Re: [time-nuts] RasberryPi, timing and GPS receivers
On Tue, 16 Oct 2012 15:06:19 -0600 x...@darksmile.net wrote: Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? I would go for the LEA modules. For once because you get pretty complete documentation for them (for free, w/o NDA) and because you can get the older modules (like LEA4-S) for 20-30CHF on ebay. Yes, they are not timing receivers, but the datasheet specs the PPS output as better than 60ns, which is for the use of an ntp server more than good enough. The newer ones are footprint compatible (modulo new function pins) and with a little care when doing the design you can solder all from LEA4 to LEA6 onto the same board without changes. A new LEA6-T single piece cost IIRC 190EUR from the webshop. A LEA5-T was IIRC half price. And a little caution: the LEA5 modules use considerably more power during aquisition than the LEA4 did and the LEA6. IIRC we measured up to 150mA (compared to 100mA with LEA4). I don't know the Rasberry, but i guess that should be not a proble, but you should check for it nevertheless. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
On Tue, Oct 16, 2012 at 7:03 PM, x...@darksmile.net wrote: The miniITX mobos are quite impressive. There is no argument there. However, My simple idea was this: Since I want to keep time at 3 separate locations and wanted stratum 1 NTP, I didn't want overkill. What is your accuracy requirement?You say you don't want overkill So I assume you would be happy with 50 millisecond error? That is 1/20th second or do you need microseconds? No one can know if your plan is reasonable without knowing the goal. 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] RasberryPi, timing and GPS receivers
Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX Hi George, Welcome back to the list; you've been quiet for a long time. This sounds like a great project. I hope you keep us informed with progress and also make the results available. You should be able to find GPS modules with sub-microsecond 1PPS for $25. Check sparkfun.com or the Skylab chip used on the www.leapsecond.com/pages/MG1613S board. This and other chip solutions require SMT/PCB mounting, connectors, external antenna and cabling which can add to the net cost of complexity. A number of people I know who want an inexpensive, turn-key, sub-microsecond, embedded GPS timing solution continue to chose the Garmin 18x/LVC. These are nice because of the high-gain integrated antenna (they work indoors), compact encapsulated design, and extreme ease of use (5V, ground, 1PPS). /tvb A new LEA6-T single piece cost IIRC 190EUR from the webshop. A LEA5-T was IIRC half price. And a little caution: the LEA5 modules use considerably more power during aquisition than the LEA4 did and the LEA6. IIRC we measured up to 150mA (compared to 100mA with LEA4). I don't know the Rasberry, but i guess that should be not a proble, but you should check for it nevertheless. Attila Kinali Attila, I'd say the u-blox 5T or 6T is rather over-kill for George's application, both in price and performance (and learning curve and integration). Remember that the world of NTP is milli- and microseconds. State-of-the-art GPS timing receivers and GPSDO are in the nano- and picosecond accuracy/jitter range. /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] RasberryPi, timing and GPS receivers
Moin, On Wed, 17 Oct 2012 11:42:06 -0700 Tom Van Baak t...@leapsecond.com wrote: A new LEA6-T single piece cost IIRC 190EUR from the webshop. A LEA5-T was IIRC half price. And a little caution: the LEA5 modules use considerably more power during aquisition than the LEA4 did and the LEA6. IIRC we measured up to 150mA (compared to 100mA with LEA4). I don't know the Rasberry, but i guess that should be not a proble, but you should check for it nevertheless. I'd say the u-blox 5T or 6T is rather over-kill for George's application, both in price and performance (and learning curve and integration). Remember that the world of NTP is milli- and microseconds. State-of-the-art GPS timing receivers and GPSDO are in the nano- and picosecond accuracy/jitter range Yes, that's why i explicitly mentioned the LEA4-S, which already is way more accurate than ntp can get over the network. A LEA5-S sells for 16USD on ebay. For 30USD you already get a soldered board with an NEO6-M and patch antenna. All you need to do to use those is to solder a wire for the PPS pin and you're set. With such little money you get a top modern GPS module with high sensitivity (even the LEA4 could get reasonable indoor reception with a simple passive patch antenna, and the LEA6/NEO6 are much better) and more than good enough PPS output (60ns w/o sawtooh correction) At these prices, i'm surprised that not more people are using the u-blox modules for their stuff. Attila Kinali -- There is no secret ingredient -- Po, Kung Fu Panda ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
