Re: [time-nuts] LHCP patch antenna
On 01/23/2013 07:08 AM, Jim Lux wrote: On 1/22/13 9:08 AM, Joe Leikhim wrote: John; You might look into building your own, _scaling up_ from a G3RUH design (2.4 GHz) note that they were illuminating a 60 cm dish in those experiments, that's not a very big reflector for 12.5 cm wavelength at 2.4 GHz. not even 5 lambda. I'm not sure you can really model that system by physical optics. the OP wants to illuminate 120 cm for 1.5GHz, 20 cm lambda.. that's 6 lambda. Still a pretty small dish, wavelength wise. Both will have issues with diffraction around the edges, so if you're worried about noise temperature, you'd want to seriously under illuminate. First degree surpression of reflexes will also be lost, it will be the antenna gain that get some additional benefit, but the offset would have been better for a larger dish. 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.
Re: [time-nuts] One Kg Quartz Resonator
On 01/23/2013 02:32 AM, Mike S wrote: On 1/22/2013 3:30 PM, Bruce Griffiths wrote: But can the number and type of atoms in such a standard be counted? Otherwise its not a primary standard. Can you have a Cs under zero acceleration and at zero temperature, the only conditions for which the second is defined? Since most metric units are derived from the definition of the second, are any primary standards, in your opinion? Isn't it defined for zero sea-level, that is standard acceleration? Besides, as you put two standards in the same lab at the same level, they should give the same values. Some of the art is to compensate for various effects, so accurately model, estimate and compensate goes into the tricks of trade today. The standard shifts as better methods of realizing them occurs, the kg has been taking a long time to shift from the original lump of metal. 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.
Re: [time-nuts] Better gps antennas than a Symmetricom 58532A
mspencer12...@yahoo.ca said: This URL goes into some of the issues involved in using 75 ohm coax in a gps system. I do acknowledge that several GPS manufacturers have promoted the use of 75 ohm coax so some of the conclusions might be arguable.. If the coax is short, the loss due to mismatch dominates. If the coax is long, the attenuation per X meters will dominate. There should be a crossover length What is it for 50 ohm RG-58 and 75 ohm RG-6? If you are designing your own antenna, you have the option of making one that matches 75 ohm rather than 50. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] One Kg Quartz Resonator
Isn't it defined for zero sea-level, that is standard acceleration? How do you define sea level? Daniel Kleppner's Time Too Good to Be True in Physics Today, March 2006 pointed out that the time-geeks will soon own the definition of sea level. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] One Kg Quartz Resonator
Isn't it defined for zero sea-level, that is standard acceleration? How do you define sea level? http://en.wikipedia.org/wiki/EGM96 http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm2008/egm08_wgs84.html Daniel Kleppner's Time Too Good to Be True in Physics Today, March 2006 pointed out that the time-geeks will soon own the definition of sea level. You need to use a lot of time-geek-tools to have a working GPS or VLBI system. /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.
Re: [time-nuts] One Kg Quartz Resonator
Hi As with the one kg resonator, you need to mount the bar *somehow*. The idea is generally to suspend the resonator at a point that least affects the resonance (a dead spot). With a large bar, making it manually adjustable is practical. Not so much with a smaller part. Bob Il 2013-01-23 01:54 jmfranke ha scritto: I also have two of the crystals. The discs are used to adjust the phase of the acoustic feedback to the resonator ends. John WA4WDL Thanks Bob and John, I gave a superficial read to one of the patents, as I understand the patent says that the plates are there to give predictable acoustic reflections (yes I know I should read before posting questions :) ) Bob the dead spot mounting is interesting (are they called nodal points, or I'm mistaking terminology?). The metallization on the 50kc rod is on top and bottom plates, while the 100kc is swapped, one electrode on top on one half and bottom on the other half rod. The suspension is also different, the 50kc is supended in the middle while the 100kc is suspended in two points. How are supposed to vibrate these bars? Will they inflect along the long axis? Or elongate? Or a mix of different motions? Thanks. Fabio. ___ 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] One Kg Quartz Resonator
Hi You want to mount the crystal at a point that is not moving (much) while the crystal is in resonance. For a normal AT, that's out at the edge. For most bar cuts, yes you mount it at a node. Without knowing the mode that the bar is resonating in, it's a bit hard to guess where the nodes will be. Just looking at the bar, you wouldn't *guess* that the end points would be nodes... Bob On Jan 23, 2013, at 5:07 AM, Fabio Eboli fabi...@quipo.it wrote: Hi As with the one kg resonator, you need to mount the bar *somehow*. The idea is generally to suspend the resonator at a point that least affects the resonance (a dead spot). With a large bar, making it manually adjustable is practical. Not so much with a smaller part. Bob Il 2013-01-23 01:54 jmfranke ha scritto: I also have two of the crystals. The discs are used to adjust the phase of the acoustic feedback to the resonator ends. John WA4WDL Thanks Bob and John, I gave a superficial read to one of the patents, as I understand the patent says that the plates are there to give predictable acoustic reflections (yes I know I should read before posting questions :) ) Bob the dead spot mounting is interesting (are they called nodal points, or I'm mistaking terminology?). The metallization on the 50kc rod is on top and bottom plates, while the 100kc is swapped, one electrode on top on one half and bottom on the other half rod. The suspension is also different, the 50kc is supended in the middle while the 100kc is suspended in two points. How are supposed to vibrate these bars? Will they inflect along the long axis? Or elongate? Or a mix of different motions? Thanks. Fabio. ___ 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] Racal MA-259 Crystal frequency standard on UK eBay
http://cgi.ebay.co.uk/230912316345 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] Better gps antennas than a Symmetricom 58532A
On 1/23/13 12:41 AM, Hal Murray wrote: mspencer12...@yahoo.ca said: This URL goes into some of the issues involved in using 75 ohm coax in a gps system. I do acknowledge that several GPS manufacturers have promoted the use of 75 ohm coax so some of the conclusions might be arguable.. If the coax is short, the loss due to mismatch dominates. If the coax is long, the attenuation per X meters will dominate. And it's not clear that there's actually loss due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR. The usual spec for the antenna is 1.5:1, so for all you know the Antenna and Receiver is already 75 ohms, and RG6 will give you a better match than 50 ohm LMR400. probably a bigger issue *might* be that reflections will create synthetic multipath from the signal reflecting back and forth in the cable. There should be a crossover length What is it for 50 ohm RG-58 and 75 ohm RG-6? If you are designing your own antenna, you have the option of making one that matches 75 ohm rather than 50. ___ 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] Racal MA-259 Crystal frequency standard on UK eBay
Very tempting but its a local pickup only. On Wed, Jan 23, 2013 at 8:41 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: http://cgi.ebay.co.uk/230912316345 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] How far can I push a crystal?
