[time-nuts] Positioning Accuracy - Lady Heather vs. T-Bolt Monitor
Hello Time Nuts -My question is --- both LH and T-Bolt Mon will readout position during andat the conclusion of a self survey.The readout from LH provides 2 additional digits of resolution compared to T-bolt Monitor.That is LH provides 7 digits of Lat or Lon to the right of the decimal point; T-bolt Mon provides 5.Now with the understanding that one needs to set a relatively high elevation andamplitude masks to eliminate all but robust signals, and that one must take a lotof samples (48,000 or more) --- Has anyone verified the utility of those extra two digits?By utility I mean - is the 6th decimal place accurate assuming the above constraints.I am trying to nail a position in Longitude to 2 feet or less at a Latitude of 38 degrees N.I have lots of time to take lots of survey points so that is not an issue.Best regards - John k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Suggested Low Noise Transistors
I offer the following for your consideration. Once upon a time - about 1968 Motorola introduced 4 low noise transistors for audio and low frequency applications. There were th 2N5086, 5087, 5088 and 5089. The 5086 and 5087 are PNP and the 5088 and 5089 are NPN. They are almost perfect complements to each other. They are still made though the part numbers are now MMBT2N5088L and so on. As of September 2014 I bought and used several of them in a photo transistor preamp for a laser theodolite receiver. They are commonly available from distributor stock. They differ slightly in noise figure and Beta. Since 1970 I have used them in a number of professional applications from DC up to 50 MHz. The latter a 6 channel summing amplifier for a military mapping photo transistor device. These are some of the hottest bi-polar devices known with a specified minimum beta of 150 at 100 uA. The beta is pretty flat up to 10 mA. The current gain bandwidth product varies from a bit less than 50 at 100 uA up to 500 at 10 mA. At 1 mA it is 200. The low frequency noise figure IS specified - 2N5086 3.0 dB MAX (Ic = 20 uA, Vce = 5 v, Rs = 10 K, from 10 Hz to 15.7 kHz) 2N5087 2.0 dB Max, 1.0 dB typical(Ic = 100 uA, Vce = 5V, Rs = 3K, f = 1.0 kHz) Data is provided for the effect of source resistance and Ic on the noise figure. Data for the complementary 2N5088 and 2N5089 is nearly identical. You can look it up. It is all on the data sheet for the original devices and may be found in the Semiconductor Data Handbook issued my Motorola in the 1970. the data may also be on the ON semiconductor web site among other places. With their relatively low high frequency response (as compared to a 2n2857) you are not risking oscillations up in the the microwave bands where most of you do not have the test gear to find and fix any funny business. This is a really nice calm set of devices and easy to use. I believe that when I bought them last year they were around a buck each. The 5086 and 5087 are PNP and the 5088 and 5089 are NPN. They are still made though the part numbers are now MMBT2N5088L and so on. As of September 2014 I bought and used several of them in a photo transistor preamp for a laser theodolite receiver. They are commonly available from distributor stock. I have not applied them in low noise oscillator applications and have no idea as to their suitability for that. But they are one hell of a transistor family and worth knowing about. Best regards john c roos K6iql spring hill ks ___ 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] T.I. questions (Magnus Danielson)
A further comment on design of pseudo random code generators. At some point the code may enter the dreaded all zeros state. This clocks a zero on the input stage through all stages and the whole thing just stops. So a AND gate looking at all stages in parallel is used to detect the all zero state and get things going again. One way is to XOR the output of the AND and the input to any stage. since the all zero state is not permitted the length of the code is can be no longer than the well known 2^n -1 bits. Also if the number of codes desired is limited - some of the FFs may be replace by a delay line. Using MECL III and a delay line a 350 MHz rather long code generator was implemented in my lab with only few JK FFs. That was in about 1979. For more info see Dixon Spread Spectrum Systems. john roos k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Hp Family GPS DOs vs. Tbolts Rev 3 SW and Trimble VCXO
With all of the discussion of the recent availability of various HP family GPS DO devices, I was wondering if I should get a couple. Presently I have a couple of T-bolts that seem to serve me well. What wold be the advantages gained by going to the HPs. Need 10 MHz output though. Any thoughts? -73 john roos k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] 5 to 10 MHz Quadrature Driven Mixer Doubler
I have received permission to distribute copies of my QEX article on this subject from ARRL. In addition to the article I will include full size schematics and color photos of the various assemblies. The design includes an adjustable 10 MHz output amplifier for driving 50 OHM loads. If interested please email me off list at johncr...@aol.com I will wait a few days and then mail a complete package to all requestors. Best regards to all - 73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] 5 to 10 MHz Quad Driven Mixer doubler article
Apparently there is some interest in this technique. So far I have 35 requests and still counting. Please if you do want a copy send me an email OFF LIST to johncr...@aol.com. Requests posted on list are too hard to find and too hard to make into a master address list. In addition to the basic article I will add some related material. And as they say on TV thats not all. One QEX reader asked how it compares with the classic push-push doubler. I prepared a brief paper on the push-push doubler and will include it as well. They are both useful depending upon the host application. For one thing the push-push circuit can give healthy power gain and power output up to a Watt or more. I plan to fire off the package on Sunday. Best regards to all - john c roos k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Cutler NAA on 24.0kHz....
A good approach to carrier recovery would be the following chain - 1 AGC or limiter amplifier - I would use AGC followed by a limiter to keep the input to the doubler constant. 2 Analog Frequency Doubler with a bit of Q in the tank tuned to 2X carrier frequency Digital when it screws up does so with bad manners. The tank provides some frequency memory - not obtainable with a digital doubler. 3. A slow PLL that locks onto and tracks the 2X carrier frequency. I would use a counted down VCXO for this to ensure a long coast time. Loop bandwidth should be of the order of seconds or more and have a damping factor of 1 or more. the classic 0.707 damping tracks fast but overshoots and hunts before settling down. Fast tracking is not the requirement here. Stable control of the PLL is. 4. A 2x divider stage to output the original carrier frequency. This could be a flip flop as the amplitude output of the PLL would be constant. I have made a few PSK and BPSk carrier recover circuits of this type for both micrwave spread spectrum links (20 GHz and UP and also for use with FSK at VHF). If the carrier is stable and there is no Doppler a very slow Pll does a world of good. See Gardner Phase Lock Loop Techniques. the whole thing could be built on little more than 8 square inches of PWB and I am being generous. MSK is alive and well in a couple of FAA procurements, both past and present. The appeal is the constant envelope and reduction of adjacent sidebands. John Roos K6IQL -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sun, Aug 17, 2014 8:21 am Subject: time-nuts Digest, Vol 121, Issue 45 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Cutler NAA on 24.0kHz (Kenneth G. Gordon) 2. Re: Cutler NAA on 24.0kHz (Kenneth G. Gordon) 3. Re: Cutler NAA on 24.0kHz (Kenneth G. Gordon) 4. Re: Cutler NAA on 24.0kHz (Kenneth G. Gordon) 5. Re: Cutler NAA on 24.0kHz (paul swed) 6. Re: Cutler NAA on 24.0kHz (Kenneth G. Gordon) 7. MIT Flea (bownes) 8. Proper way to manually connect Vfc (Ole Petter Ronningen) -- Message: 1 Date: Sat, 16 Aug 2014 09:20:34 -0700 From: Kenneth G. Gordon kgordon2...@frontier.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Cutler NAA on 24.0kHz Message-ID: 53ef84d2.25672.cd9f...@kgordon2006.frontier.com Content-Type: text/plain; charset=ISO-8859-1 On 16 Aug 2014 at 11:33, Bob Camp wrote: Hi I would be *very* surprised if the NAA antenna was 50% efficient (transmitter RF to radiated power). According to this: http://www.scribd.com/doc/145116437/THE-BIGGEST-LITTLE-ANTENNA-IN -THE-WORLD-US-Navy-s-VLF-antenna-at-Cutler-Maine The company which designed and built the dual trideco antenna system at Cutler had to guarantee 50% radiation efficiency, and they achieved an antenna radiation efficiency of 74.9% when using the 6 panel trideco. When I read this, I was truly amazed. Although, this site: http://www.navy-radio.com/commsta/cutler.htm does say that with 2 MW input, the ERP is 1 MW, which would indicate at least 50% radiation efficiency. I am still amazed. Given that it?s already up and running with good signal levels, that?s not a big deal. Very true indeed. Ken W7EKB -- Message: 2 Date: Sat, 16 Aug 2014 09:26:40 -0700 From: Kenneth G. Gordon kgordon2...@frontier.com To: paul swed paulsw...@gmail.com Cc: time-nuts@febo.com Subject: Re: [time-nuts] Cutler NAA on 24.0kHz Message-ID: 53ef8640.15583.cdf9...@kgordon2006.frontier.com Content-Type: text/plain; charset=US-ASCII On 16 Aug 2014 at 10:24, paul swed wrote: Ken At least last night NAA was running just fine using a fluke 207 and 4 ft of wire. The antenna is behind a metal rack that shields it in NAAs direction. Ha! At VLF you could probably bury your antenna in a grounded, steel pipe 4 feet into the ground and still hear NAA. I did that test out of curiosity. I LOVE curious... :-) Granted its 2 MW but then again the antenna is at best 50% efficient. See previous post. Who knows maybe they have sections of the antenna down for maintenance. The reason NAA has a double trideco is so they can continue to transmit with one section down for maintenance. It turns out that Cutler has a much-bigger-than-usual problem with lightning... Ken W7EKB
Re: [time-nuts] Topic Cops
I am so sick and tired of the topic cops. I do not know how many interesting discussions I was following, that they have killed. In all of my years as an electrical engineer and engineering VP this group has some of the most unfriendly and pretentious individuals I have ever encountered. It's not as if the time domain was filled with two dozen state of the art discussions competing for space, because it is just not so. Please, if people are learning and growing, let it be as long as the topic is at least somewhat related to time and related devices. This certainly includes battery backup systems. Please be more tolerant. It is a hobby as well as a profession. Best regards john c roos K6IQL -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Mon, Jul 28, 2014 10:00 am Subject: time-nuts Digest, Vol 120, Issue 85 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: OT Gel Cell question (John Allen) -- Message: 1 Date: Mon, 28 Jul 2014 10:53:03 -0400 From: John Allen j...@pcsupportsolutions.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Subject: Re: [time-nuts] OT Gel Cell question Message-ID: 016f01cfaa73$a2af9290$e80eb7b0$@pcsupportsolutions.com Content-Type: text/plain; charset=iso-8859-1 That's for sure. Lead Acid batteries run everything except where power density is critical. We all need to know as much as possible about them. I thought that I knew a lot, but the dialogue on this list has raised my understanding significantly. Thanks to all who have contributed so far. A treasure trove of information. Regards, John K1AE ? Sent: Monday, July 28, 2014 8:39 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] OT Gel Cell question Ever use batteries to back up your time toys David? I would bet they were lead acid. More that a few folks on this group are using lead acid to run such things. Discussions of charging, discharging, and care of batteries is just as apropos, in my opinion, as discussions on which coax to use, or which receiver to use to run your GPSDO... Or for that matter which SBC to use to run your favorite time hack. It is all part of the infrastructure necessary to make the study of fine time possible. -Chuck Harris David C. Partridge wrote: Back to time related discussions please. Thanks Dave -- ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 120, Issue 85 ** ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 117, Issue 80
