Re: [time-nuts] Using digital broadcast TV for timing?
Maybe cell site transmissions are better? Raj The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why a 10MHz sinewave output?
Hal Murray wrote: li...@rtty.us said: Thank goodness for that inertia. I can still cable up a 100Kcps sine wave standard to run stuff from long ago. When I run into a box that uses a T1 signal for a clock reference - not so easy in the basement. How much gear is there that uses T1 for a clock input? Is there any interest in a board/chip/whatever that converts 10 MHz to T1? A clean design using a decimal DDS should fit into a small FPGA, maybe a CPLD. There is quite a bit of telecom gear that will take a T1(or E1) as a clock reference. A T1 BITS will provide an all 1's AMI signal which looks like 772 kHz on a scope. ___ 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] Why a 10MHz sinewave output?
We already have one of those that everybody can use. It's called the earth. Craig McCartney 160 Montalvo Road Palomar Park, CA 94062 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Tuesday, February 07, 2012 12:41 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Why a 10MHz sinewave output? On 02/07/2012 09:02 AM, David J Taylor wrote: For the real analog fans, how about a 1 Hz sinewave output and watch for the zero-crossings! G Precise? No! 11 uHz sine anyone, 24 hours period? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Why a 10MHz sinewave output?
It's slated for destruction around December 21 of this year... We already have one of those that everybody can use. It's called the earth. ___ 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] Using digital broadcast TV for timing?
Hi Back in the late 90's Symmetricom made up some disciplined Rubidium's that ran off of cell towers. If you Google Timesource 2700 you can probably find a lot of information on them. Until people figured out what was in them, they were a great way to score a PRS-10 Rubidium (great phase noise) for very little money ($200 or so). The telcom companies used them for a while and ultimately scrapped a lot of them out. Rumor is that not all cell towers are as locked up time wise as they should be. The discipline obviously only works if they are. Even if you have a good tower today, there is no guarantee that it's locked tomorrow. GPS can drop out due to equipment issues and you will drift as the tower drifts. Bottom line, it's a solution that brings in a whole new set of problems. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Wednesday, February 08, 2012 6:01 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Using digital broadcast TV for timing? Maybe cell site transmissions are better? At least one company makes them. http://tinyurl.com/72j5e6n http://www.endruntechnologies.com/telecom-primary-reference-source.htm It's CDMA. I don't know much about cell phones, but I think that's the old protocol that will probably/eventually fade away. I don't know anybody who has worked with them. The advantage is that you can set them up in your machine room and don't need an outside antenna. (If your cell phone works there, this should work too.) I'd expect the time accuracy would be not as good as GPS. It would be off by the time-of-flight from the cell tower, 5 microseconds per mile. That's 5 microseconds per mile which is no problems unless you are a time-nut. (I don't know if the cell towers add more to that.) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why a 10MHz sinewave output?
Hi Some (but by no means all) gear actually looks at some of the data fields on the T1 before it will accept it as a reference. In most cases a bits clock does fine. Of course you do need a proper balanced line driver and all that stuff to get it running. Still not something that's readily available in my basement. At work - not a problem. The simple / stupid way to do it is to use a framer chip. They are cheap these days and they have all the driver stuff built in. They will even pack the data fields with hey, I'm a good clock - use me. Run a cheap PLL to generate the framer clock and you are up and running. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J.D. Schoedel Sent: Wednesday, February 08, 2012 1:52 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Why a 10MHz sinewave output? Hal Murray wrote: li...@rtty.us said: Thank goodness for that inertia. I can still cable up a 100Kcps sine wave standard to run stuff from long ago. When I run into a box that uses a T1 signal for a clock reference - not so easy in the basement. How much gear is there that uses T1 for a clock input? Is there any interest in a board/chip/whatever that converts 10 MHz to T1? A clean design using a decimal DDS should fit into a small FPGA, maybe a CPLD. There is quite a bit of telecom gear that will take a T1(or E1) as a clock reference. A T1 BITS will provide an all 1's AMI signal which looks like 772 kHz on a scope. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using digital broadcast TV for timing?
Hi These days the easiest solution might be to put an Ethernet device a few floors up (where you can see the sky) and haul packets on down to the bottom of the canyon. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Tuesday, February 07, 2012 9:01 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Using digital broadcast TV for timing? GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time code in the signal and I'm pretty sure the bits are clocked at a very accurate rate. Also TV receivers are very easy to find and put hooks into. I'd bet the broadcast TV signal could be almost as good as GPS. The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why a 10MHz sinewave output?
Hey, you're not supposed to actually read those planning applications for hyperspace bypasses! D. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: 08 February 2012 16:54 To: time-nuts@febo.com Subject: [time-nuts] Why a 10MHz sinewave output? It's slated for destruction around December 21 of this year... We already have one of those that everybody can use. It's called the earth. ___ 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] Why a 10MHz sinewave output?
David C. Partridge- Hey, you're not supposed to actually read those planning applications for hyperspace bypasses! I suppose then it may be my fault.. ;-) -Arthur ___ 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] The System: U.S. DoD, DoT Tell FCC No LightSquared
Ashton Carter, U.S. deputy secretary for Defense, and John Porcari, deputy secretary for Transportation, have written an official letter to the assistant secretary of Commerce stating that “there appear to be no practical solutions or mitigations that would permit the LightSquared broadband service.” Carter and Porcari are co-chairs of the National Executive Committee for Space-Based Positioning, Navigation, and Timing. This represents the strongest intra-government statement to date on the issue. Their letter further states that “both LightSquared’s original and modified plans for its proposed mobile network would cause harmul interference to many GPS receivers. Additionally, an analysis by the Federal Aviation Administration has concluded that the LightSquared proposals are not compatible with several GPS-dependent aircraft safety-of-flight systems.” “No additional testing is warranted at this time,” the authors conclude. They further propose to “draft new GPS spectrum interference standards that will help inform future proposals for non-space, commercial uses in the bands adjacent to the GPS signals.” No response has emerged from either the Federal Communications Commission or the National Telecommunications and Information Administration, the two bodies charged with making a determination on the issue. But the letter appears to signal a coming end to a conflict that has occupied many, and tied up many resources and consumed many millions of dollars, for the past year. One source commented off the record that “Our hope is this will be the end of the matter, and the FCC will withdrawal its initial approval and inform LSQ they must seek the 500 MHz in a different portion of the spectrum.” ___ 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] PTS synthesizers
I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. 73 Bill wa4lav ___ 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] PTS synthesizers
Hi Bill Welcome aboard, and good to see you again:-) Other than the breakdown at the rear of the catalog, and the various references against individual items, I've never seen another list as such, so If you do have other option numbers it might be easier if you could indicate what they are in case anyone is familiar with them. I still haven't had time yet to try your remote interface, which I suspect others here might also find very interesting, but I have completed the scans of my X10 and PTS250 manuals and will be making those available as soon as I've finished processing the images. Regards Nigel GM8PZR In a message dated 08/02/2012 22:11:29 GMT Standard Time, wlfuq...@uky.edu writes: I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. ___ 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] PTS synthesizers
