on%20Miniature%20Wideband%20Patch%20Antenna%20.pdf http://140.117.166.1/eehome/ISCOM2005/SubmitPaper/UploadPapers/ISCON05_00100.pdf A patch antenna at the bottom of a cake tin may not have much gain over the elevation range of interest. Your explanation of why this appears to work well is still nonsense. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. That is exactly what I did with the new Lady Heather, You may want to try it for yourself before your unfounded criticizing or look at the attached. No you didnt, no account is taken of the SV signal variation with elevation. ws *** WarrenS wrote: Thanks, Nice set of references as always. OK, so its not 100db, But you may of missed my point yet again. If you think I said that a 10 cent pie pan is a good substitute for a $1000 survey antenna in all applications, I think we all know that would be Nonsense. BUT what may not be known is: that a turned up pie pan under my cheap patch/puck antenna, works about as good as an expensive survey antenna for use with a Tbolt GPSDO, That's not Nonsense, It's a tested fact. Only for your particular location and antenna. Your explanation of why this appears to work well is still nonsense. You have no actual idea of how the antenna response is affected by the presence of the cake tin, nor did you specify what sort of antenna you are using with it. A patch antenna (like your puck) at the bottom of a cake tin that just happens to be a quarter wave deep may not have much gain over the elevation range of interest. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. So I'm not saying there is anything wrong with using a survey antenna on your GPSDO, if you have more money than cents, and you want the last sub ns of performance. But it is not really necessary, there are many many ways to get more bang for the buck, and they would still need to be done first to take advantage of the survey antenna's small improvement when used for a GPSDO. There appears to be a false impression that choke rings remove all Multipath signals. What they do is to remove multipath ground reflected signals from below the antenna, not multipath signals from above it. ws Bruce *** Bruce wrote: Nonsense, a finite ground plane by itself has little effect on waves incident from underneath, unless of course its a resistive ground plane with just the right surface resistivity. A choke ring antenna doesn't have anything like 100db rejection of multipath signals, the rejection varies with SV elevation. http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf http://www.novatel.com/Docum
Re: [time-nuts] TADD enclosure screw sizes...
Thanks John. I picked some screws up at the local hardware store. I see what you mean about the BNC mounting... FYI, I had to bend the vertical nut ears a bit to be able to get the board in, and screwed in. I'm probably going to be operating "open lid" for a while just to see the LED status. Dave On Sat, Mar 13, 2010 at 10:29 AM, John Ackermann N8UR wrote: > Dave, the standoffs are threaded for a 4-40 screw, but I'll tell you a > secret -- if you use the nuts and washers on the BNC connectors, the board > is held very securely without any need for the mounting screws; I've frankly > never bothered with them. > > John > > > ___ 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] Choke Ring Design for L1
Bruce wrote Those plots give little information about the antenna response to variations in SV elevation directly as the signal strength from theSV also varies with elevation. No account is taken of the SV signal variation with elevation. ws) Correct, but a really Silly comment. Of course for that you compare the before and after plots. BUT, In your zeal to find something to criticize no mater how small, you missed an important point again. These plots are examples that show the whole overall signal strength picture, which can be used to set the Elevation mask among MANY other things. ws *> WarrenS wrote: Bruce wrote: Only for your particular location and antenna. You have no actual idea of how the antenna response is affected by the presence of the cake tin, Those plots give little information about the antenna response to variations in SV elevation directly as the signal strength from the SV also varies with elevation. nor did you specify what sort of antenna you are using with it. The latter are all patch antennas which don't work at all well without a ground plane (either an external one or a built in one). Even the thickness of the ground plane makes a difference to the antenna response: http://www.emtalk.com/tut_1.htm http://www.orbanmicrowave.com/The_Basics_Of_Patch_Antennas.pdf http://www.specemc.com/patch.asp http://piers.mit.edu/piersproceedings/download.php?file=cGllcnMyMDA5bW9zY293fDVQNV8xOTI2LnBkZnwwOTAzMTQwODAxMzA= http://ctvr.ie/docs/RF%20Pubs/IEEEVTC_2007_Investigation%20on%20Miniature%20Wideband%20Patch%20Antenna%20.pdf http://140.117.166.1/eehome/ISCOM2005/SubmitPaper/UploadPapers/ISCON05_00100.pdf A patch antenna at the bottom of a cake tin may not have much gain over the elevation range of interest. Your explanation of why this appears to work well is still nonsense. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. That is exactly what I did with the new Lady Heather, You may want to try it for yourself before your unfounded criticizing or look at the attached. No you didnt, no account is taken of the SV signal variation with elevation. ws *** WarrenS wrote: Thanks, Nice set of references as always. OK, so its not 100db, But you may of missed my point yet again. If you think I said that a 10 cent pie pan is a good substitute for a $1000 survey antenna in all applications, I think we all know that would be Nonsense. BUT what may not be known is: that a turned up pie pan under my cheap patch/puck antenna, works about as good as an expensive survey antenna for use with a Tbolt GPSDO, That's not Nonsense, It's a tested fact. Only for your particular location and antenna. Your explanation of why this appears to work well is still nonsense. You have no actual idea of how the antenna response is affected by the presence of the cake tin, nor did you specify what sort of antenna you are using with it. A patch antenna (like your puck) at the bottom of a cake tin that just happens to be a quarter wave deep may not have much gain over the elevation range of interest. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. So I'm not saying there is anything wrong with using a survey antenna on your GPSDO, if you have more money than cents, and you want the last sub ns of performance. But it is not really necessary, there are many many ways to get more bang for the buck, and they would still need to be done first to take advantage of the survey antenna's small improvement when used for a GPSDO. There appears to be a false impression that choke rings remove all Multipath signals. What they do is to remove multipath ground reflected signals from below the antenna, not multipath signals from above it. ws Bruce *** Bruce wrote: Nonsense, a finite ground plane by itself has little effect on waves incident from underneath, unless of course its a resistive ground plane with just the right surface resistivity. A choke ring antenna doesn't have anything like 100db rejection of multipath signals, the rejection varies with SV elevation. http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf http://www.novatel.com/Documents/Papers/3D_choke_ring.pdf http://www.weblab.dlr.de/rbrt/pdf/TN_0505.pdf http://www.leica-geosystems.com/downloads123/zz/nrs/AR25/brochures/AR25_Brochure_en.pdf Bruce *** WarrenS wrote: All true, BUT Just to keep from being mislead, I said what a choke ring antenna does, You have described how it is so good at its job. The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned thingies, around the antenna is to keep reflected Signals from BELOW the antenna from snea
[time-nuts] Choke Ring Pictures
Several years back we had the discussion about choke ring antennas. Dr Thomas Clark - retired NASA - Goddard Space Flight Center - I believe he was head of the VLBI project - made a simple choke ring antenna with an electrical junction box. I made 3 sets using pie plates. I promised somebody the pictures and forgot it until now. The pictures are hosted at http://kc0onr.com/Brian/_MG_0668.jpg http://kc0onr.com/Brian/_MG_0669.jpg I made these units because were I lived was surrounded by mountains 3/4 around my property and I was at 720 feet elevation and the mountains varied from 1000 to 1200 feet. I had a problem that my receivers jumped positions several times and I suspected a multi path problem. I made the first antenna using some RF adsorbent material around the antenna. Helped. After making the choke rings, the problem went away. The other two units were used for carrier phase surveying. With the Motorola Oncore VPZ unit and Waypoint's GrafNav software I could get resolution down to a little under an inch. Brian KD4FM ___ 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] Choke Ring Design for L1
WarrenS wrote: Bruce wrote: Only for your particular location and antenna. severl cheap car type antennas and a pole mounted timing antenna. May not work as well in other locations or with other types of antennas. (Like under the water or with choke antennas) You have no actual idea of how the antenna response is affected by the presence of the cake tin, updates, Take a look at her new antenna plot capability. Those plots give little information about the antenna response to variations in SV elevation directly as the signal strength from the SV also varies with elevation. nor did you specify what sort of antenna you are using with it. The latter are all patch antennas which don't work at all well without a ground plane (either an external one or a built in one). Even the thickness of the ground plane makes a difference to the antenna response: http://www.emtalk.com/tut_1.htm http://www.orbanmicrowave.com/The_Basics_Of_Patch_Antennas.pdf http://www.specemc.com/patch.asp http://piers.mit.edu/piersproceedings/download.php?file=cGllcnMyMDA5bW9zY293fDVQNV8xOTI2LnBkZnwwOTAzMTQwODAxMzA= http://ctvr.ie/docs/RF%20Pubs/IEEEVTC_2007_Investigation%20on%20Miniature%20Wideband%20Patch%20Antenna%20.pdf http://140.117.166.1/eehome/ISCOM2005/SubmitPaper/UploadPapers/ISCON05_00100.pdf A patch antenna at the bottom of a cake tin may not have much gain over the elevation range of interest. gain, cause by making a directly antenna out of it, cause I get some of the same effects with the pie pan turned the other way. Your explanation of why this appears to work well is still nonsense. blocking out multipath reflections of which I have many, and these reflections tend to case dips in the signal level due to cancellations as the sat moves across the sky. Also adds some gain to some antennas. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. That is exactly what I did with the new Lady Heather, You may want to try it for yourself before your unfounded criticizing or look at the attached. No you didnt, no account is taken of the SV signal variation with elevation. ws *** WarrenS wrote: Thanks, Nice set of references as always. OK, so its not 100db, But you may of missed my point yet again. If you think I said that a 10 cent pie pan is a good substitute for a $1000 survey antenna in all applications, I think we all know that would be Nonsense. BUT what may not be known is: that a turned up pie pan under my cheap patch/puck antenna, works about as good as an expensive survey antenna for use with a Tbolt GPSDO, That's not Nonsense, It's a tested fact. Only for your particular location and antenna. Your explanation of why this appears to work well is still nonsense. You have no actual idea of how the antenna response is affected by the presence of the cake tin, nor did you specify what sort of antenna you are using with it. A patch antenna (like your puck) at the bottom of a cake tin that just happens to be a quarter wave deep may not have much gain over the elevation range of interest. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. So I'm not saying there is anything wrong with using a survey antenna on your GPSDO, if you have more money than cents, and you want the last sub ns of performance. But it is not really necessary, there are many many ways to get more bang for the buck, and they would still need to be done first to take advantage of the survey antenna's small improvement when used for a GPSDO. There appears to be a false impression that choke rings remove all Multipath signals. What they do is to remove multipath ground reflected signals from below the antenna, not multipath signals from above it. ws Bruce *** Bruce wrote: Nonsense, a finite ground plane by itself has little effect on waves incident from underneath, unless of course its a resistive ground plane with just the right surface resistivity. A choke ring antenna doesn't have anything like 100db rejection of multipath signals, the rejection varies with SV elevation. http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf http://www.novatel.com/Documents/Papers/3D_choke_ring.pdf http://www.weblab.dlr.de/rbrt/pdf/TN_0505.pdf http://www.leica-geosystems.com/downloads123/zz/nrs/AR25/brochures/AR25_Brochure_en.pdf Bruce *** WarrenS wrote: All true, BUT Just to keep from being mislead, I said what a choke ring antenna does, You have described how it is so good at its job. The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned thingies, around the antenna is to keep reflected Signals from BELOW the antenna from sneaking around int
