Re: [time-nuts] simulation of interconnected clocks
On Sat, 30 Nov 2013 06:31:01 -0800 Jim Lux jim...@earthlink.net wrote: Recently, I've been looking at the variations of some human clocks which are millenia old: Galileo used his pulse as a timer for his famous roll balls down a ramp experimenet. I thought that some time-nuts might be interested in working with a clock that's a bit different than one depending on atomic vibrations, or motion within a crystal lattice. I don't know whether this is of any help to you, but some time ago i stumbled about some old lectures by Charles Peskin on the heart and to its chaotic self-synchronization [1]. If you are interested in the synchronisation phenomena in biological oscillators, i can recommend you [2]. Also a good read is [3] which gives a quite lengthy analysis on Kuramotos model [4]. Also a nice review paper is [5], which starts from Kuramoto and explains the current unsolved problems with coupled oscillators and their mathematical description. Attila Kinali [1] Mathematical aspects of heart physiology, by Peskin, 1975 http://math.nyu.edu/faculty/peskin/heartnotes/index.html [2] Synchronization of Pulse-Coupled Biological Oscillators by Mirollo and Strogatz, 1990 http://math.bd.psu.edu/faculty/stevens/MATH497K/Papers/Syncrhonization.pdf [3] The Kuramoto model: A simple paradigm for synchronization phenomena, by Acbron, Bonilla, Vincente, Ritort, Spigler, 2005 http://rmp.aps.org/abstract/RMP/v77/i1/p137_1 [4] Self-entrainment of a population of coupled non-linear oscillators by Kuramoto, 1975 http://www.springerlink.com/content/71073361941277h8/ [5] From Kuramoto to Crawford: exploring the onset of synchronization in populations of coupled oscillators, by Strogatz, 2000 http://www.sciencedirect.com/science/article/pii/S016727890944 -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Simulation of oscillator noise
Servus Wolfgang, On Sat, 30 Nov 2013 10:32:42 +0100 Wolfgang Wallner wolfgang-wall...@gmx.at wrote: At my institute (TU Vienna, Computer Engineering) there has been a bachelor thesis which dealt with simulation of IEEE 1588 in OMNeT++ (a discrete event simulator). But the assumptions where rather simple (both of the clock model and the implemented version of IEEE 1588). For my master thesis I would like to enhance both aspects. I would like to do a full implementation of IEEE 1588 and to use a more realistic clock model. I think you could easily do a PhD on this topic alone. Thus I would highly recommend to focus on one aspect only for your master thesis. For simplicity, i'd first use some numbers on a good OCXO. These are much better specified and measured than the cheaper ones. E.g. you can use the Oscilloquartz 8607 as reference. If what data is freely available online is not enough for you, try contacting the manufacturer. They always have better data available, but do not publish it (don't ask me why). But still, they are usually quite generous with handing this data out for specific projects. Using a good oscillator will also give you a chance to verify your model. It should still be close to what the simulation with an ideal oscillator. Check for any deviation and try to explain it from the model. If you cannot explain it, it might be a simulation artefact. From there, you can then start to degrade the oscillator model until it matches those of the oscillators you actually want to study. Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Simulation of oscillator noise
Hi Magnus, On Fri, 29 Nov 2013 17:42:25 +0100 Magnus Danielson mag...@rubidium.dyndns.org wrote: When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Yes. Because in the class of cheap AT cut oscillators, you dont worry about allan variance. The instability due to temperature dependence of your system is much higher than the temperature-free (in)stability. The ADEV becomes relevant only after you do at least a temperature compensation or temperature control. The specification for temperature variations is a poor excuse too. Some vendors have learned that the hard way. Could you explain a little bit what you mean here? I don't think i get exactly what you are hinting at. Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Simulation of oscillator noise
On 12/08/2013 11:46 AM, Attila Kinali wrote: Hi Magnus, On Fri, 29 Nov 2013 17:42:25 +0100 Magnus Danielson mag...@rubidium.dyndns.org wrote: When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Yes. Because in the class of cheap AT cut oscillators, you dont worry about allan variance. The instability due to temperature dependence of your system is much higher than the temperature-free (in)stability. The ADEV becomes relevant only after you do at least a temperature compensation or temperature control. The specification for temperature variations is a poor excuse too. Some vendors have learned that the hard way. Could you explain a little bit what you mean here? I don't think i get exactly what you are hinting at. Well. While staying within +/- 10 ppm over the temperature range may be one way of specifying the temperature dependence, it does not give you a good sense how it behaves at some particular temperature. Also, these are long-term dependence, but what happens when there is a quick change in temperature, what happens to frequency... and phase. Then we have drift properties. Let's put it another way. There is a reason cheap oscillators are cheap. 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] simulation of interconnected clocks
Heart rate depends on a feedback circuit through the autonomic nervous system. Microvascular disease (diabetes), denervation (heart transplant), and drugs can all alter the variabilility. There actaully is a large literatuee in fetal heart rate variability used to diagnoses fetal distress and precipirate energent cesarian section. Sent via the Samsung Galaxy S™ III, an ATT 4G LTE smartphone Original message From: Jim Lux jim...@earthlink.net Date: 11/30/2013 6:41 PM (GMT-05:00) To: time-nuts@febo.com Subject: Re: [time-nuts] simulation of interconnected clocks On 11/30/13 2:15 PM, Tom Van Baak wrote: Jim, Could you just replay real data instead of trying to generate simulated data? There's plenty of storage with Arduino or SD card shields. Attached is frequency and ADEV of my heart beat for 10 hours. You could do the same. In this case the flicker floor is just under 1e-1 from 10s to 10ks. One could do that. Or in a limited sense, have a shorter table which you play back repetitively. If you did some processing on your heartbeat data to remove the sinusoidal modulation from respiration, you might find the ADEV/phase noise is less. That's something I'm looking into. In my case, I need to be able to generate multiple different realistic targets. I could probably record a bunch of sequences and then play back different pieces of them. or use one person and have them breathe at different rates and depths. But an algorithmic approach is interesting. And even more interesting is being able to generate a particular pattern (using the model), and see if you can retrieve the model parameters using the device. Here's where I'm using it: http://www.jpl.nasa.gov/news/news.php?release=2013-281 http://www.jpl.nasa.gov/news/news.php?release=2013-290 http://www.jpl.nasa.gov/video/?id=1252 We use the model parameters to distinguish targets from one another (and targets from bystanders and the operator); and also to separate humans from other targets (oddly enough, that slowly rotating fan, or swinging grandfather clock pendulum have much lower 1/f noise than your heart). One finds as you delve into the physiology literature that they have exceedingly different ways to measure, describe, and model things than engineers do. In some cases it's because they're working from the biological structures that make it happen. In others, it's just because historically it's been described differently: often with reference to particular methods of recording the signal. It's kind of like how the Richter scale is in terms of the height of the trace in mm on a particular kind of seismograph. Someone goes out and records ECG data and they write the paper and say data was recorded using a Grass model X with the filter set at position 3, and since everyone in that field of research uses the same machines, they all know how it was recorded, and can duplicate it if needed. The signal processing details of the Grass Model X with filter set at Position 3 might be left as an exercise for the reader (or a letter to Al Grass at the Grass Instrument Company). The same thing happens in the nuclear instrumentation area, where everything is in terms of pulses and time domain processing, and you refer to a particular model of Ortec pre-amp, feeding some other model discriminator, finally feeding your multichannel analyzer (which name confused me, since it has only one input channel). The other thing is that a until recently, computers weren't used to analyze the data, so the analytical methods tend to favor those that are paper, pencil, and slide rule tractable. There's a lot of log/log plots with visually placed curve fits, with not a huge number of test subjects (20 subjects would be a lot in most of these papers). Finally, there might be a historical reason why decent math models aren't popular: The grand man of physiology was Carl Ludwig in Leipzig: he had hundreds of postgraduate students (Pavlov was one), but apparently he had little use for mathematical treatment of biological problems. Ludwig wrote the 1847 paper everyone cites as the beginning: Beitraege zur Kenntniss des Einflusses der Respirations bewegungen auf den Blutlauf im Aortensysteme. But hey, if your supervisor says math models aren't important, you're sure not going to argue with him, and someone of distinctly math modeling bent would likely find another place to study or field of study. So Ludwig casts a long shadow on published research, probably for 2 or 3 generations. Thanks to the miracle of the internet and big efforts to scan stuff this kind of thing is readily available. It's come a long ways since I had to hunt down a copy of Paschen's paper/thesis on high voltage breakdown as an actual printed copy and then photocopy it. http://archive.org/stream/beitrgezurkenn00hein#page/n55/mode/2up has some examples of data collected later in the 19th century from
Re: [time-nuts] simulation of interconnected clocks
On 12/01/2013 01:36 PM, paul.alfille wrote: Heart rate depends on a feedback circuit through the autonomic nervous system. Microvascular disease (diabetes), denervation (heart transplant), and drugs can all alter the variabilility. There actaully is a large literatuee in fetal heart rate variability used to diagnoses fetal distress and precipirate energent cesarian section. ___ 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] simulation of interconnected clocks
So, are we any closer to finding the body oscillator that lets us wake up just before the alarm goes off? Or could it be that we are awakened by the alarm but recognition of it is delayed? Bill Hawkins (currently dealing with a low, irregular heartbeat) ___ 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] Simulation of oscillator noise
Hello, thanks a lot for all your feedback (also in the other threads)! It will take some time to read reed through all your recommendations :) On 11/28/2013 08:18 PM, Attila Kinali wrote: On Thu, 28 Nov 2013 10:35:33 +0100 Wolfgang Wallner wolfgang-wall...@gmx.at wrote: I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. Hehe. Join the club. But treat carefully, this can become quite addictive ;-) Can you explain what you are exactly doing? You talk about noise, but only mention allan deviation. ADEV is the right tool to measure stability, but not so much phase noise. The interest comes from IEEE 1588, which is an interesting standard, but the equipment is quite expensive (a single switch with transparent clock support for 1000$). This means it is hard to estimated what could be achieved with 1588, as it is rather impossible to just buy some devices and try it out. Questions which would be interesting are things like: *) what synchronization interval is need to achieve a specific precision, and where are the limits *) how does a long daisy chain behave (with/without syntonization in each hop) *) what happens when a link breaks and comes up some time later (how far will the parts drift away) At my institute (TU Vienna, Computer Engineering) there has been a bachelor thesis which dealt with simulation of IEEE 1588 in OMNeT++ (a discrete event simulator). But the assumptions where rather simple (both of the clock model and the implemented version of IEEE 1588). For my master thesis I would like to enhance both aspects. I would like to do a full implementation of IEEE 1588 and to use a more realistic clock model. Implementing IEEE 1588 is rather straight forward. The standard is easy to read, and it is not rocket science to implement this it in C++. But as already stated in my first message, I underestimated how hard it would be to get a realistic clock model. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? What part of the oscillator? Noise of the feedback electronics? Noise of the output stage? Noise from environmental factors? Noise intrinsic to the quartz crystal resonator? How accurate do you want the model to be? How do you simulate the complete oscillator? (this is a big topic of its own, and definitly not easy) Did you read Enrico Runbiolas Book Phase Noise and Frequency Stability in Oscillators? If not, you should start with that. It gives a nice overview of all the basics you need to understand this topic. Gangepain did a lot of research on noise sources and stability of quartz oscillators. You might want to look up papers from him. (there was somewhere a collection of them) A couple of weeks ago, i did a literature search on various stuff around low noise/high stability oscillators. But i didn't have the time to sort those papers yet, much less read them. But i can search for things in there, if you tell me what you are looking for. I have read different kinds of papers up to now, but non of them was really what I was looking for: What are you looking for? *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. Well, Thieles group does mostly wireless sensor networks (catually most of the TIK institute does wireless sensor networks in one form or another). Their use for an accurate clock is to minimize the on time of the RF circuit in order to minimize power consumption. IIRC their goal was to get down from synchronisation window of 1s to 0.1 on a time scale of a couple of minutes to a couple of hours. And the whole calculation had to be simple enough to be done on an 8bit ATMega while not taking considerable computation time. These requirements lead to a rather simple model of clock deviation. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. I dont know these two papers, but they dont look too bad. As for the age. Most of the theoretical work on quartz oscillators was done in the 70s and 80s. Also most of the books on quartz oscillators are from that time. There are
Re: [time-nuts] Simulation of oscillator noise
