PSN-L Message - Subject: RE: Network time standard

Hi, Remember, this is an inexpensive program. I cut and pasted the help documentation below the logs just below that. My home network is a 100 Mbs network with no traffic. I set the time out(ms) to 1ms and got a timeout error. I set it to 2ms and was able to perform the system synchronization. (See log entry for AT4) This implies that the two-way delay in my network is less than 2MS which is a reasonable assumption. I then pointed the software at the AOL time standard in San Jose CA and was not able to perform the system synchronization at 30 MS and received a timeout error and then was able to perform the system synchronization in 40 ms.(See log entry USA-2) I was also able to connect and set the time. I then configure and connect to an HP 58503A GPS network time standard which I also have running in my network using the GPSCon software utility. I configured GPSCon as a time standard and was able to perform the system synchronization (See log message HP) The one think I did notice was that I had to up the timeout count on both systems after I started to broadcast the time using the HP time standard and GPSCon software on my network. Because of that, I think there is some correlation to the decimal value in each of the log messages following the date time PM entry. I'll let you come to your own conclusions. I believe that to perform the system synchronization mean just that. There is one more issue which I think is also worth mentioning and it is the PC system clock is set by WinSDR on AT4.The GPSCon software is reading the time via a Com port connected to the HP58503A and acting as a network enabled time standard. I'm certain there will be some loss of time in the system activity on both AT1 the HP system and AT4 the system running WinSdr. Maybe Larry can comment. The Net Time service is dependent on the PC time on AT4 which is set by the GPS clock set system time function in WinSDR. On the HP system it is dependent on the system software application GPScon. Regards, Steve Hammond Aptos, CA Public Seismic Network San Jose http://www.publicseismicnetwork.com _________________ Logs pasted here ==================== Synchronize time successful from AT4 192.168.000.041[:37] Time RFC-868(TCP) 4/9/2005 4:11:48 PM.020000000 Leap:0 Stratum:2 ==================== Synchronize time error from Sunnyvale, CA, USA - 2 nist1.aol-ca.truetime.com[:123] SNTP RFC-1769/2030 ==================== Synchronize time successful from Sunnyvale, CA, USA - 2 nist1.aol-ca.truetime.com[207.200.81.113:123] SNTP RFC-1769/2030 4/9/2005 4:17:34 PM.453000000 Leap:0 Stratum:2 ==================== Synchronize time successful from HP 192.168.000.001[192.168.0.1:123] SNTP RFC-1769/2030 4/9/2005 4:26:26 PM.222000000 Leap:0 Stratum:2 ==================== ==================== --------------------------------- Help Text pasted here Client This tab sheet controls the client mode portion of Net Time Server & Client operation. Unicast mode: Set the client work in unicast (point to point) mode. a unicast client sends a request to a designated server at its unicast address and expects a reply from which it can determine the time and, optionally, the roundtrip delay and local clock offset relative to the server. Server: Specifies the time server name that will be used to run the synchronizations from. It is an arbitrary name assigned by you to represent the server when you create the time server settings. Edit...: Opens the "Edit time server settings" dialog box to modify the current time server settings. New...: Opens the "New time server settings" dialog box to create a new time server settings. Manager time servers...: Opens the "Manage time servers" dialog box to manage all time servers. Time out: Specifies a time to wait for a response from the time server. Time out(ms): Specifies how long you are willing to wait for a response from the time server (in millisecond). Retry times: Specifies how many times this server will retry the failed synchronization. Interval(sec): Specifies the number of seconds between two retries the failed synchronization. Automatic synchronization: Enables Net Time Server & Client to synchronize your system clock automatically. Interval(sec): Check this box, The Net Time Server & Client will repeat synchronization after a time period. You must specifies the number of second between two synchronization. Appointed time: Check this box, You must enter a time value, The Net Time Server & Client will automatically attempt to synchronize your system clock at this time. After program start-up: Check this box, The Net Time Server & Client will automatically attempt to synchronize your system clock once at it start-up. After create dial-up connection: Check this box, The Net Time Server & Client will automatically synchronize your system clock when it detects that dial-up networking or RAS has established a connection. Exits after synchornized: Check this box, The Net Time Server & Client will automatically terminate after successful synchronization. Exits even if attempt fails: When check the "Exits after synchornized" box, you can check this box, Enables Net Time Server & Client automatically terminate after synchronization even if it is fail. Manually synchronization: Synchronizes your system clock to selected time server manually (It cannot be disabled). Remote time: The box shows the time reported by the time Server. Get time: Requests the time from the time server. This time will be shown in the "Remote Time" box, but does not modify your system clock. Synchronize: Synchronizes your system clock to selected time server. Listen SNTP broadcast: Enables Net Time Server & Client to receive the SNTP broadcast from a multicast SNTP time server. The multicast SNTP time server periodically sends a unsolicited message to a designated local broadcast address or multicast group address and ordinarily expects no requests from clients. Note: If the listen port and the SNTP server port in "Server" tab sheet are the same, check the box will reset the Unicast box of SNTP server in "Server" tab sheet. Port: The SNTP time server broadcast port, the default is 123. Listen TimeUDP broadcast: Enables Net Time Server & Client to receive the Time(RFC-868) broadcast from a multicast Time(RFC-868) time server. The multicast Time(RFC-868) time server periodically sends a unsolicited message to a designated local broadcast address or multicast group address and ordinarily expects no requests from clients. Note: If the listen port and the TimeUDP(RFC-868) server port in "Server"tab sheet are the same, check the box will reset the Unicast box of TimeUDP(RFC-868) server in "Server" tab sheet. Port: The Time(RFC-868) time server broadcast port, the default is 37. Others: Other client options. Check synchronized flag: Check the box will cause Net Time Server & Client to accept a time stamp as valid, even if the server indicates it may not be valid. Check stratum: Check the box will cause Net Time to to accept a NTP time stamp as valid, even if the server stratum it may not be valid. The server stratum level is an indication sent with SNTP time stamps to show the level of accuracy of this system's clock. The SNTP specification allows a number from 1 to 15, with 1 being the most accurate. Notify when changes time: The option instructs Net Time Server & Client to send a notification message to all applications curently running notifying them that the system clock has changed. Contents Han-soft Software -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Keith Payea Sent: Saturday, April 09, 2005 1:53 PM To: psn-l@.............. Subject: RE: Network time standard Not all NTP clients are created equal... There are actually two standards. True NTP uses four time stamps to attempt to correct for transmission delays, and also runs a fairly complex filter based on many samples to set the time in your computer. Simple NTP (SNTP) uses just one time stamp, and is usually run once a day or every few hours with no filtering. Try to find an NTP that is based on the University of Delaware version. Dr. Mills at UDel is considered the true guru of NTP and his team have put many years into squeezing the best performance out of it. My experience when working for TrueTime (Now a division of Symmetricom) was that you could achieve 10 milliseconds or so if the server was not too far away on the public internet. If you run a local time service on your own network, the timing is much better than that. It usually takes several messages to get there due to the filtering. Also, true NTP will perform much better if you give it more than one server to work with. The software makes some attempt to evaluate the stability of each source and choose the best. Obviously, NTP is not as good as GPS, but it is very comparable to WWV or WWVB or DCF77 radio performance. Cheers, Keith ---------------------------------------------------------------------------- -- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of ChrisAtUpw@....... Sent: Saturday, April 09, 2005 1:06 PM To: psn-l@.............. Subject: Re: Network time standard In a message dated 09/04/2005, shammon1@............. writes: If you don't have a GPS, as I said, the software comes with an extensive list of network time servers that can be accessed via the Internet to obtain accurate time. Overall, the experience with this software package has been very positive and after 30-days of testing I'm now recommending it to other members of the Public Seismic Network. Hi Steve, Does it give any timing accuracies in milli seconds for the various time servers? One of the problems with time services is that while the signal may leave the server on time, it may be digitally delayed on it's way though the telecom system. Since there are many services now operating, the inaccuracy around some timing marks may be very significant. What timing errors have you measured, please? About the Public NTP Time Server Lists The lists are provided for information purposes only and represent the best information available at the current date. The operators of the servers listed do not commit to provide time service other than on a volunteer basis and with no guarantee of accuracy or availability. Further information of a technical nature can be obtained from the www.ntp.org site, the comp.protocols.time.ntp newsgroup, or the NTP Support Web. Regards, Chris Chapman