Re: [time-nuts] Choke Ring Design for L1
WarrenS wrote: Thanks, Nice set of references as always. OK, so its not 100db, But you may of missed my point yet again. If you think I said that a 10 cent pie pan is a good substitute for a $1000 survey antenna in all applications, I think we all know that would be Nonsense. BUT what may not be known is: that a turned up pie pan under my cheap patch/puck antenna, works about as good as an expensive survey antenna for use with a Tbolt GPSDO, That's not Nonsense, It's a tested fact. Only for your particular location and antenna. Your explanation of why this appears to work well is still nonsense. You have no actual idea of how the antenna response is affected by the presence of the cake tin, nor did you specify what sort of antenna you are using with it. A patch antenna (like your puck) at the bottom of a cake tin that just happens to be a quarter wave deep may not have much gain over the elevation range of interest. The variation in antenna response with elevation needs to be measured/calculated before one can safely conclude that such an antenna is universally useful. So I'm not saying there is anything wrong with using a survey antenna on your GPSDO, if you have more money than cents, and you want the last sub ns of performance. But it is not really necessary, there are many many ways to get more bang for the buck, and they would still need to be done first to take advantage of the survey antenna's small improvement when used for a GPSDO. There appears to be a false impression that choke rings remove all Multipath signals. What they do is to remove multipath ground reflected signals from below the antenna, not multipath signals from above it. ws Bruce *** Bruce wrote: Nonsense, a finite ground plane by itself has little effect on waves incident from underneath, unless of course its a resistive ground plane with just the right surface resistivity. A choke ring antenna doesn't have anything like 100db rejection of multipath signals, the rejection varies with SV elevation. http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf http://www.novatel.com/Documents/Papers/3D_choke_ring.pdf http://www.weblab.dlr.de/rbrt/pdf/TN_0505.pdf http://www.leica-geosystems.com/downloads123/zz/nrs/AR25/brochures/AR25_Brochure_en.pdf Bruce *** WarrenS wrote: All true, BUT Just to keep from being mislead, I said what a choke ring antenna does, You have described how it is so good at its job. The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned thingies, around the antenna is to keep reflected Signals from BELOW the antenna from sneaking around into the antenna. It does not effect the signals above the 10 deg or so elevation point. The choke rings are a necessary to get cm type survey accuracy, but a pie pan shield /ground plane pretty much does the same thing at the GPSDO 1ns (1ft) level, where you don't need 100 db rejection for signals below the antenna. What I've found; don't even need to be lucky. Just put an 8 inch pie pan in the right place, facing the right direction. ws *** Hi there, just to prevent from making mistakes ... You can have two different accessories for GNSS antennas: 1) a ground plane it prevents the antenna from receiving signals from beneath the antenna (from the ground, roof or whatever is beneath) ... so this could be your pie pan normally 2) a choke ring it creates an area of high impedance around your antenna; because it is just a (set of) simple quarter wave waveguide(s) with short-circuit on one end, you can build it from a sheet of metal by yourself; you only need to calculate the sizes for your waveguide on the L1 frequency ... and if you are a lucky guy and your pie pan fits these sizes, you probably can use it for that ;-) Best regards Martin Is there a design for a choke ring to add to my existing L1 GPS antenna ? Yeah If you are using it for GPSDO work where a ns is good enough and you don't need cm accuracy, It is called a pie pan with its Lip turned up. A choke rings blocks reflected signals from below the antenna from effecting the signals, a pie pan works pretty good at that also. ws *** Hello The Net: Is there a design for a choke ring to add to my existing L1 GPS antenna ? While there may be some variations to the exact dimensions of a choke ring to a specific type of L1 antenna, either patch, helical, etc., I suspect there is some commonality to the design dimensions. I am looking to start construction and I will be using a cheapie patch/puck antenna. Stan, W1LE ___ 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
Re: [time-nuts] Choke Ring Design for L1
Thanks, Nice set of references as always. OK, so its not 100db, But you may of missed my point yet again. If you think I said that a 10 cent pie pan is a good substitute for a $1000 survey antenna in all applications, I think we all know that would be Nonsense. BUT what may not be known is: that a turned up pie pan under my cheap patch/puck antenna, works about as good as an expensive survey antenna for use with a Tbolt GPSDO, That's not Nonsense, It's a tested fact. So I'm not saying there is anything wrong with using a survey antenna on your GPSDO, if you have more money than cents, and you want the last sub ns of performance. But it is not really necessary, there are many many ways to get more bang for the buck, and they would still need to be done first to take advantage of the survey antenna's small improvement when used for a GPSDO. There appears to be a false impression that choke rings remove all Multipath signals. What they do is to remove multipath ground reflected signals from below the antenna, not multipath signals from above it. ws *** Bruce wrote: Nonsense, a finite ground plane by itself has little effect on waves incident from underneath, unless of course its a resistive ground plane with just the right surface resistivity. A choke ring antenna doesn't have anything like 100db rejection of multipath signals, the rejection varies with SV elevation. http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf http://www.novatel.com/Documents/Papers/3D_choke_ring.pdf http://www.weblab.dlr.de/rbrt/pdf/TN_0505.pdf