Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
Jim, This is an interesting product, thank for the link! Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Jim Lux jim...@earthlink.net Sender: time-nuts-boun...@febo.com Date: Tue, 04 Oct 2011 08:40:55 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] [Solved] Looking for multiple PPS timestamp logging On 10/4/11 8:03 AM, Kevin Rosenberg wrote: So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendipitous time. DATAQ http://www.dataq.com/products/startkit/di145.html $29, 4 channel 10 bit ADC with USB interface You'll need to cobble up a sensor, of course, and I don't know if the resolution of the di145 is good enough (20mV/LSB as I recall) for a LM335 (10mV/Kelvin?). One thing you get with cheap is a +/- 10V full scale range. A thermistor and resistor into the DATAQ might work better. Maxim/Dallas One-Wire devices are another possibility There's tons of PIC code out there to interface to them. The sensors are cheap (few bucks, depending on whether you buy raw device, or you get one potted with a cable) Sparkfun.com has them, among other places. There's also a whole raft of USB temperature loggers out there from Onset (HOBO) or DataQ or a variety of other companies. They tend to run in the $80 range (if someone knows about a battery powered temperature logger in the under $25 range, I'd love to hear about it) And, of course, a DMM with a RS-232 interface is another possibility ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
On Oct 4, 2011, at 11:42 AM, Mark Sims wrote: Use an LM34 sensor, not the LM35. It has twice the resolution per volt since it outputs in degrees F, not degrees C. That's a good idea. That's one issue that I have with a 10-bit ADC common to many MCUs, is the low voltage of 0.20 to 0.28 mV in the office. Better yet, use the DS1620 (old revision) that is used on the Tbolt. It has a digital interface. It will give you around 0.01C res without any ADC conversion noise, etc. That's a good idea. In fact, I saw that I have some DS1631 samples on the shelf. I like that idea as that can be bit-banged by a simple, small MCU on same board as the XO. Thanks for the thoughts, Mark! Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
Hi Chris, select is a great idea, but I think I'll be using cygwin which doesn't appear to have an emulation of select on Windows. Kevin On Oct 4, 2011, at 10:23 AM, Chris Albertson wrote: On Tue, Oct 4, 2011 at 3:36 AM, Hal Murray hmur...@megapathdsl.net wrote: The temperature swings won't be large, just the usual diuneral indoor cycles. In California, the diurnal temperature swings are big enough to be useful. :) This is what ntp sees the main/CPU crystal doing in a non airconditioned room. Each color is a different day. http://www.megapathdsl.net/~hmurray/ntp/slope.gif The swing would be much bigger outside, especially with an open sky. Since we'd be measuring 4 PPS signals that won't be in phase, I wasn't planning on sleeping for long. But, I some 10 usec sleeps with usleep(1) after reading a pulse would be reasonable. But, with the system not doing anything but polling and writing to the disk, I wasn't expecting much interruptions from other processes. I was thinking of keeping track of when you expected each pulse to arrive next and sleeping until a little before you expected the soonest one. (Adjust a little by trial and error.) This is a UNIX-like system? If so use a select on the file descriptor(s).This system call allows you to sleep until there is data available on one of a set of files. See man 2 select The code right after the select() has to poll all the files to see which one has data, your read/process it then go back an wait/sleep. If you do poll after a fixed length sleep you will on average to 1/2 of a polling cycle late reading the data and also you waste time checking when nothing is there. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
Hi Didier, Thanks for the idea. I haven't done any 8051 programming, but the price is great and you list other advantages on your web site. I appreciate the recommendation. Kevin A cheap way to measure temperature that will also be a good learning exercise would be to use a Silabs Toolstick. Most of their chips have a built in temperature sensor and a demo ADC program that spits out the temperature over the serial port emulated USB interface. The toolsticks are all about $10 and you need a Base Adapter that is $15 I believe. The tools are free (demo, size limited Keil compiler, or the free unlimited SDCC) More info on my web site in the Wiki http://www.ko4bb.com Alternately, you can buy a USB temperature sensor on eBay for about $10 I believe, but you won't learn much by using it... Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Kevin Rosenberg ke...@rosenberg.net Sender: time-nuts-boun...