[time-nuts] Symmetricom 5120A Needs a Home
I have a lightly used Symmetricom 5120A that I'd like to donate to a University that could make use of it in research or education. I'm in Boulder Colorado so I'd prefer a US school to simplify shipping. I only used it on one short project and haven't fired it up in years (I am clearly not much of a time-nut). I'd like to start the process of finding a good home for it. I'm not interested in selling it to individuals. Any suggestions for a home will be appreciated. Thanks, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] 74ACT160 100MHz divide by 10
I haven't been following all the posts on this topic and apologize if repeating someone else's observations. There are dip versions of the 74ACT160N that will do 100MHz over temperature depending on the manufacturer. The MC74act160N is a dip part available from Ebay at 10 for $10.00. The package is obsolete so unless you plan to buy safety stock it isn't for production. https://www.ebay.com/i/113374007747?chn=ps I resurrected my old Motorola FACT data book and: At 5V it is rated to 120MHz with 50p loading at 25C. It is rated at 100MHz over temperature. Since the absolute max voltage is 7 volts you could run it at 6 volts at even higher clock speeds. The MC74AC160N will not run at 100MHz over temperature and isn't available on ebay. I'd be curious to know how warm the part gets at those frequencies. Bob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] A simple sampling DMTD
Timing Solutions Corp had several products that might be of interest. Designed around 20 years ago. The TSC5110 was mixer based. The TSC5120 and successors were A/D based. The block diagram in the TSC52120A datasheet may be of interest: https://www.axiomtest.com/documents/models/MicroSemi%205120A%20DataSheet.pdf In the TSC5120A manual, Appendix B has some theory: https://deki.mpifr-bonn.mpg.de/@api/deki/files/4701/=TSC-5120A-MAN-Rev-G.pdf For you history buffs, Timing Solutions was bought by Symmetricom, which was bought by Microsemi which was bought by Microchip. The location and many of the key employees at TSC have remained despite all the ownership changes. Cheers, Bob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] OCXO Support Board - PCB Source
It is nice to see PCBway mentioned. I've used PCBway for years. With over 30 designs, I've never been disappointed. Their best feature, aside from pricing, is the ease of getting quotes. They don't care about the number of holes in the board. Board dimensions, thickness and volume are the main price determinants. I have done 6 layers with no problem. No one likes paying for shipping but you do get actual one week delivery to Colorado for two layer boards. Bob Am 13.05.20 um 13:35 schrieb Bill Notfaded: > I've been trying to find a base PCB design to use too. In the interim I > bought some boards from Gerry Sweeney that sells them for HP5313x frequency > counter OCXO upgrades and supports different footprints. Open source > design is even better. OSHpark is great. Please post it! Here it is: < http://www.hoffmann-hochfrequenz.de/downloads/ocxo_carrierV2_pack.zip > These are the Gerber files as used by PCBway to produce my boards. 2 buglets: - the 2 mounting screws for the 10811 should be slightly bigger. Drill as needed - Unless the oscillator delivers only a small signal, the 2 emitter capacitors should each get 22 Ohms in series to adjust gain. This will be addressed in V3. Circuits are included, comments and small change requests are welcome, could be done shortly thanks COV19. cheers, Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Alfred Loomis - an early time nut
Thanks to all who replied. Book on order. Given all his accomplishments, he must have been a "Renaissance Time_Nut"! Bob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Alfred Loomis - an early time nut
Does anyone know about Alfred Loomis and his early precision time measurements? According to the article in the link below, he was also involved in WWII radar and the creation of Loran. http://www.ob-ultrasound.net/loomis.html bob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] How the West is Losing the Timing and Navigation War
This might be of interest to Time-Nuts. The reference to Russian Loran is interesting. https://rntfnd.org/2020/02/03/how-the-west-is-losing-the-navigation-and-timing-war-navigation-news/ ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] eLoran
I meant to add because I designed the first version, I'm excited to see it coming back to life. Of course most of the original hardware that controlled the timing of the signals has been replaced by an FPGA... Bob Dave, The van is at Timing Solutions -> Symmetricom -> Microsemi -> Microchip Technology. I designed the hardware for the first incarnation of eLoran which was funded by the FAA as a backup for GPS. Bob Hi Bob- Is the van still open to viewing? I'm in Boulder as well, must be at NIST? Dave On Sat, Feb 8, 2020 at 2:07 PM Bob Martin wrote: > On Friday I was given a tour of a van that is > being outfitted to monitor eLoran signals. > Pretty exciting. > > Bob > Boulder,CO > > ___ > time-nuts mailing list -- time-nuts at lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] eLoran
Dave, The van is at Timing Solutions -> Symmetricom -> Microsemi -> Microchip Technology. I designed the hardware for the first incarnation of eLoran which was funded by the FAA as a backup for GPS. Bob Hi Bob- Is the van still open to viewing? I'm in Boulder as well, must be at NIST? Dave On Sat, Feb 8, 2020 at 2:07 PM Bob Martin wrote: > On Friday I was given a tour of a van that is > being outfitted to monitor eLoran signals. > Pretty exciting. > > Bob > Boulder,CO > > ___ > time-nuts mailing list -- time-nuts at lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] eLoran
On Friday I was given a tour of a van that is being outfitted to monitor eLoran signals. Pretty exciting. Bob Boulder,CO ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)
There is a reason dictionaries supply multiple definitions to words and it's not surprising that some engineer or scientist chose the most common meaning of decimate in coining the name decimation filter. I must admit it bugs me as well when the decimate is equated with slaughter. The meaning of words can evolve over time. Washington DC had (has?) a radio station called WGAY back in the seventies. The the meaning of the word gay evolved since those call letters were first assigned. Interestingly the station formats evolved with the word. http://beautifulmusicradio.blogspot.com/2013/01/wgay-and-wqmr-washingtons-quality-music.html Back in those same seventies, I was working for an army lab (Harry Diamond Labs) as a summer student. I saw a picture in a lab supply catalog of a (ein) stein of beer. I tore it out and taped it over a picture off Albert Einstein that a German physicist, Howard Brandt, had on the wall over his desk. This was a bad idea. Howard was so incensed that he called the whole department together, hauled out the Websters Unabridged Dictionary, and forced me to read the definition of the word philistine in front of the group. Fortunately, there were many entries under the word and I chose "a native of Philistia" to read out loud. The moral is words can have many meanings and, more importantly, don't make fun of Einstein around German Physicists. Bob Martin On 1/10/2019 6:58 AM, Tim Shoppa wrote: This is not misuse. Everyone in signal processing knows what decimation means in this context. I pulled out one of my older signal processing books - Gold