The FT-243 holders I revamped in the 1950s and 60s did have the aforementioned spring. However a close look at the electrode plates that contacted the quartz resonator had, in every case, a raised boss at each corner that spaced the center of the electrode a few mills above the center of the quartz. So the center part of the quartz was not restrained from moving. And it was not compressed by the spring. As I recall the stack up was lower electrode, quartz resonator (square in the case of the FT-243) upper electrode, edge seal with hole for the spring, the spring, and then the cover. I reworked quite a few of these at 8 MHz for use on the 2 meter band by multiplying by 18X. 8 x 18 = 144 MHz. Tooth paste moved them up and a small scratch with a bit of solder moved them down. Re: optically excite a quartz crystal? (Bob Camp) As for Bliley - go to the web site and if you look around, you can find a fascinating history of the company. It included details of the invention of the etch process and also of the rubber rock technique to vary the frequency of a crystal. They still make some of the best resonators for custom designed oscillators around. I used them last in a synthesizer design for a FAA customer VHF/UHF receiver only about 6 years ago. -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Mon, Apr 21, 2014 11:00 am Subject: time-nuts Digest, Vol 117, Issue 80 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: optically excite a quartz crystal? (Bob Camp) 2. Re: optically excite a quartz crystal? (Bob Camp) -- Message: 1 Date: Mon, 21 Apr 2014 11:24:43 -0400 From: Bob Camp li...@rtty.us To: Poul-Henning Kamp p...@phk.freebsd.dk Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] optically excite a quartz crystal? Message-ID: 402dec2b-2405-493a-9866-31cc2ca88...@rtty.us Content-Type: text/plain; charset=windows-1252 Hi As with all ?good stories? there are many versions told by many people. I?ve heard far to many mutually contradictory versions to have any real idea what?s true. You are correct that etching was a known process in the 1930?s and that it had been used by various people at various times. Since it added time (and complexity) to the process, it got dropped by most people to speed up production ? Bob On Apr 21, 2014, at 10:51 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message a5032606-d7d7-4231-b1bd-434670274...@rtty.us, Bob Camp writes: Early in the WWII era, quartz blanks were not commonly etched after begin ground / polished to frequency. This left debris on the surface of the blank. The net result was that the resonators failed after a period of time in the field, especially under damp conditions. The problem got so bad that it actually threatened the ability to communicate in 1942. A fairly high level team looked into the issue and etching of blanks (and a few other mods) were made a mandatory part of all crystals suppled to the government. The story is slightly more interesting than that: Blileys crystals were almost totally without these problems, but they wouldn't tell why that might be. In the end the government put a lot of pressure on Bliley to squeeze out the manufacturing secret. The secret was etching. To keep it secret, Bliley had called it something along the lines of X-Grind and not applied for a patent. The Government forced Bliley to share the etching secret without giving any compensation, and the Blileys were bitter about that for the rest of their lifes. -- 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. -- Message: 2 Date: Mon, 21 Apr 2014 11:26:16 -0400 From: Bob Camp li...@rtty.us To: j...@quikus.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] optically excite a quartz crystal? Message-ID: 6b374045-7b1f-4706-8b38-609b4366b...@rtty.us Content-Type: text/plain; charset=windows-1252 Hi Well I can name at least one post war ham (me at age 14) who did not understand the need for etch after grinding? Bob On Apr 21, 2014, at 11:21 AM, J. Forster
Re: [time-nuts] GPS antenna in silicon/RTV encapsulation
For the group - Re: [time-nuts] GPS antenna in silicon/RTV encapsula I have been reading the comments on this for a few days. Here is the scoop - Almost every adhesive known to man is absolute bad news when applied to RF components. Adhesives are sticky because they consist of polar molecules that tend t align with any RF field. Water is a polar molecule and that is why is get hot in a microwave field. So in general, adhesives are very lossy at even low RF frequencies. There is a subset of the Microwave industry that provides well characterized adhesives to that industry. Special foams have been developed for potting of microwave antennas and even those cause changes in impedance and pattern that the designer must account for. The parameters you are interested in are the dielectric constant which will determine how much the velocity of propagation is reduced in the material, and the loss tangent which is the microwave version of the dissipation factor' often specified for dielectric in capacitors. You want a low dielectric constant and a very low loss tangent - approaching 0. These are not commonly in adhesives. That is why Potted antennas are often potted in a foam consisting of not a lot of adhesive and a lot of low loss gas bubbles. Google loss tangent for more information. The short answer from this olde microwave engineer - do not try to pot your antenna, it will be rendered inoperative unless you use one of the microwave specified potting materials. Rather provide an air filled enclosure / radome of some very thin walled plastic. -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Fri, Apr 18, 2014 10:00 am Subject: time-nuts Digest, Vol 117, Issue 66 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: time-nuts Digest, Vol 117, Issue 61 (HagaaarTheHorrible) 2. Re: GPS antenna in silicon/RTV encapsulation (Jim Lux) 3. quartz clock/watch question (Robert Roehrig) 4. Re: time-nuts Digest, Vol 117, Issue 61 (Bob Camp) 5. Re: Measuring the accurcy of a wrist watch (Chris Albertson) -- Message: 1 Date: Fri, 18 Apr 2014 15:17:58 +0200 From: HagaaarTheHorrible hagaaar587pl...@googlemail.com To: time-nuts@febo.com Subject: Re: [time-nuts] time-nuts Digest, Vol 117, Issue 61 Message-ID: a14e3790-e838-4043-8344-d371f9b81...@googlemail.com Content-Type: text/plain; charset=us-ascii Hi Dave and thanks for the quick answer! My thesis is about a phase noise measurement device I developed, which primary use is to measure phase noise/jitter of audioband DACs. I probably won't be focussing on jitter too much but would like to know if there even is one accepted standard definition. For example, in the different definitions I found so far, the seperation between jitter and wander sometimes is given to be at 1Hz, 10Hz and sometimes just mushy definitions like very low frequencies... I doubt it is that important for my thesis anyway, but I'd really like to know for myself, so if anyone has a pointer for me it would be greatly appreciated! Von: Dave Brown tract...@ihug.co.nz Datum: 17. April 2014 11:21:25 MESZ An: Discussion of precise time and frequency measurement time-nuts@febo.com Betreff: Re: [time-nuts] Jitter Definition Antwort an: Discussion of precise time and frequency measurement time-nuts@febo.com It depends on what your thesis is all about- you could try some of the ITU documents for 'official' definitions but these may or may not be relevant to your thesis. DaveB, NZ - Original Message - From: HagaaarTheHorrible hagaaar587pl...@googlemail.com To: time-nuts@febo.com Sent: Thursday, April 17, 2014 2:54 PM Subject: [time-nuts] Jitter Definition Hello there, I tried searching the archives (and google, IEEE, NIST, ITU), but didn't really find a satisfying answer, so I thought I'd ask directly. In short: Is there any kind of standard definition for Jitter which is commonly accepted? I (think I) understood Jitter and phase noise by now, yet I need to give some references in my bachelor's thesis, so I'm looking for a definition. So far I haven't found a real definition of the different types (RMS,p2p,c2c,...) and components(RJ,DJ) of Jitter, but I guess there must be some kind of accepted standard!? If anyone could point me to some official sources which are accepted in the industry,
[time-nuts] HP 10811 - 60165 Info Request
I have acquired one of these double oven oscillators. Seems like a useful thing. Need info on pin outs, and operating voltages. Also any other useful information or links to same would be appreciated. Please reply off list with any files of specs etc to my email - johncr...@aol.com All help appreciated. Best regards to all john c roos k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Alfred Loomis
As it turns out Loomis did the original work proving the effect of the moon on pendelum clocks, eatrhs rotation rate and so. He arranged with Bell Labs to have their quartz frequency standard transferred by a land line he leased to his lab. The experiments took several months. The results were published as The Precise Measurment of Time in the Monthly Notices of the Royal Astronomical Society. According to Luis Alvarez, Loomis was a time nut for the rest of his life. Later in life, again according to Alvarez he wore two Accutrons which he checked daily against WWV. (I only had one!) The details are in the Tuxedo Park book . I just read all about it and the above is the briefest summary. For more buy the book; its about 10 bucks. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Shortt Clock Recent Measurements (Brooke Clarke)
It is not surprising that one can find little about Alfred Loomis. He was notoriously publicity shy and never gave interviews. Before his death he had much of research material disposed of. However the private lab he created at Tuxedo Park NY. was a gathering place for all of the key scientists of his time. He used his considerable fortune to fund the research of promising scientists. If anything was hot in physics in the 30's and early 40's he was there. For example he is in a photo taken at the early Berkley Summer Study where the greats in physics gathered to determine the feasibility of the A-Bomb. He was probably the last of the great Gentleman Scientists. A great read is Tuxedo Park by Jennet Conant (yep of the same family) first published in 2002. I read a borrowed copy then. And with all the discussion about him, I recalled the book. I tried Amazon and just got a Kindle edition. (The amazon listing mentions Oppenheimer, but the book is all about Loomis). Read the reviews if interested. - 73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Crude Survey Technique
When I asked about Crude Survey Techniques I never expected results much better than the 10 ft accuracy someone volunteered from the first. In a former life I ran an engineering department that worked on the old FAA SCAT-1 DGPS landing project, where I did learn a bit about GPS and its limitations for L1 positioning. Thus the title Crude I realize that any number to the right of the 5th decimal point reported by T-Bolt mon is likely bogus. The data I reported earlier pretty much supports that. Now I am running tests with 3 units set for 10K, 20K, and 40K fixes to see how long each takes and to compare results obtained. In any case using a 400 to 600 ft base line between fixes should establish my north- south line. The I will check it with compass(crude) and the sun shadow method. All comments and contributions most appreciated - john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Crude Survey Technique (WarrenS)
Warren, Understood. I have a couple more questions. Once the thunderbolt has completed a survey, does it continue to update its position or are the final numbers at the end of the survey frozen until a new survey has started. If it continues to update the logging feature in the thunderbolt monitor outputs the data in a convenient format.I will also give Lady Heather a try. it has several operational modes such as; stationary, land and a couple of others. Which mode would be most useful to determine a fixed position. I have three of the little beasties chugging away and doing an initial survey. Later on this evening I'll see what they come up with. Thanks for your help – John Re: Crude Survey Technique (WarrenS) -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sat, Nov 23, 2013 1:07 pm Subject: time-nuts Digest, Vol 112, Issue 80 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Crude Survey Technique (WarrenS) -- Message: 1 Date: Sat, 23 Nov 2013 11:03:54 -0800 From: WarrenS warrensjmail-...@yahoo.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Crude Survey Technique Message-ID: CBA8FAFF2BCD4EF2A5A2D6B98BF891DB@Warcon28Gz Content-Type: text/plain; charset=iso-8859-1; Format=flowed John In answer to your original questions, No problem if you have a good setup including a good sky view, antenna, and TBolt setup. It is important to do each run at the different locations at the same time of the day and average the results for as long as you can. Best is to do a 24 Hr survey at each location. see the attached LH plot for the effect of time on location reading error. Multiple Tbolts on the same antenna don't help, unless they are on different antennas. ws *** - Original Message - From: johncr...@aol.com To: time-nuts@febo.com Sent: Thursday, November 21, 2013 10:52 AM Subject: [time-nuts] Crude Survey Technique I wish to establish a north south line on my property to an accuracy of +/- 2 degrees. Could this be done by loading a T-bolt, Antenna, Power source, and laptop into my little red wagon? The idea being to find two positions several hundred ft apart where either LH or T-bolt Mon report the same latitude? Will either of these programs report to sufficient accuracy? The base line would be 300 ft, though more is possible.I realizes that the T-bolt is not a survey device, but I can spend several hours fixing each position if required. All comments appreciated.?? -73 john k6iql Question - If I use 3 T-bolts on the same antenna, feedline, splitter etc. and run 3 instances of T-bolt mon - can the results be improved??? -- next part -- A non-text attachment was scrubbed... Name: ws-1-3D#2.gif Type: image/gif Size: 34594 bytes Desc: not available URL: http://www.febo.com/pipermail/time-nuts/attachments/20131123/1497b620/attachment.gif -- ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 112, Issue 80 ** ___ 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] Crude Survey Technique