http://www.leica-geosystems.com/downloads123/zz/nrs/AR25/brochures/AR25_Brochure_en.pdf Bruce *** WarrenS wrote: > > All true, > BUT > Just to keep from being mislead, > I said what a choke ring antenna does, > You have described how it is so good at its job. > > The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned > thingies, around the antenna is to keep reflected Signals from BELOW > the antenna from sneaking around into the antenna. It does not effect > the signals above the 10 deg or so elevation point. > The choke rings are a necessary to get cm type survey accuracy, > but a pie pan shield /ground plane pretty much does the same thing at > the GPSDO 1ns (1ft) level, > where you don't need 100 db rejection for signals below the antenna. > > What I've found; don't even need to be lucky. > Just put an 8 inch pie pan in the right place, facing the right > direction. > > ws > *** > Hi there, > > just to prevent from making mistakes ... > > You can have two different accessories for GNSS antennas: > 1) a ground plane > it prevents the antenna from receiving signals from beneath the > antenna (from the ground, roof or whatever is beneath) > ... so this could be your pie pan normally > 2) a choke ring > it creates an area of high impedance around your antenna; > because it is just a (set of) simple quarter wave waveguide(s) with > short-circuit on one end, you can build it from a sheet of metal by > yourself; you only need to calculate the sizes for your waveguide on > the L1 frequency ... and if you are a lucky guy and your pie pan > fits > these sizes, you probably can use it for that ;-) > > Best regards > > Martin > > >> Is there a design for a choke ring to add to my existing L1 GPS >> antenna ? > > Yeah > If you are using it for GPSDO work where a ns is good enough and you > don't need cm accuracy, > It is called a pie pan with its Lip turned up. > A choke rings blocks reflected signals from below the antenna from > effecting the signals, a pie pan works pretty good at that also. > ws > > *** >> Hello The Net: > >> Is there a design for a choke ring to add to my existing L1 GPS >> antenna ? >> While there may be some variations to the exact dimensions of a choke >> ring to a specific type of L1 antenna, either patch, helical, etc., >> I suspect there is some commonality to the design dimensions. >> I am looking to start construction and I will be using a cheapie >> patch/puck antenna. > > Stan, W1LE > ___ 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] Choke Ring Design for L1
WarrenS wrote: All true, BUT Just to keep from being mislead, I said what a choke ring antenna does, You have described how it is so good at its job. The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned thingies, around the antenna is to keep reflected Signals from BELOW the antenna from sneaking around into the antenna. It does not effect the signals above the 10 deg or so elevation point. The choke rings are a necessary to get cm type survey accuracy, but a pie pan shield /ground plane pretty much does the same thing at the GPSDO 1ns (1ft) level, where you don't need 100 db rejection for signals below the antenna. Nonsense, a finite ground plane by itself has little effect on waves incident from underneath, unless of course its a resistive ground plane with just the right surface resistivity. A choke ring antenna doesnt have anything like 100db rejection of multipath signals, the rejection varies with SV elevation. http://www.javad.com/jns/index.html?/jns/technology/Choke%20Ring%20Theory.html http://www.trimble.com/infrastructure/pdf/gnss-choke-ring-antenna_brochure.pdf http://www.novatel.com/Documents/Papers/3D_choke_ring.pdf http://www.weblab.dlr.de/rbrt/pdf/TN_0505.pdf http://www.leica-geosystems.com/downloads123/zz/nrs/AR25/brochures/AR25_Brochure_en.pdf What I've found; don't even need to be lucky. Just put an 8 inch pie pan in the right place, facing the right direction. ws Bruce *** Hi there, just to prevent from making mistakes ... You can have two different accessories for GNSS antennas: 1) a ground plane it prevents the antenna from receiving signals from beneath the antenna (from the ground, roof or whatever is beneath) ... so this could be your pie pan normally 2) a choke ring it creates an area of high impedance around your antenna; because it is just a (set of) simple quarter wave waveguide(s) with short-circuit on one end, you can build it from a sheet of metal by yourself; you only need to calculate the sizes for your waveguide on the L1 frequency ... and if you are a lucky guy and your pie pan fits these sizes, you probably can use it for that ;-) Best regards Martin Is there a design for a choke ring to add to my existing L1 GPS antenna ? Yeah If you are using it for GPSDO work where a ns is good enough and you don't need cm accuracy, It is called a pie pan with its Lip turned up. A choke rings blocks reflected signals from below the antenna from effecting the signals, a pie pan works pretty good at that also. ws *** Hello The Net: Is there a design for a choke ring to add to my existing L1 GPS antenna ? While there may be some variations to the exact dimensions of a choke ring to a specific type of L1 antenna, either patch, helical, etc., I suspect there is some commonality to the design dimensions. I am looking to start construction and I will be using a cheapie patch/puck antenna. Stan, W1LE ___ 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] Choke Ring Design for L1
For detailed measurements of six different choke ring GPS antennas, see; http://facility.unavco.org/project_support/permanent/equipment/antennas/ant_cals.html John WA4WDL -- From: "WarrenS" Sent: Saturday, March 13, 2010 7:46 PM To: "Discussion of precise time and frequency measurement" Subject: Re: [time-nuts] Choke Ring Design for L1 All true, BUT Just to keep from being mislead, I said what a choke ring antenna does, You have described how it is so good at its job. The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned thingies, around the antenna is to keep reflected Signals from BELOW the antenna from sneaking around into the antenna. It does not effect the signals above the 10 deg or so elevation point. The choke rings are a necessary to get cm type survey accuracy, but a pie pan shield /ground plane pretty much does the same thing at the GPSDO 1ns (1ft) level, where you don't need 100 db rejection for signals below the antenna. What I've found; don't even need to be lucky. Just put an 8 inch pie pan in the right place, facing the right direction. ws *** Hi there, just to prevent from making mistakes ... You can have two different