Re: [time-nuts] Two V(in)s walk into a bar...
Hi The real answer is a bit complicated. (As in at least a week of class, I sitting in a refresher course now), Ground = no current in normal use Return = where the IC ground pin connects A lot of confusion goes on between return and ground. In about 99.99% of schematics return is miss-labeled as ground. In your case, you need to be careful about layout. Keeping circuits apart will take care of most of the problems. Unless you do some very odd things a single solid return plane in your board is the best way to go. On every board you see, that plane will be labeled ground plane. Bob Sent from my iPhone On Jun 24, 2015, at 4:54 PM, Neil Schroeder gign...@gmail.com wrote: Lets take a hypothetical device, like specifically a PRS10, but could be any time/freq device like a PLL or an amplifier or all of these. Isolating power supplies with some dexterity can greatly improve noise control, and less peformance related, can help us protect very very expensive circuits from their less bourgeois support ICs. Many of us may choose to implement them as modular devices for easy relocation or replacement. Main question: if I want to isolate the quiet and noisy power supplies, or just supply them differently, can they share a common return? The basic answer has to be yes. Eventually everything has to get back to ground, and the Earth itself is a fair equalizer of all things on it. I can clearly join analog and digital back at the input supply. But if I had them isolated, do those iso grounds have to stay with their iso supplies? Take the PRS10 - it has two cables for Vin - power and signal supplies - but only one return cable. Can i isolate, via transformers couplers what have you the two supplies yet return the common ground to one or the other? The signals handle themselves - they each have a ground wire of their own, or does that handle it ? Are each of those opportunities for a loop? I know it'd work with just keeping separate DVcc and AVcc supplies that join at some point, and then that return can join at the star ground like everyone else. If you are designing the module, you can handle the isolation inside and just have one input supply and return then isolate new supplies internally and eliminate the second cable. Or two in vcc, two out gnd. Those all make sense. I think the single return option on the PRS10 is what's hanging me up here. Does isolation offer any real further benefit than AVxx and DVxx that is even worth pursuing outside the extreme use cases? Lots of words. Thanks. NS ___ 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] Splitters for the GPS antenna
I initially tried using Dishtv splitters with qualified success. On closer examination the bandpass between dish 1 and dish2 is different and neither actually calmed to pass the GPS frequencies. And indeed I had significantly different path losses. I wanted a better solution. I did a brief search and found the following. The results are much better and the price was very reasonable. My path losses appear to be balanced and generally agree within 1dB, with at least 10 SV reporting 39 - 49dB. The splitter I tried has a claimed bandwidth of 40 to 2400 MHz and a all ports power pass. Of course you have to have the adaptors from type N to type F and type F to type SMA. I was able to find all of those on Amazon and don't forget some type F terminators, they are hard to find in local box stores. Hope this helps some of the new guys, like myself, to get their labs up a little quicker. Computer Network Accessories, Inc. 5520 Burkhardt Road Dayton, Ohio 45431 Web: www.CNAweb.com http://www.cnaweb.com/ Email: sa...@cnaweb.com Phone: 937-258-2708 - Fax: 937-258-2743 Product NamePart No.QuantityItem PriceTotal Price4 Way 2GHz Splitter w/ DC Pass72-2443$4.10$12.30 Subtotal:$12.30Shipping Handling:$7.35Tax:$0.00 -- Order Total:$19.65 -- S. Cash Olsen KD5SSJ ARRL Technical Specialist ___ 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] PCI-E Serial Card For Windows NTP?
I know next-to-nothing about Windows. Serial ports are pretty standard. I'd get the cheapest card. I'd probably pay a bit more for a second port. It might be handy tomorrow. One difference between chips is the depth of the FIFO. PCI card now come in two heights. Make sure you get the right one. The short ones don't have room for a second connector. (Some cards come with two face plates. You can swap in/out the other one if you can use a screwdriver.) The other thing to keep an eye on is interrupts from the Gigabit ethernet. With a lot of short packets, you can get in trouble spending all your CPU time in the interrupt handler. Some hardware is setup to batch interrupts. The idea is to delay an interrupt for a while in hopes that more packets will arrive and get processed as a batch. You may want to turn that off. It's a tradeoff between latency and CPU usage. You may be able to measure it with something like ping. -- 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] Two V(in)s walk into a bar...