Stephen - [time-nuts] Crude Survey Technique Thanks for describing your method. I am learning a lot. here is agovt web site that will give the compass correction for any long and lat. Here in KS the magnetic pole is about 2.3 degrees to the east. Once all the ideas are in, I will put together a summary. I have a number of the required tools, compass, several T-bolts, surveyor's transit, tall poles, laser level, and bulls-eye levels. So with all of these good ideas I am sure I will get it right. It will be interesting to cross check the various methods. It also occurred to me that I could buy a 3 ft length of hardened steel shafting, wrap a couple of dozen turns of # 6 around it and then connect it to a big lead acid battery via a 200 Amp fuse. Should result in a 3 ft long compass needle. You only get to use the fuse once though! Thanks to all -john -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Fri, Nov 22, 2013 6:29 am Subject: time-nuts Digest, Vol 112, Issue 75 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Motorola M12+ (Azelio Boriani) 2. Re: Isolation achieved by opamp based isoamp? (Bruce Griffiths) 3. Re: DMTD: Mixer DC offset will result in time offset at zero-crossing detector out? (Bruce Griffiths) 4. Re: Crude Survey Technique (Stephan Sandenbergh) 5. Re: Strange 100ns jumps on Motorola M12+T (Bob Camp) 6. Re: DMTD: Mixer DC offset will result in time offset at zero-crossing detector out? (Stephan Sandenbergh) -- Message: 1 Date: Fri, 22 Nov 2013 11:45:17 +0100 From: Azelio Boriani azelio.bori...@screen.it To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Motorola M12+ Message-ID: cal8xpmppu6e2g90veafkzmdqvpmse+ql+uxr6+rcvhuueyd...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 Strange item... it has an M12+ and a supporting board full of components. Protocol translation from 12-channel to 8-channel? The link to the PDF file returns a 404. On Fri, Nov 22, 2013 at 9:32 AM, Pascual Arbona Lopez p.arb...@securimar.com wrote: I am wondering if this is a sustitute of the original oncore VP receiver for the Z3801 -Z3805. (E-pay 281161070304 ) ___ 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. -- Message: 2 Date: Sat, 23 Nov 2013 00:18:50 +1300 From: Bruce Griffiths bruce.griffi...@xtra.co.nz To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Isolation achieved by opamp based isoamp? Message-ID: 528f3d9a.5090...@xtra.co.nz Content-Type: text/plain; charset=ISO-8859-1; format=flowed Stephan Sandenbergh wrote: Something that would be interesting to know is if certain opamps are better suited toward S12 isolation than others. I guess at the expense of noise floor and 1/f corner one could cascade two opamps to improve the S12 isolation further. The flicker noise corner of an opamp may be lower than you think. Current feedback opamps may have higher flicker noise corners than volt feedback opamps As soon as you are looking at frequencies of 100MHz you are probably left with the discrete options in any way. There are 1GHz and 10GHz opamps available. Bruce On 22 November 2013 11:45, Stephan Sandenberghssandenbe...@gmail.comwrote: Thanks for the spec. I suspected that it would be in that ball park. The discrete transistor type amplifiers achieve around 120dB or more at 10MHz. But, they are a lot more effort to implement than the opamp designs. I believe the transformer in this case is for ground loop isolation rather than S12 isolation. On 21 November 2013 20:20, Charles Steinmetzcsteinm...@yandex.comwrote: Corby wrote: This opamp buffer has 80-90db isolation. That is typical at 5 to 10 MHz *if* (i) all of the splitting is done on the input side (i.e., each output has its own op amp), and (ii) the splitter and all of the construction (grounds, shielding, etc.) is done correctly. If any splitting is done on the output side of the op amp(s), by using one op amp to drive more than one output through separate back terminating resistors, the outputs that share an
Re: [time-nuts] Crude Survey Technique
Hello and thanks to all for the great ideas. Re: [time-nuts] Crude Survey Technique Some interim comments: *agree with regard to using pole star. However it is below freezing here and so I won't be out in the dark with my camera. A good verification technique that must await warmer weather!! *thanks for the suggestion re. the transit. Unfortunately the elevation measurement only goes to 30 degrees and I am at 38.7 degrees latitude. I should have bought the one with more elevation range and a built in precision compass. Still might do that. *I have a Stocker and Yale Army compass - nice thing but 2 degrees is probabily beyond its capability except as a sanity check *Forced my T-bolt to find itself 9 times in the last 24 hours: Average Longitude : -94.70983 Extreme Spread :90 degrees Standard Devation : 2.58 e-5 degrees At my latitude 1 degree is 285,402.9 Ft So the error at 1 standard deviation is 7.4 ft. Who ever guessed 10 ft has achieved GURU status. So doing the ATAN at various ranges we get 200 ft 2.12 degrees 400 ft 1.06 degrees 600ft 0.71 degrees. 400 ft is easy and 600 is possible. However the sun shadow method seems an equally good approach. Question - If I use 3 T-bolts on the same antenna, feedline, splitter etc. and run 3 instances of T-bolt mon - can the results be improved??? Thanks for all the help - john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Fri, Nov 22, 2013 1:35 pm Subject: time-nuts Digest, Vol 112, Issue 77 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Crude Survey Technique (Robert Atkinson) 2. Re: DMTD: Mixer DC offset will result in time offset at zero-crossing detector out? (Bruce Griffiths) 3. Re: Isolation achieved by opamp based isoamp? (Charles Steinmetz) 4. Re: Off-Topic Question -- German Composition Resistors (Didier Juges) 5. Re: Thunderbolt Simulator (paul swed) 6. Re: Crude Survey Technique (Brian Lloyd) -- Message: 1 Date: Fri, 22 Nov 2013 17:06:51 + (GMT) From: Robert Atkinson robert8...@yahoo.co.uk To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Crude Survey Technique Message-ID: 1385140011.91089.yahoomail...@web171902.mail.ir2.yahoo.com Content-Type: text/plain; charset=iso-8859-1 Hi Jim, I disagree, the Medium Landing Compass IS accurate to better than 30 minutes (0.5deg). This is also the smallest graduation so it can be read to better than 15 minutes. The calibration chart is given to 10 minutes every 15 degrees. It does of course indicate the orientation of the local magnetic field. To ensure there is no local distortions you need to do a site survey. This can be acheived by comparing bearings to a distant object along a baseline or taking reciprical bearings. CAA CAP562 part 8 leaflet 1 http://www.helitavia.com/docs/CAP562_2007_08.pdf? has lots of good info. (full version here http://www.caa.co.uk/docs/33/CAP562RFS.pdf? large file over 10MB) Robert G8RPI (CEng, licenced aircraft engineer for 30 years, I've done many aircraft swings)? From: Jim Lux jim...@earthlink.net To: time-nuts@febo.com Sent: Friday, 22 November 2013, 14:25 Subject: Re: [time-nuts] Crude Survey Technique On 11/21/13 11:32 PM, Robert Atkinson wrote: I'd also go for a compass if you want magnetic north, but then I have a good one, a medium landing compass. Mine dates from WWII but they are still made http://www.sirs.co.uk/ground/landing_compasses/patt2/landing_resource These are used to align the standbay and remote reading compasses on aircraft. Good to half a degree. If you need better ther is the Watts Datum Compass. Robert G8RPI. That compass is *precise* to 1/2 degree, but not *accurate* to 1/2 degree. It comes with a calibration card, and is presumably used in a place with a uniform field (e.g. for calibrating an aircraft compass, which is done in an open area with no known magnetic anomalies).? If you're in a different environment, the card values may be incorrect. It is essentially as comparison standard.? You put it next to the aircraft and move both in a systematic pattern and you use it to calibrate out the variations in the plane's internal compass. However you're going to be subject to the local magnetic field anomalies (and they're surprisingly large).
Re: [time-nuts] Crude Survey Technique (johncr...@aol.com)
My thanks to all that contributed ideas, especially Don's sundial approach. You all have established that if there is an excessively? complex approach I will be sure to think of that first. Let see what else pops up. -73 john k6iql -Original Message- From: time-nuts-request lt;time-nuts-requ...@febo.comgt; To: time-nuts lt;time-nuts@febo.comgt; Sent: Thu, Nov 21, 2013 2:31 pm Subject: time-nuts Digest, Vol 112, Issue 68 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Off-Topic Question -- German Composition Resistors (Robert LaJeunesse) 2. Crude Survey Technique (johncr...@aol.com) 3. Re: Crude Survey Technique (Poul-Henning Kamp) 4. Re: Crude Survey Technique (Don Latham) 5. Re: Crude Survey Technique (Don Latham) 6. Re: Crude Survey Technique (J. Forster) 7. OT: Putting the Wolfram Language (and Mathematica) on every Raspberry Pi (David J Taylor) 8. Re: Crude Survey Technique (Brian Lloyd) -- Message: 1 Date: Thu, 21 Nov 2013 10:38:10 -0800 (PST) From: Robert LaJeunesse lt;rlajeune...@sbcglobal.netgt; To: Discussion of precise time and frequency measurement lt;time-nuts@febo.comgt; Subject: Re: [time-nuts] Off-Topic Question -- German Composition Resistors Message-ID: lt;1385059090.6740.yahoomail...@web181003.mail.ne1.yahoo.comgt; Content-Type: text/plain; charset=iso-8859-1 If it had 4 color bands 2701 you are likely reading it backward. 1072 would be 10.7K Bob L. gt; gt; From: brucekar...@aol.com lt;brucekar...@aol.comgt; gt;To: time-nuts@febo.com gt;Sent: Thursday, November 21, 2013 1:11 PM gt;Subject: [time-nuts] Off-Topic Question -- German Composition Resistors gt; gt; gt;While tracing out a PC board from an instrument manufactured in Germany, I? gt;quickly discovered the color code on 1/4-watt composition resistors is not? gt;the same as that commonly used in the US? For example, I would measure? gt;about 10,000-ohms across a presumably good resistor that appeared to be marked? gt;2700-ohms.? Has/does Germany used a different code for such parts? gt; gt;Bruce, KG6OJI gt;___ gt;time-nuts mailing list -- time-nuts@febo.com gt;To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts gt;and follow the instructions there. gt; gt; gt; -- Message: 2 Date: Thu, 21 Nov 2013 13:52:49 -0500 (EST) From: johncr...@aol.com To: time-nuts@febo.com Subject: [time-nuts] Crude Survey Technique Message-ID: lt;8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.comgt; Content-Type: text/plain; charset=us-ascii I wish to establish a north south line on my property to an accuracy of +/- 2 degrees. Could this be done by loading a T-bolt, Antenna, Power source, and laptop into my little red wagon? The idea being to find two positions several hundred ft apart where either LH or T-bolt Mon report the same latitude? Will either of these programs report to sufficient accuracy? The base line would be 300 ft, though more is possible.I realizes that the T-bolt is not a survey device, but I can spend several hours fixing each position if required. All comments appreciated.?? -73 john k6iql -- Message: 3 Date: Thu, 21 Nov 2013 19:11:51 + From: Poul-Henning Kamp lt;p...@phk.freebsd.dkgt; To: Discussion of precise time and frequency measurement lt;time-nuts@febo.comgt;, johncr...@aol.com Subject: Re: [time-nuts] Crude Survey Technique Message-ID: lt;11440.1385061...@critter.freebsd.dkgt; Content-Type: text/plain; charset=ISO-8859-1 In message lt;8d0b5020292d91e-cc0-4b...@webmail-vm026.sysops.aol.comgt;, johncroos@ aol.com writes: gt; I wish to establish a north south line on my property to an gt;accuracy of +/- 2 degrees. First of all, at that level of precision you will have to decide what you mean by north south ? Magnetic ? Geodetic ? (if so: Which Datum ?) Meridian ? gt; The base line would be 300 ft So your east-west precision needs to be tan(2)*300ft = 10.5 ft. I don't think you can do that with a single band GPS. If you can locate suitable landmarks, you may be able to do with the arial photograph on maps.google.com (or similar servce) but you need to get coordinates figured
[time-nuts] Crude Survey Technique
I wish to establish a north south line on my property to an accuracy of +/- 2 degrees. Could this be done by loading a T-bolt, Antenna, Power source, and laptop into my little red wagon? The idea being to find two positions several hundred ft apart where either LH or T-bolt Mon report the same latitude? Will either of these programs report to sufficient accuracy? The base line would be 300 ft, though more is possible.I realizes that the T-bolt is not a survey device, but I can spend several hours fixing each position if required. All comments appreciated.?? -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Mains frequency (Tom Van Baak)
Tom - Attached is an example from mains data that Bill just collected with picPET and that TimeLab plotted. I really got to get one of these one day. Thanks for the lead. -john k6iql- -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sun, Nov 17, 2013 9:53 am Subject: time-nuts Digest, Vol 112, Issue 50 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Mains frequency (Bill Dailey) 2. Re: Mains frequency (Tom Van Baak) (johncr...@aol.com) 3. Re: Loran (bill.riches) 4. national nc2001 atomic clock on eBay (jmfranke) 5. Re: national nc2001 atomic clock on eBay (Tom Van Baak) 6. Re: Loran (Brian Lloyd) 7. Re: Mains frequency (Tom Van Baak) (Tom Van Baak) -- Message: 1 Date: Sat, 16 Nov 2013 21:49:10 -0600 From: Bill Dailey docdai...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Mains frequency Message-ID: 06599006-ce82-476d-b24f-051c9ebfd...@gmail.com Content-Type: text/plain; charset=us-ascii This resonates with me somewhat since I used to run nuclear power plants and operate the actual turbines. It does seem that the time interval measurements have much more jitter than I would expect. I suspect the thousands of turbines phase locked may introduce all kinds of very subtle variations. I do know when you put a submarine turbine on shore power (grid). You no longer have to control speed... The grid does that for you. Sent from my iPad On Nov 16, 2013, at 9:35 PM, Charles Steinmetz csteinm...@yandex.com wrote: tvb wrote: I think we agree. Just to clarify... I rely on no hardware and no software filters when I use a time-stamping counter such as a sub-nanosecond Pendulum CNT-9x or sub-microsecond picPET. An electrical zero-crossing happens when it happens. If you filter you're just trying to change history: spikes are spikes; noise is noise; history is history. Deal with it. Record it, don't filter it away. Well, it depends on what one wants to investigate. The naked history one captures with no filtering may not be the cleanest history available of the phenomenon under investigation. Except in unusual circumstances, mains voltage is generated by massive rotating machinery -- so anything fast that happens on your incoming mains voltage is not a reflection of the grid frequency. If what you want to know is the grid frequency over time (vector sum of the rotational velocity of the various generators on the grid, as seen from your location), a filtered and limited signal may (probably will) provide the best assessment. Note that local zero crossings are only a proxy for grid frequency to begin with -- and not a very good one, specifically because of the high noise level. Of course, you can always filter in software if you time-stamp each zero cross in all its naked glory, but removing the noise prior to time-stamping is often preferable to digitally processing a noisy capt ure. Put another way, the massive rotating machinery that generates the mains voltage can only change the zero cross of the grid by a tiny amount from one cycle to the next. If a data capture method shows cycle-to-cycle jitter that is significantly greater than this amount, the increase cannot be due to the generators, it can only be due to noise. If one's interest is the grid frequency, removing this noise prior to time-stamping can only help. Note that I'm not talking about a filter Q in the millions -- I'd probably be inclined to use a linear-phase filter with several Hz bandwidth, after a more rigorous analysis of the application. You can either focus on the signal, or the noise. That's two separate plots. Agreed. If you are investigating incidental noise on the mains rather than the grid frequency, then the signal you capture needs to be at least as broadband as the noise in which you are interested. Since I do not use the actual local mains zero crossings for anything (other than electronically switching loads on at zero voltage and off at zero current, where absolute timing is irrelevant), I'm not sure why one might be interested in characterizing them. OTOH, since I do have equipment that responds to the grid frequency, I can see practical utility in characterizing that. Hence my suggestion to filter. Best regards, Charles