Tom, Thank you and nice to be back! Was working major hours for a while. Workin' for a living :) Now, I must confess that this project is sort of a milestone for me. Those who hate kids (I know you are out there !) can stop reading now :) My daughter, who just turned six, has been very curious about what I do with all my machines. I have taught her how to properly solder and she can spot a cold joint and is very adamant about such things. So, I have been thinking about making a small project with lights etc. I don't have that much time and I also want to experiment with the RPI so, I can combine projects. Given that an NTP server will not be as much fun in terms of lights and so on, but I think it will be more fun when the intricacies of time are explained. She is already very interested in puzzles and stuff so I figure I'll encourage her. I was actually very sneaky with getting her interested in puzzles and stuff. You see we both love Gravity Falls which is this amazing Disney Channel series that has crazy puzzles in it and it is a challenge to figure out what is hiding in each episode. Using that as the start, I explained more things to her about puzzles and math and she absolutely loves it. So, to sum up (and sorry for the long post) I think an NTP server with a tiny footprint is just the ticket. Your comments are most welcome. Oh, and it would be nice to get micro-second accuracy. George, N2FGX Quoting Tom Van Baak t...@leapsecond.com: Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX Hi George, Welcome back to the list; you've been quiet for a long time. This sounds like a great project. I hope you keep us informed with progress and also make the results available. You should be able to find GPS modules with sub-microsecond 1PPS for $25. Check sparkfun.com or the Skylab chip used on the www.leapsecond.com/pages/MG1613S board. This and other chip solutions require SMT/PCB mounting, connectors, external antenna and cabling which can add to the net cost of complexity. A number of people I know who want an inexpensive, turn-key, sub-microsecond, embedded GPS timing solution continue to chose the Garmin 18x/LVC. These are nice because of the high-gain integrated antenna (they work indoors), compact encapsulated design, and extreme ease of use (5V, ground, 1PPS). /tvb A new LEA6-T single piece cost IIRC 190EUR from the webshop. A LEA5-T was IIRC half price. And a little caution: the LEA5 modules use considerably more power during aquisition than the LEA4 did and the LEA6. IIRC we measured up to 150mA (compared to 100mA with LEA4). I don't know the Rasberry, but i guess that should be not a proble, but you should check for it nevertheless. Attila Kinali Attila, I'd say the u-blox 5T or 6T is rather over-kill for George's application, both in price and performance (and learning curve and integration). Remember that the world of NTP is milli- and microseconds. State-of-the-art GPS timing receivers and GPSDO are in the nano- and picosecond accuracy/jitter range. /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.
[time-nuts] RasberryPi, timing and GPS receivers
Hello everyone, I started a new project for myself where I would use the RasperryPi Linux board as a NTP server. My goal is to design a custom board for the Pi and mount a GPS receiver on it. With this combination, I should be able to configure NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. The new RasberryPI has 512MB memory so it should be fine for running just ntpd. Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
uBlox LEA-5T, LEA6-T? SkyTraq Venus5? On Tue, Oct 16, 2012 at 11:06 PM, x...@darksmile.net wrote: Hello everyone, I started a new project for myself where I would use the RasperryPi Linux board as a NTP server. My goal is to design a custom board for the Pi and mount a GPS receiver on it. With this combination, I should be able to configure NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. The new RasberryPI has 512MB memory so it should be fine for running just ntpd. Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
I have a similar setup and running now (minus the custom pcb) using a Venus638FLPx module from Sparkfun (~$50 + antenna). The module was easy to configure and had a decent 1PPS output. So far, everything is working (hardware-wise, I still have some NTP settings to tweak). I have the 256MB version of the Pi and it seems to handle the load just fine. Open Systems International, Inc. Zach Davis Software Development 4101 Arrowhead Drive Medina, Minnesota 55340-9457 Phone: 763 551 0559 Fax: 763 551 0750 E-mail: zach.da...@osii.com Website: http://www.osii.com/ -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of x...@darksmile.net Sent: Tuesday, October 16, 2012 4:06 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] RasberryPi, timing and GPS receivers Hello everyone, I started a new project for myself where I would use the RasperryPi Linux board as a NTP server. My goal is to design a custom board for the Pi and mount a GPS receiver on it. With this combination, I should be able to configure NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. The new RasberryPI has 512MB memory so it should be fine for running just ntpd. Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