@febo.com Date: Tue, 4 Oct 2011 09:03:56 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] [Solved] Looking for multiple PPS timestamp logging On Oct 4, 2011, at 4:36 AM, Hal Murray wrote: In California, the diurnal temperature swings are big enough to be useful. :) Here in New Mexico as well, useful or ruinous depending upon your application. Hence, I believe, your smiley face above ;) The swing would be much bigger outside, especially with an open sky. We thought about an outdoor light and temperature sensor when my son considered measuring the stability of the PPS signal from a NetClock/2 WWVB receiver. But, we'll be measuring the temperature near the indoor XO. I was thinking of keeping track of when you expected each pulse to arrive next and sleeping until a little before you expected the soonest one. (Adjust a little by trial and error.) Sure, and the solution becomes more interesting the more pulse lines that are being polled. I agree that Tom's picPET will be a fine way to do it. I was just playing with how to do it with the parallel port. I lot of fine ideas come from thought experiments. It's still an interesting question of how accurate you need to measure the time. That's probably a good one to work through with your son on the back of an envelope. I think so, too. So, my son will be learning more about stability, Allan deviations, modified Allan deviations (which should be more useful for the number of averaging points over a month), and improving his exponent skills. Another statistic he'll be learning is the Pearson correlation coefficient to compare temperature (probably in Kelvin) to the XO frequency. The more precisely those are measured, the more likely the Pearson will reflect the true correlation. How are you measuring temperature? Good question, because we haven't completely solved that. We'll be using a LM35CAH mounted next to the 32768 crystal and measuring the voltage once a second. What I haven't decided is whether to have my son use the 34401A and GPIB polling via a Prologix adapter versus a simple MCU firmware using a 2.5V reference voltage and a 10-12 bit ADC and outputs the ADC result either once a second, or in response to a pulse (probably from the PPS of the XO). The first has merits of accuracy and simplicity, but I prefer he use more affordable devices than the 34401A in his experiment to even his project compared with other students. The latter has the advantage of price, but the disadvantage of me writing the firmware (though, the firmware is almost trivial). But again, I'd like him to be as independent as possible. So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendipitous time. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
Hi Jim, Thanks for the thought. I forgot about my Dataq DI-720 which can do 14-bit ADC. However, I'll need to spend more time looking at their acquisition software. I haven't seen a way to have WinDaq/Pro output an ASCII log file, though the software sheet talks about streaming disk files, it appears to be their proprietary format. BTW, I have an open-source program called wdq2wav to convert WinDaq files to .wav files @ http://wdq2wav.b9.com/ I haven't found a simple C API for the unit to allow me to write my own logging program for the DI-720. But, you have a good idea. I should give Dataq a call and find out what options I have for simple, continuous ASCII logging output. Kevin On Oct 4, 2011, at 9:40 AM, Jim Lux wrote: On 10/4/11 8:03 AM, Kevin Rosenberg wrote: So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendipitous time. DATAQ http://www.dataq.com/products/startkit/di145.html $29, 4 channel 10 bit ADC with USB interface You'll need to cobble up a sensor, of course, and I don't know if the resolution of the di145 is good enough (20mV/LSB as I recall) for a LM335 (10mV/Kelvin?). One thing you get with cheap is a +/- 10V full scale range. A thermistor and resistor into the DATAQ might work better. Maxim/Dallas One-Wire devices are another possibility There's tons of PIC code out there to interface to them. The sensors are cheap (few bucks, depending on whether you buy raw device, or you get one potted with a cable) Sparkfun.com has them, among other places. There's also a whole raft of USB temperature loggers out there from Onset (HOBO) or DataQ or a variety of other companies. They tend to run in the $80 range (if someone knows about a battery powered temperature logger in the under $25 range, I'd love to hear about it) And, of course, a DMM with a RS-232 interface is another possibility ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
On Oct 4, 2011, at 10:16 AM, Tijd Dingen wrote: You mentioned wanting to use the parallel port under linux for pps purposes, right? Hi Fred, I consider it, but tvb's picPET's will work much better for the project. So if some parallel port programming is acceptable, then you can do the following: - get an adc with SPI bus (which means plenty of choice) - connect the 3 SPI wires to parallel port - bitbang spi (just google bitbang spi and you'll find example code. it's pretty simple to do yourself and a fairly forgiving protocol (timing wise)) I like SPI as well and have done a fair bit of AVR bit banging. Doing it though the parallel port is intriguing. Alternatively you could use a microcontroller with both spi and uart (microchip and atmel have plenty), and use that to serve as