Re: [time-nuts] Mains frequency (Tom Van Baak)
Tom - I just had to comment--- Both assume some reasonable limit of mains df/f/dt. You can either do it with a fancy $100 to $1000 reference signal generator + PLL or FLL + IQ detector + professional box -- or with a $1 PIC and $0 s/w. /tvb You are of course correct. However I would most humbly point out that the cost of software is not zero if the time-nutter places any value on his or her time. If you figure your engineering direct labor rate is, for example $ 40 per hour, and the job takes 15 hours to program - you just blew $ 600 of your life. That assumes no issues crop up. Now as a private consultant or as a business that direct labor will be burdened with say about 130% overhead. So we are talking real money in terms of the value of your time. As a hobbyist you can contribute the time for free - but do under appreciate its value. For an olde hardware guy like me (who can sorta program a PIC) a known harware approach causes me less fear and feeling of dread than the PIC approach. So we do what we are more comfortable with. Enjoyable discussion though. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Choke Ring Antenna - Patch Placement? (Bob Stewart)
Howdy Bob - Hi John, I don't have LH here.? I've never looked into it.? Will it work with an NMEA GPS receiver? Bob - AE6RV My error. The T-bolt and LH combination is so common I just assumed you were using a T-bolt. As to your receiver, I do not know. Perhaps someone else on the list knows. If you can come up with a T-bolt, even to borrow, LH is a free download. In the survey mode it gives a nice map of levels vs elevations and azimuth. Hopefully you are having a lot of fun with this project. However my experience as a RF/Microwave guy argues that without a real antenna range and some standard gain antennas most of your data will be inconclusive if not down right maddening. The ground bounce is significant. This is why the amateur microwave guys often put one end of an outdoor range right on the ground. I did some gain measurements on an axial mode (i.e. end fire) helix for 2.4 GHz a couple of years ago. With both antennas at 4 ft above the grass moving one of them up or down a few inches changed the received level several dB. So I ended up with the Tx end on the grass. Much better. Most receivers have an elevation mask parameter that you can set. It throws out any data when a sat gets below the mask setting. This gets you most of the benefits of the choke ring, though I am sure for the super serious time nut there is some advantage to the choke ring. GPS is a fairly robust system design and will provide very good performance with some pretty shabby setups. However it is all a matter of your requirements as to when enuf is enuf! -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Choke Ring Antenna - Patch Placement? (Bob Stewart)
You might want measure the antenna pattern. Lady Heather has a mode that plots satellite signal level vs azimuth and elevation. You might want to try that. It takes a day or so to get a complete plot, but you have some hard data to compare various choke positions. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Re; Req: Decent GPS Antenna Active/PassiveRecommendation
At least for the T-bolt moving the antenna to a super-optimal location is a super waste of effort and money. I suspect this applies to most other GPS DOs. Unless you can compare the phase of the 10 MHz with a local Rb or Cs (or a good crystal) you cannot learn much more or provide better than the short term accuracy of the receiver. Improving on this will require a good local standard running open loop. The location should provide tracking of a few satellites - more than 4 if possible - but it will remain locked with as few as 1 or 2. The glitches you see will always occur as the receiver switches satellites and cannot be avoided with even the most perfect antenna location. So the short term ADEV presented by LH jumps around. Fooling around with the damping factor and time constants will not help this much. Set the DF to 1 and the TC to 200 seconds and leave it there. (or something like those values) The way to get a good standard is to open loop (using you fingers) adjust a local Rb such as the LPRO so it maintains a constant phase difference with the GPS 10 MHz for a period of hours. Using the time for the phase to change a measured number of nanoseconds, the frequency offset between the two is easily calculated. There is a HP ap note on how to do this. Use the GPS calibrated local open loop standard for all critical work - not the GPS output. Due to lightning considerations here is Kansas - my GPS antenna is in the front yard at 6 ft elevation and the N.E FOV is shielded by a 3 story house. Result is that the phase as plotted on a strip chart recorder is unchanging for hours relative to my Rb, but the flat plot shows phase jumps from time to time when the receiver shifts satellites. However the long term phase jump always returns to the previous value after the jump. To make further progress you need a good open loop local standard like the LPRO and some way to measure the 10 MHz Phase difference and record it over a period of hours. As to using the pps - I don't know much about doing it that way - however it seems obvious that the 10 MHz phase is more sensitive and faster due to the greater update rate. I could be wrong! Best regards and don't put the thing on the tower. Total waste of effort. Get a Rb. Do protect the receiver from rapid temp changes - -73 john k61ql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Display
It has been my pleasure to own and operate the VK4GHZ Thunderbolt display for several months. It works good, does what is should and I am totally pleased with it. It was easily installed and operated from the get go. If I did not have one I would have appreciated being notified of the of such a product via this list so I could buy it. It has been my good fortune to be Chief Engineer or VP of engineering for a number of RF organizations prior to my retirement. As such one must estimate and then defend to management, customers or the government, the non-recurring engineering costs for every project. So I can say with some confidence, rotary switches or not, this device required several hundred hours of design time for which the designer will never recover the true cost unless he values his time at 8 cents an hour. So a hearty well done to VK4GHZ from this old engineer. Further despite the pompous pretense of High SNR I see things a bit different - 1. Many are too lazy to delete the previous emails when commenting - resulting infinitely redundant repetition of previous comments. So much for not wasting bandwidth. 2. There is a tendency to hammer someone to death for being off topic. So what, I cannot see that the on topic stuff is all that vital to the good of mankind. Interesting, and invaluable sometimes, but if the space wasted by the practices noted in item 1 were devoted to some of stuff judged off topic - this list would be a lot more interesting. An example was the never-ending discussion of RS-232 a couple of weeks back. I believe that every possible mickey-mouse way to not do an RS-232 interface properly was floated. Yet this is on topic. I even noted that one person - who most of us respect - manged to volunteer the notion that no one should use RS-232 now days. Hunh?? Why not? It works and the USB disadvantaged such as myself manage to get by with it while implementing our projects. So it is my view that a number of members of this group could use a large injection of common courtesy, and should not be so critical of the efforts of others. After all, it is a hobby. -73 john K6IQL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Good (cheap) PIC chip choice for project?
Nice topic. I learned at bit. One source of info on the PIC is a course book and programming kit, programmer, prototype board and components set up by the ARRL. www.arrl.org You get all the stuff you need to get going. Software and a integrated development environment is provided. All in one package. They also have a couple of new courses on the Raspberry PI and the Arduino. I got into the PIC course last summer, read the extensive course book and learned to program the things. Made lights blink - also made LCD say Hi Hottie to my wife. My only comments - 1. Nice course for a beginner - my roots are old and in BASIC and FORTRAN Still used today, on junker laptops. So it was fun go fool with assembly for while. 2. My impression is that the PICs are powerful if you do a lot with one, but there is a lot of work involved to get up the learning curve. 3. My conclusion is that my next venture - should it occur will be with an integrated product that I can program in high level, with good input and some display capability, because I just want to get on with the project, but then I am not making a production device. Others comments re the more complex boards appreciated and noted for future reference. -73 john k6iql - ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OCXO shock protection
Re: [time-nuts] OCXO shock protection Water heaters must be bolted to the wall studs. Other wise they go over. Several hundred pounds of water is a big mass. Lived there for 50 years. Generally earthquakes are pretty localized and not a huge hazard with just a little thought. You do have to buy earthquake insurance. Costs me about $ 400 per year for a home I still have there. You can suspend the gear on as a pendulum from a single line. That should provide some isolation and also a DIY seismograph. The military shock mount racks are designed to protect a specific load. So may not work. john k6iql - in KS. New place different hazards! -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sun, May 19, 2013 10:13 pm Subject: time-nuts Digest, Vol 106, Issue 94 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Net4501's cheap.. (Tom Clifton) 2. Re: Time Nut Pickens at the MIT Flea ? (Bob Bownes) 3. OCXO shock protection (Perry Sandeen) 4. Re: Time Nut Pickens at the MIT Flea ? (paul swed) 5. Re: OCXO shock protection (Hal Murray) 6. Re: OCXO shock protection (Frederick Bray) 7. Re: OCXO shock protection (Chris Albertson) -- Message: 1 Date: Sun, 19 May 2013 19:10:22 -0700 (PDT) From: Tom Clifton kc0...@yahoo.com To: time-nuts@febo.com time-nuts@febo.com Subject: Re: [time-nuts] Net4501's cheap.. Message-ID: 1369015822.8519.yahoomail...@web161602.mail.bf1.yahoo.com Content-Type: text/plain; charset=iso-8859-1 Seller obviously figured out that somebody feels they are of value and adjusted the selling price to see what he can squeeze out of them. ?I'd suggest making a $20 offer if you want to try to drive the price back down to what is reasonable Message: 6 Date: Sun, 19 May 2013 18:07:51 -0500 From: Didier Juges shali...@gmail.com To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Net4501's cheap... I snatched one for $20 and they are now $59 or best offer. -- Message: 2 Date: Sun, 19 May 2013 22:09:06 -0400 From: Bob Bownes bow...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Time Nut Pickens at the MIT Flea ? Message-ID: 5b6c53a6-7b8c-47b2-8eb8-94a67f626...@gmail.com Content-Type: text/plain; charset=us-ascii We should plan a Time-Nuts BOF lunch after the next flea. Saw little TN gear @ Dayton save one Efretom RBI time base for $1800 and a few 10811s of dubious quality for $50 ea. the dents put me off gambling on one since I was given or the afternoon before! ;) On May 19, 2013, at 21:50, paul swed paulsw...@gmail.com wrote: Hello to the group. I did see the leitch video DA's. Was a good price if the DA's were in the case. The other thing to watch out for is that Leitch made all types of DAs digital also. You want the simple vide monitoring DA, Equalizing DAs are OK also delays are a pain. John it was good to see you and Jim. Great Wx. As for the pickens not much at all. I picked up to EGG RB oscillators and warming one up right now to see if it will work. At $20 each worth a try. Other then that parts and the real find a HPIB frame for Tek modules for $20. Been looking for one for quite a while. But really little time-nuttery stuff. Stan one day one way or another would be good to run into you. I also did not see Paul. (The other one who is also a slight time nut) Regards Paul On Sun, May 19, 2013 at 6:55 PM, Andy Bardagjy a...@bardagjy.com wrote: I grabbed a real nice Leitech distribution amplifier - but I took it home and it was empty! I walked back and returned it for a refund, but the seller said he had a whole stack in his office. I was gonna post to the list when I sort it out - it was a real bargin, and he said he might be willing to ship them around. Andy Bardagjy bardagjy.com On Sun, May 19, 2013 at 4:42 PM, Stan, W1LE stanw...@verizon.net wrote: Anyone got any Time Nut quality items at the MIT fleamarket today ? Stan, W1LE Cape Cod __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the
[time-nuts] Ground loops in measurements?
