Re: [time-nuts] Serial port splitter s/w
A number of people have reported issues with the Raspberry Pi Ethernet hardware when used for NTP, as it is actually a USB-Ethernet bridge and the drivers may not be all they could be. I have not had problems myself but I do not run NTP on it. The Beaglebone Black (BBB) is supposed to be better in that regard since the Ethernet MAC is directly on the CPU. The BBB is also entirely open source, unlike the proprietary Broadcom CPU on the RPi. Didier KO4BB On February 26, 2014 11:32:36 AM CST, Chris Albertson albertson.ch...@gmail.com wrote: It's not going to work. If the purpose of running the Thunderbolt is only to drive NTP then you don't need LH. NTP's only tags the pulses to the nearest microsecond, nano sec on accuracy is lost on NTP. I'd even say the TB is the wrong GPS for NTP. It costs to much and uses to much power. But if you are also, or mainly, using the Thunderbolt for it's 10Mhz and NTP is a secondary function then a TB makes sense. Yes you NEED the PPS on the serial cable. Thunderbolts do not send NMEA. Thunderbolts send their own data format that is unique to Trimble. Don't modify the GPS receiver. Make a special cable adapter. When you do this pay attention to polarity of the PPS signal. It is easy to get it backwards. You want the raising edge of the TB pulse to interrupt the computer. It you invert the signal the wrong number of times the time will be off by the ouse length and I don't know if the pulse length is controlled to the level the leading edge is.Remember RS232 uses negative and positive voltage, data lines use negative logic, control lines positive. The TB's PPS is TTL level. Many rs232 ports do accept t/l level if you get the polariy correct. Again don't even bother to run an NTP server without PPS. You may as well just get time from some internet time servers. You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Likely, almost certainly you need to build a small circuit board the has two connectors that face the TB (PPS and serial) and one that faces the computer. The little perfboard makes a neat way to or connect cables but you could solder up a y--cable The best thing to do is get a cheaper GPS, and one that uses less power to drive the NTP server. The old Motorola Oncore series are cheap and the new breed of very small GPSes are good too. DOn't spend more than $40 or $50 on a GPS to drive NTP as ,again NTP record microseconds. You could free up that Windows PC too. It is not the best platform for NTP. Asmall ARM based system (even the Rasbery Pi) will outperform a Windows based NTP server. and use a LOT less power (Power cost for a NTP server is more than you think, it came to about $300 a year for me if I used a standard PC and a thunderbolt. Switching to a very tiny ARM based system and a smaller GPS gave as good performance and power savings paid for the hardware in 1/2 a year. $.21/KWH about 170W and 8760 hours per year comes to a $300 power bill. My current system is powered by a 1000 mw plug-in power cube and does not need a cooling fan. On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge ___ time-nuts mailing 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. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. ___ time-nuts mailing 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] Serial port splitter s/w
Yes the BBB has about twice or more the performance over the Pi except in graphics. The Pi has a faster GPU. But in the case of an NTP server you likely would never connect a monitor or keyboard to the computer so the GPU will go unused. However the NTP is very un-demanding and will only see on average of maybe about one network packet per second or less. In fact using an entire BBB or Pi just for NTP is kind of a waste as it could be doing other things at the same time. Put some disks on it as use it as a file server for backups for the other computers. Lots of other uses you could put it to. On another list server I'm reading about how to use discarded cell phones. These older Andriod cell phones that people don't want are many times available for fee and have mamory and processors like those in the BBB or Pi. They use very little power, have built-in barrty backup and have nice built in displays. They can be re-purposed as tiny computers. (Think of a TIC or GPSDO with a color display and touch screen user interface.) The problem is making the physical connections, that takes some work and reading. On Thu, Feb 27, 2014 at 6:56 AM, Didier Juges shali...