On 10/16/2012 05:06 PM, x...@darksmile.net wrote: My goal is to design a custom board for the Pi and mount a GPS receiver on it. With this combination, I should be able to configure NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. The new RasberryPI has 512MB memory so it should be fine for running just ntpd. Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? It's not a terrible idea, but the RPI has a USB ethernet transceiver so in addition to the latency/jitter of the ethernet it also has the latency/jitter of the USB. I've also heard of stability problems just keeping it running for weeks to months so you should integrate some kind of watchdog timer if you can. The actual GPS module doesn't matter much since NTP will smooth out even the worst GPS jitter. I have heard second-hand (or third-hand or fourth-...) that some have a significant persistent delay and that could be more of a problem. If you want to go for a timing-oriented receiver you can get a used Trimble Resolution T from ebay but they have a 2mm pitch header. You will want to house the RPI and GPS receiver in a box where it will not be subject to wide temperature swings, insulated and shielded from drafts. It would also be interesting to upgrade the main oscillator to a temperature-compensated model so NTP doesn't have to work as hard to keep the frequency locked. Personally I would recommend getting a more robust single-board computer, e.g. a PC Engines ALIX or Olimex olinuxino. RPI is cheap but hard to source, not open-source, and does not have good long-term prospects due to the microprocessor being used. Most of the attention is due to deliberate publicity by the manufacturer and not novelty or merit. If you must use the cheapest board then by all means do so, but just know there is better available for not much more. Happy ticking, -- m. tharp ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
Michael, Thank you for your most valuable information. This is why time-nuts is so amazing! My goal is actually two-fold. First, I would like to have a NTP server that I can easily hook up (well, as easily as possible) without dedicating a Linux server each time. My personal use would require 3 separate NTP servers because I am a time-nut and stratum 2 is not an option. The idea here is to create a smart piggy-back architecture where the CPU/Ethernet sits on the bottom with (perhaps) a few modules on top of that with GPS right on top (let's call it the penthouse). For obvious reasons I would put the Power supply separately. So we are looking for a very small footprint NTP server. Now, I thought the RasberryPi would be ok even though I did not like the limitations you mentioned as well. It is very popular. You mentioned the Olimex olinuxino. Wow! This is a thing of beauty indeed! https://www.olimex.com/Products/OLinuXino/A13/A13-OLinuXino/ I really like this board. My second goal is that if I go to the trouble of creating a GPS-daughterboard and all that I'd like to have other people use it as well and maybe I would make a small batch. Cost wise this should be in the 10-20 dollar range tops. I think I will do some research on this board and maybe order one. It looks very promising. I wonder if I can replace the crystal with a better high stability one. -George Quoting Michael Tharp g...@partiallystapled.com: On 10/16/2012 05:06 PM, x...@darksmile.net wrote: My goal is to design a custom board for the Pi and mount a GPS receiver on it. With this combination, I should be able to configure NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. The new RasberryPI has 512MB memory so it should be fine for running just ntpd. Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? It's not a terrible idea, but the RPI has a USB ethernet transceiver so in addition to the latency/jitter of the ethernet it also has the latency/jitter of the USB. I've also heard of stability problems just keeping it running for weeks to months so you should integrate some kind of watchdog timer if you can. The actual GPS module doesn't matter much since NTP will smooth out even the worst GPS jitter. I have heard second-hand (or third-hand or fourth-...) that some have a significant persistent delay and that could be more of a problem. If you want to go for a timing-oriented receiver you can get a used Trimble Resolution T from ebay but they have a 2mm pitch header. You will want to house the RPI and GPS receiver in a box where it will not be subject to wide temperature swings, insulated and shielded from drafts. It would also be interesting to upgrade the main oscillator to a temperature-compensated model so NTP doesn't have to work as hard to keep the frequency locked. Personally I would recommend getting a more robust single-board computer, e.g. a PC Engines ALIX or Olimex olinuxino. RPI is cheap but hard to source, not open-source, and does not have good long-term prospects due to the microprocessor being used. Most of the attention is due to deliberate publicity by the manufacturer and not novelty or merit. If you must use the cheapest board then by all means do so, but just know there is better available for not much more. Happy ticking, -- m. tharp ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
I've been looking at the Raspberry Pi for a number of projects as well, and have been running one for a few weeks. My take on the early stability concerns/complaints are that the majority of those are due to poor power supplies, with some assistance from the Raspberry Pi design. Measure what you have for DC at TP1 and TP2; it should be close to 5 volts. The polyswitch self-resetting fuse on the power input introduces series resistance (in the wrong place); on my unit it measures 0.36 ohms (4-wire measurement with my HP33401A). Couple this with a cheepie USB supply that's already below 5 volts, and you're on thin ice. Do anything that spikes power consumption, such as Ethernet, GPU, or plugging in USB devices, and you generate more of an IR drop across the polyswitch which can cause erratic operation or resets. Use a good power supply -- 5 volts at an amp. Adafruit sells one that's 5V/2A for under $10. Or you can bypass some of the protection components and connect your +5 supply to TP1 and TP2. Running mine from a solid power source the only problems I've had are with my own crummy code... Bob K6RTM -- Message: 5 Date: Tue, 16 Oct 2012 15:06:19 -0600 From: x...@darksmile.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] RasberryPi, timing and GPS receivers Message-ID: 20121016150619.16306sbpxvjy8...@darksmile.net Content-Type: text/plain; charset=ISO-8859-1; DelSp=Yes; format=flowed Hello everyone, I started a new project for myself where I would use the RasperryPi Linux board as a NTP server. My goal is to design a custom board for the Pi and mount a GPS receiver on it. With this combination, I should be able to configure NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. The new RasberryPI has 512MB memory so it should be fine for running just ntpd. Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
Michael Tharp g...@partiallystapled.com wrote [RE: raspberry pi ntp server] It's not a terrible idea, but the RPI has a USB ethernet transceiver so in addition to the latency/jitter of the ethernet it also has the latency/jitter of the USB. I've been playing with a pair of Raspberry Pi ntp servers, one with a $15 Sure Electronics GPS evaluation board, which was very easy to interface to (3.3v uart and pps outputs) and the other connected to a Lucent RFTG, which once I figured out that the Pi apparenty tolerates the PPS out from the RFTG w/o a level shifter just fine (mostly - I was getting false extra pulses until I shielded the line, which I hadn't needed to do on the Sure GPS board). I'm a junior time-nut at best but it looks to me like jitter from the USB Ethernet is acceptably low, based on ntpq -p anyway: remote refid st t when poll reach delay offset jitter == oGPS_NMEA(0) .GPS.0 l2 16 3770.0000.003 0.004 +pi2 .PPS.1 s7 16 3770.945 -0.004 0.044 +pool-test.ntp.o 216.218.192.202 2 u 43 64 377 73.8551.382 0.262 remote refid st t when poll reach delay offset jitter == oPPS(0) .PPS.0 l18 3770.000 -0.024 0.061 +ntp .GPS.1 s 148 2520.9830.217 0.615 *tick.nullmodem. 128.252.19.1 2 u 60 64 377 35.0660.562 4.556 Some of the offset between the two might be that I am waiting for a 2nd GPS antenna to arrive for the RFTG and it's been undisciplined for a few days, it might be from the ethernet jitter, the Sure GPS might be off, or it might be from the fact that I may have a configuration issue someplace - ntpq -c rl has them at different precisions (-19 and -18), even though I think they're the same kernel and ntpd compile. I've also heard of stability problems just keeping it running for weeks to months so you should integrate some kind of watchdog timer if you can. I haven't seen the issue yet but I haven't been running more than a couple of weeks. Part of the problem may be quality of power supply, I've seen some people reporting issues if the 5v usb power in isn't capable of providing enough current and a stable voltage. You will want to house the RPI and GPS receiver in a box where it will