Attila Kinali One effective and sure fire way to deal with ground loops is to use a minature 1:1 50 or 200 ohm (not critical as most instruments are not matched inputs anyway ) in the line from your distribution amplifier to the driven device. Coilcraft has these for both PC and SMT Just drive one side with the source coax and connect the load to the other. They are about a 1/2 inch cube and the PC mount types have leads to which the coax can be simply soldered, or you can get fancy and put in a box with ground isolated connectors. The band width of these devices is typically 1 to 100 MHz or more. Eliminates all 60 Hz transmission that is common mode on the coax. These are not expensive. www.coilcraft.com. They did sell on the web for me about a year ago. -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Mon, May 20, 2013 10:28 am Subject: time-nuts Digest, Vol 106, Issue 97 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Time Nut Pickens at the MIT Flea ? (J. Forster) 2. Re: time transfer over USB (Jim Lux) 3. Re: Time Nut Pickens at the MIT Flea ? (Tom Van Baak) 4. Re: time transfer over USB (li...@lazygranch.com) 5. Re: Ground loops in measurements? (Volker Esper) 6. Re: OCXO shock protection (Tom Van Baak) 7. Re: time transfer over USB (Attila Kinali) 8. Re: OCXO shock protection (Attila Kinali) -- Message: 1 Date: Mon, 20 May 2013 05:50:07 -0700 (PDT) From: J. Forster j...@quikus.com To: Andy Bardagjy a...@bardagjy.com Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Time Nut Pickens at the MIT Flea ? Message-ID: 56273.12.226.214.5.1369054207.squir...@popaccts.quikus.com Content-Type: text/plain;charset=iso-8859-1 IMO, it would be good to have any gathering place w/in easy walking distance of the flea. Parking in Cambridge is not easy in the best of times. YMMV, -John = Plenty of good stuff in the area; Flour, Area Four, Catalyst, Friendly Toast, Blue Room, CBC, and so on. I live in the area - recent MIT graduate - and would be happy to set something up (though I think my gf's birthday is that day, so maybe not) Andy Bardagjy bardagjy.com On Mon, May 20, 2013 at 8:34 AM, J. Forster j...@quikus.com wrote: There are cafe/pizza options in the Strattion Student Center, although seating is somewhat limited. But there are other places in the same building. It's a short walk from the flea site (Mass Ave at Vasser Street) Bldg W-20 -John I was there as well, but did not see much of interest. That might be because Paul Swed scooped up the good stuff before I could finish the first pass :) Nice find Paul, hope they settle down for you. Would love to see a post-flea get together and put some faces with names, but I don't know of any places nearby. Paul - K9MR On May 19, 2013, at 10:22 PM, paul swed wrote: Good news at least the first EGG RB fired up and after adjusting the synthesizer is locked very nicely. Letting it bake and figuring out the dip switches. They were wrong or purposely offset. Hard to say. Lamp voltage is 12 VDC I suspect thats quite a good number if compared to the old FRS and FRCs I have down in the 5-6V range. The FRS/C run 12 new. Can't really find any documentation, but expected that. Regards Paul WB8TSL On Sun, May 19, 2013 at 10:09 PM, Bob Bownes bow...@gmail.com wrote: We should plan a Time-Nuts BOF lunch after the next flea. Saw little TN gear @ Dayton save one Efretom RBI time base for $1800 and a few 10811s of dubious quality for $50 ea. the dents put me off gambling on one since I was given or the afternoon before! ;) On May 19, 2013, at 21:50, paul swed paulsw...@gmail.com wrote: ___ 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. -- Message: 2 Date: Mon, 20 May 2013 06:14:12 -0700 From: Jim Lux jim...@earthlink.net To:
Re: [time-nuts] 10Mhz Sine from Square Wave Synthesizer
Andy - Glad to be of some small help. A couple of remarks re your comments John, thanks for your input, you reminded me that LFP performance often depends on source impedance. To the MMIC amplifier, you'd be amazed what you can do with an opamp these days. I was amazed reading the datasheet for the LTC6409 a 10GHz GBW, 1.1nV/sqrt(hz) fully differential opamp. With a gain of one, the frequency response is totally flat out to 1GHz. No actually I would not. I suggested the RF MMIC like one of the Mini-Circuits types because they have enough gain to recover the insertion loss of the input pad and the filter. They are also stable as a house not located in California. That leaves some gain margin for you to pad the output down to the desired level or to split it. As for the super duper chips methinks it is best to use no more performance capability than you need. Other wise you end up fighting oscillations, termination issues, and the necessity for very specific layout techniques. The hottest device is not always easiest to apply. Actually a 2N in common emitter will give more than 20 dB of gain and 100 mW out at 10 MHz and no microwave stability issues. It is just a matter of what is easiest for you to design and implement. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 10 MHz Sine form Sqaure Wave Synthesizer
For Andy - It is far easier in terms of bandwidth and power required to distribute sine waves, and that is the method most used. The sine wave is more easily transported via coax for long distances with no distortion issues. I suggest you terminate the output of your oscillator in a nice 6 dB pad to set the load impedance and to set the source seen by the next stage to around 50 Ohms. The next stage should be a low pass filter of about 4 poles with a cutoff at about 12-15 MHz. That will clean up the square wave and get you a good looking sine wave without much harmonic content and no critical tuning to set it up. Then follow that with an amplifier to get the level up and to drive the various loads. This is not the only architecture, but it will preserve the basic short term stability of your source. A PLL based scheme can either improve it or make it worse depending upon the design of the PLL and the VCO employed. You would still need a filter to clean up and filter VCO harmonics (if they exist) and the output buffer amplifier. Various MMIC chips exist that can amplify a 50 OHM source and drive a 50 OHM load with outputs up to 20 dBm and gains of up to 19 dB. These are untuned and work from 1 MHz up to several GHZ. -john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sun, May 19, 2013 8:15 pm Subject: time-nuts Digest, Vol 106, Issue 92 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Trimble Acutime Gold PPS (Miguel Barbosa Gon?alves) 2. Re: Time Nut Pickens at the MIT Flea ? (J. Forster) 3. Re: Time Nut Pickens at the MIT Flea ? (Andy Bardagjy) 4. Re: OCXO Adjustment Question (Azelio Boriani) 5. 10Mhz Sine from Square Wave Synthesizer (Andy Bardagjy) 6. Re: Net4501's cheap... (Didier Juges) 7. Re: OCXO Adjustment Question (Frederick Bray) 8. Ovenaire OCXO -- Final Diagnosis Summary (Frederick Bray) -- Message: 1 Date: Sun, 19 May 2013 22:54:39 +0100 From: Miguel Barbosa Gon?alves m...@mbg.pt To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Trimble Acutime Gold PPS Message-ID: -6084039917996433135@unknownmsgid Content-Type: text/plain; charset=ISO-8859-1 No dia 19/05/2013, ?s 22:44, Mike S mi...@flatsurface.com escreveu: On 5/19/2013 5:03 PM, Miguel Barbosa Gon?alves wrote: - Port A (T+) to R+ on the converter - Port A (T-) to R- on the converter - PPS+ to T+ on the converter - PPS- to T- on the converter On the RS232 part of the converter - TXD (pin 3) to computer pin 1 (DCD) - RXD (pin 2)to computer pin 2 (RXD) - GND (pin 5)to computer pin 5 (GND) I can see the serial time code on the computer yet the PPS (a long 400 ms one) doesn't seem to reach the computer. You're trying to have two different signals sourced on the 422 side converted to 232 outputs. That converter is bidirectional, it converts one signal from 422 to 232, and another from 232 to 422. Your PPS signal is going into an output on the converter. Hi!! I suspected that this could be the case. I think I'll build the converter whose schematic I posted previously. I will be entertained for a few days for sure. Thanks for your help! Regards, Miguel -- Message: 2 Date: Sun, 19 May 2013 15:05:58 -0700 (PDT) From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Time Nut Pickens at the MIT Flea ? Message-ID: 12375.12.226.214.5.1369001158.squir...@popaccts.quikus.com Content-Type: text/plain;charset=iso-8859-1 Not me. IMO, the pickings were pretty slim. I think a number of ventors opted for Dayton. -John == Anyone got any Time Nut quality items at the MIT fleamarket today ? Stan, W1LE Cape Cod ___ 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. -- Message: 3 Date: Sun, 19 May 2013 18:55:13 -0400 From: Andy Bardagjy a...@bardagjy.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Time Nut Pickens at the MIT Flea ? Message-ID: CA+hd4YjLkcdYKBfuCjN1Q1Y=nbbvbt0x-9ush-fwr-xpxpg...@mail.gmail.com
[time-nuts] Courtesy and Common Interests
Re: [time-nuts] S743 Marketplace Fariness Act And again, this thread has no business being on this list so please make it go away guys. The only reason I'm saying anything is to encourage people to just stop! -Bob Really Well I am not so sure about that. In response to a query to the group regarding a possible eBay message as coming from a hacker - I took the trouble and provided an answer that correctly illuminated the issue. Further since a good deal of the equipment we use comes from on-line purchases, both eBay and distributors, as well as private sales; I submit that this topic can potentially impact our hobby to some extent. It may drive some sources out of business. At this point who knows; as the bill has not yet become law. So I believe that some members may wish to weigh in on the topic with their representatives - but to do so they have to know that the issue exists. Since it may be of concern to some time-nuts I maintain that it is appropriate. I do not contribute often here, but when I do it is usually from my 44 years as a microwave engineer who did spread spectrum timing for the military years before GPS was even thought of. So now and then I just may have a useful idea that could benefit the topic at hand. Mostly my inputs are never acknowledged by as much as a simple thank you. The above is just one example of how unfriendly and discourteous this list can be. Who the hell cares if few bytes of text are a bit off topic? And who is to say that no-one can benefit from it. Lets lighten up a bit. -john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] S743 Marketplace Fariness Act
The ebay message re this law is probably legit. In any case the congress IS considering such a law. In essence it forces all internet sellers to collect the sales tax due in the buyers state. If you live in a state with a law requiring that sales tax be paid on all out of state purchases (internet or not), often called a use tax, as the buyer you are required to pay this tax. The taxes already are on the books, they are often not enforced. You can learn all about this with a Google search which will reveal all sorts of opinions. Here is one that is not too bad: http://www.forbes.com/sites/beltway/2013/04/23/five-things-you-should-know-about-the-long-overdue-online-sales-tax-bill/ If you already comply with the law and do a lot of internet purchases; passage will relieve you of a pain in the ass accounting job at tax time. If your state has no such tax or if you avoid paying it, though your state requires it, passage will cost you some sale taxes you would have otherwise escaped. One nasty consequence is that the software to pull this off is non-trivial since local sales taxes in many states vary by county, school district, local bond issues and so on. How that is handled should be amusing. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 10 MHz clock distribution for the lab
Just a couple of comments from a RF guy and FMT-nut 10 MHz clock distribution for the lab In the small coax cables one might consider RG-223. This is a 1/4 inch more or less diameter cable that features two concentric braided shields. Each is a very dense weave and is silver plated. This a very high quality mil spec coax. the main drawback is that a normal BNC fitting will not pass the entire cable through the clamp nut or most of the shield through the hole in the internal ferrule. However, Pasternack, among others has the correct connectors for BNC, TNC, and type N. I have used this cable with good success to keep RF from radiating in test setup. It is way way better than even quality RG-58. I found part of a reel on eBay for next to nothing. How many instruments? Some time ago I surveyed a number of instruments to determine how many had an actual 50 OHM input for the 10 MHz reference. Answer - some do, most don't, though many specify something like 1V rms from a 50 Ohm source. I have been able to operate 1 spectrum analyzer, 2 Fluke synthesizers, A hp synthesizer, and a HP 5345 counter all at the same time from a LPRO RB source using Ts and only terminating at the end of the line. Actually the termination had no effect as I was not looking at phase. Most of these devices seem to present a relatively high Z load and as long as that is the case; the simple T scheme is OK as long as there are not too many and the distances between them are short in terms of wavelength. It is easy enough to crudely determine the input Z using a series 1 K resistor on the source side.and just measuring the voltage drop with a scope. I did get a distribution amp as things got more complex around here, but I never had a problem with the simpler scheme either. -john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] haet shrink tubing