Hi Wolfgang, On 11/30/2013 10:32 AM, Wolfgang Wallner wrote: Hello, thanks a lot for all your feedback (also in the other threads)! It will take some time to read reed through all your recommendations :) On 11/28/2013 08:18 PM, Attila Kinali wrote: On Thu, 28 Nov 2013 10:35:33 +0100 Wolfgang Wallner wolfgang-wall...@gmx.at wrote: I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. Hehe. Join the club. But treat carefully, this can become quite addictive ;-) Can you explain what you are exactly doing? You talk about noise, but only mention allan deviation. ADEV is the right tool to measure stability, but not so much phase noise. The interest comes from IEEE 1588, which is an interesting standard, but the equipment is quite expensive (a single switch with transparent clock support for 1000$). This means it is hard to estimated what could be achieved with 1588, as it is rather impossible to just buy some devices and try it out. Questions which would be interesting are things like: *) what synchronization interval is need to achieve a specific precision, and where are the limits *) how does a long daisy chain behave (with/without syntonization in each hop) *) what happens when a link breaks and comes up some time later (how far will the parts drift away) At my institute (TU Vienna, Computer Engineering) there has been a bachelor thesis which dealt with simulation of IEEE 1588 in OMNeT++ (a discrete event simulator). But the assumptions where rather simple (both of the clock model and the implemented version of IEEE 1588). For my master thesis I would like to enhance both aspects. I would like to do a full implementation of IEEE 1588 and to use a more realistic clock model. Implementing IEEE 1588 is rather straight forward. The standard is easy to read, and it is not rocket science to implement this it in C++. But as already stated in my first message, I underestimated how hard it would be to get a realistic clock model. It's a difficult topic because: 1) There is no defined clock model defined in IEEE 1588, so there is no way to generally specify what a 1588 device will do. I've checked this with one of the core 1588 guys and he agrees. 2) There is no defined network jitter model. You need to consider if equipment is 1588 aware or not, and it may be traffic load dependent, and there is a wide range of behaviors which does not fit normal noises. For 1588 aware switches and routers which works well, a first degree damping can be expected, but it is not perfect. The systematic behavior to low-frequency noise will leak through. The best you can do is build a few fair models and test with a few different noise-characteristics and see what they will do. Remember that it is not just the noise sources of your oscillator, you have systematic effects to care about, such as aging, initial frequency offset, initial phase offset, temperature dependence, PLL parameters etc. etc. 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] simulation of interconnected clocks
On 11/30/13 2:15 PM, Tom Van Baak wrote: Jim, Could you just replay real data instead of trying to generate simulated data? There's plenty of storage with Arduino or SD card shields. Attached is frequency and ADEV of my heart beat for 10 hours. You could do the same. In this case the flicker floor is just under 1e-1 from 10s to 10ks. One could do that. Or in a limited sense, have a shorter table which you play back repetitively. If you did some processing on your heartbeat data to remove the sinusoidal modulation from respiration, you might find the ADEV/phase noise is less. That's something I'm looking into. In my case, I need to be able to generate multiple different realistic targets. I could probably record a bunch of sequences and then play back different pieces of them. or use one person and have them breathe at different rates and depths. But an algorithmic approach is interesting. And even more interesting is being able to generate a particular pattern (using the model), and see if you can retrieve the model parameters using the device. Here's where I'm using it: http://www.jpl.nasa.gov/news/news.php?release=2013-281 http://www.jpl.nasa.gov/news/news.php?release=2013-290 http://www.jpl.nasa.gov/video/?id=1252 We use the model parameters to distinguish targets from one another (and targets from bystanders and the operator); and also to separate humans from other targets (oddly enough, that slowly rotating fan, or swinging grandfather clock pendulum have much lower 1/f noise than your heart). One finds as you delve into the physiology literature that they have exceedingly different ways to measure, describe, and model things than engineers do. In some cases it's because they're working from the biological structures that make it happen. In others, it's just because historically it's been described differently: often with reference to particular methods of recording the signal. It's kind of like how the Richter scale is in terms of the height of the trace in mm on a particular kind of seismograph. Someone goes out and records ECG data and they write the paper and say data was recorded using a Grass model X with the filter set at position 3, and since everyone in that field of research uses the same machines, they all know how it was recorded, and can duplicate it if needed. The signal processing details of the Grass Model X with filter set at Position 3 might be left as an exercise for the reader (or a letter to Al Grass at the Grass Instrument Company). The same thing happens in the nuclear instrumentation area, where everything is in terms of pulses and time domain processing, and you refer to a particular model of Ortec pre-amp, feeding some other model discriminator, finally feeding your multichannel analyzer (which name confused me, since it has only one input channel). The other thing is that a until recently, computers weren't used to analyze the data, so the analytical methods tend to favor those that are paper, pencil, and slide rule tractable. There's a lot of log/log plots with visually placed curve fits, with not a huge number of test subjects (20 subjects would be a lot in most of these papers). Finally, there might be a historical reason why decent math models aren't popular: The grand man of physiology was Carl Ludwig in Leipzig: he had hundreds of postgraduate students (Pavlov was one), but apparently he had little use for mathematical treatment of biological problems. Ludwig wrote the 1847 paper everyone cites as the beginning: Beitraege zur Kenntniss des Einflusses der Respirations bewegungen auf den Blutlauf im Aortensysteme. But hey, if your supervisor says math models aren't important, you're sure not going to argue with him, and someone of distinctly math modeling bent would likely find another place to study or field of study. So Ludwig casts a long shadow on published research, probably for 2 or 3 generations. Thanks to the miracle of the internet and big efforts to scan stuff this kind of thing is readily available. It's come a long ways since I had to hunt down a copy of Paschen's paper/thesis on high voltage breakdown as an actual printed copy and then photocopy it. http://archive.org/stream/beitrgezurkenn00hein#page/n55/mode/2up has some examples of data collected later in the 19th century from dogs and cats. ___ 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] simulation of interconnected clocks
On 11/30/13 2:15 PM, Tom Van Baak wrote: Jim, Could you just replay real data instead of trying to generate simulated data? There's plenty of storage with Arduino or SD card shields. Attached is frequency and ADEV of my heart beat for 10 hours. You could do the same. In this case the flicker floor is just under 1e-1 from 10s to 10ks. The flat zero slope adev shows the basic 1/f characteristic reported in the literature. There's been quite a few people who have hooked up monitors to people for 24 hours or more and found that the power spectrum of heart rate follows 1/f from about 0.3 Hz down 4 decades at least. I'm not sure what the ADEV/Power spectrum of respiration rate would be, since it's mostly determined by what the person is doing. Power spectrum (averaged over a long time) would probably be more a histogram of level of physical 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] simulation of interconnected clocks
t...@leapsecond.com said: Attached is frequency and ADEV of my heart beat for 10 hours. Neat. What did you use to collect the raw data? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] simulation of interconnected clocks
On 11/30/13 5:33 PM, Hal Murray wrote: t...@leapsecond.com said: Attached is frequency and ADEV of my heart beat for 10 hours. Neat. What did you use to collect the raw data? There's a few Arduino/Sparkfun/Adafruit widgets out there that receive the signals from off the shelf Polar heart rate monitors. I had a grad student last summer build a box to log heart beats using photoplethysmography (photocell sensing blood flow in fingertip). He used a widget from one of the dealers that has the analog circuitry to buffer the optical sensor. If I were collecting it on a long term (many hours) basis, I'd go with ECG based approaches (which is what the Polar sensors use), but with stick on electrodes. Motion artifacts are a big problem. Holter is the big name in commercial ECG loggers, but they're real pricey (being FDA approved medical devices and all). Microwave monitoring (radar) is a good standoff way to measure heartbeats, but only works in fixed locations (e.g. I can set it up in my office, in my car, or a room at home, and collect data, but it doesn't work well when you're out walking around). If you get one of those microwave Doppler door sensors at 10.5 or 24 GHz, you can get a good heartbeat signal from them. ___ 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] simulation of interconnected clocks
Neat. What did you use to collect the raw data? Hi Hal, The pulse data came from a sports chest-strap heart rate monitor, made by Polar. See the 10^-1 page of the PDF at http://leapsecond.com/ten/ There are two data formats, non-coded (T34) and coded (T31). More info: https://www.sparkfun.com/products/8661 https://www.sparkfun.com/datasheets/Wireless/General/RMCM01.pdf http://danjuliodesigns.com/sparkfun/sparkfun.html http://danjuliodesigns.com/sparkfun/hrmi_assets/hrmi.pdf https://www.adafruit.com/products/1077 http://learn.parallax.com/KickStart/28048 /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] Simulation of oscillator noise
Hello Wolfgang, lots of interesting reading about oscillator noise: http://rubiola.org/index.html There are also some phase noise related publications from Ulrich L. Rohde: http://www.tu-cottbus.de/fakultaet3/de/fakultaet/institute/stiftung/prof-dr-ing-habil-dr-hc-mult-ulrich-l-rohde/technical-publications.html Best regards, Adrian Wolfgang Wallner schrieb: Hello Time-Nuts community, I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? I have read different kinds of papers up to now, but non of them was really what I was looking for: *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. 2) Do you know any public data samples of the allan variance of a real oscillators? When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Best regards, Wolfgang Wallner PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. ___ 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] Simulation of oscillator noise
On 11/28/13 1:35 AM, Wolfgang Wallner wrote: Hello Time-Nuts community, I'm interested in the simulation of oscillator noise (especially in discrete event simulators). PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. I think it's the right place.. There's plenty of Allan deviation plots and data here for just about any kind of oscillator you care to name. One way to generate realistic spectra is to take white noise from a random number generator and run it through a filter which has the right shape (e.g. 1/f, etc.). Essentially this is implementing the Leeson model explicitly. A year or so ago, I was looking for a similar thing to simulate human heartbeats (which have a 1/f characteristic, just like other oscillators). http://www.febo.com/pipermail/time-nuts/2013-February/074505.html see also http://paulbourke.net/fractals/noise/ ___ 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] Simulation of oscillator noise
Ciao, On Thu, 28 Nov 2013 14:03:06 +0100 Azelio Boriani azelio.bori...@screen.it wrote: http://horology.jpl.nasa.gov/papers/FlfmSimPtti.pdf This host has ceased to exist. Can you tell us the title of the paper and the names of its authors? Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Simulation of oscillator noise
On Thu, 28 Nov 2013 10:35:33 +0100 Wolfgang Wallner wolfgang-wall...@gmx.at wrote: I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. Hehe. Join the club. But treat carefully, this can become quite addictive ;-) Can you explain what you are exactly doing? You talk about noise, but only mention allan deviation. ADEV is the right tool to measure stability, but not so much phase noise. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? What part of the oscillator? Noise of the feedback electronics? Noise of the output stage? Noise from environmental factors? Noise intrinsic to the quartz crystal resonator? How accurate do you want the model to be? How do you simulate the complete oscillator? (this is a big topic of its own, and definitly not easy) Did you read Enrico Runbiolas Book Phase Noise and Frequency Stability in Oscillators? If not, you should start with that. It gives a nice overview of all the basics you need to understand this topic. Gangepain did a lot of research on noise sources and stability of quartz oscillators. You might want to look up papers from him. (there was somewhere a collection of them) A couple of weeks ago, i did a literature search on various stuff around low noise/high stability oscillators. But i didn't have the time to sort those papers yet, much less read them. But i can search for things in there, if you tell me what you are looking for. I have read different kinds of papers up to now, but non of them was really what I was looking for: What are you looking for? *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. Well, Thieles group does mostly wireless sensor networks (catually most of the TIK institute does wireless sensor networks in one form or another). Their use for an accurate clock is to minimize the on time of the RF circuit in order to minimize power consumption. IIRC their goal was to get down from synchronisation window of 1s to 0.1 on a time scale of a couple of minutes to a couple of hours. And the whole calculation had to be simple enough to be done on an 8bit ATMega while not taking considerable computation time. These requirements lead to a rather simple model of clock deviation. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. I dont know these two papers, but they dont look too bad. As for the age. Most of the theoretical work on quartz oscillators was done in the 70s and 80s. Also most of the books on quartz oscillators are from that time. There are very few books from the 90s and later. 2) Do you know any public data samples of the allan variance of a real oscillators? febo.com (John Ackermann) and leapsecond.com (Tom van Baak) have both some data on various crystall oscillators. When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Yes. Because in the class of cheap AT cut oscillators, you dont worry about allan variance. The instability due to temperature dependence of your system is much higher than the temperature-free (in)stability. The ADEV becomes relevant only after you do at least a temperature compensation or temperature control. PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. Don't worry, you are at the right place :-) Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Simulation of oscillator noise