Hi Ed, Thanks, your explanation of single PLL helps. I see it now somewhat in the sense of only have to BUILD a single PLL to make things work. I can appreciate the simplified effort greatly. I also now think of the PLO as an oscillator locked to a tuned harmonic that (probably) comes from some sort of comb generator, so that's not a PLL in the more conventional sense, and the resulting system becomes a true single PLL design. I'll look forward to hearing how it works out. Bob L. - Original Message From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Tue, January 22, 2013 11:46:35 PM Subject: Re: [time-nuts] How far can I push a crystal? I tried to send this message on Sunday, but for some reason it didn't go through, so here it is again. Please excuse any redundancy if the original shows up. I will have an update of the project soon. Hi Bob L., Your suggestion of the 300/953 scheme was inspiration for what hopefully will be the simplest solution of all - I've started building it. First, I should clarify more, that the original scheme actually has three phase-locked loops - a 10.7 MHz, a 10.0594 MHz, and the final one, 1207.133 MHz. The last one is a PLO brick that just multiplies any RF input by any n within reason to phase lock the microwave output (to nth harmonic of input). I wasn't counting that one, since it's more or less a fixed function, but it's a variable (arbitrary n) in the numbers game. So, when I was referring to getting rid of one PLL, I meant not needing to produce the intermediate 10.7 MHz, since the 953 gives a rational number solution directly from 1 or 10 MHz - this is the single PLL scenario. I tested the PLO and microwave section with 15.88333 MHz = (10 MHz/600)*953 from a synthesizer, and it worked just fine. The PLO is tuned near 1207 MHz, and uses whatever n lands it within lock range, so n=76 in this case. If you adjust the cavity, n can just as easily be 75 or 77, with different output frequencies, or a number of numbers that satisfy the bounds of operation. So, the trick is to produce that one correct frequency from the 10 MHz reference, cleanly enough to get the job done, and feed it to the PLO - the n value takes care of itself. The way it's partitioned now, I will have one can containing the 15.883 MHz VCXO (74HC86 and a 16 MHz ceramic resonator), two LAN LPFs, a 74HC4020 feedback divider (1/953), and a CD4046B PLL. A second can, which is needed anyway for handling the various external and internal 10 and 1 MHz references, will not only route and scale, but will also include the divider to make the 16.6 kHz (10 MHz/600) reference for the other box. So, the overall synthesis chain is (10 MHz/600)*953*76=1207.13 MHz. Pretty simple. Ed ___ 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] Is there any way to use a TIC to measure time of reflection on a PCB?
There's a fairly interesting (to me at least), discussion on an Agilent forum devoted to the calibration of vector network analyzers. http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809tstart=0 The title of the thread is Coefficients of fringing capacitance polynomial A student needs to find the open-circuit fringing capacitance of a piece of microstrip line. For this he needs to know the time between the reference plane of the SMA connector and the open circuit microstrip. An obvious way to do this is with a vector network analyzer with a time-domain option. In HP/Agilent VNAs, this is option 010. The student has access to an obsolete and unsuported HP 8753C 6 GHz VNA, but it does not have the time-domain option. I thought he might be able to convince someone at Agilent to give the uni this option, which is just enabled by software. So far that has not worked. I did offer to help with access to my HP 8720D VNA which has the time-domain option. But more to the point, one of Agilent's VNA gurus, Dr. Joel Dunsmore, the author of this book http://www.amazon.co.uk/Handbook-Microwave-Component-Measurements-Techniques/dp/1119979552 has said the time domain resolution would not be sufficent on a 6 GHz VNA for this - he would need a resolution of around 100 ps, which would need a 20 GHz VNA. My HP 8720D VNA is a 20 GHz model, but I don't have a calibration kit for greater than 9 GHz. I was just wondering if there was any way a time-interval counter could help.I can't think of a way, and I'm 95% sure there is not a way, but a TIC would offer the timing resolution better than is achievable with a 6 GHz VNA. I suspect one would need a directional coupler to look at the reflected wave, and there is no way to correct for systematic errors like there is with a VNA. If I had an HP or Agilent 85052B Standard Mechanical Calibration Kit, (DC to 26.5), then my VNA would just about have enough time-domain resolution, but I don't have such a cal kit, and they are not exactly cheap, even on eBay. 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] Better gps antennas than a Symmetricom 58532A
snip And it's not clear that there's actually loss due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR. The usual spec for the antenna is 1.5:1, so for all you know the Antenna and Receiver is already 75 ohms, and RG6 will give you a better match than 50 ohm LMR400. snip An excellent point. A similar issue is the connectors. If you read the data sheets for many common connectors and adapters you'll find that a lot of them are only rated for a 1.2:1 VSWR. I ran into this issue a few years ago when trying to measure reflection coefficient in a system using TNC connectors. It turned out that the connectors set the VSWR limit, not the test of the measuring system. -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] Is there any way to use a TIC to measure time of reflection on a PCB?
On 1/23/13 6:48 AM, David Kirkby wrote: There's a fairly interesting (to me at least), discussion on an Agilent forum devoted to the calibration of vector network analyzers. http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809tstart=0 The title of the thread is Coefficients of fringing capacitance polynomial A student needs to find the open-circuit fringing capacitance of a piece of microstrip line. For this he needs to know the time between the reference plane of the SMA connector and the open circuit microstrip. Can he build multiple microstrips with known distances, and measure them all and solve for it that way? An obvious way to do this is with a vector network analyzer with a time-domain option. In HP/Agilent VNAs, this is option 010. The student has access to an obsolete and unsuported HP 8753C 6 GHz VNA, but it does not have the time-domain option. Does it have the measurement plane offset option? I'm not in front of my old analyzer in the lab (8720C.. no disk drive), and it does have the transform option, but I'm not sure you need that option to have the dial an offset in the calibration. I've used that to move the reference plane from the connectors at the edge of a board to the device on the board: testing a vector modulator with the display in polar coordinate mode, for instance.. you keep turning the knob til the display is a dot, not a circle or arc. I thought he might be able to convince someone at Agilent to give the uni this option, which is just enabled by software. So far that has not worked. I did offer to help with access to my HP 8720D VNA which has the time-domain option. What measurement uncertainty is called for here? Can you make your own limited purpose cal kit? The open is the challenge. Shorts, loads, and thrus are fairly straightforward. Maybe you have to collect the uncalibrated data with the cal standards and do the cal in post processing in Matlab or something. ___ 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] Better gps antennas than a Symmetricom 58532A
Fat fingers. Replace test with rest. snip And it's not clear that there's actually loss due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR. The usual spec for the antenna is 1.5:1, so for all you know the Antenna and Receiver is already 75 ohms, and RG6 will give you a better match than 50 ohm LMR400. snip An excellent point. A similar issue is the connectors. If you read the data sheets for many common connectors and adapters you'll find that a lot of them are only rated for a 1.2:1 VSWR. I ran into this issue a few years ago when trying to measure reflection coefficient in a system using TNC connectors. It turned out that the connectors set the VSWR limit, not the test of the measuring system. -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. ___ 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] Better gps antennas than a Symmetricom 58532A