and Rader, "Digital Processing Of Signals", 1969 - and Decimation is used in several places exactly as we use it today. I looked in some of my non-digital signal processing and older books, like MIT Rad Lab series, and don't see the term used, but I know that I heard old-timers using decimation used in automatic analog signal processing especially with regard to "zooming out" on a spectrum analyzer or pinball-style pulse-height analyzer (often the knobs gave you only factors of ten). Tim N3QE On Thu, Jan 10, 2019 at 7:02 AM Peter Vince wrote: In his comment below, Mark has used the word "decimate". There is much debate about what this word means (presently, and/or in the past), but common explanations refer back to Roman times when they apparently killed one person in ten as a punishment, and similarly "tithes" - or taxes, where one in ten was taken. Now OK, you can argue this until the cows come home, but the result is that the meaning isn't crystal clear, and particularly on a technical forum where precision is paramount, and the entire reason we are here, I believe accuracy and clarity of expression is also important. In this instance, I believe "truncate" would be a better word. :-) Regards, Peter Vince On Wed, 9 Jan 2019 at 23:56, Mark Sims wrote: ... And as far as decimating the TICC output values in firmware... please don't. Let the user decimate the values if they want to. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Last Oscillator to give away
Time_Nuts, This is basically the last oscillator to give away. It was slated for Italy but the postage and VAT were more than its perceived worth. Osc8 OXCO MTI Milliren 250-0700-B 5.0MHz sine Mounted in cast metal box with iso-amp to raise output level. It is on a board with an unloaded SMA for tuning. I used it with the Symmetricom 5120 for testing Distribution amp noise. The link to the image is below: https://app.box.com/s/hq22jbe3jdfzhfqnot1hxcvjqwdooj6m I'd prefer it goes someone who will use it. So, if you want it, please tell me how you plan to incorporate it into your timing system. Please be sure to contact me off-list to spare the group and the moderator from unwanted messages. My email is aph...@comcast.net Best, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] OCXO Board
Bert, That looks like a useful board. Certainly some of the oscillators I'm giving away would fit nicely on it. Since it looks like a two layer board, a quick check at pcbway.com puts the cost at $.79 apiece at the 100 quantity exclusive of shipping. Best, Bob Martin On 10/26/2018 4:17 AM, ew via time-nuts wrote: There recently was a request for an OCXO board. I did a layout, see attached and had Corby do his usual QC test. If some one is interested to make boards and maybe sell to other time nuts please contact me off list and I will get you code and possible suppliers. Board does not have an amp but could be added, if so, please advise, what should be added. Regardless what the direct output will remain Bert Kehren ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Residual Oscillators
Time_Nuts, Most of the oscillators have arrived at their new homes. There are still a few left including some nice ones. OSC4 OCXO Symmetricom STP2640 LF 10MHz sine. This was pulled off a board and there is no data on it. I have marked the pinout on the bottom (Vasco please note this). Osc6 OCXO Morion MV200 10MHz sine Attached to mixer based locking circuitry Designed to lock to external 10MHz reference. If you want it, you will need to show how you plan to use it appropriately. Osc8 OXCO MTI Milliren 250-0700-B 5.0MHz sine Mounted in cast Bud box with iso-amp to raise output level. Osc11 OCXO MTI Milliren 220-0199 32MHz square quant = 2 Boards Note the revised specs: Output of board is 32MHz square wave 2.5V into 50 ohms. These "Lockoscillator" boards were designed to lock automatically to 5 or 10MHz reference. Locking is mixer/integrator based. Used in 5MHz steered DDS's. If you want one you will need to have be explicit regarding your application. Osc 12 OXCO MTI Milliren 220-0199 32.0MHz square 2 remaining Osc14 OXCO MTI Milliren 220-0224 77.76MHz square 1/2 SONET OC-3 frequency Osc15 VCXO Vectron 155.52MHz PECL out - SONET OC-3 frequency The link to images, along with a few datasheets is below: https://app.box.com/s/hq22jbe3jdfzhfqnot1hxcvjqwdooj6m I'd prefer they to go to those who will use them. So, if you want one, please tell me how you plan to incorporate it into your timing system. Please be sure to contact me off-list to spare the group and the moderator from unwanted messages. My email is aph...@comcast.net Best, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscillators Away
Time-Nuts, I've processed all the oscillator requests and have made decisions. In addition to the huge demand for the Rubidium's, many people asked for 10MHz OCXOs. I'm sorry if you wanted and didn't get one. I tried to base things on the stated need for an oscillator while roughly factoring in the quality of the oscillator for the application. Thank you for all the interesting stories about your applications. I'll be sending emails to recipients in the next day or so. There are still a few available and some recipients may not reply. I'll create a new list from the residuals and post it. It seems fair to tell you who got the Rubidium's and why. The PRS10B will go to Attila Kinali. I enjoy his posts and his proposed use for it. Having worked with scientists for a good part of my career, I appreciate those who like to make measurements. I also support those starting out in their fields. Maybe he will change his major. The other Rubidium has a more interesting "trajectory". It is loaned to Tom Van Baak who will help fly it under a balloon in his quest to again demponstrate part of the General Theory of Relativity. It then goes to Mark Simms who wants to add support for it to Lady Heather. After that Tom will give it away to one of you. As usual, if you want to respond to me personally, send your email to aph...@comcast.net Best, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscillators to give away
Time-Nuts, To those who got a step attenuator or RF splitter, they are finally on their way to you. I just found a Wavetek 5010A step attenuator if anyone is interested... So far I have only 16 requests for oscillators. 15 of those were for one or both of the two Rubidiums. Clearly the odds aren't good for you to get one but I do thank you for your descriptions of your proposed applications - some are quite unique. Would anyone like a nice OCXO? Best, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscillators away