From a 2012 discussion on time-nuts by M. Simon and Voker Esper: http://www.edn.com/design/analog/4394761/Successful-PCB-grounding-with-mixed-signal-chips---Part-1--Principles-of-current-flow There are 3 parts to the article - links are available at the end of every section to the next section. On Wed, Jun 24, 2015 at 11:54 PM, Neil Schroeder gign...@gmail.com wrote: Lets take a hypothetical device, like specifically a PRS10, but could be any time/freq device like a PLL or an amplifier or all of these. Isolating power supplies with some dexterity can greatly improve noise control, and less peformance related, can help us protect very very expensive circuits from their less bourgeois support ICs. Many of us may choose to implement them as modular devices for easy relocation or replacement. Main question: if I want to isolate the quiet and noisy power supplies, or just supply them differently, can they share a common return? The basic answer has to be yes. Eventually everything has to get back to ground, and the Earth itself is a fair equalizer of all things on it. I can clearly join analog and digital back at the input supply. But if I had them isolated, do those iso grounds have to stay with their iso supplies? Take the PRS10 - it has two cables for Vin - power and signal supplies - but only one return cable. Can i isolate, via transformers couplers what have you the two supplies yet return the common ground to one or the other? The signals handle themselves - they each have a ground wire of their own, or does that handle it ? Are each of those opportunities for a loop? I know it'd work with just keeping separate DVcc and AVcc supplies that join at some point, and then that return can join at the star ground like everyone else. If you are designing the module, you can handle the isolation inside and just have one input supply and return then isolate new supplies internally and eliminate the second cable. Or two in vcc, two out gnd. Those all make sense. I think the single return option on the PRS10 is what's hanging me up here. Does isolation offer any real further benefit than AVxx and DVxx that is even worth pursuing outside the extreme use cases? Lots of words. Thanks. NS ___ 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] Jackson labs fury gpsdo with docxo for sale
Hi I'm wondering if there is any interest in my Jackson labs fury (desktop version) with the docxo option. I purchased it new from Jackson Labs in 2012. It has sat on a shelf powered up for almost the entire time I have owned it. I've been very happy with the unit but I haven't made much use of it over the last year and don't foresee any future need for it. I'm not in a huge hurry to sell it but I would be looking for 1,250 USD plus insured shipping from Canada (also the buyer would need to pay any taxes or duties that are payable by the buyer.) I would include the power supply it shipped with from Jackson labs. I'm also looking at selling it via some other channels as well so it may be gone soon. Please contact me off list if you are interested in pursuing this. I'm happy to send photos and provide more details to an interested party. Thanks Mark Spencer m...@alignedsolutions.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.
Re: [time-nuts] windows and leap seconds
On Thu, Jun 25, 2015 at 6:43 AM, Tom Harris celephi...@gmail.com wrote: This is a FAST PUBLISH article created directly from within the Microsoft support organization. The information contained herein is provided as-is in response to emerging issues. As a result of the speed in making it available, the materials may include typographical errors and may be revised at any time without notice. Wasn't the leap second publicised 6 months in advance? Just below that: Article ID: 909614 - Last Review: January 16, 2015 - Revision: 8.0 So it _was_ fast published after they heard in Jan. And it will next be revised when the next leap second is announced. In between, we can ignore the problem :-) Every job takes only two minutes, if you wait till the last minute to do it. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ 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] PCI-E Serial Card For Windows NTP?
Hi, I'm still pursuing setting up a fairly accurate NTP server connected to my Nortel/Trimble GPSTM. So far I've been playing with a Raspberry Pi 2, and have made fairly good progress using a bunch of tweaks detailed by another member of this list. However, it has been noted that the Raspberry Pi has some limitations for this purpose, not the least of which is having a USB connected ethernet port. Consequently I am also looking at some other options. The GPSTM and the Raspberry Pi will be sharing a shelf with my server, which is running a Core i7-3770 @ 3.4Ghz and a 64-bit version of Windows 7 Ultimate. This machine is typically running at about 10 to 20% CPU usage, and it is extremely rare for the CPU usage to exceed 50%. It is also equipped with an Intel gigabit ethernet port, connected by PCI express bus. I expect this may perform a little better than the pi's 100Mb card which is connected by USB. I also suspect that the i7 will do a bit better in terms of interrupt latency. There is a driver available for Windows 7 which allows use of the DCD pin on a serial port for PPS. Sadly, this machines motherboard does not have a serial port, nor a parallel port. Not even a header for one. And this leads to my question. I am considering adding a PCI express serial port card to this machine, but I don't know how well they perform for this application. There are quite a few different cards available, ranging in cost from under $10 to over $50. I am wondering how well these cards work for this application in general, and if there are some cards which will work well and some which will work poorly or not at all. And of course, if there is major variation between the cards, I would like to know how to pick one which will work well. I do have a little experience with parallel port add on cards, as I run a CNC milling machine which uses the parallel port to control the machine. Most of the parallel add-on card you can buy work fine for a printer, but will not work at all for sending pulses to the CNC machine. Only a very few cards are full function parallel ports, and they are pricey. Before I waste $8 on a cheap serial port card, I want to make sure I'm not looking at the same situation. If it matters, I'm planning on a dual-port card. Thanks 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.