@gmail.com wrote: A number of people have reported issues with the Raspberry Pi Ethernet hardware when used for NTP, as it is actually a USB-Ethernet bridge and the drivers may not be all they could be. I have not had problems myself but I do not run NTP on it. The Beaglebone Black (BBB) is supposed to be better in that regard since the Ethernet MAC is directly on the CPU. The BBB is also entirely open source, unlike the proprietary Broadcom CPU on the RPi. Didier KO4BB On February 26, 2014 11:32:36 AM CST, Chris Albertson albertson.ch...@gmail.com wrote: It's not going to work. If the purpose of running the Thunderbolt is only to drive NTP then you don't need LH. NTP's only tags the pulses to the nearest microsecond, nano sec on accuracy is lost on NTP. I'd even say the TB is the wrong GPS for NTP. It costs to much and uses to much power. But if you are also, or mainly, using the Thunderbolt for it's 10Mhz and NTP is a secondary function then a TB makes sense. Yes you NEED the PPS on the serial cable. Thunderbolts do not send NMEA. Thunderbolts send their own data format that is unique to Trimble. Don't modify the GPS receiver. Make a special cable adapter. When you do this pay attention to polarity of the PPS signal. It is easy to get it backwards. You want the raising edge of the TB pulse to interrupt the computer. It you invert the signal the wrong number of times the time will be off by the ouse length and I don't know if the pulse length is controlled to the level the leading edge is.Remember RS232 uses negative and positive voltage, data lines use negative logic, control lines positive. The TB's PPS is TTL level. Many rs232 ports do accept t/l level if you get the polariy correct. Again don't even bother to run an NTP server without PPS. You may as well just get time from some internet time servers. You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Likely, almost certainly you need to build a small circuit board the has two connectors that face the TB (PPS and serial) and one that faces the computer. The little perfboard makes a neat way to or connect cables but you could solder up a y--cable The best thing to do is get a cheaper GPS, and one that uses less power to drive the NTP server. The old Motorola Oncore series are cheap and the new breed of very small GPSes are good too. DOn't spend more than $40 or $50 on a GPS to drive NTP as ,again NTP record microseconds. You could free up that Windows PC too. It is not the best platform for NTP. Asmall ARM based system (even the Rasbery Pi) will outperform a Windows based NTP server. and use a LOT less power (Power cost for a NTP server is more than you think, it came to about $300 a year for me if I used a standard PC and a thunderbolt. Switching to a very tiny ARM based system and a smaller GPS gave as good performance and power savings paid for the hardware in 1/2 a year. $.21/KWH about 170W and 8760 hours per year comes to a $300 power bill. My current system is powered by a 1000 mw plug-in power cube and does not need a cooling fan. On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the
Re: [time-nuts] Serial port splitter s/w
A number of people have reported issues with the Raspberry Pi Ethernet hardware when used for NTP, as it is actually a USB-Ethernet bridge and the drivers may not be all they could be. I have not had problems myself but I do not run NTP on it. The Beaglebone Black (BBB) is supposed to be better in that regard since the Ethernet MAC is directly on the CPU. The BBB is also entirely open source, unlike the proprietary Broadcom CPU on the RPi. Didier KO4BB Didier, Here are the results I saw when using Ethernet sync for NTP on a Raspberry Pi: http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#results Syncing just from my Cable Modem WAN connection it's quite bad (offsets +/- 3 milliseconds), but when syncing to local stratum-1 servers the offsets were reduced to something slightly in excess of +/- 20 microseconds. Adding PPS reduces that to a couple of microseconds (with Linux 3.6.11 compiled as a non-tickless system) as seen further down under the Current performance heading. Perhaps there are equivalent graphs for the BBB system somewhere? The Raspberry Pi is sufficiently open that you can recompile programs, and even recompile the kernel for it. 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.