For those wanting a moisture sealed heat shrink tubing, McMaster-Carr has many varieties of heat shrink tubing materials, both thick and thin walled. Several types have an internal adhesive that melts when the heat gun is applied. I have used this stuff on coax connectors for years and it works quite well. You can get it in large diameters and in various decorator colors. www.mcmaster.com and search for heat shrink. best regards john c roos K6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB Clocks don't sync anymore (revisited) (J. Forster)
Re: WWVB Clocks don't sync anymore (revisited) (J. Forster) As it turns out the batteries in my Radio Shack WWVB alarm clock had died. I replaced them last night around midnight and went off to bed. This morning it has synched up fine. I dissected an identical one of these a while back. It does have a very narrow band single resonator crystal filter. I think the BW was just s few Hz and PSK would turn to AM at the keying rate. Of course on each phase reversal the amplitude out of the filter would go to zero for an instant. Here in East Kansas the WWVB signal from a ferrite rod can be received on my tek 475 with no premap. That is loud. -73 john K6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Wed, Mar 20, 2013 12:29 pm Subject: time-nuts Digest, Vol 104, Issue 70 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: WWVB Clocks don't sync anymore (revisited) (J. Forster) 2. Re: WWVB Clocks don't sync anymore (revisited) (J. Forster) 3. Re: Repair of PRS10 Lamp Assembly (Dr. G?tz Romahn) 4. Re: WWVB Clocks don't sync anymore (revisited) (Clint Turner) 5. Re: Is possible precise 1pps? (Herbert Poetzl) -- Message: 1 Date: Wed, 20 Mar 2013 09:24:12 -0700 (PDT) From: J. Forster j...@quikus.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] WWVB Clocks don't sync anymore (revisited) Message-ID: 65101.12.6.201.31.1363796652.squir...@popaccts.quikus.com Content-Type: text/plain;charset=iso-8859-1 Have you tried to put BPSK through a narrow band filter and looked at the envelope at the output? -John == Hi Also consider that some of these receivers use a narrowband crystal filter in front of the IC. I doubt they spend a ton of money on the components, so that may not be the world's best crystal in terms of aging. If it ages far enough the receiver simply goes deaf. If it ages a bit less than that, it slices off one sideband much more than the other. That's likely to do all sorts of odd things to it's ability to ignore phase modulation. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Herbert Poetzl Sent: Wednesday, March 20, 2013 10:58 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWVB Clocks don't sync anymore (revisited) On Wed, Mar 20, 2013 at 02:34:19AM -0400, Bill S wrote: Interestingly, I have three timepieces that will no longer synch to wwvb.Two Radio Shack digital clocks and a Casio wristwatch that I've worn for a couple of years and was always pretty much dead on. Like Paul, I have an analog Lacrosse clock that is running correctly. Nothing I've tried will make the other clocks synch. Maybe this is related to the phase modulation time code protocol used by WWVB since October 29th, 2012. Their website also states that clocks using information from the carrier will no longer work, and that during the transition period (at least March 21st 2013), the PM signal will be turned for for 30 minutes twice a day (noon and midnight MST) so maybe check if the clocks sync then? best, Herbert http://www.nist.gov/pml/div688/grp40/wwvb.cfm Bill_S W2FMA On 3/19/2013 5:29 PM, paul swed wrote: Funny you bring this up. I am just noticing a sharp clock that I always use and it has been accurate. But it did not flip with the time change this time and though it says its locked its off by 45 seconds slow. Yet a lacross clock across the room seems to be on second wise but never flipped with the time change. As I say its just becoming apparent. Regards Paul WB8TSL On Tue, Mar 19, 2013 at 4:55 PM, Clint Turner tur...@ussc.com wrote: A few weeks ago I posted a question/comment about some of my WWVB-based Atomic clocks no longer setting themselves properly. These two clocks, SkyScan #86716, would show the symbol indicating that they had set themselves, but their time was drifting away from UTC. Interestingly, they *would* set themselves exactly once upon installation of the battery, but never again. Since that time, I've done a bit of digging around. The first suspicion was that, perhaps, the NIST had fudged a bit in the WWVB timecode recently, so I manually decoded a few frames and analyzed them: Nothing suspicious there. The next question was if the
Re: [time-nuts] Don't use cheap cables -- a cautionary tale
I could not agree more, having been burned once or twice. One batch of 50 Ohm cables was clearly marked 75 Ohms when received. These used some form of relatively high resistance foil shield and a drain wire for the outer conductor. The high resistance permitted a ground loop with hum on my 10 MHz reference thus FMing my signal generator. A couple of things to note: Measure the DC resistance between the connector bodies it should be way less than 1 Ohm, perhaps 0.1 ohm above what you see with the probes shorted. The previous regarding RG-58 apply unless the cable is labeled with a manufacturers part number and that is stated in the vendors spec - Such as BELDEN 8262 RG-58U Coaxial BNC M/M Patch Cable 10FT. RG58 C/U MIL C17 50 OHMS stamped on the cable. These were from - Digital Connections - cablesellforl...@yahoo.com and purchased via eBay. The price was very reasonable. Testing with a HP ANA showed very low VSWR and the expected insertion loss up to 1 GHz. Shield resistance was very low, as expected. I have used these in lengths from 3 ft to 20 ft with no difficulty. The key here is the Belden part number in the vendors ad that can be checked to see what you are getting. The MIL SPEC and RG58 etc was stamped on the cables when received. For outstanding performance use RG-223 which is slightly larger than RG-58 and is a 50 Ohm cable having a very dense double sliver plated braid shield. You can buy these made up for a small fortune or buy an odd lot of RG-223 on eBay and make your own. Pasternak has the connectors with the appropriate diameter nuts and collars. The connectors for Rg-58 are had to make work on RG-223. Connectors for Type N and SMA are also available. Installing clamp style connectors on RG-223 requires a certain amount of passion (and a stainless steel welders tooth brush to comb the braid) but hey, no pain no gain. -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sun, Mar 3, 2013 11:00 am Subject: time-nuts Digest, Vol 104, Issue 13 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Don't use cheap cables -- a cautionary tale (Bob Camp) 2. Re: webcam app to watch for and time stamp changes (Magnus Danielson) 3. Re: Don't use cheap cables -- a cautionary tale (John Ackermann) 4. Re: Don't use cheap cables -- a cautionary tale (Kevin Rosenberg) 5. Re: Don't use cheap cables -- a cautionary tale (Bob Camp) 6. Re: Don't use cheap cables -- a cautionary tale (Jim Lux) 7. Re: webcam app to watch for and time stamp changes (cfo) -- Message: 1 Date: Sun, 3 Mar 2013 10:10:38 -0500 From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale Message-ID: 335213bf-bbf3-44bd-9a7a-0bd481028...@rtty.us Content-Type: text/plain; charset=iso-8859-1 Hi By any chance is the connector a BNC? They have been known to create similar looking issues. Bob On Mar 3, 2013, at 9:59 AM, John Ackermann j...@febo.com wrote: I was measuring two OCXO and was getting some quite unusual results -- a symmetrical frequency cycling of several more than 1e11 p-p, with a period of around 15 seconds. I removed an RG-58 3 foot jumper cable that fed 5 MHz from the rear panel of another OCXO to a patch panel (where it was terminated in 50 ohms), and the noise quieted right down. See the attached frequency plot. The other OXCO had a similar jumper cable in the path, and although the two cables were not parallel to each other for any significant distance, there was still enough signal radiation and pickup to cause a nasty problem. Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. John austron-fts-beat-note.png___ 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. -- Message: 2 Date: Sun, 03 Mar 2013 16:29:15 +0100 From: Magnus Danielson mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] webcam app to watch for and time stamp changes Message-ID: 51336c4b.4030...@rubidium.dyndns.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed On
Re: [time-nuts] question for expert time guys (Hal Murray)
Hello Hal - I spent a lot of my RF engineering career in related areas, including radar, EW, and spread spectrum timing systems. Since the distance is short and the cost is an issue you may wish to consider an analog system solution. Specifically your master station transmits a RF signal that is FM modulated with a high frequency tone. The remote unit is a transponder. It receives the tone and re-transmits back on another frequency. Almost no parts required. At the master station the phases of the outgoing and returning tones are compared. The distance is directly proportional to the phase shift between the outgoing and incoming tones. For instance if the tone is 10 MHz the 360 degrees of phase is 100 nS which is about 100 ft round trip. The phase may be measured either analog and A/D converted or digitally and in either case is then easily converted to range by your processor. By adjusting the tone frequency you can set the full scale range. To increase resolution higher frequency tones may be used. To overcome ambiguity when the range goes beyond 360 degrees of phase, add a lower frequency tone to resolve the ambiguity. This scheme has been used in surveying instruments (the Teleurometer) and even an ill fated German bombing system in WWI. The latter proved delightfully easy to jam since the Brits had a spare TV transmitter in the correct band. Look up something like tone ranging. -john c roos k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Fri, Feb 1, 2013 4:24 am Subject: time-nuts Digest, Vol 103, Issue 2 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Loran again (Stan, W1LE) 2. question for expert time guys (Rick Harold) 3. Re: Low noise power supplies? (gary) 4. Re: Low noise power supplies? (John Miles) 5. Re: question for expert time guys (Hal Murray) 6. Re: question for expert time guys (Azelio Boriani) -- Message: 1 Date: Fri, 01 Feb 2013 00:30:40 -0500 From: Stan, W1LE stanw...@verizon.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Loran again Message-ID: 510b5300.8000...@verizon.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed Fired up the SRS FS700 and auto found the GRI 89700 microsecond stations in Dana Il (master) and Seneca NY, (slave) both with equal signal strength of 63 db. Other slaves were not to be found. Noise margin of 32 dB and Rx gain of 72dB. So the Rx is all locked up. Tomorrow I will have more data comparing the 10 MHz from the T'Bolt. Right now they are comparing to within 10EE10. Stan, W1LE Cape Cod On 1/31/2013 10:44 PM, Stan, W1LE wrote: What GRI should we be listening for ? Stan, W1LECape Cod FN41sr On 1/31/2013 9:56 PM, paul swed wrote: Rich indeed its on the air. Warming up the FS700 to see if it will lock. Have a pattern ram thats getting flakey and takes about 30 minutes to warm up along with the oven. ___ 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. -- Message: 2 Date: Thu, 31 Jan 2013 22:37:00 -0600 From: Rick Harold rickhar...@gmail.com To: time-nuts@febo.com Subject: [time-nuts] question for expert time guys Message-ID: CAODR2TDuMSpOr8JYvjMm-QRnRhM8sxYGkY=vrn6yttk5t3t...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 To time experts/EE's. I would like to triangulate a position of a device which moves using 3 fixed positions devices of known location. The idea is to have these operate on 915mhz or 434mhz or 2.4ghz or appropriate frequency. These two type of devices (fixed and mobile) are all under my control and thus customized as needed. The mobile device (not a phone, custom device) would be the least expensive item. I'd like a range of 150 feet or better and accuracy of 3 feet or better. When manufactured these items they can be calibrated in order to adjust for any variation in IC's, discrete components etc... We can assume for now the temperature is constant 70 degree temperature. Cost is the key design factor. The general flow is: 1. base station 1 indicates we are determining position of device A. 2. Each base station 1, 2, 3 take turns pinging the device to determine distance.