uart -- spi bridge. Or for something like a 10 bit ADC you can use the internal adc of the MCU. I'm leaning toward an ATMega168 which has a USART and a TWI interface, so simplify programming and work at the byte rather than bit level. - get an ADS1258EVM board for about $50 - bring your own supply voltage - bitbang spi on the parallel port - bitbang i2c on the parallel port (this is optional for this board, not strictly needed) That's a nice board. I ended up ordering the PDK version which comes with a some other features including a USB interface so can skip worrying about having a parallel port on whatever system I'll be using the ADS1258EVM with. Creating a fpga interface like you did is a fine idea, but I'll end up trading some dollars for time with the PDK version. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
On Oct 4, 2011, at 9:10 AM, Bob Bownes wrote: If you need a simple/cheap pollable ADC, there is a Velleman kit available with USB. Can sample ADC, and a number of discrete inputs as well. And it can now be found on the wall at Radio Shack, strangely enough. Hi Bob, That's nice that it's available down the street, but for reading the LM35 at 0.20 to 0.28 V, the kit's 8-bit resolution will be lower than I'd like. Thanks for the idea -- I wasn't aware that RS was carrying Velleman kits. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
On 10/5/11 12:59 PM, shali...@gmail.com wrote: Jim, This is an interesting product, thank for the link! Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... There's also the Labjack product... http://www.labjack.com/ USB interface for events, ADC, etc. In the $100 range depending on the model. A few years ago when it first came out, it was a pain because it was Windows only, with limited protocol doc. But now they've got Linux, Mac, Windows, with bindings for just about every language -Original Message- From: Jim Luxjim...@earthlink.net Sender: time-nuts-boun...@febo.com Date: Tue, 04 Oct 2011 08:40:55 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] [Solved] Looking for multiple PPS timestamp logging On 10/4/11 8:03 AM, Kevin Rosenberg wrote: So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendipitous time. DATAQ http://www.dataq.com/products/startkit/di145.html $29, 4 channel 10 bit ADC with USB interface You'll need to cobble up a sensor, of course, and I don't know if the resolution of the di145 is good enough (20mV/LSB as I recall) for a LM335 (10mV/Kelvin?). One thing you get with cheap is a +/- 10V full scale range. A thermistor and resistor into the DATAQ might work better. Maxim/Dallas One-Wire devices are another possibility There's tons of PIC code out there to interface to them. The sensors are cheap (few bucks, depending on whether you buy raw device, or you get one potted with a cable) Sparkfun.com has them, among other places. There's also a whole raft of USB temperature loggers out there from Onset (HOBO) or DataQ or a variety of other companies. They tend to run in the $80 range (if someone knows about a battery powered temperature logger in the under $25 range, I'd love to hear about it) And, of course, a DMM with a RS-232 interface is another possibility ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
On Oct 5, 2011, at 7:49 PM, Jim Lux wrote: There's also the Labjack product... http://www.labjack.com/ USB interface for events, ADC, etc. In the $100 range depending on the model. A few years ago when it first came out, it was a pain because it was Windows only, with limited protocol doc. But now they've got Linux, Mac, Windows, with bindings for just about every language Cool gadgets. Thanks for the link! Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
The temperature swings won't be large, just the usual diuneral indoor cycles. In California, the diurnal temperature swings are big enough to be useful. :) This is what ntp sees the main/CPU crystal doing in a non airconditioned room. Each color is a different day. http://www.megapathdsl.net/~hmurray/ntp/slope.gif The swing would be much bigger outside, especially with an open sky. Since we'd be measuring 4 PPS signals that won't be in phase, I wasn't planning on sleeping for long. But, I some 10 usec sleeps with usleep(1) after reading a pulse would be reasonable. But, with the system not doing anything but polling and writing to the disk, I wasn't expecting much interruptions from other processes. I was thinking of keeping track of when you expected each pulse to arrive next and sleeping until a little before you expected the soonest one. (Adjust a little by trial and error.) I agree that Tom's picPET will be a fine way to do it. I was just playing with how to do it with the parallel port. It's still an interesting question of how accurate you need to measure the time. That's probably a good one to work through with your son on the back of an envelope. How are you measuring temperature? -- 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] [Solved] Looking for multiple PPS timestamp logging