Start off by downloading their catalog http://www.programmedtest.com/images/pdf/ptscatalog.pdf Jump to pages 28, 29 and 30 If you are LUCKY the synth you have or are looking at can be decoded. For me I'd say 2 out of 3 have characters that are not in the above or, X-nn options that 'never existed' has been the reply from emailing PTS's support. -pete On Wed, Feb 8, 2012 at 2:10 PM, Bill Fuqua wlfuq...@uky.edu wrote: I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. 73 Bill wa4lav ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTS synthesizers
I want to take advantage of the topic just to ask if anybody has any manual or schematics of the PTS 040. I realize that the PTS 160 is close enough, taking in account the different frequency range, and they use almost the same modules but it would be nice to have the right manual. What is about the remote interface? Please, share the info. Best regards, Ignacio, EB4APL On 08/02/2012 23:57, gandal...@aol.com wrote: Hi Bill Welcome aboard, and good to see you again:-) Other than the breakdown at the rear of the catalog, and the various references against individual items, I've never seen another list as such, so If you do have other option numbers it might be easier if you could indicate what they are in case anyone is familiar with them. I still haven't had time yet to try your remote interface, which I suspect others here might also find very interesting, but I have completed the scans of my X10 and PTS250 manuals and will be making those available as soon as I've finished processing the images. Regards Nigel GM8PZR In a message dated 08/02/2012 22:11:29 GMT Standard Time, wlfuq...@uky.edu writes: I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTS synthesizers
On 2/8/12 3:23 PM, EB4APL wrote: I want to take advantage of the topic just to ask if anybody has any manual or schematics of the PTS 040. I realize that the PTS 160 is close enough, taking in account the different frequency range, and they use almost the same modules but it would be nice to have the right manual. What is about the remote interface? Please, share the info. Way back in the 80s, I used a PTS and the remote interface, so I'm going off memory. As I recall, it's basically a BCD parallel thing with a strobe. The general architecture of their synthesizers is a series of decade modules, so the parallel interface just extends that to as many digits as you have modules. Settling time to the new frequency is pretty fast (1 microsecond, I think) but not necessarily phase continuous, and, there can be glitches during the transition (i.e. if one module switches faster than the others). no fancy-shmancy DDSes back in those days. ___ 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] Using digital broadcast TV for timing?
A bit off topic, but historically related back in the 70's, I tapped off the color burst oscillator in my TV (a Heathkit) to get a 3.579545 MHz (315/88 MHz) source to calibrate my homebrew frequency counter. The TV's color burst oscillator was phase locked to the color burst signal on the broadcast signal (which was on the back porch of the hori sync signals). Supposedly, the networks were locked to Cesium standards traceable to NBS for LIVE broadcasts, such as news and sports. Taped programs, of course, were not usable as an accurate source. In any case, that signal served my purposes at the time (providing a reference for calibrating my counter that was more accurate than anything else available to me). I'm not sure if, what, or where analog TV is still broadcast, but I think there are still a few stations (low power) around. You might still be able to use that signal, IF you can dig it out of your old analog TV. ;-) I do have analog tv's hooked up to my cable box - I suspect that live broadcasts would still have an accurate color burst, so maybe I think the other methods discussed here (ie, GPS) would provide easier and more reliable timing sources. ;-) Trying to locate the appropriate signal(s) in a digital TV today would be interesting. Just as a historical aside. Jerry Finn Santa Maria, CA Date: Tue, 7 Feb 2012 18:01:26 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? Message-ID: cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time code in the signal and I'm pretty sure the bits are clocked at a very accurate rate. Also TV receivers are very easy to find and put hooks into. I'd bet the broadcast TV signal could be almost as good as GPS. The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE-5680A's suitability for use as a 10 MHz reference for microwave transverters
Hi Here is a little more on how much of a problem you have. If you would like the spurs to be down 70 dbc at 10 GHz. They go up by 20 log N. in this case N is 1000. That gets you 60 db. Spurs at 10 MHz would have to be down at -130 dbc to make it at 10 GHz. If you want noise over 10 KHz to be 60 db down, it goes by 10 log BW. That gets you to 1 Hz noise at -100. The same 60 db to 10 MHz then applies. You would need -160 dbc phase noise at 10 MHz to hit that. Both of those would be hard to hit with any Rb. Fortunately you can use a multi step multiplication chain. Once you make that decision, noise and spurs on the Rb are not a big issue. Bob On Feb 7, 2012, at 1:52 PM, John Ackermann N8UR j...@febo.com wrote: I am just finishing my promised stability and phase noise measurements on a batch of inexpensive Rb standards; I hope to publish the results tomorrow evening. In the meantime, I've looked at two of the FE-5680s and their phase noise is significantly worse than either the Efratom FRS or the Datum LPRO -- in particular, there is a forest of spurs all the way from 1 Hz on out, most of them at around -80dBc or worse. By the time you multiply that to 10 GHz, that's only about 20 dB below the carrier! Apart from the spurs, the noise floor is significantly higher than the other two types. A clean-up oscillator would be an interesting add-on. John On 2/7/2012 12:48 PM, C. Turner wrote: Hello, As has been mentioned here before, the output of the non-tunable FE-5680A's has been noted to have low-level spurs in it - no doubt due to the way the various frequency loops are derived within, some using DDS techniques. It is for this reason that when I packaged my FE-5680A in its own, stand-alone enclosure I included a fairly narrow band (+/-6 kHz @ -6dBc) crystal-based bandpass filter in the output. After more recent testing of two FE-5680A's using two different 10 GHz microwave transverters, I've determined that this filtering just isn't enough. At first, it was assumed/hoped that the racket that I was hearing was coming from somewhere else - perhaps the switching up-converter or some other interaction - or just something odd about my homebrew 10 GHz transverter, but this is, unfortunately, not the case. In testing with a DownEast Microwave 10 GHz transverter fitted with an N5AC synthesizer, the CW notes sounded nice and clean when locked to the Z3801 and there was only a trace of modulation that I'd not really noticed before when I used the Efratom LPRO-101, but when the '5680A was connected, the incidental PM was bad enough that it was difficult to determine where, exactly, zero beat was! Since the synthesizer uses a fairly high reference frequency internally there was little impediment to the low-level phase modulation on the reference. I compared this with my own homebrew 10 GHz transverter. This unit uses an 18.4 MHz Butler VCXO that is multiplied to 110.4 MHz which is then fed to a brick oscillator with the 110.4 MHz being compared to the 10 MHz reference using a harmonic mixer, locking to the 400 kHz residual. Since this unit has a comparatively low loop bandwidth in the VCXO the grunge was considerably reduced, but still objectionable, giving some hope that a simple VCXO scheme might make the '5680A usable. I still have yet to do a more-detailed analysis of the phase modulation that is appearing on the 10 GHz signals, but I can clearly hear a low frequency modulation source (perhaps the lock-in amplifier) plus a myriad of other audio frequency components and their harmonics. Again, with the LPRO-101 was very clean by comparison and I could *just* hear some similar, very low-level noises in the background that I'd not really noticed before. As it is, the '5680A-based reference is unusable with the N5AC synthesizer and its wide loop bandwidth and almost usable with my homebrew transverter and its comparatively narrow loop bandwidth. I'm now bent on making the '5680A usable as a microwave reference, but my current plans are to build a simple 10 MHz Butler VCXO and then lock it to the '5680A using a very slow loop filter: In that way, I'm hoping that the phase noise will be largely that of the 10 MHz VCXO and its cheap CPU-type crystal rather than the '5680A! Clint KA7OEI ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTS synthesizers
