Re: [time-nuts] webcam app to watch for and time stamp changes
Well, considering that actively driving a LCD segment involves passing an AC field over it, in electrostatic drive, you could detect the existence of AC or not on a segment, but you would have to mask out that of other segments. On the other hand, you can expect a multiplexed drive. An E-field detector as such would be able to pick up the shifts. Wonders if the multiplexing is done by the same clock or a free-running clock. If it is the same clock, just picking up the E-field from the multiplex suffice to detect the clock ticking. Magnus, That is indeed a clever idea. I'm sure the AC drive is derived from the same clock so if Jim can see the LCD segment/backplane waveform he's got a handle on the clock. When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Do you have suggestions on what sort of antenna to use to pick up the LCD AC E-field? I'd expect the LCD drive current to be vanishing small. /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.
Re: [time-nuts] webcam app to watch for and time stamp changes
Content-Type: text/plain; charset=ISO-8859-1 In message 657D7F7CC03849419A2A90752E6A60A6@pc52, Tom Van Baak writes: When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Looking for TimePod 5330A for purchase or rental
Hello all, I'd like to purchase or rent a milesdesign TimePod 5330A Programmable Cross Spectrum Analyzer. Rental would be for a duration of a few to several months (can be agreed on), in this year. Careful treatment of the device will be assured. My application is the measurement of phase noise of ultrapure microwave signals generated by a femtosecond laser. This state-of-the-art approach produces ultra-low noise microwaves. The goal specifications are -70 dBc/Hz at 0.1 Hz and -90 dBc/Hz at 1 Hz, -110 dBc/Hz at a frequency of 9 GHz. The Symmetricom version of the TimePod does not have the capability of measurement at 0.1 Hz offset frequency, therefore I am looking for the original device. Any suggestions are welcome. Stephan Schiller Universität Düsseldorf (Germany) www.exphy.uni-duesseldorf.de ___ 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] webcam app to watch for and time stamp changes
On 03/03/2013 10:00 AM, Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In message657D7F7CC03849419A2A90752E6A60A6@pc52, Tom Van Baak writes: When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Darn. I should have guessed. 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] Looking for TimePod 5330A for purchase or rental
Stephan, On 03/03/2013 10:57 AM, Stephan Schiller wrote: Hello all, I'd like to purchase or rent a milesdesign TimePod 5330A Programmable Cross Spectrum Analyzer. Rental would be for a duration of a few to several months (can be agreed on), in this year. Careful treatment of the device will be assured. My application is the measurement of phase noise of ultrapure microwave signals generated by a femtosecond laser. This state-of-the-art approach produces ultra-low noise microwaves. The goal specifications are -70 dBc/Hz at 0.1 Hz and -90 dBc/Hz at 1 Hz, -110 dBc/Hz at a frequency of 9 GHz. This would require down-mixing, and the TimePod can do that, but the larger Symmetricom boxes can't handle it. with down-mixing I mean that after splitting the signal, two mixers with a pair of 8,99 GHz signal sources (to make the signal about 10 MHz) should do it. You also want a quiet reference oscillator. Got to try this one myself one day. The Symmetricom version of the TimePod does not have the capability of measurement at 0.1 Hz offset frequency, therefore I am looking for the original device. Good point. Can the Symmetricom version grab data so it can be presented by the TimeLab with that range? 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] Looking for TimePod 5330A for purchase or rental
Hi It was my impression that the Symmetricom device and the Miles device were identical in performance / capabilities. The issue with the Symmetricom device is that you unlock features on a cost per feature basis. If there are other capability limits past that, that's very bad news. Bob On Mar 3, 2013, at 4:57 AM, Stephan Schiller step.schil...@hhu.de wrote: Hello all, I'd like to purchase or rent a milesdesign TimePod 5330A Programmable Cross Spectrum Analyzer. Rental would be for a duration of a few to several months (can be agreed on), in this year. Careful treatment of the device will be assured. My application is the measurement of phase noise of ultrapure microwave signals generated by a femtosecond laser. This state-of-the-art approach produces ultra-low noise microwaves. The goal specifications are -70 dBc/Hz at 0.1 Hz and -90 dBc/Hz at 1 Hz, -110 dBc/Hz at a frequency of 9 GHz. The Symmetricom version of the TimePod does not have the capability of measurement at 0.1 Hz offset frequency, therefore I am looking for the original device. Any suggestions are welcome. Stephan Schiller Universität Düsseldorf (Germany) www.exphy.uni-duesseldorf.de ___ 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] Nortel EBSCTM-C / NTPB15AB-05