accessories for GNSS antennas: 1) a ground plane it prevents the antenna from receiving signals from beneath the antenna (from the ground, roof or whatever is beneath) ... so this could be your pie pan normally 2) a choke ring it creates an area of high impedance around your antenna; because it is just a (set of) simple quarter wave waveguide(s) with short-circuit on one end, you can build it from a sheet of metal by yourself; you only need to calculate the sizes for your waveguide on the L1 frequency ... and if you are a lucky guy and your pie pan fits these sizes, you probably can use it for that ;-) Best regards Martin Is there a design for a choke ring to add to my existing L1 GPS antenna ? Yeah If you are using it for GPSDO work where a ns is good enough and you don't need cm accuracy, It is called a pie pan with its Lip turned up. A choke rings blocks reflected signals from below the antenna from effecting the signals, a pie pan works pretty good at that also. ws *** Hello The Net: Is there a design for a choke ring to add to my existing L1 GPS antenna ? While there may be some variations to the exact dimensions of a choke ring to a specific type of L1 antenna, either patch, helical, etc., I suspect there is some commonality to the design dimensions. I am looking to start construction and I will be using a cheapie patch/puck antenna. Stan, W1LE ___ 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] Choke Ring Design for L1
All true, BUT Just to keep from being mislead, I said what a choke ring antenna does, You have described how it is so good at its job. The Main purpose of the choke ring's, hi impedance, 1/4 wave, tuned thingies, around the antenna is to keep reflected Signals from BELOW the antenna from sneaking around into the antenna. It does not effect the signals above the 10 deg or so elevation point. The choke rings are a necessary to get cm type survey accuracy, but a pie pan shield /ground plane pretty much does the same thing at the GPSDO 1ns (1ft) level, where you don't need 100 db rejection for signals below the antenna. What I've found; don't even need to be lucky. Just put an 8 inch pie pan in the right place, facing the right direction. ws *** Hi there, just to prevent from making mistakes ... You can have two different accessories for GNSS antennas: 1) a ground plane it prevents the antenna from receiving signals from beneath the antenna (from the ground, roof or whatever is beneath) ... so this could be your pie pan normally 2) a choke ring it creates an area of high impedance around your antenna; because it is just a (set of) simple quarter wave waveguide(s) with short-circuit on one end, you can build it from a sheet of metal by yourself; you only need to calculate the sizes for your waveguide on the L1 frequency ... and if you are a lucky guy and your pie pan fits these sizes, you probably can use it for that ;-) Best regards Martin Is there a design for a choke ring to add to my existing L1 GPS antenna ? Yeah If you are using it for GPSDO work where a ns is good enough and you don't need cm accuracy, It is called a pie pan with its Lip turned up. A choke rings blocks reflected signals from below the antenna from effecting the signals, a pie pan works pretty good at that also. ws *** Hello The Net: Is there a design for a choke ring to add to my existing L1 GPS antenna ? While there may be some variations to the exact dimensions of a choke ring to a specific type of L1 antenna, either patch, helical, etc., I suspect there is some commonality to the design dimensions. I am looking to start construction and I will be using a cheapie patch/puck antenna. Stan, W1LE ___ 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] Choke Ring Design for L1
Hi there, just to prevent from making mistakes ... You can have two different accessories for GNSS antennas: 1) a ground plane it prevents the antenna from receiving signals from beneath the antenna (from the ground, roof or whatever is beneath) ... so this could be your pie pan normaly 2) a choke ring it creates an area of high impedance around your antenna; because it is just a (set of) simple quarter wave waveguide(s) with short-circuit on one end, you can build it from a sheet of metal by yourself; you only need to calculate the sizes for your waveguide on the L1 frequency ... and if you are a lucky guy and your pie pan fits these sizes, you probably can use it for that ;-) Best regards Martin ___ 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] Oscilloquartz 8650S
Fellow members of time-nuts, I have recently acquired an Oscilloquartz 8650S var. 00 5MHz oscillator. Now i am looking for some information about this oscillator, i could find no information about it on the site of Oscilloquartz, so i am hoping that someone on this list has some data for this oscillator so i have an idea what kind of performance i can expect. Sincerely, Stijn Nestra ___ 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] 5370A vs 5370B
Hi Ok, I got enough time to play a bit more with the 5370B today. Here's what I found (all running on the internal standard): If I take the gate time out to 1 second, the frequency display reads as it should. If I look at the standard deviation on various samples of period I get some interesting data: With the instrument cold, I get some amazingly low (like 4 ps) standard deviations on 10K and 100K sample sets. With it cold I get 15-30 ps on 100 and 1K sample sets. Once things heat up I get numbers in the 20-30 ps for all sample sets. I'm guessing that means that nothing's major broke, but I still might find regulator that needs replacement. Bob On Mar 10, 2010, at 7:48 AM, Magnus Danielson wrote: > Bob Camp wrote: >> Hi >> Yes indeed, the period was measured with the two channels in the com mode >> and the reference >> into one of them. I hadn't considered the trigger offset issues and was >> expecting something >> sub-100 ps rather than 500 ps. Obviously I need to spend some "quality time" >> with this beast. >> Now I gotta figure out how to change the gate time :}.. > > If you do not fiddle with trigger levels, you _will_ loose accuracy. It is a > systematic error. > >> It sounds like my oscillator buffer board is going to get butchered pretty >> soon. > > I hope you mean modified. Applying a short at the right point improves the > situation, but you don't need that to get started. It is a refinement that > could wait for a little while. > > Cheers, > Magnus > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ 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] TADD enclosure screw sizes...