Wolfgang, A colleague of mine wrote this simulator based on a multirate filterbank: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=arnumber=5461653queryText%3Dm+brooker+phase+noise Since you are in the academia I'd assume you'll be able to access it? Cheers, Stephan. On 28 November 2013 11:35, Wolfgang Wallner wolfgang-wall...@gmx.at wrote: Hello Time-Nuts community, I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? I have read different kinds of papers up to now, but non of them was really what I was looking for: *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. 2) Do you know any public data samples of the allan variance of a real oscillators? When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Best regards, Wolfgang Wallner PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. ___ 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] Simulation of oscillator noise
Unfortunately that was a contribution from Magnus in 2010 (see www.febo.com/pipermail/time-nuts/2010-April/046932.html ) that I have simply reported without verifying the link and found that link unusable after sending the message. My best guess is this: http://www.crya.unam.mx/radiolab/recursos/Allan/Kasdin-Walter.pdf based on a search on FLFM (flicker of frequency). On Thu, Nov 28, 2013 at 8:22 PM, Attila Kinali att...@kinali.ch wrote: Ciao, On Thu, 28 Nov 2013 14:03:06 +0100 Azelio Boriani azelio.bori...@screen.it wrote: http://horology.jpl.nasa.gov/papers/FlfmSimPtti.pdf This host has ceased to exist. Can you tell us the title of the paper and the names of its authors? Attila Kinali -- 1.) Write everything down. 2.) Reduce to the essential. 3.) Stop and question. -- The Habits of Highly Boring People, Chris Sauve ___ 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] Simulation of oscillator noise
On 11/29/13 5:56 AM, Azelio Boriani wrote: Unfortunately that was a contribution from Magnus in 2010 (see www.febo.com/pipermail/time-nuts/2010-April/046932.html ) that I have simply reported without verifying the link and found that link unusable after sending the message. My best guess is this: http://www.crya.unam.mx/radiolab/recursos/Allan/Kasdin-Walter.pdf based on a search on FLFM (flicker of frequency). one limitation of the Kasdin-Walter method is that it is batch mode, and doesn't lend itself to an implementation which is continuous. The paper does have a nice discussion of why the white noise into a filter technique doesn't work very well if the slopes you need aren't integer powers of frequency. Integer powers in frequency correspond to rational functions in filter characteristics, which are straightforward, but how do you make a 1.5th order filter section or half a pole or zero? The fractal literature, though, may provide mechanisms that might be useful. ___ 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] Simulation of oscillator noise
On 11/29/2013 04:11 PM, Jim Lux wrote: On 11/29/13 5:56 AM, Azelio Boriani wrote: Unfortunately that was a contribution from Magnus in 2010 (see www.febo.com/pipermail/time-nuts/2010-April/046932.html ) that I have simply reported without verifying the link and found that link unusable after sending the message. My best guess is this: http://www.crya.unam.mx/radiolab/recursos/Allan/Kasdin-Walter.pdf based on a search on FLFM (flicker of frequency). one limitation of the Kasdin-Walter method is that it is batch mode, and doesn't lend itself to an implementation which is continuous. The paper does have a nice discussion of why the white noise into a filter technique doesn't work very well if the slopes you need aren't integer powers of frequency. Integer powers in frequency correspond to rational functions in filter characteristics, which are straightforward, but how do you make a 1.5th order filter section or half a pole or zero? The fractal literature, though, may provide mechanisms that might be useful. Actually, NIST (or actually this was in it's NBS days) did a few good articles, comparing the Mandelbrot simulation method with their filter method. Turns out that you need to dimension the filter to the simulation length, as the number of lead-lag sections needs to cover the range where 1/f slope is needed and then the density of them (lead-lag pole/zeros per decade) will control how close it will approximate, that is, how little pass-band ripple there is from the ideal. Also, you need to apply the corrections to start the filter up in the correct state. It's non-trivial to do well. There are many many methods to do this. Everyone has a favorite. 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] Simulation of oscillator noise
On 11/28/2013 08:18 PM, Attila Kinali wrote: On Thu, 28 Nov 2013 10:35:33 +0100 Wolfgang Wallner wolfgang-wall...@gmx.at wrote: I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. Hehe. Join the club. But treat carefully, this can become quite addictive ;-) Can you explain what you are exactly doing? You talk about noise, but only mention allan deviation. ADEV is the right tool to measure stability, but not so much phase noise. On the contrary, ADEV (and MDEV even more so) is designed to separate noise-types such that they can be estimated separately. It is only of lately that you can use both phase-noise plots and timer-based ADEV/MDEV plots to achieve the same thing, not that the phase-noise characteristics have been hard to estimate from, but rather that it has been hard to achieve qualitative measures for precision sources such that all noise-forms can be used for estimation. This have been easier in the TIC-driven measurement. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? What part of the oscillator? Noise of the feedback electronics? Noise of the output stage? Noise from environmental factors? Noise intrinsic to the quartz crystal resonator? How accurate do you want the model to be? How do you simulate the complete oscillator? (this is a big topic of its own, and definitly not easy) Did you read Enrico Runbiolas Book Phase Noise and Frequency Stability in Oscillators? If not, you should start with that. It gives a nice overview of all the basics you need to understand this topic. Strongly recommended reading. His view is phase-noise driven. I think one should study both sides of the coin since they have different benefits and different usages. Gangepain did a lot of research on noise sources and stability of quartz oscillators. You might want to look up papers from him. (there was somewhere a collection of them) A couple of weeks ago, i did a literature search on various stuff around low noise/high stability oscillators. But i didn't have the time to sort those papers yet, much less read them. But i can search for things in there, if you tell me what you are looking for. I have read different kinds of papers up to now, but non of them was really what I was looking for: What are you looking for? *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. Well, Thieles group does mostly wireless sensor networks (catually most of the TIK institute does wireless sensor networks in one form or another). Their use for an accurate clock is to minimize the on time of the RF circuit in order to minimize power consumption. IIRC their goal was to get down from synchronisation window of 1s to 0.1 on a time scale of a couple of minutes to a couple of hours. And the whole calculation had to be simple enough to be done on an 8bit ATMega while not taking considerable computation time. These requirements lead to a rather simple model of clock deviation. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. I dont know these two papers, but they dont look too bad. As for the age. Most of the theoretical work on quartz oscillators was done in the 70s and 80s. Also most of the books on quartz oscillators are from that time. There are very few books from the 90s and later. If you want more modern papers on simulation of noise, then there is a few from JPL that applies, but the site where unfortunatly dropped in one of the server-roundups. 2) Do you know any public data samples of the allan variance of a real oscillators? febo.com (John Ackermann) and leapsecond.com (Tom van Baak) have both some data on various crystall oscillators. When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Yes. Because in the class of cheap AT cut oscillators, you dont worry about allan variance. The instability due to temperature dependence of your system is much higher than the temperature-free (in)stability. The ADEV
Re: [time-nuts] Simulation of oscillator noise
On 11/29/13 8:50 AM, Magnus Danielson wrote: On 11/29/2013 04:11 PM, Jim Lux wrote: On 11/29/13 5:56 AM, Azelio Boriani wrote: Unfortunately that was a contribution from Magnus in 2010 (see www.febo.com/pipermail/time-nuts/2010-April/046932.html ) that I have simply reported without verifying the link and found that link unusable after sending the message. My best guess is this: http://www.crya.unam.mx/radiolab/recursos/Allan/Kasdin-Walter.pdf based on a search on FLFM (flicker of frequency). one limitation of the Kasdin-Walter method is that it is batch mode, and doesn't lend itself to an implementation which is continuous. The paper does have a nice discussion of why the white noise into a filter technique doesn't work very well if the slopes you need aren't integer powers of frequency. Integer powers in frequency correspond to rational functions in filter characteristics, which are straightforward, but how do you make a 1.5th order filter section or half a pole or zero? The fractal literature, though, may provide mechanisms that might be useful. Actually, NIST (or actually this was in it's NBS days) did a few good articles, comparing the Mandelbrot simulation method with their filter method. Turns out that you need to dimension the filter to the simulation length, as the number of lead-lag sections needs to cover the range where 1/f slope is needed and then the density of them (lead-lag pole/zeros per decade) will control how close it will approximate, that is, how little pass-band ripple there is from the ideal. Also, you need to apply the corrections to start the filter up in the correct state. That's essentially what the Kasdin-Walter paper talks about. The number of taps/sections is adjusted to approximate whatever curve you want well enough. Then, they sort of shunt all that with an FFT based method.. Generate white noise, filter it with a FFT convolution scheme where you've loaded the bins of the FFT with the desired power spectrum. It's non-trivial to do well. And, I suspect, non-trivial to do with low computational complexity. There are many many methods to do this. Everyone has a favorite. No doubt about 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] Simulation of oscillator noise
Jim, On 11/29/2013 07:27 PM, Jim Lux wrote: On 11/29/13 8:50 AM, Magnus Danielson wrote: On 11/29/2013 04:11 PM, Jim Lux wrote: On 11/29/13 5:56 AM, Azelio Boriani wrote: Unfortunately that was a contribution from Magnus in 2010 (see www.febo.com/pipermail/time-nuts/2010-April/046932.html ) that I have simply reported without verifying the link and found that link unusable after sending the message. My best guess is this: http://www.crya.unam.mx/radiolab/recursos/Allan/Kasdin-Walter.pdf based on a search on FLFM (flicker of frequency). one limitation of the Kasdin-Walter method is that it is batch mode, and doesn't lend itself to an implementation which is continuous. The paper does have a nice discussion of why the white noise into a filter technique doesn't work very well if the slopes you need aren't integer powers of frequency. Integer powers in frequency correspond to rational functions in filter characteristics, which are straightforward, but how do you make a 1.5th order filter section or half a pole or zero? The fractal literature, though, may provide mechanisms that might be useful. Actually, NIST (or actually this was in it's NBS days) did a few good articles, comparing the Mandelbrot simulation method with their filter method. Turns out that you need to dimension the filter to the simulation length, as the number of lead-lag sections needs to cover the range where 1/f slope is needed and then the density of them (lead-lag pole/zeros per decade) will control how close it will approximate, that is, how little pass-band ripple there is from the ideal. Also, you need to apply the corrections to start the filter up in the correct state. That's essentially what the Kasdin-Walter paper talks about. The number of taps/sections is adjusted to approximate whatever curve you want well enough. ... which fails to reference the right papers: NBS Report 9284 The generation and recognition of flicker noise by Jim Barnes. http://tf.boulder.nist.gov/general/pdf/190.pdf NBS Technical Note 604 Efficient Numerical and Analog Modeling of Flicker Noise Processes by Jim Barnes. http://tf.nist.gov/timefreq/general/pdf/29.pdf Jim Barnes and Chuck Greenhall Large sample simulation of flicker noise http://tycho.usno.navy.mil/ptti/1987papers/Vol 19_19.pdf This one has nice plots about different amount of stages, however you *really* want the follow-up correction and addenda http://tycho.usno.navy.mil/ptti/1992papers/Vol 24_44.pdf This is the W. Riley list of references: http://www.wriley.com/Refs.htm Then, they sort of shunt all that with an FFT based method.. Generate white noise, filter it with a FFT convolution scheme where you've loaded the bins of the FFT with the desired power spectrum. The paper which is filename is FlfmSimPtti.pdf has the propper title FFT-Based Methods for Simulating Flicker FM by Charles A. Greenhall of JPL. Should have remembered Chuck's name in the previous post, but I was tired. The Kasdin-Walter paper was proposed as a replacement, there are similarities, but do read Chuck's fine paper! This Greenhall paper is found here: http://trs-new.jpl.nasa.gov/dspace/handle/2014/11024 http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/11024/1/02-2912.pdf It's non-trivial to do well. And, I suspect, non-trivial to do with low computational complexity. It is. Hence it is important to read-up. There are many many methods to do this. Everyone has a favorite. No doubt about it. Not sure which is my favorite just yet. 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] Simulation of oscillator noise