Jim, I already have the info on the remote interface, taken from the PTS 160 doc and other sources, I was asking if he was talking about some specific gadget. I also was using at those years some remotely controlled PTS's , did you know the JPL MK IV receiver exciter? I think it was also a 040 but I'm not sure, because these changed the phase smoothly but I think that there is an option with a DDS to allow such thing. Unfortunatelly those exciters are now dismantled and I think the doc was dumped, anyway I'll have to make a phone call. Ignacio On 09/02/2012 1:17, Jim Lux wrote: On 2/8/12 3:23 PM, EB4APL wrote: I want to take advantage of the topic just to ask if anybody has any manual or schematics of the PTS 040. I realize that the PTS 160 is close enough, taking in account the different frequency range, and they use almost the same modules but it would be nice to have the right manual. What is about the remote interface? Please, share the info. Way back in the 80s, I used a PTS and the remote interface, so I'm going off memory. As I recall, it's basically a BCD parallel thing with a strobe. The general architecture of their synthesizers is a series of decade modules, so the parallel interface just extends that to as many digits as you have modules. Settling time to the new frequency is pretty fast (1 microsecond, I think) but not necessarily phase continuous, and, there can be glitches during the transition (i.e. if one module switches faster than the others). no fancy-shmancy DDSes back in those days. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTS synthesizers
Jim Lux said the following on 02/08/2012 07:17 PM: On 2/8/12 3:23 PM, EB4APL wrote: I want to take advantage of the topic just to ask if anybody has any manual or schematics of the PTS 040. I realize that the PTS 160 is close enough, taking in account the different frequency range, and they use almost the same modules but it would be nice to have the right manual. What is about the remote interface? Please, share the info. Way back in the 80s, I used a PTS and the remote interface, so I'm going off memory. As I recall, it's basically a BCD parallel thing with a strobe. The general architecture of their synthesizers is a series of decade modules, so the parallel interface just extends that to as many digits as you have modules. Settling time to the new frequency is pretty fast (1 microsecond, I think) but not necessarily phase continuous, and, there can be glitches during the transition (i.e. if one module switches faster than the others). no fancy-shmancy DDSes back in those days. The remote interface is very simple to talk to; in fact, I've wired up a mating connector with just a bunch of jumpers right in the connector for a single frequency. It is BCD with a couple of twists -- the programming info is on some web pages (including one of mine, but I think I still have an error that needs to be fixed in my description). There's a guy who will put front panel controls on a remote-interface PTS, with thumbwheel switches, level control, and BCD connector, along with nice looking labels, for a very reasonable price. Contact me off-list if you'd like his contact info; I'm not sure that he wants it widely published as it's a spare-time business. I've had him modify several units for me, and been very happy with the results. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why a 10MHz sinewave output?
On 02/08/2012 06:15 PM, Bob Camp wrote: Hi Some (but by no means all) gear actually looks at some of the data fields on the T1 before it will accept it as a reference. In most cases a bits clock does fine. Of course you do need a proper balanced line driver and all that stuff to get it running. Still not something that's readily available in my basement. At work - not a problem. The simple / stupid way to do it is to use a framer chip. They are cheap these days and they have all the driver stuff built in. They will even pack the data fields with hey, I'm a good clock - use me. Run a cheap PLL to generate the framer clock and you are up and running. The T1/DS1 signal as well as the E1 signal has a way to indicate to which standard level the delivered clock is traceable to. If you are in luck, you get a PRS (ANSI top reference) or PRC (ETSI/ITU top reference) indication, which would mean that you have a G.811 compatible clock within 1E-11 in frequency. In their infinite wisdom the 1544 kHz and 2048 kHz standards slightly out of tune with each other as they stem from different advances in the respective PDH hierarchy development, which later rippled into the SONET and SDH counter-parts. Their SSM codes for Quality Level encoding has now rippled over to Synchronous Ethernet, which is nothing but a very strange SDH interface rate. The ITU-T G.781 standard is a place to get lost to understand these messages, so is ANSI T1.101. Digging around the ITU-T G.810-813 and G.823-825 specs is recommended. There is also several good ETSI specs and a good TR to read up on. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why a 10MHz sinewave output?
On 2/8/12 4:51 PM, Magnus Danielson wrote: On 02/08/2012 03:25 PM, Craig S McCartney wrote: We already have one of those that everybody can use. It's called the earth. Yes, but you don't have it hanging in a neat position in your office, living room or lab, now do you? Besides, if you are a time-nut your rock will be more time-accurate than the real thing. :) I haven't special ordered a backup earth for my lab, or at least I won't admit to it, as you all know that I have at least three operational and a few stand-bys to put into operation in case I need to service one of them. And now you know why we keep sending those spacecraft with high performance radios to Mars. Because, you know, with all those earthquakes and tsunamis, the Earth rotation keeps changing. And that enormously massive moon also interacts with the rotation too, not to mention our thick atmosphere. Mars, tiny moons, almost no atmosphere, no oceans, seismically quiet... I'll pitch it as a new slogan: Mars clocks, when Earth rotation just isn't stable enough. ___ 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] PTS synthesizers
On 2/8/12 4:47 PM, EB4APL wrote: Jim, I already have the info on the remote interface, taken from the PTS 160 doc and other sources, I was asking if he was talking about some specific gadget. I also was using at those years some remotely controlled PTS's , did you know the JPL MK IV receiver exciter? I think it was also a 040 but I'm not sure, because these changed the phase smoothly but I think that there is an option with a DDS to allow such thing. Unfortunatelly those exciters are now dismantled and I think the doc was dumped, anyway I'll have to make a phone call. Could be. We have tons and tons of 3325Bs and 3325As floating around, though. I haven't seen any PTS recently, however, a quick check of the asset database shows a fair number of them owned by Rabi Wang and William Diener. The latter has most of them.. Models PTS040SANIX-7, PTS250 and X10SAN10 for the most part. Both of those guys are in the Frequency and Timing Advanced Instrument Development Group. A couple years ago, we cleaned out some storage closets FULL of those gold plated brick shaped modules that made up the Mark III (at least that's what I was told). ___ 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] science projects
While delayed, I would think that the signal freqs would still need to be maintained... hmmm, maybe not... interesting science project... anyone? anyone? ;-) Jerry I'm waiting to see a good time-nuts project at the science fair. (at any level up to ISEF) There's a lot of good ones out there (perhaps not on the scale of tvb's experimental demonstration of gravitational effects on atomic clocks) that would lend themselves to execution by everyone from 6th to 12th grade. Clearly, since people do spend their entire professional life doing this and write dissertations on it, it can be up to ISEF or Siemens Talent Search standards. Maybe we could come up with a suggested list and start shopping it around. Jim ___ 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] science projects
The number one TN science fair project would have to be measuring the speed of light using some simple, inexpensive method such as reflecting sunlight from rotating mirrors On Wed, Feb 8, 2012 at 5:44 PM, Jim Lux jim...@earthlink.net wrote: While delayed, I would think that the signal freqs would still need to be maintained... hmmm, maybe not... interesting science project... anyone? anyone? ;-) Jerry I'm waiting to see a good time-nuts project at the science fair. (at any level up to ISEF) There's a lot of good ones out there (perhaps not on the scale of tvb's experimental demonstration of gravitational effects on atomic clocks) that would lend themselves to execution by everyone from 6th to 12th grade. Clearly, since people do spend their entire professional life doing this and write dissertations on it, it can be up to ISEF or Siemens Talent Search standards. Maybe we could come up with a suggested list and start shopping it around. Jim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTS synthesizers