For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, you know exactly the application. The loading could effect the antenna pattern if it were not for the preamp. -Original Message- From: Jim Lux jim...@earthlink.net Sender: time-nuts-boun...@febo.com Date: Wed, 23 Jan 2013 06:07:49 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Better gps antennas than a Symmetricom 58532A On 1/23/13 12:41 AM, Hal Murray wrote: mspencer12...@yahoo.ca said: This URL goes into some of the issues involved in using 75 ohm coax in a gps system. I do acknowledge that several GPS manufacturers have promoted the use of 75 ohm coax so some of the conclusions might be arguable.. If the coax is short, the loss due to mismatch dominates. If the coax is long, the attenuation per X meters will dominate. And it's not clear that there's actually loss due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR. The usual spec for the antenna is 1.5:1, so for all you know the Antenna and Receiver is already 75 ohms, and RG6 will give you a better match than 50 ohm LMR400. probably a bigger issue *might* be that reflections will create synthetic multipath from the signal reflecting back and forth in the cable. There should be a crossover length What is it for 50 ohm RG-58 and 75 ohm RG-6? If you are designing your own antenna, you have the option of making one that matches 75 ohm rather than 50. ___ 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] Thunderbolt Monitor
I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ 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] Racal MA-259 Crystal frequency standard on UK eBay
Agreed, and about 30 miles from where I live. However, do I really need one? :-) Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: 23 January 2013 14:18 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Racal MA-259 Crystal frequency standard on UK eBay Very tempting but its a local pickup only. On Wed, Jan 23, 2013 at 8:41 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: http://cgi.ebay.co.uk/230912316345 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. ___ 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 Monitor
I can't help you with the outboard monitor, but I can help with the haywire / mouse situation. Windows thinks that the serial port has a mouse connected because of the 1 / second transmissions from the T-Bolt. At boot time Win looks for serial mice and it gets fooled by seeing something active on that COM port. There was an answer about this issue from Nov. 1, 2010. == NOTE: If you boot Windows with your ThunderBolt connected to the Com port, Windows will think it is a serial mouse and grab the port. It can lead to some interesting Windows behavior as the T-Bolt outputs data. Mike - AA8K Easy fix. Add the following to your Boot.ini file. Obviously, the x stands for the COM port you are using. NoSerialMice:COMx Joe Gray W5JG == This didn't always work for me. Another way to get it to stop using the mouse is to boot, let it find the mouse, and then disable it in the Device Manager. After opening Device Manager you'll find a mouse that doesn't belong there connected to whatever COM port your serial adapter was assigned. If you move the adapter to a different USB port you'll need to do the process again. -John -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Major L. McGee III Sent: Wednesday, January 23, 2013 10:32 AM To: time-nuts@febo.com Subject: [time-nuts] Thunderbolt Monitor I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ 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] Thunderbolt Monitor
I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Better gps antennas than a Symmetricom 58532A
The Thunderbolt book suggests using RG6 (75 ohm) up to some given length and then other cable like RG8if the length is longer. I can't look it up right now. They claim the rg6 is very good because of the double shield. Trimble claims the 75 v. 50 mismatch is trivial. On Wed, Jan 23, 2013 at 12:41 AM, Hal Murray hmur...@megapathdsl.net wrote: mspencer12...@yahoo.ca said: This URL goes into some of the issues involved in using 75 ohm coax in a gps system. I do acknowledge that several GPS manufacturers have promoted the use of 75 ohm coax so some of the conclusions might be arguable.. If the coax is short, the loss due to mismatch dominates. If the coax is long, the attenuation per X meters will dominate. There should be a crossover length What is it for 50 ohm RG-58 and 75 ohm RG-6? If you are designing your own antenna, you have the option of making one that matches 75 ohm rather than 50. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Monitor
John and Ken that did the trick. I ended up trying the easiest option first since I already had device manager up and it worked like a charm. I'll look into Arduino for some options for the lcd project. I keep my Thunderbolt right beside my frequency counter and leave both of them on all the time attached to a good UPS. The counter has a Rubidium oscillator in it but I use the output from the thunderbolt at times as well. My master plan is to build a box for the rack with a low phase noise multi channel distribution amplifier to feed to my other equipment with the 10MHz signal. How my racks are setup the LCD should give me all the info I need in most cases. Sometimes the lady heather software is just too much info. I do like the satellite tracking though. That is a cool feature. Thanks, Major ___ 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 Monitor
Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect you would get about 5% of it into a MSP430. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 11:44 AM To: Major L. McGee III; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Racal MA-259 Crystal frequency standard on UK eBay
Well its some sort of a knock off of the sulzer oscillators. I have two and they are very good. Low noise stable maybe not in a time-nuttery sense but considering they were 1960ish pretty darn good. If shipping were not an issue and within the next few hours the price does not go up several dozens of X I would bid it for the fun of it. By the way the seller may not understand 8 nuts holds everything together. So it is indeed very shippable. He may simply not want the effort. Regards Paul WB8TSL On Wed, Jan 23, 2013 at 11:57 AM, Rob Kimberley robkimber...@btinternet.com wrote: Agreed, and about 30 miles from where I live. However, do I really need one? :-) Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: 23 January 2013 14:18 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Racal MA-259 Crystal frequency standard on UK eBay Very tempting but its a local pickup only. On Wed, Jan 23, 2013 at 8:41 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: http://cgi.ebay.co.uk/230912316345 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. ___ 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] Thunderbolt Monitor
What about Didier's original design?.. _http://ko4bb.com/Timing/GPSMonitor/_ (http://ko4bb.com/Timing/GPSMonitor/) Regards Nigel GM8PZR In a message dated 23/01/2013 16:32:36 GMT Standard Time, maj...@sc.rr.com writes: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ 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] Least costly 10 MHz reference solution
Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places (10 ppb?), so anything that is good to a few ppb is certainly adequate for what I am looking for. I have a OCXO unit that is voltage adjustable - for example, adjusting this to 10.000 MHz per my HP 5334A requires -12.71V. So the simple (maybe) question is, should I go for a Rubidium disciplined unit, or go with a home-brew GPSDO solution using the Vectron OCXO I already have? My main cause of confusion is ignorance concerning all the GPS solutions out there with 1pps outputs, to use in a GPSDO, and which ones jitter too much to be useful (solutions under $50 exist). Thanks in advance. Russ K0WFS ___ 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 Monitor
Chris Albertson wrote: The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I don't have a way to play with it right now, but in the single-user case, is LH Server.exe equivalent to a simple IP console server? If so, I think the low-hanging fruit would be to drop an old Lantronix serial port server into the rack, and just use your existing lan/wifi to run the client on your laptop or whatever. No custom anything. -Nate- ___ 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] Better gps antennas than a Symmetricom 58532A
On 01/23/2013 03:59 PM, John Lofgren wrote: snip And it's not clear that there's actually loss due to mismatch. Most antennas/preamps/receivers don't have exactly 50 ohm impedances. 75/50 is only 1.5:1, and there's an awful lot of antennas and receivers out there that only claim 2:1 VSWR. The usual spec for the antenna is 1.5:1, so for all you know the Antenna and Receiver is already 75 ohms, and RG6 will give you a better match than 50 ohm LMR400. snip An excellent point. A similar issue is the connectors. If you read the data sheets for many common connectors and adapters you'll find that a lot of them are only rated for a 1.2:1 VSWR. I ran into this issue a few years ago when trying to measure reflection coefficient in a system using TNC connectors. It turned out that the connectors set the VSWR limit, not the test of the measuring system. Should I make it a habbit of TDRing my GPS antennas, receivers and splitters? 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.