Re: [time-nuts] Two V(in)s walk into a bar...
Consider the equivalent circuit of a common ground for two separate supplies. Any resistance or inductance can cause the effective voltage of one supply to be affected by the other as the current drawn varies. This is assuming a common return to the ground star. Separate the returns and one supply does not affect the other. The star ground may jump around, but all circuits are affected equally. Like your subject line. Better than 'strings,' I'm afraid. Bill Hawkins -Original Message- From: Neil Schroeder Sent: Wednesday, June 24, 2015 4:55 PM -- % - (snip) Main question: if I want to isolate the quiet and noisy power supplies, or just supply them differently, can they share a common return? -- % - (snip) Lots of words. Thanks. NS ___ 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] PCI-E Serial Card For Windows NTP?
For Serial ports and Personal Computers (PCI or PCIe), work with LAVA Link in Toronto, Ontario Canada. http://lavalink.com The Chinese cheap add-on card is a mine field of bad designs or implementations. You will find that out (first hand) once you push the serial speed beyond 9600 baud, unreliable at 38.4 kbaud. In addition, they struggle with software drivers with various Windows versions. I have used LavaLink since 1984, when they started Canadian company, with MS and SCO Xenix on IBM AT (80286). The additional advantage, they are just across the border and support is very good. LavaLink 2 Vulcan Street Toronto, Ontario, M9W 1L2 CANADA T: 1-800-241-LAVA (5282) toll free in North America T: 416-674-5942 F: 416-674-8262 Skype: office.lavacomputers w9gb Sent from iPad Air ___ 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] Splitters for the GPS antenna
Sorry for the thread hi jack. I also have a lightly used Symmetricom 58535A dual port (one antenna, two receivers) gps splitter I would be happy to part with. Please contact me off list of interested in this and perhaps we can come an agreement. It's fairly heavy so shipping may be pricey. Thanks Mark Spencer m...@alignedsolutions.com Sent from my iPhone On Jun 25, 2015, at 6:18 AM, Cash Olsen radio.kd5...@gmail.com wrote: I initially tried using Dishtv splitters with qualified success. On closer examination the bandpass between dish 1 and dish2 is different and neither actually calmed to pass the GPS frequencies. And indeed I had significantly different path losses. I wanted a better solution. I did a brief search and found the following. The results are much better and the price was very reasonable. My path losses appear to be balanced and generally agree within 1dB, with at least 10 SV reporting 39 - 49dB. The splitter I tried has a claimed bandwidth of 40 to 2400 MHz and a all ports power pass. Of course you have to have the adaptors from type N to type F and type F to type SMA. I was able to find all of those on Amazon and don't forget some type F terminators, they are hard to find in local box stores. Hope this helps some of the new guys, like myself, to get their labs up a little quicker. Computer Network Accessories, Inc. 5520 Burkhardt Road Dayton, Ohio 45431 Web: www.CNAweb.com http://www.cnaweb.com/ Email: sa...@cnaweb.com Phone: 937-258-2708 - Fax: 937-258-2743 Product NamePart No.QuantityItem PriceTotal Price4 Way 2GHz Splitter w/ DC Pass72-2443$4.10$12.30 Subtotal:$12.30Shipping Handling:$7.35Tax:$0.00 -- Order Total:$19.65 -- S. Cash Olsen KD5SSJ ARRL Technical Specialist ___ 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] Jackson labs fury gpsdo with docxo for sale
According to the brochure, they are only $750 new. Or am I missing something here? R On 26 June 2015 at 03:30, Mark Spencer m...@alignedsolutions.com wrote: Hi I'm wondering if there is any interest in my Jackson labs fury (desktop version) with the docxo option. I purchased it new from Jackson Labs in 2012. It has sat on a shelf powered up for almost the entire time I have owned it. I've been very happy with the unit but I haven't made much use of it over the last year and don't foresee any future need for it. I'm not in a huge hurry to sell it but I would be looking for 1,250 USD plus insured shipping from Canada (also the buyer would need to pay any taxes or duties that are payable by the buyer.) I would include the power supply it shipped with from Jackson labs. I'm also looking at selling it via some other channels as well so it may be gone soon. Please contact me off list if you are interested in pursuing this. I'm happy to send photos and provide more details to an interested party. Thanks Mark Spencer m...@alignedsolutions.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. ___ 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] PCI-E Serial Card For Windows NTP?