You are right, the golden bricks were from the Mark III, we were supposed to wear white cotton gloves to handle them. This was a wonderful receiver, the one who put the man in the Moon and tracked Pioneer X from Jupiter and beyond. I heard that Viterbi himself was in the design team, probably leading the PLL stuff. Good old days, even we were younger. Regards, Ignacio On 09/02/2012 2:39, Jim Lux wrote: On 2/8/12 4:47 PM, EB4APL wrote: Jim, I already have the info on the remote interface, taken from the PTS 160 doc and other sources, I was asking if he was talking about some specific gadget. I also was using at those years some remotely controlled PTS's , did you know the JPL MK IV receiver exciter? I think it was also a 040 but I'm not sure, because these changed the phase smoothly but I think that there is an option with a DDS to allow such thing. Unfortunatelly those exciters are now dismantled and I think the doc was dumped, anyway I'll have to make a phone call. Could be. We have tons and tons of 3325Bs and 3325As floating around, though. I haven't seen any PTS recently, however, a quick check of the asset database shows a fair number of them owned by Rabi Wang and William Diener. The latter has most of them.. Models PTS040SANIX-7, PTS250 and X10SAN10 for the most part. Both of those guys are in the Frequency and Timing Advanced Instrument Development Group. A couple years ago, we cleaned out some storage closets FULL of those gold plated brick shaped modules that made up the Mark III (at least that's what I was told). ___ 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] Norman Ramsey
Just a month ago I found out that Norman Ramsey had died. I met and talked with him about 20 some odd years ago before he recieved the Nobel Prize for Physics. He talked about the first Magentron that he ever saw which was a secret weapon brought to the US to be tested and worked with to make high resolution radar. He was at MIT at the time. He was an interesting fellow to talk to. One of our faculty at the University of Kentucky was one of his graduate students when he was working on the atomic frequency standard. When he received the check, many years after he developed the atomic clock he gave about half to his graduate students that had worked with him. He worked out a deal to purchase a number of computers, and each of these guys got one. The one Dr. McAdam got was an ATT 16 bit system. Fairly fancy at the time. I have a couple of Rubidium sources and think about my short discussion with him at the time. His graduate student was a ham but Dr. Ramsey never was. Dr. McAdam did a great deal of research in atomic physics at UofK before he retired a couple of years ago. 73 Bill wa4lav ___ 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] PTS synthesizers
I don't remember which owns which, but some PTS models are under the Wavetek brand. I have a Wavetek 5135A, which looks and acts just like the PTS 160. I also have a PTS D310 that I plan to fix up with two sets of wheel switches to be built into the front panel, but don't recall if I already found the parallel interface data - especially the pinout. Is that readily available? Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Norman Ramsey
Three of the GREAT MEN of atomic physics have died pretty recently, R.V. Pound, Ed Purcell, and Norman Ramsey. They were call at Harvard. -John = Just a month ago I found out that Norman Ramsey had died. I met and talked with him about 20 some odd years ago before he recieved the Nobel Prize for Physics. He talked about the first Magentron that he ever saw which was a secret weapon brought to the US to be tested and worked with to make high resolution radar. He was at MIT at the time. He was an interesting fellow to talk to. One of our faculty at the University of Kentucky was one of his graduate students when he was working on the atomic frequency standard. When he received the check, many years after he developed the atomic clock he gave about half to his graduate students that had worked with him. He worked out a deal to purchase a number of computers, and each of these guys got one. The one Dr. McAdam got was an ATT 16 bit system. Fairly fancy at the time. I have a couple of Rubidium sources and think about my short discussion with him at the time. His graduate student was a ham but Dr. Ramsey never was. Dr. McAdam did a great deal of research in atomic physics at UofK before he retired a couple of years ago. 73 Bill wa4lav ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using digital broadcast TV for timing?
A thought and an observation related to getting timing from broadcast DTV signals. BC DTV uses a scheme called 8VSB, which includes a pilot 'carrier' at the low frequency end of the signal. This is used to help the receiver lock to the TX so that the phase information can be accurately decoded. It seems to me that this might be a possible source of a useful frequency reference, although there is no guarantee that it is traceable to anything or even very accurate. The observation is that one of my local stations simulcasts the same programming in both 1080 and 780 formats, and when I switch from the 1080 channel to the 780, there is a very obvious 1 to 2 second delay in both the audio and video of the 780 format. These are being transmitted as separate streams on the same carrier. Definitely suggests that there is a lot of 'processing' and buffering going on while putting the complete bit stream together. Tom Holmes, N8ZM Tipp City, OH EM79 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of jerryfi Sent: Wednesday, February 08, 2012 7:38 PM To: time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? A bit off topic, but historically related back in the 70's, I tapped off the color burst oscillator in my TV (a Heathkit) to get a 3.579545 MHz (315/88 MHz) source to calibrate my homebrew frequency counter. The TV's color burst oscillator was phase locked to the color burst signal on the broadcast signal (which was on the back porch of the hori sync signals). Supposedly, the networks were locked to Cesium standards traceable to NBS for LIVE broadcasts, such as news and sports. Taped programs, of course, were not usable as an accurate source. In any case, that signal served my purposes at the time (providing a reference for calibrating my counter that was more accurate than anything else available to me). I'm not sure if, what, or where analog TV is still broadcast, but I think there are still a few stations (low power) around. You might still be able to use that signal, IF you can dig it out of your old analog TV. ;-) I do have analog tv's hooked up to my cable box - I suspect that live broadcasts would still have an accurate color burst, so maybe I think the other methods discussed here (ie, GPS) would provide easier and more reliable timing sources. ;-) Trying to locate the appropriate signal(s) in a digital TV today would be interesting. Just as a historical aside. Jerry Finn Santa Maria, CA Date: Tue, 7 Feb 2012 18:01:26 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? Message-ID: cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gm ail.com Content-Type: text/plain; charset=ISO-8859-1 GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time code in the signal and I'm pretty sure the bits are clocked at a very accurate rate. Also TV receivers are very easy to find and put hooks into. I'd bet the broadcast TV signal could be almost as good as GPS. The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Low-Cost Rubidium Performance
As threatened, I've measured stability (out to a trustworthy 10K seconds) and phase noise of the three popular telecom surplus Rb standards. I looked at two units of the FE-5680, two units of the Efratom FRS, and one Datum LPRO. (I have two more LPROs but don't have the mating connector on hand, and didn't want to solder on all three.) The Cliff Notes version: * The units had similar short term stability from 1 to 100 seconds. * Above 100 seconds, the LPRO was the clear winner. The FE and FRS split, with one of each being the worst two. * The FE-5680 phase noise loses big-time, both in noise floor and in the quantity and amplitude of spurs. That DDS comes with a price. * The LPRO has the best phase noise floor and cleanest spectrum. Pretty plots and the underlying data are at http://febo.com/pages/oscillators/rubes/ Important note: there's known to be a lot of variability among these units, so my sample size of one or two each isn't a guarantee that your unit will perform similarly. Next step is to do some longer-term stability measurements (out to 100K seconds). You may see that data in a month or so. John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using digital broadcast TV for timing?