not be subject to wide temperature swings, I haven't been running either of mine in an enclosure, both are sitting up in the unheated attic at the moment, typical offsets from loopstats seem to be under 2us, but I should graph them. It would also be interesting to upgrade the main oscillator to a temperature-compensated model so NTP doesn't have to work as hard to keep the frequency locked. I am curious if I could replace the 19.2mhz system clock crystal with a stable source generated from the 15mhz RFTG output via a clockblock, ala what I have seen reported about the Soekris. Personally I would recommend getting a more robust single-board computer I don't disagree that the Pi has its flaws but it has been fun to play with. -shaun ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
Annoyance with small Linux boards: My single biggest annoyance is that all the I/O connectors are coming out from all 4 directions. What I mean is this: It would be nice to have ethernet+LEDs+USB+VGA(HDMI) come out from one side, and Power/I/O/RS232 from the opposite side. This way if I make a case I only need to worry about what is coming out of the Ethernet side. The RPI has ethernet+usb on one side and HDMI from another. How do you make a decent case with only one side open? It is impossible. If they only had the HDMI on a header so I can break it out. Same for audio/USB -George Quoting sh...@impsec.net sh...@impsec.net: Michael Tharp g...@partiallystapled.com wrote [RE: raspberry pi ntp server] It's not a terrible idea, but the RPI has a USB ethernet transceiver so in addition to the latency/jitter of the ethernet it also has the latency/jitter of the USB. I've been playing with a pair of Raspberry Pi ntp servers, one with a $15 Sure Electronics GPS evaluation board, which was very easy to interface to (3.3v uart and pps outputs) and the other connected to a Lucent RFTG, which once I figured out that the Pi apparenty tolerates the PPS out from the RFTG w/o a level shifter just fine (mostly - I was getting false extra pulses until I shielded the line, which I hadn't needed to do on the Sure GPS board). I'm a junior time-nut at best but it looks to me like jitter from the USB Ethernet is acceptably low, based on ntpq -p anyway: remote refid st t when poll reach delay offset jitter == oGPS_NMEA(0) .GPS.0 l2 16 3770.000 0.003 0.004 +pi2 .PPS.1 s7 16 3770.945 -0.004 0.044 +pool-test.ntp.o 216.218.192.202 2 u 43 64 377 73.855 1.382 0.262 remote refid st t when poll reach delay offset jitter == oPPS(0) .PPS.0 l18 3770.000 -0.024 0.061 +ntp .GPS.1 s 148 2520.983 0.217 0.615 *tick.nullmodem. 128.252.19.1 2 u 60 64 377 35.066 0.562 4.556 Some of the offset between the two might be that I am waiting for a 2nd GPS antenna to arrive for the RFTG and it's been undisciplined for a few days, it might be from the ethernet jitter, the Sure GPS might be off, or it might be from the fact that I may have a configuration issue someplace - ntpq -c rl has them at different precisions (-19 and -18), even though I think they're the same kernel and ntpd compile. I've also heard of stability problems just keeping it running for weeks to months so you should integrate some kind of watchdog timer if you can. I haven't seen the issue yet but I haven't been running more than a couple of weeks. Part of the problem may be quality of power supply, I've seen some people reporting issues if the 5v usb power in isn't capable of providing enough current and a stable voltage. You will want to house the RPI and GPS receiver in a box where it will not be subject to wide temperature swings, I haven't been running either of mine in an enclosure, both are sitting up in the unheated attic at the moment, typical offsets from loopstats seem to be under 2us, but I should graph them. It would also be interesting to upgrade the main oscillator to a temperature-compensated model so NTP doesn't have to work as hard to keep the frequency locked. I am curious if I could replace the 19.2mhz system clock crystal with a stable source generated from the 15mhz RFTG output via a clockblock, ala what I have seen reported about the Soekris. Personally I would recommend getting a more robust single-board computer I don't disagree that the Pi has its flaws but it has been fun to play with. -shaun ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