On Oct 4, 2011, at 4:36 AM, Hal Murray wrote: In California, the diurnal temperature swings are big enough to be useful. :) Here in New Mexico as well, useful or ruinous depending upon your application. Hence, I believe, your smiley face above ;) The swing would be much bigger outside, especially with an open sky. We thought about an outdoor light and temperature sensor when my son considered measuring the stability of the PPS signal from a NetClock/2 WWVB receiver. But, we'll be measuring the temperature near the indoor XO. I was thinking of keeping track of when you expected each pulse to arrive next and sleeping until a little before you expected the soonest one. (Adjust a little by trial and error.) Sure, and the solution becomes more interesting the more pulse lines that are being polled. I agree that Tom's picPET will be a fine way to do it. I was just playing with how to do it with the parallel port. I lot of fine ideas come from thought experiments. It's still an interesting question of how accurate you need to measure the time. That's probably a good one to work through with your son on the back of an envelope. I think so, too. So, my son will be learning more about stability, Allan deviations, modified Allan deviations (which should be more useful for the number of averaging points over a month), and improving his exponent skills. Another statistic he'll be learning is the Pearson correlation coefficient to compare temperature (probably in Kelvin) to the XO frequency. The more precisely those are measured, the more likely the Pearson will reflect the true correlation. How are you measuring temperature? Good question, because we haven't completely solved that. We'll be using a LM35CAH mounted next to the 32768 crystal and measuring the voltage once a second. What I haven't decided is whether to have my son use the 34401A and GPIB polling via a Prologix adapter versus a simple MCU firmware using a 2.5V reference voltage and a 10-12 bit ADC and outputs the ADC result either once a second, or in response to a pulse (probably from the PPS of the XO). The first has merits of accuracy and simplicity, but I prefer he use more affordable devices than the 34401A in his experiment to even his project compared with other students. The latter has the advantage of price, but the disadvantage of me writing the firmware (though, the firmware is almost trivial). But again, I'd like him to be as independent as possible. So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendipitous time. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
On 10/4/11 8:03 AM, Kevin Rosenberg wrote: So, if you know of any simple ADC to UART firmwares available, that'd be great so he can just reference someone else's code. The picPET is a perfect device at the perfect time. But, we can't rely on tvb to come up with a 'picADC' at a similarly serendipitous time. DATAQ http://www.dataq.com/products/startkit/di145.html $29, 4 channel 10 bit ADC with USB interface You'll need to cobble up a sensor, of course, and I don't know if the resolution of the di145 is good enough (20mV/LSB as I recall) for a LM335 (10mV/Kelvin?). One thing you get with cheap is a +/- 10V full scale range. A thermistor and resistor into the DATAQ might work better. Maxim/Dallas One-Wire devices are another possibility There's tons of PIC code out there to interface to them. The sensors are cheap (few bucks, depending on whether you buy raw device, or you get one potted with a cable) Sparkfun.com has them, among other places. There's also a whole raft of USB temperature loggers out there from Onset (HOBO) or DataQ or a variety of other companies. They tend to run in the $80 range (if someone knows about a battery powered temperature logger in the under $25 range, I'd love to hear about it) And, of course, a DMM with a RS-232 interface is another possibility ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
On Tue, Oct 4, 2011 at 3:36 AM, Hal Murray hmur...@megapathdsl.net wrote: The temperature swings won't be large, just the usual diuneral indoor cycles. In California, the diurnal temperature swings are big enough to be useful. :) This is what ntp sees the main/CPU crystal doing in a non airconditioned room. Each color is a different day. http://www.megapathdsl.net/~hmurray/ntp/slope.gif The swing would be much bigger outside, especially with an open sky. Since we'd be measuring 4 PPS signals that won't be in phase, I wasn't planning on sleeping for long. But, I some 10 usec sleeps with usleep(1) after reading a pulse would be reasonable. But, with the system not doing anything but polling and writing to the disk, I wasn't expecting much interruptions from other processes. I was thinking of keeping track of when you expected each pulse to arrive next and sleeping until a little before you expected the soonest one. (Adjust a little by trial and error.) This is a UNIX-like system? If so use a select on the file descriptor(s).This system call allows you to sleep until there is data available on one of a set of files. See man 2 select The code right after the select() has to poll all the files to see which one has data, your read/process it then go back an wait/sleep. If you do poll after a fixed length sleep you will on average to 1/2 of a polling cycle late reading the data and also you waste time checking when nothing is there. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