Re: [time-nuts] Better gps antennas than a Symmetricom 58532A
Just a few comments on the cable and VSWR business. The short version is that unless the run is longer than 100 Ft any antenna with a preamp gain of more than 30 dB will probably do and the VSWR business does not matter at all unless it is truly terrible. For example the loss due to mismatch for various VSWRS is as follows VSWR Mismatch Loss 1.5 0.2 dB 2.0 0.5 dB 3.0 1.2 dB 4.0 1.9 dB Source Microwave Engineer's Handbook 1968 Cable Loss is a consideration for long runs. All data at 1.5 GHz. Cable Loss / 100 Ft RG-614 dB RG-8/RG313 5.8 dB Andrew Cable - Superflex Heliax 1/4 inch Heliax 7.47 dB 3/8 inch Heliax 5.12 dB Sources - Andrew Catalog, ITT Reference Data for Radio Engineers Now you have to consider the effect on the VSWR at one end of the cable at the other end. Here we define Return Loss as the round trip loss of the cable if the far end is SHORTED. That is an infinite VSWR with 100% reflected power. This is Twice the 1 - way loss. Return loss is just another expression for VSWR and one can be converted to the other - Thus Return Loss Equivalent VSWR at input 28 dB (RG-6 shorted) 1.05 to 1 14.4 dB(1/4 Heliax shorted) 1.5 to 1 11.6 dB (RG-213 shorted) 1.74 to 1 10.2 dB (3/8 Heliax shorted) 2.0 to 1 So we see that with 100 FT of very good cable, even a infinite VSWR at the far end produces a VSWR at the input end of 2 to 1 or less, resulting in a mismatch loss of 0.48 dB or less. This is why the T-bolt and other manufacturers state that the cable impedance simply does not matter. I did not treat the other consideration which is overall noise figure. This is because the receiver and antenna designers use such high gain pre-amplifiers in the antenna. If you follow this up on the Web you can find that with enough preamp gain (subtracting the cable loss)the effect of the cable and the noise figure of the second stage (the receiver) is totally swamped and the first stage noise figure is maintained. By the way in the basic noise figure equation the value for NF is an absolute number - it is not in db. The short version is that if you have a 30 dB preamp in the antenna and 10 dB of cable loss, you are still 20 db to the good. The noise figure is degraded by (crudely) 1/20 dB or roughly 1%. Obviously more preamp gain is better as is a shorter or better cable, but the basic system design assumes use of economic cable like RG-6. -73 john k6iql ___ 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] Least costly 10 MHz reference solution
Russ, Welcome! On 01/23/2013 05:48 PM, Russ Ramirez wrote: Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places (10 ppb?), so anything that is good to a few ppb is certainly adequate for what I am looking for. I have a OCXO unit that is voltage adjustable - for example, adjusting this to 10.000 MHz per my HP 5334A requires -12.71V. So the simple (maybe) question is, should I go for a Rubidium disciplined unit, or go with a home-brew GPSDO solution using the Vectron OCXO I already have? My main cause of confusion is ignorance concerning all the GPS solutions out there with 1pps outputs, to use in a GPSDO, and which ones jitter too much to be useful (solutions under $50 exist). Thanks in advance. A rubidium or GPSDO such as Thunderbolt can be found fairly cheaply. If you go for a Thunderbolt, get one with antenna as a kit, mostly because it is a handy way to get started. For better stability you can get a better antenna later, if the need would occur. The rubidium should give you the precision you need straight out of the box, unless it has issues. In order to control if it has issues, having the ability to at least compare to GPS becomes obvious, so you end up wanting that GPSDO anyway. You can get both for reachable money anyway, if you look around long enough. Doing a home-cooked GPSDO is fun naturally, and there is an art in low-budget designs giving fair amount of performance. 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] One Kg Quartz Resonator
On 1/22/2013 8:25 PM, time-nuts-requ...@febo.com wrote: Interestingly, this experiment may also become the first time we ever needed to know PI better than 355/113 outside abstract mathematics. Good thing this is easy now. It took a long TIME, but I ran PI out to 80 billion points using a 3.5Ghz quad core processor recently. (Note: references to Time and Frequency included to keep things on topic :) ) Dan ___ 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] Least costly 10 MHz reference solution
No question, You want a GPSDO. Yes you can buy a Rb or a high-end OCXO but neither of these is connected to any kind of standard and will need to be calibrated to be of use. The GPS serves as a standard and you need that before the other options. The next question is which GPSDO? For most people that would be a Thunderbolt but the prices are going up on those. Then you will need a good antenna installation. On Wed, Jan 23, 2013 at 8:48 AM, Russ Ramirez russ.rami...@gmail.com wrote: Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places (10 ppb?), so anything that is good to a few ppb is certainly adequate for what I am looking for. I have a OCXO unit that is voltage adjustable - for example, adjusting this to 10.000 MHz per my HP 5334A requires -12.71V. So the simple (maybe) question is, should I go for a Rubidium disciplined unit, or go with a home-brew GPSDO solution using the Vectron OCXO I already have? My main cause of confusion is ignorance concerning all the GPS solutions out there with 1pps outputs, to use in a GPSDO, and which ones jitter too much to be useful (solutions under $50 exist). Thanks in advance. Russ K0WFS ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Least costly 10 MHz reference solution
Hi Not to pick nits, but 7 decimal places at what input frequency? Seven places is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb. The distinction is significant, since it crosses a boundary. At 10 ppb a free running Rb is fine with no adjustments. At 1 ppb, some adjustment might be needed. You might also want a standard that's 5X better than the expected result. That would get you into the 2 to 0.2 ppb range. Lots of fiddly little details... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Russ Ramirez Sent: Wednesday, January 23, 2013 11:48 AM To: time-nuts@febo.com Subject: [time-nuts] Least costly 10 MHz reference solution Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places (10 ppb?), so anything that is good to a few ppb is certainly adequate for what I am looking for. I have a OCXO unit that is voltage adjustable - for example, adjusting this to 10.000 MHz per my HP 5334A requires -12.71V. So the simple (maybe) question is, should I go for a Rubidium disciplined unit, or go with a home-brew GPSDO solution using the Vectron OCXO I already have? My main cause of confusion is ignorance concerning all the GPS solutions out there with 1pps outputs, to use in a GPSDO, and which ones jitter too much to be useful (solutions under $50 exist). Thanks in advance. Russ K0WFS ___ 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] Thunderbolt Monitor
You can't compare the size of a Windows binary to a uP RAM. If you look inside the .exe file you see that 90% of it is dealing with the Windows OS. The actual computations are very, very small and don't use even half the 16KB Flash. On Wed, Jan 23, 2013 at 10:10 AM, Bob Camp li...@rtty.us wrote: Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect you would get about 5% of it into a MSP430. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 11:44 AM To: Major L. McGee III; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89
Hi Magnus, The idea of not having to wonder if I can trust the source, i.e. a GPSDO, is appealing for sure, and one more antenna isn't going to hurt :-) Thanks for your reply. Russ On Wed, Jan 23, 2013 at 1:45 PM, time-nuts-requ...@febo.com wrote: Message: 5 Date: Wed, 23 Jan 2013 20:17:01 +0100 From: Magnus Danielson mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Least costly 10 MHz reference solution Message-ID: 5100372d.30...@rubidium.dyndns.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed Russ, Welcome! A rubidium or GPSDO such as Thunderbolt can be found fairly cheaply. If you go for a Thunderbolt, get one with antenna as a kit, mostly because it is a handy way to get started. For better stability you can get a better antenna later, if the need would occur. The rubidium should give you the precision you need straight out of the box, unless it has issues. In order to control if it has issues, having the ability to at least compare to GPS becomes obvious, so you end up wanting that GPSDO anyway. You can get both for reachable money anyway, if you look around long enough. Doing a home-cooked GPSDO is fun naturally, and there is an art in low-budget designs giving fair amount of performance. 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.
Re: [time-nuts] Thunderbolt Monitor
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Absolutely - however, I suspect the MSP430 might be a little too small. I'd be looking at something like a Raspberry Pi and a serially attached screen. Adafruit do some lovely boards like these: http://www.adafruit.com/products/1115 It's not $5 but it's not exactly exorbitant. Or just use a Pi and a HDMI capable TV if you have one spare. Cheers, James Harrison On 23/01/2013 19:55, Chris Albertson wrote: You can't compare the size of a Windows binary to a uP RAM. If you look inside the .exe file you see that 90% of it is dealing with the Windows OS. The actual computations are very, very small and don't use even half the 16KB Flash. On Wed, Jan 23, 2013 at 10:10 AM, Bob Camp li...@rtty.us wrote: Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect you would get about 5% of it into a MSP430. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 11:44 AM To: Major L. McGee III; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.17 (MingW32) iEYEARECAAYFAlEASkoACgkQ22kkGnnJQAzUCgCfT5V3oRBoq/FfHmv6dZSDet2k fuUAnRZO3g6eU+V8Zn1ubupYDbNeywef =GHLi -END PGP SIGNATURE- ___ 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] time-nuts Digest, Vol 102, Issue 89
Hi Bob, That's a good point and not nit picking. While my particular HP 5334A counter (sans 1.3 GHz channel C option) only measures with this kind of resolution at lower frequencies, I will be using the source for my Fluke 6060B (instead of the 5334A's output as I do now) which can produce a 1050 MHz signal, and of course any future test equipment needs. So yeah, I suppose I'd appreciate having a 1 ppb accuracy now that I've thought about it. Thanks. Russ On Wed, Jan 23, 2013 at 1:45 PM, time-nuts-requ...@febo.com wrote: Message: 8 Date: Wed, 23 Jan 2013 14:48:36 -0500 From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Subject: Re: [time-nuts] Least costly 10 MHz reference solution Message-ID: f3cc4b394995429a86320f617f42d...@vectron.com Content-Type: text/plain; charset=US-ASCII Hi Not to pick nits, but 7 decimal places at what input frequency? Seven places is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb. The distinction is significant, since it crosses a boundary. At 10 ppb a free running Rb is fine with no adjustments. At 1 ppb, some adjustment might be needed. You might also want a standard that's 5X better than the expected result. That would get you into the 2 to 0.2 ppb range. Lots of fiddly little details... Bob ___ 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 Monitor
Hi I do believe I included the size of the DOS exe as well as the Windows version. Both get *some* support from the OS that you will need to implement in your code. It's not just program space either. You only have 512 bytes of RAM on the larger of the two processors. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 2:55 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor You can't compare the size of a Windows binary to a uP RAM. If you look inside the .exe file you see that 90% of it is dealing with the Windows OS. The actual computations are very, very small and don't use even half the 16KB Flash. On Wed, Jan 23, 2013 at 10:10 AM, Bob Camp li...@rtty.us wrote: Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect you would get about 5% of it into a MSP430. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 11:44 AM To: Major L. McGee III; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Is there any way to use a TIC to measure time of reflection on a PCB?