On 10/16/2012 06:28 PM, sh...@impsec.net wrote: I'm a junior time-nut at best but it looks to me like jitter from the USB Ethernet is acceptably low, based on ntpq -p anyway: It's a minor problem at worst. There are many worse conflating factors and NTP adjusts very slowly anyway to deal with receiving time over the internet. Supporting a more precise protocol like PTP, or even better CERN's White Rabbit extensions to it, is another matter and at that point you're using all custom hardware including switches. Not good for the bank account. That said, I have considered a project almost identical to what George is describing -- a very simple Linux-powered board that consumes negligible power and whose sole purpose in life is to run a NTP server from GPS. My focus was on doing it from scratch as a single PCB (except the GPS module, for now), but it seems the choices for easily sourceable Linux-capable microprocessors that are in 1mm BGA, let alone non-BGA, can be counted on one hand. AM1707 was the chip that I would use for the off the shelf microprocessor approach. It may actually be more effective -- and cool -- to use a FPGA and implement a microprocessor inside that instead! I have booted linux on a ORPSoC soft processor, but that was on a $300 dev board. Scaling it down to a cheap single-board computer would be challenging but not unthinkable. That particular SoC requires quite a lot of FPGA resources so something else would be required to avoid needing a $30 FPGA. But my current plans, not fully baked nor on any sort of schedule, involve neither linux nor a conventional ntpd. I'm designing a low-cost GPSDO around an ARM microcontroller that keeps its own time and is capable of acting as a dumb NTP server -- it would respond to requests from clients but would not receive time from other nodes. The loop would be stabilized solely by GPS although the loop algorithms will probably be adopted from NTPns because they are quite similar to what the GPSDO itself needs to do. I was originally planning to only support an ovenized oscillator as the LO, but it would also be possible to use a tunable TXCO or perhaps a small OCXO that could reside on the board and not take up much space or power. Connect 3 of these to the network and you've got a great stratum 1 pool. Right now I have a prototype GPSDO working although the loop algorithm is amateurish. I've been putting off working on it for a few weeks now, I need to sit down and study NTPns so I can implement a similar algorithm. The current one would be good enough for NTP but does not yet track time of day. The network components are not in the prototype, but I have written some sample code into another project that does have ethernet and it seems to work, so putting the two pieces together should result in a great NTP server. Oh dear, now I've written quite a lot and probably raised some eyebrows. Better quit while I'm behind. Happy ticking, -- m. tharp ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
On Tue, Oct 16, 2012 at 3:26 PM, x...@darksmile.net wrote: Michael, Thank you for your most valuable information. This is why time-nuts is so amazing! My goal is actually two-fold. First, I would like to have a NTP server that I can easily hook up (well, as easily as possible) without dedicadting a Linux server each time. One does NOT need a dedicated server for NTP. NTP can run on a linux system that is also a web and mail server or on e linux desktop system that you use for web surfing and web browse ring, just as long as the box stays running and you don't turn it off. My personal use would require 3 separate NTP servers because I am a time-nut and stratum 2 is not an option. What level of accuracy is required? Don't say as good as posable because that can be quite expensive. What really do you need? About the best you can expect from NTP without exotic hardware is 2 u-sec level. But maybe you'd be happy with 2 milli seconds. The idea here is to create a smart piggy-back architecture where the CPU/Ethernet sits on the bottom with (perhaps) a few modules on top of that with GPS right on top (let's call it the penthouse). Remember that you cn buy a fully integrated Intel Atom mainboard that is a bout 6 square and uses only a few watts for $90. The Atom will run NTP and mail and web servers and allow web surfing all at the same time and costs $90 including the soldered down CPU. It will have a real RS232 port and a good built-in Eithernet. These boards don't require fan cooling. For obvious reasons I would put the Power supply separately. Why? I hate power cubes So we are looking for a very small footprint NTP server. Now, I thought the RasberryPi would be ok even though I did not like the limitations you mentioned as well. It is very popular. It is popular for some applications. But a statum 1 NTP server needs the PPS from the GPS to go to a hardware interrupt and it needs a solid Ethernet controller with low latency. You mentioned the Olimex olinuxino. Wow! This is a thing of beauty indeed! https://www.olimex.com/Products/OLinuXino/A13/A13-OLinuXino/ Look at this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442 It is directly usable for NTP with no circuit design or soldering and the NTP server will run at the few u-sec level while also running as a file seder, web server and runing LLady Heather inside a virtual Windows under VMware. Not heat or fan noise. -- 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] RasberryPi, timing and GPS receivers