[time-nuts] Serial port splitter s/w
I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge ___ time-nuts mailing 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] Serial port splitter s/w
I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge = David, Can't comment on the COM port splitters. For best results with NTP you need a PPS signal on the RS-232 DCD line. Using NMEA alone is often worse than just Internet sync. Look for a white flash with my Serial Port LEDs program: http://www.satsignal.eu/software/net.htm#SerialPortLEDs The pulse needs to be rather more than a few microseconds - 100-200 milliseconds is typically used. Cheers, David -- 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.
Re: [time-nuts] Serial port splitter s/w
It's not going to work. If the purpose of running the Thunderbolt is only to drive NTP then you don't need LH. NTP's only tags the pulses to the nearest microsecond, nano sec on accuracy is lost on NTP. I'd even say the TB is the wrong GPS for NTP. It costs to much and uses to much power. But if you are also, or mainly, using the Thunderbolt for it's 10Mhz and NTP is a secondary function then a TB makes sense. Yes you NEED the PPS on the serial cable. Thunderbolts do not send NMEA. Thunderbolts send their own data format that is unique to Trimble. Don't modify the GPS receiver. Make a special cable adapter. When you do this pay attention to polarity of the PPS signal. It is easy to get it backwards. You want the raising edge of the TB pulse to interrupt the computer. It you invert the signal the wrong number of times the time will be off by the ouse length and I don't know if the pulse length is controlled to the level the leading edge is.Remember RS232 uses negative and positive voltage, data lines use negative logic, control lines positive. The TB's PPS is TTL level. Many rs232 ports do accept t/l level if you get the polariy correct. Again don't even bother to run an NTP server without PPS. You may as well just get time from some internet time servers. You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Likely, almost certainly you need to build a small circuit board the has two connectors that face the TB (PPS and serial) and one that faces the computer. The little perfboard makes a neat way to or connect cables but you could solder up a y--cable The best thing to do is get a cheaper GPS, and one that uses less power to drive the NTP server. The old Motorola Oncore series are cheap and the new breed of very small GPSes are good too. DOn't spend more than $40 or $50 on a GPS to drive NTP as ,again NTP record microseconds. You could free up that Windows PC too. It is not the best platform for NTP. Asmall ARM based system (even the Rasbery Pi) will outperform a Windows based NTP server. and use a LOT less power (Power cost for a NTP server is more than you think, it came to about $300 a year for me if I used a standard PC and a thunderbolt. Switching to a very tiny ARM based system and a smaller GPS gave as good performance and power savings paid for the hardware in 1/2 a year. $.21/KWH about 170W and 8760 hours per year comes to a $300 power bill. My current system is powered by a 1000 mw plug-in power cube and does not need a cooling fan. On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge ___ time-nuts mailing 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] Serial port splitter s/w
Here is interesting topic about NTP on Raspberry PI (typical usage of ARM and Linux bread on top of it) http://www.synclab.org/?tag=testing Basically, TCP stack on ARM usually come from one source - its a Adam Dunken TCP stack. Then its is MII part and the hardware which doing Ethernet. In my opinion, MCU (ARM) could provide excellent Ethernet functions. However its far from serious dedicated ethernet controllers we could see in enterprise servers. Regards, V.P. On 2014-02-26 12:32, Chris Albertson wrote: It's not going to work. If the purpose of running the Thunderbolt is only to drive NTP then you don't need LH. NTP's only tags the pulses to the nearest microsecond, nano sec on accuracy is lost on NTP. I'd even say the TB is the wrong GPS for NTP. It costs to much and uses to much power. But if you are also, or mainly, using the Thunderbolt for it's 10Mhz and NTP is a secondary function then a TB makes sense. Yes you NEED the PPS on the serial cable. Thunderbolts do not send NMEA. Thunderbolts send their own data format that is unique to Trimble. Don't modify the GPS receiver. Make a special cable adapter. When you do this pay attention to polarity of the PPS signal. It is easy to get it backwards. You want the raising edge of the TB pulse to interrupt the computer. It you invert the signal the wrong number of times the time will be off by the ouse length and I don't know if the pulse length is controlled to the level the leading edge is.Remember RS232 uses negative and positive voltage, data lines use negative logic, control lines