All gone these days in the US. Indeed I can speak to the CBS network it was driven by CS references in the 80s and 90s. I used CBS for aligning my references Xtal oven oscillators that were never ever turned off in a large facility that uplinked all 8 CBS regions and 22 other cable networks. Unfortunately few could get to that color burst signal as devices called frame synchronizers came into play from the 80s to the 90s. They would strip off that burst and insert the local reference of generally much lower quality. As far as todays digital TV signals they can contain significant jitter. But its actually trickier then that and I honestly have to say I am not sure that you might not be able to get something useful. Several interesting points. Many of the television transmitters do use GPS referenced sources. Its an interesting exploration. I simply don't have the time though. Regards Paul WB8TSL On Wed, Feb 8, 2012 at 7:38 PM, jerryfi jerryfi...@yahoo.com wrote: A bit off topic, but historically related back in the 70's, I tapped off the color burst oscillator in my TV (a Heathkit) to get a 3.579545 MHz (315/88 MHz) source to calibrate my homebrew frequency counter. The TV's color burst oscillator was phase locked to the color burst signal on the broadcast signal (which was on the back porch of the hori sync signals). Supposedly, the networks were locked to Cesium standards traceable to NBS for LIVE broadcasts, such as news and sports. Taped programs, of course, were not usable as an accurate source. In any case, that signal served my purposes at the time (providing a reference for calibrating my counter that was more accurate than anything else available to me). I'm not sure if, what, or where analog TV is still broadcast, but I think there are still a few stations (low power) around. You might still be able to use that signal, IF you can dig it out of your old analog TV. ;-) I do have analog tv's hooked up to my cable box - I suspect that live broadcasts would still have an accurate color burst, so maybe I think the other methods discussed here (ie, GPS) would provide easier and more reliable timing sources. ;-) Trying to locate the appropriate signal(s) in a digital TV today would be interesting. Just as a historical aside. Jerry Finn Santa Maria, CA Date: Tue, 7 Feb 2012 18:01:26 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? Message-ID: cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time code in the signal and I'm pretty sure the bits are clocked at a very accurate rate. Also TV receivers are very easy to find and put hooks into. I'd bet the broadcast TV signal could be almost as good as GPS. The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] science projects
Hi guys My 2 cents...from first person experience ;-) (although this doesn't have much to do with frequency standard-related science fair projects...) I am actually a high school junior in one of Dallas/Ft Worth, Texas's, suburbs, and I have been competing in ISEF science fairs for the last 3 years. From my experience, the engineering judges look for projects that are novel and can justify why this new method is better than mainstream methods. Besides that, it is almost like a marketing fair since the presentation style also plays a huge role. In my opinion, high school ISEF science fair these days is not about hey look at what I made, but its more like how can it be done better and why should it replace mainstream technology. My project last year was essentially building a general purpose compact X-band radar system capable of distance and speed measurements. My major application was its use as no-physical-contact biomedical instruments. I got 2nd place at regionals and didnt advance any farther than state. In retrospect, I believe my weaknesses back then were because radars are nothing new; I just presented a new application and I feel like I could've presented my project better towards the judges. I believe the live demo of a part of the radar, showing how professionally made it was (custom PCBs, etc), and the detailed documentation binder were a huge plus to my project. This year, I'm working on making a monolithic CMOS THz imaging array with built-in signal processing integrated circuit. (Just in case you're wondering, my I'm employeed at the TxACE center at UTD as a intern). My job is to basically design on the transistor level and integrate the signal processing circuit into the CMOS THz imaging array. At the end, I plan to use this project and compete in STS, Siemens, and ISEF. Unlike my last year's project, monolithic THz imaging arrays with on-chip signal processing is something relatively new. Why is a teenager (me) doing on this list? Because I have a passion for electronics, especially analog and RF ever since when I was very young. I love what I'm doing and I dont plan on stopping. Ok I'll stop rambling now...sorry for the long email guys... Ray Xu KF5LJO On Wed, Feb 8, 2012 at 8:03 PM, Chris Albertson albertson.ch...@gmail.comwrote: The number one TN science fair project would have to be measuring the speed of light using some simple, inexpensive method such as reflecting sunlight from rotating mirrors On Wed, Feb 8, 2012 at 5:44 PM, Jim Lux jim...@earthlink.net wrote: While delayed, I would think that the signal freqs would still need to be maintained... hmmm, maybe not... interesting science project... anyone? anyone? ;-) Jerry I'm waiting to see a good time-nuts project at the science fair. (at any level up to ISEF) There's a lot of good ones out there (perhaps not on the scale of tvb's experimental demonstration of gravitational effects on atomic clocks) that would lend themselves to execution by everyone from 6th to 12th grade. Clearly, since people do spend their entire professional life doing this and write dissertations on it, it can be up to ISEF or Siemens Talent Search standards. Maybe we could come up with a suggested list and start shopping it around. Jim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- __ 73, Ray Xu KF5LJO ___ 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] Using digital broadcast TV for timing?