One does NOT need a dedicated server for NTP. NTP can run on a linux system that is also a web and mail server or on e linux desktop system that you use for web surfing and web browse ring, just as long as the box stays running and you don't turn it off. It's been discussed before, but probably worth repeating. Don't overlook the cost of power. If you have an old power-hungry CPU that you use for mail and web, leaving it on all the time can cost a lot. The payoff time for replacing it with a low power system can be as low as a year or two. -- 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] RasberryPi, timing and GPS receivers
Coincidentally, I just ordered a R-Pi yesterday. I have other potential uses for it, not NTP. If you are not in a hurry, it is possible to find the Soekris boards on ebay for a decent price. I got one last year, in a case, for $50. Joe Gray W5JG ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
On Tue, Oct 16, 2012 at 4:37 PM, Hal Murray hmur...@megapathdsl.net wrote: One does NOT need a dedicated server for NTP. NTP can run on a linux system that is also a web and mail server or on e linux desktop system that you use for web surfing and web browse ring, just as long as the box stays running and you don't turn it off. It's been discussed before, but probably worth repeating. Don't overlook the cost of power. If you have an old power-hungry CPU that you use for mail and web, leaving it on all the time can cost a lot. Yes. You are right. that is why I posted a like to this http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442 this board uses very little power and as you say will pay for itself quickly. You can reast your hand of the heat sink and notice there is no fan. It uses just a few watts. and can run VMware, and multiple servers The payoff time for replacing it with a low power system can be as low as a year or two. -- 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. -- 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] RasberryPi, timing and GPS receivers
Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? One option would be just a DE-9 connector with power on pin ??? (I forget). You may need inverters and/or level shifters on Rx and Tx. That would let you connect up any of the serial GPS devices. -- 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] RasberryPi, timing and GPS receivers
The miniITX mobos are quite impressive. There is no argument there. However, My simple idea was this: Since I want to keep time at 3 separate locations and wanted stratum 1 NTP, I didn't want overkill. Actually my reason for 3 different locations is simple: Internet is flakey some places and sometimes just down. I'd like to have correct time no matter what happens to the internet. The other thing I want to do is create a very small footprint NTP server that basically looks like 3-4 cartons of cigarettes stacked on top of each other. Maybe even have the power supply on the bottom of the stack. I don't know if I'll be able to do this but this is the general idea. I think maybe something like this: GPS Receiver + antenna connector --- Interface board --- CPU main board --- Shield board (mostly ground plane) --- Power supply --- If I could put this in a nice aluminum case I think it would look beautiful. -G Quoting Chris Albertson albertson.ch...@gmail.com: On Tue, Oct 16, 2012 at 4:37 PM, Hal Murray hmur...@megapathdsl.net wrote: One does NOT need a dedicated server for NTP. NTP can run on a linux system that is also a web and mail server or on e linux desktop system that you use for web surfing and web browse ring, just as long as the box stays running and you don't turn it off. It's been discussed before, but probably worth repeating. Don't overlook the cost of power. If you have an old power-hungry CPU that you use for mail and web, leaving it on all the time can cost a lot. Yes. You are right. that is why I posted a like to this http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442 this board uses very little power and as you say will pay for itself quickly. You can reast your hand of the heat sink and notice there is no fan. It uses just a few watts. and can run VMware, and multiple servers The payoff time for replacing it with a low power system can be as low as a year or two. -- 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. -- 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] RasberryPi, timing and GPS receivers