Hi The display on that unit looks nice. Seems like I'm going to have to do some probing if I want to know what's on the connector. I doubt there's a pps back there, but who knows…. Bob On Mar 3, 2013, at 12:40 AM, Arthur Dent golgarfrinc...@yahoo.com wrote: Has anybody traced out the connections on the DB-37 connector on the back of this beast yet? I never looked at the 37-pin connector on the back of the unit but back in December, 2012 I did post that I had added a display and an A.C. supply to the one I had and it seems to be working fine. I use LH to control and keep track of how it's doing but as others have mentioned, not all the set-up data you tell it to save gets saved. The link to the photo I'd previously posted is below. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.jpg ___ 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] webcam app to watch for and time stamp changes
On 3/3/13 1:00 AM, Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In message 657D7F7CC03849419A2A90752E6A60A6@pc52, Tom Van Baak writes: When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Yes, but perhaps there's enough leakage to make this work. After all, the EMI requirement (assuming it's running at 32 kHz) isn't particularly stringent and because the fob is small, the radiated field at any distance is going to very small. OTOH, I can put a probe or coil right on or around the fob. I'll let you all know what I detect when I try it tomorrow. ___ 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] Don't use cheap cables -- a cautionary tale
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. ___ 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] webcam app to watch for and time stamp changes
On 03/03/2013 03:46 PM, Jim Lux wrote: On 3/3/13 1:00 AM, Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In message 657D7F7CC03849419A2A90752E6A60A6@pc52, Tom Van Baak writes: When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Yes, but perhaps there's enough leakage to make this work. After all, the EMI requirement (assuming it's running at 32 kHz) isn't particularly stringent and because the fob is small, the radiated field at any distance is going to very small. OTOH, I can put a probe or coil right on or around the fob. I'll let you all know what I detect when I try it tomorrow. An electrostatic shield will not contain the H-field from the shifting currents. 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] Don't use cheap cables -- a cautionary tale
Yup, they are BNC (by necessity). I'm still experimenting but it may be an ill-fitting connector on the cheap patch cable. Switching to a better quality cable seems to have solved the problem, one way or the other. John Bob Camp said the following on 03/03/2013 10:10 AM: 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. ___ 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] Don't use cheap cables -- a cautionary tale
On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. Kevin ___ 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] Don't use cheap cables -- a cautionary tale
Hi BNC's suffer from shield separation issues and from basic wear out on the connector it's self. Cheap coax = shield seperation. On the connector its self it's either plating or loss of spring in the fingers. The best solution is to cut the connector off the cable. That way at least it doesn't mess you up a second time. Once you get a big enough pile of single ended cables, it's time to get out the crimp tool…. Bob On Mar 3, 2013, at 10:46 AM, John Ackermann j...@febo.com wrote: Yup, they are BNC (by necessity). I'm still experimenting but it may be an ill-fitting connector on the cheap patch cable. Switching to a better quality cable seems to have solved the problem, one way or the other. John Bob Camp said the following on 03/03/2013 10:10 AM: 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. ___ 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] Don't use cheap cables -- a cautionary tale
On 3/3/13 8:00 AM, Kevin Rosenberg wrote: On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. ___ 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] webcam app to watch for and time stamp changes
On Sat, 02 Mar 2013 11:33:02 -0800, Jim Lux wrote: I am interested in the timing behavior of my RSA fob, which changes every 60 seconds. Since I'm not about to open it up and probe inside, I was wondering if someone had a clever way, say using a USB web cam, to log the changes over a 48 hour period. You'd point the web cam at the fob, and it would log the time when the display changes Or one might even be able to look at the blinking 1 pps indicator using a light and photocell or something.. Isn't this Just what the doctor ordered http://smallhacks.wordpress.com/2012/11/11/reading-codes-from-rsa- secureid-token/ CFO ___ 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] webcam app to watch for and time stamp changes