Time-Nuts, If you have had a chance to review the list of oscillators I'm giving away, please send me your requests. The link to images, along with a few datasheets is below: https://app.box.com/s/hq22jbe3jdfzhfqnot1hxcvjqwdooj6m Note that there are two pages in the Box.com folder. I'm willing to part with them, one or two to a customer, in return for the cost of shipping. I'd prefer they to go to those who will use them. So, if you want one, please tell me how you plan to incorporate it into your timing system. Please be sure to contact me off-list to spare the group and the moderator from unwanted messages. My email is aph...@comcast.net I plan to collect requests for a while before making any decisions. I'll acknowledge all requests. Thanks, Bob Martin Oscillator List Osc 1 Efratom EMXO Series Sub-Miniature Military Quartz Crystal Oscillator Old Unit 10MHz sine out - data sheet in Box link Osc2 Efratom EMXO Series Sub-Miniature Military Quartz Crystal Oscillator Old Unit 10.23MHz sine out - data sheet in Box link. Osc3 OCXO Morion MV200 10MHz sine OSC4 OCXO Symmetricom STP2640 LF 10MHz sine Osc5 OCXO Unknown CQE 0140/0020 DOC3098 10MHz sine Size like Milliren 250 series Osc6 OCXO Morion MV200 10MHz sine Attached to mixer based locking circuitry Designed to lock to external reference. If you want it, you will need to show how you plan to use it appropriately. Osc7 OXCO Morion MV83M 5.0MHz sine Mounted in box with regulator and SMA output Osc8 OXCO MTI Milliren 250-0700-B 5.0MHz sine Mounted in cast Bud box with iso-amp to raise output level. Osc9 OXCO MTI Milliren 240-0536-C 16.0MHz square Osc10 OXCO MTI Milliren 240-0551-C 16.0MHz square Osc11 OCXO MTI Milliren 220-0199 32MHz square quant = 4 Output of board is 16MHz square wave 3V into 50 ohms. "Lockoscillator" boards designed to lock automatically to 5 or 10MHz reference. Locking is mixer/integrator based. Used in 5MHz steered DDS's. If you want one you will need to have be explicit regarding your application. Osc 12 OXCO MTI Milliren 220-0199 32.0MHz square quant. = 4 Osc13 OXCO MTI-Milliren 220-0199 32MHz doubled to 64.0MHz Mounted in box with mixer doubler, filters and sine to square wave converter. Osc14 OXCO MTI Milliren 220-0224 77.76MHz square Osc15 VCXO Vectron 155.52MHz PECL out Osc16 TCXO Vectron TC-210-DFC-S5711 100MHz PECL out Data sheet in Box link. Osc17 Symmetricom SA.35m Rubidium 10MHz sine Verified sine out Osc18 Stanford Research PRS10B Rubidium 10MHz sine Verified sine out and PPS Some items were dumpster dived including Osc4, Osc17 and Osc18. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscillators
Time-Nuts, It has been pointed out that I've been a bit draconoian. If you will be out of touch from the middle of next week on and are interested in oscillators, feel free to enter your requests now. Also let me know when you will be back in contact. Lastly, I thought I'd given all the step attenuators away but one of the individuals who responded hasn't gotten back to me so I have one available. let me know why you want it and it is yours. Best, Bob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscillators
Time-Nuts, I'm already getting requests from people who can't read! Please don't contact me until everyone has a chance to process the list of oscillators. Cheers Bob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscillators away
Time-Nuts, I have a number of oscillators to give away. The link to images, along with a few datasheets is below: https://app.box.com/s/hq22jbe3jdfzhfqnot1hxcvjqwdooj6m Note that there are two pages in the Box.com folder. I'm willing to part with them, one or two to a customer, in return for the cost of shipping. For myself, I'd prefer they to go to those who will use them. So, if you want one, please tell me how you plan to incorporate it into your timing system. If you have questions about individual oscillators please send then to the group because the answers can then be shared. The moderator can decide whether this is a viable process. Other than the moderator, please DO NOT not contact me directly for now. In a week or so I'll send a message to the group to begin the request process. This should allow everyone time to consider their needs and possibilities. Some of the devices are valuable and I may share your requests with the group or individuals in the group as a sanity check for your request. Again, please don't contact me directly until everyone has a chance to review the list and I send the post to begin. The selection process will be off-list. Thanks, Bob Martin Oscillator List Osc 1 Efratom EMXO Series Sub-Miniature Military Quartz Crystal Oscillator Old Unit 10MHz sine out - data sheet in Box link Osc2 Efratom EMXO Series Sub-Miniature Military Quartz Crystal Oscillator Old Unit 10.23MHz sine out - data sheet in Box link. Osc3 OCXO Morion MV200 10MHz sine OSC4 OCXO Symmetricom STP2640 LF 10MHz sine Osc5 OCXO Unknown CQE 0140/0020 DOC3098 10MHz sine Size like Milliren 250 series Osc6 OCXO Morion MV200 10MHz sine Attached to mixer based locking circuitry Designed to lock to external reference. If you want it, you will need to show how you plan to use it appropriately. Osc7 OXCO Morion MV83M 5.0MHz sine Mounted in box with regulator and SMA output Osc8 OXCO MTI Milliren 250-0700-B 5.0MHz sine Mounted in cast Bud box with iso-amp to raise output level. Osc9 OXCO MTI Milliren 240-0536-C 16.0MHz square Osc10 OXCO MTI Milliren 240-0551-C 16.0MHz square Osc11 OCXO MTI Milliren 220-0199 32MHz square quant = 4 Output of board is 16MHz square wave 3V into 50 ohms. "Lockoscillator" boards designed to lock automatically to 5 or 10MHz reference. Locking is mixer/integrator based. Used in 5MHz steered DDS's. If you want one you will need to have be explicit regarding your application. Osc 12 OXCO MTI Milliren 220-0199 32.0MHz square quant. = 4 Osc13 OXCO MTI-Milliren 220-0199 32MHz doubled to 64.0MHz Mounted in box with mixer doubler, filters and sine to square wave converter. Osc14 OXCO MTI Milliren 220-0224 77.76MHz square Osc15 VCXO Vectron 155.52MHz PECL out Osc16 TCXO Vectron TC-210-DFC-S5711 100MHz PECL out Data sheet in Box link. Osc17 Symmetricom SA.35m Rubidium 10MHz sine Verified sine out Osc18 Stanford Research PRS10B Rubidium 10MHz sine Verified sine out and PPS Some items were dumpster dived including Osc4, Osc17 and Osc18. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Fifth Batch to Give Away
Time-Nuts, I keep finding more stuff to give away. Link to View these items: https://app.box.com/s/vnajhrt14jw5rxnqwdtuvrs07qbzikj3 Item 20 Two Mini-Circuits splitters 1:2 ZFSC-2-1W 1-750MHz 1:3 ZFSC-3-1-S+ 1-500MHz Item 21 Four step Attenuators SMA 1-10dB Alan 50V10 series One piece/Time-Nut who best shows me they really can use it. Just for the cost of shipping. To save the moderator angst, please contact me off-list. Cheers, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Dealing with Oscillators
Time-Nuts, Thanks for all the help in taking my stuff. If you haven't heard from me directly, all the boards in the four batches have been spoken for. I do have some oscillators which I suspect will be in high demand. I'll list them and provide photographs soon. I have received a number of helpful suggestion on how to disperse them. This was my favorite courtesy Bill Hawkins: "Quickly, there was a man named Larry Ware who ran a Home for Wayward Test Equipment. He established what came to be called "The Rules of Ware" for selling things. Rather than first reply, he offered stuff to people with the best story for how they would use it." I'd like to run with that. I also think I will try and spread them out to as many people as possible. I'll also wait a week before deciding so that you don't have to feel in a hurry to make your requests. Does this sound like a reasonable plan? As usual, unless you are Moses with tablets or have a Larry Ware story to share, let's keep comments off the main list out of respect for the moderator. Thanks, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Fourth Batch to Give Away