Dave, the standoffs are threaded for a 4-40 screw, but I'll tell you a secret -- if you use the nuts and washers on the BNC connectors, the board is held very securely without any need for the mounting screws; I've frankly never bothered with them. John Dave hartzell said the following on 03/13/2010 12:51 PM: Hello, I am placing my TADD-2 into the TAPR TADD enclosure, and I need to know the size / threads of the fixed mounting posts. Anyone know? Thanks, Dave ___ 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] Allan deviation
>Any one of the counters listed above can do this measurement, A decent time nut Allan Deviation needs to have noise floor of below 1e-12. To do this for a 1sec ADEV, it needs a resolution of under 1ps, so NO not all the counters can do that. ws On Mar 13, 2010, at 10:23 AM, Raj wrote: >> From KO4BB page > http://www.ko4bb.com/Timing/FAQ-1.php > > What exactly would we be measuring unless we compare our standards to a > perfect standard ? > > Maybe be a jittery oscillator with a slow drifter on a walkabout. :-) > >> The Allan Deviation is typically computed from a series of Time Interval >> (TI) measurements against a reference oscillator. Any one of the counters >> listed above can do this measurement, which simply is the measure of the >> delay between a signal on Input A (Start channel) and another signal on >> Input B (Stop channel). > > 73 & a great weekend! > > -- > Raj, VU2ZAP > Bangalore, India. ___ 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] Choke Ring Design for L1
>Is there a design for a choke ring to add to my existing L1 GPS antenna ? Yeah If you are using it for GPSDO work where a ns is good enough and you don't need cm accuracy, It is called a pie pan with its Lip turned up. A choke rings blocks reflected signals from below the antenna from effecting the signals, a pie pan works pretty good at that also. ws *** > Hello The Net: > Is there a design for a choke ring to add to my existing L1 GPS antenna ? > While there may be some variations to the exact dimensions of a choke > ring to a specific type of L1 antenna, either patch, helical, etc., > I suspect there is some commonality to the design dimensions. > I am looking to start construction and I will be using a cheapie > patch/puck antenna. Stan, W1LE ___ 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] TADD enclosure screw sizes...
Hello, I am placing my TADD-2 into the TAPR TADD enclosure, and I need to know the size / threads of the fixed mounting posts. Anyone know? Thanks, Dave ___ 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] Thunderbolt antenna?
Good information to know, if one is doing survey work. But some NON-Nut needs to ask, SO WHAT? A 3 foot error may cause + - 3ns of additional phase time error, which is well below the short term GPS noise level. If that is averaged over the 500 or so second TC loop or the 48 hrs supper survey time, it's more like an additional 1e-12 to 1e-15 or so freq noise error per day, which is not a problem for the normal NUT. I've compared that antenna to an cheap INDOOR puck antenna on a properly set up Tbolt and the effects are hardly visible on a supper modified, temperature controlled, double oven, externally controlled Tbolt at the 1e-12 range, So for the extreme nut a great antenna is a Must, but for the more Normal nut, they are not going to see any difference. And then there is the non explained point that what causes the most antenna reported time error of the typical overhead satellite is not position error but elevation errors, and the reported height seem to vary by 10 + times what the Lat/Lon does and yet does not have nearly as much effect on the GPSDO. And back to the original question, What I have found is that my $20.00 GPS antenna which looks to be the same as eBay Item number: 390147799311 WITH A PROPER PIE PAN mounted UNDER IT, works Almost as good as the $1000 unit (within a 1 ns) on my Tbolt. Or if you want to save even more money and can stand an addition couple ns of phase noise, just put your cheap puck antenna on a pie pan and place that on the roof with a clear view down to 30 deg. Using the latest Lady Heather signal level plot to see what your antenna's clear view is can help a lot ws * Mark Said: All the choke ring antennas were similar in performance. The Aero/Leica one is optimized for the L1 freq only. All the other choke rings that I tested did L1/L2 which compromises performance a bit which did show up in the data (but at a level that could just have been random luck of the draw). Where the L1 only antenna was getting precision survey offsets in the one inch area, the L1/L2 units were in the 2-3 inch area. Lesser survey grade antennas might be in the 6-12 inch range. Conical timing antennas in the 1-2 foot range (they are just a higher quality patch antenna under a conical radome). Cheap automotive patch antennas in the 3+ foot range. ** Hello, I'm looking for a decent outdoor antenna for my Thunderbolt... I need to graduate beyond the puck-antenna in the window sill. Any recommendations and/or sources (the lower cost, the better of course!)? Thanks, Dave ___ 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] What FreeBSD version for Soekris net4501 NTP server?