Hi I have had no problem with a variety of PIC serial cards. I’ve got a few from maybe six different outfits. They run up to at least 115.2K baud. The multi port versions will do that on all ports at one time. They are far more dependable than their USB counterparts. I’ve run them under XP, Vista, Win 7, Linux and Free BSD. They don’t seen to have problems under either the 32 or 64 bit versions. I would get it from a vendor who’s name you recognize. Not so much because it will be a better part. Only so that tracking down the Windows 10 drivers (or which ever version we all will be on) is a bit easier. Bob On Jun 25, 2015, at 1:41 AM, Ed Armstrong eds_equipm...@verizon.net wrote: Hi, I'm still pursuing setting up a fairly accurate NTP server connected to my Nortel/Trimble GPSTM. So far I've been playing with a Raspberry Pi 2, and have made fairly good progress using a bunch of tweaks detailed by another member of this list. However, it has been noted that the Raspberry Pi has some limitations for this purpose, not the least of which is having a USB connected ethernet port. Consequently I am also looking at some other options. The GPSTM and the Raspberry Pi will be sharing a shelf with my server, which is running a Core i7-3770 @ 3.4Ghz and a 64-bit version of Windows 7 Ultimate. This machine is typically running at about 10 to 20% CPU usage, and it is extremely rare for the CPU usage to exceed 50%. It is also equipped with an Intel gigabit ethernet port, connected by PCI express bus. I expect this may perform a little better than the pi's 100Mb card which is connected by USB. I also suspect that the i7 will do a bit better in terms of interrupt latency. There is a driver available for Windows 7 which allows use of the DCD pin on a serial port for PPS. Sadly, this machines motherboard does not have a serial port, nor a parallel port. Not even a header for one. And this leads to my question. I am considering adding a PCI express serial port card to this machine, but I don't know how well they perform for this application. There are quite a few different cards available, ranging in cost from under $10 to over $50. I am wondering how well these cards work for this application in general, and if there are some cards which will work well and some which will work poorly or not at all. And of course, if there is major variation between the cards, I would like to know how to pick one which will work well. I do have a little experience with parallel port add on cards, as I run a CNC milling machine which uses the parallel port to control the machine. Most of the parallel add-on card you can buy work fine for a printer, but will not work at all for sending pulses to the CNC machine. Only a very few cards are full function parallel ports, and they are pricey. Before I waste $8 on a cheap serial port card, I want to make sure I'm not looking at the same situation. If it matters, I'm planning on a dual-port card. Thanks 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.
Re: [time-nuts] PCI-E Serial Card For Windows NTP?
Trying not to go offtopic. If there are specific lists for this type of nuttery, contact me off list - would love to learn and discuss more. That said - if you're going to test the impact on latency for interrupt coalescing, I'd suggest using sockperf ping pong test: https://github.com/mellanox/sockperf Should reveal a bit more than a simple icmp ping test can. Use the --pps flag to test a variety of packet rates. Should help show the effect of coalescing. - Brian On Thu, Jun 25, 2015 at 13:40 Hal Murray hmur...@megapathdsl.net wrote: I know next-to-nothing about Windows. Serial ports are pretty standard. I'd get the cheapest card. I'd probably pay a bit more for a second port. It might be handy tomorrow. One difference between chips is the depth of the FIFO. PCI card now come in two heights. Make sure you get the right one. The short ones don't have room for a second connector. (Some cards come with two face plates. You can swap in/out the other one if you can use a screwdriver.) The other thing to keep an eye on is interrupts from the Gigabit ethernet. With a lot of short packets, you can get in trouble spending all your CPU time in the interrupt handler. Some hardware is setup to batch interrupts. The idea is to delay an interrupt for a while in hopes that more packets will arrive and get processed as a batch. You may want to turn that off. It's a tradeoff between latency and CPU usage. You may be able to measure it with something like ping. -- 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. ___ 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.