Time-Nuts, This is the last batch of hardware excluding oscillators. Link to pictures of boards here: https://app.box.com/s/mhb3qn1c13x5lggtvd2r6p7feoq76ify Item 7: Found one more 1x6 RF Distribution amplifier. Used to send 5 or 10MHz around and about. Will deliver 1VRMS into 50 ohms with Zout = 50 ohms. Item 10: Last chance at these supplies. Have three left. These boards powered a TSC hot-swap chassis. The input was 24V from AC and batteries. Each board has three converters providing +-12V and +5V. I believe they were 100 W each. Item 15: A PPS splitter. 3V into 50ohms back terminated. 50 ohm TTL level input. Item 16: 5MHz sine to 10MHz sine mixer based doubler. Two sine outputs, has low Q toroid band pass and 2 notch filters at 5 and 20MHz. Need spectrum analyzer to tune filters. Item 17 I have three of these analog mixer boards. Buffered inputs to mixer and integrator to tune an oscillator. Oscillator footprint is for Morion MV200. Nice for locking A to B. There are 2 buffered outputs. Item 18: Dual low phase noise iso amp 50ohm out will do 1VRMS into 50 ohms. Prefer that it goes to someone who can measure phase noise below -170. I'd like to know it's measured phase noise. Item 19: 1x2 low phase noise iso amp. I have three of these boards. Two buffered outputs, 50 ohm out will do 1VRMS into 50 ohms. Prefer that they go to those who can measure phase noise below -170. I'd like to know the measured phase noise. If multiple people want the same item, the one who best convinces me they will incorporate it into their setup gets it for the cost of shipping. To save the moderator angst, please contact me off-list. Cheers, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Third Batch to Give Away
Time-Nuts, I have a few more things to unload: Link here: https://app.box.com/s/nhgj3x4gcm7pn5xufh541xao8x0io366 Item 5: I still have one left of item 5. This was part of a SASSM unit that provided 10MHz sine and Square wave, IRIG, and PPS. Item 10: Got rid of one, have three left. These boards powered a TSC hot-swap chassis. The input was 24V from AC and batteries. Each board has three converters providing +-12V and +5V. I believe they were 100 W each. Item 13: A GPS antenna AeroAntenna AT2775-42SYO-TNCF-00-RG-41-NM. Datasheet is part of link. This is a 5-18V unit. Not tested by me but looks new. Item 14: Two Novatel GPS receivers. SSII-5-ICPT-19. I have no idea if these old timing receivers are of interest to anyone. If multiple people want the same item, the one who best convinces me they will incorporate it into their setup gets it for the cost of shipping. To save the moderator angst, please contact me off-list. Cheers, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Efratom Oscillators
Anyone, I have two Efratom EMXO Series Sub-miniature Quartz Oscillators I'd like to test before parting with them. Does anyone have a datasheet or pinout and supply voltages? They supposedly have pins for oven power, oscillator power and TTL power! Thanks, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Free Stuff - Moving Forward
Bob, I'm looking for suggestions on how to disperse the stuff fairly. Thanks, Bob On 9/19/2018 2:42 PM, Bob Albert via time-nuts wrote: Bob, I am interested in the XOs. What do you have, and how much to get it to me in Los Angeles? Bob On Wednesday, September 19, 2018, 1:31:48 PM PDT, Bob Martin wrote: Time-Nuts, Thanks to those who took the various signal distribution boards and other stuff. You took almost everything and it's boxed up and ready to ship. I'm now looking at higher value items such as TCXO's, OCXO's (and better) to give away. My dilemma is that, while I'm happy to let go of the stuff, I don't want it ending up on ebay or to be sold. I really want it to be used by the recipients. Does anyone have any suggestions on how to deal with this? Out of respect for the moderator, please reply directly to me. Best, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. | | Virus-free. www.avast.com | ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Free Stuff - Moving Forward
Time-Nuts, Thanks to those who took the various signal distribution boards and other stuff. You took almost everything and it's boxed up and ready to ship. I'm now looking at higher value items such as TCXO's, OCXO's (and better) to give away. My dilemma is that, while I'm happy to let go of the stuff, I don't want it ending up on ebay or to be sold. I really want it to be used by the recipients. Does anyone have any suggestions on how to deal with this? Out of respect for the moderator, please reply directly to me. Best, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Free Stuff Second Batch
Time-Nuts, I've unloaded some items and have a few more to through into the pot: Link to Pictures of Items: https://app.box.com/s/dh313geiuavi4ddjr14i5yddmjnew8pg Item 4: A 1:9 pulse distribution amplifier. Outputs 5V into 50 ohms. Not super low skew but certainly fine for most PPS distribution. I'm really surprised no one wanted this since some much conversation is about PPS. Item 5: A multi distribution amplifier 1:4 sine, 1:4 pulse, 1:4 IRIG. Was part of an NTP Server. I have two of these left (out of three) to give away. Item 6: Time Code Translator Main Board from NASA Deep Space Upgrade. Has a 100MHz PECL oscillator with distribution. I believe it will lock to a 100MHz Fiber Optic signal in case someone wants to experiment with FO distribution. Item 7 A 1:6 RF distribution amplifier built for USNO. Item 8 Parts from a TSC5110 Time Interval Analyzer. The top item is a dual Zero Crossing Detector Assembly. The lower item is an interface board. One of you may have this unit which is discontinued so the spares are yours if you want them. Item 9 An interesting part for those of you who are "connected". They are Lantronix XPort Ethernet to RS232 converters. As you can see there are four to give away. Item 10 These are intermediate bus converters. +-12 and +5 out. 24V in. About 100W each. May be useful to someone. I have three of them. These aren't tested but should work. The heat sinks at the bottom are "oring" diodes. Item 11 These are digital delay lines controlled by DIP switches. The delay line is a Maxim DS1023-100. Max delay is 250ns. There are two of them. Item 12 A transformer isolator for rf signals. If multiple people want the same item, the one who best convinces me they will incorporate it into their setup gets it for the cost of shipping. To save the moderator angst, please contact me off-list. Cheers, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Free Stuff
Time-Nuts, There were no takers on helping me sort through stuff I'd like to give away so I've begun the task myself. so far I've given away some SX28AC IC's and an SX-Key programmer. I have 8 distribution boards to pass on. Link to Pictures of Items: https://app.box.com/s/x1ukea5zx91fqb149t6odjgo0nmbodm2 Item1: A SpectraDynamics 5,10 MHz Distribution Amplifier Model HPCA-10 - for those who like transistors in their dist. amps. Item2: A 1:15 sine wave distribution amplifier. Very (very) similar to a Symmetricom 4036. Item3: A 1:8 sine wave distribution amplifier - part of a 2 input fault switch. Item4: A 1:9 pulse distribution amplifier. Outputs 5V into 50 ohms. Not super low skew. Item5: A multi distribution amplifier 1:4 sine, 1:4 pulse, 1:4 IRIG. Was part of an NTP Server. I have three of these to give away. Item6: Time Code Translator Main Board from NASA Deep Space Upgrade. Has a 100MHz PECL oscillator with distribution. I believe it will lock to a 100MHz Fiber Optic signal in case someone wants to experiment with FO distribution. All the items work except for Item6 which I can't test. I can help you get them powered up integrated into your timing systems. If multiple people want the same item, the one who best convinces me they will incorporate it into their setup gets it for the cost of shipping. To save the moderator angst, please contact me off-list. Cheers, Bob Martin ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Can eloran Backup GPS?