Hi A lot depends on just how bleeding edge you happen to want to be. Both 8.0 and 7.2 run ok on the 4501. Bob On Mar 13, 2010, at 10:59 AM, Pieter ten Pierick wrote: > Hello, > > Do people on the list have a preference for using a specific version of > FreeBSD > for a ntpd/ntpns server running on a Soekris net4501 board? > > I finally ordered (and promptly received) the Soekris net4501 board that I > wanted to connect to my Thunderbolt. > Having to start fresh (not having a FreeBSD machine...) I can choose any > version... > Any reasons not to use the latest (bleeding edge) version? > All 'How To Soekris & ntp' info on the internet are for older versions of > FreeBSD, > but those pages are then also from way back... > > Thanks, > Pieter. > > > ___ > 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] Allan deviation
Hi One real world application is or an autonomous box is supplied with many clock signals., The task is to select the one that's best. The standard of comparison may be far from "perfect" in this case. Bob On Mar 13, 2010, at 10:23 AM, Raj wrote: >> From KO4BB page > http://www.ko4bb.com/Timing/FAQ-1.php > > What exactly would we be measuring unless we compare our standards to a > perfect standard ? > > Maybe be a jittery oscillator with a slow drifter on a walkabout. :-) > >> The Allan Deviation is typically computed from a series of Time Interval >> (TI) measurements against a reference oscillator. Any one of the counters >> listed above can do this measurement, which simply is the measure of the >> delay between a signal on Input A (Start channel) and another signal on >> Input B (Stop channel). > > 73 & a great weekend! > > -- > Raj, VU2ZAP > Bangalore, India. > ___ > 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] Choke Ring Design for L1
Hi Stan, > Hello The Net: > > Is there a design for a choke ring to add to my existing L1 GPS antenna ? > > While there may be some variations to the exact dimensions of a choke > ring to a specific > type of L1 antenna, either patch, helical, etc., > I suspect there is some commonality to the design dimensions. > > I am looking to start construction and I will be using a cheapie > patch/puck antenna. > > Stan, W1LE Here might be a good start for you. http://www.febo.com/pipermail/time-nuts/2008-January/029277.html -- Björn ___ 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] Choke Ring Design for L1
Hello The Net: Is there a design for a choke ring to add to my existing L1 GPS antenna ? While there may be some variations to the exact dimensions of a choke ring to a specific type of L1 antenna, either patch, helical, etc., I suspect there is some commonality to the design dimensions. I am looking to start construction and I will be using a cheapie patch/puck antenna. Stan, W1LE ___ 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] What FreeBSD version for Soekris net4501 NTP server?
In message <9b81a82e-b5a5-45ba-a36d-c2f6e4fb0...@tenpierick.com>, Pieter ten Pi erick writes: >Hello, > >Do people on the list have a preference for using a specific version >of FreeBSD >for a ntpd/ntpns server running on a Soekris net4501 board? Any recent version will do. I would take a 7.x or 8.x version at this point. -- 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.
[time-nuts] Thunderbolt antenna?
All the choke ring antennas were similar in performance. The Aero/Leica one is optimized for the L1 freq only. All the other choke rings that I tested did L1/L2 which compromises performance a bit which did show up in the data (but at a level that could just have been random luck of the draw). Where the L1 only antenna was getting precision survey offsets in the one inch area, the L1/L2 units were in the 2-3 inch area. Lesser survey grade antennas might be in the 6-12 inch range. Conical timing antennas in the 1-2 foot range (they are just a higher quality patch antenna under a conical radome). Cheap automotive patch antennas in the 3+ foot range. _ Hotmail is redefining busy with tools for the New Busy. Get more from your inbox. http://www.windowslive.com/campaign/thenewbusy?ocid=PID27925::T:WLMTAGL:ON:WL:en-US:WM_HMP:032010_2 ___ 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] What FreeBSD version for Soekris net4501 NTP server?
Hello, Do people on the list have a preference for using a specific version of FreeBSD for a ntpd/ntpns server running on a Soekris net4501 board? I finally ordered (and promptly received) the Soekris net4501 board that I wanted to connect to my Thunderbolt. Having to start fresh (not having a FreeBSD machine...) I can choose any version... Any reasons not to use the latest (bleeding edge) version? All 'How To Soekris & ntp' info on the internet are for older versions of FreeBSD, but those pages are then also from way back... Thanks, Pieter. ___ 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] Allan deviation
>From KO4BB page http://www.ko4bb.com/Timing/FAQ-1.php What exactly would we be measuring unless we compare our standards to a perfect standard ? Maybe be a jittery oscillator with a slow drifter on a walkabout. :-) >The Allan Deviation is typically computed from a series of Time Interval (TI) >measurements against a reference oscillator. Any one of the counters listed >above can do this measurement, which simply is the measure of the delay >between a signal on Input A (Start channel) and another signal on Input B >(Stop channel). 73 & a great weekend! -- Raj, VU2ZAP Bangalore, India. ___ 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] DMTD Systems Papers