On 01/23/2013 03:48 PM, David Kirkby wrote: There's a fairly interesting (to me at least), discussion on an Agilent forum devoted to the calibration of vector network analyzers. http://www.home.agilent.com/owc_discussions/thread.jspa?threadID=34809tstart=0 The title of the thread is Coefficients of fringing capacitance polynomial A student needs to find the open-circuit fringing capacitance of a piece of microstrip line. For this he needs to know the time between the reference plane of the SMA connector and the open circuit microstrip. An obvious way to do this is with a vector network analyzer with a time-domain option. In HP/Agilent VNAs, this is option 010. The student has access to an obsolete and unsuported HP 8753C 6 GHz VNA, but it does not have the time-domain option. I thought he might be able to convince someone at Agilent to give the uni this option, which is just enabled by software. So far that has not worked. I did offer to help with access to my HP 8720D VNA which has the time-domain option. But more to the point, one of Agilent's VNA gurus, Dr. Joel Dunsmore, the author of this book http://www.amazon.co.uk/Handbook-Microwave-Component-Measurements-Techniques/dp/1119979552 has said the time domain resolution would not be sufficent on a 6 GHz VNA for this - he would need a resolution of around 100 ps, which would need a 20 GHz VNA. My HP 8720D VNA is a 20 GHz model, but I don't have a calibration kit for greater than 9 GHz. I was just wondering if there was any way a time-interval counter could help.I can't think of a way, and I'm 95% sure there is not a way, but a TIC would offer the timing resolution better than is achievable with a 6 GHz VNA. I suspect one would need a directional coupler to look at the reflected wave, and there is no way to correct for systematic errors like there is with a VNA. If I had an HP or Agilent 85052B Standard Mechanical Calibration Kit, (DC to 26.5), then my VNA would just about have enough time-domain resolution, but I don't have such a cal kit, and they are not exactly cheap, even on eBay. I really think he should use a TDR for that stuff. Besides, there is nothing very magic about the time domain option, it should be possible to cook the software yourself, but I suspect someone has already done it. My TDR would probably suffice, the actual measurements is done in minutes, need to work on the hard-copy details, but it is fairly easy to pull the data over RS-232 or GPIB. 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.
Re: [time-nuts] time-nuts Digest, Vol 102, Issue 90
Yep, been there, done that. I'm a Ham and have several receivers. However, that method falls a bit short for what I think I need and have decided to look for something a bit better. What has been unknown to me is what result I might get if I take a GPS solution such as this: http://www.adafruit.com/products/746 and add the antenna and such, plus design a circuit to discipline one of the OXCO's I have. This unit does have a 1 pps output. I suspect more than resolution to X digits, there's also the question of whether a (low end) unit such as this will reliably stay locked. On the other hand, if I purchase something off-the-shelf that is good to 10 digits, at least I know what I'm getting. Thanks for your reply. Russ K0WFS On Wed, Jan 23, 2013 at 4:02 PM, time-nuts-requ...@febo.com wrote: Message: 1 Date: Wed, 23 Jan 2013 11:48:29 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Least costly 10 MHz reference solution Message-ID: cabbxvhudh5hp6xorwqh6pth_s17vbgptnr-fdtao1zhr1rh...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places At 10,000,000 Hz your required accuracy is 1Hz. You can get to that level by zero beating to WWV. This is very inexpensive, free if you already have a radio. What you do is adjust the frequency of any local oscillator until the beat frequency with WWV is greater then one Hz. You can either listen or use a scope Most people here are wanting 10 to 13 digits and that requires more work but 7 digitas is way easy. That said you might just as well get the GPS which gives about 13 digits over a longish measurement period. But if you are looking for the lowest cost way to get to 1Hz the old methods will do that. In fact you can zero-beat any radio station that has a known frequency. All comercial braodcast stations are good enough but WWV just happens to use a round number carrier freq. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89
Hi Russ, When testing rubidiums in my lab yesterday, I found that my main counter-pair (a CNT-90 and a SR-620) was way off, it seems like my primary GPSDO (a Thunderbolt) didn't like the situation. Will have to check things. A few rounds more. Also considering that I have a few (more) cesiums to test now. Ah well. So, I will have to check on my GPSDO... luckily I have several :) Cheers, Magnus On 01/23/2013 09:28 PM, Russ Ramirez wrote: Hi Magnus, The idea of not having to wonder if I can trust the source, i.e. a GPSDO, is appealing for sure, and one more antenna isn't going to hurt :-) Thanks for your reply. Russ On Wed, Jan 23, 2013 at 1:45 PM,time-nuts-requ...@febo.com wrote: Message: 5 Date: Wed, 23 Jan 2013 20:17:01 +0100 From: Magnus Danielsonmag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] Least costly 10 MHz reference solution Message-ID:5100372d.30...@rubidium.dyndns.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed Russ, Welcome! A rubidium or GPSDO such as Thunderbolt can be found fairly cheaply. If you go for a Thunderbolt, get one with antenna as a kit, mostly because it is a handy way to get started. For better stability you can get a better antenna later, if the need would occur. The rubidium should give you the precision you need straight out of the box, unless it has issues. In order to control if it has issues, having the ability to at least compare to GPS becomes obvious, so you end up wanting that GPSDO anyway. You can get both for reachable money anyway, if you look around long enough. Doing a home-cooked GPSDO is fun naturally, and there is an art in low-budget designs giving fair amount of performance. 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] time-nuts Digest, Vol 102, Issue 89
Russ, You might want to consider stopping to think about it now. Otherwise, you'll wind up with a Cesium Standard to check the GPSDO, a collection of OCXO's and Rb's to see which is the best, not to mention all the test equipment needed to carry out those measurements, and, perhaps, a MASER to check the CS. Having done what you are contemplating, I vote for the GPSDO and a TBolt is a great choice. I would recommend a linear power source rather than a 'switching' power supply. Otherwise, get a switching power supply with higher voltages than needed and use some linear regulators downstream to generate the +12, -12, and +5 needed for the TBolt. Good luck. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Russ Ramirez Sent: Wednesday, January 23, 2013 2:24 PM To: time-nuts@febo.com Subject: Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89 Hi Bob, That's a good point and not nit picking. While my particular HP 5334A counter (sans 1.3 GHz channel C option) only measures with this kind of resolution at lower frequencies, I will be using the source for my Fluke 6060B (instead of the 5334A's output as I do now) which can produce a 1050 MHz signal, and of course any future test equipment needs. So yeah, I suppose I'd appreciate having a 1 ppb accuracy now that I've thought about it. Thanks. Russ On Wed, Jan 23, 2013 at 1:45 PM, time-nuts-requ...@febo.com wrote: Message: 8 Date: Wed, 23 Jan 2013 14:48:36 -0500 From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Subject: Re: [time-nuts] Least costly 10 MHz reference solution Message-ID: f3cc4b394995429a86320f617f42d...@vectron.com Content-Type: text/plain; charset=US-ASCII Hi Not to pick nits, but 7 decimal places at what input frequency? Seven places is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb. The distinction is significant, since it crosses a boundary. At 10 ppb a free running Rb is fine with no adjustments. At 1 ppb, some adjustment might be needed. You might also want a standard that's 5X better than the expected result. That would get you into the 2 to 0.2 ppb range. Lots of fiddly little details... Bob ___ 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] time-nuts Digest, Vol 102, Issue 89
Don't forget the ion fountain to check the H Maser :-) Sent from my iPhone On Jan 23, 2013, at 5:35 PM, J. L. Trantham jlt...@att.net wrote: Russ, You might want to consider stopping to think about it now. Otherwise, you'll wind up with a Cesium Standard to check the GPSDO, a collection of OCXO's and Rb's to see which is the best, not to mention all the test equipment needed to carry out those measurements, and, perhaps, a MASER to check the CS. Having done what you are contemplating, I vote for the GPSDO and a TBolt is a great choice. I would recommend a linear power source rather than a 'switching' power supply. Otherwise, get a switching power supply with higher voltages than needed and use some linear regulators downstream to generate the +12, -12, and +5 needed for the TBolt. Good luck. Joe -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Russ Ramirez Sent: Wednesday, January 23, 2013 2:24 PM To: time-nuts@febo.com Subject: Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89 Hi Bob, That's a good point and not nit picking. While my particular HP 5334A counter (sans 1.3 GHz channel C option) only measures with this kind of resolution at lower frequencies, I will be using the source for my Fluke 6060B (instead of the 5334A's output as I do now) which can produce a 1050 MHz signal, and of course any future test equipment needs. So yeah, I suppose I'd appreciate having a 1 ppb accuracy now that I've thought about it. Thanks. Russ On Wed, Jan 23, 2013 at 1:45 PM, time-nuts-requ...@febo.com wrote: Message: 8 Date: Wed, 23 Jan 2013 14:48:36 -0500 From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Subject: Re: [time-nuts] Least costly 10 MHz reference solution Message-ID: f3cc4b394995429a86320f617f42d...@vectron.com Content-Type: text/plain; charset=US-ASCII Hi Not to pick nits, but 7 decimal places at what input frequency? Seven places is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb. The distinction is significant, since it crosses a boundary. At 10 ppb a free running Rb is fine with no adjustments. At 1 ppb, some adjustment might be needed. You might also want a standard that's 5X better than the expected result. That would get you into the 2 to 0.2 ppb range. Lots of fiddly little details... Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 102, Issue 89