Thank you to everyone for their thought answers and insights, they gave me some great ideas. I was thinking about the parallel port polling idea, but then my son wanted to measure the relation between temperature and XO frequency, so we needed microsecond resolution. tvb came up with just the perfect solution: - Cheap, $5 per part - Easy for my son to construct, an 8-pin PIC and a bypass capacitor for each PPS line - Easy to analyze results, one ASCII text line for each input pulse - Continuously counting indefinitely - sub-microsecond resolution (useful for measuring tempc for an XO) Thanks again to everyone for their good thoughts and valuable time spent considering my question. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
I was thinking about the parallel port polling idea, but then my son wanted to measure the relation between temperature and XO frequency, so we needed microsecond resolution. Why do you need microsecond resolution? A junk XO will drift ballpark of 1 PPM per C. That's 86 ms per day or 3.6 ms per hour. What sort of resolution do you think you can get from a parallel port? It might be fun to see how far you can push the parallel port. How about a loop like this: Initialization: grab old time grab old parallel port data loop: grab new time grab new parallel port data if data changed: grab newer time log change that happened somewhere between old time and newer time old time = new time old data = new data goto loop Post processing can filter out the occasional samples with a wide time window because the scheduler ran some other job at the wrong time. For extra credit... Suppose you are expecting PPS type signals and you know roughly where they are located within a second. There is no point is spinning when you aren't expecting something to happen. So you can sleep until a bit before the next event. That will let the scheduler run other jobs. Hopefully it will be nicer to you when you do want to run. -- 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] [Solved] Looking for multiple PPS timestamp logging
Hi Hal: been watching this thread with some interest. Seems to me that the layers that the MS operating systems and bios(es) put between the parallel port and the programs using the port could introduce a lot of variable latency. I think there may be some available dll's that go around the shells? Don Hal Murray I was thinking about the parallel port polling idea, but then my son wanted to measure the relation between temperature and XO frequency, so we needed microsecond resolution. Why do you need microsecond resolution? A junk XO will drift ballpark of 1 PPM per C. That's 86 ms per day or 3.6 ms per hour. What sort of resolution do you think you can get from a parallel port? It might be fun to see how far you can push the parallel port. How about a loop like this: Initialization: grab old time grab old parallel port data loop: grab new time grab new parallel port data if data changed: grab newer time log change that happened somewhere between old time and newer time old time = new time old data = new data goto loop Post processing can filter out the occasional samples with a wide time window because the scheduler ran some other job at the wrong time. For extra credit... Suppose you are expecting PPS type signals and you know roughly where they are located within a second. There is no point is spinning when you aren't expecting something to happen. So you can sleep until a bit before the next event. That will let the scheduler run other jobs. Hopefully it will be nicer to you when you do want to run. -- 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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
Hal, Don, I too have tried all the PC-based (serial/parallel port) solutions. As we discussed at lot with the TEC thread, they work pretty well. But for general use, or stand-alone operation, what I use for dirt cheap non-nanosecond timing is a TBolt-10MHz-driven isochronous microcontroller. tvb came up with just the perfect solution: Details here: http://www.leapsecond.com/pic/picpet.htm /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] [Solved] Looking for multiple PPS timestamp logging