When LCD wristwatches became common in the seventies we, in the frequency and timing group of a space tracking facility, investigated the possibility of adjusting our new watches against our standard. We found that a a small copper plate, about 1 X 2 cm, resting against the display and connected to a scope probe was able to pick up enough 32 KHz energy to be displayed in the scope. Then connected the vertical output to an HP 5245L counter referenced to our standard and set the gate time to 10 seconds and got the frequency. We learned that the watch had to be worn in order to operate at the right temperature, the body acting as an oven, so you has to wear it backside in order to access the trimmer (yes, at that time those watches had and adjusting trimmer, maybe heritage from the mechanical ones, laser trimming arrived later). Our group became very popular and busy adjusting every watch our colleagues bought to a few seconds per month. Ignacio, EB4APL On 03/03/2013 16:29, Magnus Danielson wrote: On 03/03/2013 03:46 PM, Jim Lux wrote: On 3/3/13 1:00 AM, Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In message 657D7F7CC03849419A2A90752E6A60A6@pc52, Tom Van Baak writes: When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Yes, but perhaps there's enough leakage to make this work. After all, the EMI requirement (assuming it's running at 32 kHz) isn't particularly stringent and because the fob is small, the radiated field at any distance is going to very small. OTOH, I can put a probe or coil right on or around the fob. I'll let you all know what I detect when I try it tomorrow. An electrostatic shield will not contain the H-field from the shifting currents. 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] webcam app to watch for and time stamp changes
On 3/3/13 9:12 AM, EB4APL wrote: When LCD wristwatches became common in the seventies we, in the frequency and timing group of a space tracking facility, investigated the possibility of adjusting our new watches against our standard. We found that a a small copper plate, about 1 X 2 cm, resting against the display and connected to a scope probe was able to pick up enough 32 KHz energy to be displayed in the scope. Then connected the vertical output to an HP 5245L counter referenced to our standard and set the gate time to 10 seconds and got the frequency. We learned that the watch had to be worn in order to operate at the right temperature, the body acting as an oven, so you has to wear it backside in order to access the trimmer (yes, at that time those watches had and adjusting trimmer, maybe heritage from the mechanical ones, laser trimming arrived later). Our group became very popular and busy adjusting every watch our colleagues bought to a few seconds per month. yes.. adjusting your watch to a Hydrogen Maser.. there's a time-nut-y activity... ___ 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] webcam app to watch for and time stamp changes
On Sun, Mar 3, 2013 at 12:10 AM, Tom Van Baak t...@leapsecond.com wrote: Do you have suggestions on what sort of antenna to use to pick up the LCD AC E-field? I'd expect the LCD drive current to be vanishing small. Many turns of fine magnet wire going all the way around the device. 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] webcam app to watch for and time stamp changes
On 3/3/13 8:52 AM, cfo wrote: On Sat, 02 Mar 2013 11:33:02 -0800, Jim Lux wrote: I am interested in the timing behavior of my RSA fob, which changes every 60 seconds. Since I'm not about to open it up and probe inside, I was wondering if someone had a clever way, say using a USB web cam, to log the changes over a 48 hour period. You'd point the web cam at the fob, and it would log the time when the display changes Or one might even be able to look at the blinking 1 pps indicator using a light and photocell or something.. Isn't this Just what the doctor ordered http://smallhacks.wordpress.com/2012/11/11/reading-codes-from-rsa- secureid-token/ Yes, basically.. Of course, installing your token permanently (as shown in the article) kind of defeats the purpose, since the idea of two factor authentication is something you know (the PIN/password) and something you *have* (the token). If you don't keep physical possession of the token, that's a big problem. In fact, the article is all about getting around having the human there.. the PIN is entered by his software and his software reads the token. So anyone who has access to his computer has access to his identity. And I'll bet his computer is connected to the internet, so that means *everyone* has access to whatever is secured by his token. (after all he is doing it so he can get access to his work VPN). Probably a good reason not to use NetArt Group s.r.o. in the Czech republic (his employer) if you care about security. I suppose, though, there are places that are more casual. After all, there's that guy who outsourced his work to China and mailed the guy in China his token. ___ 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] webcam app to watch for and time stamp changes
On 03/03/2013 06:18 PM, Chris Albertson wrote: On Sun, Mar 3, 2013 at 12:10 AM, Tom Van Baakt...@leapsecond.com wrote: Do you have suggestions on what sort of antenna to use to pick up the LCD AC E-field? I'd expect the LCD drive current to be vanishing small. Many turns of fine magnet wire going all the way around the device. As a E-field antenna that's not that good, as you need to see both polarities. Tossing a wire around like that would sense a little too much of both, so it will cancel out. A typical E-field antenna is a coax cable, stripped of wire, possibly with a ball attached to increase the area. H-field can make use of one or more loops before reaching the ground. The near-field H-probe is two loops, wired such that long-distanced fields cancels, but high-gradient fields is picked up. You should be able to do the same for E-field, essentially three fields, with the outer two being hooked to ground and the middle one to amp. 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] Typical HP 5370B resolution ?