positive. The TB's PPS is TTL level. Many rs232 ports do accept t/l level if you get the polariy correct. Again don't even bother to run an NTP server without PPS. You may as well just get time from some internet time servers. You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Likely, almost certainly you need to build a small circuit board the has two connectors that face the TB (PPS and serial) and one that faces the computer. The little perfboard makes a neat way to or connect cables but you could solder up a y--cable The best thing to do is get a cheaper GPS, and one that uses less power to drive the NTP server. The old Motorola Oncore series are cheap and the new breed of very small GPSes are good too. DOn't spend more than $40 or $50 on a GPS to drive NTP as ,again NTP record microseconds. You could free up that Windows PC too. It is not the best platform for NTP. Asmall ARM based system (even the Rasbery Pi) will outperform a Windows based NTP server. and use a LOT less power (Power cost for a NTP server is more than you think, it came to about $300 a year for me if I used a standard PC and a thunderbolt. Switching to a very tiny ARM based system and a smaller GPS gave as good performance and power savings paid for the hardware in 1/2 a year. $.21/KWH about 170W and 8760 hours per year comes to a $300 power bill. My current system is powered by a 1000 mw plug-in power cube and does not need a cooling fan. On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- WBW, V.P. ___ time-nuts mailing 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] Serial port splitter s/w
I have some problems with My 8505A Analyzer, it has no RF output, I checked the YTO and other frequency dividers and it appears to be OK some times there is RF output only it will not tune and it seems to cut out as I tune trough the frequency range. Thank You Sal C. Cornacchia Electronic RF Engineer Ret. On Wednesday, February 26, 2014 12:33:17 PM, Chris Albertson albertson.ch...@gmail.com wrote: It's not going to work. If the purpose of running the Thunderbolt is only to drive NTP then you don't need LH. NTP's only tags the pulses to the nearest microsecond, nano sec on accuracy is lost on NTP. I'd even say the TB is the wrong GPS for NTP. It costs to much and uses to much power. But if you are also, or mainly, using the Thunderbolt for it's 10Mhz and NTP is a secondary function then a TB makes sense. Yes you NEED the PPS on the serial cable. Thunderbolts do not send NMEA. Thunderbolts send their own data format that is unique to Trimble. Don't modify the GPS receiver. Make a special cable adapter. When you do this pay attention to polarity of the PPS signal. It is easy to get it backwards. You want the raising edge of the TB pulse to interrupt the computer. It you invert the signal the wrong number of times the time will be off by the ouse length and I don't know if the pulse length is controlled to the level the leading edge is. Remember RS232 uses negative and positive voltage, data lines use negative logic, control lines positive. The TB's PPS is TTL level. Many rs232 ports do accept t/l level if you get the polariy correct. Again don't even bother to run an NTP server without PPS. You may as well just get time from some internet time servers. You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Likely, almost certainly you need to build a small circuit board the has two connectors that face the TB (PPS and serial) and one that faces the computer. The little perfboard makes a neat way to or connect cables but you could solder up a y--cable The best thing to do is get a cheaper GPS, and one that uses less power to drive the NTP server. The old Motorola Oncore series are cheap and the new breed of very small GPSes are good too. DOn't spend more than $40 or $50 on a GPS to drive NTP as ,again NTP record microseconds. You could free up that Windows PC too. It is not the best platform for NTP. Asmall ARM based system (even the Rasbery Pi) will outperform a Windows based NTP server. and use a LOT less power (Power cost for a NTP server is more than you think, it came to about $300 a year for me if I used a standard PC and a thunderbolt. Switching to a very tiny ARM based system and a smaller GPS gave as good performance and power savings paid for the hardware in 1/2 a year. $.21/KWH about 170W and 8760 hours per year comes to a $300 power bill. My current system is powered by a 1000 mw plug-in power cube and does not need a cooling fan. On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge ___ time-nuts mailing 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] Serial port splitter s/w
