I want to synchronize the time with NTP over JavaScript. The client can be a normal pc or a smartphone or tablet. The connection could be WLAN or 3G, etc.

I already found this questions and sites

• how to get ntp time from through javascript
• JavaScript NTP time
• Synchronize time in javascript with a good precision (>0.5s) (NTP-like)

first and second links using the a timestamp from this server: .json But the date object has only second precision. I want a better precision, if possible ~ 10 ms. (I know the precision depends on the connection and round trip time)
Edit: 10 ms is almost impossible. I want the most precision offset.

The third link shows a JavaScript library, but it does not use a direct connection to a ntp server. The solution of the fourth link is most near to that what I want. But its for synchronizing two clients through a 'own' server. Is there a way to synchronize it directly to a ntp pool like pool.ntp ?

I want to synchronize the time with NTP over JavaScript. The client can be a normal pc or a smartphone or tablet. The connection could be WLAN or 3G, etc.

I already found this questions and sites

• how to get ntp time from through javascript
• JavaScript NTP time
• http://jehiah.cz/a/ntp-for-javascript
• Synchronize time in javascript with a good precision (>0.5s) (NTP-like)

first and second links using the a timestamp from this server: http://json-time.appspot./time.json But the date object has only second precision. I want a better precision, if possible ~ 10 ms. (I know the precision depends on the connection and round trip time)
Edit: 10 ms is almost impossible. I want the most precision offset.

The third link shows a JavaScript library, but it does not use a direct connection to a ntp server. The solution of the fourth link is most near to that what I want. But its for synchronizing two clients through a 'own' server. Is there a way to synchronize it directly to a ntp pool like pool.ntp ?

• javascript
• synchronization
• ntp

• Pinging 8.8.8.8 with 32 bytes of data: Reply from 8.8.8.8: bytes=32 time=68ms TTL=44 Ping statistics for 8.8.8.8: Packets: Sent = 1, Received = 1, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 68ms, Maximum = 68ms, Average = 68ms How are you going to get sub 10ms with that? – starbolin Commented Jun 5, 2012 at 16:50
• You might be interested in Sync JS time between multiple devices, which offers many solutions. – Bergi Commented Jun 5, 2012 at 16:57
• @Bergi This is abou synchronization, but not with NTP – timaschew Commented Jun 5, 2012 at 17:04
• @starbolin The error ist worst case is only half of the round trip time. Okay 10ms isn't possible. I want only the most precision value. – timaschew Commented Jun 5, 2012 at 21:22
• No, the uncertainty, without clock disciplining, is the difference between the best case one way time and the worst case one-way time. Which may, at times, be more than the average round trip time. Worst case time is not garanteed in a best-effort network ( TCP/IP ). – starbolin Commented Jun 6, 2012 at 3:31

1 Answer 1

An NTP client servos the puter's own internal clock for resolution. The client must estimate UDP round trip times and change the inernal clock rate ,slowly, to minimize the average error.