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Time Server
Time Server
I had a requirement to lock a number of computers to a GPS time signal. Normally I would rely on an internet
based time server such as the ones maintained by Manchester University ( ntp.2a.mcc.ac.uk ), or the Pool
services ( eg : 0.nettime.pool.ntp.org ) . That was not an option in this case as the computers were to be
located in Nigeria with no internet and large latency times over satellite links if there is a connection.
The system is a small broadcast facility with computer playout, NAS and a three camera studio. Budget did not
allow for a more traditional off the shelf product so a little experimentation was called for.
I bought a Garmin 18 LVC from the web, hooked it up to the serial port of a desktop, ran NMEATime locking the
internal PC clock to GPS. So far straight forward enough.
Power for the Garmin 18 LVC came from a USB port - take USB lead, cut it, identify the 0 V and +5 V, connect
to the Garmin.
based time server such as the ones maintained by Manchester University ( ntp.2a.mcc.ac.uk ), or the Pool
services ( eg : 0.nettime.pool.ntp.org ) . That was not an option in this case as the computers were to be
located in Nigeria with no internet and large latency times over satellite links if there is a connection.
The system is a small broadcast facility with computer playout, NAS and a three camera studio. Budget did not
allow for a more traditional off the shelf product so a little experimentation was called for.
I bought a Garmin 18 LVC from the web, hooked it up to the serial port of a desktop, ran NMEATime locking the
internal PC clock to GPS. So far straight forward enough.
Power for the Garmin 18 LVC came from a USB port - take USB lead, cut it, identify the 0 V and +5 V, connect
to the Garmin.
DISPLAYING THE TIME : For a handy time display on a Windows screen Xnote Stop watch allows you to fill the
PC screen with the time of day which is quite handy if you want a number of people, an office or studio facility to
see the time.
For a TV facility, this output could be converted from DVI / HDMI to an SDI video signal ( eg using one of these )
and routed via the matrix around the building allowing the time of display to be shown anywhere, wall mounted
screens for example, or on the multiviewers.
Now you could take it a step further and try to make the computer output Linear Time code. But a word of caution,
you cannot just update the NTP computer clock as and when you like to otherwise the LTC would be
discontinuous. More musing on this in another post
A screen grap of the output of Xnote which can be changed to taste, colours and font.
PC screen with the time of day which is quite handy if you want a number of people, an office or studio facility to
see the time.
For a TV facility, this output could be converted from DVI / HDMI to an SDI video signal ( eg using one of these )
and routed via the matrix around the building allowing the time of display to be shown anywhere, wall mounted
screens for example, or on the multiviewers.
Now you could take it a step further and try to make the computer output Linear Time code. But a word of caution,
you cannot just update the NTP computer clock as and when you like to otherwise the LTC would be
discontinuous. More musing on this in another post
A screen grap of the output of Xnote which can be changed to taste, colours and font.
Take the Two black leads from the Garmin connect to Pin 5 of the serial port
White to Pin 2
Green to Pin 3
CONFIGURING A WINDOWS BOX AS AN NTP SERVER :
Next I had to make a couple of registry changes to allow the machine to be a NTP server - original instruction
link here .
1. Stop the Windows Time service ( use services.msc )
2. use regedit to make the following settings ( back up your registry before you do this )
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time:
Config -> AnnounceFlags = 5 ( HEX )
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\TimeProviders\NtpServer
Enabled = 1 (HEX )
DONE
3. Allow the firewall to accept INCOMING port 123
4. I gave the machine a fixed IP address
5. Change the Internet Time settings on your Win 7 / XP client machines and type in the IP address of your new
NTP server - see picture below - the IP address of my NTP box was 192.168.10.250
6. Click 'Update now' and your client / s will take the time from your NTP server.
White to Pin 2
Green to Pin 3
CONFIGURING A WINDOWS BOX AS AN NTP SERVER :
Next I had to make a couple of registry changes to allow the machine to be a NTP server - original instruction
link here .
1. Stop the Windows Time service ( use services.msc )
2. use regedit to make the following settings ( back up your registry before you do this )
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time:
Config -> AnnounceFlags = 5 ( HEX )
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\W32Time\TimeProviders\NtpServer
Enabled = 1 (HEX )
DONE
3. Allow the firewall to accept INCOMING port 123
4. I gave the machine a fixed IP address
5. Change the Internet Time settings on your Win 7 / XP client machines and type in the IP address of your new
NTP server - see picture below - the IP address of my NTP box was 192.168.10.250
6. Click 'Update now' and your client / s will take the time from your NTP server.
Below is a drawing of the extension cable I made for a Garmin GPS 18 LVC using shielded Cat 5 cable and
standard XLR 5 pin cables. This worked over 20m and I imagine would work over much longer distances. The
wiring and colours are not important but I do recommend that you run RX and TX as a quasi twisted pair,
explaining why I have used both Orange/ White and Gr
standard XLR 5 pin cables. This worked over 20m and I imagine would work over much longer distances. The
wiring and colours are not important but I do recommend that you run RX and TX as a quasi twisted pair,
explaining why I have used both Orange/ White and Gr
UPDATING CLIENTS : So we could leave it at that - we could let Windows on the client machines just update the
time. Windows does not however give you the facility to configure how regularly the time is updated. NetTime is a
fantastic little free application that can be deployed to clients, running as a windows service which can be
programmed to update the client's clock regularly as you like from either your internal network NTP time server
that you have just built, or an external internet time source.
time. Windows does not however give you the facility to configure how regularly the time is updated. NetTime is a
fantastic little free application that can be deployed to clients, running as a windows service which can be
programmed to update the client's clock regularly as you like from either your internal network NTP time server
that you have just built, or an external internet time source.
TESTING IT : To test that your NTP time server is accurate with reference to internet based time servers, open a
command prompt and type
w32tm /stripchart /computer:ntp2a.mcc.ac.uk
Assuming your computer is connected to the internet, and now taking the time from your time server, it should be
accurate to the reference source. The time server I have used in this example ( ntp2a.mcc.ac.uk ) is a UK based
one, you could equally use time.nist.gov
command prompt and type
w32tm /stripchart /computer:ntp2a.mcc.ac.uk
Assuming your computer is connected to the internet, and now taking the time from your time server, it should be
accurate to the reference source. The time server I have used in this example ( ntp2a.mcc.ac.uk ) is a UK based
one, you could equally use time.nist.gov
REFERENCES and sources:
Connecting a Garmin to a Linux machine via Lammert Bies here
Microsoft posting : Configuring Windows 7 as an NTP server
Satellite Assisted Time Keeper and the Satke.zip file in English
and Satke.zip file that I am posting here as the current link on the owner's site ( April 13 ) did not work.
Connecting a Garmin to a Linux machine via Lammert Bies here
Microsoft posting : Configuring Windows 7 as an NTP server
Satellite Assisted Time Keeper and the Satke.zip file in English
and Satke.zip file that I am posting here as the current link on the owner's site ( April 13 ) did not work.