Thanks all for the suggestions. I am typically measuring 5 or 10 Mhz sine waves with levels between 1 and 4 volts peak to peak into a 50 ohm load. To expand on my first email with suitable input signals I can see the 20 ps resolution of the HP5370B on a strip chart from time lab without any further effort. So far other than re seating the cards (which cured some lock up issues on a few of them) I haven't really done any maintenance to my HP5370's. I'm also using a 5 Mhz BVA as the reference oscillator for the HP5370B's in question which seems to improve things vis a vis the internal 10811's. At some point when I have some more time I'll delve into the reference oscillator matter in more detail as I'm a bit surprised at this. Magnus your suggestion to try attenuating the input signals makes a lot sense and I will try this as different signal levels do seem to make a difference. Re the other recent post re cable issues I've also encountered similar issues in the past and typically use RG400 double shielded cables. Regards Mark S Sent from my iPad ___ 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] webcam app to watch for and time stamp changes
Don't get hung up on the display EMI (for it is indeed very very tiny), look for any steady emission. Yes, the amount is small, yes it can be shielded a bit, but yes it is certainly possible to pick up. As I mentioned in my original post, you may very well need to shield out external noise to see it clearly. And with a not-so-sensitive analyzer, you'll need a pre-amp. Everything electronic emits and is detectable unless it is shielded eight ways to Sunday. Peter On 3/3/2013 7:11 AM, Magnus Danielson wrote: On 03/03/2013 10:00 AM, Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In message657D7F7CC03849419A2A90752E6A60A6@pc52, Tom Van Baak writes: When playing with watches a while ago I tried to pick up any 32 kHz signal but failed. Those with 1 Hz stepper motors were easy, but LED or LCD displays were too electro/magnetic/acoustic quiet for me to ever detect anything. Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Darn. I should have guessed. 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1430 / Virus Database: 2641/5643 - Release Date: 03/02/13 ___ 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] webcam app to watch for and time stamp changes
Content-Type: text/plain; charset=ISO-8859-1 In message 51336234.3090...@earthlink.net, Jim Lux writes: Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Yes, but perhaps there's enough leakage to make this work. Think for a moment about how little power the electronics consume in the first place, then do the math. You'll need a very (radio-)quiet place to measure in... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] webcam app to watch for and time stamp changes
On 3/3/13 10:09 AM, Poul-Henning Kamp wrote: Content-Type: text/plain; charset=ISO-8859-1 In message 51336234.3090...@earthlink.net, Jim Lux writes: Most LCD and LED clocks have a shielding metal-coating on the front glass, exactly to eliminate all EMI/EMC issues. Yes, but perhaps there's enough leakage to make this work. Think for a moment about how little power the electronics consume in the first place, then do the math. You'll need a very (radio-)quiet place to measure in... Not so oddly, I happen to have such places available, since we develop sensitive radio receivers and instruments for deep space. I don't know how well shielded from a magnetic field standpoint our usual screen rooms are (probably not very.. they're all designed for 2GHz and up), but it's easy to try. I also know someone who has a set of nested mu metal cans for this kind of thing that I might be able to borrow. We used them to calibrate little hockey puck shaped spinning magnetometer subsatellites for a sounding rocket experiment: http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/17005/1/99-0421.pdf http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/17761/1/99-1204.pdf ___ 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] Don't use cheap cables -- a cautionary tale
Hi, The use of double shielded cables does raise the question to what type of connectors to use? Regards, Henk Op 3 mrt. 2013 om 17:30 heeft Jim Lux jim...@earthlink.net het volgende geschreven: On 3/3/13 8:00 AM, Kevin Rosenberg wrote: On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. ___ 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] Don't use cheap cables -- a cautionary tale