On Oct 3, 2011, at 12:59 PM, Hal Murray wrote: Why do you need microsecond resolution? A junk XO will drift ballpark of 1 PPM per C. That's 86 ms per day or 3.6 ms per hour. The temperature swings won't be large, just the usual diuneral indoor cycles. He wants to use compute much much of the frequency change can be explained by temperature alone, we were going to measure temperature and frequency as precisely as is reasonable cost. So, it would be nice to measure a microsecond difference in a second if the temperature very suddenly changed by 1 degree C. What sort of resolution do you think you can get from a parallel port? I think the point it moot now that tvb has the very useful picPET for this application. I think resolution will depend upon the load of the OS. I was going to use an old PC running linux and no graphics mode. I think sub-millisecond stability is a reasonable expectation. So, probably need to use fatPPS for the 10 usec PRS10 PPS. It might be fun to see how far you can push the parallel port. How about a loop like this: [...] Yes, that about the flow that I was contemplating. I also planned to use optoisolators on the input pins from the readings I did on interfacings with a parallel port. For extra credit... Suppose you are expecting PPS type signals and you know roughly where they are located within a second. There is no point is spinning when you aren't expecting something to happen. So you can sleep until a bit before the next event. That will let the scheduler run other jobs. Hopefully it will be nicer to you when you do want to run. Since we'd be measuring 4 PPS signals that won't be in phase, I wasn't planning on sleeping for long. But, I some 10 usec sleeps with usleep(1) after reading a pulse would be reasonable. But, with the system not doing anything but polling and writing to the disk, I wasn't expecting much interruptions from other processes. But, I really like Tom's picPET, not just for this project, but after my son's project, I'm going to use 4 picPETs to measure stability across my group of Thunderbolts of varying vintage as well as comparing long-term drift across some Rb oscillators. Thanks again for the excellent parallel polling idea. I was going to go with that plan before Tom letting me know about his picPETs. Kevin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
Excellent, Tom. I missed it! Don Tom Van Baak Hal, Don, I too have tried all the PC-based (serial/parallel port) solutions. As we discussed at lot with the TEC thread, they work pretty well. But for general use, or stand-alone operation, what I use for dirt cheap non-nanosecond timing is a TBolt-10MHz-driven isochronous microcontroller. tvb came up with just the perfect solution: Details here: http://www.leapsecond.com/pic/picpet.htm /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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
That looks like a great solution for monitoring oscillators/GPSDOs. Where to find an application that inputs RS232 and writes a file? cheers, Neville Michie On 04/10/2011, at 6:54 AM, Tom Van Baak wrote: Hal, Don, I too have tried all the PC-based (serial/parallel port) solutions. As we discussed at lot with the TEC thread, they work pretty well. But for general use, or stand-alone operation, what I use for dirt cheap non-nanosecond timing is a TBolt-10MHz-driven isochronous microcontroller. tvb came up with just the perfect solution: Details here: http://www.leapsecond.com/pic/picpet.htm /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. ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
On 10/3/11 5:20 PM, Neville Michie wrote: That looks like a great solution for monitoring oscillators/GPSDOs. Where to find an application that inputs RS232 and writes a file? Hyperterm? Minicom? in a DOS box mode COMn:9600,n,8,1 copy COMn filename You could suffer great mental pain and use one of the various .NET flavors, each of which has a different interface to the com ports, and crank out something in Visual C# Express Edition. ___ time-nuts mailing 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] [Solved] Looking for multiple PPS timestamp logging
I use a freebie language called Robot Basic. It is very flexible, easy to use, has a yahoo group of users, and the price is right! It will run on any of the Win os's and does not require installation, that is does not use the pesky .net or the registry. .exe files can be made, too. Don Neville Michie That looks like a great solution for monitoring oscillators/GPSDOs. Where to find an application that inputs RS232 and writes a file? cheers, Neville Michie On 04/10/2011, at 6:54 AM, Tom Van Baak wrote: Hal, Don, I too have tried all the PC-based (serial/parallel port) solutions. As we discussed at lot with the TEC thread, they work pretty well. But for general use, or stand-alone operation, what I use for dirt cheap non-nanosecond timing is a TBolt-10MHz-driven isochronous microcontroller. tvb came up with just the perfect solution: Details here: http://www.leapsecond.com/pic/picpet.htm /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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Solved] Looking for multiple PPS timestamp logging
That looks like a great solution for monitoring oscillators/GPSDOs. Where to find an application that inputs RS232 and writes a file? I don't think you need anything very complex for that. One could simply cat the serial port device to a log file cat /dev/tty01 | somename.log I see someone beat me to it. ;) Although around here we do: cat /dev/ttyS0 somename.log and cat /dev/ttyS0 | five_seconds_of_perl.pl Anyone who could build a uP powered device could figure out somethig even nicer in about 5 seconds using Perl, Python or whatever. My thoughts exactly. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