Re: [time-nuts] Better gps antennas than a Symmetricom 58532A
Just a few comments on the cable and VSWR business. The short version is that unless the run is longer than 100 Ft any antenna with a preamp gain of more than 30 dB will probably do and the VSWR business does not matter at all unless it is truly terrible. For example the loss due to mismatch for various VSWRS is as follows VSWR Mismatch Loss 1.5 0.2 dB 2.0 0.5 dB 3.0 1.2 dB 4.0 1.9 dB Source Microwave Engineer's Handbook 1968 Cable Loss is a consideration for long runs. All data at 1.5 GHz. Cable Loss / 100 Ft RG-614 dB RG-8/RG313 5.8 dB Andrew Cable - Superflex Heliax 1/4 inch Heliax 7.47 dB 3/8 inch Heliax 5.12 dB Sources - Andrew Catalog, ITT Reference Data for Radio Engineers Now you have to consider the effect on the VSWR at one end of the cable at the other end. Here we define Return Loss as the round trip loss of the cable if the far end is SHORTED. That is an infinite VSWR with 100% reflected power. This is Twice the 1 - way loss. Return loss is just another expression for VSWR and one can be converted to the other - Thus Return Loss Equivalent VSWR at input 28 dB (RG-6 shorted) 1.05 to 1 14.4 dB(1/4 Heliax shorted) 1.5 to 1 11.6 dB (RG-213 shorted) 1.74 to 1 10.2 dB (3/8 Heliax shorted) 2.0 to 1 So we see that with 100 FT of very good cable, even a infinite VSWR at the far end produces a VSWR at the input end of 2 to 1 or less, resulting in a mismatch loss of 0.48 dB or less. This is why the T-bolt and other manufacturers state that the cable impedance simply does not matter. I did not treat the other consideration which is overall noise figure. This is because the receiver and antenna designers use such high gain pre-amplifiers in the antenna. If you follow this up on the Web you can find that with enough preamp gain (subtracting the cable loss)the effect of the cable and the noise figure of the second stage (the receiver) is totally swamped and the first stage noise figure is maintained. By the way in the basic noise figure equation the value for NF is an absolute number - it is not in db. The short version is that if you have a 30 dB preamp in the antenna and 10 dB of cable loss, you are still 20 db to the good. The noise figure is degraded by (crudely) 1/20 dB or roughly 1%. Obviously more preamp gain is better as is a shorter or better cable, but the basic system design assumes use of economic cable like RG-6. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 10 MHz - 16 MHz clock multiplier
Interesting problem Re: 10 MHz - 16 MHz clock multiplier What is low cost?? Serious question. john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Wed, Jan 2, 2013 9:19 pm Subject: time-nuts Digest, Vol 102, Issue 10 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: 10 MHz - 16 MHz clock multiplier (Didier Juges) 2. Re: An embedded NTP server (Tom Harris) 3. Re: An embedded NTP server (Jim Lux) 4. Re: An embedded NTP server (Michael Tharp) 5. Re: clock-block any need ? (Magnus Danielson) -- Message: 1 Date: Wed, 2 Jan 2013 19:31:52 -0600 From: Didier Juges shali...@gmail.com To: Tom Van Baak t...@leapsecond.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] 10 MHz - 16 MHz clock multiplier Message-ID: CAMQqFu=ghst14ygddgw8pvjrnmnryyfne13g06p+qrmv48a...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 Tom, This may not be the answer you are looking for, but the simplest way may be to use a uC that has a PLL for clock generation. Didier On Wed, Jan 2, 2013 at 12:54 PM, Tom Van Baak t...@leapsecond.com wrote: What's the simplest way to generate 16 MHz from 10 MHz? This will be for clocking a microcontroller at 16 MHz given 10 MHz (Cs/Rb/GPSDO). Low price and low parts count is a goal; jitter is not a concern but absolute long-term phase coherence is a must. The ICS525 (as in TAPR Clock-Block) is a good candidate but I was wondering if there's something cheaper, less functional, and maybe not SSOP. Any suggestions? Thanks, /tvb ___ 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. -- Message: 2 Date: Thu, 3 Jan 2013 12:34:15 +1100 From: Tom Harris celephi...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] An embedded NTP server Message-ID: cahjg12qxpb9px8dp6ngk-x575etnsfc+csqr6acsrx7gfw-...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 +1 for Forth! +1 for your opinions on PICs AVRs. We can buy low end NXP ARM Cortex M0 chips (e.g. LPC1113) for less than the PIC18 we were using before, and it has a real compiler and (unlike the real world) evidence of intelligent design! Do you really need an OS? Surely for a box that is only ever going to be an NTP server you just need a network interface and good maths? I've just seen a later comment where you mention floating point support, but would 64 bit integer maths work just as well? On 3 January 2013 06:25, Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Jan 2, 2013 at 11:16 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: I've given up on PIC and Atmel microcontrollers and their antiquated CPU designs. My life is too short to fight odd-ball compilers, when I can get a real 32 bit CPU and a good compiler instead. That is a valid point if you are building a one-off project. Your time is worth something. But if you plan to sell a million AA cell battery chargers using a 32-bit controller is uneconomical. These will always be a bigger market for 8-bit chips then for 32-bit chips. For an NTP server I'd go with something that can run an OS and the NTP reverence implementation. ARM (and others) can do that. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Tom Harris celephi...@gmail.com -- Message: 3 Date: Wed, 02 Jan 2013 18:26:24 -0800 From: Jim Lux jim...@earthlink.net To: time-nuts@febo.com Subject: Re: [time-nuts] An embedded NTP server Message-ID: 50e4ec50.1030...@earthlink.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 1/2/13 5:34 PM, Tom Harris wrote: +1 for Forth! +1 for your opinions on PICs AVRs. We can buy low end NXP ARM Cortex M0 chips (e.g. LPC1113) for less than the PIC18 we were using before, and it has a real compiler and (unlike the real world) evidence of intelligent design! Do you really need an OS? Surely for a box that is only ever
Re: [time-nuts] GPS DO Alternatives
Hello all - People talk about good deals on Thunderbolts but I have yet to see one. It seems peak Thunderbolt passed before I was seriously looking. I would suggest some more serious looking. This guy TRIMBLE GPS RECEIVER 10MHZ CLOCK THUNDERBOLT currently has more than 10 T-bolts for sale on eBay as of this morning for $ 175. Last summer I bought 3 of his units and all were in great condition and worked just fine. the one pictured and all of the ones I obtained had a nice MiniCircuits 2 way splitter that came with it. The splitter is about $ 50 new and usable at 10 MHz and over a wide bandwidth. In fact during the several days of lamenting the lack of T bolts there were several vendors offering them for various prices from good to not so good. As to building a GPS DO some of the recent comments from persons dedicated to precision time and frequency - apparently willing to go to extreme measure to achieve it seem curious to say the least. Here performance seemed to be unspecified and of less importance than what uP to use. As usual there was the temptation to jump to implementations without the steps essential to any good design to wit: 1. A agreed to requirements document 2. A peer reviewed specification 3. A conceptual design and conceptual packaging concepts (What should the box cost?) 4. A conceptual design review 5. A preliminary circuit design, SW design, and final package concept. 6. Implementation and test of the preliminary circuit and SW design. 7. Incorporation of the test results and final design release. Instead the discussion has centered on what microprocessor (of a hundred that would work) and how to eliminate glue logic and and a few analog parts to save money. This is silly - silicon is CHEAP. Major cost items not considered include - somewhat in order of decreasing cost : *The box you put it in - suspending it above the bench on inspirational thought probably will not work. A nice box is easily $ 50.00 so who cares about adding another flip flop or counter at 25 cents each. *The printed wiring board. Most costly per unit up to about 4 pieces * A power supply - you will need a good low noise one. * OCXO So when you look at the total system - any GPS DO when fully developed and packaged into a unit with long term reliability and performance acceptable to this group is a non-trivial project. It is, however a challenging and rewarding project - particularly if well done. -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Sat, Dec 8, 2012 2:56 am Subject: time-nuts Digest, Vol 101, Issue 63 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: GPSDO Alternatives - Bert's boards (WB6BNQ) 2. Re: PPS offset between GPS receivers (Chris Albertson) 3. Re: GPSDO Alternatives (David) 4. Re: PPS offset between GPS receivers (Bob Camp) 5. Re: Open source (Poul-Henning Kamp) 6. Re: Open source (David Kirkby) 7. Re: Termination talk (Attila Kinali) -- Message: 1 Date: Fri, 07 Dec 2012 18:06:17 -0800 From: WB6BNQ wb6...@cox.net To: Discussion of precise time and frequency measurement time-nuts@febo.com, ewkeh...@aol.com Subject: Re: [time-nuts] GPSDO Alternatives - Bert's boards Message-ID: 50c2a099.cbfda...@cox.net Content-Type: text/plain; charset=us-ascii Hello Bert, The boards look nice but tell me nothing of the circuitry. How about sending the schematics ?? That way I can appreciate what it is that you have. BillWB6BNQ p.s. By the way, what ever happen with that DMTD you were going to produce about three years ago ? ewkeh...@aol.com wrote: Attached is my latest ExpresPCB layout of a GPSDO. A clear understanding of the GPS limitations, a goal as to what I want to control ,focus on attainability, reproducibility KISS, cost and tests of partials on development boards and what you see if you download the ExpessPCB software is on the right the saw tooth correction, in the middle the analog board with opto isolation to prevent ground loop and on the right the actual GPSDO. This particular unit also allows you to link a 20 Hz offset FRS-C (part of my dual mixer) to my house reference. Total material cost depending how many boards one buys is below $ 40. I will include this particular board along with other designs on my next order and subsequently cut with a sheer. The board on the right could be
Re: [time-nuts] time-nuts Digest, Vol 101, Issue 40
Hello All - Just a quick comment from an olde RF engineer. Bob Camp wrote: Hi You might be surprised by the noise floor of an XOR run at 125 KHz. They are quite good at that low a frequency. Bob An XOR, unlike a mixer, does not have a null when the phases are in quadrature. This is the fundamental problem with using it as a phase detector. Rick A XOR does have a null of sorts - at quadrature the average DC level of the output is a 1/2 the supply voltage. For a DBM it is zero. The DBM in inherently quieter with noise figures of about 7 dB which is not the case of any XOR. Finally to avoid DC loading of the output of either type the DC level should be blocked by a capacitor of suitable value to pass the lowest frequency of interest. A 1 K or similar resistor on the IF port of the DBM will assure a known load and consistent output voltage. Finally a low pass LC filter should follow the capacitor to suppress the high level 2F output of the mixer and keep it out of the following circuitry. This is old hat to most I know. -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Wed, Dec 5, 2012 8:24 pm Subject: time-nuts Digest, Vol 101, Issue 40 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: Very challenging phase noise measurement, does anyone have an idea?? (John Miles) 2. Re: Very challenging phase noise measurement, does anyone have an idea?? (Bob Camp) 3. Re: Very challenging phase noise measurement, does anyone have an idea?? (Jim Lux) 4. Re: Very challenging phase noise measurement, does anyone have an idea?? (Bob Camp) 5. Re: Very challenging phase noise measurement, does anyone have an idea?? (Rick Karlquist) -- Message: 1 Date: Wed, 5 Dec 2012 17:24:00 -0800 From: John Miles jmi...@pop.net To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Subject: Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea?? Message-ID: 012801cdd350$5f8a5c80$1e9f1580$@pop.net Content-Type: text/plain; charset=us-ascii That would be a good way to do it. I wouldn't use an XOR gate or other digital phase detector for this, due to the low slew rate among other things. Instead, you could phase lock two of your sources with a double-balanced mixer, then run the IF through a lowpass filter and a quiet opamp or other LNA. The baseband noise can then be viewed on a spectrum analyzer that goes down to whatever the minimum offset of interest is. The analyzer's noise floor doesn't matter, it just needs to be something that can tune down to the 100 Hz-1 kHz area. An old-school HP 8566 or 8568 is ideal. For calibration details, see the references in the last FAQ entry at http://www.ke5fx.com/gpib/faq.htm , especially HP 11729B-1. Alternatively, I'm not sure where the noise floor of the FSUP is, but if it is otherwise low enough, you could mix the 125 kHz with an ultra-low-noise OCXO and measure one of the resulting sidebands. It might or might not be necessary to filter the other sideband depending on how the FSUP works. You could also build a low-noise 8x active multiplier to get to 1 MHz where the FSUP can see it, as well. This would have the advantage of not requiring a ULN OCXO for mixing, and would also boost the PN by 18 dB for easier measurement on the FSUP. However, you'd need to be careful with the multiplier's residual noise, especially in the first couple of stages. If you need to make these measurements over and over, go with the multiplier or mixer, otherwise I'd use an analog quadrature PLL. -- john Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Adrian Sent: Wednesday, December 05, 2012 4:40 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea?? You can always use an external mixer / phase detector and the baseband input of a HP 3048A or FSUP. Just to name a few: For low power (+7dBm) you can use a SRA-3 which goes from 25kHz to 200MHz SRA-3MH +13dBm from 25kHz to 200MHz SRA-3H +17dBm from 50kHz to 200MHz For high power signals use a RAY-3. It goes from 70kHz to 200MHz. The IF must be specified from DC, which for the above is the case. Between
Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? (Dale J. Robertson)
Dale - To your question re BPSK and DPSK. In both modes the phase shift is 180 degrees. Straight PSK has the issue of determining the 1's from the 0's, at the receiver as there is no phase reference. To avoid this DPSK encodes the the serial data stream prior to the bi-phase modulator. As I recall (at 1 AM) the method is like this. If the present bit to be sent is a 1 the phase of the carrier is inverted. If it is a zero the phase is not inverted. This is easily sorted out in the receiver using a flip flop and an XOR. However recovery of the carrier must occur before decoding of the data stream and is done the same way for both - at least in classical receivers. Squaring Loop or Costas Loop. -john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Factors other Than Antenna Splitters (Bob Camp)
Bob - Thanks you for your comments below. As others have reported, a TBolt in a good environment is closer to a 1 or 2 ns one sigma (over 100+ seconds) than to the numbers in the Trimble manual. The satellite data on the NIST site shows much better numbers than they show for Satellite Clock and Satellite orbit. That is encouraging. Trimble probably worst cased it to avoid issues. Good idea for a product. On further thought it occurred to me that that for purposes of comparison between receivers use of a single antenna reduces the number of variables. Thus the issue comes down to the effect of the presence of the second receiver - assuming that a passive splitter in a lab environment stays pretty well put. I think this can be proven by test easily enough. One simple experiment for the curious would be to observe the performance of one receiver (the UUT) with both connected to the splitter and then evaluate the change in performance with the second receiver under the following conditions. 1. disconnected and cable open circuited 2 disconnected and cable terminated - may required a DC block 3. disconnected and cable shorted - may require DC block Up until yesterday I had a setup for other tests that could do it easily, but I goofed and cleaned up the bench. best regards- john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Factors other Than Antenna Splitters