Err... I meant packs of cigarettes NOT cartons :) Quoting x...@darksmile.net: The miniITX mobos are quite impressive. There is no argument there. However, My simple idea was this: Since I want to keep time at 3 separate locations and wanted stratum 1 NTP, I didn't want overkill. Actually my reason for 3 different locations is simple: Internet is flakey some places and sometimes just down. I'd like to have correct time no matter what happens to the internet. The other thing I want to do is create a very small footprint NTP server that basically looks like 3-4 cartons of cigarettes stacked on top of each other. Maybe even have the power supply on the bottom of the stack. I don't know if I'll be able to do this but this is the general idea. I think maybe something like this: GPS Receiver + antenna connector --- Interface board --- CPU main board --- Shield board (mostly ground plane) --- Power supply --- If I could put this in a nice aluminum case I think it would look beautiful. -G Quoting Chris Albertson albertson.ch...@gmail.com: On Tue, Oct 16, 2012 at 4:37 PM, Hal Murray hmur...@megapathdsl.net wrote: One does NOT need a dedicated server for NTP. NTP can run on a linux system that is also a web and mail server or on e linux desktop system that you use for web surfing and web browse ring, just as long as the box stays running and you don't turn it off. It's been discussed before, but probably worth repeating. Don't overlook the cost of power. If you have an old power-hungry CPU that you use for mail and web, leaving it on all the time can cost a lot. Yes. You are right. that is why I posted a like to this http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442 this board uses very little power and as you say will pay for itself quickly. You can reast your hand of the heat sink and notice there is no fan. It uses just a few watts. and can run VMware, and multiple servers The payoff time for replacing it with a low power system can be as low as a year or two. -- 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. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
By the way, you need not use a USB serial adapter. Several folks are doing PPS on the gpio pins. Take a look here https://github.com/davidk/adafruit-raspberrypi-linux-pps And here http://www.frambozenbier.org/index.php/raspi-community-news/4439-george-lu-on-ntp-pps On Oct 16, 2012, at 22:03, x...@darksmile.net wrote: The miniITX mobos are quite impressive. There is no argument there. However, My simple idea was this: Since I want to keep time at 3 separate locations and wanted stratum 1 NTP, I didn't want overkill. Actually my reason for 3 different locations is simple: Internet is flakey some places and sometimes just down. I'd like to have correct time no matter what happens to the internet. The other thing I want to do is create a very small footprint NTP server that basically looks like 3-4 cartons of cigarettes stacked on top of each other. Maybe even have the power supply on the bottom of the stack. I don't know if I'll be able to do this but this is the general idea. I think maybe something like this: GPS Receiver + antenna connector --- Interface board --- CPU main board --- Shield board (mostly ground plane) --- Power supply --- If I could put this in a nice aluminum case I think it would look beautiful. -G Quoting Chris Albertson albertson.ch...@gmail.com: On Tue, Oct 16, 2012 at 4:37 PM, Hal Murray hmur...@megapathdsl.net wrote: One does NOT need a dedicated server for NTP. NTP can run on a linux system that is also a web and mail server or on e linux desktop system that you use for web surfing and web browse ring, just as long as the box stays running and you don't turn it off. It's been discussed before, but probably worth repeating. Don't overlook the cost of power. If you have an old power-hungry CPU that you use for mail and web, leaving it on all the time can cost a lot. Yes. You are right. that is why I posted a like to this http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442 this board uses very little power and as you say will pay for itself quickly. You can reast your hand of the heat sink and notice there is no fan. It uses just a few watts. and can run VMware, and multiple servers The payoff time for replacing it with a low power system can be as low as a year or two. -- 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. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] RasberryPi, timing and GPS receivers
Hello everyone, I started a new project for myself where I would use the RasperryPi Linux board as a NTP server. [] Question: What GPS timing module should I go with? No more Motorola Oncore so what's best right now? Who sell modules? What are the price ranges? Your comments are most welcome. -George, N2FGX = Excellent project! As well as the Garmin GPS 18x LVC (US $70), there is a low-cost (US $35) evaluation board from Sure Electronics: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Sure-GPS.htm I'd be interested to see a write-up of your results. 73, David GM8ARV -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