Hi, Remember, this is an = inexpensive=20 program. I cut and pasted the help documentation below the = logs just=20 below that. My home network is a 100 Mbs network with no traffic. I set = the time=20 out(ms) to 1ms and got a timeout error. I set it to 2ms and was able to = perform=20 the system synchronization. (See log entry for AT4) This implies that = the=20 two-way delay in my network is less than 2MS which is a reasonable = assumption. I=20 then pointed the software at the AOL time standard in San Jose CA and = was not=20 able to perform the system synchronization at 30 MS and received a = timeout=20 error and then was able to perform the system synchronization in 40 = ms.(See log=20 entry USA-2) I was also able to connect and set the time. I then = configure=20 and connect to an HP 58503A GPS network time standard which = I also=20 have running in my network using the GPSCon software utility. I = configured=20 GPSCon as a time standard and was able to perform the system = synchronization=20 (See log message HP) The one think I did notice was that I had to up the = timeout=20 count on both systems after I started to broadcast the time = using the=20 HP time standard and GPSCon software on my network. Because = of that,=20 I think there is some correlation to the decimal value in each of the = log=20 messages following the date time PM entry.

I'll let you come to your own = conclusions. I=20 believe that to perform the system synchronization mean just that. There = is one=20 more issue which I think is also worth mentioning and it is the PC = system clock=20 is set by WinSDR on AT4.The GPSCon software is reading the time via a = Com port=20 connected to the HP58503A and acting as a network enabled time=20 standard. I'm certain there will be some loss of time in the=20 system activity on both AT1 the HP system and AT4 the system = running=20 WinSdr. Maybe Larry can comment. The Net Time service is dependent on = the PC=20 time on AT4 which is set by the GPS clock set system time function in = WinSDR. On=20 the HP system it is dependent on the system software application=20 GPScon.

Regards, Steve Hammond Aptos,=20 CA

Public Seismic Network San = Jose

http://www.publicseismicnetw= ork.com

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Logs pasted here