Hello Time-Nuts community, I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? I have read different kinds of papers up to now, but non of them was really what I was looking for: *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. 2) Do you know any public data samples of the allan variance of a real oscillators? When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Best regards, Wolfgang Wallner PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. ___ 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] Simulation of oscillator noise
From an old time-nuts post (by Magnus): try these http://tycho.usno.navy.mil/ptti/1987/Vol%2019_19.pdf http://horology.jpl.nasa.gov/papers/FlfmSimPtti.pdf and here http://libra.msra.cn/Publication/50096626/a-new-time-domain-model-of-precise-clock-noise On Thu, Nov 28, 2013 at 10:35 AM, Wolfgang Wallner wolfgang-wall...@gmx.at wrote: Hello Time-Nuts community, I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? I have read different kinds of papers up to now, but non of them was really what I was looking for: *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. 2) Do you know any public data samples of the allan variance of a real oscillators? When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Best regards, Wolfgang Wallner PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. ___ 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] Simulation of oscillator noise
The link http://tycho.usno.navy.mil/ptti/1987/Vol%2019_19.pdf doesn't work, use instead: http://tycho.usno.navy.mil/ptti/1987papers/Vol%2019_19.pdf On Thu, Nov 28, 2013 at 2:03 PM, Azelio Boriani azelio.bori...@screen.it wrote: From an old time-nuts post (by Magnus): try these http://tycho.usno.navy.mil/ptti/1987/Vol%2019_19.pdf http://horology.jpl.nasa.gov/papers/FlfmSimPtti.pdf and here http://libra.msra.cn/Publication/50096626/a-new-time-domain-model-of-precise-clock-noise On Thu, Nov 28, 2013 at 10:35 AM, Wolfgang Wallner wolfgang-wall...@gmx.at wrote: Hello Time-Nuts community, I'm interested in the simulation of oscillator noise (especially in discrete event simulators). I came across this topic as part of the literature research for my master's thesis, and have to admit that I really underestimated how complex this topic is. In the past weeks, I have spent a lot of time reading about different kinds of variances, and I think I have a basic understanding now. I would like to ask you two questions: 1) Do you have any advice for me on what papers to read concerning oscillator noise simulation? I have read different kinds of papers up to now, but non of them was really what I was looking for: *) One of the papers I have read is Accurate Clock Models for Simulating Wireless Sensor Networks by Ferrari, Meier and Thiele. But I don't think their simple model is of any use, as they completely ignore the typical allan variance of oscillators. *) On the other hand, the paper Achieving a Realistic Notion of Time in Discrete Event Simulation by Gaderer, Nagy, Loschmidt and Sauter describes a very realistic model, but they keep the implementation details to themselves. *) What could be of use for my purpose could be Simulation of Oscillator Noise by Barnes, but as it is from 1988 it is quite dated. 2) Do you know any public data samples of the allan variance of a real oscillators? When I look in the data sheets of oscillator that I find on the internet, they only have precision estimates like 1ppm or 1ppb, but no detailed allan variance graphs. Best regards, Wolfgang Wallner PS: When I use the word oscillator I mean the cheap quartz oscillators as found in typical consumer electronic stuff. PPS: I'm not sure if this mailing-list is the right place to ask my questions, as simulation is not listed in your mailing-list topics. Sorry if this mail is off-topic. ___ 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] Simulation of oscillator noise
Wolfgang, There's a large list of papers at William Riley's site that should be of interest to you: http://www.wriley.com/ He also has copies of the NBS test data. Given you're working on a masters thesis you can probably qualify for a student discount on his Stable32 software; it includes the ability to generate 5 types of synthetic oscillator noise from alpha -2 to alpha +2. Documentation is on his site. I have lots of raw oscillator data sets that you're welcome to look at. Let me know what sort of oscillator you're interested in. See also: http://leapsecond.com/pages/gpsdo-sim/ /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] Simulation
Hi Bob yes that was a point raised by Prof Nat Sokal after I published some data, or rather he pointed out it happened in RF amps. I guess if you take an used PA transistor out of service and measure it you might find the base emitter junction very leaky, but does few mA of leakage matter so much in a low impedance high drive power circuit. Reliability asks does it do the job it was designed for not is it as good as new now Alan G3NYK - Original Message - From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 15, 2010 1:33 AM Subject: Re: [time-nuts] Simulation Hi Simulation might or might not have helped. 1) Was Vbe breakdown even included in the Spice model 2) If so did it ring bells (rare) or did it just clip without error ( common ) 3) Would the same designer who didn't understand it in the first place have seen it clipping at -5 and concluded looks to be in spec at -5 4) Would any of it be reviewed in light of the new transistor or was the guy on another project by then My favorite in the absolute max Vbe category is the typical class C RF amp. Look at the spec, check a few thousand working boards. Scratch head and move on. Lots of reverse bias on the base and they run forever. Bob ___ 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] Simulation
On 8/14/2010 2:56 PM, J. Forster wrote: On 8/14/2010 10:08 AM, J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John This is, easily said, a wonderful goal, and absolute fantasy. It's optimistic at best to expect someone to anticipate all contingencies. It's certainly good practice to specific critical parameters, but it's rarely makes economic sense to specify every possible detail. OK, important uncontrolled parameters. For example, I'd consider things like hFE; VCEsat; VCBO, fT and others important, but not the package capacitance in a low frequency transistor. There are clearly unimportant parameters and essentially irrelevant ones. That's where experience and good judgement comes in. If your circuit is not stable with a high fT part, that needs to be tested or the design fixed. Right, but the definition of high ft varies over time. Few reasonable designers as recently as 10 years ago would have anticipated the ft of today's CMOS processes. It's also likely they wouldn't have expected their designs to have lasted 10 years, and the vast majority haven't. Oddly enough, it seems like most of the really long life designs are the lower volume ones. These are usally the same ones that won't justify extensive up front analysis and cost unless they are DoD or aerospace applications. As to relying upon unspecified parameters, most datasheets are woefully incomplete. If you are going to use any significant number parts, it's unlikely that you'll be able to get everything specified, much less get compliance commitments for each parameter. Few vendors are willing to do the testing required to guarantee a substantial number of parameters, and the simple reason is no one is willing to pay for it. If your design is that critical, you may have to do incoming inspectrion/selection or send the parts to a company that does. But the portion of the discussion that is the root of this branch was precisely about designers being surprised by dramatic and unanticipated changes in component performance. Few rational companies are going to test for parameters in that category. I think we are almost making the same point here. Certainly we agree. My point is that there is an economic tradeoff. There are a number of parameters that are critical to any circuit's operation that it's reasonable to decide are not likely to vary outside critical parameters. It makes no economic sense to test these. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Simulation
It depends on whether the leakage continues to rise or stabilizes after a burn in period. -John Hi Bob yes that was a point raised by Prof Nat Sokal after I published some data, or rather he pointed out it happened in RF amps. I guess if you take an used PA transistor out of service and measure it you might find the base emitter junction very leaky, but does few mA of leakage matter so much in a low impedance high drive power circuit. Reliability asks does it do the job it was designed for not is it as good as new now Alan G3NYK - Original Message - From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 15, 2010 1:33 AM Subject: Re: [time-nuts] Simulation Hi Simulation might or might not have helped. 1) Was Vbe breakdown even included in the Spice model 2) If so did it ring bells (rare) or did it just clip without error ( common ) 3) Would the same designer who didn't understand it in the first place have seen it clipping at -5 and concluded looks to be in spec at -5 4) Would any of it be reviewed in light of the new transistor or was the guy on another project by then My favorite in the absolute max Vbe category is the typical class C RF amp. Look at the spec, check a few thousand working boards. Scratch head and move on. Lots of reverse bias on the base and they run forever. Bob ___ 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] Simulation
J. Forster wrote: It depends on whether the leakage continues to rise or stabilizes after a burn in period. -John Hi Bob yes that was a point raised by Prof Nat Sokal after I published some data, or rather he pointed out it happened in RF amps. I guess if you take an used PA transistor out of service and measure it you might find the base emitter junction very leaky, but does few mA of leakage matter so much in a low impedance high drive power circuit. Reliability asks does it do the job it was designed for not is it as good as new now Alan We get into the argument about still works ok in the circuit vs doesn't meet databook specs all the time at work. To some folks, not meet datasheet = failure, while if you have a circuit that needs a gain of 10, and the part has a gain of 1000, and degrades to 500, it's hardly failed. And rarely, do you have the budget or time to do a real life test to prove it experimentally. In radiation environments, it's more of a continuous aging effect.. more dose, more leakage. And what drives the conflict between designer and reliability guys is that the effect isn't particularly predictable, particularly between lots (because it's not something controlled in the process) (which makes life testing all that much more fun) ___ 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] Simulation
On 08/16/2010 02:16 AM, jimlux wrote: We get into the argument about still works ok in the circuit vs doesn't meet databook specs all the time at work. To some folks, not meet datasheet = failure, while if you have a circuit that needs a gain of 10, and the part has a gain of 1000, and degrades to 500, it's hardly failed. And rarely, do you have the budget or time to do a real life test to prove it experimentally. In radiation environments, it's more of a continuous aging effect.. more dose, more leakage. And what drives the conflict between designer and reliability guys is that the effect isn't particularly predictable, particularly between lots (because it's not something controlled in the process) (which makes life testing all that much more fun) But armed with the knowledge of what parameters do degrade, you may do simulations of various grades of degradation and show that with the current knowledge of degradation and assumptions on its effects and degrees, it is reasonable to expect functionality. Right? Simulation can be off assistance, if used wisely... (or a tool of self deception if not used wisely) 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] Simulation
Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. Bob ___ 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] Simulation
I have ALWAYS distrusted simulation and computer modeling. And I used to teach the stuff. GIGO. 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 -John === Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. Bob ___ 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] Simulation
Bob Camp wrote: Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. there are also designs that depend on non-data-sheet performance of particular devices. There's a very low noise, very low leakage fet popular in charge amplifiers. It has a JEDEC 2N number (which I can't remember off hand), but only the ones from one particular company (in England) actually work in the circuits, and even then, there's some hand selection involved. ___ 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] Simulation
FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John === Bob Camp wrote: Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. there are also designs that depend on non-data-sheet performance of particular devices. There's a very low noise, very low leakage fet popular in charge amplifiers. It has a JEDEC 2N number (which I can't remember off hand), but only the ones from one particular company (in England) actually work in the circuits, and even then, there's some hand selection involved. ___ 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] Simulation
Actually this is a good argument FOR modeling well applied because you can simulate parts that you cannot buy today but that your vendor will ship under the same part number a few years down the road. Try doing that in the lab... I have experienced it so many times it's not even funny. And that includes parts bought against SMD (Standard Military Drawings) which tend to have more complete specs than the commercial parts they target. Another area is simulating the effects or radiations. Quite expensive to do in practice, when it's even practical. On the other hand, if the model does not work like the hardware, don't look for what's wrong with the hardware :) Always get the model to work like the hardware before you make changes. Didier Famous last words: But the prototype worked so well. Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Bob Camp li...@rtty.us Sender: time-nuts-boun...@febo.com Date: Sat, 14 Aug 2010 08:30:29 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Simulation Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. Bob ___ 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] Simulation
(in production yes I agree) In research things are different. You wouldn't mind to make an selection of fets or else to obtain the very top specs of a certain unique instrument design as the real final product are the results you may obtain with that instrument and not at all it's design... So many nice stories about gear that worked only with a certain set of parts way off the manufacturers expressed data... one day I'll drop a few here just for amusement. Luis Cupido ct1dmk. J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John === Bob Camp wrote: Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. there are also designs that depend on non-data-sheet performance of particular devices. There's a very low noise, very low leakage fet popular in charge amplifiers. It has a JEDEC 2N number (which I can't remember off hand), but only the ones from one particular company (in England) actually work in the circuits, and even then, there's some hand selection involved. ___ 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] Simulation