Thanks Paul. You and Bob Camp provided some good updates/info. It may present enough of a challenge/reward for someone to examine further. I'm with you on the available time front - too many other projects/commitments to pursue further myself. I'll be interested if Chris, or someone else, can make some headway though. Jerry AG6HH From: paul swed paulsw...@gmail.com To: jerryfi jerryfi...@yahoo.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, February 8, 2012 7:07 PM Subject: Re: [time-nuts] Using digital broadcast TV for timing? All gone these days in the US. Indeed I can speak to the CBS network it was driven by CS references in the 80s and 90s. I used CBS for aligning my references Xtal oven oscillators that were never ever turned off in a large facility that uplinked all 8 CBS regions and 22 other cable networks. Unfortunately few could get to that color burst signal as devices called frame synchronizers came into play from the 80s to the 90s. They would strip off that burst and insert the local reference of generally much lower quality. As far as todays digital TV signals they can contain significant jitter. But its actually trickier then that and I honestly have to say I am not sure that you might not be able to get something useful. Several interesting points. Many of the television transmitters do use GPS referenced sources. Its an interesting exploration. I simply don't have the time though. Regards Paul WB8TSL On Wed, Feb 8, 2012 at 7:38 PM, jerryfi jerryfi...@yahoo.com wrote: A bit off topic, but historically related back in the 70's, I tapped off the color burst oscillator in my TV (a Heathkit) to get a 3.579545 MHz (315/88 MHz) source to calibrate my homebrew frequency counter. The TV's color burst oscillator was phase locked to the color burst signal on the broadcast signal (which was on the back porch of the hori sync signals). Supposedly, the networks were locked to Cesium standards traceable to NBS for LIVE broadcasts, such as news and sports. Taped programs, of course, were not usable as an accurate source. In any case, that signal served my purposes at the time (providing a reference for calibrating my counter that was more accurate than anything else available to me). I'm not sure if, what, or where analog TV is still broadcast, but I think there are still a few stations (low power) around. You might still be able to use that signal, IF you can dig it out of your old analog TV. ;-) I do have analog tv's hooked up to my cable box - I suspect that live broadcasts would still have an accurate color burst, so maybe I think the other methods discussed here (ie, GPS) would provide easier and more reliable timing sources. ;-) Trying to locate the appropriate signal(s) in a digital TV today would be interesting. Just as a historical aside. Jerry Finn Santa Maria, CA Date: Tue, 7 Feb 2012 18:01:26 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? Message-ID: cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time code in the signal and I'm pretty sure the bits are clocked at a very accurate rate. Also TV receivers are very easy to find and put hooks into. I'd bet the broadcast TV signal could be almost as good as GPS. The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] science projects
On 2/8/12 6:03 PM, Chris Albertson wrote: The number one TN science fair project would have to be measuring the speed of light using some simple, inexpensive method such as reflecting sunlight from rotating mirrors Actually, that's probably not a good project: it's been done, in almost exactly that way. The key to a winning project is doing something that nobody's done before. It doesn't mean it has to be Nobel unique, but just different. For instance, if you came up with an unusual way to measure speed of light (other than all the classic spinning mirror, toothed wheel, interferometer schemes) Or, if you were to measure the Allen Deviation of a bunch of pendulums of different types. This would be a good junior division (grade 6,7,8: age 11-13) project because it would allow you to do some statistics (very unusual in junior division, beyond the usual misapplication of Excel Data Analysis tools), and if you could come up with some theory about why the ADEV would vary with material or length (e.g. smaller effect of air drag or something), you could test it. In senior division, to be a top project, it would have to be something like we discuss on this list. tvb's Cs clock verification of Einstein might work, but you'd have to be pretty good at showing why it's not just a rehash of someone else's traveling clock demo. Something with coupled oscillator behavior in an interesting context would be interesting. (measuring the small coupling between mechanical oscillators on a concrete floor as a function of distance or orientation) Building your own atomic standard from scratch would be impressive, but would be unlikely to be a top winner at state or ISEF level (they tend not to reward design and build engineering projects, even in the engineering categories, unless you've got some novel design feature you're trying.) Characterizing some sort of oscillators could be a winner, especially if it's a kind of oscillator with usefulness that hasn't been well characterized before. On Wed, Feb 8, 2012 at 5:44 PM, Jim Luxjim...@earthlink.net wrote: While delayed, I would think that the signal freqs would still need to be maintained... hmmm, maybe not... interesting science project... anyone? anyone? ;-) Jerry I'm waiting to see a good time-nuts project at the science fair. (at any level up to ISEF) ___ 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] PTS synthesizers
I had a web page up with PTS info that I had gathered, corrected (some), and consolidated for multiple devices in one doc. I got an email from PTS requesting I remove the documents. I now have a place holder page recommending people look for HP test equipment rather than PTS. PTS doesn't share HP's (now Agilent) openness about sharing documents. -Rex, KK6MK On 2/8/2012 2:57 PM, gandal...@aol.com wrote: I still haven't had time yet to try your remote interface, which I suspect others here might also find very interesting, but I have completed the scans of my X10 and PTS250 manuals and will be making those available as soon as I've finished processing the images. Regards Nigel GM8PZR In a message dated 08/02/2012 22:11:29 GMT Standard Time, wlfuq...@uky.edu writes: I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why a 10MHz sinewave output?
I thought the same thing but I think Mark was referring to the end date of the Mayan calender. Now those guys were Time-Nuts!! Ed On 2/8/2012 12:09 PM, David C. Partridge wrote: Hey, you're not supposed to actually read those planning applications for hyperspace bypasses! D. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: 08 February 2012 16:54 To: time-nuts@febo.com Subject: [time-nuts] Why a 10MHz sinewave output? It's slated for destruction around December 21 of this year... We already have one of those that everybody can use. It's called the earth. ___ 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] Morion MV89 output level?
Got my replacement FE-5680 and a MV89 in from Nichegeek. I figured I'd better power up and check the MV89 before I let 'em know everything was ok. The MV89 is warming up nicely, the current is down to 290 mA (and still dropping), but the output seems low; about 40 mV RMS as measured on a scope with a 10Meg 10x probe. (Datasheet spec is +7 +/- 2 dBm.) The output is too weak to reliably trigger my 5345A counter. The reference voltage measures 4.90 VDC. If anyone can make a quick measurement on their MV89, I'd appreciate it. thanks! newell N5TNL ___ 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] science projects
On 2/8/12 7:37 PM, Ray Xu wrote: Hi guys My 2 cents...from first person experience ;-) (although this doesn't have much to do with frequency standard-related science fair projects...) I am actually a high school junior in one of Dallas/Ft Worth, Texas's, suburbs, and I have been competing in ISEF science fairs for the last 3 years. From my experience, the engineering judges look for projects that are novel and can justify why this new method is better than mainstream methods. You bet. I *am* an ISEF engineering judge, and you are exactly right. You need to know your field well enough to be able to explain why what you are doing is different, and why there's at least a chance of it being better. Besides that, it is almost like a marketing fair since the presentation style also plays a huge role. In my opinion, high school ISEF science fair these days is not about hey look at what I made, but its more like how can it be done better and why should it replace mainstream technology. At the top levels, it has never been look what I made (the perjorative term is baking soda volcano). I don't know that presentation style is super important, at least at ISEF: there are entries from all around the world, from places with all manner of cultural styles and technical display proficiency. Most notably, a lot of the entrants aren't speaking English and are using a translator of variable quality (i.e. they may be able to translate Urdu and English, but odds are, they aren't an engineer) What the judges look for is - good explanation of what you did and why you did it - getting back to the idea of picking a good topic that's novel (where time-nuts can help, eh? research on background doesn't have to all be literature searches.. asking experts is good) - responding to questions as asked - We all get trained (or have experience and share notes) on stopping the elevator pitch - being able to answer obscure details about what you did (to root out the third assistant bottle washer in professor so-and-so's lab and the kit builder) - it being YOUR project (again, working as a team member in a university lab isn't going to be a winner for the fair.. good in real life, not good for competition) My project last year was essentially building a general purpose compact X-band radar system capable of distance and speed measurements. My major application was its use as no-physical-contact biomedical instruments. I got 2nd place at regionals and didnt advance any farther than state. In retrospect, I believe my weaknesses back then were because radars are nothing new; I just presented a new application and I feel like I could've presented my project better towards the judges. Yes.. you basically built a measurement instrument that already existed. If that had been incidental to your application, and you focused on the novelty of the application (e.g. detecting sleep apnea or something like that) it might have done better. Or, if your radar was somehow novel in design (e.g. you didn't use a gunnplexer or DRO based door opening radar as the base, and it wasn't a simple FMCW homodyne) I believe the live demo of a part of the radar, showing how professionally made it was (custom PCBs, etc), and the detailed documentation binder were a huge plus to my project. Yes and no. live demo is always good (because it shows YOU did it), and face it, it's SHOWTIME detailed documentation is good (shows good work practice, and if the judge picks a page at random and asks about it, and you can answer. I've judged software projects and done this, and the person had ZERO clue about what the module I was doing did and why it was there.) Professionally made, maybe, maybe not. Depends on the context and what resources you had available to you. I saw an amazing project last year that was literally built from scrap electronics the guys had scrounged at the junkyard in their third world country. I've never seen so many different kinds of connectors and ancient phenolic PC boards repurposed in my life. But the darn thing worked and did what they wanted. They got good marks on ingenuity and use of resources. (Their project topic wasn't all that great, unfortunately..) If you are living in Silicon Valley, and you show up with homemade PC boards or deadbug style construction, and you explained why that was the choice you made, rather than sending it out to any of a zillion fab houses around your house, that would be fine. There's an awful lot of really disappointed entrants who have access to a top-notch lab, have gorgeous printouts and graphs, but did something mundane and repetitious. This is really common in the biomed/molecular bio area, because it's sexy, and it's not too hard to get hooked up with someone with good lab facilities, but the field is moving so fast that you run the risk of doing what labs pay a technician $15/hr to do. The student gets so caught up
[time-nuts] earth as a clock
On 2/8/12 8:11 PM, Ed Palmer wrote: I thought the same thing but I think Mark was referring to the end date of the Mayan calender. Now those guys were Time-Nuts!! But oddly, as Feynman pointed out, they only used Venus, and not Mars (or Jupiter, although the synodic period is pretty long for Jupiter).. Mars is pretty prominent in the morning sky these days, as it always is when a spacecraft is about a third of the way there, which is why I was reminded of it. ___ 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] Using digital broadcast TV for timing?