On 01/23/2013 11:35 PM, J. L. Trantham wrote: Russ, You might want to consider stopping to think about it now. Otherwise, you'll wind up with a Cesium Standard to check the GPSDO, a collection of OCXO's and Rb's to see which is the best, not to mention all the test equipment needed to carry out those measurements, and, perhaps, a MASER to check the CS. I've come to the level that besides having things properly rigged, the lack of H-masers is annoying :) 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.
Re: [time-nuts] Is there any way to use a TIC to measure time of reflection on a PCB?
On 23 January 2013 15:22, Jim Lux jim...@earthlink.net wrote: On 1/23/13 6:48 AM, David Kirkby wrote: A student needs to find the open-circuit fringing capacitance of a piece of microstrip line. For this he needs to know the time between the reference plane of the SMA connector and the open circuit microstrip. Can he build multiple microstrips with known distances, and measure them all and solve for it that way? I'm not sure how that would help. The basic problem is that there is some discontinuity of impedance between the microstrip and SMA connector. The open reflects 99% of the incident power, and that discontinuity then causes the power to go back to the open. So it seems to me one needs some form of time-gating. Also there's the issue of how reproducible it would be to solder SMA connectors to a board. An obvious way to do this is with a vector network analyzer with a time-domain option. In HP/Agilent VNAs, this is option 010. The student has access to an obsolete and unsuported HP 8753C 6 GHz VNA, but it does not have the time-domain option. Does it have the measurement plane offset option? Yes - it is called port extensions in HP language. I'm not in front of my old analyzer in the lab (8720C.. no disk drive), and it does have the transform option, but I'm not sure you need that option to have the dial an offset in the calibration. I've used that to move the reference plane from the connectors at the edge of a board to the device on the board: testing a vector modulator with the display in polar coordinate mode, for instance.. you keep turning the knob til the display is a dot, not a circle That is not really the right way to do it, since there will be some fringing capacitance. You have not removed that - just appeared to have done, but have faked that by setting the offset delay. You have chosen an offset delay of less than the true value. But to a first degree, delay in the transmission line and delay caused by the capacitance are similar. See: What measurement uncertainty is called for here? It's an undergraduate project. I don't suppose he has been given such data. Can you make your own limited purpose cal kit? The open is the challenge. Shorts, loads, and thrus are fairly straightforward. The idea of his project is to characterise devices - I'm guessing surface mount. For this he needs a calibrated microstrip line. So the whole point is to characterise this. As you say, the open is the challenge. Knowing what the length to the open is, you an dial that into a VNA as a port extension, then read off the capacitance of the open since you have moved the reference plane to there. However, if you chose a different value of port extension, you will read a different value of capacitance. Also the fringing capacitance is frequency dependant - it is not a constant, though it is quite close to being a constant. I believe he has arrived at a offset length, but it has been pointed out he had done this the wrong way. One really needs the TDR option. The procedure would be: * Use the TDR, which is basically an inverse Fourier Transform. * Put a gate around the reflection from the open. * Transform the data in the gate back the the frequency domain. This allows one to look at the frequency domain response of the open, whilst ignoring that due to other discontinuity. But of course to do this one needs sufficient discrimination in time, to look at just the open, and not anything else. His VNA does not have the frequency response to do that, even if he gets the TDR option. He has arrived at an offset delay, using a method similar to what you described. But it has pointed out to him that the idea is not to make the open look a spot, but to determine what the capacitance is. In that case, the open does not look like a spot. In fact, on my 3.5 mm kit, the open actually becomes a short at one frequency, but then the short has become an open. I see about 200 degree of phase shift of both the open and short over the range 50 MHz to 9 GHz. It does not matter, as long as the phase of the open and short remain around 180 degrees apart. Once he arrived at an offset, he moved the reference plane there, then measured the capacitance as a function of frequency. He then fitted that to the equation of the form C = C0 10^-15 + C1 10^-27 f + C2 10^-26 f^2 + C3 10^-45 f^3. Once he tried to enter C0, C1, C2 and C3 into the VNA, as a user-defined calibration kit, he was unable to do this, as the constants are too large. I think he has got the offset wrong, so he has moved the reference plane to the wrong place, so the constants are incorrect and unusable. Maybe you have to collect the uncalibrated data with the cal standards and do the cal in post processing in Matlab or something. I think his basic issue is that the time domain discrimination is too large. I rather suspect an Agilent employee might have given him the code to enable the TDR, but Joel Dunsmore has determined
Re: [time-nuts] Thunderbolt Monitor
You realy can't know if a processor is to large or small until you have at least a outline of the software design.In this case the uP is reading test from a serial port at a low data rate. It is running a filter and sending a small amount of text back to the GPS. So the load on the CPU is trivial.The harder part is sending that data off to a larger computer, likely using Ethernet. It coud use UDP at one second per packet. Depends on how much you want to do on the device. That MSP430 is going to be used to interface an anemometer (wind cups) Mymethod normally is to do as much development as I can on a big computer like my Mac. Then move the software down to the target environment. TI sells another Launch pad for $18 that uses an ARM. This is a much more capable CPU but for data logging maybe over kill. But if the plan was to host a web server you'd need something like the ARM. But actually the AVR inside the Arduino can run a web interface. but with ARM powered LaunchPads for $18 I'd go with that. On Wed, Jan 23, 2013 at 12:38 PM, James Harrison ja...@talkunafraid.co.uk wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Absolutely - however, I suspect the MSP430 might be a little too small. I'd be looking at something like a Raspberry Pi and a serially attached screen. Adafruit do some lovely boards like these: http://www.adafruit.com/products/1115 It's not $5 but it's not exactly exorbitant. Or just use a Pi and a HDMI capable TV if you have one spare. Cheers, James Harrison On 23/01/2013 19:55, Chris Albertson wrote: You can't compare the size of a Windows binary to a uP RAM. If you look inside the .exe file you see that 90% of it is dealing with the Windows OS. The actual computations are very, very small and don't use even half the 16KB Flash. On Wed, Jan 23, 2013 at 10:10 AM, Bob Camp li...@rtty.us wrote: Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect you would get about 5% of it into a MSP430. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 11:44 AM To: Major L. McGee III; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.17 (MingW32)
Re: [time-nuts] One Kg Quartz Resonator
Il 2013-01-23 13:39 Bob Camp ha scritto: the mode that the bar is resonating in, it's a bit hard to guess where the nodes will be. Just looking at the bar, you wouldn't *guess* that the end points would be nodes... Bob Sorry Bob I didnt understand last part. You say that the end faces are nodes that move very little? Or that it's hard to tell the way they move? I asked that because reading the patent, I understand that the plates are trimmed to stay near the rod and not touching it, to give costant air reflection behaviour. And talks about supersonic movement of the air, so I was wondering why that was only a problem on end faces and not on other long faces of the rod. Thanks, Fabio. ___ 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] IEEE P1588 Study Call for Participation - Standard for a Precision Clock Synchronization Protocol
This announcement landed in my in-box today, I thought it might be of interest to time nuts: - The IEEE P1588 Study Group (SG) announces a Call for Participation (CFP) to develop a Project Authorization Request (PAR) for the revision of IEEE 1588™ -2008, Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. IEEE P1588 SG is sponsored by the Instrumentation and Measurement Society (IMS)/TC-9. IEEE 1588-2008 is also published as International Standard IEC/IEEE 61588, which was processed through subcommittee 65C: Industrial networks, of IEC technical committee 65: Industrial-process measurement, control and automation. IEEE P1588 SG is seeking participants with a technical or commercial interest in IEEE 1588 -2008. We ask that you please share this CFP with any colleagues that are eligible to participate. - Full details are at: http://standards.ieee.org/email/2013_01_cfp1588_web.html Dan Schultz N8FGV ___ 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] Is there any way to use a TIC to measure time of reflection on a PCB?