J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John Or, has their back against the wall and can't do it any other way. How is this any different than using trimpots or hand select? For years, folks have hand selected matched pairs of devices, since the circuit requires tighter tolerances than the mfr guarantees. Many, many RF designs have select at test pads to set levels or tuning stubs depending on what the actual gain or impedance properties of the active devices are, or for trimming temperature dependencies. Would you say that the engineer is a fool for not just specifying tighter tolerances.. the tighter tolerances may not be available from the mfr (who has to respond to many customers, most of which will be happy with the standard performance). It's sort of a tradeoff.. do you go to the mfr and say, I need a better grade of part, or do you buy the run-of-the-mill part, and sort them. You might decide to do the latter for competitive reasons, e.g. rather than the mfr producing a better grade of part, and potentially selling it to your competitors too, you keep the secret sauce in house. (Granted you could have the mfr make/select a proprietary part for you.. that's basically changing who does the work, but doesn't change the underlying design) Even manufacturers do this, for instance with speed grades on things like microprocessors. They don't have enough process control to guarantee a particular speed, so they make em all, and then sort them. The other thing is that the selection criteria might not be knowable in a standalone sense. That is, you have to put the part into the circuit and see if it works, rather than measuring some device parameter. I would agree that to a certain extent, this implies that you don't really know how the circuit works, but it might also be that the most cost effective approach is to use empiricism, rather than analysis. ___ 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] Simulation
Simulation has some value in determining things like allowable component tolerances and Worst Case analysis, but those are really production engineering rather than design. As to working at brassboard but not in production, it is prudent to check that your parts are within the production part specs. John === (in production yes I agree) In research things are different. You wouldn't mind to make an selection of fets or else to obtain the very top specs of a certain unique instrument design as the real final product are the results you may obtain with that instrument and not at all it's design... So many nice stories about gear that worked only with a certain set of parts way off the manufacturers expressed data... one day I'll drop a few here just for amusement. Luis Cupido ct1dmk. J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John === Bob Camp wrote: Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. there are also designs that depend on non-data-sheet performance of particular devices. There's a very low noise, very low leakage fet popular in charge amplifiers. It has a JEDEC 2N number (which I can't remember off hand), but only the ones from one particular company (in England) actually work in the circuits, and even then, there's some hand selection involved. ___ 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] Simulation
I think you missinterpret what I meant. Two examples: I've seen programmers who use instructions that are not part of a uP instruction set and are undocumented, just to be clever. If a different brand of chip, or even a different rev., the chip does something completely different. These guys should be strung up by their tender parts. I've also seen transistors used as avalanche switches (basically a failure mode). If a different production run has improved normal mode performance, the avalanche function may vanish. FWIW, -John === J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John Or, has their back against the wall and can't do it any other way. How is this any different than using trimpots or hand select? For years, folks have hand selected matched pairs of devices, since the circuit requires tighter tolerances than the mfr guarantees. Many, many RF designs have select at test pads to set levels or tuning stubs depending on what the actual gain or impedance properties of the active devices are, or for trimming temperature dependencies. Would you say that the engineer is a fool for not just specifying tighter tolerances.. the tighter tolerances may not be available from the mfr (who has to respond to many customers, most of which will be happy with the standard performance). It's sort of a tradeoff.. do you go to the mfr and say, I need a better grade of part, or do you buy the run-of-the-mill part, and sort them. You might decide to do the latter for competitive reasons, e.g. rather than the mfr producing a better grade of part, and potentially selling it to your competitors too, you keep the secret sauce in house. (Granted you could have the mfr make/select a proprietary part for you.. that's basically changing who does the work, but doesn't change the underlying design) Even manufacturers do this, for instance with speed grades on things like microprocessors. They don't have enough process control to guarantee a particular speed, so they make em all, and then sort them. The other thing is that the selection criteria might not be knowable in a standalone sense. That is, you have to put the part into the circuit and see if it works, rather than measuring some device parameter. I would agree that to a certain extent, this implies that you don't really know how the circuit works, but it might also be that the most cost effective approach is to use empiricism, rather than analysis. ___ 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] Simulation
Hi The PDP-8 had so much code that depended on un-documented instructions that they had to include them in later versions of the machine Bob On Aug 14, 2010, at 12:01 PM, J. Forster j...@quik.com wrote: I think you missinterpret what I meant. Two examples: I've seen programmers who use instructions that are not part of a uP instruction set and are undocumented, just to be clever. If a different brand of chip, or even a different rev., the chip does something completely different. These guys should be strung up by their tender parts. I've also seen transistors used as avalanche switches (basically a failure mode). If a different production run has improved normal mode performance, the avalanche function may vanish. FWIW, -John === J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John Or, has their back against the wall and can't do it any other way. How is this any different than using trimpots or hand select? For years, folks have hand selected matched pairs of devices, since the circuit requires tighter tolerances than the mfr guarantees. Many, many RF designs have select at test pads to set levels or tuning stubs depending on what the actual gain or impedance properties of the active devices are, or for trimming temperature dependencies. Would you say that the engineer is a fool for not just specifying tighter tolerances.. the tighter tolerances may not be available from the mfr (who has to respond to many customers, most of which will be happy with the standard performance). It's sort of a tradeoff.. do you go to the mfr and say, I need a better grade of part, or do you buy the run-of-the-mill part, and sort them. You might decide to do the latter for competitive reasons, e.g. rather than the mfr producing a better grade of part, and potentially selling it to your competitors too, you keep the secret sauce in house. (Granted you could have the mfr make/select a proprietary part for you.. that's basically changing who does the work, but doesn't change the underlying design) Even manufacturers do this, for instance with speed grades on things like microprocessors. They don't have enough process control to guarantee a particular speed, so they make em all, and then sort them. The other thing is that the selection criteria might not be knowable in a standalone sense. That is, you have to put the part into the circuit and see if it works, rather than measuring some device parameter. I would agree that to a certain extent, this implies that you don't really know how the circuit works, but it might also be that the most cost effective approach is to use empiricism, rather than analysis. ___ 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] Simulation
DEC code was a nightmare. Any DG Nova line code would run on any machine. -John = Hi The PDP-8 had so much code that depended on un-documented instructions that they had to include them in later versions of the machine Bob On Aug 14, 2010, at 12:01 PM, J. Forster j...@quik.com wrote: I think you missinterpret what I meant. Two examples: I've seen programmers who use instructions that are not part of a uP instruction set and are undocumented, just to be clever. If a different brand of chip, or even a different rev., the chip does something completely different. These guys should be strung up by their tender parts. I've also seen transistors used as avalanche switches (basically a failure mode). If a different production run has improved normal mode performance, the avalanche function may vanish. FWIW, -John === J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John Or, has their back against the wall and can't do it any other way. How is this any different than using trimpots or hand select? For years, folks have hand selected matched pairs of devices, since the circuit requires tighter tolerances than the mfr guarantees. Many, many RF designs have select at test pads to set levels or tuning stubs depending on what the actual gain or impedance properties of the active devices are, or for trimming temperature dependencies. Would you say that the engineer is a fool for not just specifying tighter tolerances.. the tighter tolerances may not be available from the mfr (who has to respond to many customers, most of which will be happy with the standard performance). It's sort of a tradeoff.. do you go to the mfr and say, I need a better grade of part, or do you buy the run-of-the-mill part, and sort them. You might decide to do the latter for competitive reasons, e.g. rather than the mfr producing a better grade of part, and potentially selling it to your competitors too, you keep the secret sauce in house. (Granted you could have the mfr make/select a proprietary part for you.. that's basically changing who does the work, but doesn't change the underlying design) Even manufacturers do this, for instance with speed grades on things like microprocessors. They don't have enough process control to guarantee a particular speed, so they make em all, and then sort them. The other thing is that the selection criteria might not be knowable in a standalone sense. That is, you have to put the part into the circuit and see if it works, rather than measuring some device parameter. I would agree that to a certain extent, this implies that you don't really know how the circuit works, but it might also be that the most cost effective approach is to use empiricism, rather than analysis. ___ 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] Simulation
On 08/14/2010 05:48 PM, J. Forster wrote: Simulation has some value in determining things like allowable component tolerances and Worst Case analysis, but those are really production engineering rather than design. As to working at brassboard but not in production, it is prudent to check that your parts are within the production part specs. Simulation as such is a very useful tool. Propper use may save time, misuse will cost you big-time. It does not replace breadboarding and design verification, but may speed up design and what if? on failure mode testing. I've often found that proposing a solution and have a quick simulation has helped in convincing on certain design ideas. In particular some designer make things more complex than they need to be... but a quick simulation gets them on the right track. :) 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] Simulation
On 08/14/2010 06:15 PM, J. Forster wrote: DEC code was a nightmare. Any DG Nova line code would run on any machine. This is how we have learned what is a bad idea... and it is now documented in the guidelines. Use of the top 8 bits in pointers caused headaches for the 68k machines when they needed more than 16 MB of addressing. Amongst other things. The undocumented features of the 6502 is now being maintained in modernized versions... maybe a better choice in design could be made. 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] Simulation
Hello, I've read at least two similar stories in Troubleshooting Analog Circuits by Bob Pease. One is that it seems that some time ago, National Semiconductor started shipping LF411s marked as LF351s as an improvement... and as Bob says, most of the customers probably were happy with that (I think that most of them probably never noticed the change), but the gain on the trim circuit was reversed (in the LF351, if you turn the trim pot in one way, Vos increases - in the LF411, turning it in the same way makes Vos to decrease), and this probably would have made some people not so happy with the improvement :) Another story is about 2N3771 transistor, initially a single-diffussed part, but later an epitaxial base part - with a lot more gain bandwidth product. But since the 'new' 2N3771 meets and exceeds original 2N3771 specs, the same part number was used - but the part is quite different (and published specs continues being the JEDEC ones). So you can imagine that in some applications it would be quite a lot of difference if you breadboard with the older, and during the manufacturing phase you (probably without knowing it) switch to the new part. I suffered some time ago a change in a small DSP from Freescale. It is a 3.3V part with 5V tolerant I/O, and I assumed (not sure if this was in the datasheet or not) that reset pin was also 5V tolerant. Prototypes worked, and production worked, but after 2-3 years of production, and from some DSP production date code, we experienced a problem with the part reset - the part did no longer liked the 5V level at the reset pin. I asked Freescale about any change, but never got any response. I periodically receive PCNs (product change notifications) from EBV Elektronik, which is a quite big european semiconductor distributor, whenever some product that I'm purchasing or have purchased in the past suffers some manufacturing change (manufacturing moved to other plant, process change, case materials change, etc...), like for example this one: http://www.ebv.com/fileadmin/templates/scripts/pcn/data/200907002f__1248209503.pdf But I suppose that not all manufacturers are so kind to let the customers know in advance these kind of things :) Best regards, Javier El 14/08/2010 14:30, Bob Camp escribió: Hi Simply a few stories I thought I would share. Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now much better ( now 3x old parts ). Odd they never mentioned that to people who work for the same company. Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around. Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit. We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the old version ones. Bob ___ 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. -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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] Simulation