Courtesy a quick internet search: http://insidegnss.com/south-korea-developing-an-eloran-network-to-protect-ships-from-cyber-attacks/ https://rntfnd.org/wp-content/uploads/Korea-Jamming-Chart.jpg There was lots of stuff like the above. It apparently just won't stay dead. It seems one doesn't need a cataclysm - just a bad actor like North Korea. Bob Martin On 9/9/2018 9:34 AM, paul swed wrote: The correction stream is transmitted in the eLORAN signal and does require some form of reference site to transmitter connection. Just like GPS and lightspeed use RF to send corrections to the satellites. Loran C also did the same adjustments from a control site. But I am hearing nothing about eLORAN these days. It does not show up very often anymore in some of the navigation publications. Regards Paul WB8TSL On Sun, Sep 9, 2018 at 11:20 AM, Poul-Henning Kamp wrote: In message <3d2ae1be-927a-574a-e7f0-c7d2d289d...@earthlink.net>, jimlux writes: On 9/8/18 4:52 PM, paul swed wrote: I suppose you could have a low rate network (i.e. not "the internet") and for the most part, the propagation corrections (whether using 60kHz, Loran, Omega, or GPS) can be done with "climatology" - time of day and time of year. Transmitting real-time corrections is not the problem, coming up with them in the first place is. One of the reasons eLoran failed to go anywhere in europe is that tests showed that modern container freighters are big enough to 'relevantly disturb Loran-C'. Nobody has a clue how you could possibly measure the necessary real-time corrections for narrow and heavily trafficked straits like as The English Channel, The Great Belt etc. For big/expensive boats, INS/IMU is the goto-solution, at around $20-50k a piece, depending on specs. In difference from anything relying on radio signals from people you can maybe trust some of the time, INS/IMU is entirely on-board, which can lower your insurance premiums if you sail certain parts of the world. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/ listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Lars GPSDO on EEVblog
Charles, Attached is another way to do it. A higher charging voltage increases capacitor voltage linearity over the range of the ADC making curve compensation easier. The bus switch has a very low on resistance to pretty much discharge the cap. The design is pretty old - I'm sure there are better parts available now. I believe there was also a calibration cycle that occurred fairly often which is why U21 looks so busy. Cheers, Bob Martin On 9/8/2018 8:17 PM, Jim Harman wrote: Charles wrote, According to my tests, the B-C junction of a high-quality 2N3904 has about 50pA of leakage at 20vDC reverse voltage. That's good to know, but the problem I had with this circuit was with the forward current at a low forward voltage. With this phase detector, the HC4046 makes a 0 to 1 usec pulse representing the time difference between the 1 pps from the GPS and the 1 MHz derived from the OCXO. This charges the capacitor to a voltage proportional to the width of the pulse, the ADC measures the capacitor voltage, and the cap discharges through the 1 Meg resistor during the rest of the second. When the HC4046 output goes low at the end of the pulse, the voltage on the other side of the 1N5711 diode goes down to about 0.4 V. With a 1N4148 or similar diode instead of the transistor, the forward current after the capacitor is mostly discharged through the 1 meg resistor is enough to prevent the capacitor from discharging all the way and the minimum voltage at the ADC is about 0.3 V. or about 120 counts on the ADC. I was able to get this below 90 counts by using the transistor. It might be possible to reduce the 1 Meg resistor, but then we risk significantly discharging the capacitor in the short time between the end of the pulse and the A/D reading. I would certainly be interested in any suggestions on improving this circuit. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Can eloran Backup GPS?
Bob, That seems pretty conclusive to me but wait there's more.. By adding a letter to the name they are attempting to address the very issue you've raised. https://rntfnd.org/wp-content/uploads/eDLoran-Reelektronica-Paper.pdf I'm sure after a few more prefix letters are added to Loran it will work for everyone! Time for a new house to flip or dead horse to flog, Bob Martin On 9/8/2018 2:44 PM, Bob kb8tq wrote: Hi The differential approach to eLoran involves running two local receivers. You look at the time of arrival on one and use it to “calibrate" the time of arrival on the other. Put another way - you look at the difference between the two arrival times. They can both “wander” over a 250 ns range, as long as they stay within 50 ns of each other they meet the “differential spec”. For disciplining a local reference, you really need an absolute number. The fact that both are wandering over a pretty big range *does* matter if you are looking at a stable local source (and trying to make it more stable). What would / does work is having a very accurate standard at one of the locations and using the difference measure to “distribute” that source. That gets into bandwidth. Since the difference information is *very* local, there really isn’t a practical way to distribute it on the eLoran signal. As you pile on more correction stations, your data bandwidth goes up. There are a very limited number of bits available on the eLoran signal. Another way to look at it: If you have a standard sitting in your basement, and don’t have a buddy in town with a better standard. Does a difference measure to his house do you any good? Bob On Sep 8, 2018, at 2:58 PM, Bob Martin wrote: Bob, I believe that information is transmitted with the eloran signal. Way back when, I remember there was an added pulse called the LDC pulse. I had to modify that pulse with each transmission based on an input to the transmit timing unit from the computer. I found the following on it: http://www-personal.umich.edu/~tmikulsk/loran/ref/eloran_ldc.pdf Also, the article referenced previously on The Great Britain system mentions that the differential corrections are sent on the LDC pulse. To be honest, I don't know if this addresses your "gotcha". Best, Bob Martin On 9/8/2018 12:38 PM, Bob kb8tq wrote: Hi The gotcha is the differential corrections. That’s not the way these systems are set up to work. They function with no external input other than the timing signal its self. Providing bandwidth to do correction signaling just isn’t part of the overall system design. If you wanted to use bandwidth, you would go with 1588. Then you have a backup and no fiddling with anything else. Indeed with an area wide 1588, you can do it all without even a GPS primary. Simply agree on a “something” as the master source. The man with one watch *always* knows what time it is …. The 250 ns "without correction" is the number that directly compares to the ~10 ns number for GPS. Stretch out the distances to “USA” sort of stuff and it does not improve things at all. Bob On Sep 8, 2018, at 1:40 PM, Bob Martin wrote: Bob, I agree that eloran needs to be analyzed with regard to it's usefulness for each potential application. You are also 100% correct that timing requirements get tighter and tighter as technology advances. In some ways the question isn't whether eloran can match GPS but rather would it suffice in a pinch were GPS to go down? I think the 50ns accuracy is actually "as received" not "as transmitted". The link below is an analysis of eloran in Great Britain. The receiver/transmitter distance was 300 miles. http://www.ursanav.com/wp-content/uploads/On-the-Uses-of-High-Accuracy-eLoran-Time-Frequency-and-Phase-2015.pdf I've attached a screen capture of one of the pages that compares eloran with GPS in case anyone is interested. This is where it appears that the 50ns is received as opposed to at the transmitter. Best, Bob Martin On 9/8/2018 9:35 AM, Bob kb8tq wrote: Hi I believe the 50 ns is the “as transmitted” signal from the tower. The “as received” signal after going through all the various gyrations is not that good on a ~1 second basis. One of the gotchas here is that we lump “systems” into one giant bag. That’s not a good way to analyze things. One system may be quite happy with 10 ms timing another may be happy with 10 us and yet another may die completely at 1 us and only run right at 100 ns. All of that is on a 2 second basis for CDMA (they time every other second). By far the biggest / baddest / most venerable system out the that uses GPS timing is the cell tower system. They started out back in the 80’s with a 10us max timing / 1 us running spec on CDMA. AFIK they were the first major system to adopt GPS time as their reference (rather than UTC). This worked out fine for a few decades wh
Re: [time-nuts] Can eloran Backup GPS?