On Wed, Feb 8, 2012 at 7:48 PM, jerryfi jerryfi...@yahoo.com wrote: Thanks Paul. You and Bob Camp provided some good updates/info. It may present enough of a challenge/reward for someone to examine further. I'm with you on the available time front - too many other projects/commitments to pursue further myself. I'll be interested if Chris, or someone else, can make some headway though. OK if not DTV what other common signal that you could pick up without use of exotic equipment (so this entirely eliminates rotating neutron starts or pulsars) what else can you get that has decent timing other then GPS and CDMA. I'm not giving up on DTV yet. The video signal is compressed so it may be basically white noise but I bet it is wrapped in some transport like packets that are regular. In practice GPS works well but a question came up here What could you use if GPS went away?I said I bet there is some signal all around us that just happens to have precision timing embedded in it. Maybe DTV maybe it's direct broadcast TV. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using digital broadcast TV for timing?
Other than LightSquared, an event that made GPS go away would most likely eliminate most interest in ultra accuracy time keeping. On 02/08/2012 09:13 PM, Chris Albertson wrote: On Wed, Feb 8, 2012 at 7:48 PM, jerryfijerryfi...@yahoo.com wrote: Thanks Paul. You and Bob Camp provided some good updates/info. It may present enough of a challenge/reward for someone to examine further. I'm with you on the available time front - too many other projects/commitments to pursue further myself. I'll be interested if Chris, or someone else, can make some headway though. OK if not DTV what other common signal that you could pick up without use of exotic equipment (so this entirely eliminates rotating neutron starts or pulsars) what else can you get that has decent timing other then GPS and CDMA. I'm not giving up on DTV yet. The video signal is compressed so it may be basically white noise but I bet it is wrapped in some transport like packets that are regular. In practice GPS works well but a question came up here What could you use if GPS went away?I said I bet there is some signal all around us that just happens to have precision timing embedded in it. Maybe DTV maybe it's direct broadcast TV. -- 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] science projects
On Wed, 8 Feb 2012 21:37:36 -0600 Ray Xu rayxu...@gmail.com wrote: I am actually a high school junior in one of Dallas/Ft Worth, Texas's, suburbs, and I have been competing in ISEF science fairs for the last 3 years. [...] This year, I'm working on making a monolithic CMOS THz imaging array with built-in signal processing integrated circuit. (Just in case you're wondering, my I'm employeed at the TxACE center at UTD as a intern). My job is to basically design on the transistor level and integrate the signal processing circuit into the CMOS THz imaging array. At the end, I plan to use this project and compete in STS, Siemens, and ISEF. Unlike my last year's project, monolithic THz imaging arrays with on-chip signal processing is something relatively new. Wow... I'm... astonished... Back about 15 years ago, a friend an i build a calculator based on an embedded version of the 80186... and we were the big shots at our high school... Now studendts build THz imaging arrays? I guess, in 10 or 20 years, students will be building warp drives... ^^' Well.. back to topic... I'd very much like to see the documentation of your projects. Why? Because i'd like to learn from others and and your projects seem very interesting :-) Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] PTS synthesizers
I have a 250 no manual and would REALLY like a copy of the scan. If it cannot be posted somewhere, could I get a copy mailed to me? Thanks very much! Don Rex I had a web page up with PTS info that I had gathered, corrected (some), and consolidated for multiple devices in one doc. I got an email from PTS requesting I remove the documents. I now have a place holder page recommending people look for HP test equipment rather than PTS. PTS doesn't share HP's (now Agilent) openness about sharing documents. -Rex, KK6MK On 2/8/2012 2:57 PM, gandal...@aol.com wrote: I still haven't had time yet to try your remote interface, which I suspect others here might also find very interesting, but I have completed the scans of my X10 and PTS250 manuals and will be making those available as soon as I've finished processing the images. Regards Nigel GM8PZR In a message dated 08/02/2012 22:11:29 GMT Standard Time, wlfuq...@uky.edu writes: I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. ___ 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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTS synthesizers
I forgot to add that I traced out the switch socket on the rear of my 250 unit; each decade socket has four color coded lines that are 4-line BCD and the corresponding switch is needed. I've forgotten if the common from the switches goes to ground or to plus. I think that if a IEEE488 bus connector is present that the decades will also be BCD based. Don Rex I had a web page up with PTS info that I had gathered, corrected (some), and consolidated for multiple devices in one doc. I got an email from PTS requesting I remove the documents. I now have a place holder page recommending people look for HP test equipment rather than PTS. PTS doesn't share HP's (now Agilent) openness about sharing documents. -Rex, KK6MK On 2/8/2012 2:57 PM, gandal...@aol.com wrote: I still haven't had time yet to try your remote interface, which I suspect others here might also find very interesting, but I have completed the scans of my X10 and PTS250 manuals and will be making those available as soon as I've finished processing the images. Regards Nigel GM8PZR In a message dated 08/02/2012 22:11:29 GMT Standard Time, wlfuq...@uky.edu writes: I am new to the list and would like to know if anyone has a list of the suffixes (options) for PTS synthesizers. There seem to be a number of them that are not in their catalog. ___ 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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Morion MV89 output level?