On 08/14/2010 06:39 PM, Javier Herrero wrote: Hello, I've read at least two similar stories in Troubleshooting Analog Circuits by Bob Pease. One is that it seems that some time ago, National Semiconductor started shipping LF411s marked as LF351s as an improvement... and as Bob says, most of the customers probably were happy with that (I think that most of them probably never noticed the change), but the gain on the trim circuit was reversed (in the LF351, if you turn the trim pot in one way, Vos increases - in the LF411, turning it in the same way makes Vos to decrease), and this probably would have made some people not so happy with the improvement :) Another story is about 2N3771 transistor, initially a single-diffussed part, but later an epitaxial base part - with a lot more gain bandwidth product. But since the 'new' 2N3771 meets and exceeds original 2N3771 specs, the same part number was used - but the part is quite different (and published specs continues being the JEDEC ones). So you can imagine that in some applications it would be quite a lot of difference if you breadboard with the older, and during the manufacturing phase you (probably without knowing it) switch to the new part. One side-effect is that you run into possibilities of oscillation. This have happend and was the cause of a GPS outage in a US Harbour a few years back. What was a wise design became an enemy due to a subtle change in part. Don't recall if the part was replaced by an equivalent or same part-number, but the new version didn't work as expected during all conditions... 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] Simulation
One side-effect is that you run into possibilities of oscillation. This have happend and was the cause of a GPS outage in a US Harbour a few years back. What was a wise design became an enemy due to a subtle change in part. Don't recall if the part was replaced by an equivalent or same part-number, but the new version didn't work as expected during all conditions... Yes, one of the most probable problems. I've read the story about the GPS outage in that harbour, as I remember it was caused by a failure in one TV antenna amplifier on a boat - but I don't remember if it was an isolated case due to a failure (or to a bad repair replacing the part with a similar one), or was a more 'endemic' problem :) Regards, Javier -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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] Simulation
I think this is pretty common with transistors. A company is making a particular part, then a new, better part comes along that exceeds the spec of an existing part. So they start putting the new die into the old package as well as making the new part. Fewer dice to make likely means cheaper and less hassels. And they don't tell anyone. Win-win, except the new part has a much higher Ft for example and formerly stable circuits now oscillate badly. Tilt! -John = Hello, [snip] Another story is about 2N3771 transistor, initially a single-diffussed part, but later an epitaxial base part - with a lot more gain bandwidth product. But since the 'new' 2N3771 meets and exceeds original 2N3771 specs, the same part number was used - but the part is quite different (and published specs continues being the JEDEC ones). So you can imagine that in some applications it would be quite a lot of difference if you breadboard with the older, and during the manufacturing phase you (probably without knowing it) switch to the new part. [snip] Best 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] Simulation
I think it was a one-off failure: http://www.gpsworld.com/gnss-system/signal-processing/the-hunt-rfi-776 -John === One side-effect is that you run into possibilities of oscillation. This have happend and was the cause of a GPS outage in a US Harbour a few years back. What was a wise design became an enemy due to a subtle change in part. Don't recall if the part was replaced by an equivalent or same part-number, but the new version didn't work as expected during all conditions... Yes, one of the most probable problems. I've read the story about the GPS outage in that harbour, as I remember it was caused by a failure in one TV antenna amplifier on a boat - but I don't remember if it was an isolated case due to a failure (or to a bad repair replacing the part with a similar one), or was a more 'endemic' problem :) Regards, Javier -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Simulation
Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. Or, as Javier said: I periodically receive PCNs (product change notifications) from EBV Elektronik, which is a quite big european semiconductor distributor, So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. -- 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] Simulation
On 08/14/2010 07:10 PM, J. Forster wrote: I think it was a one-off failure: http://www.gpsworld.com/gnss-system/signal-processing/the-hunt-rfi-776 This is the incident I described, but notice that there where three sources, two of which was different antennas with the same amplifier... both instances had the problem. I have seen another report from this incident where they pointed out the differences in component for the same design. A very benign subtle difference... Doesn't seem to find it right now. 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] Simulation
El 14/08/2010 19:17, Hal Murray escribió: So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. Yes. I'm not a high volume customer, only mid-to-low :) But I receive the PCNs even for components that I've only purchased one 50pcs bar for a special project. But I'm not sure if all manufacturers are the same. This example from NXP is very very detailed, in other cases there is only a note that production has changed from one factory to another. Regards, Javier -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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] Simulation
Hi Not so much. Mil grade just makes sure they qualify a change. At the time we had the issues the volume on the transistors was quite high. The cost os screening was still prohibitive. They write the specs with very few limits for a reason Bob On Aug 14, 2010, at 1:17 PM, Hal Murray hmur...@megapathdsl.net wrote: Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. Or, as Javier said: I periodically receive PCNs (product change notifications) from EBV Elektronik, which is a quite big european semiconductor distributor, So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. -- 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] Simulation
Hi I seem to get weekly notices about a resin changing or a new date code format. Silicon changes don't seem to be on the same system. That's still better than it was 30 years back. Bob On Aug 14, 2010, at 1:38 PM, Javier Herrero jherr...@hvsistemas.es wrote: El 14/08/2010 19:17, Hal Murray escribió: So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. Yes. I'm not a high volume customer, only mid-to-low :) But I receive the PCNs even for components that I've only purchased one 50pcs bar for a special project. But I'm not sure if all manufacturers are the same. This example from NXP is very very detailed, in other cases there is only a note that production has changed from one factory to another. Regards, Javier -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Simulation
I sometimes get some PCNs about process changes on silicon (new process or new masks). I suppose that depends on manufacturers :) Regards, Javier El 14/08/2010 19:49, Bob Camp escribió: Hi I seem to get weekly notices about a resin changing or a new date code format. Silicon changes don't seem to be on the same system. That's still better than it was 30 years back. Bob On Aug 14, 2010, at 1:38 PM, Javier Herrerojherr...@hvsistemas.es wrote: El 14/08/2010 19:17, Hal Murray escribió: So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. Yes. I'm not a high volume customer, only mid-to-low :) But I receive the PCNs even for components that I've only purchased one 50pcs bar for a special project. But I'm not sure if all manufacturers are the same. This example from NXP is very very detailed, in other cases there is only a note that production has changed from one factory to another. Regards, Javier -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Javier HerreroEMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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] Simulation
Mil specs cover a number of things that are not always in the commercial specs, but not always, and mil spec parts are going the way of the dodo. Nobody wants to make them, except the local garage shop which does not mind selling you $0.02 parts for $60 (quite common) and the worst is that these parts are often made in very small runs from the old masks, or they are custom packaged dies bought from commercial sources and screened to meet the requirements and end up having very poor reliability because the small runs do not allow the quality of commercial parts made in the gazillion. Quite a paradox!!! In my 30 years experience designing military and space hardware, I now believe the commercial grade plastic parts you get from Digikey are quite a bit better than the expensive mil spec ones in the hermetic packages, even when rated 0-70C and when used in a humid environment. Of course, if you have to have hermetic parts to satisfy an explicit customer requirement, that's another story, even though I have been fairly successful at obtaining waivers from customers in that regard. Didier Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Hal Murray hmur...@megapathdsl.net Sender: time-nuts-boun...@febo.com Date: Sat, 14 Aug 2010 10:17:32 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Simulation Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. Or, as Javier said: I periodically receive PCNs (product change notifications) from EBV Elektronik, which is a quite big european semiconductor distributor, So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. -- 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] Simulation
When I was building spacecraft payloads for the USAF, there was a lot of resistance to using commercial parts. If something failed, you had to right back to square one with the acceptance tests, and that took months. Often we just used stuff from the Apollo QPL. -John = Mil specs cover a number of things that are not always in the commercial specs, but not always, and mil spec parts are going the way of the dodo. Nobody wants to make them, except the local garage shop which does not mind selling you $0.02 parts for $60 (quite common) and the worst is that these parts are often made in very small runs from the old masks, or they are custom packaged dies bought from commercial sources and screened to meet the requirements and end up having very poor reliability because the small runs do not allow the quality of commercial parts made in the gazillion. Quite a paradox!!! In my 30 years experience designing military and space hardware, I now believe the commercial grade plastic parts you get from Digikey are quite a bit better than the expensive mil spec ones in the hermetic packages, even when rated 0-70C and when used in a humid environment. Of course, if you have to have hermetic parts to satisfy an explicit customer requirement, that's another story, even though I have been fairly successful at obtaining waivers from customers in that regard. Didier Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Hal Murray hmur...@megapathdsl.net Sender: time-nuts-boun...@febo.com Date: Sat, 14 Aug 2010 10:17:32 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Simulation Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. Or, as Javier said: I periodically receive PCNs (product change notifications) from EBV Elektronik, which is a quite big european semiconductor distributor, So maybe it doesn't take a high volume, you just have to get plugged into the right paperwork flow and then read all the fine print to see if the change is interesting. -- 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. ___ 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] Simulation
On 8/14/2010 10:08 AM, J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John This is, easily said, a wonderful goal, and absolute fantasy. It's optimistic at best to expect someone to anticipate all contingencies. It's certainly good practice to specific critical parameters, but it's rarely makes economic sense to specify every possible detail. As to relying upon unspecified parameters, most datasheets are woefully incomplete. If you are going to use any significant number parts, it's unlikely that you'll be able to get everything specified, much less get compliance commitments for each parameter. Few vendors are willing to do the testing required to guarantee a substantial number of parameters, and the simple reason is no one is willing to pay for it. I've spent quite a bit of time dealing with maintenance of military systems that would be long obsolete in any other business. After obsolescence, the number one problem was parts that meet all published specs, but had changed performance so much (for better or worse) that they no longer functioned in the application. A common problem is Ft or gain, but leakages are often orders of magnitude different. As often as not, they were much worse. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Simulation
On 8/14/2010 12:10 PM, J. Forster wrote: I think it was a one-off failure: http://www.gpsworld.com/gnss-system/signal-processing/the-hunt-rfi-776 -John I wish it were a one off. I and friends at cell ops chase these things all of the time in the cellular and public safety bands. This one just happened to be in a location that covered a wide area in a densely populated area. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Simulation
I can't recall hearing of other wide-area jamming of GPS, but they may not have reached the media. Certainly, that incident alone demonstrates the vulnerability of GPS and argues against the shutdown of LORAN. -Jo0hn === On 8/14/2010 12:10 PM, J. Forster wrote: I think it was a one-off failure: http://www.gpsworld.com/gnss-system/signal-processing/the-hunt-rfi-776 -John I wish it were a one off. I and friends at cell ops chase these things all of the time in the cellular and public safety bands. This one just happened to be in a location that covered a wide area in a densely populated area. ___ 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] Simulation