Bob, I believe that information is transmitted with the eloran signal. Way back when, I remember there was an added pulse called the LDC pulse. I had to modify that pulse with each transmission based on an input to the transmit timing unit from the computer. I found the following on it: http://www-personal.umich.edu/~tmikulsk/loran/ref/eloran_ldc.pdf Also, the article referenced previously on The Great Britain system mentions that the differential corrections are sent on the LDC pulse. To be honest, I don't know if this addresses your "gotcha". Best, Bob Martin On 9/8/2018 12:38 PM, Bob kb8tq wrote: Hi The gotcha is the differential corrections. That’s not the way these systems are set up to work. They function with no external input other than the timing signal its self. Providing bandwidth to do correction signaling just isn’t part of the overall system design. If you wanted to use bandwidth, you would go with 1588. Then you have a backup and no fiddling with anything else. Indeed with an area wide 1588, you can do it all without even a GPS primary. Simply agree on a “something” as the master source. The man with one watch *always* knows what time it is …. The 250 ns "without correction" is the number that directly compares to the ~10 ns number for GPS. Stretch out the distances to “USA” sort of stuff and it does not improve things at all. Bob On Sep 8, 2018, at 1:40 PM, Bob Martin wrote: Bob, I agree that eloran needs to be analyzed with regard to it's usefulness for each potential application. You are also 100% correct that timing requirements get tighter and tighter as technology advances. In some ways the question isn't whether eloran can match GPS but rather would it suffice in a pinch were GPS to go down? I think the 50ns accuracy is actually "as received" not "as transmitted". The link below is an analysis of eloran in Great Britain. The receiver/transmitter distance was 300 miles. http://www.ursanav.com/wp-content/uploads/On-the-Uses-of-High-Accuracy-eLoran-Time-Frequency-and-Phase-2015.pdf I've attached a screen capture of one of the pages that compares eloran with GPS in case anyone is interested. This is where it appears that the 50ns is received as opposed to at the transmitter. Best, Bob Martin On 9/8/2018 9:35 AM, Bob kb8tq wrote: Hi I believe the 50 ns is the “as transmitted” signal from the tower. The “as received” signal after going through all the various gyrations is not that good on a ~1 second basis. One of the gotchas here is that we lump “systems” into one giant bag. That’s not a good way to analyze things. One system may be quite happy with 10 ms timing another may be happy with 10 us and yet another may die completely at 1 us and only run right at 100 ns. All of that is on a 2 second basis for CDMA (they time every other second). By far the biggest / baddest / most venerable system out the that uses GPS timing is the cell tower system. They started out back in the 80’s with a 10us max timing / 1 us running spec on CDMA. AFIK they were the first major system to adopt GPS time as their reference (rather than UTC). This worked out fine for a few decades while companies got a lot of towers built. People started using those systems and they became congested. Others started streaming video over them and they ran out of bandwidth. Upgrades followed. There have been a lot of them. Much of what we TimeNuts buy on the surplus market comes to us as a result of older systems being scrapped out. The latest set of upgrades does / will / is getting them into the sub 1 us range at the end of holdover. In normal operation they are spec’d at 100 ns worst case. To do that, you need a timing source in the roughly 10 ns range. No you don’t see those GPSDO’s on the surplus market. You will see them someday …. Again, they went this way a decade ago. Rolling that all back …. not at all easy. Are there other systems that have issues with sync? Of course there are. There also are a lot of instances where miss-configuration ( or junk implementation) is a much bigger issue. Sorting that all out requires a deep dive into the timing of each individual system / implementation. No two systems do things quite the same way. Unless you want to deal with the numbers and the implementation details, simply moaning and groaning isn’t going anywhere. Bob On Sep 8, 2018, at 3:23 AM, Hal Murray wrote: kb...@n1k.org said: You are not trying to run a cell system when checking your local oscillator against LORAN. The eLoran committee said 50 ns. Is that good enough for cell towers? Too bad it isn't up so we could collect some data. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/li
Re: [time-nuts] Lost GPS lock or 1PPS recently?
Here is an interesting and fairly recent link regarding eloran and telecom. https://rntfnd.org/2017/09/17/telecom-organization-recommends-eloran-system/ The report is here: https://access.atis.org/apps/group_public/download.php/36304/ATIS-095.pdf Page 11 has an nice table called "Time and phase end application synchronization requirements. It then really gets interesting starting on page 14. Again, I have no skin in this discussion other than it would be neat if that old gear I designed were to be resurrected! It does appear that poor old Loran has it's share of lovers and haters. I wonder if the numbers and assertions in this document truly reflect reality? As I said before, all this Time Nut debating over GPS dependency appears to be raging at many levels of government and industry. Best, Bob Martin On 9/7/2018 3:18 PM, Bob kb8tq wrote: Hi You are not trying to run a cell system when checking your local oscillator against LORAN. It’s two completely different things. The timing requirements of the modern systems are indeed way past what LORAN can deliver. We’re not talking about 1970’s state of the art anymore. You need a time source that is in the 10 ns range to keep this stuff running. Multiple microseconds of error in your timing source aren’t good enough for what they have up and are rolling out. Full end of holdover spec on many of them is below 2 microseconds. Normal operation is under 100 ns. Give the cell outfits another couple years and that’s all they will have on the air. Bob On Sep 6, 2018, at 9:08 PM, Scott McGrath wrote: As to eLORAN, you can deny positioning but maintain timing service simply by modifying the GRI and since eLORAN is software based thats not a difficult change. Navigation receivers go into fail but timing receivers only need ONE station. As the users of SRS700’s and Austrons do when Wildwood is active. With GNSS its a hell of a lot harder and without SA your only option is to turn off all the C/A signals hence denying civillian use of GNSS I’m pretty sure if a non-state actor was doing weaponized drone attacks with GPS for guidance, GPS for civilian use would be shut down in a NY minute . Remember govt users would not be affected as they have access to the PPS and the ‘word of the day’ to make it active. You dont need conspiracies to think of conditions where GPS would be shut down for long periods of time and where reasonable people would agree with the shutdown. On Sep 6, 2018, at 8:44 PM, Scott McGrath wrote: Gee, thats strange especially for those of us who ran the Austron comparitors to check our local standards against the LORSTA’s On Sep 6, 2018, at 8:04 PM, Bob kb8tq wrote: Hi No, eLoran *never* on it’s best day could ever deliver the kind of timing that the vast majority of these systems require. It simply is not and can not do the job. The world has moved *way* past the sort of timing it can actually deliver. Bob On Sep 6, 2018, at 6:35 PM, Scott McGrath wrote: Actually we DID have a radio based system that provided sufficient accuracy it was called eLORAN but it was killed by US politicians because they did not want a much more inexpensive to operate system ‘competing’ with GPS.Shutting down LORAN saved 32m dollars annually the NAVSTAR GPS program costs billions annually. Ironically while LORAN’s absolute accuracy is less than GPS, repeatability was much better so fishermen liked LORAN better. Once again the empty suits won and the navigation and timing community lost. Wrt cellsites staying operational i imagine the oscillators in holdover would probably remain sufficiently synchronized for a month or so. On Sep 6, 2018, at 4:56 PM, Bob kb8tq wrote: Hi Well, we *do* have experience with that. It was called selective availability. Indeed it might get turned back on again. It’s impact on a properly designed GPSDO - not much. It takes a bit longer to get to best stability. System time wise, it still works “good enough”. A four hour long test format also does basically nothing to a GPSDO based system. You didn’t read anything in the papers about all cell service in three states going away. The devices did what they are supposed to do and everything did it’s boringly normal thing ….. it worked fine. I still don’t quite understand just what people think could replace satellite based timing in these systems. None of the “radio based” systems are within a factor many thousands to a few million of being adequate. = Now, if this is headed off into a “the government is coming to break down the doors and take away all my toys sort of thing. That’s very much *not* a Time Nuts topic. Bob On Sep 6, 2018, at 11:34 AM, Scott McGrath wrote: And there is the other significant vulnerability since GPS is a MILITARY system the DoD can take it offline for any reason at any time. Leaving civilian users with nothing, If its a national security threat its
Re: [time-nuts] Lost GPS lock or 1PPS recently?