Yes, we all have to learn that lesson... At the time I use bedea RG-223 and Belden H155 with soldered and crimped Telegaertner BNC connectors as general purpose cable (up to 2 GHz). Above that frequency I wouldn't use BNC. If you simply connect your tracking generator with the spectrum analyzer by using such a BNC cable there's not one that is absolutely stable when stressing the connector. I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's always the same. To make precise measurements I prefer screwed connectors like N or SMA. Volker Am 03.03.2013 17:30, schrieb Jim Lux: On 3/3/13 8:00 AM, Kevin Rosenberg wrote: On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. ___ 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] 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] webcam app to watch for and time stamp changes
On 3/3/13 10:47 AM, Chris Albertson wrote: It's not an e-field antenna. The goal is the sense the current in the LCD. My bet is no much of anything leaks out of that RSA device or a wrist watch either. You have to figure that tiny battery lasts for over a year and even if ALL the energy in the battery went to making RF you'd divide the battery energy by the battery life time to get power. What's have some micro watts at most. Then you figure most of the bettery power really goes into heat not RF. detecting femtowatts isn't really an issue for RF.. 1 fW is -120dBm, which is a strong signal in a lot of applications. Typical FM receivers have sensitivities around 0.2 microvolt into 50ohms, which is about a femtowatt. -150dBm is getting tougher, but is still 24 dB above the kTB noise floor in a 1 Hz BW. However, what we're looking for here is most likely a changing magnetic field. It's not being radiated away, the energy stays in the circuit (in the near field) for the most part. (question, does putting a RSA fob in a lossy magnetic medium make the battery go dead faster?) So the question really comes down to how small a repetitive change in magnetic field can be detected? Or if you're using an efield probe, it's sort of the same thing. You're not concerned about far field radiation, which will be very small (the antenna is a tiny fraction of a wavelength. Here's a similar thing.. Say you have a twisted pair carrying a signal: very little radiates away. But if you have a small probe (E or H) you can put it closer to one wire of the pair than the other, and (potentially) detect the E or H field from the wire. ___ 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] Don't use cheap cables -- a cautionary tale
I use Ponoma cables that have the strain relief. However, I don't know about the cable construction itself. ___ 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] Z3801 10 MHz reference help
All: Seeking help with my Z3801. I was referred here by some folks on the Microwave reflector. Background: It ran very well for several years. Then, when spot-checked on another counter, was found a few Hz away from 10.0MHz. Looking at GPSCon, it showed the output to not be enabled, and a status or offset word that somebody told me indicated the correction was at a maximum extreme, and suggested I looked at temperature control circuitry. I let it sit for a year or two, and have recently gotten back into it. I have read all the notes I can find on the internet, including KO4BB site. I have the user manual, but have not been able to find a service manual, including from the helpful people at HP/Agilent who will dig through their paper archives. Struck out at Symmetricom as well. Upon power up, a reow of LEDs near the power connection flash red, and then the one toward the middle of the board begins flashing green at about a 1Hz rate. Check of all power supply voltages against the diagram on the realhamradio.com web site is all good. Running GPSCon results in serial port timeouts -- no communications to/from the unit. I have verified the serial port settings. Given the vagaries of USB== serial converters these days, I have verified that the serial communications does work, using other hardware and programs, but the same laptop with which I'm trying to talk to the unit. I have read the discussion about how the temperature controller is supposed to work. It includes a discussion about the controller getting confused and breaking one lead to inject +5 volts through 10K to regain control. The fact that the voltage at TP 104 remains at 16 volts (for days) suggests that this may be what is going on. Unfortunately, to verify this problem and attempt the fix, I need clarity on the fix, and to restore the serial communications, so that I can see the status words. Any suggestions?? Thanks 73, Jim wb4...@amsat.org ___ 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] Don't use cheap cables -- a cautionary tale
Alligator clips, of course. -Bob On Sun, Mar 3, 2013 at 11:50 AM, Henk ten Pierick h...@deriesp.demon.nlwrote: Hi, The use of double shielded cables does raise the question to what type of connectors to use? Regards, Henk Op 3 mrt. 2013 om 17:30 heeft Jim Lux jim...@earthlink.net het volgende geschreven: On 3/3/13 8:00 AM, Kevin Rosenberg wrote: On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. ___ 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] Don't use cheap cables -- a cautionary tale