Ummm think you sent the question to the wrong group perhaps? On Wed, Feb 26, 2014 at 12:50 PM, corc...@yahoo.ca wrote: I have some problems with My 8505A Analyzer, it has no RF output, I checked the YTO and other frequency dividers and it appears to be OK some times there is RF output only it will not tune and it seems to cut out as I tune trough the frequency range. Thank You Sal C. Cornacchia Electronic RF Engineer Ret. On Wednesday, February 26, 2014 12:33:17 PM, Chris Albertson albertson.ch...@gmail.com wrote: It's not going to work. If the purpose of running the Thunderbolt is only to drive NTP then you don't need LH. NTP's only tags the pulses to the nearest microsecond, nano sec on accuracy is lost on NTP. I'd even say the TB is the wrong GPS for NTP. It costs to much and uses to much power. But if you are also, or mainly, using the Thunderbolt for it's 10Mhz and NTP is a secondary function then a TB makes sense. Yes you NEED the PPS on the serial cable. Thunderbolts do not send NMEA. Thunderbolts send their own data format that is unique to Trimble. Don't modify the GPS receiver. Make a special cable adapter. When you do this pay attention to polarity of the PPS signal. It is easy to get it backwards. You want the raising edge of the TB pulse to interrupt the computer. It you invert the signal the wrong number of times the time will be off by the ouse length and I don't know if the pulse length is controlled to the level the leading edge is.Remember RS232 uses negative and positive voltage, data lines use negative logic, control lines positive. The TB's PPS is TTL level. Many rs232 ports do accept t/l level if you get the polariy correct. Again don't even bother to run an NTP server without PPS. You may as well just get time from some internet time servers. You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Likely, almost certainly you need to build a small circuit board the has two connectors that face the TB (PPS and serial) and one that faces the computer. The little perfboard makes a neat way to or connect cables but you could solder up a y--cable The best thing to do is get a cheaper GPS, and one that uses less power to drive the NTP server. The old Motorola Oncore series are cheap and the new breed of very small GPSes are good too. DOn't spend more than $40 or $50 on a GPS to drive NTP as ,again NTP record microseconds. You could free up that Windows PC too. It is not the best platform for NTP. Asmall ARM based system (even the Rasbery Pi) will outperform a Windows based NTP server. and use a LOT less power (Power cost for a NTP server is more than you think, it came to about $300 a year for me if I used a standard PC and a thunderbolt. Switching to a very tiny ARM based system and a smaller GPS gave as good performance and power savings paid for the hardware in 1/2 a year. $.21/KWH about 170W and 8760 hours per year comes to a $300 power bill. My current system is powered by a 1000 mw plug-in power cube and does not need a cooling fan. On Wed, Feb 26, 2014 at 7:53 AM, David C. Partridge david.partri...@perdrix.co.uk wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge ___ time-nuts mailing 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] Serial port splitter s/w
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Re: [time-nuts] Serial port splitter s/w
david.partri...@perdrix.co.uk said: I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? If your lines are short, you don't need fancy hardware. The RS-232 driver will drive 2 lines. Just take 2 cables, cut them in half, connect the wires... Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Yes, you need to connect the PPS. You can get the PPS by just opening up the TB and soldering a wire from the BNC to the DB-9. You may/probably need a pulse stretcher. I have one TB where I changed the PPS wire to a diode and R/C. It's a kludge, but works. You can get a clean version from TAPR. It needs power. http://tapr.org/kits_fatpps.html TBs don't talk NMEA. Use the Palisade driver. The problem is that both LH and ntpd expect to talk to the TB. It may work if you let one of them listen to whatever traffic the other one generates. ntpd just sets it up so a couple of packet types get sent every second. If LH does something similar, it should work. (I think ntpd will ignore everything else. It it complains too loudly we can fix it.) -- 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] Serial port splitter s/w
On Wed, Feb 26, 2014 at 12:32 PM, Chris Albertson albertson.ch...@gmail.com wrote: You can NOT control a GPS from two ports. Both NTP and LH will try to send commands to the GPS. Actually the Palisades driver doesn't send commands to the Thunderbolt. It sends a single invalid command requesting auto messages and then parses the data stream. As long as primary timing packets are received it works. A Thunderbolt will wake up doing the right thing and if not I believe LH will correctly initialize it. The deeper point is correct and the Trimble devices I have experience with have ~100ms of jitter. Props to Jackson Labs -- my Fury has O(10) microseconds of jitter using NMEA messages. If only they were $100. ___ time-nuts mailing 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] Serial port splitter s/w