-- Message: 2 Date: Wed, 08 Feb 2012 22:15:41 -0600 From: Scott Newell newell+timen...@n5tnl.com To: time-nuts@febo.com Subject: [time-nuts] Morion MV89 output level? Message-ID: mailman.980.1328767168.1783.time-n...@febo.com Content-Type: text/plain; charset=us-ascii; format=flowed Got my replacement FE-5680 and a MV89 in from Nichegeek. I figured I'd better power up and check the MV89 before I let 'em know everything was ok. The MV89 is warming up nicely, the current is down to 290 mA (and still dropping), but the output seems low; about 40 mV RMS as measured on a scope with a 10Meg 10x probe. (Datasheet spec is +7 +/- 2 dBm.) The output is too weak to reliably trigger my 5345A counter. The reference voltage measures 4.90 VDC. If anyone can make a quick measurement on their MV89, I'd appreciate it. thanks! newell N5TNL -- It seems that many of these oscillators have an internal problem with a output coupling capacitor. Yours does in fact have this problem. You will need to open the package up and replace a chip capacitor to get ti to work right. This capacitor is right next to the RF output pin. I told the seller about the problem and this is their reply: _ Hi Tom, Thanks for letting us know about that. As you may know, this is an secondhand item and some unwelding problem may happen to capacitor inside.But it can be good with general application. If you need it for high precision, then you have to check the circuit and fix it by yourself. 1. Many units (about 50%) would have about 20dB output less than 7dBm. It is said that the inside coupling capacitance would separate from body while outputting, which leads to being invalid. 2. Some units become normal when the temperature is stable, but they would fluctuate during the process heating from cold to stable. Actually, it is the same problem as the above situation. The units can be observed the output waves when it comes to stability. 3. Tuning frequency has parasitic amplitude modulation effect, and 5MHz output can be seen in normal MV89 Output spectrum. _ I just did two of them. Once this is fixed, the units work very nice. Regards, Tom ___ 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] Using digital broadcast TV for timing?
I'm not completely convinced that DTV has been eliminated as a source, but it would take some study (and discussions with the DTV providers). There may be something there. The problem you have is that so many (most, if not all) stable rf signal sources are derived from GPS today, so that in the EXTREMELY unlikely event that all (24+) GPS sats went off the air, many of those sources would all be affected to one degree or another. You might look at the Russian Glonass system, the European Gallileo system (which is only in prototyping stage), and possibly the Chinese Beidou NAVSATS. Gallileo and Glonass work similar to GPS, but Beidou is a different beast. There are receivers that use both GPS and GLONASS, but I don't have any direct experience with them. WWV (and related HF time signal sources) are an obvious alternative source. NIST operates WWV transmitters at 2.5, 5, 10, 15 and 20 MHz from Fort Collins, CO, and WWVH from Hawaii. These signals are locked to Cs standards. There are other HF time signals from Canada, etc, you might check out. Depending on what you want to do, you might just consider synchronizing a Rb, or a bank of Rb's to GPS. Then if GPS went away, the Rb's would free run for a considerable time. Considerable needs to be defined by your timing requirements, and duration, in the non-GPS environment. And then, of course, there are Cesium standards available, if you have deep pockets. Jerry Finn AG6HH From: Chris Albertson albertson.ch...@gmail.com To: jerryfi jerryfi...@yahoo.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, February 8, 2012 9:13 PM Subject: Re: [time-nuts] Using digital broadcast TV for timing? On Wed, Feb 8, 2012 at 7:48 PM, jerryfi jerryfi...@yahoo.com wrote: Thanks Paul. You and Bob Camp provided some good updates/info. It may present enough of a challenge/reward for someone to examine further. I'm with you on the available time front - too many other projects/commitments to pursue further myself. I'll be interested if Chris, or someone else, can make some headway though. OK if not DTV what other common signal that you could pick up without use of exotic equipment (so this entirely eliminates rotating neutron starts or pulsars) what else can you get that has decent timing other then GPS and CDMA. I'm not giving up on DTV yet. The video signal is compressed so it may be basically white noise but I bet it is wrapped in some transport like packets that are regular. In practice GPS works well but a question came up here What could you use if GPS went away? I said I bet there is some signal all around us that just happens to have precision timing embedded in it. Maybe DTV maybe it's direct broadcast TV. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Morion MV89 output level?
Hi Nevell, FYI my one delivers almost +5dBm on 50 Ohm.Ref Voltage +4,86 Volt. Rgds Ernie. -Original Message- From: Scott Newell newell+timen...@n5tnl.com To: time-nuts time-nuts@febo.com Sent: Thu, Feb 9, 2012 5:16 am Subject: [time-nuts] Morion MV89 output level? Got my replacement FE-5680 and a MV89 in from Nichegeek. I figured 'd better power up and check the MV89 before I let 'em know verything was ok. The MV89 is warming up nicely, the current is own to 290 mA (and still dropping), but the output seems low; about 0 mV RMS as measured on a scope with a 10Meg 10x probe. (Datasheet pec is +7 +/- 2 dBm.) The output is too weak to reliably trigger my 345A counter. The reference voltage measures 4.90 VDC. If anyone can make a quick measurement on their MV89, I'd appreciate it. hanks! ewell N5TNL __ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using digital broadcast TV for timing?
Other than LightSquared, an event that made GPS go away would most likely eliminate most interest in ultra accuracy time keeping. But this is time nuts. I think it's interesting to consider where we might get a second source of time or frequency frequency. How good is it? What does it cost? How much can amateurs do? Maybe something will work where GPS doesn't. I was going to try GPS in a big machine room but we didn't get that far. It didn't work in the adjoining office complex. I assume there was too much metal in the building. but EMI from all the local PCs probably didn't help much. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE-5680A's suitability for use as a 10 MHz reference for microwave transverters
El 09/02/2012 01:40, Bob Camp escribió: Hi Here is a little more on how much of a problem you have. If you would like the spurs to be down 70 dbc at 10 GHz. They go up by 20 log N. in this case N is 1000. That gets you 60 db. Spurs at 10 MHz would have to be down at -130 dbc to make it at 10 GHz. As a side note (since I've just asked by), does the phase noise also go up by 20 log N when multiplying? Regards, Javier ___ 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] Morion MV89 output level?
I just powered up one of my MV89A's and measured ~7 dBm into my HP 8920B, but as Tom has mentioned some MV89A's develop a dry joint around the output bypass capacitor http://www.hellocq.net/forum/showthread.php?t=283551 What is the date and revision number on yours? I have 2 here 07/34 and 07/31 both Rev 3 bought from fluke.l Sam Got my replacement FE-5680 and a MV89 in from Nichegeek. I figured I'd better power up and check the MV89 before I let 'em know everything was ok. The MV89 is warming up nicely, the current is down to 290 mA (and still dropping), but the output seems low; about 40 mV RMS as measured on a scope with a 10Meg 10x probe. (Datasheet spec is +7 +/- 2 dBm.) The output is too weak to reliably trigger my 5345A counter. The reference voltage measures 4.90 VDC. If anyone can make a quick measurement on their MV89, I'd appreciate it. thanks! newell N5TNL ___ 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.