Hi Depending on just what sort of DMTD you are after, there are an enormous number of JPL reports on their system. They range from papers that are basically operating manuals (when this happens that shows up on the screen) to deep dives on obscure math. If you are not after a 100 Hz system they may be of limited use. If you are getting into building one, things like the Collins paper on hard limiters would be of use. Bob On Mar 13, 2010, at 1:06 AM, Brian Kirby wrote: > Here's a list of papers I have found on DMTD system designs > that have some inside details. If you know of others, please > add for future reference. Brian - KD4FM > > Papers on Dual-Mixer Time-Difference systems: > > Some Aspects of the Theory and Measurement of Frequency > Fluctuations in Frequency Standards. Leonard S. Cutler > (Hewlett-Packard Co.) (HP) and Campbell L. Searle > (Massachusetts Institute of Technology) (MIT). 1966. Concept. > > Accurate Measurements of Spectra Density of Phase Noise in > Devices. F. L. Walls, S. R. Stein. NBS/NIST. Mixer > Information. > > The Measurement of Frequency and Frequency Stability > of Precision Oscillators. David W. Allan National Bureau > of Standards (NBS), now the National Institute of Standards > and Technology (NIST). NBS Technical Note 669. > > Report on NBS Dual Mixer Time Difference System (DMTD) built > for time-domain measurements associated with Phase 1 of GPS. David Allan > NBS/NIST. Has complete schematics of unit > described. NBSIR 75-827. > > An NBS Phase Noise Measurement System Built for Frequency > Domain measurements.S. R. Stein NIST. NBSIR 76-846. Phase Noise test > set for GPS, includes schematics. > > Picosecond Time Difference Measurement System. D. W. Allan, > H. Daams. 1975.29th Annual Symposium Frequency Control. Basic schematics. > > Extending the Range and Accuracy of Phase Noise Measurements. F. L. Walls, A. > J. D. Clements, C. M. Felton, M. A. Lombardi, > and M. D. Vanek. NIST. 1988. Phase noise systems, a little > about mixer terminations. > > Environmental Effects in Mixers and Frequency Distribution > systems. L. M. Nelson and F. L. Walls NIST. 1992 IEEE > Frequency Control Symposium. Cable timing errors and mixer > terminations. > > The Effect of Harmonic Distortion on Phase errors in Frequency > Distribution and Synthesis. F. L. Walls, F. G. Ascarrunz. NIST, > SpectraDynamics. Power effects on mixers. > > Design Considerations in State-of-the-art Signal Processing > and Phase Noise Measurement systems. F. L. Walls, S. R. Stein, > James E. Gray, David J. Glaze, NIST. Isolation amps and > mixer terminations. > > Application Note 283-3 Low Phase Noise Applications of the > HP 8662A and 8663A Synthesized Signal Generators. Hewlett-Packard Co.. Goes > into Phase Noise designs and has > general purpose information. > > 10514A/B Mixers Operating and Service Manual 02298-3 Jan 1967, 10534A/B > Mixers Operating and Service Manual 02396-2 June 1968. Hewlett-Packard Co. > (1) Frequently asked questions about phase detectors. Mini-Circuits > AN-41-001. (2) Most often asked questions about > mixers. (3) Most Often Asked Questions - Phase detectors. > (1) Mixer Application Information. (2) Mixers: Part 1. Characteristics and > Performance. (3) Mixers: Part 2 Theory and > Technology. (4) Mixers as Phase Detectors. Watkins-Johnson > Company Tech-notes. > > Application Note - Double Balance Mixers. Adams-Russell. > > (1) Phase Noise (2005). (2) Tutorial on the double balanced > mixer (2006). (3) Experimental methods for the measurement > of phase noise and frequency stability (2007). (4) Short > course on stable oscillators (2009). Enrico Rubiola. FEMTO-ST Institute. > Optimization of Dual-Mixer Time Difference Multiplier. L. Sojdr, J. Cermak, > R. Barillet. Czech Academy of Sciences, > BNM-SYRTE Observatoire de Paris. Describes a DMTD system. > > Dual-Mixer Time-Difference Multiplier. A. Kuna, J. Roztocil. Czech Technical > University. Improvements on DMTD system. > > > > > > > > ___ > 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] Change of email address
I'm in the middle of switching email addresses. Old email: david.partri...@dsl.pipex.com New email: david.partri...@perdrix.co.uk Mail to either address will get through, but the new email address is preferred. I'm still sending as the old email address for now, but will change over soon. My website (such as it is) is now www.perdrix.co.uk - more stuff will be added RSN (honest). Regards, David Partridge Email:david.partri...@perdrix.co.uk ___ 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] Frequency divider board PCBs
I'm considering getting another batch of PCBs made up for the frequency divider design I sold a number of the other year. The basic target is low jitter, 10MHz sine in, square wave outputs at 10MHz, 5MHz, 1MHz, and one other output that is switchable from 100kHz down to 1Hz. These are four layer boards, 5" by 3.5", and likely cost (based on a qty of 20) is about GBP20 each for the board with shipping extra. Note that the design uses mostly surface mount parts. I can't afford a speculative order as I'm not in work. So I'm asking for offline emails indicating "intent to purchase" to determine if this can fly. Obviously if there's enough interest I can order a larger quantity of boards which will bring the price down. Schematic on request (uses 74AC and 74HC logic), not a micro, CPLD, or FPGA in site. The new boards will have revisions so that no EC wires will be necessary. Regards, David Partridge ___ 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] Thunderbolt antenna?
That's a dramatic and impressive difference Mark! Were the other choke-rings similarly better than the "ordinary" conical, or was this one heads and shoulders better than the rest? I was just wondering if it was the choke-ring concept that gave the major improvement, with this one just being slightly better executed? Regards, Peter Vince (London, England) On 13 March 2010 02:52, Mark Sims wrote: > > Yep, it's a standard choke ring antenna. It's optimized for L1 freqs. > Leica also rebranded and sold it. > > I have tested 6 different choke ring and geodetic grade antennas. This one > works the best of the bunch (at least for me). With my 48 hour precision > survey code, I got results within an inch or so of the true location. VERY > impressive. Most of the other geodetic quality antennas were in the 4-6 inch > range. > > Attached are two plots of the fixes produced by each antenna. The first is a > Symmeticom conical timing antenna. The other is the choke ring antenna. > ___ 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.