On Wed, Feb 26, 2014 at 9:53 AM, d0ct0r t...@patoka.org wrote: Here is interesting topic about NTP on Raspberry PI (typical usage of ARM and Linux bread on top of it) The article addresses using the Pi as an NTP server with stratum 0. In other words as an NTP server that uses another NTP server as its reference clock so it uses Ethernet for time transfer. In the OP's case he wants to build a Stratum = 0 server that uses GPS as a reference clock. Ethernet noise will not be an issue. The Pi might or might not be the best choise. There are now so many small and cheap ARM systems. You can even re-purpose an old ARM based router or small NAS. box. Except as an exercise there is almost no point any more using GPS to drive a local NTP server if you have a very good Internet connection. My fiber Internet connection is as good as Ethernet as the Pool Servers work well for me. Those using slower or a widely shared connection might not get as good a result. -- 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] Serial port splitter s/w
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Re: [time-nuts] Serial port splitter s/w
From: Chris Albertson [] Except as an exercise there is almost no point any more using GPS to drive a local NTP server if you have a very good Internet connection. My fiber Internet connection is as good as Ethernet as the Pool Servers work well for me. Those using slower or a widely shared connection might not get as good a result. Chris Albertson Redondo Beach, California === The Raspberry Pi with GPS/PPS certainly beats any internet connection I've ever had delivered to this house, though: http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html http://www.satsignal.eu/mrtg/performance_ntp.php Cheers, David -- 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.
Re: [time-nuts] Serial port splitter s/w
On Wed, Feb 26, 2014 at 11:15 AM, David J Taylor david-tay...@blueyonder.co.uk wrote: The Raspberry Pi with GPS/PPS certainly beats any internet connection I've ever had delivered to this house, though: Yes it will. But the point of the server is to deliver time to other computers. The the measure is goodness is not the accuracy of your local NTP server but the accuracy of the client computers that use it. So if I point my desktop computer at a set of 5 to 7 Internet pool servers or it I point the same desktop to my local NTP server I don't se a lot of difference. With the notebook computer using WiFi I don't see any difference. This is what I moment by saying it is hardly worth it if you happen to have Ethernet-like connectivity all the way back to your ISP. Of douse many people don't and have to use DSL or Cable TV lines. The ARM has some real potential for time keeping. Inside the chip in addition to the ARM CPU are two RPU processors. Thee run at exactly 200MHz one instruction per cycle with very deterministic timing. They have access to all of the ARM memory and interrupts. They are in effect two micro controllers that are in addition to however many ARM cores there are. A really good project would be to move NTP's PPS timing to a PRU.But as I said the weak link is getting time OUT of the NTP server, not into it. But again the ARM is great for real time because it has both the ARM cores runnig Linux and the PRUs that you can program in assembly with deterministic timing. But as of today I don't think the PRUs are used for this but see below, lots of potential uses for building things like TICs http://processors.wiki.ti.com/index.php/Programmable_Realtime_Unit_Subsystem http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html http://www.satsignal.eu/mrtg/performance_ntp.php Cheers, David -- 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. -- 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] Serial port splitter s/w
From: Chris Albertson Sent: Wednesday, February 26, 2014 7:32 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Serial port splitter s/w On Wed, Feb 26, 2014 at 11:15 AM, David J Taylor david-tay...@blueyonder.co.uk wrote: The Raspberry Pi with GPS/PPS certainly beats any internet connection I've ever had delivered to this house, though: Yes it will. But the point of the server is to deliver time to other computers. The the measure is goodness is not the accuracy of your local NTP server but the accuracy of the client computers that use it. So if I point my desktop computer at a set of 5 to 7 Internet pool servers or it I point the same desktop to my local NTP server I don't se a lot of difference. With the notebook computer using WiFi I don't see any difference. This is what I moment by saying it is hardly worth it if you happen to have Ethernet-like connectivity all the way back to your ISP. Of douse many people don't and have to use DSL or Cable TV lines. The ARM has some real potential for time keeping. Inside the chip in addition to the ARM CPU are two RPU processors. Thee run at exactly 200MHz