Hi, This is so not my area of interest but I did come across the following quote from the link listed below. "A backup system is also a possible element. The British have demonstrated that eLoran can deliver time with 50 nanoseconds accuracy or better “pretty much anywhere you want to,” said Dana Goward, president of the Resilient Navigation and Timing Foundation." http://insidegnss.com/broad-effort-underway-on-assured-accurate-time-for-critical-infrastructure/ I'm sure someone will identify some hidden "but" in the above claim. I designed the timing hardware for the Loran upgrade well over 10 years ago and haven't thought about it until now. It is fascinating to me that it is still alive and twitching even after it was killed off. It is also interesting to see that the Time-Nut concern about GPS vulnerability is shared by many organizations and governments. Best, Bob Martin On 9/6/2018 6:04 PM, Bob kb8tq wrote: Hi No, eLoran *never* on it’s best day could ever deliver the kind of timing that the vast majority of these systems require. It simply is not and can not do the job. The world has moved *way* past the sort of timing it can actually deliver. Bob On Sep 6, 2018, at 6:35 PM, Scott McGrath wrote: Actually we DID have a radio based system that provided sufficient accuracy it was called eLORAN but it was killed by US politicians because they did not want a much more inexpensive to operate system ‘competing’ with GPS.Shutting down LORAN saved 32m dollars annually the NAVSTAR GPS program costs billions annually. Ironically while LORAN’s absolute accuracy is less than GPS, repeatability was much better so fishermen liked LORAN better. Once again the empty suits won and the navigation and timing community lost. Wrt cellsites staying operational i imagine the oscillators in holdover would probably remain sufficiently synchronized for a month or so. On Sep 6, 2018, at 4:56 PM, Bob kb8tq wrote: Hi Well, we *do* have experience with that. It was called selective availability. Indeed it might get turned back on again. It’s impact on a properly designed GPSDO - not much. It takes a bit longer to get to best stability. System time wise, it still works “good enough”. A four hour long test format also does basically nothing to a GPSDO based system. You didn’t read anything in the papers about all cell service in three states going away. The devices did what they are supposed to do and everything did it’s boringly normal thing ….. it worked fine. I still don’t quite understand just what people think could replace satellite based timing in these systems. None of the “radio based” systems are within a factor many thousands to a few million of being adequate. = Now, if this is headed off into a “the government is coming to break down the doors and take away all my toys sort of thing. That’s very much *not* a Time Nuts topic. Bob On Sep 6, 2018, at 11:34 AM, Scott McGrath wrote: And there is the other significant vulnerability since GPS is a MILITARY system the DoD can take it offline for any reason at any time. Leaving civilian users with nothing, If its a national security threat its likely the other GNSS systems will be unavailable as well. On Sep 6, 2018, at 9:53 AM, John Sloan wrote: Folks: Well blow me down. It took some Google Maps fu on the web on my part, but my time and place does indeed coincide with this “GPS Interference Testing” at White Sands Missile Range. I just happened to be in my home office watching several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham! :John ZDV DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230 -- J. L. SloanDigital Aggregates Corp. +1 303 940 9064 (O)3440 Youngfield St. #209 +1 303 489 5178 (M)Wheat Ridge CO 80033 USA jsl...@diag.comhttp://www.diag.com <http://www.diag.com/> ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- tim
Re: [time-nuts] Lost GPS lock or 1PPS recently?
GPS.gov: Selective Availability https://www.gps.gov/systems/gps/modernization/sa/ Sep 23, 2016 - The United States has no intent to ever use Selective Availability again. In September 2007, the U.S. government announced its decision to procure the future generation of GPS satellites, known as GPS III, without the SA feature. Navstar: GPS Satellite Network - Space.com https://www.space.com › Science & Astronomy Apr 26, 2018 - GPS III's new L1C civil signal also will make it the first GPS satellite ... With selective availability not included on the latest GPS satellites, the ... Hopefully this won't devolve into a discussion about whether one can trust the US Government. Bob Martin On 9/6/2018 3:58 PM, Mark Sims wrote: I read that the latest GPS sats don't even have the ability to implement selective availability... seems a dubious claim to me, though. - Indeed it might get turned back on again. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Lost GPS lock or 1PPS recently?
I'm sure this has been discussed many times here. E-Loran - I designed the timing hardware that controlled the transmitters for that upgrade while I was at Timing Solutions. As I remember it, it was funded by the FAA to be a backup for GPS. The FAA planned to make more use of GPS in the future (distant future given the speed at which the FAA moves). I'm not sure the Coast Guard was excited about the responsibility of running LORAN. Here is a powerpoint presentation arguing for e-loran: https://www.gps.gov/governance/advisory/meetings/2009-05/doherty.pdf Bob Martin On 9/6/2018 4:35 PM, Scott McGrath wrote: Actually we DID have a radio based system that provided sufficient accuracy it was called eLORAN but it was killed by US politicians because they did not want a much more inexpensive to operate system ‘competing’ with GPS.Shutting down LORAN saved 32m dollars annually the NAVSTAR GPS program costs billions annually. Ironically while LORAN’s absolute accuracy is less than GPS, repeatability was much better so fishermen liked LORAN better. Once again the empty suits won and the navigation and timing community lost. Wrt cellsites staying operational i imagine the oscillators in holdover would probably remain sufficiently synchronized for a month or so. On Sep 6, 2018, at 4:56 PM, Bob kb8tq wrote: Hi Well, we *do* have experience with that. It was called selective availability. Indeed it might get turned back on again. It’s impact on a properly designed GPSDO - not much. It takes a bit longer to get to best stability. System time wise, it still works “good enough”. A four hour long test format also does basically nothing to a GPSDO based system. You didn’t read anything in the papers about all cell service in three states going away. The devices did what they are supposed to do and everything did it’s boringly normal thing ….. it worked fine. I still don’t quite understand just what people think could replace satellite based timing in these systems. None of the “radio based” systems are within a factor many thousands to a few million of being adequate. = Now, if this is headed off into a “the government is coming to break down the doors and take away all my toys sort of thing. That’s very much *not* a Time Nuts topic. Bob On Sep 6, 2018, at 11:34 AM, Scott McGrath wrote: And there is the other significant vulnerability since GPS is a MILITARY system the DoD can take it offline for any reason at any time. Leaving civilian users with nothing, If its a national security threat its likely the other GNSS systems will be unavailable as well. On Sep 6, 2018, at 9:53 AM, John Sloan wrote: Folks: Well blow me down. It took some Google Maps fu on the web on my part, but my time and place does indeed coincide with this “GPS Interference Testing” at White Sands Missile Range. I just happened to be in my home office watching several of my GPS-disciplined NTP servers when this occurred. Thanks, Graham! :John ZDV DENVER (ARTCC),CO. [Back to Top] !GPS 08/260 (KZDV A0287/18) ZDV NAV GPS (WSMR GPS 18-20) (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVBL WI A 359NM RADIUS CENTERED AT 45N1063840W (TCS054036) FL400-UNL, 311NM RADIUS AT FL250, 215NM RADIUS AT 1FT, 223NM RADIUS AT 4000FT AGL, 169NM RADIUS AT 50FT AGL DLY 1830-2230 1809031830-1809082230 -- J. L. SloanDigital Aggregates Corp. +1 303 940 9064 (O)3440 Youngfield St. #209 +1 303 489 5178 (M)Wheat Ridge CO 80033 USA jsl...@diag.comhttp://www.diag.com <http://www.diag.com/> ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWV and legal issues