Some of the older synchronised signal generators (2-box systems) e.g Marconi, used TNC connectors with solid coax where signal leakage was likely to be a problem. Alan G3NYK - Original Message - From: Volker Esper ail...@t-online.de To: time-nuts@febo.com Sent: Sunday, March 03, 2013 6:49 PM Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale Yes, we all have to learn that lesson... At the time I use bedea RG-223 and Belden H155 with soldered and crimped Telegaertner BNC connectors as general purpose cable (up to 2 GHz). Above that frequency I wouldn't use BNC. If you simply connect your tracking generator with the spectrum analyzer by using such a BNC cable there's not one that is absolutely stable when stressing the connector. I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's always the same. To make precise measurements I prefer screwed connectors like N or SMA. Volker ___ 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] Don't use cheap cables -- a cautionary tale
I use some Pomonas also and I think they are single shielded except the Y which is double shielded. This may explain some artifacts I have in my house reference. Great Thread Thomas Knox To: time-nuts@febo.com From: johncr...@aol.com Date: Sun, 3 Mar 2013 14:08:15 -0500 Subject: 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 --
Re: [time-nuts] Don't use cheap cables -- a cautionary tale
I do like the strain reliefs on the Pomona cables, but the cables themselves are leaky as expected. A couple of points: 1) If you don't have any other signal sources in your environment that are close to your measurement frequency but not coherent with it, you'll probably be OK with single-shielded cables. As soon as you bring that second oscillator into the room, though, you need to start thinking about the effects of cable leakage. Most people here have more than one oscillator in the house. :) For many types of measurements single shielded cables are not a big liability. Just be aware of the compromise you're making... and don't use them when debugging a sensitive phase comparator, let's put it that way. 2) Other than physical stability, I have never seen any problems that I could blame on a BNC connector that wasn't actually defective. The shield connection issues that Bob mentions are certainly valid concerns but they can happen with any fittings, not just BNC. There's no religious reason to avoid BNCs as long as you can keep everything still. And you shouldn't be moving cables around during measurements in any event. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of li...@lazygranch.com Sent: Sunday, March 03, 2013 11:59 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale I use Ponoma cables that have the strain relief. However, I don't know about the cable construction itself. ___ 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] Don't use cheap cables -- a cautionary tale
I've previously encountered noise from mechanical movement of BNCs. You can definitely see noise bursts when you move a BNC cable around. Replacing TNC-BNC adapters and BNC-BNC cables at the analyzer with real TNC to SMA cables, and SMA to BNC adapters on the far end when necessary, solved a lot of those problems. But this was the first time I've seen a continuous beat-note type of interference that I could trace to the cabling. As a follow-on topic -- I wonder if the leakage problem would also be significant in a PPS distribution/measurement system (vs 5 or 10 MHz RF). I'd think that working with pulses and using a defined trigger level might mitigate that, but as I contemplate my rat's nest of PPS cabling I wonder if there could still be problems. John Alan Melia said the following on 03/03/2013 03:36 PM: Some of the older synchronised signal generators (2-box systems) e.g Marconi, used TNC connectors with solid coax where signal leakage was likely to be a problem. Alan G3NYK - Original Message - From: Volker Esper ail...@t-online.de To: time-nuts@febo.com Sent: Sunday, March 03, 2013 6:49 PM Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale Yes, we all have to learn that lesson... At the time I use bedea RG-223 and Belden H155 with soldered and crimped Telegaertner BNC connectors as general purpose cable (up to 2 GHz). Above that frequency I wouldn't use BNC. If you simply connect your tracking generator with the spectrum analyzer by using such a BNC cable there's not one that is absolutely stable when stressing the connector. I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's always the same. To make precise measurements I prefer screwed connectors like N or SMA. Volker ___ 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] Looking for TimePod 5330A for purchase or rental