one instruction per cycle with very deterministic timing. They have access to all of the ARM memory and interrupts. They are in effect two micro controllers that are in addition to however many ARM cores there are. A really good project would be to move NTP's PPS timing to a PRU.But as I said the weak link is getting time OUT of the NTP server, not into it. But again the ARM is great for real time because it has both the ARM cores runnig Linux and the PRUs that you can program in assembly with deterministic timing. But as of today I don't think the PRUs are used for this but see below, lots of potential uses for building things like TICs http://processors.wiki.ti.com/index.php/Programmable_Realtime_Unit_Subsystem = Chris, even with Wi-Fi connected computers, mostly running Windows, there is a huge difference between talking to a stratum-1 server on my LAN compared to running just Internet servers. Our experiences differ, as I am on a cable modem connection from the UK's Virgin Media. Folks need to measure what performance they are getting and choose their own best path, otherwise it's guesswork. Cheers, David -- 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.
Re: [time-nuts] Serial port splitter s/w
Chris, even with Wi-Fi connected computers, mostly running Windows, there is a huge difference between talking to a stratum-1 server on my LAN compared to running just Internet servers. Our experiences differ, as I am on a cable modem connection from the UK's Virgin Media. Folks need to measure what performance they are getting and choose their own best path, otherwise it's guesswork. Yes, exactly. It depends entirely on your internet connection. As soon as you get even slow 10Mb/s fiber the distinction between LAN and Internet starts to melt away. The problem with Cable TV is that it is a shared connection with who knows how many others. Shared media have collisions with back off and retries and are not deterministic. I do have a local NTP server. I had one back in the days of dial-up phone modems and still have one with my current fiber connection. I was just pointing out that the local NTP server is less useful as the Internet connections get better. Every few years I get motivated to improve the NTP server. The next step is for certain going to be to use the ARM's PRUs somehow. That would remove the effect of the OS from timing which is now the largest source of error. Cheers, David -- 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. -- 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] Serial port splitter s/w
On Wed, Feb 26, 2014 at 2:05 PM, Chris Albertson albertson.ch...@gmail.comwrote: Chris, even with Wi-Fi connected computers, mostly running Windows, there is a huge difference between talking to a stratum-1 server on my LAN compared to running just Internet servers. Our experiences differ, as I am on a cable modem connection from the UK's Virgin Media. Folks need to measure what performance they are getting and choose their own best path, otherwise it's guesswork. Yes, exactly. It depends entirely on your internet connection. As soon as you get even slow 10Mb/s fiber the distinction between LAN and Internet starts to melt away. The problem with Cable TV is that it is a shared connection with who knows how many others. Shared media have collisions with back off and retries and are not deterministic. Not generally with broadband. (True broadband that is, such as Internet-over-cable. I do find it annoying that all higher-speed, i.e. non-dial-up, access is referred to as broadband.) There are no collisions coming downstream because there is only one source -- the head end. There you just have variable queueing delays if a burst of traffic exceeding downstream capacity arrives at once. Collisions are possible on the upstream but less likely. I do have a local NTP server. I had one back in the days of dial-up phone modems and still have one with my current fiber connection. I was just pointing out that the local NTP server is less useful as the Internet connections get better. True, but far more deterministic. As you suggest, a local NTP server is independent of upstream traffic, queueing, and backoff/retry delays. Personally I would like to have a local stratum-1 source for that reason. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ time-nuts mailing 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] Serial port splitter s/w
You guys have me persuaded - I'll get a Raspberry Pi ... Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David J Taylor Sent: 26 February 2014 19:15 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Serial port splitter s/w The Raspberry Pi with GPS/PPS certainly beats any internet connection I've ever had delivered to this house, though: http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html http://www.satsignal.eu/mrtg/performance_ntp.php Cheers, David -- 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.