On 01/23/2013 07:03 PM, David Kirkby wrote: On 23 January 2013 15:22, Jim Luxjim...@earthlink.net wrote: On 1/23/13 6:48 AM, David Kirkby wrote: A student needs to find the open-circuit fringing capacitance of a piece of microstrip line. For this he needs to know the time between the reference plane of the SMA connector and the open circuit microstrip. Can he build multiple microstrips with known distances, and measure them all and solve for it that way? I'm not sure how that would help. The basic problem is that there is some discontinuity of impedance between the microstrip and SMA connector. The open reflects 99% of the incident power, and that discontinuity then causes the power to go back to the open. So it seems to me one needs some form of time-gating. Also there's the issue of how reproducible it would be to solder SMA connectors to a board. An obvious way to do this is with a vector network analyzer with a time-domain option. In HP/Agilent VNAs, this is option 010. The student has access to an obsolete and unsuported HP 8753C 6 GHz VNA, but it does not have the time-domain option. Does it have the measurement plane offset option? Yes - it is called port extensions in HP language. I'm not in front of my old analyzer in the lab (8720C.. no disk drive), and it does have the transform option, but I'm not sure you need that option to have the dial an offset in the calibration. I've used that to move the reference plane from the connectors at the edge of a board to the device on the board: testing a vector modulator with the display in polar coordinate mode, for instance.. you keep turning the knob til the display is a dot, not a circle That is not really the right way to do it, since there will be some fringing capacitance. You have not removed that - just appeared to have done, but have faked that by setting the offset delay. You have chosen an offset delay of less than the true value. But to a first degree, delay in the transmission line and delay caused by the capacitance are similar. See: What measurement uncertainty is called for here? It's an undergraduate project. I don't suppose he has been given such data. Can you make your own limited purpose cal kit? The open is the challenge. Shorts, loads, and thrus are fairly straightforward. The idea of his project is to characterise devices - I'm guessing surface mount. For this he needs a calibrated microstrip line. So the whole point is to characterise this. As you say, the open is the challenge. Knowing what the length to the open is, you an dial that into a VNA as a port extension, then read off the capacitance of the open since you have moved the reference plane to there. However, if you chose a different value of port extension, you will read a different value of capacitance. Also the fringing capacitance is frequency dependant - it is not a constant, though it is quite close to being a constant. I believe he has arrived at a offset length, but it has been pointed out he had done this the wrong way. One really needs the TDR option. The procedure would be: * Use the TDR, which is basically an inverse Fourier Transform. * Put a gate around the reflection from the open. * Transform the data in the gate back the the frequency domain. This allows one to look at the frequency domain response of the open, whilst ignoring that due to other discontinuity. But of course to do this one needs sufficient discrimination in time, to look at just the open, and not anything else. His VNA does not have the frequency response to do that, even if he gets the TDR option. He has arrived at an offset delay, using a method similar to what you described. But it has pointed out to him that the idea is not to make the open look a spot, but to determine what the capacitance is. In that case, the open does not look like a spot. In fact, on my 3.5 mm kit, the open actually becomes a short at one frequency, but then the short has become an open. I see about 200 degree of phase shift of both the open and short over the range 50 MHz to 9 GHz. It does not matter, as long as the phase of the open and short remain around 180 degrees apart. Once he arrived at an offset, he moved the reference plane there, then measured the capacitance as a function of frequency. He then fitted that to the equation of the form C = C0 10^-15 + C1 10^-27 f + C2 10^-26 f^2 + C3 10^-45 f^3. Once he tried to enter C0, C1, C2 and C3 into the VNA, as a user-defined calibration kit, he was unable to do this, as the constants are too large. I think he has got the offset wrong, so he has moved the reference plane to the wrong place, so the constants are incorrect and unusable. Maybe you have to collect the uncalibrated data with the cal standards and do the cal in post processing in Matlab or something. I think his basic issue is that the time domain discrimination is too large. I rather suspect an Agilent employee might have given him the code to enable the TDR,
Re: [time-nuts] Thunderbolt Monitor
Hi My original comment was in reply to your suggestion of porting Lady Heather into a MSP430. I took that to be your outline of your project. My reply was simply that Lady Heather is a very complex and full featured program. It does *way* more than just look at a serial stream and tell you a few simple things. If the project has now changed into something else, then so be it. Bob On Jan 23, 2013, at 6:10 PM, Chris Albertson albertson.ch...@gmail.com wrote: You realy can't know if a processor is to large or small until you have at least a outline of the software design.In this case the uP is reading test from a serial port at a low data rate. It is running a filter and sending a small amount of text back to the GPS. So the load on the CPU is trivial.The harder part is sending that data off to a larger computer, likely using Ethernet. It coud use UDP at one second per packet. Depends on how much you want to do on the device. That MSP430 is going to be used to interface an anemometer (wind cups) Mymethod normally is to do as much development as I can on a big computer like my Mac. Then move the software down to the target environment. TI sells another Launch pad for $18 that uses an ARM. This is a much more capable CPU but for data logging maybe over kill. But if the plan was to host a web server you'd need something like the ARM. But actually the AVR inside the Arduino can run a web interface. but with ARM powered LaunchPads for $18 I'd go with that. On Wed, Jan 23, 2013 at 12:38 PM, James Harrison ja...@talkunafraid.co.uk wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Absolutely - however, I suspect the MSP430 might be a little too small. I'd be looking at something like a Raspberry Pi and a serially attached screen. Adafruit do some lovely boards like these: http://www.adafruit.com/products/1115 It's not $5 but it's not exactly exorbitant. Or just use a Pi and a HDMI capable TV if you have one spare. Cheers, James Harrison On 23/01/2013 19:55, Chris Albertson wrote: You can't compare the size of a Windows binary to a uP RAM. If you look inside the .exe file you see that 90% of it is dealing with the Windows OS. The actual computations are very, very small and don't use even half the 16KB Flash. On Wed, Jan 23, 2013 at 10:10 AM, Bob Camp li...@rtty.us wrote: Hi Heathdos.exe 123 KB Heather.exe 572 KB Server.exe 176 KB (each would be plus what ever they pull from DLL's and the OS) Ti LaunchPad MSP-EXP430G2 - MSP 430 version ($4.30): MSP-430G2553 Microcontroller: 16 KB flash 512 B RAM MSP-430G2452 Microcontroller: 8 KB flash 256 B RAM I suspect you would get about 5% of it into a MSP430. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, January 23, 2013 11:44 AM To: Major L. McGee III; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thunderbolt Monitor I was looking into porting much of LH into an Arduino or TI Launch Pad (msp430) And then a display would be web based. But then I decided to go back to grad school and there went any free time. But I think that is that way to go. The TB is best kept in some light-out closet and who wants to stand of a step stool to read an LCD when a web interface could put a better display on your smart phone or computer I did just buy a TI Launchpad. For $4.30 shipping included I could not resist but I have in mind a MUCH smaller project On Wed, Jan 23, 2013 at 8:31 AM, Major L. McGee III maj...