It was my impression that the Symmetricom device and the Miles device were identical in performance / capabilities. The issue with the Symmetricom device is that you unlock features on a cost per feature basis. If there are other capability limits past that, that's very bad news. The sub-1 Hz limitation is the only real difference. The 5120A goes all the way down to 0.001 Hz, so it continues to be positioned as the best unit for PN measurements below 1 Hz. -- john, KE5FX Miles Design LLC ___ 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] Don't use cheap cables -- a cautionary tale
Fahnestock clips? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Robert Darlington Sent: Sunday, March 03, 2013 11:04 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale Alligator clips, of course. -Bob On Sun, Mar 3, 2013 at 11:50 AM, Henk ten Pierick h...@deriesp.demon.nlwrote: Hi, The use of double shielded cables does raise the question to what type of connectors to use? Regards, Henk Op 3 mrt. 2013 om 17:30 heeft Jim Lux jim...@earthlink.net het volgende geschreven: On 3/3/13 8:00 AM, Kevin Rosenberg wrote: On Mar 3, 2013, at 7:59 AM, John Ackermann j...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Don't use cheap cables -- a cautionary tale
On 3/3/13 1:41 PM, DaveH wrote: Fahnestock clips? Alligator clips, of course. But, I looked through the connector catalogs and I didn't see any double shielded Fahnestock OR Alligator clips.. More seriously, you hook both shields to the shield of the connector. Unless you want to get Triax connectors or use Tip/Ring/Sleeve 1/4 or 1/8 phone plugs. They're used for shielded twisted pair kinds of applications as well (MIL-STD-1553B, for instance) and for audio applications. ___ 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] Don't use cheap cables -- a cautionary tale
RG-223 fits with Telegaertner J01000B0608 (Solder), Buerklin 78F201 or Rosenberger 51S107-108N4 (Crimp) (straight plugs BNC) H155 fits with Telegaertner T00100B3300 N Crimp) ... Am 03.03.2013 19:50, schrieb Henk ten Pierick: Hi, The use of double shielded cables does raise the question to what type of connectors to use? Regards, Henk Op 3 mrt. 2013 om 17:30 heeft Jim Luxjim...@earthlink.net het volgende geschreven: On 3/3/13 8:00 AM, Kevin Rosenberg wrote: On Mar 3, 2013, at 7:59 AM, John Ackermannj...@febo.com wrote: Lesson learned -- use only double-shielded cable in the oscillator rack (and in any RF measurement path) from now on. I've learned that lesson as well. John Miles said that RG-58 is occasionally referred to as 'soaker hose'. RG-58 (which by the way, is a spec that officially no longer exists as part of MIL-C17-28, ditto for RG-8, RG-213, etc. The military apparently doesn't use PVC insulated wire any more.) comes in myriad forms all of which bear a passing resemblance to each other. (leaving aside the RG-58A, RG-58, RG-58C differences). The term seems to be used for any 50 ohm single shield coax that's about 0.20 inch in diameter with solid polyethylene insulation. You really need to look at the specific model number to know what the shielding looks like. It could be anything from a very loose weave of thin copper strands to something nice and dense. ___ 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] Don't use cheap cables -- a cautionary tale
After a couple of bad experiences with foamed polyethylene that got contaminated and solid polyethylene where heat had allowed the center conductor to shift, I have stuck with RG-142 and RG-400 style coax for short patch cables. For little stuff that gets soldered into place, I use add RG-316 and RG-178. Teflon makes all of these cables easy to solder without damage. On Sun, 3 Mar 2013 14:08:15 -0500 (EST), johncr...@aol.com wrote: 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 ___ 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] Don't use cheap cables -- a cautionary tale
Noise bursts come from the rubbing of the shield on the dielectric. Try putting some rg58 on the input of a guitar amp :-) Even low-noise rg58 type coax is noisy; it has some graphite on the dielectric supposedly to suppress the triboelectric (rubbing) noise. You might think Teflon would be quiet, but not so. Don John Ackermann I've previously encountered noise from mechanical movement of BNCs. You can definitely see noise bursts when you move a BNC cable around. Replacing TNC-BNC adapters and BNC-BNC cables at the analyzer with real TNC to SMA cables, and SMA to BNC adapters on the far end when necessary, solved a lot of those problems. But this was the first time I've seen a continuous beat-note type of interference that I could trace to the cabling. As a follow-on topic -- I wonder if the leakage problem would also be significant in a PPS distribution/measurement system (vs 5 or 10 MHz RF). I'd think that working with pulses and using a defined trigger level might mitigate that, but as I contemplate my rat's nest of PPS cabling I wonder if there could still be problems. John Alan Melia said the following on 03/03/2013 03:36 PM: Some of the older synchronised signal generators (2-box systems) e.g Marconi, used TNC connectors with solid coax where signal leakage was likely to be a problem. Alan G3NYK - Original Message - From: Volker Esper ail...