Re: [time-nuts] Serial port splitter s/w
Serial outputs can usually drive several serial inputs if the cables are short (to avoid reflections). You can wire it yourself, serial out from the TB to both LH and NTP, serial in from LH only. David On 2/26/14 11:51 AM, David J Taylor wrote: I'm running Meinberg NTP on the Windows 7 x64 machine to which my Thunderbolt is attached. I'd like to be able to share the serial port between LH and NTP so that I can run the machine as an NTP Stratum 1 server locked to the TB, and also be able to use LH to check things. I looked around the with Google, and saw *numerous serial port splitters. Which is recommended? Also what's the best way how to configure NTP to lock the the TB on a serial port? Do I need to modify the TB to deliver the PPS down one of the serial data lines or will NTP work well by parsing the NMEA time messages? Many thanks David Partridge = David, Can't comment on the COM port splitters. For best results with NTP you need a PPS signal on the RS-232 DCD line. Using NMEA alone is often worse than just Internet sync. Look for a white flash with my Serial Port LEDs program: http://www.satsignal.eu/software/net.htm#SerialPortLEDs The pulse needs to be rather more than a few microseconds - 100-200 milliseconds is typically used. Cheers, David ___ time-nuts mailing 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] Serial port splitter s/w
On Wed, Feb 26, 2014 at 1:30 PM, David C. Partridge david.partri...@perdrix.co.uk wrote: You guys have me persuaded - I'll get a Raspberry Pi ... You might want to think a little more about which to get. The Pi is OK and will work fine but look at BeagleBone Black. It's a little nicer for hardware hackers. Cost is $5 different. You can read specs and the respective forums. One thing to watch out for is that all ARM boards run on 3.3 volts. The serial ports are 3.3 volts. Don't connect a 5 volt signal and certainly NOT a real RS232 level signal -- 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] Serial port splitter s/w
From: Chris Albertson You might want to think a little more about which to get. The Pi is OK and will work fine but look at BeagleBone Black. It's a little nicer for hardware hackers. Cost is $5 different. You can read specs and the respective forums. One thing to watch out for is that all ARM boards run on 3.3 volts. The serial ports are 3.3 volts. Don't connect a 5 volt signal and certainly NOT a real RS232 level signal === It would be interesting to see a performance comparison between the RPi and the BBB. when running NTP from a PPS signal. The RPi is much more popular and has a much wider user base, though. I've used mine for a 1.09 GHz ADS-B receiver (aircraft tracking), logging room temperature, as a wall-clock synced from NTP, of course, and for various other applications. The GPS units you can get these days support 3.3V operation so that's not a difficulty in practice. I've used these units for both with soldering and no soldering needed choices: With soldering: http://www.adafruit.com/products/746 No soldering required http://ava.upuaut.net/store/index.php?route=product/productpath=59_60product_id=95 Certainly, for external true RS-232 devices an interface is needed, but these can again be bought for the Raspberry Pi (data only): http://www.davidhunt.ie/?p=3091 http://www.abelectronics.co.uk/products/3/Raspberry-Pi/29/Serial-Pi-RS232-Interface Cheers, David -- 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.