Hello All - The recent discussion on the use / not use of splitters affecting GPS timing performance may be further informed by this table. It was extracted from page 5-8 of the Thunderbolt Disciplined Clock User Guide Version 5.0 Part Number: 35326-30 November 2003 Table 5-1 GPS Error Sources Error Source 1 Standard Deviation 5 - 50 ns Atmospheric Models (Ionosphere) 5 - 50 ns Receiver noise (Multipath) 1 - 20 ns Satellite Clock Model 10 ns Satellite Orbit Model 5 ns Antenna Survey 1 ns Paragraph 5.2 on the same page indicates the timing between two sites to be +/-15 ns 3 sigma for the T-bolt My take on this as an old microwave guy and non-timing expert is that there are problems greater than splitter cross-talk and variations in cable propagation delay at least for simple systems using only L1. The more learned in these matters may be able to refine the above. For those interested in measuring splitter effects,please remember that no splitter will perform correctly unless terminated on ALL ports in its design impedance. This is especially true for isolation. - best regards john roos k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] To use or not to use transmission line splitters for GPS receivers
Hello All - I do not believe there is a hard Yes or No answer for this question. It depends upon the performance specification of the system elements and the system requirements. For instance if the leakage of noise and discrete signals from each receiver out of the antenna port combined with the port to port isolation of the power divider is below the level of harm to the associated receivers then the answer is yes. Otherwise NO. The issue of antenna power is simply solved by placing a DC block in the line from the splitter to all but one of the receivers. It then powers the antenna for all of them. I use this system with a 3 way splitter and 3 T bolts. More elaborate and redundant schemes are possible with a bit of engineering. I have several of the receivers developed by Novatel for the early WASS project experiments. These boxes used 3 receivers as both L1 and L2 were involved. A standard Mini Circuits power splitter was employed to feed the antenna to all 3. Apparently that sufficed for what was a pretty demanding requirement. Finally - Anyone advocating a hard Yes or No to this question without first considering the performance numbers for the system elements has been smoking their view-graphs. With proper design it is totally feasible to feed a number of receivers from one antenna. -john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Modulation and 10 MHz Delay Lock (Jim Lux) (Jim Lux)
for Jim Lux -- Thanks for the comments - Yes, if the receiver is linear (e.g. say you do a sliding code correlator and slide until you get the peak, with the correlator using a multiplier)... That is how the system I did worked. It could defeat an on-frequency jammer that was 20 db stronger than the signal while holding a 1e -6 BER. So considering the BPSK demod required a 10 db CNR, the total AJ processing gain was about 30 dB, which is what was expected. But since most (inexpensive) receivers have hard limiters/1 bit quantizers in front of the correlator, what goes into the correlator is a square wave at the jammer frequency, and you can slide your PN code all day and not get a peak. Yep - a hard limiter would kill any processing gain and simplify the design. There's some analysis out there that tells you how many bits you need for a given Jammer/Signal ratio, but in general, if the jammer is 20 dB over the signal, you need 3-4 bits. Back in the day, when bits were very expensive, that's why narrow band excisers were popular.. basically you'd run something like a PLL to recover the tone jammer, and subtract it out. We were not that good in 1976. But going above 20 GHz and antennas with a 2 degree beam width hid the signal and provided considerable immunity. Anyhow - thanks for the information on more modern techniques! -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Jammer
In considering the effect of a simple jammer on a GPS receiver, a simple link analysis is insufficient. What must also be considered is the anti-jam capability of the receiver which due to spread spectrum processing gain will reject any simple jamming signal even though is it 10's of dB stronger than the desired signal. 73 -john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Modulation and 10 MHz Delay Lock (Jim Lux)
Hi Jim - Thanks for the update on the modern GPS receivers. I was aware that the modern ones do not have a classical analog tracking loop, much less a bunch of them. However it is a useful concept for purposes of explanation that you do not need the 1 pps to lock up the 10 MHz VCXO - which was my main point. The Tbolt block diagram in the manual Figure 5-10 shows the 10 MHz VCXO output going to the receiver and also to the output. The 1 pps comes from the cpu and support circuit. While the diagram is clearly simplistic - it implies that the Receiver circuitry first locks up the 10 MHz oscillator and the the 1 pps is derived from that. My only point was that it is possible and perhaps even better to discipline an oscillator using a code correlator (however implemented) rather than steering using the 1 pps. I believe this is why the T bolts work so well. For one thing the loop should work better and faster if the input is at the chipping rate rather than at 1 pps as the information rate is higher. On doppler - I believe that since the spread spectrum sidebands are coherent with the suppressed carrier, their relationship to it is unchanged by doppler and thus it should be possible to achieve a code correlation on a doppler shifted signal. The recovered carrier would be shifted in frequency by the doppler but it would still be recovered - at least by a classical IF correlator. - On jamming - maybe so, but the effect of the receiving correlator is to spread the energy of a CW interferer and concentrate the energy of the signal with the matching PN modulation is it not good fun anyway! -73 john k6iql -Original Message- From: time-nuts-request time-nuts-requ...@febo.com To: time-nuts time-nuts@febo.com Sent: Tue, Oct 2, 2012 9:53 pm Subject: time-nuts Digest, Vol 99, Issue 19 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than Re: Contents of time-nuts digest... Today's Topics: 1. Re: GPS Modulation and 10 MHz Delay Lock (Jim Lux) 2. Re: GPS Jammer (Jim Lux) 3. Re: GPS Jammer (johncr...@aol.com) 4. Re: Best counter setting for ADEV? (Jim Lux) 5. Re: RFX GPSDO - Anybody played with one of these? (Jim Lux) 6. Centering ocxo (Bill Dailey) 7. Re: GPS Jammer (Jim Lux) 8. Re: Google's Spanner uses GPS and atomic time (paul swed) -- Message: 1 Date: Tue, 02 Oct 2012 19:30:20 -0700 From: Jim Lux jim...@earthlink.net To: time-nuts@febo.com Subject: Re: [time-nuts] GPS Modulation and 10 MHz Delay Lock Message-ID: 506ba33c.1010...@earthlink.net Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 10/2/12 3:39 PM, johncr...@aol.com wrote: Hello All - Here is a link that describes the GPS modulation. You do not need the 1 pps to lock the 10 MHz oscillator to the atomic clock in the satellites. http://www.kowoma.de/en/gps/signals.htm If you look at the block diagram you see PN code modulates the carrier at the 1.023 MHz chip rate. This is done by BPSK modulation of the carrier with the PN code. It can be done simply with a double balanced mixer. This spreads the signal with PSK at the chip( i.e. code clock) rate. Note also the modulo - 2 addition of the data to the code sequence. This called code inversion modulation. After de-spread of the code in the receiver - the signal is then simple BPSK and may be demodulated by a Costas or Squaring Loop to get at the data message. The obtain precision frequency needed I believe the T bolt simply locks to the chipping rate using some form of Delay Lock Loop. It is NOT at PLL. There is no need what ever to deal with the 1 pps using this method. The internal 10 MHz oscillator is controlled by this locking circuit and is part of the code correlation loop. That's not quite how it works.. It would work for terrestrial links where there is no Doppler, but in the GPS case, there is significant Doppler shift on all the signals. Since the carrier and the chips are generated from a common source on the spacecraft (the carrier frequency is a multiple of the chip rate, in fact), you can recover carrier and chips at the same time. But.. most receivers these days don't actually have an analog tracking loop at all. They digitize the input signal (1 bit quantizer) at a rate that makes the carrier alias down to something convenient (a few hundred kHz is typical.. you want it far enough away from zero that Doppler never makes it go negative). In the experimental receiver in SCaN Testbed flying on ISS it's about 39 MHz sample rate.
[time-nuts] Tbolt Orignal Cost
Hello all - I Wonder what price the T-Bolts sold for new in single quantities. Maybe more than $465? I ran across this some time ago - Perhaps someone has a better number but the later ones seem to go for $ 1500 for the kit with the antenna from a distributor. Note that this is a later model than the one offered surplus. Google Trimble Thunder bolt cost and found among other things... Trimble Embedded Components - TOPP Group, Inc - Data Solutions www.toppcompanies.com/tds/tds-component-models.htm Trimble GPS Developer Kits - Inquire about available volume discounts. TTPart no, Mfr.Part no. Description, PDF, Price List ... 35349-00, Thunderbolt Starter Kit: inlcudes Thunderbolt, bullet antenna, 75 foot cable, power connector, $1,595.00 ... I think this is a 12 channel receiver. I suspect that years ago the 8 channel was about the same. 73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Antenna Restrictions
Chris - your solution worked for me - until the grass covered my old PU truck. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB PM Receiver
Hello All - I am new to this forum but have read it for a couple of years. The present fulminations on the WWVB format change should be reconsidered in the light of prior art. As an old RfFengineer I do not see any issue with the format and the business about patents is not really applicable as these modulations have been in use since the 1920's. For one thing the tube analog color TVs managed to have a PLL recover the color sub-carrier using less than 10 cycles of the 3.5 mHz color burst stuck on top of the horizontal sync pulse. Here we have a continuous signal with occasional phase reversals and some amplitude steps. This is a much simpler problem that is not begging for sophisticated solutions, however much tun they may be to implement. The following or variations should work. 1. Receive with a decent antenna but keep the bandwidth such that it does not store the phase information. 2. Use preselection with care because the filter is going to have to flywheel down and then back up as the phase reverses. This will reduce the carrier level during that interval. More bandwidth will shorten the time of the ring down-ring up period. The filter must be phase stable with temperature. 3. AGC with gain may be desired for weak signals. If so implement with one of the Analog Devices handy dandy VGAs. They provide 50 or more dB of voltage controlled gain with absolutely NO phase variation as the gain is changed. 4. Now get rid of the short term amplitude variation - for this you need a limiter with no AM to PM conversion. Again Analog Devices has suitable parts with phase variation of less than 5 degrees for more than 70 db dynamic range. The AM is now gone. These parts also output a log of the analog input - so the AM keying could be recovered using that if desired for some complex sampling scheme. 5. OK - now you have an amplitude stable BPSK modulated carrier. 6. Get rid of the BPSK. Double the frequency - then divide by 2 and the carrier is recovered less the PSK. For the doubler you may wish to consider a Quadrature Driven Mixer Frequency Doubler - has no Hi Q circuits and the output is easily filtered. See my article in QEX last year March April. Or the classic Class C or diode doubler can be used as long as they preserve the input phase. 6a. A Costas Lopp is another classic method that should work fine. 7. Narrow the bandwidth (say 10 Hz) with a PLL to clean up the output of the doubler. This will get rid of wide band noise and improve the SNR. Again the PLL must preserve phase - so some temperature test may be a good idea. The PLL also provides a constant level clock to the Divide by 2 to avoid phase jitter. 8. Divide by 2 - and you have a clean 60 kHz signal with no modulation. This can the be used for frequency comparison by the phase method or to lock up a good local standard. So it should be possible to implement a receiver without infringing any patents and without reams of signal processing code. Hopefully this is helpful.-73 John C.Roos K6IQL Spring Hill Kansas ___ 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] WWVB Receiver
To Paul re my receiver thoughts. You are absolutely correct in some regards and for some implementations. The limiter must have very high dynamic range and must not convert changes in input level to changes in transmission phase; i.e. No AM to PM conversions. Thus my specific suggestion of the Analog Devices parts. Normal diode limiters and such simple stuff won't work.The internal configuration of Low AM-PM limiters is 9 or 10 stage of emitter coupled differential pairs. Now conveniently available as ICs. Likewise you need a slow PLL in front of the divide by 2 in order to coast through fast fades. Alternatively you can use the log output of the limiter as an instantaneous level indication and not sample the input during periods of no signal. Some implementations could use a really stable frequency standard as the VCXO in the PLL and freeze the control voltage during fades. I did this once with good success. Using the HP 10544 we could ride through a 2 hour outage and maintain code synchronization. So it is possible. With regard to filter phase, I mentioned BW because it is easier to measure. Wider BW = better phase response for all else being equal. However properly implemented - the suggested configuration should work OK. Once upon a time -1976 - A similar setup was used to extract the carrier for a BPSK demodulator from a spread spectrum IF signal. Good luck with your design. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] BPSK Receiver GPS Antenna siting
Various comments - Hal mentioned SNR for the scheme I suggested. A PLL can be a coherent demodulator of arbitrary bandwidth. Thus the PLL at the output of the doubler can have a small bandwidth since at that point there is no PSK, it having been removed by the doubler. So given a stable VCXO you can probably get down to 1 Hz and thereby achieve a good SNR. There is a lot of stuff out there on phase tracking receivers that do exactly that. You know the frequency so the loop does not have to search far and the BW can be increased for acquisition and closed up for tracking. On writing reams of code - my point was that it is not required to used the admittedly more powerful software techniques to do this job - I noted that one reason to write reams of code is for the fun of it, this is after all a hobby. GPS Antenna Siting - Lets not make this so hard. Mine is at 6 ft elevation and is blocked to an elevation angle of 20 to 30 degrees by a house within 15 ft and a forest of trees. I have room and no restrictions but I also have severe thunderstorms - so the house plays lightning protect for the antenna. My T bolt tracks a Rb to better than 1e-12 over 24 hours with no serious 10 MHz phase bumps as plotted on a strip chart recorder. So - Put your antenna at 6 ft in back yard. Start out on a photo tripod - who is gonna notice? set up a t bolt at EL=5 AMU=0 Damping = 1.2 and Time Constant = 100 sec. get the t bolt manual get Tbolt monitor get Lady Heather and read all that stuff. Run Lady Heather antenna survey (command SAS) for at least two days - you get a map of signal level in dBc vs elevation Reset the Tbolt elevation mask to reject anything that is shown as blocked using the signal level map. Likewise experiment with the AMU setting to reject the weak = poor signals. Mine works good with AMU all the way up to 10 as fewer good satellites are better than lots of weak ones. The satellites are in high orbits so masking those below 25 degrees is OK and the AMU sets the acceptable signal level - at AMU 10 my setup throws out those below about 40 dBc - the strong guys go up to 50. This is a function of you antenna performance so some experimentation is required. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] WWVB Receiver Comments
For David - re WWVB carrier recovery. On squaring vs absolute values for carrier recovery. Never heard of using absolute value. As I said in my initial remarks - some perusal of the prior art is helpful for this problem. There are 70 years of literature on how to do this for any imaginable purpose. The squaring loop that I described and the Costas loop are classical solutions. Both can be made to work for this problem, though I prefer the former having implemented it previously. Same applies to narrow band tracking of weak signals. It is in the literature. This is not hard stuff nor is getting a GPS signal without the neighbors finding out and repeating the riot scene from Young Frankenstein. -73 john k6iql ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