@t-online.de To: time-nuts@febo.com Sent: Sunday, March 03, 2013 6:49 PM Subject: Re: [time-nuts] Don't use cheap cables -- a cautionary tale Yes, we all have to learn that lesson... At the time I use bedea RG-223 and Belden H155 with soldered and crimped Telegaertner BNC connectors as general purpose cable (up to 2 GHz). Above that frequency I wouldn't use BNC. If you simply connect your tracking generator with the spectrum analyzer by using such a BNC cable there's not one that is absolutely stable when stressing the connector. I tried several manufacturers, HP, Suhner, Radiall, Rosenberger, it's always the same. To make precise measurements I prefer screwed connectors like N or SMA. Volker ___ 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. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] webcam app to watch for and time stamp changes
In the watchmaker world, we have error, and personal error. The watchmaker sets the watch to get the most accurate time while sitting in his shop, and then he gives the watch to the customer with the instructions to wear the watch normally for 2 weeks, but don't reset it, and bring it back for adjustment. The watchmaker carefully checks the time, and makes note of the error from real time. He then adjusts the watch to run, at normal shop temperature, to run at -1 times the error... in other words, if the watch is 2 minutes fast over two weeks, he adjusts so that it will be 2 minutes slow over two weeks... at normal shop temperature. The customer takes his watch, and marvels at how extremely accurate it is. The lesson to be learned is set the LCD watch using the counter, at normal shop temperature. Give it to the customer to wear for two weeks. Calculate the error rate, and then readjust the watch for -1 times that error rate at normal shop temperature. -Chuck Harris (amateur watchmaker) EB4APL wrote: When LCD wristwatches became common in the seventies we, in the frequency and timing group of a space tracking facility, investigated the possibility of adjusting our new watches against our standard. We found that a a small copper plate, about 1 X 2 cm, resting against the display and connected to a scope probe was able to pick up enough 32 KHz energy to be displayed in the scope. Then connected the vertical output to an HP 5245L counter referenced to our standard and set the gate time to 10 seconds and got the frequency. We learned that the watch had to be worn in order to operate at the right temperature, the body acting as an oven, so you has to wear it backside in order to access the trimmer (yes, at that time those watches had and adjusting trimmer, maybe heritage from the mechanical ones, laser trimming arrived later). Our group became very popular and busy adjusting every watch our colleagues bought to a few seconds per month. Ignacio, EB4APL ___ 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] Don't use cheap cables -- a cautionary tale
This is a useful thread IMHO. Re the continuous beat note interference issue, I believe I've encountered this when evaluating a Datum1000B. At first I saw a periodic change in frequency of several E-10, the typical period was several hundred seconds. Turning off all the un needed gear in my lab except for a few ocxo's that i don't want to turn off and using double shielded RG400 cables without adapters for all the interconnections seemed to make the issue go away. All the outputs from the un used ocxo's were also terminated with bnc or sma terminators.Even the BNC T connectors I typically leave connected to the inputs of my HP5370B's (along with 50 ohm terminators) seemed to cause issues in this application. This issue has also prompted me to give up on my plans to move my GPSDO's from my radio room to my lab, as it's nice to be able to leave the GPSDO's running into a terminator vs having to shut them off. I've never really put much effort into tracking down the root cause of this issue but I suspect it is similar to what John mentioned. My FTS1050 (which IIRC is based on a datum 1000) doesn't seem to have this issue, building enclosures for my Datum1000's is on my post retirement to do list as I suspect running them without an enclosure may be contributing to this problem. As far as I know my BVA Ocxo is immune from this issue as well. Regards Mark Spencer Sent from my iPad ___ 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.