On 8/14/2010 10:08 AM, J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John This is, easily said, a wonderful goal, and absolute fantasy. It's optimistic at best to expect someone to anticipate all contingencies. It's certainly good practice to specific critical parameters, but it's rarely makes economic sense to specify every possible detail. OK, important uncontrolled parameters. For example, I'd consider things like hFE; VCEsat; VCBO, fT and others important, but not the package capacitance in a low frequency transistor. There are clearly unimportant parameters and essentially irrelevant ones. That's where experience and good judgement comes in. If your circuit is not stable with a high fT part, that needs to be tested or the design fixed. As to relying upon unspecified parameters, most datasheets are woefully incomplete. If you are going to use any significant number parts, it's unlikely that you'll be able to get everything specified, much less get compliance commitments for each parameter. Few vendors are willing to do the testing required to guarantee a substantial number of parameters, and the simple reason is no one is willing to pay for it. If your design is that critical, you may have to do incoming inspectrion/selection or send the parts to a company that does. I've spent quite a bit of time dealing with maintenance of military systems that would be long obsolete in any other business. After obsolescence, the number one problem was parts that meet all published specs, but had changed performance so much (for better or worse) that they no longer functioned in the application. A common problem is Ft or gain, but leakages are often orders of magnitude different. As often as not, they were much worse. Certainly, old Ge power transistors have ICBO issues. -John === -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Simulation
Hi It's a very rare thing to see jelly bean parts screened for RF parameters. Much more common to catch and fix an issue at the board level. Pretty rare to see discrete RF anymore anyway. Bob On Aug 14, 2010, at 3:56 PM, J. Forster j...@quik.com wrote: On 8/14/2010 10:08 AM, J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John This is, easily said, a wonderful goal, and absolute fantasy. It's optimistic at best to expect someone to anticipate all contingencies. It's certainly good practice to specific critical parameters, but it's rarely makes economic sense to specify every possible detail. OK, important uncontrolled parameters. For example, I'd consider things like hFE; VCEsat; VCBO, fT and others important, but not the package capacitance in a low frequency transistor. There are clearly unimportant parameters and essentially irrelevant ones. That's where experience and good judgement comes in. If your circuit is not stable with a high fT part, that needs to be tested or the design fixed. As to relying upon unspecified parameters, most datasheets are woefully incomplete. If you are going to use any significant number parts, it's unlikely that you'll be able to get everything specified, much less get compliance commitments for each parameter. Few vendors are willing to do the testing required to guarantee a substantial number of parameters, and the simple reason is no one is willing to pay for it. If your design is that critical, you may have to do incoming inspectrion/selection or send the parts to a company that does. I've spent quite a bit of time dealing with maintenance of military systems that would be long obsolete in any other business. After obsolescence, the number one problem was parts that meet all published specs, but had changed performance so much (for better or worse) that they no longer functioned in the application. A common problem is Ft or gain, but leakages are often orders of magnitude different. As often as not, they were much worse. Certainly, old Ge power transistors have ICBO issues. -John === -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Simulation
I've seen audio range power amps that will oscillate on a part of a cycle because an output device with a higher fT was installed. Older vintage parts with the same type JEDEC number never did that. -John Hi It's a very rare thing to see jelly bean parts screened for RF parameters. Much more common to catch and fix an issue at the board level. Pretty rare to see discrete RF anymore anyway. Bob On Aug 14, 2010, at 3:56 PM, J. Forster j...@quik.com wrote: On 8/14/2010 10:08 AM, J. Forster wrote: FWIW, IMO any engineer who uses undocumented or uncontrolled parameters or instructions in a production design is a fool. If you are that silly, you must fully specify the selection criteria. -John This is, easily said, a wonderful goal, and absolute fantasy. It's optimistic at best to expect someone to anticipate all contingencies. It's certainly good practice to specific critical parameters, but it's rarely makes economic sense to specify every possible detail. OK, important uncontrolled parameters. For example, I'd consider things like hFE; VCEsat; VCBO, fT and others important, but not the package capacitance in a low frequency transistor. There are clearly unimportant parameters and essentially irrelevant ones. That's where experience and good judgement comes in. If your circuit is not stable with a high fT part, that needs to be tested or the design fixed. As to relying upon unspecified parameters, most datasheets are woefully incomplete. If you are going to use any significant number parts, it's unlikely that you'll be able to get everything specified, much less get compliance commitments for each parameter. Few vendors are willing to do the testing required to guarantee a substantial number of parameters, and the simple reason is no one is willing to pay for it. If your design is that critical, you may have to do incoming inspectrion/selection or send the parts to a company that does. I've spent quite a bit of time dealing with maintenance of military systems that would be long obsolete in any other business. After obsolescence, the number one problem was parts that meet all published specs, but had changed performance so much (for better or worse) that they no longer functioned in the application. A common problem is Ft or gain, but leakages are often orders of magnitude different. As often as not, they were much worse. Certainly, old Ge power transistors have ICBO issues. -John === -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ 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] Simulation
Hal Murray wrote: Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. just so.. In the space business, we call it traceability to sand... you haven't lived til someone has a failed 2n, somwhere on some piece of critical hardware, and they issue a GIDEP alert, and then the mission assurance folks call you up and ask, you don't by any chance have 2N's in your flight hardware do you?.. then there's the whole manufacturer and date code hunt.. Looking through the build documentation to find out. (or worse yet, if you had decided for some reason to use the prototype, which you didn't keep such good records on, but which you have photos of, and trying to read the date codes off the assembled item with a magnifying glass) ___ 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] Simulation
On Apollo they had file cabinets full of drawers for IBM punch cards, except each had a microfilm insert. They could trace a single #6-32 screw back to the mine the iron ore came from. -John = Hal Murray wrote: Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. just so.. In the space business, we call it traceability to sand... you haven't lived til someone has a failed 2n, somwhere on some piece of critical hardware, and they issue a GIDEP alert, and then the mission assurance folks call you up and ask, you don't by any chance have 2N's in your flight hardware do you?.. then there's the whole manufacturer and date code hunt.. Looking through the build documentation to find out. (or worse yet, if you had decided for some reason to use the prototype, which you didn't keep such good records on, but which you have photos of, and trying to read the date codes off the assembled item with a magnifying glass) ___ 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] Simulation
Once I had a batch of JANTX 2NA (with all the paperwork) that were PNPs. They actually were marked JANTX 2NA. This was for a mil job in the 80's. We did not fool around with the mil specs back then. I was a young engineer then and not all that involved in the process, so I was kept somewhat out of the process that followed. I wish I has seen QA and purchasing explain that one :) Didier Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: jimlux jim...@earthlink.net Sender: time-nuts-boun...@febo.com Date: Sat, 14 Aug 2010 14:42:39 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Simulation Hal Murray wrote: Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. just so.. In the space business, we call it traceability to sand... you haven't lived til someone has a failed 2n, somwhere on some piece of critical hardware, and they issue a GIDEP alert, and then the mission assurance folks call you up and ask, you don't by any chance have 2N's in your flight hardware do you?.. then there's the whole manufacturer and date code hunt.. Looking through the build documentation to find out. (or worse yet, if you had decided for some reason to use the prototype, which you didn't keep such good records on, but which you have photos of, and trying to read the date codes off the assembled item with a magnifying glass) ___ 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] Simulation
Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Didier Juges Sent: Saturday, August 14, 2010 6:18 PM To: Time-Nuts Subject: Re: [time-nuts] Simulation Once I had a batch of JANTX 2NA (with all the paperwork) that were PNPs. They actually were marked JANTX 2NA. This was for a mil job in the 80's. We did not fool around with the mil specs back then. I was a young engineer then and not all that involved in the process, so I was kept somewhat out of the process that followed. I wish I has seen QA and purchasing explain that one :) Didier ___ 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] Simulation
In a message dated 14/08/2010 23:39:20 GMT Daylight Time, mfe...@eozinc.com writes: Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike -- Wasn't that exactly the point that was being made?:-) regards Nigel GM8PZR ___ 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] Simulation
Surely all this is a case of an engineer being able to read..specifications :-)) Manufactures specify to sell parts, most of the important parameter are minimum values, and the range is as wide as it can be. If you want a parameter bracketed then you must specify that when buying and pay the premium or take the expense of testing incomming batches for sensitive parameters. I used to give lectures to new engineers on reading specifications .and what Absolute maximum actually means. Clever engineers also love using operations that rely on unspecified parameters. For example using a stock switching diode as a spike quencher in a relay driver. The usually work (but not always!) but are generally not specified for that service. Spice parameters are probably a few typical samples of even the one I happened to choose to measure!! I had a case of some +/-12v transistor logic which made it was into a big telecoms project. the prototypes worked fine. By the time of bulk manufacture the supplier of the the main transistor had had several cost improvement stages. The result was the kit was unreliable. The problem was that first the base junction were swung to -12v by the 0 logic state and second from a transistor with a fairly simple round dot geometry emitter, the device had been replaced by an interdigital high ft chip (it still met the basic greater than specs.) The interdigital device suffered severe loss of gain after a period of avalanching at several millamps (I think it also suffered electromigration) much more than the circular geometry transistors. I think this was due to the increased emitter periphery length. It was solved by placing a simple diode in the emitter leg, or a clamp on the base. The engineer had not read, or not understood the meaning of the Vebmax = 5v parameter, and his prototype had worked. The production side were not very happy but eventually were forced to junk thousands of 8inch square pcbs and do a re-layout. This was in the days before computer simulation !! It might have helped! Alan G3NYK - Original Message - From: jimlux jim...@earthlink.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, August 14, 2010 10:42 PM Subject: Re: [time-nuts] Simulation Hal Murray wrote: Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. just so.. In the space business, we call it traceability to sand... you haven't lived til someone has a failed 2n, somwhere on some piece of critical hardware, and they issue a GIDEP alert, and then the mission assurance folks call you up and ask, you don't by any chance have 2N's in your flight hardware do you?.. then there's the whole manufacturer and date code hunt.. Looking through the build documentation to find out. (or worse yet, if you had decided for some reason to use the prototype, which you didn't keep such good records on, but which you have photos of, and trying to read the date codes off the assembled item with a magnifying glass) ___ 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] Simulation