Here is an interesting paper on using fiber: https://pdfs.semanticscholar.org/a37e/04164c01a6bfea2154c8f0dd97f49d1673b0.pdf I believe it used some of the gear that is(was) used in the GPS ground stations around the world. Bob Martin On 9/1/2018 3:29 AM, Magnus Danielson wrote: Hi, It was very telling when I crashed a research group into the reality of phase/time transfer over fiber compared to frequency transfer. Armed with a whiteboard and pens, I derived the forumulas and showed how they worked and not worked. It's a completely different ball-game and their "known tricks" ain't doing nothing good as it comes to time. I had to figure much of this out myself as I did nation-wide system design to achieve the goal. It's a combination of many skills that goes into designing the full system from scratch and make it fit together. It's not hard stuff, it's just many details one needs to get right. Oh the fun. Cheers, Magnus On 08/31/2018 05:15 PM, Bob kb8tq wrote: Hi That works fine if you are doing things manual to check a local standard. If you are trying to disipline a few thousand cell towers 24 hours a day … not so much. It also works for checking frequency. What modern systems need is time. That gets you into a whole world of resolving and identifying individual edges. The WWVB signal really was never set up for this. Loran-C is an example of a signal that was designed to identify a specific edge. Bob On Aug 31, 2018, at 10:30 AM, Martin VE3OAT wrote: But the diurnal phase shifts at VLF are predictable and largely repeatable. Ignore the phase at night and use only the phase records during the day when an all-daylight propagation path exists. You might have to "correct" the absolute phase reading by some multiple of the RF period, but with a low rate of local standard oscillator drift, this is a simple matter of arithmetic. Back in the day, I managed Sulzer crystal oscillators at 5 field sites from my office and could maintain phase continuity for weeks at a time, until we had to diddle the dial on one or several of them to correct for crystal aging. Then it was just more arithmetic again. Several of the oscillators had such low drift rates that all I needed was one daily phase reading from the VLF phase tracking receiver (Tracor 599Js) at those sites to know the frequency of the Sulzers there. ... Martin VE3OAT On Thu, 30 Aug 2018 12:27:12 -0400 Bob kb8tq wrote: WWVB as transmitted ( = right at the input to the antenna) is a wonderfully stable signal. As soon as that signal hits the real world things start to degrade. Propagation between transmit and receive sites is a big deal, even at 60 KHz. On top of that, there is a*lot* of manmade noise at 60 KHz. The receive signal to noise will never be as good as you might like it to be ?. I don't know about WWVB, but for DCF77 it's known that sunrise/sunset causes a phase shift of several 100?s at even moderate distances (like ~500km). Unfortunately I don't have any measurements at hand. Attila Kinali ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] distribution of precision time via fiber networks
Jim, You can still find the Deep Space Network fiber-optic distribution equipment for sale on the Microsemi website: https://www.microsemi.com/product-directory/modular-synchronization-systems/4168-time-code-translator I designed the hardware for NASA's DSN upgrade while at Timing Solutions Corp. I remember having to design and lay out 23 circuit boards within about 5 months when we got that contract. The Time Code Translator was the hardest to get right because it did so much. I never paid much attention to where it went because it was "on to the next project" as soon as it was completed. Still it's nice to see that it got deployed and (hopefully) worked. Bob Martin On 9/1/2018 8:25 AM, jimlux wrote: On 9/1/18 7:00 AM, Scott McGrath wrote: There was a paper published when NASA did something similar for LC39 and the VAB. Anyone have a copy because the link i have is dead. As I recall it was some trick and compensating for thermal effects on the fiber itself was a large part of the effort. I don't know about at the Cape (I'm not sure what the *need* for precision timing at that level might be, but it could be there). There's a whole lot of stuff that's been published about distributing frequency references and holding tight phase tolerances at the Deep Space Network stations, since they do arraying using multiple apertures, as well as run of the mill VLBI stuff. https://deepspace.jpl.nasa.gov/dsndocs/810-005/304/304B.pdf is the "production" system for DSN, but as mentioned therein, there are various improved schemes in development. You might search for publications by Bob Tjoelker. While there are JPL papers in IEEE sources behind paywalls, almost always, they're also available in NTRS (https://ntrs.nasa.gov/) or JPL's piece (https://trs.jpl.nasa.gov/). If the paper isn't online for free in that location, you can send an email to NASA (there's a form at ntrs.nasa.gov) or the JPL librarian (link at the trs site) and they'll send it to you. Another good place to look for DSN related stuff is here: https://ipnpr.jpl.nasa.gov/ The Chinese seem to have been publishing lots of papers on Arxiv recently about "joint time and frequency distribution" ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWVB funding cut
Hi, At Sam Steins retirement gathering last week I asked him about the proposed funding cut. Sam once worked at NIST and had responsibilities in that area. His opinion was that NIST would "dearly like to eliminate those services". It may be more a case of NIST using the budget cuts to further their own ends. Involving a few congressmen or senators might make a difference in a case like this since it affects the general public. Best, Bob Martin On 8/20/2018 3:51 PM, Bob kb8tq wrote: Hi Ok, if it really does include WWVB, that gets a lot of mom and pop voters angry. Bob On Aug 20, 2018, at 5:39 PM, Richard (Rick) Karlquist wrote: It's worse than that, not just WWV, WWVH, but also WWVB: This is an exact quote from page NIST-25 of the proposed FY2019 NIST budget: "NIST will discontinue the dissemination of the U.S. time and frequency via the NIST radio stations in Hawaii and Ft. Collins, CO. These radio stations transmit signals that are used to synchronize consumer electronic products like wall clocks, clock radios, and wristwatches, and may be used in other applications like appliances, cameras, and irrigation controllers." Rick N6RK ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Stuff
Hello, I am not a Time-Nut but I did work in the field for Dr. Sam Stein of Timing Solutions from the time he founded the company in 1991. Ultimately I became one of his three partners and designed the hardware and firmware for most of his products. While I chose not to continue with the company when it was purchased by Symmetricom, for a few years I continued to work for Sam as a contractor on additional products and to support older products. I just attended Sam's retirement gathering in Boulder,CO and received permission to dispose of my many years of collected "stuff" including cables, connectors, old prototypes, raw boards for distribution amps etc along with lots of parts. While I've been asked not to provide full schematics of boards in production, I can provide hints on how they work. There may also be some working zero-crossing detectors from back when I designed the 5110A Time Interval Analyzer as well as isolation amps from as far back as the late 90's when we provided the signal distribution system used in GPS ground stations around the world. My wife claims her biggest fear is that I'll keel over someday and leave her stuck with all this stuff in the basement so I'd like to get rid of it. Sam's retirement was like the end of an era for me and I haven't touched this stuff in years. I'd like it to go to people who can make use of it as opposed to depositing it in a landfill. Ideally there is some Time-Nut in the Boulder, CO area who can take this stuff and who would be willing to share it with other time-nuts at no charge. I also have a 5120 Phase Noise Test Set with internal oscillator. I acquired a new one in a trade for work when Symmetricom asked me to modify the hardware that controlled the transmitters for the Loran upgrade to work as the European version that was under consideration at the time. I would like to donate this unit to an educational institution that can't afford one (but could certainly use it) and would entertain suggestions. Let me know if there is any interest. Best, Bob Martin Former Director of Hardware Development Timing Solutions, Corp. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