@sc.rr.com wrote: I have been following this on the list for a while now and was curious if anyone is actively working on a open source monitor. I see the one made by Adam VK4GHZ is no longer being sold. This got me back on track for wanting to make one of my own. I have been using either tbmon or lady heather but always have issues with a usb to serial converter when I start the computer. It will go haywire and cause it to freeze and make the mouse malfunction. Once I disconnect the converter (I have tried other makes as well) it works fine. Usually I can reconnect the converter and things will work again. What I would like to do is make a 2 or 4 line lcd readout to display various info. I really liked VK4GHZ's page type selector knob. I can see that being very useful. On a youtube video by n6vmo said the thunderbolt used a ASCII Hex and needs to be converted by using 64 bit floating point math. So are any of you currently working on this or have decided to quit and have any information to share? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California
Re: [time-nuts] One Kg Quartz Resonator
Hi Not having a bar sitting here to play with, it's hard to tell how the bar is mounted. If it's mounted by the points on the disks, then they must be non-moving nodal points. If that's what they are, I'm a bit surprised that the bar has nodes at the ends. Bob On Jan 23, 2013, at 6:57 PM, Fabio Eboli fabi...@quipo.it wrote: Il 2013-01-23 13:39 Bob Camp ha scritto: the mode that the bar is resonating in, it's a bit hard to guess where the nodes will be. Just looking at the bar, you wouldn't *guess* that the end points would be nodes... Bob Sorry Bob I didnt understand last part. You say that the end faces are nodes that move very little? Or that it's hard to tell the way they move? I asked that because reading the patent, I understand that the plates are trimmed to stay near the rod and not touching it, to give costant air reflection behaviour. And talks about supersonic movement of the air, so I was wondering why that was only a problem on end faces and not on other long faces of the rod. Thanks, Fabio. ___ 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] Better gps antennas than a Symmetricom 58532A
On 1/23/13 7:26 AM, li...@lazygranch.com wrote: For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, you know exactly the application. You assume that the antenna designer actually tried to hit a particular Z. They may have been going for about 60 ohms which would be about 1.2:1 for both 50 and 75 ohms. Or, they were more worried about optimizing the pattern or axial ratio, and the Z could be good enough. I've got a SWR plot from a passive L1/L2 antenna here (specified as better than 1.5:1) and it varies somewhat randomly with no apparent pattern between 1.5:1 and 1.1:1, and is about 1.3:1 at L1. Another antenna (same mfr, same model, slightly different installation and cable) ripples between 1.45:1 and 1.05:1, mostly oscillating around 1.2:1. At L1 it's about 1.1:1 It meets the spec everywhere. The loading could effect the antenna pattern if it were not for the preamp. It is unlikely that the impedance presented at the feedpoint of an single feed antenna will change the pattern, particularly for something low gain like a GPS. That is, there's no physical way it could affect it. The pattern is determined by the currents distributed around the physical antenna, and they have a fixed (complex) ratio to the current at the feedpoint. all an impedance change would do is change that current, but then everything changes together and the pattern is unchanged. ___ 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] Better gps antennas than a Symmetricom 58532A
On 1/23/13 8:50 PM, Jim Lux wrote: On 1/23/13 7:26 AM, li...@lazygranch.com wrote: For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, you know exactly the application. You assume that the antenna designer actually tried to hit a particular Z. They may have been going for about 60 ohms which would be about 1.2:1 for both 50 and 75 ohms. Or, they were more worried about optimizing the pattern or axial ratio, and the Z could be good enough. I've got a SWR plot from a passive L1/L2 antenna here (specified as better than 1.5:1) and it varies somewhat randomly with no apparent pattern between 1.5:1 and 1.1:1, and is about 1.3:1 at L1. Another antenna (same mfr, same model, slightly different installation and cable) ripples between 1.45:1 and 1.05:1, mostly oscillating around 1.2:1. At L1 it's about 1.1:1 forgot.. 1-1.8 GHz measurement span It meets the spec everywhere. ___ 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] Better gps antennas than a Symmetricom 58532A
I doubt the impedance would be designed so nobody gets a right match. Anyway, the geometric mean, which is how you would do such a compromise is 61.24 ohms. -Original Message- From: Jim Lux jim...@earthlink.net Sender: time-nuts-boun...@febo.com Date: Wed, 23 Jan 2013 20:50:00 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Better gps antennas than a Symmetricom 58532A On 1/23/13 7:26 AM, li...@lazygranch.com wrote: For a single frequency use like GPS, the impedance should be close to the target. It is true for scanners and such, 50 ohms is quite nominal. (This notion of DC to daylight and maintaining 50 ohms is fantasy. ) But for a GPS, you know exactly the application. You assume that the antenna designer actually tried to hit a particular Z. They may have been going for about 60 ohms which would be about 1.2:1 for both 50 and 75 ohms. Or, they were more worried about optimizing the pattern or axial ratio, and the Z could be good enough. I've got a SWR plot from a passive L1/L2 antenna here (specified as better than 1.5:1) and it varies somewhat randomly with no apparent pattern between 1.5:1 and 1.1:1, and is about 1.3:1 at L1. Another antenna (same mfr, same model, slightly different installation and cable) ripples between 1.45:1 and 1.05:1, mostly oscillating around 1.2:1. At L1 it's about 1.1:1 It meets the spec everywhere. The loading could effect the antenna pattern if it were not for the preamp. It is unlikely that the impedance presented at the feedpoint of an single feed antenna will change the pattern, particularly for something low gain like a GPS. That is, there's no physical way it could affect it. The pattern is determined by the currents distributed around the physical antenna, and they have a fixed (complex) ratio to the current at the feedpoint. all an impedance change would do is change that current, but then everything changes together and the pattern is unchanged. ___ 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] Better gps antennas than a Symmetricom 58532A
On 1/23/13 9:45 PM, li...@lazygranch.com wrote: I doubt the impedance would be designed so nobody gets a right match. Anyway, the geometric mean, which is how you would do such a compromise is 61.24 ohms. I suspect that it's more like.. the mfr builds a prototype that has the right pattern, and tweaks it so that it meets the VSWR spec everywhere. They build the production prototype, paint it, check the VSWR again, and move on. Even for precision applications, they're more interested in things like phase center not moving too much as a function of look angle than match. ___ 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] atomic clock articles
A nice pair of articles on the origins and workings of atomic clocks in the January issue of Physics Today. Started off as an atomic interferometer developed by Norman Ramsey. dON -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