Hi Simulation might or might not have helped. 1) Was Vbe breakdown even included in the Spice model 2) If so did it ring bells (rare) or did it just clip without error ( common ) 3) Would the same designer who didn't understand it in the first place have seen it clipping at -5 and concluded looks to be in spec at -5 4) Would any of it be reviewed in light of the new transistor or was the guy on another project by then My favorite in the absolute max Vbe category is the typical class C RF amp. Look at the spec, check a few thousand working boards. Scratch head and move on. Lots of reverse bias on the base and they run forever. Bob On Aug 14, 2010, at 7:47 PM, Alan Melia alan.me...@btinternet.com wrote: Surely all this is a case of an engineer being able to read..specifications :-)) Manufactures specify to sell parts, most of the important parameter are minimum values, and the range is as wide as it can be. If you want a parameter bracketed then you must specify that when buying and pay the premium or take the expense of testing incomming batches for sensitive parameters. I used to give lectures to new engineers on reading specifications .and what Absolute maximum actually means. Clever engineers also love using operations that rely on unspecified parameters. For example using a stock switching diode as a spike quencher in a relay driver. The usually work (but not always!) but are generally not specified for that service. Spice parameters are probably a few typical samples of even the one I happened to choose to measure!! I had a case of some +/-12v transistor logic which made it was into a big telecoms project. the prototypes worked fine. By the time of bulk manufacture the supplier of the the main transistor had had several cost improvement stages. The result was the kit was unreliable. The problem was that first the base junction were swung to -12v by the 0 logic state and second from a transistor with a fairly simple round dot geometry emitter, the device had been replaced by an interdigital high ft chip (it still met the basic greater than specs.) The interdigital device suffered severe loss of gain after a period of avalanching at several millamps (I think it also suffered electromigration) much more than the circular geometry transistors. I think this was due to the increased emitter periphery length. It was solved by placing a simple diode in the emitter leg, or a clamp on the base. The engineer had not read, or not understood the meaning of the Vebmax = 5v parameter, and his prototype had worked. The production side were not very happy but eventually were forced to junk thousands of 8inch square pcbs and do a re-layout. This was in the days before computer simulation !! It might have helped! Alan G3NYK - Original Message - From: jimlux jim...@earthlink.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, August 14, 2010 10:42 PM Subject: Re: [time-nuts] Simulation Hal Murray wrote: Line got moved to other side of big ocean. Process got tweaked beta is now 4x what it was. I'm pretty sure that military grade parts have paperwork and processes to cover that case. I expect it costs a lot. I think the same sort of service is available to high volume customers at a less than military price. just so.. In the space business, we call it traceability to sand... you haven't lived til someone has a failed 2n, somwhere on some piece of critical hardware, and they issue a GIDEP alert, and then the mission assurance folks call you up and ask, you don't by any chance have 2N's in your flight hardware do you?.. then there's the whole manufacturer and date code hunt.. Looking through the build documentation to find out. (or worse yet, if you had decided for some reason to use the prototype, which you didn't keep such good records on, but which you have photos of, and trying to read the date codes off the assembled item with a magnifying glass) ___ 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] Simulation
Yes, I guess it was. I have been in the military business since 1967, and, certainly seen my share. Besides all of the screw ups, there was one that really took the cake. I once worked for a company that had to build a radio that was strictly build-to-print. The original drawing had a mil-spec yellow band resistor of value X in the front end. Well, with that resistor the NF could not be met. They could meet it with a value Y. Pleading with the government reps made no difference. Finally, the head of the company QA department wrote a letter to AB and actually asked them to provide resistors with value Y, but, color code them with the value X. Everyone signed off on it, and, everything was fine. I still have a copy of the letter someplace. I just got back from Fort Bragg where I was involved in certifying a system at Ka band. The antenna is a 30 footer and had only a 10 degree elevation look angle to see the bird needed. Well, guess what? There are three 30 foot dishes in the system, the other two being Ku, and this antenna was between them looking right through one of the Ku antennas. Really messed with the patterns. Now, based on my input they are changing the feed assembly and all of the RF between the two antennas to prevent the blockage. It will take a month. I am sure I will be there again. A few simple examples of hundreds. - Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gandal...@aol.com Sent: Saturday, August 14, 2010 6:52 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Simulation In a message dated 14/08/2010 23:39:20 GMT Daylight Time, mfe...@eozinc.com writes: Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike -- Wasn't that exactly the point that was being made?:-) regards Nigel GM8PZR ___ 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] Simulation
?? The yellow banded R means established reliability. I see no reason why the NF should be any different then one w/o the yellow band. They are the same part, only one is tested more. Not white band perchance? -John === Yes, I guess it was. I have been in the military business since 1967, and, certainly seen my share. Besides all of the screw ups, there was one that really took the cake. I once worked for a company that had to build a radio that was strictly build-to-print. The original drawing had a mil-spec yellow band resistor of value X in the front end. Well, with that resistor the NF could not be met. They could meet it with a value Y. Pleading with the government reps made no difference. Finally, the head of the company QA department wrote a letter to AB and actually asked them to provide resistors with value Y, but, color code them with the value X. Everyone signed off on it, and, everything was fine. I still have a copy of the letter someplace. I just got back from Fort Bragg where I was involved in certifying a system at Ka band. The antenna is a 30 footer and had only a 10 degree elevation look angle to see the bird needed. Well, guess what? There are three 30 foot dishes in the system, the other two being Ku, and this antenna was between them looking right through one of the Ku antennas. Really messed with the patterns. Now, based on my input they are changing the feed assembly and all of the RF between the two antennas to prevent the blockage. It will take a month. I am sure I will be there again. A few simple examples of hundreds. - Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gandal...@aol.com Sent: Saturday, August 14, 2010 6:52 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Simulation In a message dated 14/08/2010 23:39:20 GMT Daylight Time, mfe...@eozinc.com writes: Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike -- Wasn't that exactly the point that was being made?:-) regards Nigel GM8PZR ___ 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] Simulation
I only mentioned the yellow band because of reliability. Seems like the original resistor was 220 ohms and the one that actually met the required NF was 330 (or the other way around). So, it was not the yellow band that had to be changed. - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Saturday, August 14, 2010 9:43 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Simulation ?? The yellow banded R means established reliability. I see no reason why the NF should be any different then one w/o the yellow band. They are the same part, only one is tested more. Not white band perchance? -John === Yes, I guess it was. I have been in the military business since 1967, and, certainly seen my share. Besides all of the screw ups, there was one that really took the cake. I once worked for a company that had to build a radio that was strictly build-to-print. The original drawing had a mil-spec yellow band resistor of value X in the front end. Well, with that resistor the NF could not be met. They could meet it with a value Y. Pleading with the government reps made no difference. Finally, the head of the company QA department wrote a letter to AB and actually asked them to provide resistors with value Y, but, color code them with the value X. Everyone signed off on it, and, everything was fine. I still have a copy of the letter someplace. I just got back from Fort Bragg where I was involved in certifying a system at Ka band. The antenna is a 30 footer and had only a 10 degree elevation look angle to see the bird needed. Well, guess what? There are three 30 foot dishes in the system, the other two being Ku, and this antenna was between them looking right through one of the Ku antennas. Really messed with the patterns. Now, based on my input they are changing the feed assembly and all of the RF between the two antennas to prevent the blockage. It will take a month. I am sure I will be there again. A few simple examples of hundreds. - Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gandal...@aol.com Sent: Saturday, August 14, 2010 6:52 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Simulation In a message dated 14/08/2010 23:39:20 GMT Daylight Time, mfe...@eozinc.com writes: Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike -- Wasn't that exactly the point that was being made?:-) regards Nigel GM8PZR ___ 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] Simulation
Hi I think it was the value that changed. Somebody typo'd 10k at 10 ohms Bob On Aug 14, 2010, at 9:42 PM, J. Forster j...@quik.com wrote: ?? The yellow banded R means established reliability. I see no reason why the NF should be any different then one w/o the yellow band. They are the same part, only one is tested more. Not white band perchance? -John === Yes, I guess it was. I have been in the military business since 1967, and, certainly seen my share. Besides all of the screw ups, there was one that really took the cake. I once worked for a company that had to build a radio that was strictly build-to-print. The original drawing had a mil-spec yellow band resistor of value X in the front end. Well, with that resistor the NF could not be met. They could meet it with a value Y. Pleading with the government reps made no difference. Finally, the head of the company QA department wrote a letter to AB and actually asked them to provide resistors with value Y, but, color code them with the value X. Everyone signed off on it, and, everything was fine. I still have a copy of the letter someplace. I just got back from Fort Bragg where I was involved in certifying a system at Ka band. The antenna is a 30 footer and had only a 10 degree elevation look angle to see the bird needed. Well, guess what? There are three 30 foot dishes in the system, the other two being Ku, and this antenna was between them looking right through one of the Ku antennas. Really messed with the patterns. Now, based on my input they are changing the feed assembly and all of the RF between the two antennas to prevent the blockage. It will take a month. I am sure I will be there again. A few simple examples of hundreds. - Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gandal...@aol.com Sent: Saturday, August 14, 2010 6:52 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Simulation In a message dated 14/08/2010 23:39:20 GMT Daylight Time, mfe...@eozinc.com writes: Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike -- Wasn't that exactly the point that was being made?:-) regards Nigel GM8PZR ___ 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] Simulation
Somebody read the resistor code backwards then? Easy enough if you don't know what you're doing w/ Established Reliability parts. -John = I only mentioned the yellow band because of reliability. Seems like the original resistor was 220 ohms and the one that actually met the required NF was 330 (or the other way around). So, it was not the yellow band that had to be changed. - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: Saturday, August 14, 2010 9:43 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Simulation ?? The yellow banded R means established reliability. I see no reason why the NF should be any different then one w/o the yellow band. They are the same part, only one is tested more. Not white band perchance? -John === Yes, I guess it was. I have been in the military business since 1967, and, certainly seen my share. Besides all of the screw ups, there was one that really took the cake. I once worked for a company that had to build a radio that was strictly build-to-print. The original drawing had a mil-spec yellow band resistor of value X in the front end. Well, with that resistor the NF could not be met. They could meet it with a value Y. Pleading with the government reps made no difference. Finally, the head of the company QA department wrote a letter to AB and actually asked them to provide resistors with value Y, but, color code them with the value X. Everyone signed off on it, and, everything was fine. I still have a copy of the letter someplace. I just got back from Fort Bragg where I was involved in certifying a system at Ka band. The antenna is a 30 footer and had only a 10 degree elevation look angle to see the bird needed. Well, guess what? There are three 30 foot dishes in the system, the other two being Ku, and this antenna was between them looking right through one of the Ku antennas. Really messed with the patterns. Now, based on my input they are changing the feed assembly and all of the RF between the two antennas to prevent the blockage. It will take a month. I am sure I will be there again. A few simple examples of hundreds. - Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gandal...@aol.com Sent: Saturday, August 14, 2010 6:52 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Simulation In a message dated 14/08/2010 23:39:20 GMT Daylight Time, mfe...@eozinc.com writes: Not that it really matters for this thread, but, the 2NA was one of the most common NPNs and not PNPs. As I recall, the 2N2907A was its PNP complement. - regards - Mike -- Wasn't that exactly the point that was being made?:-) regards Nigel GM8PZR ___ 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] Simulation tools for oscillators
Ansoft Designer is intended for RF/Microwave applications. I don't know how well it simulates an oscillator as most often I have heard of it used for amplifiers and filters. Anyway, there is a student version that is free so it is worth a look. http://www.ansoft.com/products/hf/ansoft_designer/ Mike WB8GXB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tim Shoppa Sent: Tuesday, December 26, 2006 11:24 AM To: time-nuts@febo.com Subject: [time-nuts] Simulation tools for oscillators Are there any useful, free or near-free tools for simulating high-performance oscillators? I'm thinking particularly about making at least a little bit quantatitive statments about phase noise through simulation. SPICE will simulate an oscillator starting up, doesn't do a particularly good job when the nonlinearities of a simple oscillator kick in to limit the amplitude but most of the active device models can be tweaked to mimic the real world near saturation. If the active devices never go into saturation but there's an actual AGC loop then things can be done somewhat realistically without tweaking. But I have no idea how to properly model phase noise in even the most cartoon-like way with SPICE. Setting the time step to something ridiculously small and then FFTing to the frequency domain is almost completely hopeless due to all the numerical noise. SPICE old-timers will laugh at me because I even tried to simulate an oscillator in it, I'm sure :-). Hey, I actually started on a 11/780 with 50 users too! What do the pros use? I know there are goals (maximize power, minimize noise, at the same time minimize heating) and SPICE can vaguely help with them but common sense and cut-and-try seem to be the best tools I know of! Tim. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
